EP3119735B1 - Facility for producing an explosive by mixing with a gasification reagent - Google Patents

Description

The present invention relates to the field of the preparation and use of explosive products including explosive emulsions used in the extraction of raw material and mining industry.

• une phase continue organique, constituée mélange de divers combustibles tel que huiles minérales, gasoil, et
• une phase aqueuse discontinue constituée de divers sels comburants en solution aqueuse.

These products are systematically constituted from a so-called inverse base emulsion or "water in oil" also called "matrix" obtained by a mixture of:

• an organic continuous phase, constituted mixture of various fuels such as mineral oils, gas oil, and
• a discontinuous aqueous phase consisting of various oxidizing salts in aqueous solution.

The most frequently used oxidizing raw materials in this industry are: ammonium nitrate, sodium nitrate, calcium nitrate. With regard to fuels, it is gas oil that is either pure or mixed with new or used mineral oils, especially recycled motor oil.

To give this mixture improved detonation characteristics, it is necessary, in known manner, to disperse homogeneously "porosities" within it. To date, the method mainly used in the industry for the sensitization of bulk or cartridge emulsions is chemical gasification. This consists in generating as chemically and as homogeneously as possible gas bubbles in the medium. The "porosities" thus obtained will form hot spots, initiators of the detonation and thus help maintain the propagation of a shock wave from the priming system.

There are other ways, well known to create these "porosities" in the emulsion. In particular, small hollow bodies ranging from a few tens to a few hundred microns can be dispersed. Among these, there may be mentioned glass microbeads, thermoplastic polymer beads or expanded polystyrene beads.

The present invention relates to the manufacture of explosive charges from an emulsion or matrix that is sensitized by mixing with reagents that react with the emulsion and generate a chemical gasification.

More particularly, but without limitation, to react with ammonium of said emulsion matrix (hereinafter M), a gasification reagent (hereinafter R) based on sodium nitrite or equivalent is used. in the presence of a catalyst such as an acid, especially acetic acid of the following chemical reaction:

This chemical reaction generates nitrogen gas which leads to a decrease in the final density of the mixture product obtained. Generally, we go from an initial density di of the matrix M di = 1 to 2 that we decrease to a value dj = 0.5 to 1.5 depending on the proportion of reagent R / M, typically di = 1.4 and dj = 1.2 at 0.9.

In the rest of the text herein is understood to mean a matrix or emulsion, the emulsion itself supplemented with a catalyst component and preferably also water to serve as a lubricant to facilitate the displacement of the viscous emulsion within the pipeline. loading.

Indeed, the present invention relates more particularly to the use of these products in a hole in which a priming charge and a detonator wire are placed and in which the explosive products (emulsion mixture + gasification reagent) are transferred using a flexible hose.

In EP0338707 an installation in which the two emulsion and gasification reagent components are mixed at a kind of rigid lance or gun which is introduced in small quantities into a hole. It is not an installation in which products are remotely stored in larger quantities in a truck and transferred using pipe (s) unwound (s) from a reel to a load hole . This type of installation can only be used to load holes of small diameter (less than 50mm) as it is insisted several times in this document. This installation is therefore not suitable for loading holes with products stored remotely in a truck and transferred to the charging hole using a pipe unrolled from a reel. In addition, the two components (emulsion and gasification reagent) are introduced with a pump with two bodies and two pistons which does not allow to vary the relative proportion of two components in the mixture during filling of the hole.

The present invention relates more particularly to a process in which mixing of the emulsion and porosity reactants is carried out at the site of use of the explosive and more particularly in a hole, in particular a borehole, which the an explosive charge is supplied by means of a transfer line from an installation where the emulsion matrix is made and / or stored at a distance from the hole. Typically the hole has a depth of 5 to 30m and a diameter of 5 to 50 cm.

The basic raw material, the emulsion matrix, can be produced on site by a modular plant as described in PCT / FR2014 / 050032 or through mobile installation called UMFE (Mobile Explosive Manufacturing Unit) therefore trucks carrying materials useful for manufacturing that go to the site of use (mines, quarries or construction site) for the production of explosives.

The transfer and mixing of the 2 components, emulsion on the one hand and gasification reagent on the other hand poses a number of difficulties.

Usually, as in WO 97/24298 and EP 612971 the reactants and catalyst are introduced together and mixed with the emulsion matrix in a static mixer upstream of the loading line, the downstream end of which is introduced into the mine hole to pump the explosive product therein. The reason is that it is thus possible to convey the mixture in a single pipe that is unwound from a winding drum at its upstream end located at a distance from the hole typically 30 to 100 m. On the other hand, it avoids placing inside the hole metal parts such as the static mixer which by the size it generates, interfere or make it more difficult handling in the hole and especially to avoid shocks with the rock mass of my wall of the hole being able to cause sparks near the charge of priming and / or being in contact with the detonator wire damaged this one.

In US 5,524,523 a device for transferring components into the hole is described with a pipe 12 containing three pipes arranged side by side, in parallel with a first, the base emulsion feed pipe 16 already mixed with a gasification reagent referred to as " gassing solution ", the other pipes used to provide other additives such as stuffing products (" stemming "). In US 5,524,523 The emulsion and the gasification reagent are thus already transferred as a mixture (not separately) to the same duct 16 before being introduced into a static mixer located at the outlet end of the duct 20 in which mixing and reaction of the two components is complete.

This introduction of the two components together (emulsion and gasification reagent) upstream of the same pipe, however, has several disadvantages. Gasification begins after the introduction of the gasification reagent and the mixture begins to be explosive from the introduction of the gasification reagent therefore in the transfer pipe which creates pressure increase constraints in the pipe and risks to safety because the pipe is filled with explosive. In addition, one can not vary the density in real time during filling of the hole, because there is a relatively large and reliably indeterminable product contained in the pipe to be taken into account. And, therefore, if we want to vary the density in real time of the final product arriving in the hole, depending on the power of the explosion to produce, as is the case in practice, there is a quantity unreliable reagent contained in the conduct difficult to estimate. It is therefore not possible to reliably and accurately control the value of the density of the product entering the hole from the introduced composition due to the decrease in the density in the pipe.

CN 203 212 502 discloses an in situ production facility for explosive products comprising a reel drum with a single pipe for loading a borehole with the explosive product.

Another problem underlying the present invention relates to the implementation of explosive mixing products of different densities during filling according to the depth of the hole or between different holes. In practice, it is advantageous to be able to produce a product of higher density, about 1.2 in the bottom of the hole and a lightened density of about 0.8 at the top of the column. In fact, the downhole is more difficult to destroy and requires more explosive volumetric energy than the upper parts, and an optimal explosion in a borehole than the explosive energy column. On the other hand, the rock mass to be destroyed varies in composition and volume between the borehole and the free surface, depending on the depth and also because of the deviations resulting from the inclination of the substantially cylindrical borehole, and one hole to another due to different inclinations variables from 0 to 25 ° of said holes and the heterogeneity of rock mass composition.

The justification for making an explosive product lower in density is also to reduce the cost of shooting because if the density decreases, it means that there is less mass of product and therefore a lower cost of explosive product.

It is therefore advantageous to be able to adapt the energy of the explosive to the rock mass in a simple way.

US 2003/029346 and WO 97/24298 describe a process for producing explosive products by mixing an emulsion and a gasification reagent. In US 2003/029346 and WO 97/24298 it is mentioned to vary the relative amounts of an emulsion and a gasification reagent in order to vary the density of the mixture obtained. However, in US 2003/029346 the modes of transfer of the explosive product and / or of the two components (emulsion and gasification reagent) are not discussed. In addition, the two components (emulsion and gasification reagent) are hand-mixed in Example 1 or using a spray nozzle Example 2). And in WO 97/24298 a mobile manufacturing unit is described, on which the two components (emulsion and gasification reagent) are separately transferred to a static mixer on board the truck before transferring the explosive product obtained via a single hose to a borehole. This introduction of the two components together (emulsion and gasification reagent) upstream and transfer within a same pipe, however, has the disadvantages explained above.

As a result, in these documents US 2003/029346 and WO 97/24298 , the implementation conditions are not described to enable the density of the final product at the outlet of the transfer line to be changed accurately and reliably in real time. hole being filled without having to purge and / or remove the pipe from the hole.

Indeed, in the prior art, as in US 2003/029346 and WO 97/24298 the production of explosive batches of different densities is not possible without removing the pipe and purging the loading pipe over a long distance of explosive product mixed upstream at a relatively large distance from the hole. According to the standard method, therefore, successive fillings of products having different densities must be made by removing the pipe from the hole and purging it between two filling procedures in the same hole to discharge the explosive product having a different density before producing a product of different density to avoid mixtures of products of different density. This is too time-consuming and therefore can not be realized in practice. Thus, with the device conventionally used, a medium density product 1.2 is produced for all the explosive charge. As a result, there is too much volumetric energy (the product of density and specific energy) consumed in the column, whereas higher explosive energy at the bottom of the hole and lower in height would be preferable.

It is therefore very advantageous to be able to vary the density of the product in the same production cycle in real time in a precise and weak manner.

In WO2008 / 039823 an installation in which the two components are transferred into two separate pipes with a helical outer pipe surrounding the larger diameter central pipe. The downstream end of the small pipe passes through the wall and joins the inside of the larger pipe so that their coaxial down ends open into the same nozzle. Thus one can mix the two components as close as possible to the hole in an external mixing nozzle.

But this embodiment has the following drawbacks. First, this complex helical component pipe is relatively expensive and fragile. In fact, in particular, the outer pipe containing the most dangerous product, namely the gasification reagent, is exposed in the outer part of the pipe which undergoes fatigue and wear due to friction against the walls of the hole, during its winding and unwinding and manipulation in the hole. On the other hand, in practice, it is necessary to regularly shorten the downstream end of the pipe which degrades due to friction in the hole during installation and withdrawal including winding from a winding drum at its upstream end. However, the arrival of the reagent transfer pipe R inside the supply pipe of the matrix M is incompatible with the shortening of the pipe at this position. On the other hand, the gasification reagent must be conveyed over a helical path and therefore over a longer distance of pipe than the straight central pipe of the emulsion because of the helical disposition of the peripheral pipe which requires losses of load and therefore greater pumping force.

Finally, no provision is described in the art WO 2008/039823 to manage the respective amount of base reagent or emulsion or matrix or their intimate mixing in a static mixer that is not exposed in the hole.

FR 2 131 329 discloses a method for facilitating the transfer of a viscous explosive into a cavity by conveying two fluids in coaxial pipes to form a viscous explosive by mixing in a static mixer at its downstream end. In FR 2 131 329 , the pipe is not implemented from a drum on which it is wound at one end and unwound. The feeding and the implementation of coaxial pipes that can be rolled up and unrolled on a drum raise difficulties because of the twisting of said pipes during the windings and unwinding of said pipes on said winder including twists at the parts of the drum. pipes not wound upstream of the drum because these pipe parts are rotated on themselves with respect to said axis of rotation of said drum.

In FR 2 131 329 , it is not mentioned to mix an explosive emulsion with a gasification reagent or a fortiori to vary the density of the mixture obtained continuously and in real time during the deposition and filling of a borehole by controlling the quantities relative reagent and emulsion used.

In WO 2014/123562 not published at the priority date of the present application, there is described an installation and a method in which an emulsion and a gasification reagent are conveyed in a set of two separate pipes but joined together from a winding drum on a truck to a nozzle 90 cooperating with a static mixer 60 disposed outside the downstream end of the pipes at a blast hole to fill explosive product. Complications of twisting of the two pipes are resolved by implementing two pipes joined together over their entire length. On the figure 2 , the small pipe is included in the thickness of the big pipe.

This embodiment has the following disadvantages. First, these pipes joined together over their entire length are relatively expensive and fragile. Indeed, in particular, the small pipe containing the most dangerous product namely the gasification reagent is poorly protected because it is included in the thickness of the large pipe carrying the emulsion. However, this large pipe undergoes fatigue and wear due to friction against the walls of the hole, during its winding and unwinding and manipulation in the hole. On the other hand, the arrival of the reagent transfer pipe at the periphery of the supply pipe of the emulsion matrix requires the implementation of a connection nozzle 90 and a static mixer 60 disposed outside the pipes at their end down and thus constituting metal parts exposed in the hole. However, it is desirable to avoid placing metal parts such as the static mixer inside the hole, which may give rise to shocks with the rock mass of the hole wall which may cause sparks near the priming charge and / or which may contact the detonator wire damaged this one. Finally, no provision is described in WO 2014/123562 to reliably manage the precise variation of the respective amounts of reagent and emulsion base or matrix including output of the small pipe.

• mettre les deux composants en contact optimal l'un avec l'autre pour mélanger au niveau d'un mélangeur statique dans le trou en aval de la conduite de transfert déroulée depuis un tambour enrouleur,
• raccourcir sans difficultés les conduites de transfert lorsque leurs extrémités se dégrade par usure et frottement dans le trou, et
• changer de façon fiable et précise , en temps réel la densité du produit final en cours de chargement et production en sortie de la conduite de transfert dans le trou en cours de remplissage du trou en continu sans avoir à purger et/ou sortir le tuyau du trou, et
• tout en évitant les risques générer par la présence éventuelle de pièce métallique exposée non protégées dans le trou.

The object of the present invention is therefore to provide an improved installation and method for the production of an explosive product comprising the implementation of flexible loading pipes in a hole from a drum on which they are wound which are more suitable and therefore more reliable. , more secure and simpler to implement and implement on the one hand and that allow:

• putting the two components in optimal contact with one another to mix at a static mixer in the hole downstream of the transfer pipe unwound from a drum drum,
• to shorten easily the transfer lines when their ends are degraded by wear and friction in the hole, and
• Reliably and accurately change in real time the density of the end product being loaded and outputting the transfer line into the hole being filled continuously without having to purge and / or remove the pipe from hole, and
• while avoiding the risks generated by the possible presence of unprotected exposed metal part in the hole.

• un premier réservoir contenant la dite matrice à base de dite émulsion explosive, et
• un deuxième réservoir contenant ledit réactif de gazéification, et
• un premier circuit de transfert de dite matrice comprenant au moins un premier tuyau au moins en partie flexible coopérant avec une première pompe et une première vanne, apte à transférer la dite matrice séparément jusqu'à un premier mélangeur, de préférence un premier mélangeur statique, et
• un deuxième circuit de transfert de dit réactif de gazéification comprenant au moins un deuxième tuyau au moins en partie flexible coopérant avec une deuxième pompe et une deuxième vanne, apte à transférer le dit réactif de gazéification séparément jusqu'au dit premier mélangeur, et
• le dit deuxième tuyau est disposé entièrement à l'intérieur du premier tuyau formant un ensemble de tuyaux coaxiaux, ledit premier dispositif de mélange étant disposé à l'intérieur du premier tuyau à son extrémité avale, ledit deuxième tuyau se terminant juste en amont dudit premier mélangeur.

To do this, the present invention provides an installation for producing explosive product in situ by mixing (a) a viscous product, called a matrix, comprising an inverse emulsion of an aqueous phase of oxidant and oily phase of fuel and (b) ) a liquid product containing a chemical compound capable of reacting with the said matrix to increase the explosive character by gasification, called gasification reagent, said installation comprising at least:

• a first reservoir containing said matrix based on said explosive emulsion, and
• a second tank containing said gasification reagent, and
• a first transfer circuit of said matrix comprising at least a first pipe at least partially flexible cooperating with a first pump and a first valve, able to transfer said matrix separately to a first mixer, preferably a first static mixer, and
• a second transfer circuit of said gasification reagent comprising at least a second at least partially flexible pipe cooperating with a second pump and a second valve, able to transfer said gasification reagent separately to said first mixer, and
• said second pipe is disposed entirely inside the first pipe forming a set of coaxial pipes, said first mixing device being disposed inside the first pipe at its downstream end, said second pipe ending just upstream of said first pipe; mixer.

It is understood that the outer diameter of said second pipe is smaller than the internal diameter of said first pipe so that said matrix is conveyed without contact with the gasification reagent, in the annular space between the two pipes on the one hand, and on the other hand, the matrix flow makes it possible to dispose the second pipe substantially coaxially with the first pipe without the need for a centralizer, the gasification reagent being conveyed separately without contact with the matrix until it opens into the static mixer in which an intimate mixture of the two products is produced to produce the explosive product at the outlet of the static mixer at the downstream end of the first pipe.

In the present description, the term "upstream" and "downstream", the position in reference to the flow direction of the fluids in the pipes from the tanks to the first mixer and to the outlet opening into the dispensing hole of the product. explosive at the output of the first mixer.

It is understood that in operation the downstream end of the coaxial pipe assembly is inserted into a hole to be filled with explosive material exiting said first mixer.

Thus, on the one hand, only the first pipe is in contact with the outside and in particular the walls of the hole during operations protecting the other equipment and in particular avoiding damage to the detonator wire, among others; and, on the other hand, by controlling the relative flow rates of the matrix and the gasification reagent, controlling in almost real time the density of the explosive product obtained, as the hole is filled continuously and thus varying the density of the product. explosive product, namely its explosive power according to the depth at which it is arranged in the hole or from one hole to another in different holes as explained below in connection with the method according to the invention.

The term "static mixer" is understood herein to mean, in a manner known to those skilled in the art, a device containing mechanical elements able to create a modification in the movement of a moving fluid traveling through it creating vortex movements allowing the mixing without adding energy to move said mechanical elements other than that provided by the movement of the fluid. Most often the static mixers consist of a tube containing one or more three-dimensional structures favoring the appearance of vortices during the passage of a flow of fluid in the longitudinal direction of the tube.

More particularly, the coaxial pipe assembly is connected to a reel drum, and is at least partially or coactably wound on said reel drum, the downstream end of the coaxial pipe assembly being disposed in or out of above an explosion hole, preferably a substantially cylindrical borehole having placed an explosive charge and a detonator connected to the surface by a detonator wire.

Typically, a reel drum of 30 to 80 cm in diameter is used for 10 turns of winding of pipes 30 to 100m long with external diameters of first pipe of 30 to 50mm and internal diameters of 25 to 40mm and external diameters. second pipe from 5 to 15 mm with an internal diameter of 3 to 10mm.

• un premier orifice d'entrée, formant une ouverture amont dudit manchon et disposée axialement dans une direction longitudinale (XX') la paroi cylindrique dudit manchon, ledit premier orifice d'entrée étant relié à une partie, de préférence une partie rigide, du dit premier circuit de transfert de dite matrice, et
• un deuxième orifice d'entrée, disposé latéralement au niveau de la paroi cylindrique dudit manchon, formant une ouverture amont de la dite pièce coudée traversant la paroi cylindrique dudit manchon et disposée perpendiculairement à la dite direction longitudinale (XX'), ledit deuxième orifice d'entrée étant relié à une partie, de préférence une partie rigide, du dit deuxième circuit de transfert de dit réactif de gazéification, et

• un premier orifice de sortie, formant une ouverture avale dudit manchon et disposée axialement dans ladite direction longitudinale (XX') de la paroi cylindrique dudit manchon, ledit premier orifice de sortie étant relié par un premier raccord à joints tournants à l'extrémité amont d'une partie rigide dudit premier tuyau en amont d'un dit tambour enrouleur, et
• un deuxième orifice de sortie, disposé axialement dans ladite direction longitudinale (XX') de la paroi cylindrique dudit manchon, formant une ouverture avale de la dite pièce coudée à l'intérieur dudit manchon, ledit deuxième orifice de sortie étant relié par un deuxième raccord à joints tournants à l'extrémité amont du dit deuxième tuyau de transfert de dit réactif de gazéification.

According to the present invention, said first and second pipes are connected coaxially to each other at their upstream ends by a first connecting piece comprising a sleeve with an external cylindrical wall and an internal bent piece, said first connecting piece. preferably being integral with a winding drum on which is winded at least in part or able to be wound up said set of coaxial pipes, said first connecting piece comprising:

• a first inlet orifice, forming an upstream opening of said sleeve and arranged axially in a longitudinal direction (XX '), the cylindrical wall of said sleeve, said first inlet orifice being connected to a part, preferably a rigid part, of said first transfer circuit of said matrix, and
• a second inlet orifice, disposed laterally at the level of the cylindrical wall of said sleeve, forming an upstream opening of said bent piece passing through the cylindrical wall of said sleeve and disposed perpendicular to said longitudinal direction (XX '), said second orifice entry being connected to a part, preferably a rigid portion of said second transfer circuit of said gasification reagent, and

• a first outlet opening, forming an opening downstream of said sleeve and arranged axially in said longitudinal direction (XX ') of the cylindrical wall of said sleeve, said first outlet orifice being connected by a first rotary joint connection to the upstream end of said sleeve; a rigid portion of said first pipe upstream of a said winding drum, and
• a second outlet orifice, arranged axially in said longitudinal direction (XX ') of the cylindrical wall of said sleeve, forming an opening downstream of said bent piece inside said sleeve, said second outlet orifice being connected by a second coupling with rotating joints at the upstream end of said second transfer pipe of said gasification reagent.

It will be understood that, upstream of said first connecting piece, said first and second circuits are separated and extend from said first and second reservoirs in different directions and said first part provides the coaxial connection of the first and second two pipes downstream thereof, the two flows of said matrix and said reagent, however, remaining separated to the first mixer. Said first pipe or outer pipe is secured to said second pipe or inner pipe only at a connecting piece and supply upstream of said drum described above.

According to the present invention, the attachment of the upstream ends of said first and second pipes to said first and second outlets of said first connecting piece is via two first and second rotary joint couplings each allowing separately the rotation on itself with respect to said longitudinal axis (XX ') of the upstream ends of said first and second pipes respectively, said first connecting piece and said rotary joint fittings being arranged upstream a said winding drum so that said first and second outlet orifices are arranged in the axis of rotation XX 'of said drum.

This feature is particularly advantageous because it avoids twisting of said first and second pipes during the winding and unwinding of said pipes on said winder when the upstream uncoiled portions of said pipes are rotated on itself relative to said axis of rotation said drum in a differentiated manner.

Fittings of the type referred to as "rotary joint coupling" are well known to those skilled in the art, and consist essentially of two parts interconnected by O-rings and sets of ball bearings allowing the rotary movement of one of them relative to the other about a common axis, each part being adapted to be connected to a separate element. Here, it is a tubular connecting piece adapted to be connected to tubular elements.

It is understood that the fixing of the ends of the various pipes on said first connecting piece, possibly on said joints with rotating joints, is via rigid connection.

More particularly, said second pipe comprises at its end downstream, inside said first pipe, a valve adapted to open and let the flow of said gasification reagent under the pressure of said flow when the second pump is actuated and able to remain closed and prevent gasification reagent leakage when the second pump is deactivated.

This characteristic is important to allow a reliable and accurate control of the variation in real time during filling of the hole of the density of the explosive product obtained by mixing said matrix and said gasification reagent.

• le dit premier tuyau comprend au moins une partie rigide coudée de premier tuyaux assemblée à une partie flexible de premier tuyau de manière étanche et réversible par un collier, ladite partie rigide coudée s'étendant en partie en amont du dit tambour et étant solidaire de celui-ci et apte à être entrainée en rotation autour de l'axe de rotation dudit tambour lorsque ledit tambour est actionné en rotation, ladite partie flexible de premier tuyau étant apte à être enroulée autour du dit tambour, et
• ledit deuxième tuyau comprend deux parties flexibles reliées entre elles par un raccord étanche et réversible rigide du type à union double, la partie flexible de dit deuxième tuyau disposée en amont du dit raccord du type union double étant plus courte que la partie flexible de dit deuxième tuyau disposée en aval, ledit raccord du type à union double étant disposée au niveau du dit tambour ou en amont de celui-ci, de préférence à proximité du dit collier.

More particularly, according to other characteristics:

• said first pipe comprises at least a bent rigid portion of first pipe joined to a flexible portion of first pipe sealingly and reversibly by a collar, said bent rigid portion extending in part upstream of said drum and being integral with that and able to be rotated about the axis of rotation of said drum when said drum is actuated in rotation, said flexible portion of first pipe being able to be wound around said drum, and
• said second pipe comprises two flexible parts connected together by a rigid and reversible connection of the double union type, the flexible portion of said second pipe disposed upstream of said double union type being shorter than the flexible portion of said second pipe disposed downstream, said double union type connection being disposed at or upstream of said drum, preferably close to said collar.

Thus, when it is desired to shorten said second pipe due to the shortening made at the downstream end of the first pipe when it is worn and damaged, it is easy to open the first pipe at the said collar upstream. drum, unwind the set of coaxial pipes, and take out the downstream portion of said second pipe to shorten it; and this without having to uncouple the upstream portion of the second flexible pipe at the joint with rotating joint and out of said first mixer.

One can also - when one wants to operate an installation without variation of density - completely leave the second pipe, shut off said second, inlet orifice and connect a bypass of the second circuit of arrival of gasification reagent on the said first circuit upstream of a second mixer upstream of said drum. In this case, there is no more coaxial circulation of matrix and gasification reagent.

Connections of the type called "double union" are well known to those skilled in the art, and consist essentially of the assembly of at least three pairs of male / female connection parts operating by removable links.

More particularly, a hollow tubular abutment having a longitudinal central opening is removably disposed at the downstream end of the first pipe for retaining said first mixer within the first pipe allowing the explosive product to pass through the central opening of the first pipe. said stop, a thread on a cylindrical outer wall for screwing and thus removably fix said abutment against the inner wall of said first pipe, preferably using a screw wrench adapted to cooperate with the end swallowing said longitudinal central opening to screw inside said first pipe or unscrew said stop to remove it from said first pipe.

This feature makes it possible to protect the static mixer and especially to be able to easily remove it to cut the downstream end of the first hose when it is damaged or worn, before reintroducing said first mixer then said stop.

More particularly, according to an original feature of the invention, said first mixer is a static mixer comprising a plurality of fins each having a helical surface, preferably extending in its axial direction over a length corresponding to a pitch of the corresponding helical curve, said helical surfaces being supported by a same reinforcing rod to which they are attached juxtaposed in the longitudinal direction of said first pipe, said successive helical surfaces being angularly offset in rotation with respect to their common virtual axis of helical surface substantially coinciding with a longitudinal axis of said first pipe coaxial axis with said first pipe, the diameter of said helical surfaces being substantially identical or just sufficiently lower than internal diameter of the first pipe to allow the rotation of said fins under the effect of the pressure of the flow of matrix and reagent mixed through them.

This type of mixer manufactured according to the invention is more mechanically reliable and more efficient in the implementation conditions according to the invention.

More particularly, an automated central control and control unit comprising electronic means controlled by software with a keyboard / or graphical interface, makes it possible to control and control the respective quantities and flow rates of said matrix and / or preferably said gasification reagent. and varying the density of the explosive product obtained by controlling and controlling first and / or second valves and / or controlling the speeds of said first and / or second pumps, preferably said central unit being supported on a motor vehicle, more preferably said vehicle supporting said first and second tanks and said first and second pumps.

1. 1) on transfère un produit visqueux de dite matrice, et un produit liquide de dit réactif de gazéification, dans des dits premier et respectivement deuxième tuyaux coaxiaux, et
2. 2) on mélange la dite matrice et le dit réactif de gazéification dans un dit premier mélangeur, et
3. 3) on dépose ledit produit explosif en sortie du dit premier mélangeur, dans un trou pour explosion, de préférence un trou de forage sensiblement cylindrique dans lequel on a précédemment placé une charge d'amorçage d'explosif et un détonateur relié à un fil de détonateur remontant en surface.

The present invention also provides a method for producing an explosive product in situ using an installation according to the invention comprising the steps in which:

1. 1) transferring a viscous product of said matrix, and a liquid product of said gasification reagent, into said first and second coaxial pipes, and
2. 2) mixing said matrix and said gasification reagent in a said first mixer, and
3. 3) depositing said explosive product at the outlet of said first mixer, in an explosion hole, preferably a substantially cylindrical borehole in which an explosive initiation charge and a detonator connected to a lead wire have previously been placed; detonator rising to the surface.

The process according to the invention makes it possible to vary the respective proportions of gasification reagent and emulsion matrix entering the mixer in order to change in real time the density of the product arriving in the hole during a single filling procedure. . This is made possible, inter alia, by the fact that reagents R and matrix M are brought into contact just before the mixer and that the explosive product deposited in the hole exits directly from said mixer. It is thus possible, according to the invention, to automatically adapt the energy of the explosive to the rock mass in a simple manner by making a single filling of explosive continuously or in the same production cycle, a single sequence of Pumping explosive, a single continuous sequence means here that the dispensing pipe is placed in the hole, then actuates the transfer pump and deposits and spring the pipe after filling the hole to the desired level.

If the hole is deep, the pipe can be removed gradually as the hole is filled by wrapping the pipe on the drum.

The method according to the invention therefore makes it possible to modify, almost in real time, the density of the product and therefore the mass energy of the explosive, the latter being inversely proportional to its density, and more particularly to varying the density of the explosive. product allows to have a high density, in the bottom of the hole and a lightened density in the column in height.

Typically, holes 5 to 30 m deep and 5 cm to 20 cm in diameter are formed, and at least two, preferably 4, amounts of explosive product are defined for 4 density values corresponding to mass energies of 2 to 5 MJ. / kg (10 ⁶ J / kg), in particular densities of 0.5 to 1.5.

In practice the quantity of explosive product corresponds substantially to the quantity of said matrix because the relative amount of reagent is of the order of 0.1 to 2% only relative to the weight of explosive product obtained.

More particularly, the quantities and flow rates of said matrix and of said gasification reagent are controlled and controlled so as to produce an explosive product of determined value density at the outlet of the first mixer.

More particularly, the density of the explosive product obtained during filling is varied according to the quantity of explosive product deposited and / or the depth at which the explosive product is deposited in the same hole or from one hole to another in different holes.

More particularly, selected quantities of explosive products having different specific density values are respectively selected and controlled to be successively deposited in a hole being filled, preferably continuously.

Preferably, one chooses from a plurality of predetermined density values corresponding to mass explosive energies of 2 to 5 MJ / Kg (10 ⁶ J / Kg), preferably densities between 0.5 and 1.5.

In practice the amount of explosive product substantially corresponds to the amount of said matrix in the relative amount of reagent is of the order of 0.1 to 2%.

Typically, for holes 5 to 30 m deep and 5 cm to 20 cm in diameter, 4 quantities of explosive product are defined for 4 density values from 0.8 to 1.2.

More particularly, in step 1), the said matrix and said gasification reagent are separately transferred from said first and second reservoirs respectively into first pipe and respectively second pipe cooperating with a first pump and a first valve and respectively a second pump and a second valve, and controlling and controlling a constant flow of said matrix by controlling the speed of the first pump and / or the opening of said first valve, and the flow rate of said gasification reagent is varied by controlling the speed of the second pump and / or the opening of said second valve.

More particularly, a constant flow rate of said matrix is controlled and controlled by controlling the speed of the first pump using a speed sensor of said first pump, and the flow rate of said gasification reagent is varied at controlling the speed of the second pump using a flow meter.

Indeed, in a manner known to those skilled in the art, abacuses allow for a given density value, the respective rates of gasification reagent y and said matrix x vary linearly according to a formula y = ax + b. The values of a and b depend on the composition of said porosity reactants and said matrix. Charts provide graphs of said reactant flow rates in L / min relative to flow values of said matrix in Kg / min. Thus, for a set d matrix rate value, it is sufficient to vary the rate of gasification reagent.

On the other hand, because the viscous product is more difficult to control and it is easier to vary and control the flow rate of a liquid fluid, it is advantageous to work with a constant matrix flow and to vary the flow rate of gasification reagent.

• une dite matrice de densité de 1 à 1.7 d'une émulsion de base dite inverse ou « eau dans huile » obtenue par un mélange de (a) une phase continue organique, constituée mélange d'huiles minérales et gasoil, et (b) une phase aqueuse discontinue de divers sels comburants en solution aqueuse à base de nitrate d'ammonium et/ou nitrate de sodium et/ou nitrate de calcium, à un débit de 25 à 300 Kg/min. (min.=minute), de préférence de 100 à 150 kg/min., et
• une solution dit réactif de gazéification de densité de 0.5 à 1.5 à base de nitrite de sodium et/ou thiocyanate de sodium, à un débit de 0.1 à 2 L/min ;
• dans un ratio de débit de réactif/ matrice variant de de 0.1 à 2 L/ 100Kg de la proportion.

Typically; in practice, to produce an explosive product with a density of 0.5 to 1.5, the following is used:

• a said density matrix of 1 to 1.7 of a so-called inverse base emulsion or "water in oil" obtained by a mixture of (a) an organic continuous phase, constituted mixture of mineral oils and gas oil, and (b) a aqueous discontinuous phase of various oxidizing salts in aqueous solution based on ammonium nitrate and / or nitrate sodium and / or calcium nitrate at a rate of 25 to 300 Kg / min. (min = minute), preferably from 100 to 150 kg / min., and
• a so-called gaseous reactant solution with a density of 0.5 to 1.5 based on sodium nitrite and / or sodium thiocyanate, at a flow rate of 0.1 to 2 L / min;
• in a reagent / matrix flow ratio ranging from 0.1 to 2 L / 100Kg of the proportion.

1. a) on retire le dit premier mélangeur du dit premier tuyau,
2. b) on coupe l'extrémité avale du premier tuyau usée et/ou endommagée,
3. c) on replace le dit premier mélangeur à l'intérieur du dit premier tuyau,
4. d) on désassemble l'extrémité amont de la partie flexible du dit premier tuyau, et on extrait une partie amont du dit deuxième tuyau et on désassemble une première partie amont de deuxième partie avale de deuxième tuyau flexible, et
5. e) on sort du premier tuyau et on raccourcit la dite deuxième partie avale de deuxième tuyau flexible, puis on la replace dans le dit premier tuyau et on la raccorde à nouveau à la partie amont du deuxième tuyau restée à l'intérieur d'une partie amont rigide du premier tuyau.

More particularly, when the downstream end of the first pipe is worn and / or damaged, the following steps are carried out:

1. a) said first mixer is removed from said first pipe,
2. b) cutting the downstream end of the first worn and / or damaged pipe,
3. c) replacing said first mixer within said first pipe,
4. d) disassembling the upstream end of the flexible portion of said first pipe, and extracting an upstream portion of said second pipe and disassembling a first upstream portion of second downstream portion of second flexible pipe, and
5. e) exiting the first pipe and shortening said second downstream portion of the second flexible pipe, then replacing it in said first pipe and reconnecting it to the upstream portion of the second pipe remained inside a rigid upstream part of the first pipe.

• la figure 1 représente une unité mobile de fabrication d'explosifs 1 (abrégée « UMFE ») à savoir un camion 1 transportant le matériel de l'installation selon la présente invention sur son châssis arrière 1a, et
• la figure 1A représente le déploiement d'un ensemble de tuyaux coaxiaux 6 déroulés depuis un enrouleur 5 à l'arrière dudit camion, et
• la figure 1B représente une vue en coupe d'un trou de forage 11 réalisé dans un massif rocheux 15 dans lequel est déposé du produit explosif 10, l'extrémité avale ouverte de l'ensemble de tuyaux coaxiaux 6 selon l'invention disposée dans le trou, et
• la figure 2 représente un schéma de montage des matériels de l'installation selon la présente invention en vue de la mise en oeuvre du procédé selon l'invention, et
• la figure 3 représente le détail d'une vue en perspective de l'enrouleur 5, et
• la figure 3A représente une vue en coupe verticale au niveau de la première partie rigide 6₁a du tuyau externe 6₁ de l'ensemble de tuyaux coaxiaux 6, et
• les figures 4A et 4B sont des vues en coupe d'une dite première pièce de connexion 3 et ensemble de deux raccords à joints tournants 4₁ et 4₂, et
• la figure 4C est une vue montrant le montage dudit deuxième tuyau ou tuyau interne de transfert de réactif de gazéification 6₂ sur ladite première pièce de connexion 3 et le deuxième raccord à joint tournant 4₂, et
• les figures 5A, 5B et 5C représentent différentes vues relatives à l'introduction du premier mélangeur statique 7 à l'intérieur et à l'extrémité avale du premier tuyau 6₁ en aval du clapet 6₄ de l'extrémité avale 6₄ du deuxième tuyau 6₂.

Other characteristics and advantages of the present invention will emerge more clearly on reading the following description, given in an illustrative and nonlimiting manner, with reference to the appended drawings in which:

• the figure 1 represents a mobile explosive manufacturing unit 1 (abbreviated "UMFE"), namely a truck 1 carrying the equipment of the installation according to the present invention on its rear chassis 1a, and
• the Figure 1A represents the deployment of a set of coaxial pipes 6 unwound from a reel 5 at the rear of said truck, and
• the Figure 1B represents a sectional view of a borehole 11 made in a rock mass 15 in which explosive product 10 is deposited, the open downstream end of the set of coaxial pipes 6 according to the invention disposed in the hole, and
• the figure 2 represents a circuit diagram of the equipment of the installation according to the present invention with a view to implementing the method according to the invention, and
• the figure 3 represents the detail of a perspective view of the winder 5, and
• the figure 3A shows a vertical sectional view at the first rigid section 6 ₁ a of the outer pipe 6 ₁ of assembly of coaxial pipes 6, and
• the Figures 4A and 4B are cross-sectional views of a said first connecting piece 3 and a set of two joints with rotating joints 4 ₁ and 4 ₂ , and
• the figure 4C is a view showing the mounting of said second internal gasification reagent transfer pipe 6 or pipe ₂ to said first connecting piece 3 and the second rotating joint fitting 4 ₂ , and
• the FIGS. 5A, 5B and 5C represent different views relating to the introduction of the first static mixer 7 inside and at the downstream end of the first pipe 6 ₁ downstream of the valve 6 ₄ of the downstream end 6 ₄ of the second pipe 6 ₂ .

detailed description

• un camion 1 supporte sur son châssis arrière la un premier réservoir 1-1 contenant un produit constitué principalement d'une émulsion explosive dénommée « matrice », et
• un deuxième réservoir 1-2 contenant un réactif de gazéification notamment à base de nitrite de sodium et de thiocyanate, et
• un troisième réservoir 1-3 contenant un catalyseur de réaction, à savoir un acide notamment de l'acide acétique et destiné à catalyser la réaction de la matrice avec le réactif de gazéification pour dégager un gaz comme décrit ci-après, et
• un quatrième réservoir d'eau 1-4, et
• un cinquième réservoir de nitrates 1-5.

A facility 1 for producing explosive products in situ, that is to say at the site of use of the explosive, namely, more precisely at a borehole 11 according to the invention, comprises the following equipment arranged as follows:

• a truck 1 supports on its rear chassis the first tank 1-1 containing a product consisting mainly of an explosive emulsion called "matrix", and
• a second tank 1-2 containing a gasification reagent especially based on sodium nitrite and thiocyanate, and
• a third reservoir 1-3 containing a reaction catalyst, namely an acid including acetic acid and intended to catalyze the reaction of the matrix with the gasification reagent to release a gas as described below, and
• a fourth water tank 1-4, and
• a fifth tank of nitrates 1-5.

• une première pompe 2-1 disposée en sortie du premier réservoir 1-1 et destinée à transférer la matrice du premier réservoir 1-1 vers le trou de forage 11 par l'intermédiaire d'un premier circuit comprenant une canalisation de transfert de matrice la puis un ensemble de tuyaux coaxiaux 6 décrit ci-après, et
• une deuxième pompe 2-2 disposée en sortie du deuxième réservoir 1-2 destinée à transférer le réactif de gazéification depuis son deuxième réservoir 1-2 dans un deuxième circuit comprenant une canalisation de transfert de réactif 1b vers l'ensemble de tuyaux coaxiaux 6 tel que décrit ci-après, et
• une troisième pompe 2-3 destinée à transférer le catalyseur depuis son réservoir 1-3 jusque dans le premier réservoir 1-1, et
• une pompe 2-5 et/ou vis d'extraction destinée à transférer le nitrate du cinquième réservoir 1-5 vers ledit premier réservoir 2-1
• une pompe 2-4 destinée à transférer l'eau du quatrième réservoir 1-4 dans un circuit 1c vers le premier circuit la de transfert de la matrice de façon à lubrifier le produit visqueux que constitue la matrice et faciliter son transfert au sein d'un premier tuyau de transfert 6₁ comme décrit ci-après.

The truck 1 also supports on its chassis the following different pumps:

• a first pump 2-1 disposed at the outlet of the first reservoir 1-1 and intended to transfer the matrix of the first reservoir 1-1 towards the borehole 11 via a first circuit comprising a matrix transfer pipe the then a set of coaxial pipes 6 described below, and
• a second pump 2-2 disposed at the outlet of the second reservoir 1-2 intended to transfer the gasification reagent from its second reservoir 1-2 into a second circuit comprising a reagent transfer line 1b towards the set of coaxial pipes 6 such as described below, and
• a third pump 2-3 for transferring the catalyst from its reservoir 1-3 into the first reservoir 1-1, and
• a pump 2-5 and / or extraction screw for transferring the nitrate of the fifth reservoir 1-5 to said first reservoir 2-1
• a pump 2-4 for transferring water from the fourth reservoir 1-4 in a circuit 1c to the first transfer circuit 1a of the matrix so as to lubricate the viscous product constituted by the matrix and facilitate its transfer within a first transfer pipe 6 _1, as described below.

The junction of the water circuit 1c on the first matrix circuit la is by a piece 1d called "lubrication water injector ring". The function of the water is only the lubrication of the matrix for a reduction of the losses of charges.

The pipe constituting a first matrix transfer circuit connects the first tank 1-1 to a first external flexible pipe 6 ₁ of the pipe assembly 6 wound on a winder 5. And, the second gasification reagent transfer circuit 1b comprises pipes from the second reservoir 1-2 to a second internal gasification reagent transfer pipe 6 ₂ of the pipe assembly 6 wound on the reel 5. The second pipe 6 ₂ is disposed at the inside of the first pipe 6 ₁ and is positioned substantially coaxially inside the pipe 6 ₁ when due to the flow of matrix passing in the annular space between the first pipe 6 ₁ and the second pipe 6 ₂ when one transfers said matrix to the borehole 11.

The truck 1 also supports a static mixer called "second mixer" static 2-6, upstream of the coaxial pipe assembly 6.

• une première vanne V1 en sortie du réservoir 1-1 monté sur la première canalisation la de transfert de matrice, et
• en aval de la première pompe 2-1, une deuxième vanne V2 en sortie du deuxième réservoir 1-2 de transfert de réactif de gazéification coopérant avec le deuxième circuit 1b de transfert de réactif de gazéification en amont de la deuxième pompe 2-2, et
• une vanne d'isolement 1-2a en amont du deuxième réservoir de réactif de gazéification 1-2, et
• une troisième vanne V3, vanne trois voies permettant d'alimenter une canalisation de dérivation 1b-1 du deuxième circuit 1b de réactif de gazéification connecté à la première canalisation de transfert de matrice la en aval de la première vanne V1 mais en amont dudit deuxième mélangeur statique 2-6.

The truck 1 also supports on its rear chassis the valves comprising:

• a first valve V1 at the outlet of the tank 1-1 mounted on the first channel of transfer matrix, and
• downstream of the first pump 2-1, a second valve V2 at the outlet of the second gasification reagent transfer tank 1-2 cooperating with the second gasification reagent transfer circuit 1b upstream of the second pump 2-2, and
• an isolation valve 1-2a upstream of the second gasification reagent tank 1-2, and
• a third valve V3, a three-way valve for supplying a bypass line 1b-1 of the second gasification reagent circuit 1b connected to the first matrix transfer line 1a downstream of the first valve V1 but upstream of said second mixer static 2-6.

Upstream of the second mixer 2-6 is connected an air injection bypass 1e, joining the first circuit of the matrix downstream of the first valve V1. It is thus possible by sending compressed air, clean the entire circuit downstream, at will, especially between two uses.

The truck 1 also supports on its rear chassis the central control unit 9 comprising a keyboard 9a and / or a graphic interface 9b, cooperating with software capable of controlling the actuation of said pumps and said valves.

Downstream of the third valve V3, the gasification reagent transfer circuit 1b joins the first matrix transfer circuit 1a downstream of the second mixer 2-6 at a connecting part called the first connection piece 3 which ensures the connection between the first pipe 1a and the second pipe 1b just upstream of the set of coaxial pipes 6 wound on the winder 5, so that the flow of gasification reagent is transferred into the second inner pipe 6 ₂ and the matrix flow from the first circuit is transferred inside the first pipe 6 ₁ and outside the second pipe 6 ₂ in the annular space between the inner wall of the first pipe ₁ and the second pipe 6 ₂ , as described below.

The valve V3 makes it possible, by forcing the circulation of the gasification reagent to the bypass 1b-1, to obtain a first operating mode of the installation according to a traditional method in which the gasification reagent and the matrix are mixed within the mixer. 2-6 upstream of the set of transfer pipes 6 to the borehole 11. In this traditional embodiment, the explosive product 10 produced within the mixer 2-6 is conveyed over a long distance, that is to say all along a long pipe joining the borehole 11.

• en aval de la deuxième pompe 2-2, un débitmètre 2-2a du type à section variable, tel que commercialisé par la société KROHNE (FR) sous la référence H250/RR/MXX/ESK, la deuxième pompe 2-2 étant du type à piston notamment telle que commercialisée par la société CAT PUMPS (USA) sous la référence CAT2XX, et
• un capteur de vitesse 2-1a du type compte tours monté sur le moteur hydraulique de la pompe tel que commercialisé par la société DANFOSS (FR) sous la référence 151-5662 indiquant la vitesse de rotation de la première pompe 2-1, la première pompe 2-1 étant une pompe volumétrique dite à cavité progressive entraînée par un moteur hydraulique du type commercialisé par la société DANFOSS sous la référence par exemple OMS160EM151F-3023. Plus particulièrement, La pompe envoie des signaux pulsés selon un nombre déterminé connu d'impulsion par tour au capteur de vitesse 2-1a de sorte qu'on peut connaître la quantité de produit débité par la pompe, par étalonnage en fonction du nombre de tours de ladite première pompe.

The chassis 1 of the truck 1 also supports a 2-5 filter upstream of the second pump 2-2 and downstream of the second reservoir 1-2. In addition, the chassis also supports it:

• downstream of the second pump 2-2, a flowmeter 2-2a of the variable-section type, as sold by the company KROHNE (FR) under the reference H250 / RR / MXX / ESK, the second pump 2-2 being piston type in particular as sold by the company CAT PUMPS (USA) under the reference CAT2XX, and
• a speed sensor 2-1a of revolving type mounted on the hydraulic motor of the pump as marketed by the company DANFOSS (FR) under the reference 151-5662 indicating the speed of rotation of the first pump 2-1, the first 2-1 pump being a so-called progressive cavity volumetric pump driven by a hydraulic motor of the type sold by DANFOSS under the reference for example OMS160EM151F-3023. More particularly, the pump sends pulsed signals according to a known determined number of pulses per revolution to the speed sensor 2-1a so that the quantity of product delivered by the pump can be known by calibration according to the number of revolutions of said first pump.

Downstream of the first pump 2-1, are also mounted on the first circuit 1-a different sensors namely, a matrix fluid pressure sensor 1a-1, a temperature sensor 1a-2, and a detection sensor no flow rate of matrix flow 1a-3. In fact, the pressure of the matrix flow in the pipe 1a must not exceed 20 bars and the temperature must remain below 70 ° C for safety reasons, at the risk that the explosive emulsion becomes too sensitive. Indeed, the explosive emulsion becomes more sensitive to rapid decomposition when the pressure and the temperature increase. To better understand this risk, the limit pressure of 20bar was determined using a specific safety device called MBP ("Minimum Burning Pressure").

A device 2-2b cooperating with the second pump 2-2 is a safety valve used to lower the pressure when the pressure is above a threshold level.

According to an original feature of the present invention, a second gasification reagent transfer pipe is disposed within a first die transfer pipe 6-1, to form a pipe assembly 6 according to the following arrangement.

The two independent matrix transfer pipelines 1a and gasification reagent transfer 1b meet at a first original connection piece 3 according to the present invention described in FIGS. Figures 4A, 4B and 4C .

The first connecting part 3 comprises a main sleeve outer cylindrical wall 3a open at its upstream ends and downstream 3 ₁ a 3 _1b thereby forming a first inlet port 3 ₁ a circular section upstream and a first outlet port 3 ₁ b downstream with circular section, both arranged along a longitudinal axis XX 'of said casing 3a corresponding to the axis of rotation of the drum 5.

The first inlet port 3 ₁ a has a thread 3 ₃ a so that the threaded end of a fitting threaded 1a ₁ to the downstream end of the The first matrix transfer line can be fixed by screwing.

In downstream end of the first connecting part 3 the upstream end of the first pipe 6 ₁ and the upstream end of second pipe 6 ₂ are mounted coaxially on the first outlet port 3 _1b and respectively second output port 3 b ₂ coaxial to the downstream end of said first connecting part 3 via a first coupling rotary joint 4 ₁ and respectively a second coupling rotating joint 4 _2.

The first output port 3 _1b includes a threaded external surface 3 ₃ b on the outer surface of the downstream end of the wall of cylindrical casing 3a which can be screwed into the female end of a first coupling rotary joint 4 _1, whose downstream end comprises an external peripheral thread 4 ₁ c on which will be screwed a female connector 6 ₁ d at the upstream end of a first rigid portion 6-1a of the first pipe 6 ₁ .

On the Figure 4B the known structure of this type of first rotary joint coupling 4 ₁ having O-ring seals 4 ₁ d and ball bearings 4 ₁ e is shown to ensure the cooperation between two tubular parts 4 ₁ a and 4 ₁ b juxtaposed in the axial direction XX '. Said first part 4 ₁ a has an upstream socket end screwed onto the external thread 3 b ₃ of the male end of the part 3 forming the first outlet port 3 _1b. A second part 4 ₁ b of the first swivel joint connection 4 ₁ comprises at its downstream end, the external thread 4 ₁ c cooperating with the end connector 6 ₁ d of the first pipe 6 ₁ .

The ball bearings 4 ₁ e and o-rings 4 ₁ d allow the rotation of the first rotary part 4 ₁ b of the first rotary joint connection 4 ₁ around the common axis XX 'of the first connecting piece 3 and the rotating joint 4 ₁ relative to the first part 4 ₁ a fixed rotary joint connection 4 _1. Thus, the upstream end of the first pipe 6 ₁ can turn on itself in case of torsion during its winding on the reel 5 as described below.

The casing wall 3a contains an internal angle piece 3b having a first tubular portion extending in a direction perpendicular to the longitudinal axis XX 'of the wall 3a and defining a second inlet port 3 ₂ a passing through said wall 3a and on which is screwed the threaded end of a terminal connection 1b 'of the second gasification reagent supply line 1b.

The bent piece 3b also comprises a tubular part arranged axially in the interior of the workpiece 3 and forming a second output port 3 _2b onto which is screwed a first upstream fixed part ₂ to 4 of a second coupling rotating seal 4 ₂ comprising a second part swallows 4 ₂ b rotatably juxtaposed in the axial longitudinal direction XX '. Said first upstream February ₄ piece cooperates with the second part swallows 4 _2b by seals and bearings (not shown), allowing rotation of said second part 4 _2b of the second rotary joint to connection 4 ₂ about the XX axis. The upstream end of the second pipe 6 ₂ is fixed to said second rotatable member 4 _2b of the second coupling rotary joint 4 _2, via an end connector piece 6 ₂ tbsp.

It is possible to use rotary joint fittings of reference TP 1100M / F marketed by PACQUET INDUSTRIE (France).

The first connecting piece 3 and the two joints with rotating joints 4 ₁ and 4 ₂ are arranged just upstream of a drum drum 5 supported by a structure or beam 5a. On the winding drum 5, is wound a flexible downstream portion 6 _1b of the first pipe 6 ₁ connected to an upstream rigid portion 6 ₁ by a removable collar 6 ₁ c.

The upstream rigid portion 6 _1a of the first pipe 6 ₁ integral with both of the first connecting piece 3 via the first rotary joint connection 4 ₁ and also integral with the winding drum 5 is thus rotated with the winding drum 5 around it of the axis of common rotation XX 'of the drum winder 5 and said joints with rotating joint 4 ₁ and 4 ₂ and the connection piece 3.

The rigid part 6 ₁ has different bends, so that its upstream part (upstream of the drum) is arranged in the axial direction XX 'of the first connection piece 3 while its downstream part at the collar 6 ₁ c is disposed in a tangential direction of a cylindrical portion 5-1 of the winding drum 5 and follows the curve of said cylindrical portion of the drum on which can be wound the second flexible part 6 _1b of the first pipe 6 when ₁ actuates rotating the drum winder 5.

The second pipe 6 ₂ disposed inside the first pipe 6 ₁ comprises two flexible parts 6 ₂ a and 6 ₂ b interconnected by a double union connection 6 ₃ . This double union connection 6 ₃ is of the type well known to those skilled in the art such as for example a reference double union connection SS-400-6 marketed by the company SWAGELOK (USA) also called under the name "Tube fitting". This type of double union connection 6 ₃ cooperates with end connection pieces 6 ₂ d and 6 ₂ e at the ends respectively of the first upstream flexible parts 6 ₂ a and downstream 6 ₂ b of the second pipe 6 ₂ . Fitting dual-law status 6 ₃ is disposed just downstream of the collar 6 ₁ c so that when opening and / or removing the collar 6 ₁ c to separate the two parts of the first pipe 6 and 6 _{1a 1b,} we can extract the second pipe 6 ₂ and uncouple the two parts 6 and 6 _{2 2} a second pipe 6 b ₂ and easily shorten as necessary the downstream portion b _{2 June} when one has previously been led to shorten the worn downstream end of the flexible portion 6 _1b of the first pipe 6 _1, as described below.

The downstream end of the second pipe 6 ₂ comprises an anti-return valve 6 ₄ , for example of the type marketed by Swagelok under the reference SS-4-HC-1-4.

The valve 6 ₄ is located as close technically as possible to the upstream end of a first static mixer 7 disposed at the downstream end of the first pipe 6 ₁ . The valve 6 ₄ opens under the reactive pressure gasification browsing the pipe 6 ₂ When the pump 2 ₂ operates; and the valve 6 ₄ closes when the second pump 2-2 stops and the gasification reagent flow pressure decreases. As shown on the figure 4C , the valve 6 ₄ is connected to a connector 6 ₂ f at the downstream end of the inner pipe 6 ₂ by a second double union connection 6 ₄ a.

For the flexible portion 6 _1b of the first pipe 6 _1, a flexible thermoplastic may be used in outer diameter 42 mm and internal diameter of 32 mm, 30 to 100 m long. For the second pipe 6 ₂ , thermoplastic pipes of external diameter of 13.2 mm and internal diameter of 8.3 mm will be used.

The first mixer 7 consists of eight fins with helical surface 7a juxtaposed in the direction X ₁ X ₁ 'of the first mixer and the first pipe 6 ₁ , on a rod 7b. The rod 7b forms corrugations so that the entire surface of each helical fin is fixed on said rod in the longitudinal direction X ₁ X ₁ 'of the first pipe 6 ₁ and the first mixer 7 inserted inside the first pipe 6 ₁ . The rod 7b is thus corrugated so as to follow the contour or the = profile of the helical elements 7a. The rod 7b thus constitutes a reinforcement of this type of fixation.

The fins 7a are juxtaposed against each other in the longitudinal direction X ₁ X ₁ ', but the different portions of helical surfaces are not helically continuous, that is to say they are angularly offset so as to optimize the performance of said mixer in particular shifted at 90 ° successively relative to the axis X ₁ X ₁ '.

The addition of the rod 7b supporting the helical fins 7a is an original feature of the present invention because under the conditions implementation inside a small diameter pipe according to the present invention, the static mixer undergoes significant pressure. And it has been found that in the absence of support rod, a simple welding at the ends of the fins 7a to keep them connected together as in the prior art is insufficient.

Specifically, the helical elements have a diameter of substantially 30mm, a helical surface thickness of about 2mm, a length of about 50mm and an angular offset of about 90 °, the total length of the mixer being about 400mm.

The flow of gasification reagent leaving the valve 6 ₄ and the flow of matrix arriving at the valve 6 ₄ outside thereof, can mix intimately at the first mixer 7, by the helical shape of the fins whose diameter is just smaller than the inner diameter of the first pipe 6 ₁ .

Preferably, the different helical elements are successively reversed. The flow of material through the static mixer in the longitudinal direction X ₁ X ₁ ', becomes laminar and is divided into partial currents by a first helical element 7a, then redivated to the passage of a following helical element 7a and so on . The rotation of the product caused by the shape of the helical elements 7a accentuates the mixing phenomena. In principle, the helical elements 7a are not themselves in motion and in any case, no source of power is required other than that provided by said pumps to overcome the pressure drop induced by the baffles that form the successions of said helical elements 7a.

According to an original feature of the present invention, the downstream end of the first pipe 6 ₁ downstream of the first static mixer 7 is equipped with a stop 8 having a threaded outer surface 8a adapted to be screwed against the inner wall 6 ₁ e of the end swallows 6 ₁ f of the first pipe 6 ₁ . The explosive product fluid obtained by mixing of the matrix and the gasification reagent within the first static mixer 7 can flow through a central cylindrical orifice 8b of the abutment 8. As shown in FIG. Figure 5C , a key 8 ₁ having lugs 8 ₁ a cooperating with notches 8b1 at the periphery of the downstream end of the abutment 8 allows to screw and unscrew the stop 8 at will.

The central orifice 8b of the abutment piece 8 allows wide passage of the explosive product and avoids undesirable effects that may result from an increase in the nuisance pumping or blocking pressure related to the accumulation of explosive products at this level. . In practice, the inner diameter of the central opening of the abutment piece 8 is about 20 mm.

The stop 8 has the essential function of holding the static mixer 7 within the downstream end of the first pipe 6 ₁ . The unscrewing of the abutment 8 makes it possible to release the first mixer 7 from the downstream end of the first pipe 6 ₁ and thus to be able to cut the downstream end of the pipe 6 ₁ when it is damaged after a certain number of uses of the pipe. that the outer surface of the downstream end of the pipe 6 ₁ in contact with the walls of the drill holes 11 formed of rock mass 15 tend to damage the downstream end of the pipe 6 ₁ during the operation as described below .

It is also possible to remove the first mixer 7, if it is not desired to implement a method according to the invention varying the density of the explosive product produced continuously during a production cycle. In this case, the second pipe 6 ₂ is removed from the inside of the first pipe 6 ₁ by uncoupling at collar 1c as described above or by disconnecting pipe 1b and closing said second inlet 3 ₂ a by a plug and orienting the three-way valve V3 so that all the gasification reagent passes through the pipe 1b ₁ and mixes with the matrix flow upstream of the second mixer ₂₆ . At the outlet of the second mixer, the product explosive is transferred via the conduit 6 ₁ to a borehole in which the downstream end 6 ₁ f of the pipe 6 ₁ is disposed.

The static mixer 7 in practice extends over a length of 0.5 to 1 meter so that the explosive product produced is in reduced quantity inside the first hose 6 ₁ . Thus, it is possible to vary the composition and therefore the density of the explosive product 10, almost continuously and in real time at the outlet of the pipe 6 ₁ by adapting the relative proportions of flow and / or gasification reagent composition and matrix transferred into said first and second pipes, as described in the explosive production process described hereinafter.

Advantageously, a method according to the invention is used in which the density of the explosive product produced continuously is varied during the filling of a borehole 11 in a single pass, that is to say, without having to raise the pipe 6 during filling, as described below.

• huile minérale et/ou de vidange de moteur : 6,5 %,
• gasoil : environ 1%,
• agents tensioactifs non ioniques: 1%,
• nitrates d'ammonium et/ou de calcium et/ou sodium : environ 75%,
• eau : environ 15 à 20 %.

The emulsion consists of the following components:

• mineral oil and / or engine oil drain: 6.5%,
• diesel: about 1%,
• nonionic surfactants: 1%,
• ammonium and / or calcium and / or sodium nitrates: approximately 75%,
• water: about 15 to 20%.

To the above emulsion thus obtained, ammonium and / or calcium nitrates are added in a proportion of 15 to 35% and a catalyst for example of acetic acid in a proportion of 0.5 to 2%. to which one can also add aluminum (in the form of powder of particle size between about 100μm and 2mm) in a content of 1 to 10% by weight also. This matrix is thus obtained according to the present description within the first reservoir 1-1.

• huile minérale et/ou de vidange moteur : 4.55%,
• gasoil : 0.7%
• agents tensio-actif : 0.7%
• nitrate d'ammonium en solution : 52.5%
• eau : 11.55%
• nitrate d'ammonium solide en poudre : 30%

An example of a matrix formulation is therefore:

• mineral oil and / or engine oil: 4.55%,
• Gas oil: 0.7%
• surfactants: 0.7%
• ammonium nitrate solution: 52.5%
• water: 11.55%
• solid ammonium nitrate powder: 30%

To this matrix is added according to the process of the present invention, a gasification reagent which is here in particular an aqueous solution of about 20% of sodium nitrite and 80% of water may include catalysts such as sodium thiocyanate , sodium formate, zinc nitrate and / or calcium nitrate.

The method of sensitizing the matrix consists of a chemical reaction between said gasification reagent and the ammonium nitrate contained in said matrix. This chemical reaction releases a gas, in this case nitrite reacted with nitrate to form nitrogen gas, which generates sensitization of the product by the creation of "hot spots", that is to say interstices in the mixture product allowing the propagation of the shock wave, therefore the detonation of the explosive product. The product is therefore explosive because of this sensitization. The increase in the quantity of gas bubbles decreases the density of the product and therefore the explosive energy obtained for a constant volume of hole (volume energy).

The density of the basic emulsion (not supplemented) described above is for example about 1.4 to 1.6 and the density of the supplemented emulsion defining said matrix as described above, before mixing with the gasification reagent is 0.8 to 1.3.

The density of the mixture product before the gasification reaction in said first mixer is 1.25 to 1.45 according to the respective proportions of quantities and / or flow rates of said matrix and said gasification reagent and the density of the explosive product after gasification is 0.8 to 1.2.

The average energy of an explosive product of density 1.2 is 3.7 MJ / kg, ie 4.44 MJ / L. Thus, for an explosive product with a density of 0.5 to 1.5, the explosive energy will be 1.85 to 5.55 MJ / L.

• pour d = 0,8, Y = 0,0117X + 0,002, et
• pour d = 0,9, Y = 0,0085X + 0,0012, et
• pour d = 1, Y = 0,006X, et
• pour d = 1,1, Y = 0,0039X + 0,0019, et
• pour d = 1,2, Y = 0,0021X.

For a Y gasification reagent rate in L / min (product / liquid) as a function of a matrix flow X in kg / min of viscous product, the relation Y = aX + b is given by charts with values of a and b different according to the density values d of the explosive product obtained after gasification resulting from the reaction between said matrix and the gasification reagent by intimate mixing within the static mixer. Thus, the different values of a and b are for example here:

• for d = 0.8, Y = 0.0117X + 0.002, and
• for d = 0.9, Y = 0.0085X + 0.0012, and
• for d = 1, Y = 0.006X, and
• for d = 1.1, Y = 0.0039X + 0.0019, and
• for d = 1.2, Y = 0.0021X.

There is therefore a linear relationship between X and Y depending on the final density of the explosive product resulting from the reaction by intimate mixing of the two products.

The automated control and control unit 9 makes it possible to control the proportional valves V1 and V2 regulating the flows of matrix and gasification reagent, and the actuation and speed of the motors of the pumps 2-1 and 2-2. The flow rates X and Y are provided by calibrating the pump 2-2 speed sensor 2-2 for the values of X (kg / min) and by the flow meter 2-2a for the gasification reagent Y flow (L / 2). min).

In practice, since the gasification reagent R ₂ is in a smaller quantity and in liquid form, it is easier to control the flow rate so that it operates with a constant matrix flow rate X = 125 kg / min.

Thus, the operator driving the selected plant will select the desired explosive product densities as well as the corresponding quantities for each density based on his needs analysis in the relevant borehole given the surrounding rock mass environment. the hole to be felled. X being constant, the flow rate of gasification reagent is determined automatically from the chart according to the desired density. In practice, for each borehole 11, the operator will choose up to four different densities called d1, d2, d3 and d4. The densities d1 to d4 of explosive products to be produced and the corresponding quantities are entered at the level of the central unit 9 via a touch-sensitive keyboard 9a appearing on the screen of the graphic interface 9b. The operator can then start a pumping cycle.

• on charge 20 kg de produits explosifs de densité 1,2 à une valeur de 0,21 L/min avec par exemple un débit de réactif de gazéification de 0,21 L/min, et
• on change de consigne et on donne l'ordre de charger 25 kg de produit explosif 10 de densité 1 qui viendront donc se déposer pardessus les 20 kg de produits explosifs de densité 1,2 précédemment déposés au fond du trou depuis l'extrémité avale du tuyau 6₁, en mettant en oeuvre par exemple un débit de réactif de gazéification de 0,60 L/min ; puis

• on charge 50 kg de produits explosifs à densité de 0,9, pardessus le produit explosif précédemment déposé, en mettant en oeuvre par exemple un débit de réactif de gazéification de 0,80 L/min, puis
• on charge au sommet de la colonne, 30 kg de produit explosif 10 de densité d = 0,8, obtenu en transférant par exemple un débit de réactif de gazéification de 0,90 L/min.

The centralized and automated control unit 9 then automatically controls the regulation of the flow and therefore the flow rate of reagent R2 for a given matrix flow M. Thus, for example, the production cycle of a cylindrical hole 20 m deep and 115 mm in diameter will be performed as follows for a supplemented matrix having a density, in the example below, of about 1.3 :

• 20 kg of 1.2 density explosive products are loaded at a value of 0.21 L / min with, for example, a gasification reagent flow rate of 0.21 L / min, and
• the set point is changed and the order is given to load 25 kg of explosive product 10 of density 1 which will then be deposited on top of the 20 kg of explosive products of density 1.2 previously deposited at the bottom of the hole from the downstream end of the pipe 6 ₁ , in for example using a gasification reagent flow rate of 0.60 L / min; then

• 50 kg of explosive products with a density of 0.9 are charged, above the previously deposited explosive product, using for example a gasification reagent flow rate of 0.80 l / min, then
• at the top of the column, 30 kg of explosive product 10 of density d = 0.8, obtained by transferring, for example, a flow of gasification reagent of 0.90 L / min.

The automated central unit 9 thus makes it possible to control and control the gasification reagent flow rate values as described above, simply by adjusting the speed of the hydraulic motor of the second pump 2-2 transferring the gasification reagent, and by maintaining a substantially constant flow rate of 125 kg / min of said matrix. Such control and flow regulation of the gasification reagent makes it possible to vary, almost in real time, the product density value obtained at the outlet of the first static mixer 7 and discharged directly into the borehole, because of the automation of the control and regulation of the flow of gasification reagent by the central unit 9.

The CPU 9 may offer additional advantageous features such as the import and export of data, instructions and results in terms of quantity, throughput and density.

The method according to the invention is also advantageous in that it generates an improvement in terms of safety, the mixture product becoming explosive only at the end of the flexible hose 6 ₁ , thus avoiding the transport over a long distance of dangerous product within the pipe.

• la possibilité de faire varier en temps réel de façon optimale la densité du produit obtenu en mélange avec la matrice, mais aussi
• l'amélioration de la sécurité du procédé et enfin,
• une plus grand fiabilité mécanique de l'installation dans la mesure où aucun matériel n'est requis à l'extérieur du tuyau de dépose du produit explosif pouvant être en contact avec les autres composants nécessaires pour générer l'explosion que sont la charge d'amorçage 12, le détonateur 13 et surtout le fil de détonateur 14 qui est souvent source d'accident en cas de choc de produits métalliques à proximité.

The coaxial introduction system of the gasification reagent to bring it into contact with said matrix promotes an intimate mixture more faster and more efficient of the two components which induces, not only:

• the possibility to vary optimally in real time the density of the product obtained in mixture with the matrix, but also
• improving the safety of the process and finally,
• a greater mechanical reliability of the installation insofar as no material is required outside the pipe of deposit of the explosive product which can be in contact with the other components necessary to generate the explosion which is the load of priming 12, the detonator 13 and especially the detonator wire 14 which is often a source of accident in case of impact of metal products nearby.

With regard to the variation of the density of the product obtained almost in real time, it should be observed that the quantity of product contained within the downstream end of the pipe 6 ₁ is limited to the explosive product produced gasified in the second part downstream of the static mixer, or for a mixer 50 cm long in a pipe 6 ₁ 32 mm in internal diameter, an amount less than 0.5 kg of a relatively negligible value compared to the quantities of explosive products of different densities Therefore, it can be considered that the density variation is thus obtained almost in real time by modifying the gasification reagent and matrix rate ratios.

The measurement of the density can be carried out by weighing in the open air in a calibrated pot of known volume.

The process for producing a variable density explosive product according to the present invention therefore consists in varying the gasification of the explosive product in the blasthole, in a manner that is almost instantaneous in order to obtain a differentiation of the density of explosive product in the column. within the borehole, while performing only one loading pass.

Claims (14)

1. An installation for in situ production of explosive substance (10) by mixing a) a viscous substance, referred to as a "matrix", comprising a reverse emulsion of an aqueous phase of oxidizer and an oily phase of fuel, and b) a liquid substance containing a chemical compound suitable for reacting with said matrix to increase its explosive nature by gassing, referred to as a "gassing reagent", said installation comprising at least:

   - a first tank (1-1) containing said matrix based on said explosive emulsion; and

   - a second tank (1-2) containing said gassing reagent; and

   - a first circuit (1a) for transferring said matrix and comprising at least a first hose (6₁) that is flexible at least in part co-operating with a first pump (2-1) and a first valve (V1), being suitable for transferring said matrix separately to a first mixer, preferably a static first mixer (7); and

   - a second circuit (1b) for transferring said gassing reagent and comprising at least a second hose (6₂) that is flexible at least in part and co-operating with a second pump (2-2) and a second valve (V2), suitable for transferring said gassing reagent separately to said first mixer (7); and

   - said second hose (6₂) is arranged entirely inside the first hose (6₁) so as to form a set (6) of coaxial hoses, said first mixer being arranged inside the first hose at its downstream end (6₁f), said second hose terminating immediately upstream from said first mixer; and

   - the set (6) of coaxial hoses is connected to a winder drum (5) and is wound at least in part on said winder drum or is suitable for being wound thereon, the downstream end of the set (6) of coaxial hoses being arranged in or above a blast hole (11), preferably a substantially cylindrical borehole in which there are placed an explosive primer charge (12) and a detonator (13) that is connected to the surface by a detonator wire (14) ;

   the installation being characterized in that said first and second hoses are connected coaxially to each other at their upstream ends by a first connection part (3) comprising a sleeve with a cylindrical outer wall (3a) and an internal bend part (3b), said first connection part preferably being secured to a winder drum (5), said first connection part comprising:

   - a first inlet orifice (3₁a) forming an upstream opening of said sleeve and arranged axially in a longitudinal direction (XX') of the cylindrical wall of said sleeve, said first inlet orifice being connected to a portion, preferably a rigid portion, of said first circuit for transferring said matrix; and

   - a second inlet orifice (3₂a) arranged laterally at the cylindrical wall of said sleeve, forming an upstream opening of said bend part (3b) passing through the cylindrical wall of said sleeve and arranged perpendicularly to said longitudinal direction (XX'), said second inlet orifice being connected to a portion, preferably a rigid portion, of said second circuit for transferring said gassing reagent; and

   - a first outlet orifice (3₁b) forming a downstream opening of said sleeve and arranged axially on said longitudinal direction (XX') of the cylindrical wall of said sleeve, said first outlet orifice being connected by a first rotary coupling (4₁) to the upstream end of a rigid portion (6₁a) of said first hose upstream from a said winder drum; and

   - a second outlet orifice (3₂b) arranged axially on said longitudinal direction (XX') of the cylindrical wall of said sleeve, forming a downstream opening of said bend part (3b) inside said sleeve, said second outlet orifice being connected by a second rotary coupling (4₂) to the upstream end of said second hose for transferring said gassing reagent;

   - the upstream ends of said first and second hoses being fastened to said first and second outlet orifices of said first connection part (3) respectively via first and second rotary couplings (4₁, 4₂) allowing each to rotate separately about said longitudinal axis (XX') of said upstream ends of said respective first and second hoses, said first connection part (3) and said first and second rotary couplings (4₁, 4₂) being arranged upstream of a said winder drum so that said first and second outlet orifices (3₁b, 3₂b) are arranged on the axis of rotation (XX') of said drum.
2. An installation according to claim 1, characterized in that said second hose (6₂) includes a check valve (6₄) at its downstream end inside said first hose, the check valve (6₄) being suitable for opening and passing the stream of said gassing reagent under the pressure of said stream when the second pump is actuated, and being suitable for remaining closed and preventing leaks of gassing reagent when the second pump is not activated.
3. An installation according to claim 1 or claim 2, characterized in that:

   - said first hose comprises at least one rigid bend portion (6₁a) of the first hose assembled to a flexible portion (6₁b) of the first hose in leaktight and reversible manner by a clamp (6₁c), said bend rigid portion extending in part upstream from said drum and being secured thereto and being suitable for being driven in rotation about the axis of rotation of said drum when said drum is driven in rotation, said flexible portion of the first hose being suitable for being wound around said drum; and

   - said second hose comprises two flexible portions (6₂a, 6₂b) connected to each other by a rigid leaktight and reversible coupling of two-ended type (6₃), the flexible portion (6₂a) of said second hose arranged upstream from said coupling of two-ended type (6₃) being shorter than the flexible portion of said second hose arranged downstream (6₂b), said coupling of two-ended type (6₃) being arranged at said drum or upstream therefrom, preferably in the proximity of said clamp.
4. An installation according to any one of claims 1 to 3, characterized in that a hollow tubular abutment (8) having a longitudinal central opening (8b) is arranged removably at the downstream end of the first hose in order to retain said first mixer inside the first hose while allowing the explosive substance to pass through the central opening (8b) of said abutment, a thread (8a) on a cylindrical outside wall enabling said abutment to be screwed in the inside wall (6₁e) of said first hose, and thus be fastened releasably thereto, preferably by using a key (8₁) suitable for co-operating with the downstream end of said longitudinal central opening in order to screw said abutment into said first hose or to unscrew it therefrom in order to extract it from said first hose.
5. An installation according to any one of claims 1 to 4, characterized in that said first mixer (7) is a static mixer having a plurality of fins (7a), each presenting a helical surface, the fins preferably extending in their axial direction over a length corresponding to one pitch of the corresponding helical curve, said helical surfaces being supported by a common reinforcing rod (7b) to which they are fastened in juxtaposed manner in the longitudinal direction of said first hose, said successive helical surfaces being offset angularly in rotation about the common virtual axis of their helical surfaces, which coincides substantially with a longitudinal axis of said first hose of axis coaxial with said first hose, the diameter of said helical surfaces being substantially identical to or just sufficiently less than the inside diameter of the first hose to allow said fins to turn under the effect of the pressure of the streams of mixed matrix and reagent passing through them.
6. An installation according to any one of claims 1 to 5, characterized in that an automatic central monitoring and control unit (9) having electronic means controlled by software with a keyboard and/or a graphics interface serves to monitor and control the respective quantities and flow rates of said matrix and/or preferably of said gassing reagent, and to vary the specific gravity of the resulting explosive substance by monitoring and controlling the first and/or second valves and/or controlling the speeds of said first and/or second pumps, said central unit preferably being carried on a motor-driven vehicle (10), more preferably said vehicle carrying said first and second tanks and said first and second pumps.
7. A method of in situ production of an explosive substance (10) using an installation according to any one of claims 1 to 6, the method comprising the steps of:

   1) transferring a viscous substance of said matrix and a liquid substance of said gassing reagent respectively in said first and second coaxial hoses; and

   2) mixing said matrix and said gassing reagent in a said first mixer; and

   3) depositing said explosive substance at the outlet from said first mixer in a blast hole (11), preferably a substantially cylindrical borehole in which an explosive primer charge (12) and a detonator (13) connected to a detonator wire (14) going to the surface have previously been placed.
8. A method according to claim 7, characterized in that the quantities and/or flow rates of said matrix and of said gassing reagent are monitored and controlled in such a manner as to produce a said explosive substance of specific gravity having a determined value at the outlet from the first mixer.
9. A method according to claim 8, characterized in that the specific gravity of the resulting explosive substance is caused to vary during filling depending on the quantity of explosive substance that has already been deposited and/or depending on the depth at which the explosive substance is deposited in a given hole or from one hole to another in different holes.
10. A method according to claim 9, characterized in that determined quantities of explosive substances having respective different determined specific gravity values are selected and controlled automatically for depositing successively in a hole being filled, preferably continuously.
11. A method according to claim 9 or claim 10, characterized in that in step 1), said matrix and said gassing reagent are transferred separately respectively from said first and second tanks respectively into the first and second hoses co-operating respectively with a first pump (2-1) and a first valve (V1) or with a second pump (2-2) and a second valve (V2), and said matrix is monitored and controlled to have a constant flow rate by controlling the speed of the first pump (2-1) and/or the opening of said first valve (V1), while the flow rate of said gassing reagent is caused to vary by controlling the speed of the second pump (2-2) and/or the opening of said second valve (V2).
12. A method according to claim 11, characterized in that a constant flow rate for said matrix is monitored and controlled by controlling the speed of the first pump (2-1) with the help of a speed sensor (2-1a) sensing the speed of said first pump, and the flow rate of said gassing reagent is caused to vary by controlling the speed of the second pump (2-2) with the help of a flowmeter (2-2a).
13. A method according to any one of claims 7 to 12, characterized in that use is made of:

    - a said matrix of specific gravity in the range 1 to 1.7 of a reverse or "water-in-oil" base emulsion obtained by mixing a) an organic continuous phase constituted by a mixture of mineral oils and of gas oil, and b) of a discontinuous aqueous phase of various oxidizer salts in aqueous solution based on ammonium and/or sodium and/or calcium nitrate(s) at a flow rate in the range 25 kg/min to 300 kg/min; and

    - a "gassing reagent" solution of specific gravity in the range 0.5 to 1.5 based on sodium nitrite and/or thiocyanate, at a flow rate in the range 0.1 L/min to 2 L/min; and

    - with the ratio of the reagent flow rate divided by the matrix flow rate lying in the range 0.1 to 2 liters per hundred kilograms of the proportion.
14. A method according to any one of claims 7 to 13, characterized in that the following steps are performed when the downstream end of the first hose is worn and/or damaged:

    a) withdrawing said first mixer from said first hose;

    b) cutting off the downstream end of the worn and/or damaged first hose;

    c) replacing said first mixer inside said first hose;

    d) disassembling the upstream end of the flexible portion of said first hose and extracting an upstream portion of said second hose and disassembling an upstream first portion (6₂a) from the flexible downstream second portion (6₂b) of the second hose; and

    e) extracting said flexible downstream second portion (6₂b) of the second hose from the first hose and shortening it, then replacing it in the first hose and connecting it once more to the upstream portion of the second hose that has remained inside a rigid upstream portion of the first hose.

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