GB1596685A

GB1596685A - Mixing pulverulent drying substances and/or fluent media with one or more liquids

Info

Publication number: GB1596685A
Application number: GB1941/78A
Authority: GB
Original assignee: SUPRATON ZUCKER
Current assignee: SUPRATON ZUCKER
Priority date: 1977-01-19
Filing date: 1978-01-18
Publication date: 1981-08-26
Also published as: FR2377837A1; AT366931B; ATA778A; IT1092111B; JPS53104465A; NL7800129A; IT7819383A0; JPS6214328B2; ES466108A1

Description

(54) MIXING PULVERULENT DRYING SUBSTANCES AND/OR FLUENT MEDIA WITH ONE OR MORE LIQUIDS (71) We SUPRATON F. J. ZUCKER K.G., a Kommanditgesellschaft organised and existing under the Laws of the German Federal Republic, of Am Henselsgraben 5, 4040 Neuss 21, German Federal Republic.

do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed. to be particularly described in and by the following statement: The invention relates to a method and apparatus for mixing pulverulent drying substances and/or fluent media with one or more liquids, especially to produce a suspension or dispersion.

The mixing of drying constituents in a wet constituent to produce homogeneous suspension or dispersion not infrequently makes for further difficulties, especially in the attaining of a homogeneous mixing in a continuous process. In such a process it is an essential requirement that the ratio in parts by weight of solid and liquid can be kept constant. In a batch process, for example with use of an agitator in a receptacle. a satisfactory dispersion can be obtained if the agitation is carried on for a sufficient length of time. Such a measure is wasteful in energy and time and moreover cannot be carried out at all times. Bulky mixing apparatuses are necessary for an efficient mixing process. Moreover. the receptacles required are large and for this reason the required amount of space is very considerable.There are also difficulties in the mixing of solids in liquids when a solid can be wetted with the liquid only with difficulty.

especially when the quantity of the liquid constituent is to be kept small.

The object of the invention is to carry out the production of mixtures or suspensions of pulverulent drying substances and/or fluent media with one or more fluid media, in which the process for obtaining a homogeneous more or less pasty composition can be carried out continuously in such a way that a constant ratio of the parts by weight of solid and liquid is guaranteed.

According to one aspect of the invention there is provided a method of mixing pulverulent drying substances and/or fluent media with one or more liquids, especially to produce a suspension or dispersion, wherein a flow of one or more pulverulent drying substances and/or fluent media is subjected to the action of at least one liquid constituent, maintained at a pressure of 10 bar to 1000 bar, supplied through high-pressure jets in multiple arrangement with generation of turbulence, the mixture thus obtained is discharged continuously, and the supply of drying substance and/or fluent medium and high-pressure liquid constituent is effected in a predetermined ratio in accordance with weight and volume.

Through the use of at least one liquid jet under high pressure there is achieved a mixture of the constituents concerned in a purely hydraulic way such that while preserving the predetermined dosage rate of the quantities to be brought together there is obtained a mixture of the constituents or a suspension or dispersion in which the parts by weight of the constituents remain as predetermined in the more or less pasty composition. There is brought about through the use of a hydraulic high pressure of a liquid constituent a loss of head through which a complete penetration of the drying constituents with the liquid constituent or constituents is guaranteed. This also applies in the bringing together of large quantities of pulverulent substances with relatively little liquid in order to obtain a homogeneous pasty composition.A subsequent separation of the constituents does not take place, rather the mixture or suspension and the like obtained remains stable for a long time in so far as the homogeneity is concerned. The completion of the mixing takes place in as short a time as possible.

The mixture or suspension or dispersion can thereafter be used immediately. Expenditure in construction is extremely small. The mixing can more especially be carried out in a continuous operation.

The mixing by means of at least one liquid component under high pressure may be carried out both for one or more pulverulent drying substances and also for fluent media as well as for drying substances and fluent media at the same time. In the latter case the drying constituent and one or more liquid constituents can be mixed with one another beforehand. Furthermore several liquid constituents can first of all be mixed with one another and the mixture then subjected to the action of at least one jet of liquid under high pressure. It is moreover possible to subject all drying constituents and liquid constituents intended for mixing, at the same time to the action of the liquid constituent under high pressure. without previous mixing.It is furthermore possible to still further drying constituents and/or liquid constituents at the same time with a liquid constituent under high pressure.

The constituents of the pulverulent drying substances and the liquids to be mixed with the drying constituents may be brought together in amounts set in advance according to weight or volume. Preferably the high-pressure liquid jet or jets are supplied with generation of turbulence in the flow of the drying substance and/or fluent medium.

Depending on the kind of pulverulent drying components and/or fluent media, which for example may consist of water or a solution, the pressure of the liquid jet is adjusted and this pressure can be kept within wide limits from 10 to 1000 bar.

Preferably pressures of 50 to 250 bars are maintained.

In accordance with another aspect of the invention there is provided an apparatus for mixing pulverulent drying substances and/or fluent media with one or more liquids.

especially to produce a suspension or dispersion, the apparatus comprising a tubular mixing chamber. means for conveying one or more pulverulent drying substances and/ or fluent media to the mixing chamber at a predetermined rate, inlets into the tubular mixing chamber in the form of nozzles in multiple arrangement. the nozzles being so adjustable that the pressures of jets of liquid mixing therefrom into the tubular mixing chamber can be kept to 10 bar to 1000 bar.

and means for supplying pressurised liquid to the nozzles, whereby a mixture of drying substance and/or fluent medium and pressu rised liquid can be discharged continuously from the tubular mixing chamber in a predetermined ratio in accordance with weight and volume.

These inlets may be circular section or flat section discharge nozzles. They may be directed axially, radially, and/or diagonally of the longitudinal axis of the tubular mixing chamber. In this way intended turbulences are introduced for pressure mixing into the composition subject to the mixing process.

Considered in cross section a tangential arrangement of the inlets of the tubular mixing chamber particularly assists the desired turbulence effect. Especially when using abrasive media, the process and the apparatus in accordance with the invention are especially advantageous, as in the equipment in which the mixing process takes place, there are no moving mechanical parts and there is no need for such.

The mixing process and the mixing apparatus in accordance with the invention are also suitable for all pulverulent substances which can be wetted with a greater or lesser degree of difficulty and which are to be mixed with a liquid, solution or the like.

This applies also to substances which can swell and can gush up and which generally swell on addition of a liquid and/or receive viscous qualities to a greater or lesser extent.

A particular application is the production of a cement with the water, thus the direct production of the cement bond. It is known that cement bond is a water-cement mixture which on the production of concrete components absorbs the admixed other substances - usually sand and gravel - also termed so-called aggregate.

The quality of a concrete component is dependant in the first instance on the quality of the cement bond. The latter in accordance with the present state of the art, is determined by the qualitv of the cement.

For this reason there are different kinds of cement which produce different criteria both with regard to strength to be anticipated and also with regard to applicability such, for example. as setting time, flovabil- ity, behaviour under water.

Naturally the strength of a concrete component. in so far as it is influenced by the quality of the cement bond is also influenced bv the concentration of the cement bond (the water-cement ratio).

Based on the fact that with cement there is an extremely fine product with regard to particle size, thus a product with a high specific surface. this high specific surface having to be wetted with a small as possible amount of water and indeed uniformlv. in order that penetration of water mt(i the surface of the cement core can take place.

the water-cement dissemination is of decisive importance with regard to the quality of the cement glue.

In the mixing process according to the present state of the art no cement blind is generally separately produced, but is formed on the simultaneous admixture of additives, cement and water. This mixing procedure can be simply designated as coarse, both in small batches, for example prepared manually in piles and in large batches in tumbler mixers or agitator mixers in which the agitators often undergo planetory movements, with regard to the aforementioned micro dimensions of the cement surfaces and the desired degree of dispersion.

If on the other hand in accordance with the invention cement, for example of the quality 350 to DIN 1164, is brought together with an accelarated pressure jet of water and thereafter the cement - water mixture or the cement - water mixture at this moment in the stage of formation in a deviating or deflecting zone, there is brought about a surprising effect that the water absorbing capacity of the cement has considerably increased relative to a cement bond produced by stirring up cement and water.

Cement and water, the latter having a high speed and thereby also accelerating the cement, leave the tube at high speed and are subjected according to the invention to a deflecting and shearing action of such a nature that they are projected against a plate mounted in front of the tube disposed at approximately or exactly right angles to same.

With suitable arrangement of the jet it is however also possible to achieve the desired deflecting and shearing effect in the tube itself. thus without there being present an additional deflecting plate after the outlet from the tube.

Through the hereinbefore bringing together of cement with water with high accelaration or under high pressure there is a spontaneous homogeneous blending of the two substances, which obviously leads to an optimum dispersion on the surface of the cement of the water in the quantities available. It furthermore appears to be the case that penetration of the water into the boundary layers of the cement granule is hastened by this procedure and thus prevents precipitation.

The invention thus makes it possible to produce cement of high strength with advantageous setting behaviour in a simple and reliable manner. It is not necessary to mix the whole of the additives at the same time with the water but is is even advantageous - not least in so far as the apparatus is concerned - if the mixture of the cement bond takes place in a first stage and this cement bond produced in such manner is mixed with the additive or. in the event that several are present, with the additives in a second stage following directly thereupon.

There is however also the possibility of introducing part of the additives with the cement in the previously described tube and undertaking a treatment similar to the latter.

Another application, for example for suspensions strongly subject to swelling, is the use of bentonite (active clay) in suspensions, for example for fusing and hardening of louvred slides in the building industry.

The bentonite suspensions are also used for making smooth and, reinforcing bore holes of all kinds in the ground. Chalk and also pharmaceutical powder may be mentioned as further examples. In the food stuffs industry thickeners such as carrageenan play an important role, for example in the production of ice-cream or also in the cosmetic industry, for example in the production of tooth paste. All such substances may be transformed into stable mix suspensions and dispersions in a continuous process by means of the method and the apparatus according to the invention.

Embodiments of the invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figures 1 and 2 show a first apparatus for mixing pulverulent substances and/or fluent media with a liquid according to the invention in elevation and in plan, diagramatically.

Figure 3 is a section through the apparatus of Figure 1 along the line III-III.

Figures 4 and 5 represent in section and in plan a second mixing apparatus of the invention schematically, the tubular mixing chamber being angular in this embodiment; and Figure 6 shows a modified form of the mixing apparatus of Figures 4 and 5, chiefly for the production of cement glue.

The apparatus 1 of Figures 1 and 3 for mixing pulverulent substances and/or fluent media with a liquid with addition of predetermined quantities provides for a bringing together of several solid constituents. To this end there may be provided for example three supply bins 2. 3 and 4. which are provided with funnel-shape bottom portions. At the lower end of the funnel 5, 6, 7 there are valved compartments 8, 9 and 10 from which extend conveying tubes 11, 12 and 13 or conveyor chutes, conveyor belts to a common mixing tube 14.The removal of the pulverulent solid constituents and/or fluent media from the supply bins takes place in portions in appropriate measured amounts, which can be effected, for example through the feeding screws 15, 16 and 17 rotating at predetermined speed, so that the ratio of the measured amounts of the drying constituents and/or fluent media can be maintained with certainty. An intermediate feeding screw 18 may be provided for the conveyor tubes 11 and 13.

There is joined to the common tube 14 into which the three constituents are introduced in measured amounts a mixing and discharge chamber 19 into which lead inlets 20, 21 and 22 for introducing a liquid or water which is under high pressure. Said inlets may be one or more circular section and/or flat section discharge nozzles which open into the mixing chamber 19 axially and/or radially. It is preferable that the part of the mixing chamber 19 in which the discharge nozzles are mounted be surrounded by a casing tube 23 to which a tube 24 leads from a high-pressure directconnected motor-driven pump 25. The tubular mixing chamber is inclined in this embodiment, that is it is arranged at an angle to the vertical.

A pre-dosing in accordance with weight or volume of the constituents to be mixed, which are continuously brought together at the common tube 14, are thereafter subjected simultaneously to the action of high pressure liquid jets by means of the nozzles 20, 21, 22, whereby the mixing process is carried out fully hydraulically without the assistance of mechanical parts. The liquid jets which are under high pressure subject the constituents to such a shearing gradient that. especially by means of the turbulences brought about, the finished mixture suspension or dispersion is available in the mixing chamber 19.

The mixing process takes place continuously. The impact effect of the high pressure liquid jet converts the supply constituents to the mixture which is desired and in the case of drying constituents into the desired more or less pasty composition or the suspension or dispersion. In this way a complete homogeneity of the end product is guaranteed and the end product is stable with regard to its properties with reference to the ratio of parts by weight of solid andlor liquid on the one hand and liquid on the other hand at least up to the further treatment. generally for a longer time. The mixture obtained can be applied directly to the further treatment.

One or more drying components and/or liquid components can be added to the mixture obtained either simultaneously with the high pressure liquid jet or even within the mixing zone.

The homogeneous end product may be introduced into vessels or receptacles. for example tank trucks serving for the remov al, whereby there is no danger of separation of the constituents taking place through a more or less long conveying path. The apparatus is preferably so designed that the tubular mixing chamber 19 is swingably mounted about the short feed pipes 14 so that in the continuous operation a series of conveyor receptacles and the like can be filled one after another whereby there need be no interruption in the continuous process.

The mixing apparatus 28 of Figures 4 and 5 has a vertically extending mixing chamber 29, which is provided with a right angled or approximately right angled angular chamber portion 30 which may be tubular. There is set upright on the tubular mixing chamber 29 a funnel 31 to which the solid constituents are supplied in pre-measured quantities through pipelines 32 and 33. The mixing chamber 29 is provided with nozzles 34 and 35 directed at an acute angle to the axis of the chamber and through these nozzles liquid or liquids under high pressure are introduced into the mixing chamber 29, the supply pipelines 36 and 37 serving for this purpose. High pressure pumps are denoted 38 and 39. A branch pipeline 36a leads from the supply pipeline 36 to the funnel 31 and opens tangentially to the funnel.The pressure of the liquid can be regulated by means of the valve 40 in the branch pipeline 36a.

The supply pipelines 32 and 33 for the pulverulent solid constituents are so arranged in relation to the funnel 31 that the outlets 32a and 33a are disposed at the side of the funnel, so that the solid constituents come together directly with a liquid vortex 41 supplied through the branch pipeline 36a.

Thereafter the drying components prewetted with liquid are subjected in the vertical mixing chamber to the high pressure liquid jets from the nozzles 34 and 35 with a high shearing gradient producing turbulences. This mixture then strikes on the lower part 30a of the angular chamber portion 30 with high acceleration and impetus, whereby further considerable turbulences 42 are produced through the deflection of the solid - liquid mixture and the re-bound effect. Thereafter the prepared mixture passes through the outlet 43 for further utilization. The described arrangement is particularly suitable for example for the production of a finely-divided cement glue.

In Figure 6 there is shown further apparatus 45. preferably for the production of a cement bond according to the invention.

Water at a pressure of about 45 bar is brought from a storage vessel 46 through a for example high pressure piston pump 47 which is driven bv an electric motor 48 by way of couplings 49. This water is supplied through a pipeline 50 to a pluralitv of nozzles one of which is shown at 51. The manometer 52 is built in the pipeline for control of the pressure upstream of the nozzle. Each nozzle 51 is so arranged that it forms an angle of for example 23 with the upright tubular mixing chamber 53. The mixing chamber has at one end a funnel shaped attachment 54 into which the cement is supplied through a proportioning screw 55. Within the funnel 54 a liquid vortex can be created in the same way as in Figure 4.

Through the stepless gear 56 with a motor 57 the amount of cement and subject thereto the water - cement ratio can be varied.

Below the nozzle 51 is a plate 58 the surface of which is preferably provided with a wear-resistant material such for example as nickel - silicon - steel - iron alloy. The cement and water mixture re-bounds at high speed on the plate 58 and flows partly through rebound energy and partly because of its own weight into the funnel 59 arranged below the plate and from there through the outlet pipeline 60 into the interior of mixing drum 61. The latter is disposed substantially horizontally on the roller support 62 and is rotated from the electric motor 63. Through a conveyor belt 64 a pre-measured amount of aggregate also gets into the interior of the drum 61. Through the rotation of the drum the cement glue already prepared at this stage is mixed with the aggregates and uniformly distributed on the surface of the latter.The mixture is delivered to the drum outlet by delivery members 65 arranged internally of the drum and forming an angle relative to the longitudinal axis of the latter.

Such an arrangment enables a high productive capacity to be achieved and a qualitative high grade of concrete to be produced with a relatively small technical expenditure.

With use of the appartus described the following surprising result has been ascer tainted, numerically expressed, in comparison to a customary agitating apparatus; The mixture of 1000g cement and 60()g water was stirred intensively with a three bladed tubular stirrer for five minutes at a speed of rotation of 1140 in a vessel of 2000cam' capacity and a diameter of 100 mm.

A part of this mixture was then transferred into a vertical cylinder:the vertical cylinder had a scale division. Through the latter a deposit of the cement portion in the mixture of 2(1.2 % could be ascertained after one hour.

In comparison with this test the same cement was mixed with the same amount of water in accordance with the invention in the manner that water in a tube at an angle of 200 and at a pressure of 40 bar is introduced through a nozzle of 1 mm dia-meter. The tube itself had in this test an internal diameter of 74 mm and a length of 480 mm. The tube was arranged vertically so that the acute angle which is formed by the axis of the nozzle on the one hand and the axis of the tube on the other hand points approximately in the direction of the centre of the earth. It is thereby possible to be able to introduce free-falling cement into the side of the tube which forms an acute angle with the nozzle. This precedure is supported by the fact that required by the speed of the water there is a sub-pressure at the upper end of the tube.After transfer of the mixture into a vertical cylinder there was after one hour a deposit of the cement portion in the mixture of only about 10%.

It is manifest that the hereinbefore described technique represents only one of the possible forms of the method according to the invention. This method may have application with results just as good in the form that it can be introduced into the present mixing plants which usually operate with planetary mixers, in the manner that the mixture according to the invention and prepared cement glue are added to the aggregate in the planetary mixer and are mixed with the latter.

WHAT WE CLAIM IS: 1. A method of mixing pulverulent drying substances and/or fluent media with one or more liquids, especially to produce a suspension or dispersion, wherein a flow of one or more pulverulent drying substances and/or fluent media is subjected to the action of at least one liquid constituent, maintained at a pressure of 10 bar to 1000 bar, supplied through high-pressure jets in multiple arrangement with generation of turbulence, the mixture thus obtained is discharged continuously, and the supply of drying substance and/or fluent medium and high-pressure liquid constituent is effected in a predetermined ratio in accordance with weight and volume.

2. A method according to claim 1, wherein the pressure is between 50 bar and 250 bar.

3. An apparatus for mixing pulverulent drying substances and/or fluent media with one or more liquids, especially to produce a suspension or dispersion, the apparatus comprising a tubular mixing chamber, means for conveying one or more pulverulent drying substances and/or fluent media to the mixing chamber at a predetermined rate, inlets into the tubular mixing chamber in the form of nozzles in multiple arrangement, the nozzles being so adjustable that the pressure of jets of liquid issuing therefrom into the tubular mixing chamber can be kept to 10 bar to 1000 bar, and means for supplying pressurised liquid to the nozzles, whereby a mixture of drying substance and/or fluent medium and pressurised liquid can be discharged continuously from the tubular mixing chamber in a predetermined ratio in accordance with weight and volume.

4. An apparatus according to claim 3, wherein the nozzles are distributed not only over the periphery of the tubular mixing chamber, but also an upstream end-wall of said chamber, and the region of said cham

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. shaped attachment 54 into which the cement is supplied through a proportioning screw 55. Within the funnel 54 a liquid vortex can be created in the same way as in Figure 4. Through the stepless gear 56 with a motor 57 the amount of cement and subject thereto the water - cement ratio can be varied. Below the nozzle 51 is a plate 58 the surface of which is preferably provided with a wear-resistant material such for example as nickel - silicon - steel - iron alloy. The cement and water mixture re-bounds at high speed on the plate 58 and flows partly through rebound energy and partly because of its own weight into the funnel 59 arranged below the plate and from there through the outlet pipeline 60 into the interior of mixing drum 61. The latter is disposed substantially horizontally on the roller support 62 and is rotated from the electric motor 63. Through a conveyor belt 64 a pre-measured amount of aggregate also gets into the interior of the drum 61. Through the rotation of the drum the cement glue already prepared at this stage is mixed with the aggregates and uniformly distributed on the surface of the latter.The mixture is delivered to the drum outlet by delivery members 65 arranged internally of the drum and forming an angle relative to the longitudinal axis of the latter. Such an arrangment enables a high productive capacity to be achieved and a qualitative high grade of concrete to be produced with a relatively small technical expenditure. With use of the appartus described the following surprising result has been ascer tainted, numerically expressed, in comparison to a customary agitating apparatus; The mixture of 1000g cement and 60()g water was stirred intensively with a three bladed tubular stirrer for five minutes at a speed of rotation of 1140 in a vessel of 2000cam' capacity and a diameter of 100 mm. A part of this mixture was then transferred into a vertical cylinder:the vertical cylinder had a scale division. Through the latter a deposit of the cement portion in the mixture of 2(1.2 % could be ascertained after one hour. In comparison with this test the same cement was mixed with the same amount of water in accordance with the invention in the manner that water in a tube at an angle of 200 and at a pressure of 40 bar is introduced through a nozzle of 1 mm dia-meter. The tube itself had in this test an internal diameter of 74 mm and a length of 480 mm. The tube was arranged vertically so that the acute angle which is formed by the axis of the nozzle on the one hand and the axis of the tube on the other hand points approximately in the direction of the centre of the earth. It is thereby possible to be able to introduce free-falling cement into the side of the tube which forms an acute angle with the nozzle. This precedure is supported by the fact that required by the speed of the water there is a sub-pressure at the upper end of the tube.After transfer of the mixture into a vertical cylinder there was after one hour a deposit of the cement portion in the mixture of only about 10%. It is manifest that the hereinbefore described technique represents only one of the possible forms of the method according to the invention. This method may have application with results just as good in the form that it can be introduced into the present mixing plants which usually operate with planetary mixers, in the manner that the mixture according to the invention and prepared cement glue are added to the aggregate in the planetary mixer and are mixed with the latter. WHAT WE CLAIM IS:

1. A method of mixing pulverulent drying substances and/or fluent media with one or more liquids, especially to produce a suspension or dispersion, wherein a flow of one or more pulverulent drying substances and/or fluent media is subjected to the action of at least one liquid constituent, maintained at a pressure of 10 bar to 1000 bar, supplied through high-pressure jets in multiple arrangement with generation of turbulence, the mixture thus obtained is discharged continuously, and the supply of drying substance and/or fluent medium and high-pressure liquid constituent is effected in a predetermined ratio in accordance with weight and volume.

ber wherein the nozzles are mounted is enclosed by a common casing tube to which a tube leads from the means for supplying pressurised liquid.

5. An apparatus according to claim 4, wherein the tubular mixing chamber is pivotable about a vertical axis.

6. An apparatus according to claim 3, wherein the tubular mixing chamber extends vertically, beneath the nozzles the chamber has an angled portion, at the top of the chamber there is a funnel for receiving the drying substance and/or fluent medium, and there is a connection from the means for supplying pressurised liquid to the funnel so arranged as to produce a liquid vortex in the funnel.

7. An apparatus according to claim 6, wherein the angled portion is disposed at an angle of approximately 90" to the tubular mixing chamber, the floor of the angled portion serving as an impact or rebound surface.

8. A method of mixing pulverulent drying substances and/or fluent media with one or more liquids, substantially as hereinbefore described with reference to the accompanying drawings.

9. Apparatus for mixing pulverulent drying substances and/or fluent media with one or more liquids, substantially as hereinbefore described with reference to Figures 1 to 3, of the accompanying drawings.

10. Apparatus for mixing pulverulent drying substances and/or fluent media with one or more liquids, substantially as hereinbefore described with reference to Figures 4 and 5 of the accompanying drawings.

11. Apparatus for mixing pulverulent drying substances and/or fluent media with one or more liquids, substantially as hereinbefore described with reference to Figure 6 of the accompanying drawings.