Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
  • B22D1/00—Treatment of fused masses in the ladle or the supply runners before casting
  • B22D1/002—Treatment with gases
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
  • C22B21/00—Obtaining aluminium
  • C22B21/06—Obtaining aluminium refining
  • C22B21/064—Obtaining aluminium refining using inert or reactive gases
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
  • C22B21/00—Obtaining aluminium
  • C22B21/06—Obtaining aluminium refining
  • C22B21/066—Treatment of circulating aluminium, e.g. by filtration
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
  • C22B9/00—General processes of refining or remelting of metals; Apparatus for electroslag or arc remelting of metals
  • C22B9/05—Refining by treating with gases, e.g. gas flushing also refining by means of a material generating gas in situ
  • C22B9/055—Refining by treating with gases, e.g. gas flushing also refining by means of a material generating gas in situ while the metal is circulating, e.g. combined with filtration

Definitions

• the invention relates to a device for treating a flow of liquid metal, in particular aluminum, an aluminum alloy, magnesium or a magnesium alloy.
• liquid metal It is known to treat a stream or a batch of liquid metal before pouring it in the form of a metallurgical product, such as a shaped part, a billet or a plate.
• the treatment of liquid metal generally aims to rid it of dissolved gases (especially hydrogen), dissolved impurities (especially alkali metals) and solid or liquid inclusions which could adversely affect the quality of the cast products.
• This treatment typically comprises an operation of treatment by blowing a gas into the liquid metal, which operation is carried out in a first bag.
• the process gas may be inert and insoluble in the liquid metal (such as argon) or reactive (such as chlorine), or a mixture of these.
• the inert and insoluble gas absorbs the dissolved gas by dilution effect and carries it with it.
• the reactive gas reacts with certain dissolved impurities and thus generates liquid or solid inclusions which, like those already present in the liquid metal, can be eliminated by a filtration operation in a second bag fitted with a filter, such as a bag. deep bed filtration, called “deep bed filter” in English.
• the Applicant has sought a compact liquid metal treatment device which provides an industrial and economical solution to the drawbacks of the devices of the prior art.
• the invention relates to a device for treating a flow of liquid metal comprising a treatment bag comprising fixed injection means and located in the upstream part of the treatment bag and at least one filtration means in its part. downstream.
• the Applicant has had the idea of combining the means for injecting the treatment gases and the filtration means inside a compact treatment compartment. This consolidation considerably reduces the complexity of the liquid metal treatment system and facilitates their maintenance.
• the Applicant has, moreover, had the idea that the grouping of these processing means in the same compartment could lead to an improvement in the processing by the fact that, on the one hand, the mixing of the liquid metal caused by insufflation of gas in it prevents the accumulation of solid matter near the filtration means (and in particular on the surface of the filtration slab (s) when these filtration means are used) and that, on the other hand, the filtration means promotes the formation of re-circulation flows of the liquid metal inside the compartment which tend to increase the residence time and the efficiency of the treatment.
• the invention also relates to the use of said device for the treatment of a flow of liquid metal.
• Said liquid metal is typically chosen from the group consisting of aluminum, aluminum alloys, magnesium or a magnesium alloy.
• FIGS. 1 to 8 give a schematic representation of it and illustrate advantageous embodiments, and the detailed description which follows.
• FIG. 1 illustrates, in longitudinal section and seen from the side, an embodiment of the invention in which the device comprises a single filtration slab.
• FIG. 2 illustrates, in longitudinal section and seen from the side, an embodiment of the invention in which the device comprises a baffle and two filtration slabs.
• FIG. 3 illustrates, in longitudinal section and seen from the side, an embodiment of the invention in which the device comprises a single filtration slab.
• FIG. 4 illustrates, in longitudinal section and seen from the side, an embodiment of the invention in which the device comprises a single filtration slab.
• FIG. 5 illustrates, seen from above, an embodiment of the invention in which the means are arranged in line.
• FIG. 6 illustrates, in cross section, an embodiment of the invention in which the injection means are arranged at the bottom of the treatment compartment.
• FIG. 7 illustrates, seen from above, an embodiment of the invention in which the injection means are arranged in line and alternately on either side of the treatment compartment.
• FIG. 8 represents parameters for dimensioning the device of the invention.
• He and Hs correspond respectively to the normal heights of the metal liquid in the feed (15) and discharge (16) spouts.
• Ne and Ns correspond respectively to the height of the bottom (37, 38) of the feed (15) and discharge (16) spouts relative to the bottom (28) of the treatment compartment (20).
• H corresponds to the normal average height of the liquid metal in the treatment compartment (20).
• Ho corresponds to the average interior height of the treatment compartment (20).
• the device (1) for treating a flow of liquid metal comprises a treatment bag (2) comprising a treatment compartment (20), inlet means (7, 9) and outlet (8, 10) of the liquid metal, connection means (11, 12, 13, 14) to at least one supply chute (15) in liquid metal and to at least one discharge chute (16 ) liquid metal, and means for injecting (22, 22a, 22b) of a treatment gas into the liquid metal arranged in at least one side wall (32, 33) of the pocket (2), said means d liquid metal inlet and outlet each comprising at least one orifice (9, 10) which is positioned so as to be entirely below the level (26) of the liquid metal during processing, in order to prevent the introduction of ambient air in the compartment being treated, and is characterized in that said treatment compartment (20) comprises an upstream part (23) and a downstream part (24), in that said injection means (22, 22a, 22b) are located in said upstream part (23) and in that said compartment (20) further comprises at least one first filtration means (40) located
• the main longitudinal axis (6) of the device of the invention is substantially horizontal during processing.
• the average flow of liquid metal in the device of the invention during treatment is also essentially horizontal.
• the device according to the invention can thus be inserted into a liquid metal flow system going from a holding pocket to the casting device via open chutes.
• the absence of a significant difference in level between the inlet and the outlet of the device makes it possible to simplify the liquid metal flow system and to avoid the risks of liquid metal overflowing.
• the theoretical free surface of the liquid metal being treated is indicated by a hatched line 26. It goes without saying that the free surface of the liquid metal is generally not flat inside the treatment compartment, in the sense that the gas bubbles cause deformation of this surface during treatment.
• the level (26) of the liquid metal is defined as being the average level of the free surface of the liquid metal which would be observed without the injection of the treatment gas.
• the level (26) of the liquid metal is typically substantially constant in the treatment compartment.
• the level (26 ') of the liquid metal in the upstream part (23) of said compartment is preferably typically substantially the same as the level (26 ") of the liquid metal in the downstream part (24) of said compartment .
• Said means of inlet (7, 9) and outlet (8, 10) of the liquid metal are arranged so that, during treatment, the level (26e) of the liquid metal at the inlet of the device is substantially the same as the level (26s) of the liquid metal at the outlet of the device.
• substantially the same level means that the difference in level is less than about 1 cm.
• the levels Ne and Ns of the bottoms (37, 38) of the feed (15) and discharge (16) spouts of the device of the invention are typically substantially at the same level.
• the levels Ne and Ns are typically between 20 and 50% of the average height H of the liquid metal contained in the treatment compartment during treatment.
• the orifices (9, 10) are preferably located near the bottom (28) of said compartment in order to promote more efficient treatment of the liquid metal and to simplify the emptying of the treatment compartment. More specifically, the bottom of the inlet (9) or outlet (10) orifice is preferably located at a distance of less than about 10 cm, and more preferably less than about 5 cm, from the bottom (28) of the upstream part (23) of the treatment compartment (20). In a preferred embodiment of the invention, the orifices (9, 10) typically correspond to one end of openings or conduits (7, 8) arranged in the opposite end walls (29, 30) of the pocket (2). These orifices can possibly be formed by more complex arrangements comprising, for example, a baffle.
• the pocket (2) typically comprises a metal box (3) and an inner lining (4) made of refractory material.
• the coating (4) can be preformed.
• the pocket advantageously comprises at least one drain (21), which is preferably located near the bottom (28) of the pocket (2).
• the drain can be located upstream or downstream of the filtration slab (s) (40, 41). It may be advantageous to provide a drain in the upstream part (23) of the treatment compartment and a drain in the downstream part (24) of the treatment compartment in order to ensure complete emptying of the bag after the treatment operation.
• the bottom (28) may possibly be inclined relative to the main axis (6) of the device.
• the pocket (2) is typically closed, in its upper part, using a removable cover (5).
• the cover typically includes a metal casing (34) and a refractory lining (35).
• the cover is advantageously provided with a gripping means (27) in order to be able to put it in place and remove it easily, generally using mechanized means.
• the device (1) advantageously comprises sealing means to avoid gas exchange between the inside and the outside of said compartment (20), such as a tight seal (36) between the cover (5) and the box ( 3).
• the treatment bag (2) and / or the cover (5) may be provided with a means for discharging (19) the treatment gas, such as a pipe made of refractory material.
• a means for discharging (19) the treatment gas such as a pipe made of refractory material.
• the “raw” liquid metal (17) enters the treatment compartment (20) via the inlet orifice (9) while the “treated” metal (18) leaves said compartment (20 ) through the outlet (10).
• the raw metal enters at the left end (E) of the device and the treated metal leaves at the right end (S) of the device.
• the inlet (9) and outlet (10) orifices of liquid metal are located on two opposite faces (29, 30) of the device.
• This configuration corresponds to a rectilinear arrangement. It is also possible, according to the invention, to arrange the inlet and / or the outlet on other faces of the device, so that they can be, for example, perpendicular or parallel to one another.
• the injection means (22, 22a, 22b) are preferably located in at least one side wall (32, 33) of the pocket (2).
• the injection means are advantageously placed on at least one of the lateral sides of the treatment compartment (20) of the pocket (2), and more precisely in at least one of the lateral walls (32, 33) of said compartment, which walls are essentially perpendicular to the flow of liquid metal. This choice makes it possible to have several injection means along the metal flow and thus to ensure greater treatment efficiency.
• the injection means (22, 22a, 22b) are typically placed in the two side walls (32, 33) of the treatment compartment (20).
• the injection means (22, 22a, 22b) are typically arranged in line and preferably located near the bottom (28) of the treatment compartment (20) in order to allow gas to be blown into most of the volume of metal. liquid included in the upstream part (23) of said compartment.
• the height of the injection means relative to the bottom of the treatment compartment is typically between 2 and 6 cm.
• injection means (22, 22a, 22b) only in the upstream part (23) of the treatment compartment (20). It is particularly advantageous to locate the injection means (22, 22a, 22b) in the flow of liquid metal emerging from the inlet orifice (9), so as to increase the volume of liquid metal actually treated.
• the injection means (22, 22a, 22b) are typically nozzles, which can be fixed or orientable.
• the injection means (22, 22a, 22b) are alternately in the two side walls (32, 33) of the treatment compartment (20), that is to say on either side of the treatment compartment. Said means are then not opposite, which allows the gas jets not to strike each other directly.
• the injection means (22a) which are placed on one side of said compartment (20) are offset longitudinally (that is to say in the long direction of the device) relative to the injection means (22b) which are placed on the other side of said compartment (20). This arrangement increases the effectiveness of the treatment.
• the injection means are typically in line on each side of the treatment compartment.
• the number of injection means is typically between 3 and 10 on each side of said compartment. They are typically spaced 10 to 20 cm apart.
• the injection means (22, 22a, 22b) are preferably such that they do not form protuberances inside the treatment compartment, so as to allow easy maintenance thereof.
• the injection means (22, 22a, 22b) take the form of nozzles, or similar systems, they may be recessed in the wall of said compartment.
• the tip of the nozzles is preferably made of a refractory material, such as sialon (aluminum and silicon oxynitride).
• the injection means (22, 22a, 22b) are normally fixed during the treatment, in the sense that they do not undergo movement of movement and / or rotation. Their orientation can however be variable in order to allow a finer adjustment of the efficiency of the injection of gas into the liquid metal.
• the injection means (22, 22a, 22b) can optionally make it possible to inject the treatment gas with a particular orientation relative to the bottom (28) of said compartment.
• the treatment gas is typically injected with an angle ⁇ of between 0 ° and 25 ° relative to the bottom (28).
• the injection means are preferably such that their total flow rate of treatment gas from the injection means is greater than approximately 5 Nm 3 / hour (typically between 8 and 10 m 3 / hour).
• This result can be obtained using a plurality of injection means located, preferably, near the bottom of said compartment (typically at a distance from the bottom of between 2 and 6 cm).
• Each filtration means (40, 41) is placed in the downstream part and inside the treatment compartment (20). It serves to prevent inclusions from passing into the flow of liquid metal (18) leaving the device.
• Each filtration means (40, 41) is preferably a filtration slab in order to allow an easy change thereof.
• the slab typically comprises a rigid ceramic foam, such as a CFF ("ceramic foam filter”), and is typically made of alumina.
• the porosity of the slab is preferably greater than 10 ppi ("pores per inch”)
• each slab is typically between 2 and 5 cm and its length L is typically between 30 and 50 cm.
• the device comprises a single filtration slab (40) whose width W is typically at least equal to the width Wo of said compartment and whose length L is typically at least equal to the height H of liquid metal in said compartment.
• the length L thereof is advantageously such that it extends almost to the cover (and therefore approximately equal to the height Ho of the internal cavity of the compartment (20)).
• the filtration slabs can be held in place by grooves in the wall of the treatment compartment.
• the device comprises at least a second filtration slab (41) disposed downstream of the first slab (40) (that is to say that the slabs ( 40, 41) are then arranged in series). These slabs are typically substantially parallel to each other. This variant of the invention can make it possible to change a tile without interrupting the treatment.
• the filtration slab (40) arranged so as to be entirely in the liquid metal during the treatment, which makes it possible to use the entire surface of the slab for filtration.
• Each filtration slab (40) can be tilted at an angle ⁇ relative to the vertical (that is to say relative to a line perpendicular to the main axis (6) of the compartment device), in order to d '' increase the filtration surface and the metal flow.
• the angle ⁇ is typically between 20 ° and 90 °.
• the slab can optionally be arranged horizontally (the angle ⁇ is then equal to 90 °).
• the device according to the invention may further comprise a baffle (42) between the upstream part (23) of said compartment (20) and the first filtration means (40), so as to limit turbulence near the surface of said first filtration means (40), as illustrated in FIG. 1.
• the filtration means are easy to change.
• the dividing line (25) between the liquid metal treatment zone by gas injection (23), upstream, and the filtration metal treatment zone (24), downstream, is approximate. It goes without saying that gas injection treatment can be extended slightly beyond this line.
• the length Lg of the upstream part (23) of the treatment compartment (20) typically corresponds to 30% to 90%, and preferably 50 to 80%, of the internal length Lo of said compartment.
• the length Lf of the downstream part (24) of the treatment compartment (20) then typically corresponds to 20 to 50% of the length Lo of said compartment.
• the invention Compared to installations which include a filter bag at the outlet of the degassing treatment tank, the invention has the advantage of reducing the length of the troughs and of reducing the exposure of the metal to the ambient air, which can including lead to hydrogen uptake.
• the preheating of the treatment device is done in a single operation, that is to say it is no longer necessary to preheat separately a gas treatment bag and a filtration bag, which allows reduce costs (in particular, a single burner can be used for this operation). Operating costs can also be reduced by the fact that coating changes need only be carried out on one treatment device.
• the device of the invention can be opened during treatment, without interrupting it, in order to remove the dross accumulated on the surface of the liquid metal and / or to change a filtration slab.
• width Wo of said compartment in the upper part between 0.2 and 0.4 m width Wo of said compartment in the upper part between 0.2 and 0.4 m (width Wo 'in the lower part of said compartment is typically 10 to 20 cm smaller);
• the interior volume of the Vo treatment compartment can be very small in comparison with known degassing treatment devices comprising a pocket (the Vo volume of the device according to the invention is typically between 0.1 m and 0.2 m while the known devices have an internal volume typically between 0.5 and 1 m).
• the device of the invention makes it possible to treat with high efficiency (typically higher at 40%) a volume V of liquid metal as low as 0.1 m 3 to 0.2 m 3 with a flow rate greater than or equal to 30 tonnes / hour.
• the compactness of the treatment compartment (20) and the high flow rate of the device of the invention make it possible to avoid cooling of the liquid metal during treatment.
• Process gas discharge means 0
• Upstream part of the treatment compartment 4 Downstream part of the treatment compartment 5
• Theoretical free surface of the liquid metal 6 'Level of the liquid metal in the upstream part of the treatment compartment 6 "Level of the liquid metal in the downstream part of the treatment compartment 6th Level of the liquid metal at the inlet of the device 6s Level of the liquid metal at the outlet of the device 7
• Lid gripping means 8 Bottom of the treatment compartment 9, 30 End walls of the treatment pocket 1 Wall of the bottom of the treatment pocket 2, 33 Side walls of the treatment pocket 4 Envelope metal of the cover 5 Refractory lining of the cover 6 Joint between the cover and the box 7 Bottom of the feed chute 8 Bottom of the evacuation groove 9 Volume of t gas treatment 0

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• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Mechanical Engineering (AREA)
• Organic Chemistry (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Manufacturing & Machinery (AREA)
• Manufacture And Refinement Of Metals (AREA)
• Electrical Discharge Machining, Electrochemical Machining, And Combined Machining (AREA)
• Casting Support Devices, Ladles, And Melt Control Thereby (AREA)
• Treatment Of Steel In Its Molten State (AREA)
• Filtration Of Liquid (AREA)
• Filtering Materials (AREA)
• Sampling And Sample Adjustment (AREA)

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• 2002
  • 2002-05-13 FR FR0205867A patent/FR2839518B1/fr not_active Expired - Lifetime
• 2003
  • 2003-05-06 ES ES03749924T patent/ES2271627T3/es not_active Expired - Lifetime
  • 2003-05-06 AU AU2003255561A patent/AU2003255561A1/en not_active Abandoned
  • 2003-05-06 WO PCT/FR2003/001399 patent/WO2003095686A1/fr active IP Right Grant
  • 2003-05-06 BR BR0310028-6A patent/BR0310028A/pt not_active Application Discontinuation
  • 2003-05-06 DE DE60308173T patent/DE60308173T2/de not_active Expired - Lifetime
  • 2003-05-06 RU RU2004136293/02A patent/RU2301274C2/ru not_active IP Right Cessation
  • 2003-05-06 AT AT03749924T patent/ATE338832T1/de active
  • 2003-05-06 PL PL372598A patent/PL198450B1/pl unknown
  • 2003-05-06 US US10/514,165 patent/US7648674B2/en not_active Expired - Lifetime
  • 2003-05-06 PT PT03749924T patent/PT1504130E/pt unknown
  • 2003-05-06 EP EP03749924A patent/EP1504130B1/de not_active Expired - Lifetime

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