FR2704770A1 - Method for separating fine particles of high specific gravity solid material from an emulsion, as well as device for carrying out the method. - Google Patents

Abstract

In the case of a process for separating fine particles of solid material of high specific gravity from an input product in the form of muddy or viscous emulsions, preferably oil-water emulsions, the mixture is continuously poured. input product by mixing it with water. The fine particles of solid material with a high specific weight which must be separated settle to the bottom in a sedimentation zone of this product stream. Superimposed on the product flow is a fluid flow oriented transversely with respect to the latter, which passes over the lateral limits of the latter and essentially carries away the components of the product flow present above the fine particles of the product. solid matter which is deposited at the bottom, so that the separation is done using only water and therefore without gassing, while preserving the environment. Furthermore, the document describes a device for implementing the method. The method and the device can be specially used for environmentally friendly treatment of rolling scale.

Description

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DESCRIPTION

  The invention relates to a process for separating fine particles of high specific gravity solid material, preferably metals, from an input product in the form of muddy or viscous emulsions, preferably oil-water emulsions,

  as well as a device for implementing the method.

  The steel industry produces what should be called rolling mills. They result from the rolling of steel and iron products or from the cooling of these products during a rolling operation using specific oils, water and emulsions. The scale is muddy in nature and consists of a mixture of iron alloy particles, oils and water, the composition of which is variable, the iron alloy particles having a fine and extremely fine size,

sometimes lamellar in shape.

  In order to make good use of the quantity of metal contained in the scale, a known method provides for dosing this quantity during the preparation of the ore (sintering tunnel) in front of the blast furnace, mixing it with the ore, then crush, dry and preheat in the sintering tunnel. During drying and heating, the scale releases oil vapors which are easily flammable. In the exhaust gas cleaning systems of the sintering tunnels which were usual in the past and which were made in the form of

  cyclone dust collectors, the exhaust gases could not ignite.

  In the course of improving environmental protection, the exhaust gas purification installations of the sintering tunnels were equipped with electrostatic precipitators. However, the bursting of sparks in the electrostatic precipitators can cause uncontrolled ignition of the oil vapors contained in the exhaust gases. Numerous fire and explosion damages have already been caused. For this reason, it is not currently possible to reuse the

  scale in their original state.

  To reuse the scale, it should be treated beforehand, so that the prepared metal components contain only a small amount of flammable oil. In this case, the limit value is located, for example. in

  the order of magnitude less than / equal to 0.2% by weight.

  To treat the scale, thermal methods according to which heating and combustion of the quantity of oil are not carried out directly have already been suggested. This kind of process is very expensive due to the high cost of development

  appropriate facilities and the necessary exhaust gas cleaning.

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  In addition, the implementation of this kind of thermal process producing exhaust gases is subject to strict anti-pollution standards and a procedure

  which further contributes to increasing the cost.

  The object of the invention is to create a method of the kind mentioned in the introduction as well as a device for implementing the method, which make it possible to establish the limit values for the oil cited as an example, do not have d '' thermal stages producing exhaust gases, for which the emission tax is

  reduced accordingly and therefore lower operating costs.

  This goal is achieved by the characteristics mentioned in the section

  Characteristic of claim 1. The subclaims contain

  suitable embodiments of this process and describe an adequate device for the implementation

  work of the method according to the invention.

  The invention is based on the idea of carrying out the separation in a process operating continuously by adding a fluid, preferably exclusively water, to the input product to be separated, the separation being effected by the fact that one produces a flow of continuous product containing the emulsion to be separated, at the bottom of which the fine particles of solid material with high specific gravity are deposited, and which are superimposed on the deposition zone (sedimentation zone) and / or on the zone which follows the product flow downstream of the latter a fluid flow oriented transversely to the product flow (preferably also water). This transversely oriented fluid flow carries only part of the product flow and leads it to a transverse flow, while a product flow is provided for the product flow itself. The part of the product flow which is carried away by the fluid flow constitutes the upper part or the part of the product flow turned towards the surface which contains (no longer) fine particles of solid material with high specific weight. This is due to the fact that the fluid flow passes over the terminal side of the lateral limit of the product flow which is opposite to its supply side. By analogy with mechanics, this process could be designated as a "shear separation" of the part of the product flow containing the fine particles of high specific gravity solid which have settled at the bottom and the part of product flow no longer containing these fine particles of solid matter

with high specific weight.

  In an appropriate embodiment, it is possible to provide, on the one hand, for the process to take place continuously in a repeated manner, so that the fluid flow passing over the lateral limit of the product flow is distributed in one other or in

  several other secondary product flows and a residual fluid flow passing through-

  above its (their) lateral limit (s). In addition or instead, it is possible to provide that a part of the fine heavy heavy particles which is not separated during the first pass is again continuously mixed with the input product of the

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  process, which does not require extracting the water beforehand. The process is continuous and can be designed for all capacities. The water component can largely circulate in a circuit in order to preserve the environment. Excess amounts of oil-containing water can be easily treated for reintroduction or can be routed to treatment facilities

  existing, where applicable, in steel plants.

  - The method according to the invention is capable of providing the limit values for the oil contained in the wet metallic components, does not produce gas

  and works while respecting the environment.

  Other details, characteristics, advantages of the present invention are

  indicated below in the description of an exemplary embodiment in support of the drawings

  diagrams attached in appendix. The figures show: Fig. 1 a schematic representation of the complete progress of a process according to the invention; Fig. 2 a schematic representation of a device for implementing the method

of separation proper.

  In fig. 1, 1 denotes a metered supply of scale in the form of mud. A metering device shown diagrammatically has the reference number 2. The metering devices shown elsewhere in FIG. 1 with the corresponding symbol do not have a specific reference number. The scale is mixed with primary water 3 dosed from a water tank. The mills 1 and the primary water 3 feed a mixing tank designated by 4. A metered withdrawal of the mixture composed of millings and primary water is designated by 5. This mixture is brought to the inlet 6 (fig. 2) of a separation body generally designated by 7. The structure of the separation body 7 is described in more detail below with reference to FIG. 2. Secondary water 9 dosed from. a water tank is brought to an inlet 8 of the separation body. In addition, fluid water 11 metered from a water tank is supplied to an inlet 10. The separation body 7 can perform an alternating movement in the direction of the double arrow 13 under the action of a generator

  of oscillations 12, which gives it an oscillating movement.

  The separation zones which form in the separation body 7 during the course of the process are designated by I, II and III. I constitutes a flow zone for the metallic component / water components, II is a flow zone for the water / residual oil components / residual metal component and zone III is a flow zone for the oil / water components residual. The constituent which flows from flow zone I (metallic component / water) is designated by 14 and feeds a decanter designated by 15. The constituent which flows from flow zone II (water / residual oil / residual metal component) is designated by

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  16 and feeds a decanter designated by 17. The constituent which flows from the flow zone mI (oil / residual water) is designated by 18 and feeds a decanter designated by 19. Water is withdrawn in metered quantities from the decanters 15, 17 and 19 in the direction of arrow 20 and feeds a water tank (not shown). The mixture of metal component / oil / water is withdrawn in a metered manner from the decanter 17 in the direction of the arrow 21 and mixed with the scale 1.22 denotes a withdrawal of the aqueous oily component from the decanter 19 which leads to a treatment installation (not

  shown). 23 denotes the withdrawal of the wet metallic component.

  The separation body 7 shown in FIG. 2 has an oblong separation surface 24 which is arranged in the longitudinal direction at an angle (x with respect to the horizontal plane and with an angle B with respect to the transverse plane, so that the surface partition 24 is arranged diagonally and at an angle to the horizontal As mentioned above, the separation surface 24 can be moved with an oscillating movement in the direction of the double arrow 13. The separation surface 24 has beads retaining 25, 26,27,28 and 29. On the side opposite the retaining bead 25 in the longitudinal direction is provided a feeding device 30 extending upwards above the separation surface 24, which has a wall 31 extending upwards perpendicularly to the separation surface 24. Thus several longitudinally extending channels are produced on the separation surface 24, at namely a flow channel 32 for the product flow and flow channels 33, 34, 35 and 36 for the secondary product flows. The mixture 5 (scale / primary water) feeds the flow channel 32. This mixture enters the flow channel 32 by a flow 37. Above the flow 37, the flow channel 32 is supplied with secondary water 9 (flow 38). There is thus formed a product flow designated by 39. A fluid flow is superimposed in the direction of the arrow 40 on the product flow 39. This fluid flow is produced by the fact that the fluid water 11 exits by flows 41 and passes over the opposite retaining bead 25 (and

  over the other retaining beads which follow it).

  The separation operation takes place as follows: The tines 1 can be oily (high oil content) or thin (low oil content). The quantity of primary water to be added to the mixing tank 4 is measured according to its oil content. The mixture 5 is then withdrawn in a metered manner and charged with a quantity of secondary water 9 on the separating surface 24 with oscillating movement. By adding secondary water, a product flow 39 of the mixture 5 with the secondary water is formed on the separation surface 24 in the direction

  longitudinal of the flow channel 32.

  Since water is added to the scale, the portion of metal with a higher specific gravity can settle at the bottom of an area of

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  sedimentation of the product flow 39. The oscillating movement in the direction of the double arrow 13 makes it possible, however, to ensure that the mixture of secondary water 9 and

  mixed material 5 passes through flow channel 32 in the direction of flow.

  The actual separation operation is caused by the fluid water 11 which flows over the product flow 39 in the direction of flow 40 and which passes over the retaining bead 25 (and, in the case of the embodiment shown, also over the other retaining beads). In doing so, there is formed between the fluid water 11 and its main flow direction 40 and the product flow 39 a "separating shear flow". This is favored by the oscillating movement 13 and the longitudinal and transverse inclination of the separation surface 24 relative to the horizontal. The upper face of the separation surface 24 is covered with a mixture of plastic and rubber which prevents fine and very fine particles of metal from forming colloids, despite their partially lamellar shape, and which guarantees the particles of metal a free passage in the direction

longitudinal, as desired.

  In the embodiment shown, essentially three zones are formed on the separation surface 24, namely: Zone I for the constituent metallic component / water, in particular primary and secondary water; Zone II for the water component / residual oil component / residual metal component and

  Zone III for the aqueous oily component.

  The components 14, 16 and 18 which flow are collected separately by collecting or settling tanks 15, 17 19. In the tanks, the aqueous component which is each time obtained is deposited at the top / in the middle / at the bottom depending the type of liquid / mixture. The water is withdrawn in a metered manner from each of the tanks (water withdrawal 20) is brought into a water tank which takes care of the supply of primary water, secondary water and fluid water, so that he is forming

thus a water circuit.

  The purified, oil-poor metal component can be drawn from the settling tank 15 from below (reference number 23). After having extracted the water therefrom, the quantity of water / residual oil / metallic component 16 component (zone 2) which has not been separated is brought back to the loading of the tracks 1 for a new separation (reference number 21). After extracting the water, the residual aqueous oily component from the tank 19 is removed from the process to be treated

  later (reference number 22).

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Claims (13)

Claims   1. Process for separating fine particles of high specific weight solid material, preferably metals, from an input product in the form of muddy or viscous emulsions, preferably oil-water emulsions, characterized in that the input product, in a liquid state allowing fine particles of solid matter to settle at the bottom, is continuously subjected to a flow of product delimited in width so that fine particles of solid matter with high specific weight can descend in a sedimentation zone of the product flow and so that the product flow opens into a product flow, and in that the product flow is continuously superimposed, in the sedimentation zone and / or downstream of the product flow, a fluid flow brought by a longitudinal side of the product flow and oriented transversely with respect to the product flow, which opens onto the longitudinal side opp daring at the feed side in at least one transverse flow passing over the lateral limit of the product flow, the fluid flow which passes over the lateral limit continuously carrying the components which are above the product flow fine particles of solid matter by weight   specific high that settled to the bottom.   2. Method according to claim 1, characterized in that the flow of   product is subjected to an oscillating movement going in the direction of flow.   3. Method according to claim 1 or 2, characterized in that the input product is made fluid by adding primary water, in that the product flow is caused by adding secondary water and in that the flow fluid is produced in   adding water transversely to the product flow to the input product.   4. Method according to one of claims 1 to 3, characterized in that the   fluid flow passing over the lateral limit of the product flow is divided at least into another secondary product flow and into a residual fluid flow passing over the lateral limit of the latter.   5. Method according to one of claims 1 to 4, characterized in that the   fine particles of solid material with a high specific weight which are, if necessary, still present in the evacuated fluid flow again supply the product flow,   knowing that beforehand, no water is extracted from the fluid which flows back.   6. Method according to one of claims 3 to 5, characterized in that   the water used by the process largely circulates in a circuit.   7. Device for implementing the method according to one of   Claims 1 to 6, characterized in that at least one flow channel (2? for the   product flow (39) is provided on a separation surface (24), channel which has at least one supply orifice (41) for the fluid flow (40) on a side boundary 7 2704770   longitudinal and the opposite lateral limit of which is formed by a retaining bead (25), in that a flow for the product (14) follows the separation surface (24) in the direction of flow of the product flow (39) and below the retaining bead (25) and in that at least one drain (16, 19) for the fluid flow is provided for the fluid flow (40) passing over the retaining bead (25 ). 8. Device according to claim 7, characterized in that on the separation surface (24) is arranged, in addition to the flow channel (32) and parallel to the latter, at least one flow channel (33 or 34 , 35, 36) additional, which is delimited on both sides by retaining beads (25, 26 or 26, 27 or 27, 28 or 28, 29).   9. Device according to claim 7 or 8, characterized in that the separation surface (24) is arranged on the upper face of a separation body (7) and in that the separation body (7) is connected to a device (12) for producing   an oscillation (13) directed in the longitudinal direction of the flow channel (32).   10. Device according to one of claims 7 to 9, characterized in that   of the surface area (24) is arranged, both in the longitudinal direction of the flow channel (32) and transversely with respect to the longitudinal direction of the channel   flow (32), with an acute angle (ca or B) relative to the horizontal.   11. Device according to one of claims 8 to 10, characterized in that   the retaining beads (25, 26, 27, 28, 29) are produced with different lengths   in the flow direction of the product flow (39).   12. Device according to one of claims 7 to 11, characterized in that   the upper face of the separation surface (24) has a coating for   prevent solid matter particles from forming colloids.   13. Device according to claim 12, characterized in that the   coating is a mixture of plastic and rubber.