Classifications

• • 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
  • C22B1/00—Preliminary treatment of ores or scrap
  • C22B1/005—Preliminary treatment of scrap
• • 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
  • C22B7/00—Working up raw materials other than ores, e.g. scrap, to produce non-ferrous metals and compounds thereof; Methods of a general interest or applied to the winning of more than two metals
  • C22B7/006—Wet processes
• • 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
  • C22B7/00—Working up raw materials other than ores, e.g. scrap, to produce non-ferrous metals and compounds thereof; Methods of a general interest or applied to the winning of more than two metals
  • C22B7/006—Wet processes
  • C22B7/007—Wet processes by acid leaching
• • 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
  • C22B7/00—Working up raw materials other than ores, e.g. scrap, to produce non-ferrous metals and compounds thereof; Methods of a general interest or applied to the winning of more than two metals
  • C22B7/006—Wet processes
  • C22B7/008—Wet processes by an alkaline or ammoniacal leaching
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
  • C23F1/00—Etching metallic material by chemical means
  • C23F1/02—Local etching
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
  • Y02P10/00—Technologies related to metal processing
  • Y02P10/20—Recycling

Definitions

• the invention relates to a method for detaching coatings from scrap, wherein the scrap is brought into contact with a liquid.
• Scrap in particular steel scraps, are often provided with a coating which serves to protect against corrosion or special physical and optical surface effects.
• the products from which the scraps are obtained after use can, for example, be coated electrolytically, in the hot-dip process or by plating with a layer of other metals and / or treated with organic compounds, for example lacquered or foil-laminated.
• organic compounds for example lacquered or foil-laminated.
• steel is provided as a corrosion protection with a zinc layer, so that considerable amounts of galvanized steel scrap incurred.
• the only economic disposal and recycling route for such hybrids has hitherto been the remelting of the scrap in the electric arc furnace or in foundry furnaces, here preferably in cupola furnaces.
• This object is achieved by a method for detaching coatings of scrap, wherein the scrap with a liquid in Contact is brought and the scrap is moved during the removal of the coating in a conveyor trough of a vibratory conveyor along a conveying direction from the inlet end to the outlet end of the conveyor trough.
• the invention is primarily based on using a vibratory conveyor with a conveyor trough, also known as a vibrating trough, to carry out the detachment of the coating herein.
• vibratory conveyors are mechanical conveyors for bulk materials of different types, in which the medium to be transported is moved by means of vibrations.
• a typical vibratory conveyor moves for transport obliquely upwards in the conveying direction and back, d. H. the movement comprises a vertical component and a horizontal component in the conveying direction. In this way, the conveyed material is thrown upwards and, after the oscillating conveyor itself has moved back, hits again in a region lying closer to the outlet end of the conveying trough in the conveying direction.
• the conveyed material placed at the entrance end "jerks" gradually towards the exit end by being thrown upwards and towards the exit end by the vibrations an exemplary vibration frequency of 10-16 Hz and a further movement of the conveyed material per oscillation in the range of 5-10 mm thus results in a transport speed of 3 m / min and more.
• a vibrating conveyor is also understood to mean a vibrating chute.
• the vibratory chute moves only back and forth, ie only in the horizontal, but without vertical component. Instead of a "throw" of the conveyed material, with each oscillation it slips a little farther in the direction of conveyance.With each oscillation, the conveyor trough first moves in the conveying direction before being accelerated in the opposite direction at the end of this movement Inertia of the scrap parts each slips further in the conveying direction, since the process is constantly repeated with high frequency, resulting in a significant movement in total Conveying direction.
• the conveyor trough of a vibratory conveyor essentially consists of a largely flat bottom and lateral, longitudinally extending boundaries.
• the conveyed material is applied to the conveyor trough at one end (the entry end) and further moved to the other end (the discharge end) in the conveying direction.
• the conveying direction is hereby meant, the term "lateral" thus refers to the direction orthogonal to the longitudinal direction.
• Vibratory conveyors are robust and largely maintenance-free. In contrast to other conveyors, congestion is relatively rare, since vibratory conveyors usually "shake themselves free” again.
• the process can be operated continuously, since the scrap to be treated is simultaneously moved on and reacted with the liquid. Accordingly, the contact time between scrap and liquid is largely predetermined, since the scrap for its movement from the inlet end to the outlet end depending on the length of the vibratory conveyor, vibration frequency and pulse per vibration requires a certain time.
• the control of the contact time of scrap and liquid allows, for example, in the dezincification of Stahlsch rotten using sulfuric acid to keep the unwanted iron entry within acceptable limits.
• a vibrating conveyor a continuous relative movement between scrap and Liquid brought about, which also promotes the detachment of the coating.
• the bulkhead of the scrap can be increased, because when using a vibrating conveyor also concealed scrap from other scrap parts due to the movements in contact with the liquid. Preference is given to vibrations with a vertical component, ie in the conveying direction and upwards and backwards, since in the case of the scrap particles produced in this way, the position is changed and particularly strong relative movements take place.
• the conveyor trough itself is spared, because the sliding friction is kept low by the constant throwing movements.
• the invention relates in particular to the detachment of coatings of steel scrap, but is not limited thereto.
• the removal of zinc coatings serving as corrosion protection has a particularly great economic significance in the case of steel scrap.
• the automotive industry for example, considerable quantities of galvanized steel scrap are produced; at the same time, the steel and foundry industry demand almost or completely de-iced scrap for recycling.
• zinc is also a valuable metal, the recovery of which offers considerable economic potential, but is also desirable in terms of environmental protection and the conservation of resources.
• the detachment of the coating can be carried out in particular by means of an acidic aqueous solution, the use of sulfuric acid being preferred. However, it is of course also possible to use it within a process in which work is carried out with an alkaline-aqueous solution.
• the liquid used for the removal of the coating may also be organic solvents, for example paint remover for removing paint or the like.
• the scrap is sprayed with the liquid during the detachment of the coating.
• specially designed nozzles are used, which can be arranged in particular above the vibrating conveyor filled with scrap. possible
• the spraying of the entire surface is supported by the fact that the scrap parts constantly change their position during the shaking process, so that ultimately the entire surface is sprayed.
• the dezincification process is supported by the dynamics of the liquid jet itself.
• the liquid with which the coating is removed from the scrap should be absorbed.
• the liquid flows out at the outlet end of the conveyor trough, if this is open.
• the Trapped liquid can be further processed accordingly.
• the detached metal can be recovered electrolytically.
• a method can be carried out in which the scrap is passed through a corresponding immersion bath.
• the scrap dips into the liquid during the detachment of the coating.
• the conveyor trough thus contains a certain amount of liquid through which the scrap parts are moved.
• the oscillation frequency and / or the oscillation amplitude must be adjusted.
• the transport speed depends u. a. from the amount of liquid and the viscosity of the liquid.
• the inlet end and outlet end should each have a liquid-tight barrier.
• the conveyor trough thus represents a shallow tub, within which the liquid is and through which the scrap parts are moved. The escape of liquid is prevented by the border of the conveyor trough. Since there is a liquid-tight barrier at the exit end, the scrap parts can not simply fall off the conveyor trough, but must be actively moved out, for example by means of magnets. Can be used, for. B. overhead magnetic rollers / magnetic tapes. Of course, alternatives are also conceivable, for example lifting out by means of gripping devices, grids with a drip-off device or baskets which have openings on the underside, so that the liquid can run out.
• the liquid for detaching the coating from the scrap should be exchanged controlled, for example by pumping. For example, it is possible to continuously measure how high the concentration of the metal ions detached from the scrap is in order to always expel just enough of the liquid so that the metal ion concentration is within the desired range.
• the exchanged liquid is then usually reprocessed, ie detached metal ions are recovered in metallic form, in particular by electrolysis.
• the zinc in the case of dezincing with the aid of sulfuric acid, it is also possible to recover the zinc as zinc sulfate.
• a high zinc sulfate-enriched suspension may be used for further zinc sulfate production or direct reuse on electrolytic galvanizing equipment.
• the precipitation of the zinc sulfate is possible by cooling the mother liquor to 10 ° C.
• concentration precipitation / temperature precipitation zinc sulfate can be freed from the sulfuric acid solution by a centrifuge so that a free-flowing / shovel product of zinc sulfate heptahydrate low residual moisture of preferably 3 - 5%.
• the zinc sulfate heptahydrate can also be calcined at the monohydrate plant.
• the bottom of the conveyor trough is formed horizontally, which is associated with advantages in that vibratory conveyor conveyed material move substantially in one plane, ie a vibratory conveyor normally operates in a horizontal direction. But it is also possible to form the vibratory conveyor so that the bottom of the conveyor trough slightly increases in the conveying direction, preferably by about 3-5 °. In this way it is achieved that the Liquid in the forward direction seen in the conveying direction of the vibrating conveyor, ie the direction of the inlet end, accumulates. When the scrap is now moved in the conveying direction, it finally emerges upwards through the liquid surface.
• the outlet end need not necessarily be closed, but rather it is sufficient to provide a liquid-tight barrier at the inlet end while the outlet end is open.
• the direction exit end promoted scrap parts can then simply fall off the conveyor trough; a special lifting with the help of magnets o. ⁇ . Is then not necessary.
• the scrap parts thus move first through the liquid and in the further course through the ambient atmosphere.
• the scrap can be sprayed with the liquid in the area in which it is no longer within the liquid when additional nozzles are provided for spraying in the downstream direction of the conveying channel seen in the conveying direction.
• the inclination of the conveyor trough can be advantageously adjusted as needed, so that the slope of the bottom of the conveyor trough is variable in the conveying direction.
• Vibratory conveyors used for the process typically have a flat bottom conveyor trough, the trough having sidewalls. Depending on whether the treatment with the liquid in the dive or Spray method is to be performed, more walls may be provided at the longitudinal ends.
• a suitable for the process vibratory conveyor can, for. B. depending on the required transport capacity have a conveyor trough with a length of about 6 - 8 m, the flat bottom is 1 - 2.5 m wide.
• the device for carrying out the method may have means for adjusting the temperature, so that the liquid is optimally tempered.
• a sulfuric acid solution to accelerate the Entzinkung of steel scrap to 40 ° C - 60 ° C (possibly even above) tempered, while in the case of a basic Entzinkung i. d. R. higher temperatures of 85 ° C and more are required to allow the dezincification in reasonable time at all.
• the heat produced by the dilution of concentrated sulfuric acid to a nominal concentration of 15-35% can be used to achieve the desired process temperature.
• the process can be operated largely autothermally.
• the times to be set to remove the coating vary.
• the type of galvanizing electrolytic, hot-dip galvanized, galvannealed, galvanized
• the thickness of the applied zinc layer and also the type of scrap processing upstream of the Entzinkung play a role.
• Largely untreated scrap will require a longer time for complete dezincification, while comminution of the scrap by cutting, shredding, etc. by providing additional attack surfaces for acceleration.
• it is advantageous for the use of a vibrating conveyor if the individual scrap parts have a size that allows unproblematic conveying by means of a swinging motion. The conveying speed can also be adjusted as needed.
• the conveying speed can be reduced, if this is necessary to achieve a complete detachment of the coating.
• the horizontal conveying speed can be controlled to 0, so that the scrap is held in place for a while and is not conveyed to the discharge end. It is even possible a temporary movement opposite to the conveying direction. Once the desired result in terms of the release of the coating is achieved, the scrap parts are then transported further towards the outlet end.
• the vibration can also be set up so that the conveyor trough performs only a movement in the horizontal without vertical portion, d. H. it only results in a forward movement of the scrap parts.
• the movement of the conveyor trough in this case is that of a vibrating chute.
• Another advantage of the treatment of the scrap within a vibrating conveyor is that touch during the shaking individual scrap parts regularly and in the case of sharp-edged parts, the surfaces are mutually injured. Such damage to the coating simplifies the detachment, since the coating is often a passivation layer. Relative movements of the scrap pieces to each other are also brought about by the fact that the speed differs in the conveying direction depending on baingutière. The relative movement results from the different damping of the vibration excitation in connection with different friction processes on the dumping height. With increasing bed height, therefore, there are always stronger shifts between the layers, which is reflected in the fall in the average conveying speed. Especially with flat scrap pieces, z. B.
• stamping waste from Neuschrott it may be useful to bring about rotation of the scrap parts about its axis, so that all sides of the scrap uniformly from the liquid be wetted.
• one or more steps can be installed in the bottom of the conveyor trough, so that overall the bottom of the conveyor trough has a lower level at the outlet end than in the region of the inlet end.
• a given piece of scrap is conveyed through such a step, it falls off that step, rotating about its own axis and then resting on another side on the bottom of the vibrating conveyor than before. This is of particular importance when the scrap is sprayed with the aid of nozzles arranged above the vibrating conveyor, so that all regions come into contact with the liquid even in the case of flat scrap parts.
• the height of the steps ie the drop height can be set differently depending on the size of the scrap parts to be processed.
• the vibratory conveyor may also include means for adjusting the height of the steps.
• a rotation of the scrap parts about its own axis takes place several times.
• Another way to make the scrap parts move around their axes is to place additional obstacles within the conveyor trough in the conveyor path where the pieces of scrap rotate in a particular direction, driven by the vibrations. For example, elevations on the bottom of the conveyor trough can ensure that a scrap part rises in the conveying direction and then falls onto its underside. Subsequently, further sides of the scrap part are accessible to the liquid.
• the conveyor trough of the vibrating conveyor should be lined in such a way that on the one hand it withstands the mechanical loads on the scrap parts and on the other on the liquid.
• the conveyor trough In the case of using an acidic aqueous solution, for example, the conveyor trough must be sufficiently acid-resistant. Suitable materials are high-alloy, wear-resistant steels or nickel-based alloys. In addition, these increase the electrode potential in the zinc conveying material trough system and thus contribute to an additional acceleration of the dezincification process.
• dezincification in acidic solution can be additionally accelerated, in which the sulfuric acid solution is preloaded with zinc ions.
• concentration of zinc ions in the acidic solution is preferably about 10 to 100 g / l.
• a zinc solution can be used, which comes from the primary zinc production of a zinc smelter.
• the Entzinkungs processes the concentration of zinc ions to be further increased, so that a subsequent electrolysis for the production of zinc is associated with a correspondingly higher yield.
• an oil in particular a drawing oil or a wash oil
• concentration of the oil in an acid dezincing should be about 0.1 to 3% by weight, based on the steel scrap.
• the dezincification itself is virtually unaffected by the presence of the oil.
• the oil can optionally be separated off via a phase separation and reused.
• the oil content should be kept low, so appropriate precautions should be taken.
• Fig. 1 A vibratory conveyor in the side view according to a first embodiment
• Fig. 2 the conveyor trough of the vibrating conveyor
• FIG. 3 shows a vibratory conveyor in the side view according to a second embodiment
• Fig. 4 the conveyor trough of the vibratory conveyor
• FIG. 5 shows a vibratory conveyor in the side view according to a third embodiment.
• the vibratory conveyor 1 has a conveyor trough 2, in which individual scrap parts 3 are located.
• the vibratory conveyor 1 is driven by the oscillating drive 4, which generates a movement in the direction of oscillation 5, ie the scrap parts 3 are thrown upwards and to the right in the drawing, so that after each oscillation they are displaced to the right by a certain distance back into the conveyor trough 2 arise.
• the conveyor trough 2 has an inlet end 7 and an outlet end 8.
• the scrap introduction is symbolized by the arrow 10, the scrap removal, for example by means of magnets, with the aid of the arrow 11.
• the bottom 9 of the conveyor trough 2 is flat.
• the scrap parts 3 are thus conveyed within the liquid from the inlet end 7 to the outlet end 8. They come with the liquid from all sides in contact, so that a virtually complete removal of the coating takes place.
• this has both at the inlet end 7 and at the outlet end 8 each have a liquid-tight barrier, so that the conveyor trough 2 has the overall shape of a trough.
• FIG. 3 an alternative embodiment of the invention is shown, with respect to the movement of the scrap parts 3 through the conveyor trough 2, the same applies to the first embodiment.
• the scrap parts are not below a liquid surface 13, but they are sprayed from above through nozzles 14 with the liquid. Since it is not a dip in this case, the outlet end 8 (and possibly also the inlet end) may be open. Accordingly, the scrap parts 3 am Exit end 8 according to the arrow 11 simply fall down from the conveyor trough 2 to be caught behind the conveyor trough 2.
• this alternative embodiment is shown in frontal view, it being recognized that there is no liquid surface 13 here.
• FIG. 5 shows a third embodiment, which basically corresponds to the embodiment according to FIG.
• a step 15 is provided within the bottom 9.

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• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Geology (AREA)
• General Life Sciences & Earth Sciences (AREA)
• Manufacturing & Machinery (AREA)
• Environmental & Geological Engineering (AREA)
• Life Sciences & Earth Sciences (AREA)
• Organic Chemistry (AREA)
• Metallurgy (AREA)
• Geochemistry & Mineralogy (AREA)
• Manufacture And Refinement Of Metals (AREA)
• Refinement Of Pig-Iron, Manufacture Of Cast Iron, And Steel Manufacture Other Than In Revolving Furnaces (AREA)
• Carbon Steel Or Casting Steel Manufacturing (AREA)
• Processing Of Solid Wastes (AREA)

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• 2011
  • 2011-02-17 DE DE201110011532 patent/DE102011011532B3/de not_active Expired - Fee Related
• 2012
  • 2012-02-16 EP EP12709786.3A patent/EP2675929B1/de active Active
  • 2012-02-16 CN CN201280018155.7A patent/CN103502483B/zh not_active Expired - Fee Related
  • 2012-02-16 ES ES12709786.3T patent/ES2662745T3/es active Active
  • 2012-02-16 US US13/261,715 patent/US9487844B2/en active Active
  • 2012-02-16 JP JP2013553837A patent/JP2014506959A/ja active Pending
  • 2012-02-16 WO PCT/EP2012/000683 patent/WO2012110239A1/de not_active Ceased

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