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
  • C22B58/00—Obtaining gallium or indium
• • 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
  • C22B3/00—Extraction of metal compounds from ores or concentrates by wet processes
  • C22B3/20—Treatment or purification of solutions, e.g. obtained by leaching
  • C22B3/42—Treatment or purification of solutions, e.g. obtained by leaching by ion-exchange extraction
• • 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
  • C22B3/00—Extraction of metal compounds from ores or concentrates by wet processes
  • C22B3/20—Treatment or purification of solutions, e.g. obtained by leaching
  • C22B3/44—Treatment or purification of solutions, e.g. obtained by leaching by chemical 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
• • 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 present invention relates to a process for the separation of Ga-containing species of metal and non-metal species which form anions in acidic aqueous solutions by dialysis with anion exchange dialysis membrane.
• the process is particularly suitable for the pre-refining of gallium-containing process wastewater such as pickling solutions or
• Polisuspensions of GaAsferproduction to a
• the inventive method allows the processing of impure process effluents with ionic contaminant levels to a gallium solution with low impurity levels, which allows a conversion to a purified intermediate or direct further processing to elemental gallium.
• Gallium itself is only obtained in a few alumina smelters and in campaigns, which is why metal prices are subject to fluctuations between 200 and up to 2000 US $ per kilogram. Therefore, the recycling of gallium from production residues is of great strategic importance for reducing the demand for raw materials. Conventional methods for pre-refining gallium in
• Process effluents include, for example, precipitation processes or extraction processes.
• Main group eg arsenic acid
• a III-V semiconductor from a dissolved element of the third main group eg gallium
• This method comprises adjusting the pH of the effluent to about 9.5 to 12.5 by an alkali metal hydroxide and adding an alkaline earth metal hydroxide, whereby the
• Alkaline earth metal salt e.g., calcium arsenate
• the element of the third main group can be precipitated by adding a mineral acid and separated.
• a variant of the abovementioned US patent describes the precipitation of calcium arsenate from gallium-containing wastewaters. This process is very much through several process stages
• gallium and indium ions could be separated together by using N-dodecanoyl-N-methyl-3-aminopropionic acid (DMAP).
• DMAP N-dodecanoyl-N-methyl-3-aminopropionic acid
• the process requires the use of costly, organic chemicals in four neutralization and flotation stages that make the process uneconomical.
• the gallium-containing product is also heavily contaminated with organic chemicals.
• Liquid membrane process for Ga separation from an As-containing solution of wafer processing In a one-step process with good selectivity, gallium is extracted through a porous membrane impregnated with the organic extraction chemical PC88A. In this method, however, a regular bleeding of the extractant from the membrane occurs, so this loses its selectivity. The frequent and laborious regeneration of the membrane with extractant makes the entire process inefficient.
• Dialysis methods with solid ion exchange membranes are superior to the aforementioned processes since they consume practically no chemicals and the membranes used have a high stability. These processes can be found in
• Lye regeneration are established in the electroplating industry, while in the semiconductor industry so far hardly
• Kim describes in Separation Purification Technology 90, 2012, pp. 64-68 a diffusion dialysis process for the recovery of phosphoric acid from mixed waste solutions of the semiconductor industry. It has been found that diffusion dialysis with anion exchange membranes and subsequent distillation selectively separate phosphoric acid from metal-containing mixed acids can. The produced phosphoric acid can only be separated with 80% yield of aluminum and molybdenum species. The concentration of the recovered acid remains below 50%, so in a second step by vacuum distillation
• Zeidler describes in World of Metallurgy - ERZMETALL 67 (2014) the use of dialysis methods as an example of the separation of gallium and arsenic with uncoated membranes in spent pickling solution of GaAs wafer production.
• Ion species eg H2ASO4 " - arsenic acid ions
• Anion exchange dialysis membrane wherein an acidic feed stream to be separated has halide ions in a concentration of at least 2 mol / l and Ga ions in a concentration capable of forming gallium halide complexes, and wherein in the membrane Ga ion-containing species selectively
• Non-metal species are transported through the membrane.
• the feed side membrane layer shifts the
• Anion exchanger dialysis membrane for a Ga-retaining at least on the feed side has a modified membrane layer, which is produced by impregnation of the surface with weakly basic anion exchange groups.
• Anion exchanger dialysis membrane for a Ga-retaining at least on the feed side has a modified membrane layer, which is produced by targeted control of the membrane synthesis.
• Gallium halo complex is a gallium chloro complex.
• a dialysis cell for carrying out a method according to one of the preceding points, comprising a feed chamber and a dialysate chamber and anion exchange dialysis membranes, which separate the feed chamber and the dialysate chamber from each other.
• Dialysis cell according to item 17 having an anode and a cathode in the case of electrodialysis.
• Device having a plurality of dialysis cells according to one of the two preceding points, wherein the dialysis cells are arranged in cascade, in order to prevent selective separation of the impurities of the Ga solution in different
• the dialysis cells are preferably operated continuously in the opposite direction
• AnionenSermembran be retained when in a to be separated, acidic solution of the feed (feed stream) in the
• AnionenSermbran inflowing area halide ions in a concentration of at least 2 mol / 1 are contained in the feed.
• Halide ions disintegrate. At 0.3 mol / 1 Ga is the
• a dialysis method with the mentioned features can be used both as diffusion dialysis, as well as electrodialysis.
• arsenic is predominantly H 2 ASO 4 "at pH values 3 3, but stable metal halides form stable halogen complexes, despite the predominant presence in the membrane
• Halide concentration gradients in contrast to the GaX 4 ⁇ complex, are only decomposed stepwise and to a limited extent, so that the solution contaminates non-metal species such as
• Arsenic acid and metal complexes such as InCl, r and FeCl 4 "pass through the membrane while gallium is retained in a highly selective manner
• Membranes according to claim 5 increased by at least one order of magnitude (see membrane comparison in Fig. 6).
• purified feed can be obtained directly by electrolysis or by increasing the pH - which may be due to the addition of caustic, but alternatively already automatically
• Functional ion exchange is an exchange of different ions with charges opposite to and balancing the functional groups.
• Ion transport charge neutrality must be maintained, a directed charge transport by ion exchange can only take place when an equivalent of opposite charges is transported in the opposite direction. This would require strong external constraints (e.g., the application of a
• the ion exchange resins When sorbing ion pairs, the ion exchange resins absorb anions and cations to provide activity balance of the ions inside and outside the resin. The repulsive forces of the functional groups over similarly charged coions can be overcome to a limited extent.
• Anionic exchange resins can sorb H + ions by their high mobility at high concentrations, this allows, for example, the sorption of large amounts of acid.
• Membrane surface arises in the membrane a
• the functional principle of dialysis will be explained in more detail below.
• the principle of dialysis is based on selective ion transport through non-porous, with Ion exchange resins coated membranes. They are loaded on one side of the membrane and regenerated on the other side. As driving forces for mass transfer
• Diffusion dialysis relies on the passive diffusion of co-ion counterion pairs through special diffusion dialysis anion exchange membranes with weakly cross-linked polymers. It finds, for example, in the recovery of mineral
• the diffusion dialysis consumes water as the recipient medium (dialysate), as well as a small
• the membranes can be stacked to compact modules, so that the process works in principle very economical.
• Membrane is done by electromigration. The alternate
• Ion exchange resins targeted to produce permeabilities and selectivities for different application feeders. Diffusion dialysis membranes with degrees of crosslinking
• Controllability of the retention of Ga-containing species against permeation through the membrane of other metal and non-metal species to be separated is then significantly improved when the anion exchange membrane used is provided with a higher compared to the membrane backbone copolymer layer to the membrane accordingly to modify the surface facing the feed.
• the modified surface membrane layer is relatively thin, preferably in the thickness range up to 100 ⁇ m, more preferably up to 10 ⁇ m.
• the functional layers can also by a
• Anion exchanger groups which are produced by polycondensation of highly crosslinked layers on the surface or the partial decomposition of the strongly basic anion exchange groups on the membrane surface.
• Another possibility for producing the functional layer is the production by targeted control of
• the generated, pre-refined solution should have the highest possible Ga concentration and free from Be impurities such as arsenic acid or metal ions.
• the separation of arsenic acid and metal ions can be carried out in several dialysis stages, in which one or more impurities are selectively separated. It can be used above-mentioned anion exchange membranes, the
• One concept of the present invention is based on pH adjustment of etch effluents to pH ⁇ 3, preferably ⁇ 2. Should the pH increase above 3 due to the acid separation, gallium hydroxide will also precipitate in this embodiment, which sorptively binds arsenic acid. The precipitate can additionally cause a blocking of the membrane.
• anionic complex could be an anion exchange membrane
• the intensity of the characteristic chloro complex peak at 348 cm -1 increases with the chloride concentration, indicating the increase in GaCl 4 ⁇ concentration.
• the Raman spectrum was not shifted by chloro-complex formation, indicating a lack of stable transition complexes of gallium.
• Chloride concentration narrows, increases in intensity and in the characteristic of the tetrachloro complex resonance
• the membrane can not pass and thus do not reach the Eluatseite.
• Tetracholorokmplexe through the membrane and into the dialysate. Utilization of this effect allows the selective separation of Ga from other metals, e.g. In and Fe.
• Non-porous, ion-permeable membranes can be used to achieve the mentioned effects.
• the ion exchange resins may be composed of divinylbenzene copolymers or sulfonated fluoropolymers.
• anion exchange membranes contain functional groups (solid ions) with cationic charges that make the polymer swellable and ion-conductive.
• a membrane which contains as functional groups quaternary amines with short alkyl radicals.
• the exchange capacity (Ion Exchange Capacity, IEC) here is about 1.8 meq / g, based on a dry membrane.
• the membrane is made of PS-DVB polymer, the degree of crosslinking of the matrix is below 10% DVB.
• a coated anion exchange membrane of a fluoropolymer with quaternary amines type 1 is used.
• the method may e.g. take place in multi-chamber cells or plate modules or tube winding modules.
• Transport resistance of the diffusion boundary layers are kept low on both sides.
• the dialysis cells As already shown in FIG. 1, the dialysis cells
• Concentrations of the complexing halides can be operated with specific process parameters. These include the choice of membrane type and membrane area, the flow rates of feed and dialysate and the temperature and, in the case of electrodialysis, the current density.
• Example 1 Diffusion dialysis for the separation of Ga and As in batch plant
• coated diffusion dialysis anion exchange membranes in a batch plant 150 ml feed with 10 g / l Ga (0.143 mol / l) and llg / l As (0.147 mol / l) and a starting chloride concentration of 2.2 mol / l; 230 ml dialysate; 8 cm 2 membrane area).
• the coated membrane is of the Selemion APS4 type. It is based on a polysulfone skeleton with quaternary amines and is coated on the feed side.
• the uncoated membrane is of the Neosepta AFN type and is based on a PS-DVB resin
• Dialysis duration remains below 5 mg / l ( «0.072 mmol / l).
• the permeability of the arsenic acid is only slightly reduced in contrast to the permeability of gallium.
• Example 2 Ga A separation in a continuous countercurrent system
• Fig. 7 shows the design of a continuous
• Fig. 8 shows the dependency of the mole fraction of the indium (III) chloro complexes on the Cl concentration in an equilibrium.
• the initial concentration of In was 0.25 mol / l at 25 ° C and a pH ⁇ 2.
• the values are taken from: P Kondziela, J. Biernat (1975): “Determination of stability constants of Indium Halides Complexes by Polarography ", Electroanalytical Chemistry and Interfacial Electrochemistry 61, pp. 281-288, and I. Puigdomenech (2013):” Hydra-Medusa ", software with database for calculating chemical equilibria, software version August 2009, database Version January 2013,
• the feed used was an HCl solution with a concentration of 5 mol / l HCl, with which indium and
• Gallium present as chloro complexes In the experiment with Ga, an initial concentration of 0.15 mol / 1 Ga was used, in the experiment with indium, a starting concentration of 0.06 mol / 1 In was used. InCl-r is already stable in 0.5 mol / l HCl (see stability diagram of the indium chloro complexes in Fig. 8) and thus has a greater stability than GaCl4. " Thus, InCl 4 " can pass through the membrane much more easily than the latter corresponding gallium complex. The Ga transport out
• hydrochloric acid solution is therefore much slower than InTransport.
• Fig. 10 shows experimental results of Ga and Fe separation. Here, the concentration curves of iron and gallium in the dialysate are compared. The experiment was carried out in a two-cell cell equipped with a Selemion DSV membrane with a surface area of 25 cm 2 . The
• Feed volume was 200 ml and the dialysate volume was 300 ml.
• it is not quantifiable here how many chloride ions are already present in the feed solution as complexes of Ga and Fe.

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