Classifications

• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B19/00—Selenium; Tellurium; Compounds thereof
  • C01B19/004—Oxides; Hydroxides
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B09—DISPOSAL OF SOLID WASTE; RECLAMATION OF CONTAMINATED SOIL
  • B09B—DISPOSAL OF SOLID WASTE NOT OTHERWISE PROVIDED FOR
  • B09B3/00—Destroying solid waste or transforming solid waste into something useful or harmless
  • B09B3/30—Destroying solid waste or transforming solid waste into something useful or harmless involving mechanical treatment
  • B09B3/35—Shredding, crushing or cutting
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B09—DISPOSAL OF SOLID WASTE; RECLAMATION OF CONTAMINATED SOIL
  • B09B—DISPOSAL OF SOLID WASTE NOT OTHERWISE PROVIDED FOR
  • B09B3/00—Destroying solid waste or transforming solid waste into something useful or harmless
  • B09B3/70—Chemical treatment, e.g. pH adjustment or oxidation
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B19/00—Selenium; Tellurium; Compounds thereof
  • C01B19/02—Elemental selenium or tellurium
• • 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
  • C22C—ALLOYS
  • C22C28/00—Alloys based on a metal not provided for in groups C22C5/00 - C22C27/00
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C30/00—Alloys containing less than 50% by weight of each constituent
  • C22C30/02—Alloys containing less than 50% by weight of each constituent containing copper
• • 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
• • 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
  • Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
  • Y02W30/00—Technologies for solid waste management
  • Y02W30/20—Waste processing or separation
• • 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
  • Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
  • Y02W30/00—Technologies for solid waste management
  • Y02W30/50—Reuse, recycling or recovery technologies
  • Y02W30/60—Glass recycling
• • 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
  • Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
  • Y02W30/00—Technologies for solid waste management
  • Y02W30/50—Reuse, recycling or recovery technologies
  • Y02W30/82—Recycling of waste of electrical or electronic equipment [WEEE]

Definitions

• the present invention relates to recovery of valuable elements such as selenium. More specifically, the invention concerns a method, in which at least selenium is separated and/or recycled in the form of selenium dioxide from a compound having the chemical formula Culn x Ga (1 _ X) Se2 , wherein x has a value from 0.01 to 0.99. This allows for recycling in the field of solar cell technology.
• CIS copper indium diselenide
• CGS copper indium gallium diselenide
• Dissolution of the mixture in sulphuric or nitric acid followed by distillation affords selenium dioxide, which is reduced to selenium with the aid of sulphur dioxide. Further, gallium and indium are separated. The method includes a large number of steps.
• Thin Solid Films, 361-362(2000)400-405 discloses that air annealing of CIGS results in gallium diffusion to the top of the layer, where it forms an oxide film of Ga 2 0 3 estimated to be 200 nm in thickness, and that the creation of a Ga 2 0 3 film on the surface can hinder the oxygen transport into the layer.
• It is an object of the invention is to overcome or at least mitigate some of the
• the present invention is based on the insight that Se0 2 , i.e. selenium dioxide, is formed by heating a material comprising a compound of formula (I), i.e. Culn x Ga (1 _ x) Se 2 wherein x has a value from 0.01 to 0.99, while subjecting it to a gas flow comprising oxygen.
• the Se0 2 may be further converted into elemental selenium in high yield and purity by reduction reaction using Riley reaction conditions, with the aid of sulphur dioxide as reducing agent or using any other reducing agent suitable for this purpose known in the art to the skilled person.
• x has a value from 0.01 to 0.99
• said method comprises the steps of:
• the material comprising the compound of formula (I) may be obtained from a solar cell sputtering target.
• the solar cell sputtering target may be crushed so that it is in the form of a powder.
• selenium dioxide and a CIG i.e. a copper indium gallium
• the selenium dioxide and the residue may be collected separately from each other and may, if desired, be subjected to further transformations. Elemental selenium of high purity may be obtained when the Se0 2 is subjected to Riley reaction conditions or reduced with sulphur dioxide.
• Figure 1 shows the selenium content in the remaining CIG residue after oxidation of a material comprising CIGS as a function of the temperature at which the oxidation is performed.
• Figure 2 shows XRD patterns for (a) a material comprising CIGS before oxidation, (b) the CIG residue after oxidation at 800 °C for 24 hours and (c) the CIG residue after oxidation at 1000 °C for 24 hours.
• x has a value from 0.01 to 0.99
• said method comprises the steps of:
• x may be non-integers between 0.01 and 0.99.
• x in the compound of formula (I) is from 0.01 to 0.99, from 0.1 to 0.9, from 0.2 to 0.8 or from 0.3 to 0.7. Alternatively, x may be about 0.95.
• a compound of formula (I) as defined hereinbefore or hereinafter in which x in the compound of formula (I) is from 0.01 to 0.99 is denominated CIGS.
• the material comprising a compound of formula (I) may be obtained from a solar cell sputtering target, possibly a used solar cell sputtering target, the layer deposited on sputtering masks during sputtering, solar cells rejected in the quality control or used solar cells.
• a material is understood to mean one or more materials.
• the solar cell sputtering target may be crushed, for instance with a mortar, to provide a powder.
• a material comprising a compound of formula (I) in the form of a powder is in the form of a powder, in which 60 to 70 wt% has a particle size between 0.25 and 2.0 mm.
• a material comprising a compound of formula (I) in the form of a granulate, flakes or chips is provided.
• the compound of formula (I) may have a selenium content from 30 to 70 wt%. In a further embodiment, the compound of formula (I) may have a selenium content of approximately 50wt%.
• the selenium content in the compound of formula (I) is at least 50 mol%.
• the total content of indium and gallium may be 25-30 mol% and/or the total content of copper may be 20-25 mol%.
• the total content of gallium in the compound of formula (I) may be 1-25 mol% or 5-7 mol%.
• the material comprising the compound of formula (I) is heated to a temperature of at least about 500 °C and is contacted with a gas flow comprising oxygen. This results in oxidation of the material comprising a compound of formula (I).
• the term "contacted” in the context of "contacting the material” is intended to include, but is not limited to, a gas flow above, beneath and/or through the material.
• the material comprising the compound of formula (I) may be heated to a temperature between 500 and 1200 °C.
• the material comprising the compound of formula (I) is heated to 500, 600, 700, 800, 900, 1000, 1100 or 1200 °C.
• the material comprising the compound of formula (I) may be heated to about 800-1200°C, 800-1000°C or 900-1000°C.
• the oxidation of the material comprising a compound of formula (I) may be performed by simultaneous heating and exposure to a gas flow comprising oxygen. Accordingly, in a further embodiment steps a) and b) of the method of the present invention are at least partly overlapping. When steps a) and b) are overlapping they take place simultaneously. It is to be understood that steps a) and b) of the method of the present invention may be performed in any order; i.e. step a) may be performed or started before step b) and vice versa.
• the heating may be turned off after or during step a) or b) in the method as defined hereinbefore or hereinafter. When the heating is turned off the temperature of the material will decrease gradually allowing for oxidation during a certain time. When the temperature of the material is less than about 500 °C very little oxidation will take place.
• the heating of the material comprising the compound of formula (I) may be achieved with the aid of an oven such as tube furnace, fluidized bed furnace or rotating furnace.
• the method of the invention is performed at atmospheric pressure.
• the method of the invention may also be performed at a pressure different from atmospheric pressure.
• the gas flow comprises oxygen.
• the gas flow may be air, pure oxygen gas (0 2 ), ozone (0 3 ) or mixtures thereof.
• step c) following on from step b) and preceding step d) in which:
• x has a value from 0.01 to 0.99
• said method comprises the steps of:
• the material in step c) in the method as defined hereinbefore or hereinafter, is cooled to room temperature.
• room temperature intended to mean 20 to 25 °C at atmospheric pressure.
• the cooling may take place in various ways known to the person skilled in the art.
• the gas flow comprising oxygen may contribute to the cooling of the material.
• the gas flow comprising oxygen may be exchanged for another gas flow comprising cheaper gas or gas mixtures.
• the gas used during step c) may be cooled to a temperature below room temperature.
• water or other coolants may be used to cool the furnace.
• the gas flow may be turned off after or during step b), c) or d) in the method as defined hereinbefore or hereinafter. In one embodiment, the gas flow is turned off after step c) and before step d).
• the sample comprising a compound of formula (I) may be heated while it is contacted with a gas flow comprising oxygen from 6 to 36 hours.
• the method is not limited to this reaction time.
• the method as defined hereinabove or hereinafter allows for collecting the formed Se0 2 and the remaining CIG residue.
• the Se0 2 sublimes by using the method of the present invention and is easy to collect and further transform into elemental selenium in high yield and purity using standard conditions such as Riley reaction conditions or reaction with sulphur dioxide. Typically, the yield is at least 90% and the purity at least 99%.
• the present invention allows for easy removal of selenium in the form of Se0 2 from a material comprising a compound of formula (I) as defined hereinbefore or hereinafter thereby allowing for recycling. This is advantageous in the field of solar cell technology where the purity requirements are very high, and may also be of considerable use in other areas.
• a CIG residue that is obtainable according to the method of the present invention wherein x has a value from 0.01 to 0.99 in the compound of formula (I) used in step a). While not wishing to be bound by any specific theory it is believed that the CIG residue comprises oxides of copper, indium and gallium.
• the CIG residue has a low selenium content.
• the selenium content of the CIG residue may be equal to or less than 6 wt%.
• the CIG residue has a selenium content of 0 to 10 wt%.
• the CIG residue has a selenium content of 0 to 5 wt%.
• Yet an embodiment of the present of the invention is to provide a CIG residue having a selenium content of 0 to 1 wt%.
• the selenium content in one of the layers may be as low as about 0.3 wt% whereas the other layer has a selenium content of about 5 wt%.
• the layers may be separated and collected.
• Still an embodiment of the invention is a method as defined hereinbefore or hereinafter in which the material comprising the compound of formula (I) is stirred or mixed during steps a) and/or b) thereby providing a CIG residue having only one layer that is lacking selenium or has a uniform and low content of selenium.
• low content is meant a selenium content between 0 and 10 wt%.
• the stirring may be achieved by mechanical means.
• the mixing may be achieved by using a fluidized bed.
• FIG. 1 shows oxidation of a material comprising CIGS in the form of a powder and having a selenium content of approximately 50 wt% when it is subjected to an oxygen gas flow of 200 ml/min during 24 hours at various temperatures and at atmospheric pressure.
• the selenium content of the resulting CIG material is shown in wt% of the amount of selenium in the material comprising CIGS as a function of the temperature at which the experiment was performed. Experiments were performed at 500, 600, 700, 800 and 1000 °C.
• the selenium content in the CIG residue varied as follows in wt% of the original amount of selenium in the CIGS material:
• the selenium content in the CIG residue is approximately 50 wt% of the values above.
• the experiment performed at 800°C resulted in a CIG residue having a selenium content of approximately 25 wt%.
• the experiment performed at 1000°C resulted in a CIG residue having a selenium content of approximately 2 wt%.
• Figure 2 shows X ray powder diffraction patterns for a material comprising CIGS in the form of a powder and having a selenium content of approximately 50wt% before and after subjecting the material to an oxygen gas flow of 200 ml/min during 24 hours at 800 °C and 1000 °C at atmospheric pressure, respectively.
• the XRD pattern is shown for the material comprising CIGS before oxidation.
• the XRD pattern is shown for the CIG material after oxidation at 800 °C.
• the XRD pattern is shown for the CIG material after oxidation at 1000 °C.
• the peaks have been denominated 1 , 2, 3, 4, 5 and 6.
• the peaks are attributed to the following materials: 1 : CIGS; 2: ln 2 0 3 ; 3: CuO; 4: Cu 2 ln 2 0 5 ; 5: Ga 2 0 3 ; and 6: CuGaln0 4 .
• the CIG residue comprises oxides of copper, indium and gallium.
• a sample comprising CIGS provided by Midsummer AB was used as a starting material.
• the sample was crushed in a marble mortar to a powder and this material was used as a starting material for all the oxidation experiments.
• the particle size of the powder was determined by sieving. 5.5 g of starting material was sieved through a mesh 10 sieve followed by mesh 60 and finally a mesh 200 (ASTM E-1 1 , W.S Tyler inc.). The material passing each sieve was weighed to give the particle size distribution.
• 13.5 g of the starting material was placed in a furnace boat and the container was placed in the middle of a quartz tube in a tube furnace.
• the temperature in the furnace was regulated with a thermocouple on the outside of the quarts tube.
• An oxygen cylinder (99%, AGA) was connected to one end of the quartz tube through plastic tubing and a flow meter.
• the gas flow through the furnace was adjusted to 200 ml/min.
• the other end of the quartz tube was connected to a cooler in order to trap the selenium dioxide that did not sublime in the quartz tube directly outside the furnace.
• the cooler was cooled with water at 20 °C and the discharge gas was bubbled through ultrapure water to collect the last of the selenium dioxide.
• Standard solutions containing 0.5 pg/ml, 1 pg/ml, 10 pg/ml and 40 pg/ml cupper, indium, gallium and selenium was prepared by dilution of ICP-OES standard solutions (l OOOMg/ml, Ultra Scientific). All samples and standards was diluted with a solution of 0.1 M nitric acid made from suprapure nitric acid (65%, Merck) and ultrapure water obtained from a Milli-Q system (>18 ⁇ , Millipore Milli-Q Plus 185).
• the purity of the recycled selenium with respect to chromium, manganese, iron, nickel, copper, zinc, gallium and indium was determined by using a combination of ICP-MS (Perkin Elmer, ELAN 6000) and ICP-OES (Thermo Scientific iCAP 6500).
• a solution containing 1000 pg/ml selenium was prepared by dissolution of 1 g of selenium in 69,3 ml suprapure nitric acid (65%, Merck) followed by dilution up to 1000 ml with ultrapure water.
• ICP-MS standards (lO g/ml, High-Purity Standards) were used to prepare a solution containing 10 ng/ml of all the analysed elements.
• the exact concentration of selenium in the selenium solution was determined with ICP- OES.
• the solution was diluted with 1 M suprapure nitric acid and standard solutions containing 0.5 pg/ml, 1 ⁇ g/ml, 10 ⁇ g/ml and 40 ⁇ g/ml selenium was prepared by dilution of ICP-OES standard solutions (1000pg/ml, Ultra Scientific).
• the organic product from the Riley oxidation was dissolved and diluted to a concentration of 16 mg/l in acetone (pro analysis, Fischer Scientific) and analysed with GC-MS (Hewlet Packard, GI800A GCD System) using a sp2330 column.
• GC-MS Hewlet Packard, GI800A GCD System
• NAA neutron activation analysis
• the ampoules were sealed and sent to the reactor, where the samples were irradiated for a total of 123 hours and 23 minutes. After the irradiation the samples were analysed with high purity germanium detectors (HPGe, Canberra ⁇ -analyst, ORTEC and Tennelec, respectively). The 1099 and 1291 keV gamma lines of 59 Fe were used in the
• Table 1 The result of the examination of the particle distribution of the starting material can be seen in Table 1.
• Table 1 the particle distribution of the starting material given as the percentage of weight of the material passing through a certain mesh compared with the weight of the starting material. Table 1.
• Table 3 The composition of the top and bottom layers of the residue after oxidation at 1000°C.
• the reaction was first performed at room temperature and resulted in red selenium that was difficult to collect due to the fine particle size and surface activity of the red selenium. However, upon heating to 80°C the red selenium was observed to gradually transform into grey selenium. The grey selenium is not surface active and forms larger particles which makes it more easily collected. An additional advantage of this transformation is that the formation of new red selenium can be distinguished. The time needed for complete reduction can thereby be easily determined. It was concluded that 15 minutes was sufficient time for complete reaction.
• the purity of selenium from both reduction experiments were analysed along with the purity of the selenium dioxide from the oxidation test at 1000°C, the same selenium dioxide that was used in the reduction experiments.
• the selenium dioxide was analysed to see possible differences in the purity before and after the reduction. Also, the difference in purity depending on the reduction method used was of interest.
• the results from the ICP-MS measurements were analysed and the concentrations of the different impurities in the selenium were calculated, see Table 4.
• Chromium, manganese, iron, nickel and zinc were analyzed since they pose a problem in the solar cell production by decreasing the efficiency of the solar cells.
• the concentration of chromium, manganese, nickel and zinc in the selenium was determined to be below 1 ppm for each element.
• the iron concentration was between 4 and 10 ppm for all selenium materials. Copper, indium and gallium are not viewed as a problem, but they were analyzed since it was of interest to know if there were any residues in the selenium.
• the concentration of these elements was determined to be below 15ppm in all cases.
• the uncertainty corresponds to one standard deviation.
• a comparison between the two different reduction methods gave that the Riley reaction gave a somewhat lower purity.

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• 2012
  • 2012-12-14 US US14/364,454 patent/US20140341799A1/en not_active Abandoned
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