EP0089184A1 - Process for the recovery of silver from metallurgical intermediates - Google Patents
Process for the recovery of silver from metallurgical intermediates Download PDFInfo
- Publication number
- EP0089184A1 EP0089184A1 EP83301318A EP83301318A EP0089184A1 EP 0089184 A1 EP0089184 A1 EP 0089184A1 EP 83301318 A EP83301318 A EP 83301318A EP 83301318 A EP83301318 A EP 83301318A EP 0089184 A1 EP0089184 A1 EP 0089184A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- silver
- solution
- thiosulphate
- leach
- residue
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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- 229910052709 silver Inorganic materials 0.000 title claims abstract description 60
- 239000004332 silver Substances 0.000 title claims abstract description 58
- 238000000034 method Methods 0.000 title claims description 14
- 239000000543 intermediate Substances 0.000 title description 9
- 238000011084 recovery Methods 0.000 title description 5
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 claims abstract description 57
- DHCDFWKWKRSZHF-UHFFFAOYSA-L thiosulfate(2-) Chemical compound [O-]S([S-])(=O)=O DHCDFWKWKRSZHF-UHFFFAOYSA-L 0.000 claims abstract description 32
- 229910052751 metal Inorganic materials 0.000 claims abstract description 18
- 239000002184 metal Substances 0.000 claims abstract description 18
- 239000010931 gold Substances 0.000 claims abstract description 14
- 239000002002 slurry Substances 0.000 claims abstract description 14
- 229910052737 gold Inorganic materials 0.000 claims abstract description 10
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 claims abstract description 8
- -1 platinum group metals Chemical class 0.000 claims abstract description 6
- 239000010970 precious metal Substances 0.000 claims description 16
- 239000000463 material Substances 0.000 claims description 12
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 9
- 239000003638 chemical reducing agent Substances 0.000 claims description 2
- 239000012141 concentrate Substances 0.000 claims description 2
- 239000000243 solution Substances 0.000 description 27
- 239000011133 lead Substances 0.000 description 22
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 description 14
- 239000000460 chlorine Substances 0.000 description 14
- 229910052801 chlorine Inorganic materials 0.000 description 14
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 12
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical group [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 12
- 239000007787 solid Substances 0.000 description 9
- 238000000605 extraction Methods 0.000 description 7
- 150000002739 metals Chemical class 0.000 description 7
- 239000002244 precipitate Substances 0.000 description 7
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 6
- KDLHZDBZIXYQEI-UHFFFAOYSA-N palladium Substances [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 description 6
- 239000011669 selenium Substances 0.000 description 6
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 5
- BUGBHKTXTAQXES-UHFFFAOYSA-N Selenium Chemical compound [Se] BUGBHKTXTAQXES-UHFFFAOYSA-N 0.000 description 5
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 5
- 238000002386 leaching Methods 0.000 description 5
- 239000000203 mixture Substances 0.000 description 5
- 229910052711 selenium Inorganic materials 0.000 description 5
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 4
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 4
- 239000004568 cement Substances 0.000 description 4
- 238000005660 chlorination reaction Methods 0.000 description 4
- 239000010949 copper Substances 0.000 description 4
- 230000003247 decreasing effect Effects 0.000 description 4
- 239000001117 sulphuric acid Substances 0.000 description 4
- 235000011149 sulphuric acid Nutrition 0.000 description 4
- 229910052714 tellurium Inorganic materials 0.000 description 4
- PORWMNRCUJJQNO-UHFFFAOYSA-N tellurium atom Chemical compound [Te] PORWMNRCUJJQNO-UHFFFAOYSA-N 0.000 description 4
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 3
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 3
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 description 3
- 229910052785 arsenic Inorganic materials 0.000 description 3
- RQNWIZPPADIBDY-UHFFFAOYSA-N arsenic atom Chemical compound [As] RQNWIZPPADIBDY-UHFFFAOYSA-N 0.000 description 3
- 229910052802 copper Inorganic materials 0.000 description 3
- 238000004090 dissolution Methods 0.000 description 3
- 239000000706 filtrate Substances 0.000 description 3
- 238000001914 filtration Methods 0.000 description 3
- 239000011777 magnesium Substances 0.000 description 3
- 239000011734 sodium Substances 0.000 description 3
- 229910052725 zinc Inorganic materials 0.000 description 3
- 239000011701 zinc Substances 0.000 description 3
- RFSUNEUAIZKAJO-ARQDHWQXSA-N Fructose Chemical compound OC[C@H]1O[C@](O)(CO)[C@@H](O)[C@@H]1O RFSUNEUAIZKAJO-ARQDHWQXSA-N 0.000 description 2
- WQZGKKKJIJFFOK-GASJEMHNSA-N Glucose Natural products OC[C@H]1OC(O)[C@H](O)[C@@H](O)[C@@H]1O WQZGKKKJIJFFOK-GASJEMHNSA-N 0.000 description 2
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 2
- 239000005864 Sulphur Substances 0.000 description 2
- 229910021529 ammonia Inorganic materials 0.000 description 2
- 239000010953 base metal Substances 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000013067 intermediate product Substances 0.000 description 2
- 229910052742 iron Inorganic materials 0.000 description 2
- 229910052745 lead Inorganic materials 0.000 description 2
- 229910052759 nickel Inorganic materials 0.000 description 2
- 229910052763 palladium Inorganic materials 0.000 description 2
- 229910052697 platinum Inorganic materials 0.000 description 2
- 238000000926 separation method Methods 0.000 description 2
- GEHJYWRUCIMESM-UHFFFAOYSA-L sodium sulfite Chemical compound [Na+].[Na+].[O-]S([O-])=O GEHJYWRUCIMESM-UHFFFAOYSA-L 0.000 description 2
- GUBGYTABKSRVRQ-XLOQQCSPSA-N Alpha-Lactose Chemical compound O[C@@H]1[C@@H](O)[C@@H](O)[C@@H](CO)O[C@H]1O[C@@H]1[C@@H](CO)O[C@H](O)[C@H](O)[C@H]1O GUBGYTABKSRVRQ-XLOQQCSPSA-N 0.000 description 1
- JPVYNHNXODAKFH-UHFFFAOYSA-N Cu2+ Chemical compound [Cu+2] JPVYNHNXODAKFH-UHFFFAOYSA-N 0.000 description 1
- RFSUNEUAIZKAJO-VRPWFDPXSA-N D-Fructose Natural products OC[C@H]1OC(O)(CO)[C@@H](O)[C@@H]1O RFSUNEUAIZKAJO-VRPWFDPXSA-N 0.000 description 1
- 229930091371 Fructose Natural products 0.000 description 1
- 239000005715 Fructose Substances 0.000 description 1
- GUBGYTABKSRVRQ-QKKXKWKRSA-N Lactose Natural products OC[C@H]1O[C@@H](O[C@H]2[C@H](O)[C@@H](O)C(O)O[C@@H]2CO)[C@H](O)[C@@H](O)[C@H]1O GUBGYTABKSRVRQ-QKKXKWKRSA-N 0.000 description 1
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 1
- 229910021607 Silver chloride Inorganic materials 0.000 description 1
- 238000003723 Smelting Methods 0.000 description 1
- 239000004133 Sodium thiosulphate Substances 0.000 description 1
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 description 1
- LKDRXBCSQODPBY-ZXXMMSQZSA-N alpha-D-fructopyranose Chemical compound OC[C@]1(O)OC[C@@H](O)[C@@H](O)[C@@H]1O LKDRXBCSQODPBY-ZXXMMSQZSA-N 0.000 description 1
- XYXNTHIYBIDHGM-UHFFFAOYSA-N ammonium thiosulfate Chemical compound [NH4+].[NH4+].[O-]S([O-])(=O)=S XYXNTHIYBIDHGM-UHFFFAOYSA-N 0.000 description 1
- 229910052787 antimony Inorganic materials 0.000 description 1
- WATWJIUSRGPENY-UHFFFAOYSA-N antimony atom Chemical compound [Sb] WATWJIUSRGPENY-UHFFFAOYSA-N 0.000 description 1
- WQZGKKKJIJFFOK-VFUOTHLCSA-N beta-D-glucose Chemical compound OC[C@H]1O[C@@H](O)[C@H](O)[C@@H](O)[C@@H]1O WQZGKKKJIJFFOK-VFUOTHLCSA-N 0.000 description 1
- 229910052797 bismuth Inorganic materials 0.000 description 1
- JCXGWMGPZLAOME-UHFFFAOYSA-N bismuth atom Chemical compound [Bi] JCXGWMGPZLAOME-UHFFFAOYSA-N 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 150000001805 chlorine compounds Chemical class 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 239000000470 constituent Substances 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 239000008121 dextrose Substances 0.000 description 1
- 238000006073 displacement reaction Methods 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 239000008187 granular material Substances 0.000 description 1
- 229910001385 heavy metal Inorganic materials 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 239000004615 ingredient Substances 0.000 description 1
- 239000008101 lactose Substances 0.000 description 1
- 229910052749 magnesium Inorganic materials 0.000 description 1
- 238000013021 overheating Methods 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- HKZLPVFGJNLROG-UHFFFAOYSA-M silver monochloride Chemical compound [Cl-].[Ag+] HKZLPVFGJNLROG-UHFFFAOYSA-M 0.000 description 1
- 239000010802 sludge Substances 0.000 description 1
- 235000010265 sodium sulphite Nutrition 0.000 description 1
- AKHNMLFCWUSKQB-UHFFFAOYSA-L sodium thiosulfate Chemical compound [Na+].[Na+].[O-]S([O-])(=O)=S AKHNMLFCWUSKQB-UHFFFAOYSA-L 0.000 description 1
- 235000019345 sodium thiosulphate Nutrition 0.000 description 1
- LSNNMFCWUKXFEE-UHFFFAOYSA-L sulfite Chemical compound [O-]S([O-])=O LSNNMFCWUKXFEE-UHFFFAOYSA-L 0.000 description 1
- 239000010414 supernatant solution Substances 0.000 description 1
- 229910052718 tin Inorganic materials 0.000 description 1
- 229910000859 α-Fe Inorganic materials 0.000 description 1
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
- C22B11/00—Obtaining noble metals
- C22B11/06—Chloridising
Definitions
- This invention relates to the recovery of silver from metallurgical intermediate materials which also contain one or more other precious metals.
- base metal ores such as those of copper, nickel, zinc, and lead also contain metals of the platinum group together with silver, gold, selenium, tellurium and other constituents. Such ores form important sources of the valuable metals which are known colloquially as "precious metals", that is to say the six platinum group metals, gold and silver.
- metals occur in the various metal ores in small amounts and become concentrated during the working up of the base metals in the form of various metallurgical intermediates, including anode sludges, leach residues and cements.
- the compositionsof these precious metal-containing materials thus vary widely depending upon the nature of the ore. Despite the differences in composition these materials tend to lend themselves to a more or less common scheme of treatment and tend to contain largely the same ingredients, although the proportions of valuable metals therein can vary.
- metals which may be present in the precious metals intermediate products include all six members of the platinum group, gold, silver, selenium, tellurium, lead, arsenic, antimony, tin, bismuth, copper, nickel, zinc, iron and sulphur.
- One known method can involve decopperizing of the precious metal intermediate by leaching with sulphuric acid and then smelting in a Dor6 furnace in which silver may be recovered in the form of DorG metal. Such a procedure is expensive and can produce harmful emissions of selenium, arsenic, lead and other heavy metals.
- the present method provides a hydrometallurgical method for working up precious-metal-containing intermediate materials to give selective and efficient separation of silver therefrom.
- silver present in a metallurgical intermediate material that also contains one or more other precious metals is concentrated and recovered by slurrying the material with water, chlorinating the aqueous slurry to dissolve platinum group metals and gold present and to produce a residue enriched in silver, dissolving silver from the residue with an aqueous thiosulphate solution and recovering silver from the resulting solution.
- the silver-containing precious metal intermediates to be treated should be slurried with water in the proportion of from 5 to 50% by weight solids.
- the resulting slurry is then chlorinated for a time sufficient to convert the silver content to silver chloride and to chlorinate most of the remaining metal values as chlorides.
- hydrochloric acid can be formed by reactions between chlorine and elements such as sulphur, selenium, tellurium, and arsenic or compounds thereof.
- a convenient temperature range for chlorination is from 60 to 80°C. Since chlorination is usually exothermic, cooling of the solution may sometimes be required, and the rate of addition of chlorine should be controlled to avoid possible overheating and/or excessive chlorine consumption.
- the silver-containing residue can then be leached, preferably at ambient temperature, with an aqueous thiosulphate solution, e.g. sodium thiosulphate, to dissolve silver selectively with regard to impurities such as silica and ferrites which may also be present in the silver-containing residue.
- an aqueous thiosulphate solution e.g. sodium thiosulphate
- the thiosulphate leach may be conducted at a temperature of from 10 to 80°C.
- Thiosulphate should be used in approximately the proportions of two to four mols of thiosulphate for each mol of silver to be leached.
- The'pH of the thiosulphate solution should be at least 2,and when lead is present in the chlorine leach residue to an extent requiring selective removal of the silver, the pH of the thiosulphate leach solution should be at least 7 and more preferably ⁇ pH 9 or pH 10.
- the thiosulphate leach is highly selective for silver as compared with lead in the precipitate being dissolved.
- a further advantage of maintaining the thiosulphate solution basic is that the stability of the solution is thereby increased. Small amounts of sulphite, e.g. sodium sulphite, added to the thiosulphate leach solution will also improve its stability.
- the thiosulphate leach solution containing silver from the residue may be treated in a variety of ways to recover the silver.
- cementation with metals such as iron, zinc or magnesium at ambient temperature produces cements analyzing about 90% silver.
- Organic reducing agents e.g. fructose, dextrose and lactose, can be used to produce silver precipitates of high purity, e.g. containing at least 90% of silver.
- Electrolytic recovery means may also be used.
- the composition of the silver-containing precious metal intermediates to be treated in accordance with the invention can vary widely depending upon the ore from which they are obtained, and it may be convenient to subject them to preliminary treatment.
- the sludge may be given a decopperizing leach in sulphuric acid prior to treatment in accordance to the invention.
- a lead removal step may be employed prior to treatment of the intermediate in accordance with the invention.
- the chlorine leach residue was then leached with thiosulphate as follows: 33.8 litres of water was added to 15.5 kg of the above chlorine leach residue, which already contained 39% moisture. NaOH was added to the agitated slurry to bring the pH to 10.0 at 22°C. Then 3.75 kg of Na 2 S 2 0 3 was added (3.9 kg Na 2 S 2 0 3 /kg Ag) and the slurry was agitated for 30 minutes at a pH of 10 (22°C). The residue was filtered off and washed with one cake displacement of water.
- the leach residue contained a large quantity of filter-aid, which tends to trap large amounts of leach liquor
- the wet residue was subjected to a repulp leach using 11 litres of water and 0.4 kg of Na 2 S 2 0 3 .
- Leaching was again conducted for 30 minutes at 22°C (pH 10).
- the leach residue was separated from the solution by filtration.
- the leach , residue analyzed 0.11% Ag and 5.2% Pb. 99.1% of the silver was extracted with only 0.8% of the lead.
- This example shows the effect of varying the chlorine leaching conditions.
- This example shows the effect of acidity on the extraction of silver by a thiosulphate solution.
- the leach conditions were similar to Example 1 and are listed in Table 2, together with the results of duplicate tests.
- the extraction of silver was lowest ( ⁇ 97%) at a pH of 2.0, and was generally 99% or higher between pH 4 and 12.
- the dissolution of lead was strongly influenced by the pH. At pH 6 and below, more than 75% of the Pb was dissolved, whereas at pH 8 less than 20% Pb was extracted and at a pH of 10 the dissolution of Pb was only ⁇ 1%.
- compositions of five other precious metal-containing materials susceptible to treatment in accordance with the invention are shown in Table 3. Each of these materials was chlorine leached under the conditions and for the times shown in Table 4. It will be seen from Table 4 that excellent extractions of platinum-group metals and gold were achieved with all the materials treated although the compositions thereof varied widely. On the other hand, extractions of silver were low.
- the compositions, in weight per cent, of the chlorine leach residues are shown in Table 5. All of the chlorine leach residues were susceptible to thiosulphate leaching, in accordance with the invention, to dissolve silver.
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- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Manufacturing & Machinery (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Manufacture And Refinement Of Metals (AREA)
Abstract
An aqueous slurry of the silver-containing intermediate is chlorinated to dissolve platinum group metals and gold leaving the silver in the residue, from which it is dissolved with an aqueous thiosulphate solution. When the intermediate contains lead, the thiosulphate leach solution should have a pH of at least 7. Silver is recovered from the final solution by cementation or reduction.
Description
- . This invention relates to the recovery of silver from metallurgical intermediate materials which also contain one or more other precious metals.
- Many base metal ores, such as those of copper, nickel, zinc, and lead also contain metals of the platinum group together with silver, gold, selenium, tellurium and other constituents. Such ores form important sources of the valuable metals which are known colloquially as "precious metals", that is to say the six platinum group metals, gold and silver.
- These metals occur in the various metal ores in small amounts and become concentrated during the working up of the base metals in the form of various metallurgical intermediates, including anode sludges, leach residues and cements. The compositionsof these precious metal-containing materials thus vary widely depending upon the nature of the ore. Despite the differences in composition these materials tend to lend themselves to a more or less common scheme of treatment and tend to contain largely the same ingredients, although the proportions of valuable metals therein can vary. -Thus, metals which may be present in the precious metals intermediate products include all six members of the platinum group, gold, silver, selenium, tellurium, lead, arsenic, antimony, tin, bismuth, copper, nickel, zinc, iron and sulphur. Once the materials are concentrated,e.g. in the form of anode sludges or leach residues, it then becomes important to recover the metal values as completely as possible and to produce metal concentrates of respectable purity. One known method, for example, can involve decopperizing of the precious metal intermediate by leaching with sulphuric acid and then smelting in a Dor6 furnace in which silver may be recovered in the form of DorG metal. Such a procedure is expensive and can produce harmful emissions of selenium, arsenic, lead and other heavy metals.
- It is known also to recover precious metal from intermediate products by dissolution in hydrochloric acid with chlorination followed by ammonia extraction of silver from the resulting residues and recovery of platinum group metals, selenium, and tellurium from the leach liquor. It is also known from the photographic art that thiosulphate solutions can be employed to dissolve silver from light-unaffected portions of film which is employed for photographic purposes. Ammonium thiosulphate leaching of gold and silver from ammoniacal leach residues in the presence of cupric ion and free ammonia is also known.
- Publications relevant to this subject matter include Tsvetnye Metallv, 1963, Vol.36, No.11, pages 85-86; the U.S. Patents Nos. 3,658,510; 4,070,182; 4,269,622 and 4,229,270.
- The present method provides a hydrometallurgical method for working up precious-metal-containing intermediate materials to give selective and efficient separation of silver therefrom.
- According to the invention, silver present in a metallurgical intermediate material that also contains one or more other precious metals is concentrated and recovered by slurrying the material with water, chlorinating the aqueous slurry to dissolve platinum group metals and gold present and to produce a residue enriched in silver, dissolving silver from the residue with an aqueous thiosulphate solution and recovering silver from the resulting solution.
- In carrying out the process, the silver-containing precious metal intermediates to be treated should be slurried with water in the proportion of from 5 to 50% by weight solids. The resulting slurry is then chlorinated for a time sufficient to convert the silver content to silver chloride and to chlorinate most of the remaining metal values as chlorides. In the course of the chlorination a substantial quantity of hydrochloric acid can be formed by reactions between chlorine and elements such as sulphur, selenium, tellurium, and arsenic or compounds thereof. A convenient temperature range for chlorination is from 60 to 80°C. Since chlorination is usually exothermic, cooling of the solution may sometimes be required, and the rate of addition of chlorine should be controlled to avoid possible overheating and/or excessive chlorine consumption.
- After completion of the chlorine leach, the silver-containing residue is separated from the supernatant solution, which now contains the other precious metals.
- The silver-containing residue can then be leached, preferably at ambient temperature, with an aqueous thiosulphate solution, e.g. sodium thiosulphate, to dissolve silver selectively with regard to impurities such as silica and ferrites which may also be present in the silver-containing residue. The thiosulphate leach may be conducted at a temperature of from 10 to 80°C.
- Thiosulphate should be used in approximately the proportions of two to four mols of thiosulphate for each mol of silver to be leached.
- The'pH of the thiosulphate solution should be at least 2,and when lead is present in the chlorine leach residue to an extent requiring selective removal of the silver, the pH of the thiosulphate leach solution should be at least 7 and more preferably ≥ pH 9 or pH 10. When the thiosulphate solution is sufficiently basic, the thiosulphate leach is highly selective for silver as compared with lead in the precipitate being dissolved. A further advantage of maintaining the thiosulphate solution basic is that the stability of the solution is thereby increased. Small amounts of sulphite, e.g. sodium sulphite, added to the thiosulphate leach solution will also improve its stability.
- The thiosulphate leach solution containing silver from the residue may be treated in a variety of ways to recover the silver. For example, cementation with metals such as iron, zinc or magnesium at ambient temperature produces cements analyzing about 90% silver. Organic reducing agents, e.g. fructose, dextrose and lactose, can be used to produce silver precipitates of high purity, e.g. containing at least 90% of silver. Electrolytic recovery means may also be used.
- As noted hereinbefore, the composition of the silver-containing precious metal intermediates to be treated in accordance with the invention can vary widely depending upon the ore from which they are obtained, and it may be convenient to subject them to preliminary treatment. For example, in working up copper refinery sludges to recover silver the sludge may be given a decopperizing leach in sulphuric acid prior to treatment in accordance to the invention. Similarly, a lead removal step may be employed prior to treatment of the intermediate in accordance with the invention.
- Some examples will now be given.
- 66.2 kg of a precious metals-containing feed, analyzing (in per cent by weight) Pt 1.5, Pd 1.6, Au 0.40, Rh 0.16, Ru 0.09, Ag 7.6, Pb 7.1, Se 5.6, Te 0.67, Cu 0.34 was slurried in water at a solids density of n450 g solids per litre of slurry and heated to 60°C. Gaseous chlorine was sparged into the agitated slurry for a total of 4 h at a flowrate of 100 litres/min. After filtration of the leached slurry about 46.5 kg of leach residue was obtained, which was found to an analyze Pt 0.035, Pd 0.016, Au 0.005, Ag 10.1, Pb 3.2%. The following metal extractions were obtained (%): Pt 98, Pd 99.3, Au 99.1, Ag <1.
- The chlorine leach residue was then leached with thiosulphate as follows: 33.8 litres of water was added to 15.5 kg of the above chlorine leach residue, which already contained 39% moisture. NaOH was added to the agitated slurry to bring the pH to 10.0 at 22°C. Then 3.75 kg of Na2S203 was added (3.9 kg Na2S203/kg Ag) and the slurry was agitated for 30 minutes at a pH of 10 (22°C). The residue was filtered off and washed with one cake displacement of water. Since the leach residue contained a large quantity of filter-aid, which tends to trap large amounts of leach liquor, the wet residue was subjected to a repulp leach using 11 litres of water and 0.4 kg of Na2S203. Leaching was again conducted for 30 minutes at 22°C (pH 10). Finally, the leach residue was separated from the solution by filtration. The leach , residue analyzed 0.11% Ag and 5.2% Pb. 99.1% of the silver was extracted with only 0.8% of the lead.
- The thiosulphate leach liquor and the repulp leach liquorwere combined, resulting in a solution analyzing (g/1) Ag 18.0 and Pb 0.07. Sulphuric acid was added to the solution to reach a pH of 4.0 at 22°C. Thcniron powder was added to cement the contained silver values. The pH was held at 4 by simultaneous addition of sulphuric acid. When a redox potential of -400 mV(SCE) was reached, the slurry was filtered. The silver cement analyzed (%) Ag 87.1, Fe 9.3, Pb 0.38, S 1.4. More than 99.9% of the silver had been cemented and the barren solution analyzed 10 mg/l Ag.
- This example shows the effect of varying the chlorine leaching conditions.
- 170 g of a moist (39.4% H20) precious metals containing feed analyzing (%) Pt 1.73, Pd 1.65, Au 0.33, Ag 2.00, Pb 3.43 and Si02 52.0 was slurried with water alone and with various amounts of hydrochloric acid, as shown in Table 1. The resulting slurries (30-35% solids) were agitated and heated to 80°C. Gaseous chlorine was bubbled into the slurry at a flowrate of ~1 g/1 slurry/min. for a total of 4 h. The slurry was then filtered and the leach residue and the leach liquor were analyzed.
- As shown in Table 1, it was found that the extraction of the precious metals Pt, Pd and Au was essentially unaffected by the initial acidity. However, much less silver was extracted (only 0.2%) in the test where the feed was slurried with water. Thus, a better separation of silver from Pt, Pd and Au was achieved.
- This example shows the effect of acidity on the extraction of silver by a thiosulphate solution.
- A chlorine leach residue analyzing, in weight per cent, Ag 17.3 and Pb 9.9, was subjected to thiosulphate leach tests at various pH values between 2 and 12.
The leach conditions were similar to Example 1 and are listed in Table 2, together with the results of duplicate tests. The extraction of silver was lowest (~97%) at a pH of 2.0, and was generally 99% or higher between pH 4 and 12. The dissolution of lead was strongly influenced by the pH. At pH 6 and below, more than 75% of the Pb was dissolved, whereas at pH 8 less than 20% Pb was extracted and at a pH of 10 the dissolution of Pb was only ~1%. - The next four Examples (Nos. 4-7) illustrate the recovery of silver from thiosulphate leach solutions obtained in the process of the invention.
- A thiosulphate leach liquor (1.0 litres) analyzing (g/1) Ag 18.4 and S203= 68 at pH 10 was acidified to pH 4, and 3.8 g of Mg granules (0.177-0.21mm) was added over 2 h with simultaneous addition of 151.5 ml of 50 g/l H2SO4 solution to maintain pH 4. During this period the temperature rose from 22 to 31°C and the redox potential of the solution decreased from +70 mV to -250 mV (Pt vs SCE). After filtration and drying, the solids (20.14.g) analyzed (%): Ag 90.9, Mg 1.6 and S 3.15. The filtrate (1.085 litres) contained 0.042 g/1 Ag. Thus, 99.7% of the silver was recovered in the solids.
- A thiosulphate leach liquor (1.0 litres) analyzing (g/1) Ag 18.5, Pb 0.11 and S203 = 69 at pH 10 was heated at 80°C and 14.3 g of D-fructose was added. The solution was maintained at pH 10 by addition of 72.9 ml of a 150 g/1 NaOH solution. After 15 minutes the redox potential of the solution had decreased from 0 mV to -660 mV (Pt vs SCE) and the silver mirror, originally plated on the sides of the beaker, disappeared leaving a flocculant precipitate (18.23 g) which analyzed (%): Ag 97.5, Pb 0.55, and S 0.66. The filtrate (1.044 litres) analyzed <5 mg/l Ag. Thus, 99.97% of the silver was recovered in the solids.
- A thiosulphate leach liquor (1.0 litres) analyzing (g/1) Ag 17.9, Pb 0.10, and S2O3= 67 at pH 10 was heated to 80°C and 14.3 g of D-glucose was added. The solution was maintained at pH 10 by addition of 265 ml of a 38 g/1 NaOH solution. After 30 minutes the redox potential of the solution had decreased from +30 mV to -660 mV (Pt vs SCE) and the silver mirror, originally plated on the sides of the beaker, disappeared leaving a flocculant precipitate (17.45 g) which analyzed (%): Ag 97.9, Pb 0.52, and S 0.56. The filtrate (1.26 litres) contained 40 mg/l Ag. Thus, 99.7% of the silver was recovered in the solids.
- A thiosulphate leach liquor (1.0 litres) containing 17.9 g/1 Ag and 67 g/1 S2O3= was adjusted to pH 13 at 24°C by adding 16 g NaOH. Then 14.3 g of D=fructose was added. After 2 hours the redox potential had decreased from +60 mV to -225 mV (Pt vs SCE) and 8.85 g of precipitate was filtered off. After standing overnight, an additional 8.30 g of precipitate was recovered. The combined precipitates analyzed 99.6% Ag while the solution contained only 70 mg/l Ag. Thus, 99.6% of the silver was recovered in the solids.
- The compositions of five other precious metal-containing materials susceptible to treatment in accordance with the invention are shown in Table 3. Each of these materials was chlorine leached under the conditions and for the times shown in Table 4. It will be seen from Table 4 that excellent extractions of platinum-group metals and gold were achieved with all the materials treated although the compositions thereof varied widely. On the other hand, extractions of silver were low. The compositions, in weight per cent, of the chlorine leach residues are shown in Table 5. All of the chlorine leach residues were susceptible to thiosulphate leaching, in accordance with the invention, to dissolve silver.
Claims (7)
1. A hydrometallurgical method for treating a metallurgical intermediate material that contains silver and also one or more other precious metals to concentrate and recover silver therefrom, characterised by the steps of slurrying the material with water, chlorinating the aqueous slurry to dissolve platinum group metals and gold and produce a residue enriched in silver, dissolving silver from the residue with an aqueous thiosulphate solution, and recovering silver from the resulting solution.
2. A process according to claim 1, characterised in that the thiosulphate solution has a pH of at least-2.
3. A process according to claim 2, characterised in that the silver-enriched residue also contains lead and the thiosulphate solution has a pH of at least 7.
4. A process according to claim 3, characterised in that the thiosulphate solution has a pH of at least 9.
5. A process according to any preceding claim, characterised in that the thiosulphate leach is conducted at ambient temperature.
6. A process according to any preceding claim, characterised in that the silver is recovered from the final solution by cementation.
7. A process according to any preceding claim, characterised in that the silver is recovered from the final solution by reduction with an organic reducing agent.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000398157A CA1188522A (en) | 1982-03-11 | 1982-03-11 | Recovery of silver from precious metal-containing intermediates |
| CA398157 | 1982-03-11 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| EP0089184A1 true EP0089184A1 (en) | 1983-09-21 |
Family
ID=4122276
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| EP83301318A Withdrawn EP0089184A1 (en) | 1982-03-11 | 1983-03-10 | Process for the recovery of silver from metallurgical intermediates |
Country Status (2)
| Country | Link |
|---|---|
| EP (1) | EP0089184A1 (en) |
| CA (1) | CA1188522A (en) |
Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0176100A1 (en) * | 1984-09-26 | 1986-04-02 | Austria Metall Aktiengesellschaft | Hydrometallurgical process for treating electrolytic copper refinery anode slimes |
| EP0212453A1 (en) * | 1985-08-07 | 1987-03-04 | Noranda Inc. | Process for the recovery of gold from a precious metal bearing sludge concentrate |
| US4666514A (en) * | 1985-01-25 | 1987-05-19 | Austria Metall Aktiengesellschaft | Hydrometallurgical process for recovering silver from copper-electrolysis anode sludge |
| WO1990010721A1 (en) * | 1989-03-07 | 1990-09-20 | Dean Robert Butler | Recovery of gold, silver and platinum group metals with various leachants at low pulp densities |
| RU2351666C1 (en) * | 2007-07-11 | 2009-04-10 | Институт химии Дальневосточного отделения Российской академии наук (статус государственного учреждения) (Институт химии ДВО РАН) | Method of gold and silver recovery from concentrates |
| RU2607285C1 (en) * | 2015-08-17 | 2017-01-10 | Лидия Алексеевна Воропанова | Extraction of silver ions from hydrochloric acid solutions with tributyl phosphate |
| US10400306B2 (en) | 2014-05-12 | 2019-09-03 | Summit Mining International Inc. | Brine leaching process for recovering valuable metals from oxide materials |
| RU2699142C1 (en) * | 2019-03-27 | 2019-09-03 | Федеральное государственное бюджетное научное учреждение "Федеральный исследовательский центр "Красноярский научный центр Сибирского отделения Российской академии наук" (ФИЦ КНЦ СО РАН, КНЦ СО РАН) | Method of extracting silver from hydrochloric acid solutions |
| CN119662989A (en) * | 2025-02-24 | 2025-03-21 | 山西建邦集团铸造有限公司 | A method for efficient chemical separation of lead and silver |
Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US1071791A (en) * | 1911-11-23 | 1913-09-02 | Frank W Pugsley | Process of treating ores. |
| GB151952A (en) * | 1919-10-03 | 1921-05-26 | Amalgamated Zinc De Bavay S Lt | Improvements in or relating to the recovery of lead and silver from sulphide ores and metallurgical products |
| AT140214B (en) * | 1933-11-16 | 1935-01-10 | Johann Eder | Process for extracting gold from ores that are difficult to digest. |
| US3658510A (en) * | 1970-04-14 | 1972-04-25 | American Metal Climax Inc | Recovery of silver from electrolytic copper refinery slimes |
| US4269622A (en) * | 1979-12-28 | 1981-05-26 | Kerley Jr Bernard J | Recovery of precious metals from difficult ores |
| DE3145006A1 (en) * | 1980-11-18 | 1982-06-16 | Sumitomo Metal Mining Co. Ltd., Tokyo | Process for extracting gold from anode sludges |
-
1982
- 1982-03-11 CA CA000398157A patent/CA1188522A/en not_active Expired
-
1983
- 1983-03-10 EP EP83301318A patent/EP0089184A1/en not_active Withdrawn
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US1071791A (en) * | 1911-11-23 | 1913-09-02 | Frank W Pugsley | Process of treating ores. |
| GB151952A (en) * | 1919-10-03 | 1921-05-26 | Amalgamated Zinc De Bavay S Lt | Improvements in or relating to the recovery of lead and silver from sulphide ores and metallurgical products |
| AT140214B (en) * | 1933-11-16 | 1935-01-10 | Johann Eder | Process for extracting gold from ores that are difficult to digest. |
| US3658510A (en) * | 1970-04-14 | 1972-04-25 | American Metal Climax Inc | Recovery of silver from electrolytic copper refinery slimes |
| US4269622A (en) * | 1979-12-28 | 1981-05-26 | Kerley Jr Bernard J | Recovery of precious metals from difficult ores |
| DE3145006A1 (en) * | 1980-11-18 | 1982-06-16 | Sumitomo Metal Mining Co. Ltd., Tokyo | Process for extracting gold from anode sludges |
Non-Patent Citations (1)
| Title |
|---|
| Chemical Abstracts, vol. 75, no. 14, 4 October 1971, Columbus, Ohio, USA V.V. SAFONOV "Chlorination of copper-nickel anode slimes in a mediumn", page 395, column 2, Abstract 93960z & Tr. Mosk. Khim.-Teknnol. Inst. 1969, pages 161-1 * |
Cited By (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0176100A1 (en) * | 1984-09-26 | 1986-04-02 | Austria Metall Aktiengesellschaft | Hydrometallurgical process for treating electrolytic copper refinery anode slimes |
| US4666514A (en) * | 1985-01-25 | 1987-05-19 | Austria Metall Aktiengesellschaft | Hydrometallurgical process for recovering silver from copper-electrolysis anode sludge |
| EP0212453A1 (en) * | 1985-08-07 | 1987-03-04 | Noranda Inc. | Process for the recovery of gold from a precious metal bearing sludge concentrate |
| WO1990010721A1 (en) * | 1989-03-07 | 1990-09-20 | Dean Robert Butler | Recovery of gold, silver and platinum group metals with various leachants at low pulp densities |
| GB2248631A (en) * | 1989-03-07 | 1992-04-15 | Dean Robert Butler | Recovery of gold, silver and platinum group metals with various leachants at low pulp densities |
| GB2248631B (en) * | 1989-03-07 | 1993-06-09 | Dean Robert Butler | Recovery of gold, silver and platinum group metals with various leachants at low pulp densities |
| RU2351666C1 (en) * | 2007-07-11 | 2009-04-10 | Институт химии Дальневосточного отделения Российской академии наук (статус государственного учреждения) (Институт химии ДВО РАН) | Method of gold and silver recovery from concentrates |
| US10400306B2 (en) | 2014-05-12 | 2019-09-03 | Summit Mining International Inc. | Brine leaching process for recovering valuable metals from oxide materials |
| RU2607285C1 (en) * | 2015-08-17 | 2017-01-10 | Лидия Алексеевна Воропанова | Extraction of silver ions from hydrochloric acid solutions with tributyl phosphate |
| RU2699142C1 (en) * | 2019-03-27 | 2019-09-03 | Федеральное государственное бюджетное научное учреждение "Федеральный исследовательский центр "Красноярский научный центр Сибирского отделения Российской академии наук" (ФИЦ КНЦ СО РАН, КНЦ СО РАН) | Method of extracting silver from hydrochloric acid solutions |
| CN119662989A (en) * | 2025-02-24 | 2025-03-21 | 山西建邦集团铸造有限公司 | A method for efficient chemical separation of lead and silver |
Also Published As
| Publication number | Publication date |
|---|---|
| CA1188522A (en) | 1985-06-11 |
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