Method for separating platinum group metals from minerals

Abstract

The invention relates to the technical field of metal extraction, in particular to a method for separating platinum group metals from minerals, which comprises the following steps: S1, separating platinum group metal minerals; s2, platinum group metal is extracted; s3, preparation of Os; s4, Ru and Ir are separated; and S5, separating Pt, Au and Pd. According to the method for trapping the platinum group metal by adopting the pyrite powder, the sulfur content in trapped substances generated by the method reaches a certain content, the trapped substances have the characteristics of being easy to crush and decompose, and meanwhile, the method has the advantages of being simple and convenient to operate, good in separation effect, environmentally friendly and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of metal extraction, and particularly relates to a method for separating platinum group metals from minerals. Background Art

[0002] The precious metal elements in the earth's metal minerals include gold (Au), silver (Ag), palladium (Pd), platinum (Pt), osmium (Os), iridium (Ir), ruthenium (Ru), and rhodium (Rh). Among them, palladium (Pd), platinum (Pt), osmium (Os), iridium (Ir), ruthenium (Ru), and rhodium (Rh) are collectively referred to as platinum group metals. Platinum group metals are applied in various fields due to their unique physical and chemical properties. However, due to their scarce content and extremely uneven distribution, there are various inconveniences and difficulties in mining, separation, enrichment, smelting, and extraction.

[0003] At present, the separation and extraction of platinum group metals in domestic industry mainly rely on gravity separation, flotation, and their combined processes. Finally, the platinum group metal minerals enriched physically are subjected to matte smelting and converting. The traditional pyro-capture methods include lead capture, iron-nickel-copper capture, matte capture, tin capture, aluminum capture, and other metal captures. Among them, the pyro-lead capture has the disadvantages of large pollution and cumbersome operation in subsequent lead blowing, and few manufacturers use it. The disadvantages of iron-nickel-copper capture are that the alloy containing platinum group metals formed is difficult to break, has a long decomposition time, and complex processes. The disadvantages of tin and aluminum captures are the interference of tin and aluminum in subsequent acid leaching treatment.

[0004] The platinum (Pt) group elements among the precious metal elements are siderophilic elements, and have the property of being sulfurophilic rather than oxygenophilic. Moreover, the precious metals and heavy non-ferrous metals such as copper, nickel, cobalt, lead, and iron have the same crystal lattice structure and similar lattice radii. In the molten state, the precious metals can partially replace the heavy non-ferrous metals and enter the crystal lattice of heavy non-ferrous metal sulfides or form solid solution alloys or intermetallic compounds with heavy non-ferrous metals in the form of isomorphous substitution. Therefore, heavy non-ferrous metals, iron, and their alloys, as well as matte, are all effective capture agents for precious metals. Therefore, after many experimental attempts, the following method for capturing platinum group metals using pyrite powder has been studied. The sulfur content in the capture product generated by this method reaches a certain level, and it has the characteristics of being easy to break and decompose. Summary of the Invention

[0005] Based on the above background art, the present invention provides a method for separating platinum group metals from minerals.

[0006] A method for separating platinum group metals from minerals, comprising the following steps:

[0007] S1. Separation of platinum group metal minerals;

[0008] S2. Extraction of platinum group metals;

[0009] S3. Preparation of Os;

[0010] S4. Separate Ru and Ir;

[0011] S5. Separate Pt, Au and Pd.

[0012] Further, the step S1, separation of platinum group metal minerals, includes the following steps:

[0013] S1.1. Enrich the platinum group metal minerals and crush them to 150 mesh, and mix them evenly with pyrite concentrate, quicklime, sodium carbonate, starch, silica powder, saltpeter and borax in a certain proportion;

[0014] S1.2. Place the evenly mixed materials in step S1 in a smelting furnace for smelting. The smelting process is divided into the following steps:

[0015] S1.2.1. Raise the temperature of the smelting furnace to 400 - 500 °C and maintain it for 40 minutes to carbonize the starch and better adsorb the extremely fine particles in the platinum group metal minerals;

[0016] S1.2.2. Raise the temperature of the smelting furnace to 1000 °C until all the materials are melted into a molten substance. Then stir the molten substance every 10 minutes to make the molten matte better contact and capture the platinum group metals in the molten substance. After all the materials are melted into a molten substance, it needs to be maintained for 30 minutes;

[0017] S1.2.3. Raise the temperature of the smelting furnace to 1400 °C, and then stir the molten substance until it is not viscous and has good fluidity;

[0018] S1.3. Pour the smelted molten substance into a pig iron mold until it cools.

[0019] Further, the step S2, extraction of platinum group metals, includes the following steps:

[0020] S2.1. Separate the cooled molten substance into molten matte and slag;

[0021] S2.2. Crush the molten matte and mix it evenly with sodium hydroxide and 50% concentration of hydrogen peroxide in a certain proportion;

[0022] S2.3. Put the mixture formed in step S5 into a 316 stainless steel container and heat it in a muffle furnace;

[0023] S2.4. Slowly heat the temperature of the muffle furnace to 400 - 700 °C and maintain it for 4 hours, and take it out and stir it several times during this period;

[0024] S2.5. Raise the temperature of the muffle furnace to 760 - 860 °C and maintain it for 2 hours. During this period, a mixed gas of Os and Ru will be generated;

[0025] S2.6. Connect the mixed gas to the Os absorption system and introduce it into sodium hydroxide solution to recover the volatile Os gas; connect the mixed gas to the Ru absorption system, wash it with distilled water and then introduce it into a 4 mol / L hydrochloric acid solution containing 3% ethanol to absorb the Ru gas; absorb and filter the remaining gas through sodium sulfide solution;

[0026] S2.7. Take out the solid generated in the above steps, cool and crush it, then mix it with water at a solid-liquid ratio of 1:10, stir and leach for 4 hours and then filter to obtain an aqueous solution containing Os, Ru, Pt and a filter residue containing IrO2;

[0027] S2.8. Add appropriate ethanol to the alkaline solution containing Na2RuO4, Na2OsO4 and Na2PtO4 at room temperature and let it stand for 6 h for precipitation to obtain Ru. The remaining solution is neutralized with sulfuric acid. At this time, Na2OsO4 and Na2PtO4 are respectively precipitated as OsO2 precipitate and PtO2 precipitate;

[0028] S2.9. After solid-liquid separation of the precipitate, return the OsO2 precipitate and PtO2 precipitate to steps S2.5 and S2.6, recover the volatile Os gas again, introduce it into sodium hydroxide solution to recover the volatile Os gas, and then the remaining solid is Pt. The filtrate is treated with Na2S and then discharged.

[0029] Further, step S3, preparation of Os, includes the following steps:

[0030] S3.1. Filter the Os absorbed by sodium hydroxide and then add excessive solid ammonium chloride to the filtered liquid to generate yellow ammonium diosmium chloride precipitate. Suction-filter the generated precipitate, wash it with anhydrous ethanol solution, and then crush the filter cake and put it into a vacuum furnace to dry at 80 °C;

[0031] S3.2. After drying, first introduce argon to drive away air, then introduce hydrogen and heat up to 500 °C until there is no white smoke;

[0032] S3.3. Continue to heat up to 800 °C, keep warm for 3 hours, then cool to 400 °C under hydrogen protection, then introduce argon to drive away hydrogen, and continue to cool to room temperature to take out the reduction product;

[0033] S3.4. Wash the reduction product clean with distilled water, boil it in a 6 mol / L hydrochloric acid solution at 90 °C for 30 minutes, filter and wash it with distilled water until neutral, put it into a vacuum furnace and dry it at 600 °C for 2 hours under hydrogen protection to obtain osmium powder, and then cool the osmium powder to room temperature under argon protection and take it out for vacuum packaging to prevent oxidation.

[0034] Further, step S4, separation of Ru and Ir, includes the following steps:

[0035] S4.1, Preparation of Ru;

[0036] S4.2, Preparation of Ir.

[0037] Furthermore, the step S4.1, Preparation of Ru, includes the following steps:

[0038] S4.1.1, Dissolve Ru(OH)4 precipitated with ethanol in hydrochloric acid, and after dissolution, place it on an adjustable electric furnace and heat it to 70 °C, then evaporate and concentrate to 1 / 3 of the original solution volume;

[0039] S4.1.2, Adjust the pH to 1 - 1.5 with 10% sodium hydroxide solution, then introduce it into the reaction kettle, and connect the Ru absorption system containing 4 mol / L and 3% ethanol solution. Heat the reaction kettle to 90 °C, and then slowly add 20% sodium hydroxide solution and 20% sodium bromide solution to increase the pH. When a large amount of RuO4 gas is distilled out, stop adding sodium hydroxide, and continue to add sodium bromide solution until no more distilled gas is produced;

[0040] S4.1.3, Conduct the operation of oxidizing and removing Os. Pour the Ru absorption solution into the distillation kettle, and connect the Os absorption device. Heat and concentrate, and at the same time drop in hydrogen peroxide to remove Os. OsO4 volatilizes and is absorbed until the thiourea cotton ball test shows no red color;

[0041] S4.1.4, After removing Os, continue to heat and concentrate the ruthenium solution to 2 / 5 of the original solution volume, then add ammonium chloride solid to form a black - red ammonium chlororuthenate precipitate. At this time, the supernatant should be colorless;

[0042] S4.1.5, Filter the precipitate, wash it with absolute ethanol 2 - 3 times and then dry it, then put it into a muffle furnace and calcine it at 400 °C until no smoke is produced, and then cool it and place it in a vacuum furnace;

[0043] S4.1.6, Heat the vacuum furnace to 400 °C, then introduce argon to drive away air, and then introduce hydrogen to drive away argon. Heat it to 750 °C - 900 °C and reduce it for 3 - 4 hours. Cool it to 400 °C under hydrogen protection, and then change to argon for heat preservation until room temperature to obtain gray sponge ruthenium;

[0044] S4.1.7, Boil the sponge ruthenium with 6 mol / L hydrochloric acid for 30 minutes, filter it, wash it with distilled water until neutral, and then dry it to obtain ruthenium powder with a content of 99.9%.

[0045] Furthermore, the step S4.2, Preparation of Ir, includes the following steps:

[0046] S4.2.1. First, react the filter residue containing IrO2 with sulfuric acid at a concentration of 1.7 - 1.8 mol / L at room temperature with a solid-liquid ratio of 1:10 for 1 hour, then filter for the first leaching. Next, use a sulfuric acid solution at a concentration of 2 mol / L with a solid-liquid ratio of 1:40, heat and react between 75°C and 80°C for 4 hours, and then filter for the second leaching;

[0047] S4.2.2. Dissolve the enriched IrO2 with hydrochloric acid at a concentration of 8 mol / L at a solid-liquid ratio of 1:15, heat at 90°C for 3 hours, cool and filter. Then reheat the filtrate to 80°C, and slowly add a 10% Na2S solution while stirring, and Ir is reduced to a trivalent chloro complex;

[0048] S4.2.3. For the remaining Pt, Au, and Pd after the eutectic reaction with sodium hydroxide and sodium peroxide, form a sulfide precipitate. Filter the precipitate, wash it with absolute ethanol 2 - 3 times, dry it at 80°C, and then place it in a vacuum furnace;

[0049] S4.2.4. First, heat the vacuum furnace to 300°C, then introduce argon to drive out air, and then introduce hydrogen to drive out argon. After that, heat to 400°C - 450°C and reduce for 3 - 4 hours. Cool to 300°C under hydrogen protection, and then change to argon for heat preservation until room temperature to obtain a mixed sponge-like alloy powder of IrO2, Pt, Au, and Pd;

[0050] S4.2.5. Boil the alloy powder with hydrochloric acid at a concentration of 8 mol / L for 30 minutes, filter, wash it with distilled water until neutral, and then dry it to obtain a mixed alloy powder of Pt, Au, and Pd;

[0051] S4.2.6. After the hydrochloric acid solution is cooled again, heat it to 80°C again, and then slowly add a 10% Na2S solution to reduce Ir to a trivalent chloro complex again. Filter the chloro complex, wash it with absolute ethanol 3 times, dry it at 80°C, and then place it in a vacuum furnace for vacuum reduction again to obtain iridium powder with a content of 99.9%.

[0052] Furthermore, the step S5 of separating Pt, Au, and Pd includes the following steps:

[0053] S5.1. For the mixed alloy powder of Pt, Au, and Pd, dissolve the palladium in the alloy powder with dilute nitric acid, adjust the pH value to 3 - 4 with sodium hydroxide, and then reduce sponge palladium with hydrazine hydrate. Boil the reduced sponge palladium with hydrochloric acid at a concentration of 3 mol / L to remove impurities, then wash it with distilled water until neutral, and then dry it at 80°C, and then it can be placed in a gold melting furnace to be melted into palladium;

[0054] S5.2. Dissolve the remaining Pt and Au mixed alloy in aqua regia. Pass a conduit into the aqua regia solution containing Pt and Au, connect the other side of the conduit to a gas generation device, react with the gas generation device to produce SO2 gas, and pass the SO2 into the aqua regia liquid containing Pt and Au. Brown gold powder precipitate will be generated. Filter the precipitate, put it into dilute nitric acid solution for impurity removal, filter, wash, and dry after impurity removal, and then put it into a gold melting furnace to smelt gold;

[0055] S5.3. Add saturated ammonium chloride solution to the remaining liquid in the above steps. Orange ammonium chloroplatinate precipitate will be formed. Filter, wash, and dry it, and then place it in a vacuum furnace. First, heat the vacuum furnace to 300 °C, then pass argon to drive away air, and then pass hydrogen to drive away argon. Then, heat it to 400 - 450 °C and reduce for 3 - 4 hours. Cool down to 300 °C under hydrogen protection, and then use argon to keep the temperature at room temperature to obtain sponge platinum. Boil the sponge platinum with 8 mol / L hydrochloric acid for 30 minutes, filter, wash it with distilled water until neutral, and then dry it to obtain platinum powder with a content of 99.9%. Place it in a gold melting furnace to smelt platinum.

[0056] Further, in step S4.2.1, the two-stage countercurrent leaching method is adopted. After these two leachings, the purity of the remaining IrO2 is above 95%.

[0057] Advantages of the present invention:

[0058] The method for capturing platinum group metals with pyrite powder in the present invention has the characteristic that the sulfur content in the generated capture product reaches a certain level and it is easy to break and decompose. At the same time, this method has the advantages of simple operation, good separation effect, and environmental protection. Specific embodiments

[0059] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0060] A method for separating platinum group metals from minerals, comprising the following steps:

[0061] S1. Separation of platinum group metal minerals, comprising the following steps:

[0062] S1.1. Enrich the platinum group metal minerals and crush them to 150 meshes, and mix them evenly with pyrite concentrate, quicklime, sodium carbonate, starch, silica powder, saltpeter, and borax in a certain proportion;

[0063] S1.2. Place the uniformly mixed materials in a smelting furnace for smelting, and the smelting process is divided into the following steps:

[0064] S1.2.1. Raise the temperature of the smelting furnace to 400 - 500 °C and maintain it for 40 minutes to carbonize the starch and better adsorb the extremely fine particles in the platinum group metal minerals;

[0065] S1.2.2. Raise the temperature of the smelting furnace to 1000 °C until all the materials are melted into a molten substance, and then stir the molten substance every 10 minutes to make the molten matte better contact and capture the platinum group metals in the molten substance. After all the materials are melted into a molten substance, it needs to be maintained for 30 minutes;

[0066] S1.2.3. Raise the temperature of the smelting furnace to 1400 °C, and then stir the molten substance until it is not viscous and has good fluidity;

[0067] S1.3. Pour the smelted molten substance into a pig iron mold until it cools;

[0068] In this embodiment, the main reactions during the smelting process are as follows:

[0069] MeS + 3O2 == MeO + 3SO2

[0070] MeO + C == Me + CO2

[0071] MeS + Fe3O4 + 4C == Me + 3FeS + 4CO

[0072] MeS + CaO + C == Me + CaS + CO

[0073] Fe3O4 + 4C == 3Fe + 4CO

[0074] 2CaO + 4SO2 + O2 == 2CaSO4

[0075] 2CO + O2 == 2CO2

[0076] CaO + SiO2 == CaO*SiO2

[0077] 2FeO + SiO2 == 2FeO*SiO2

[0078] The slag mainly composed of FeO*SiO2, CaO*SiO2, and SiO2 is generated by the above reactions, and the platinum group metals are enriched in the molten matte.

[0079] In this embodiment, the waste gas generated by smelting is mainly sulfur dioxide gas, as well as the oxidized volatile substances of osmium and ruthenium. The sulfur dioxide gas can be recycled as raw material for making sulfuric acid. The oxidized volatile substance of osmium can be recycled with sodium hydroxide solution, and the ruthenium oxide can be recycled with 3% ethanol solution.

[0080] S2. Extract platinum group metals, including the following steps:

[0081] S2.1. Separate the cooled molten material into molten matte and slag;

[0082] S2.2. After crushing the molten matte, mix it evenly with sodium hydroxide and 50% hydrogen peroxide in a certain proportion;

[0083] S2.3. Put the mixture formed in step S5 into a 316 stainless steel container and heat it in a muffle furnace;

[0084] S2.4. Slowly heat the temperature of the muffle furnace to 400 - 700 °C, keep it for 4 hours, and take it out and stir several times during this period;

[0085] S2.5. Raise the temperature of the muffle furnace to 760 - 860 °C and keep it for 2 hours. During this period, a mixed gas of Os and Ru will be generated;

[0086] S2.6. Connect the mixed gas to the Os absorption system and pass it into sodium hydroxide solution to recover the volatile Os gas; connect the mixed gas to the Ru absorption system, pass it through distilled water for washing and then into a 4 mol / L hydrochloric acid solution containing 3% ethanol to absorb the Ru gas; pass the remaining gas through sodium sulfide solution for absorption and filtration;

[0087] S2.7. Take out the solid generated in the above steps, cool and crush it, then mix it with water according to the solid-liquid ratio of 1:10, stir and leach for 4 hours, and then filter to obtain an aqueous solution containing Os, Ru, and Pt and a filter residue containing IrO2;

[0088] S2.8. Add an appropriate amount of ethanol to the alkaline solution containing Na2RuO4, Na2OsO4, and Na2PtO4 at room temperature and let it stand for 6 h for precipitation to obtain Ru. Neutralize the remaining solution with sulfuric acid. At this time, Na2OsO4 and Na2PtO4 are respectively precipitated as OsO2 precipitate and PtO2 precipitate;

[0089] S2.9. After solid-liquid separation of the precipitate, return the OsO2 precipitate and PtO2 precipitate to step S2.5 and step S2.6 to recover the volatile Os gas again, and pass it into sodium hydroxide solution to recover the volatile Os gas. Then the remaining solid is Pt, and the filtrate is treated with Na2S and discharged;

[0090] In this embodiment, the main reactions are as follows:

[0091] 2NaOH + H2O2 == Na2O2 + H2O

[0092] FeS + NaOH = Na2S + Fe(OH)

[0093] 2Fe(OH)3 ==== heated ==== Fe2O3 + 3H2O

[0094] RuO2 + Na2O2 + 2NaOH ---- Na2RuO4 + Na2O + H2O

[0095] 3Na2O2 + Ru ---- NaRuO4 + Na2O

[0096] OsO2 + 6Na2O2 + 6NaOH ---- 2Na2OsO4 + 5Na2O + H2O

[0097] Ir + nNa2O2 ---- IrO2.nNa2O + (n - 2) / 2O2

[0098] The preparation of S3 and Os includes the following steps:

[0099] S3.1. Filter the Os absorbed by sodium hydroxide, then add excessive solid ammonium chloride to the filtered liquid to generate yellow ammonium dichloride osmium precipitate. After suction filtration of the generated precipitate, wash it with anhydrous ethanol solution, and then crush the filter cake and dry it in a vacuum furnace at 80 °C;

[0100] S3.2. After drying, first introduce argon to drive away air, then introduce hydrogen and raise the temperature to 500 °C until there is no white smoke;

[0101] S3.3. Continue to raise the temperature to 800 °C, keep warm for 3 hours, then cool to 400 °C under hydrogen protection, then introduce argon to drive away hydrogen, and continue to cool to room temperature to take out the reduction product;

[0102] S3.4. Wash the reduction product clean with distilled water, boil it with 6 mol / L hydrochloric acid solution at 90 °C for 30 minutes, filter and wash it with distilled water until neutral, put it into a vacuum furnace and dry it at 600 °C for 2 hours under hydrogen protection to obtain osmium powder, and then cool the osmium powder to room temperature under argon protection and take it out for vacuum packaging to prevent oxidation;

[0103] S4. Separate Ru and Ir, including the following steps:

[0104] S4.1. The preparation of Ru includes the following steps:

[0105] S4.1.1. Dissolve the Ru(OH)4 precipitated with ethanol with hydrochloric acid, and after dissolution, place it on an adjustable electric furnace and heat it to 70 °C for evaporation and concentration to 1 / 3 of the original solution volume;

[0106] S4.1.2. After adjusting the pH to 1 - 1.5 with a 10% sodium hydroxide solution, introduce it into the reaction kettle and connect the Ru absorption system containing a 4 mol / L and 3% ethanol solution. Heat the reaction kettle to 90°C, and then slowly add a 20% sodium hydroxide solution and a 20% sodium bromide solution to increase the pH. Stop adding sodium hydroxide when a large amount of RuO4 gas is distilled out, and continue to add the sodium bromide solution until no distillation gas is produced;

[0107] S4.1.3. Conduct the operation of oxidizing and removing Os. Pour the Ru absorption solution into the distillation kettle and connect the Os absorption device. Heat and concentrate it, and at the same time drop in hydrogen peroxide to remove Os. OsO4 volatilizes and is absorbed until it does not turn red when checked with a thiourea cotton ball;

[0108] S4.1.4. After removing Os, continue to heat and concentrate the ruthenium solution to 2 / 5 of the original solution volume, then add solid ammonium chloride to form a black - red ammonium hexachlororuthenate precipitate. At this time, the supernatant should be colorless;

[0109] S4.1.5. Filter the precipitate, wash it 2 - 3 times with absolute ethanol and then dry it, then put it into a muffle furnace and calcine it at 400°C until no smoke is produced, and then cool it and place it in a vacuum furnace;

[0110] S4.1.6. Heat the vacuum furnace to 400°C, then introduce argon to drive away air, and then introduce hydrogen to drive away argon. Raise the temperature to 750°C - 900°C and reduce it for 3 - 4 hours. Cool it to 400°C under hydrogen protection, and then change to argon for heat preservation until room temperature to obtain gray sponge ruthenium;

[0111] S4.1.7. Boil the sponge ruthenium with 6 mol / L hydrochloric acid for 30 minutes, filter it, wash it with distilled water until neutral, and then dry it to obtain ruthenium powder with a content of 99.9%;

[0112] S4.2. Preparation of Ir, including the following steps:

[0113] S4.2.1. First, react the filter residue containing IrO2 with 1.7 - 1.8 mol / L sulfuric acid at room temperature with a solid - liquid ratio of 1:10 for 1 hour, filter for the first leaching, and then use a 2 mol / L sulfuric acid solution with a solid - liquid ratio of 1:40, heat and react between 75°C - 80°C for 4 hours, and filter for the second leaching;

[0114] In this embodiment, the step S4.2.1 adopts a two - stage counter - current leaching method. After these two leachings, the remaining IrO2 purity is above 95%. The ferrous sulfate solution obtained by the reaction of sulfuric acid and molten matte can be used to prepare ferrous sulfate crystals.

[0115] S4.2.2. Dissolve the enriched IrO₂ in 8 mol / l hydrochloric acid at a solid-liquid ratio of 1:15, heat it at 90 °C for 3 hours, cool it and filter it. Then reheat the filtrate to 80 °C, and slowly add 10% Na₂S solution while stirring. Ir is reduced to trivalent chloro complex;

[0116] S4.2.3. For the remaining Pt, Au, and Pd after the eutectic reaction with sodium hydroxide and sodium peroxide, form sulfide precipitates. Filter the precipitates, wash them 2 - 3 times with absolute ethanol, dry them at 80 °C, and then place them in a vacuum furnace;

[0117] S4.2.4. First, heat the vacuum furnace to 300 °C, then introduce argon to drive out air, and then introduce hydrogen to drive out argon. After that, heat it to 400 °C - 450 °C and reduce for 3 - 4 hours. Cool it to 300 °C under hydrogen protection, and then change to argon to keep the temperature at room temperature to obtain a mixed sponge-like alloy powder of IrO₂, Pt, Au, and Pd;

[0118] S4.2.5. Boil the alloy powder in 8 mol / L hydrochloric acid for 30 minutes, filter it, wash it with distilled water until neutral, and then dry it to obtain a mixed alloy powder of Pt, Au, and Pd;

[0119] S4.2.6. After cooling the hydrochloric acid solution again, heat it to 80 °C again, and then slowly add a 10% Na₂S solution to reduce Ir to trivalent chloro complex again. Filter the chloro complex, wash it 3 times with absolute ethanol, dry it at 80 °C, and then place it in a vacuum furnace for vacuum reduction again to obtain iridium powder with a content of 99.9%;

[0120] S5. Separate Pt, Au, and Pd, including the following steps:

[0121] S5.1. For the mixed alloy powder of Pt, Au, and Pd, dissolve palladium in the alloy powder with dilute nitric acid, adjust the pH value to 3 - 4 with sodium hydroxide, and then reduce sponge palladium with hydrazine hydrate. Boil the reduced sponge palladium in 3 mol / L hydrochloric acid to remove impurities, then wash it with distilled water until neutral, and then dry it at 80 °C. Then it can be placed in a gold melting furnace to melt into palladium. In this example, the concentration of hydrazine hydrate is 80%;

[0122] S5.2. Dissolve the remaining mixed alloy of Pt and Au in aqua regia. Pass a conduit into the aqua regia solution containing Pt and Au, and connect the other side of the conduit to a gas generation device. React with the gas generation device to generate SO₂ gas. When SO₂ is passed into the aqua regia liquid containing Pt and Au, brown gold powder precipitates will be produced. Filter the precipitate, put it into dilute nitric acid solution to remove impurities, filter, wash, and dry it after impurity removal, and then put it into a gold melting furnace to melt gold. In this example, the chemical reaction equation is: Na₂SO₃ + H₂SO₄ (concentrated) === Na₂SO₄ + H₂O + SO₂↑;

[0123] S5.3. Add saturated ammonium chloride solution to the remaining liquid of the above steps. Orange ammonium chloroplatinate precipitate will form. Filter, wash, and dry it. Then place it in a vacuum furnace. First, heat the vacuum furnace to 300 °C, then introduce argon to drive out air, and then introduce hydrogen to drive out argon. After that, heat it to 400 - 450 °C and reduce for 3 - 4 hours. Cool down to 300 °C under hydrogen protection, and then change to argon for heat preservation until room temperature. Sponge platinum can be obtained. Boil the sponge platinum with 8 mol / L hydrochloric acid for 30 minutes, filter, wash it with distilled water until neutral, and then dry it to obtain platinum powder with a content of 99.9%. Place it in a gold melting furnace for melting to obtain platinum.

[0124] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, for those of ordinary skill in the art, it is still possible to modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions required to be protected by the present invention.

Claims

1. A method for separating platinum group metals from minerals, characterized in that, It includes the following steps: S1. Separation of platinum group metal minerals; S2. Extraction of platinum group metals; S3. Preparation of Os; S4. Separation of Ru and Ir; S5. Separation of Pt, Au and Pd.

2. The method for separating platinum group metals from minerals according to claim 1, characterized in that, The step S1, separation of platinum group metal minerals, includes the following steps: S1.

1. Enrich the platinum group metal minerals and crush them to 150 mesh, and mix them evenly with pyrite concentrate, quicklime, sodium carbonate, starch, silica powder, saltpeter and borax in a certain proportion; S1.

2. Place the evenly mixed materials in step S1 in a smelting furnace for smelting. The smelting process is divided into the following steps: S1.2.

1. Raise the temperature of the smelting furnace to 400 - 500 °C and keep it for 40 minutes to carbonize the starch and better adsorb the extremely fine particles in the platinum group metal minerals; S1.2.

2. Raise the temperature of the smelting furnace to 1000 °C until all the materials are melted into a molten substance, and then stir the molten substance every 10 minutes to make the molten matte better contact and capture the platinum group metals in the molten substance. After all the materials are melted into a molten substance, it needs to be kept for 30 minutes; S1.2.

3. Raise the temperature of the smelting furnace to 1400 °C, and then stir the molten substance until it is not viscous and has good fluidity; S1.

3. Pour the smelted molten substance into a pig iron mold until it cools.

3. The method for separating platinum group metals from minerals according to claim 2, wherein, The step S2, extraction of platinum group metals, includes the following steps: S2.

1. Separate the cooled molten substance into molten matte and slag; S2.

2. Crush the molten matte and mix it evenly with sodium hydroxide and 50% hydrogen peroxide in a certain proportion; S2.

3. Put the mixture formed in step S5 into a 316 stainless steel container and heat it in a muffle furnace; S2.

4. Slowly heat the temperature of the muffle furnace to 400 - 700 °C and keep it for 4 hours, and take it out and stir it several times during this period; S2.

5. Raise the temperature of the muffle furnace to 760 - 860 °C and keep it for 2 hours. During this period, a mixed gas of Os and Ru will be generated; S2.

6. Connect the mixed gas to the Os absorption system and introduce it into sodium hydroxide solution to recover the volatile Os gas; connect the mixed gas to the Ru absorption system, introduce it into distilled water for washing and then into a 4 mol / L hydrochloric acid solution containing 3% ethanol to absorb the Ru gas; absorb and filter the remaining gas through sodium sulfide solution; S2.

7. Take out the solid generated in the above steps, cool and crush it, and then mix it with water according to a solid-liquid ratio of 1:10, stir and leach for 4 hours and then filter to obtain an aqueous solution containing Os, Ru, Pt and a filter residue containing IrO2; S2.

8. Add an appropriate amount of ethanol to the alkaline solution containing Na2RuO4, Na2OsO4 and Na2PtO4 at room temperature and let it stand for 6 h to precipitate Ru. The remaining solution is neutralized with sulfuric acid. At this time, Na2OsO4 and Na2PtO4 are respectively precipitated as OsO2 precipitate and PtO2 precipitate; S2.

9. After the precipitation solid-liquid separation, return the OsO2 precipitate and PtO2 precipitate to steps S2.5 and S2.6, recollect the volatilized Os gas, introduce it into the sodium hydroxide solution to recover the volatilized Os gas, and then the remaining solid is Pt. The filtrate is treated with Na2S and then discharged.

4. The method for separating platinum group metals from minerals according to claim 3, characterized in that, The said step S3, preparation of Os, includes the following steps: S3.

1. Filter the Os absorbed by sodium hydroxide, then add excessive solid ammonium chloride to the filtered liquid to generate a yellow ammonium osmium dichloride precipitate. Suction-filter the generated precipitate, wash it with an anhydrous ethanol solution, and then crush the filter cake and put it into a vacuum furnace to dry at 80 °C. S3.

2. After drying, first introduce argon to drive away the air, then introduce hydrogen and heat up to 500 °C until there is no white smoke. S3.

3. Continue to heat up to 800 °C, keep warm for 3 hours, then cool down to 400 °C under the protection of hydrogen, then introduce argon to drive away hydrogen, and continue to cool down to room temperature to take out the reduction product. S3.

4. Wash the reduction product clean with distilled water, boil it in a 6 mol / L hydrochloric acid solution at 90 °C for 30 minutes, filter and wash it with distilled water until neutral, put it into a vacuum furnace and dry it at 600 °C for 2 hours under the protection of hydrogen to obtain osmium powder, and then cool the osmium powder to room temperature under the protection of argon and take it out for vacuum packaging to prevent oxidation.

5. A method for separating platinum group metals from minerals according to claim 4, characterized in that, The said step S4, separation of Ru and Ir, includes the following steps: S4.

1. Preparation of Ru; S4.

2. Preparation of Ir.

6. A method for separating platinum group metals from minerals according to claim 5, characterized in that, The said step S4.1, preparation of Ru, includes the following steps: S4.1.

1. Dissolve the Ru(OH)4 precipitated with ethanol with hydrochloric acid, and after dissolution, place it on an adjustable electric furnace and heat it to 70 °C, and evaporate and concentrate it to 1 / 3 of the original solution volume. S4.1.

2. After adjusting the pH to 1 - 1.5 with a 10% concentration sodium hydroxide solution, put it into a reaction kettle, and connect it to a Ru absorption system containing a 4 mol / L and 3% ethanol solution. Heat the reaction kettle to 90 °C, and then slowly add a 20% concentration sodium hydroxide solution and a 20% concentration sodium bromide solution to increase the pH. When a large amount of RuO4 gas is distilled out, stop adding sodium hydroxide, and continue to add the sodium bromide solution until no distilled gas is generated. S4.1.

3. Conduct an operation to oxidize and remove Os. Pour the Ru absorption liquid into a distillation kettle, connect an Os absorption device, heat and concentrate it, and at the same time drip hydrogen peroxide to remove Os. OsO4 volatilizes and is absorbed until it is checked with a thiourea cotton ball and does not turn red. S4.1.

4. After removing Os, continue to heat and concentrate the ruthenium solution to 2 / 5 of the original solution volume, add solid ammonium chloride to generate a black-red ammonium hexachlororuthenate precipitate. At this time, the supernatant should be colorless. S4.1.

5. Filter the precipitate, wash it with anhydrous ethanol 2 - 3 times and then dry it, and then put it into a muffle furnace and calcine it at 400 °C until there is no smoke, and then cool it and place it in a vacuum furnace. S4.1.

6. Heat the vacuum furnace to 400 °C, then introduce argon to drive out the air, and then introduce hydrogen to drive out the argon. Heat to 750 °C - 900 °C and reduce for 3 - 4 hours. Cool to 400 °C under hydrogen protection, and then change to argon for heat preservation until room temperature to obtain gray sponge ruthenium; S4.1.

7. Boil the sponge ruthenium with 6 mol / L hydrochloric acid for 30 minutes, filter and wash with distilled water until neutral, and then dry to obtain ruthenium powder with a content of 99.9%.

7. A method for separating platinum group metals from minerals as claimed in claim 6, characterized in that, The step S4.2, the preparation of Ir, includes the following steps: S4.2.

1. React the filter residue containing IrO2 with 1.7 - 1.8 mol / L sulfuric acid at room temperature with a solid-liquid ratio of 1:10 for 1 hour, filter for the first leaching, and then use 2 mol / L sulfuric acid solution with a solid-liquid ratio of 1:40, heat and react between 75 °C - 80 °C for 4 hours, and filter for the second leaching; S4.2.

2. Dissolve the enriched IrO2 with 8 mol / L hydrochloric acid at a solid-liquid ratio of 1:15, heat to 90 °C and dissolve for 3 hours, cool and filter, then reheat the filtrate to 80 °C, and slowly add 10% Na2S solution while stirring, and Ir is reduced to a trivalent chlorine complex; S4.2.

3. React the remaining Pt, Au, and Pd with sodium hydroxide and sodium peroxide by melting to form sulfide precipitates. Filter the precipitates, wash with anhydrous ethanol 2 - 3 times, dry at 80 °C, and then place in a vacuum furnace; S4.2.

4. Heat the vacuum furnace to 300 °C first, then introduce argon to drive out the air, and then introduce hydrogen to drive out the argon. Then heat to 400 °C - 450 °C and reduce for 3 - 4 hours. Cool to 300 °C under hydrogen protection, and then change to argon for heat preservation until room temperature to obtain a mixed sponge-like alloy powder of IrO2, Pt, Au, and Pd; S4.2.

5. Boil the alloy powder with 8 mol / L hydrochloric acid for 30 minutes, filter and wash with distilled water until neutral, and then dry to obtain a mixed alloy powder of Pt, Au, and Pd; S4.2.

6. Re-cool the hydrochloric acid solution and then heat it to 80 °C again, and then slowly add a 10% Na2S solution to reduce Ir to a trivalent chlorine complex again. Filter the chlorine complex, wash with anhydrous ethanol 3 times, dry at 80 °C, and then place in a vacuum furnace for vacuum reduction again to obtain iridium powder with a content of 99.9%.

8. A method for separating platinum group metals from minerals according to claim 7, characterized in that, The step S5, the separation of Pt, Au, and Pd, includes the following steps: S5.

1. Dissolve the palladium in the alloy powder of Pt, Au, and Pd with dilute nitric acid, adjust the pH value to 3 - 4 with sodium hydroxide, and then reduce sponge palladium with hydrazine hydrate. Boil the reduced sponge palladium with 3 mol / L hydrochloric acid to remove impurities, then wash with distilled water until neutral, and then dry at 80 °C, and then it can be placed in a gold melting furnace to be melted into palladium; S5.

2. Dissolve the remaining Pt and Au alloy in aqua regia. Pass a conduit into the aqua regia solution containing Pt and Au. Connect the other side of the conduit to a gas generation device. React with the gas generation device to produce SO2 gas. After passing SO2 into the aqua regia liquid containing Pt and Au, brown gold powder precipitate will be generated. Filter the precipitate and put it into a dilute nitric acid solution for impurity removal. After impurity removal, filter, wash, and dry it, and then put it into a gold melting furnace to smelt gold; S5.

3. Add saturated ammonium chloride solution to the remaining liquid in the above steps. Orange ammonium chloroplatinate precipitate will be formed. Filter, wash, and dry it. Then place it in a vacuum furnace. First, heat the vacuum furnace to 300 °C, then pass argon to drive out air, and then pass hydrogen to drive out argon. Then, heat it to 400 - 450 °C and reduce it for 3 - 4 hours. Cool it to 300 °C under hydrogen protection, and then use argon to keep it at room temperature to obtain sponge platinum. Boil the sponge platinum with 8 mol / L hydrochloric acid for 30 minutes, filter, wash it with distilled water until neutral, and then dry it to obtain platinum powder with a content of 99.9%. Place it in a gold melting furnace to smelt platinum.

9. The method for separating platinum group metals from minerals according to claim 7, characterized in that, The step S4.2.1 adopts a two-stage countercurrent leaching method. After these two leachings, the purity of the remaining IrO2 is above 95%.