First, the gold recycling technology [1] from the gold-plated cultural relics copper recycling materials recycling research institute using the oxidative roasting method to recover gold from the scrap gold relics copper. The copper material of the scrap gold deposit is placed in a special baking furnace, and is calcined at 1000 C for 30 minutes at a constant temperature. It is taken out into water, and the gold layer is attached to the scale of copper oxide and detached from the copper substrate. Then it is dissolved in dilute sulfuric acid, and the dissolved slag is separated to purify the gold. This method features no pollution when roasting. This method is used to treat 300 kg of waste cultural relics and recover 1.5 kg of gold. The gold recovery rate is >98%, the matrix copper recovery rate is >95%, and the by-product copper sulfate can be used as an insecticide. [2] Recovery of gold from waste electronic components The Beijing Rare Metals Metallurgical Plant uses the I2-Nal-H2O system. The gold plating on the waste components is eroded, and the gold is recovered by iron replacement or sodium sulfite reduction. Acidification with sulfuric acid, oxidation of potassium chlorate to regenerate iodine . The Institute of Materials Recycling and Utilization has developed a new process for electrolytic gold withdrawal. Thiourea and sodium sulfite are used as electrolytes, graphite is used as a cathode plate, and gold-plated scrap is used as an anode for electrolytic gold withdrawal. By electrolysis, the gold on the coating is anodized to Au+, which forms a complex cation Au[cs(NH2)]2+ with thiourea, which is then reduced to gold by sodium sulfite, sinks to the bottom of the tank, and the gold-containing precipitate is separated and purified. Pure gold powder. The base material can recover nickel cobalt . The recovery rate of this process gold is 97~98%. Product gold purity>99.95%. [3] the spent catalyst recovered from the gold and palladium Kunming Institute of Precious Metals oxidant repeatedly using hydrochloric acid leaching the gold and palladium into the solution, zinc powder substitution, hydrochloric acid dissolved oxidizing agent, reduction of oxalic acid to give the pure powder; reduction method by conventional liquor Purify palladium. The purity of gold and palladium can reach 99.9%. The recovery rates were 97% and 96%, respectively. Has applied for a Chinese patent.
Second, the silver recycling technology [1] electrolytic silver-returning new technology materials recycling research institute to design electrolytic silvering equipment, with graphite plate as the cathode, stainless steel roller as the anode, the drum has many fine holes. Sodium citrate and sodium sulfite are electrolytes, and silver plated parts enter from the head end of the drum and are sent out from the end of the drum. The silver on the surface of the plated part enters the electrolyte, and the substrate of the plated part is intact and can be returned to the electroplating. The silver recovery rate is 97-98%, and the silver powder purity is 99.9%. [2] Recycling of waste silver-zinc battery The waste silver-zinc battery contains 52.55% silver and 42.7% zinc. Zinc is a negative electrode, and silver oxide is a positive electrode coated on a copper mesh skeleton. The Materials Recycling Institute uses zinc dilute sulfuric acid and copper and silver powder to directly melt ingots. When the dilute sulfuric acid is immersed in copper, an oxidizing agent is added, the zinc-containing liquid is concentrated and crystallized to produce zinc sulfate, and the copper-containing liquid is concentrated and crystallized to produce copper sulfate The zinc recovery rate is >98%, the silver recovery rate is 98%, and the silver ingot purity is >99%. [3] Recovering Silver from Waste Films Kunming Institute of Precious Metals uses a dilute sulfuric acid solution to elute a silver-containing emulsion layer on a color plate, a chloride salt to heat precipitate silver halide, a chlorinated or organic solvent to remove organic matter, and an alkaline medium for sugar. The solid suspension is reduced to obtain pure silver. The purity of silver is 99.9%, and the direct yield is 98%. This law has applied for a patent. The Institute of Materials Recycling and Utilization (formerly the Institute of Materials Recycling and Utilization of the Ministry of Internal Trade) used sodium thiosulfate solution to dissolve silver halide on waste film. During the dissolution process, an inhibitor was added to prevent the dissolution of gelatin on the film, and the solution was recovered by electrolysis. Recycling of the base. The silver leaching rate is >99%, the recovery rate is 98%, and the silver purity is 99.9%. This method has been applied to industrial production. [4] After the silver photosensitive material is recovered from the waste fixing liquid, after exposure, development, and fixing, about 70-80% of the silver on the black and white sheet enters the fixing liquid, and almost all of the silver of the color sheet enters the fixing liquid. The recovery of silver from the waste fixing solution has been highly valued at home and abroad, and a large amount of research work has been carried out. The recovery methods used are ion precipitation, electrolysis, metal replacement, drug reduction, and ion exchange. The advantage of the electrolysis method is that the fixing solution after silver extraction can be returned for fixing use. The larger film studios in the mainland use recycled silver from this method.
Third, the method of recovering a platinum group metal technology [1] in nitric acid plants of recovering platinum nitric acid production of platinum, of palladium, rhodium ternary alloy catalyst net production loss of the noble metal is deposited in an oxidizing most of ashes. Kunming Precious Metal Research Institute and Taiyuan Fertilizer Plant cooperated in research, the process is as follows: furnace ash→iron capture reduction smelting→oxidation smelting→acid leaching→slag calcination→wet purification→platinum-palladium-ruthenium alloy powder. The direct yield of Pt, Pb and Rh was 83%, the total yield was 98%, and the product purity was 99.9%. The recycling process of the old platinum net is simple, and the waste net is dissolved, purified, reduced, and then the drawn wire mesh is woven, and the recovery rate is >99%. [2] Recycling of glass fiber industrial platinum Kunming Institute of Precious Metals proposed that the Pt, Rh, and Au alloy wastes will be deeply decomposed with aqua regia, the sodium salt will be turned, the hydrogen will be reduced by hydrogen peroxide, the impurities will be removed by ion exchange, and the hydrazine will be reduced. Pure Pt, Rh. The platinum rhodium product has a purity of 99% and a recovery of 99%. The Institute of Material Recycling and Utilization has proposed a process for recovering platinum ruthenium from waste refractory bricks and glass slag by using "dolomite-soda ash mixed sintering method". The waste refractory bricks are ball milled, melted, water-crushed, acid-soluble, filtered, and the filter residue is dissolved in aqua regia, and the nitrate is exchanged, and the hydrated hydrazine is reduced to obtain a platinum ruthenium product. The total yield of platinum rhodium is >99%, and the purity of the product is 99.95%. The institute combined with years of production practice to propose the combination of metallurgy and metallurgy to recover platinum ruthenium in waste refractory bricks, which reduces the cost, shortens the process and receives better results. [3] Recovering platinum and palladium from spent catalyst, dissolving precious metal method, Kunming Precious Metal Research Institute and Shanghai Petrochemical General Plant adopt high temperature roasting, hydrochloric acid plus oxidation leaching, zinc powder replacement, hydrochloric acid plus oxidant dissolution, solid ammonium chloride sinking Platinum, calcined to pure platinum, the product platinum purity of 99.9%, the recovery rate of 97.8%. Has applied for a Chinese patent. Second, the Institute of Materials Recycling and the Ministry of Nuclear Industry cooperated with the “all-melting method†for leaching, and the ion exchange adsorbed platinum (or palladium). The recovery of platinum was >98%. The yield of palladium was >97%. Product purity is >99.95%. Has applied for a Chinese patent and is used in several factories. Third, the Institute of Materials Recycling and Yangzi Petrochemical Co., Ltd. cooperated to study the recovery of palladium from spent palladium carbon catalyst. The spent catalyst is subjected to carbon burning, chlorination leaching, ammonia complexation, acidification and purification, and finally hydrazine hydrate reduction to obtain a purity of >99.95% sponge palladium, and a small amount of palladium in the waste liquid such as complex slag is adsorbed and recovered by the resin. The palladium recovery rate is >98%. Has applied for a Chinese patent. [4] Recycling of platinum and rhodium catalysts, the Institute of Materials Recycling and Co., Ltd. cooperated with Changling Refinery to adopt the method of “full dissolution†leaching, ion exchange adsorption of platinum rhodium, and precipitation agent to separate platinum rhodium. The platinum recovery rate is >98%, the ruthenium yield is >93%, the purity of the platinum ruthenium product is >99.95%, and the tail liquid aluminum sulfate can be used as the raw material for the production of catalyst. Second, Tsinghua University cooperates with Beijing Rare Metals Refinery. The platinum ruthenium in the spent catalyst is recovered by extraction. The spent catalyst is dissolved in 40% sulfuric acid, the hydrazine is extracted with 40% diisooctyl sulfoxide, the stripping solution produces potassium citrate, the sulfuric acid insoluble slag is burned to remove carbon, the acid is immersed in platinum, and the leaching platinum solution is 40%. The platinum is extracted by diisooctyl sulfoxide, and the counterplating solution is reduced by platinum. The extraction rate of platinum is >99%, the stripping rate is >99%, the platinum yield is >97%, the product platinum purity is 99.9%; the extraction rate of bismuth is >99%, and the rejection rate is >99%. [5] Separation and purification of platinum-ruthenium alloy by Kunming Institute of Precious Metals: The aluminum alloy for platinum-rhodium alloy is “broken, dilute hydrochloric acid with dilute hydrochloric acid to obtain fine platinum rhodium powder, dissolved with hydrochloric acid and oxidizing agent, and the solution is extracted with trialkylphosphine oxide to separate platinum.铑, ion exchange purification 铑. 铑 purity 99.99%, 铑 recovery rate 92~94%. Has applied for Chinese patent. Second, Chengdu 208 factory introduced a set of platinum bismuth separation equipment from Japan, platinum yield 98.5%, 铑 yield 95%, product purity of platinum and rhodium> 99.95. [6] was purified from osmium osmium iridium alloy scrap material recycling the China Corporation, East China branch combustion in oxygen separation using osmium iridium, osmium oxide, alkali absorption, precipitation of sodium sulfide, in addition to Sulphur is coarse, re-oxidized, hydrochloric acid is absorbed, ammonium chloride is precipitated, hydrogen is reduced, pure strontium powder is prepared, and the recovery rate of strontium is >98%. This method is suitable for waste containing 3% to 8% of strontium. [7] The recycling of niobium in the nib grinding waste is proposed by the East China Branch to recover the nib grinding waste containing 0.4%~1% of niobium by flotation. Sodium oleate is a flotation agent, and 2# oil is a foaming agent and an acidic medium. Concentrate containing 5%>5%, tailings containing 钌<0.2%, 钌 recovery rate>90%. [8] From spent catalyst slag The palladium and copper were recovered. The material recycling research institute used Hcl-H2O2 two-stage countercurrent leaching, and the xanthate precipitation and palladium and copper separation method recovered copper from the spent catalyst sludge containing Pd 0.8% and Cu 26.2%. Palladium. Recovery rate Pd>98%, Cu>95%[20]. Second, Shenyang Institute of Mining and Metallurgy uses dilute Hcl immersion copper, iron replacement copper, leaching slag oxidative roasting, rare king water leaching, zinc powder replacement, crude palladium Purified by dichlorodiamine palladium, the purity of palladium is 99.99%, the recovery is >98%, and the yield of copper is 92%.
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