Platinum group nickel anode mud extraction process

Nickel electrowinning anode sludge separated in the base metals and sulfur, platinum group metals platinum enrichment process outputs concentrate. Before the 1970s, the nickel refining method was crude nickel electrolytic refining or nickel sulfide electrolytic refining. In the electrolytic refining process, precious metals in the soluble anode remained in the anode slime and became the main raw material for extracting platinum group metals. However, nickel electrorefining has a long cycle and many materials, and the direct yield of platinum group metals is low, and the dispersion loss is large. The technology for extracting platinum group metals directly from high nickel bismuth and copper- nickel alloys is developing rapidly, after the 1970s. Nickel anode mud is no longer the main raw material for the extraction of platinum group metals.

Composition and treatment principle of nickel anode slime The composition and precious metal grade of nickel electrolytic anode mud vary greatly with the place of origin. The components are usually sulfur, nickel, copper and iron , and also contain carbon, silicate slag, etc. The grade of metal and gold and silver is only 0.01% to 10%. Among them, the anode slime yield of crude nickel electrorefining is small (2% to 5%), the precious metal enrichment ratio is high, the anode mud contains low sulfur (8% to 10%), and the copper-containing nickel is high (40% to 60%). It also contains silica and carbon (about 20% to 30%), and the grade of precious metals can reach 1% to 10%. The yield of anode slime of nickel sulfide electrolytic refining is large (about 25%), the degree of precious metal enrichment is low, the anode mud contains high sulfur (70%~96%), the copper-containing nickel is low (1%~15%), and the precious metal grade Only 0.01% to 1%. Therefore, the treatment of nickel anode mud needs to continuously separate non-precious metal components according to its composition and enrich the precious metal concentrate. The lower the grade of precious metal in the nickel anode mud, the longer the process of enriching the precious metal concentrate, and the more steps, the greater the dispersion loss of the precious metal. Trying to minimize the dispersion of precious metals is an important principle in selecting and formulating a nickel anode sludge treatment process. Nickel Sulfide Electrolytic Refining Anode Sludge Treatment The process of producing platinum group metal concentrate from nickel sulfide electrolytic refining anode mud by China Jinchuan Nonferrous Metals Co., Ltd. Mainly desulfurization replaced with filtered hot, the secondary electrolysis, roasting and sulfuric acid leaching of an aqueous solution of chloride, zinc powder, copper removal processes such as permutation slag composition.

The composition of the nickel anode mud (mass fraction w/%) is: element S 67-95, Ni 0.4-8, Cu 0.3-5.4, :Fe 0.5-3.3, gold and platinum group metals total 0.01; wherein Au 50-70 g/t , Pt 60 ~ 75g / t, Pd 25 ~ 35g / t, rhodium, iridium, osmium, platinum-ruthenium content of about 1/10 of palladium. The nickel anode mud is thoroughly washed to remove chlorides before the formal treatment, increasing the sulfur content and reducing the base metal content. Then, the high-pressure steam is used to heat the nickel anode mud to separate the molten elemental sulfur (see the desulfurization of the precious metal material) at a temperature of 413 to 418 K (above the sulfur melting point). After the filter cake is smelted at a temperature of 1473 to 1573K and the silicate slag is separated, the obtained copper nickel ruthenium is recast as an anode for secondary electrolysis (see enrichment of platinum group metals by electrolysis), and the precious metal grade of the secondary anode mud is 0.1. %~0.3%. The secondary anode mud is mixed with concentrated sulfuric acid at a ratio of 1:1 to sulphate and calcined at a temperature of 823 K. The calcined material is leached with 5% dilute sulfuric acid to leaching copper, nickel and iron sulfate. The grade of precious metal in the leaching residue is increased to 1 % to 5%. The precious metal in the slag is leached by hydrochloric acid and aqueous chlorine solution. The chlorination rate of gold, palladium and platinum is over 95%, and lanthanum, cerium and lanthanum are concentrated in the chlorinated slag. The chlorinated liquid is replaced by zinc powder, and the replacement slag is decoppered with a high-iron solution of sulfuric acid to obtain a precious metal concentrate containing 40% to 60% of gold, platinum and palladium. From raw material nickel anode mud to concentrate precious metal, it is enriched by 4500-6000 times. Because the precious metal grade in the raw material is too low, the enrichment process is long, the recovery rate of gold, platinum and palladium is only 80%-96%, and the recovery rates of lanthanum, cerium and lanthanum are also low.

Treatment of Crude Nickel Electrolytic Refining Anode Mud When the precious metal content of the crude nickel electrorefining anode slime is less than 0.1%, it can be enriched by secondary electrolysis, and then the platinum group metal concentrate is extracted from the secondary electrolysis anode mud. When the content of precious metal in the anode mud is high, the bismuth metal can be separated by sulphating roasting leaching (see the enrichment of platinum group metals by sulfuric acid method), the leaching and enrichment of platinum group metals by chlorine, and the leaching and enrichment of platinum group metals by chlorine. Group metal concentrate. The enrichment process is the same as the nickel sulfide electrolytic refining of the anode slime. Crude nickel electrolytic refining anode mud can also be combined with copper anode mud to extract precious metal concentrate.

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