Cobalt acid pressure leaching

Chalkley, M. E. Toirac, I. L. The acid pressure leach process for nickel and cobalt laterite. Part I review of operations at Moa. Hydrometallurgy and Refining of Nickel and Cohalt, Annual Hydrometallurgy Meeting of CIM, 27th, Sudbury, Ont., Aug. 17-20, 1997, 341-353. 

The following conclusions can be drawn from the precipitation studies of nickel and cobalt from a copper depleted Cu-Ni-Co sulphate solution generated from acid pressure leaching of a synthetic matte containing Cu-Ni-Co-Fe-S ... 

Cobalt can be recovered from nickel-sulfide concentrates or nickel matte by the Sherritt-Gordon ammonia leaching process in Fort Saskatchewan, Alberta, Canada, and it is also recovered from sulfuric-acid pressure leaching of laterites. In both cases, cobalt is obtained in nickel-free liquor by reduction with hydrogen under elevated pressure and temperature (Section 2.2). 

Soldenhoff, K., Hayward, N., and Wilkins, D. 1998. Direct solvent extraction of cobalt and nickel from laterite-acid pressure leach liquors. In EPD Congress 1998, ed. B. Mishra, 153-165. Warrendale, PA The Minerals, Metals and Materials Society. 

Nickel and cobalt are recovered by processes that employ both pressure leaching and precipitation steps. The raw materials for these processes can be sulfide concentrates, matte, arsenide concentrates, and precipitated sulfides. Typically, acidic conditions are used for leaching however, ammonia is also effective in leach solutions because of the tendency for soluble cobalt and nickel ammines to form under the leach conditions. 

The Sumitomo Metal Mining Co. in Japan uses a carboxylic acid extractant to recover nickel and cobalt from a solution obtained from the pressure leaching of metal sulfide concentrates with sulfuric acid.44 Iron, copper, zinc and manganese are removed from the leach liquor by conventional precipitation methods prior to the extraction of nickel and cobalt into a 40-60% solution... 

The application of ammonia pressure leaching as a method of refining nickel-cobalt matte has been studied (Bll, P3) and is considered an economically attractive process. Nickel-copper mattes with low cobalt content have been found to be readily leached with ammonia (P3). A high-nickel matte with a composition of 77% Ni, 0.1% Cu, 1.8% Co, 0.7% Fe, and 20% S is amenable to both acid and ammonia leach, but the sulfur deficiency can be made up more economically by circulation of ammonium sulfate solution within the process than by providing the sulfur through addition of sulfuric acid. 

Cobalt is produced as a coproduct of nickel or copper refining. Copper-cobalt sulfide concentrates can be processed by the RLE process. Mixed cobalt-nickel sulfides can be precipitated from ammoniacal leach solutions and as mixed nickel-cobalt hydroxide or carbonate from acid sulfate leach processes. From chloride leach solutions, cobalt can be separated by solvent extraction. Most cobalt production is associated with nickel production from sulfide and laterite ores. Pressure leaching, solvent extraction followed by the electrowinning of... 

E.T. Carlson, C.S. Simons, Pressure Leaching of Nickeliferous Laterites with Sulfuric Acid, Extractive Metallurgy of Copper, Nickel, and Cobalt, P.E. Queneau ed.. Interscience Publishers, New York, (1961), 363-396. 

The high-grade matte from the converter process or the flash melting process contains sulfur and some amounts of copper, cobalt and iron and, in addition, traces of noble metals. Refined nickel is produced by a variety of methods and is delivered as nickel cathodes or nickel powder. The latter are produced partly by carbonyl processes, partly by hydrogen reduction in conjunction with pressure leaching processes. In the latter, matte is leached under pressure with acid or ammonia, and nickel is recovered as a powder by reduction with hydrogen under pressure. 

In the acid-leaching process, the oxide ore is leached with sulfuric acid at elevated temperature and pressure, which causes nickel, but not iron, to enter into solution. The leach solution is purified, foHowed by reaction with hydrogen sulfide and subsequent precipitation of nickel and cobalt sulfides. 

Pressure-acid leaching was used to extract cobalt from Blackbird mine ores before its closing in 1974. The result was a very fine cobalt powder which was subjected to a seeding process to produce cobalt granules. Leaching methods are also used in the refinement of lateritic ores. 

Kyle, J. H. Pressure acid leaching of Australian nickel/cobalt laterites. Publ. Australas. Inst. Min. and Metall. 1996, 6/ 96, 245-250. 

Acid leaching is usually carried out using sulfuric acid under pressure to dissolve the majority of the iron minerals and to release the cobalt and nickel. If this is carried out at 150-250°C, then the iron(III) is precipitated as haematite or jarosite, reducing the amount of iron in the leachate. The... 

In the Nippon Mining Company process,163 the aqueous feed consists of a solution of cobalt, nickel and other metal sulfates obtained by the high-pressure oxidative leaching of a mixed metal sulfide ore. Following the removal of iron and copper by chemical precipitation methods, and the successive extraction of zinc and cobalt by organophosphorus acid reagents (Section 63.3.2.2) under weakly acidic conditions, the pH value of the solution is adjusted to between 9 and 9.5 with ammonia, and nickel is extracted into a 25% solution of LIX 64N in an alkane solvent. 

The extraction of cobalt from arsenical concentrates consisting of autooxidation acid leaching under pressure, separation, purification, hydrogen reduction of ammoniacal leach solution, and removal of sulfur and granulation of the metal was described by Mitchell (M37). The final product contained 95.6% cobalt, 3.90% nickel, and 0.03% arsenic compared to the feed concentrate with an assay of 17.5% cobalt, 1% nickel, and 24% arsenic. 

The selective leaching of the nickel and cobalt from the gangue material is carried out in Pachuca-type leaching vessels with 98% sulfuric acid at temperatures between 450 and 500°F and with equivalent pressures between 400 and 600 psi. A typical leach liquor contains 6 gm/liter Ni, 0.6 gm/liter Co, 0.6 gm/liter Fe, 2.3 gm/liter Al, and 67 gm/liter SO4. Each batch is leached for about 90 min to extract 95% of the metal values. Preheating and heating of the ore slurry is by direct steam absorption in the reaction vessel. The barren residue is separated from the leach liquor by countercurrent decantation to a density of 55-60% solids. The solids are washed with very little dilution and about 99.5% of the soluble value are recovered. 

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