Ammonia leach liquors

Copper Recovery from Ammonia Leach Liquors.154... 

Kumar, V. Jana, R. K. Pandey, B. D. Jha, D. Nayak, A. K. Bagchi, D. Akerkar, D. D. Recovery of copper, nickel and cobalt from ammoniacal leach liquors obtained by direct ammonia leaching of sea nodules. Trans. Indian Inst. Met. 1987, 40, 64-70. 

Vanadium usually is recovered from its ores by one of two processes, (1) leaching raw mineral with hot dilute sulfuric acid, and (2) roasting ore with common salt to convert vanadium into water soluble sodium vanadates. In the sulfuric acid leaching process, vanadium is extracted from acid leach liquors by solvent extraction with an aliphatic amine or an alkyl phosphoric acid in kerosene. The organic solvent extract then is treated with an aqueous solution of ammonia in the presence of ammonium chloride to convert vanadium into ammonium metavanadate. Alternatively, the organic extract is treated with dilute sulfuric acid or an aqueous solution of soda ash under controlled conditions of pH. Vanadium is precipitated from this solution as a red cake of sodium polyvanadate. 

Acidification of the leach liquor with sulfuric acid produces solutions containing Mog0264-, which is extracted into a solution of tertiary amine hydrogen sulfate as described previously. Loaded organic phases are stripped with aqueous ammonia to give solutions from which ammonium paramolybdate can subsequently be crystallized ... 

For direct precipitation of vanadium from the salt-roast leach liquor, acidulation to ca pH 1 without the addition of ammonia salts yields an impure vanadic acid when ammonium salts are added, ammonium polyvanadate precipitates. The impure vanadic acid ordinarily is redissolved in sodium carbonate solution, and ammonium metavanadate precipitates upon addition of ammonium salts. Fusion of the directly precipitated ammonium salts can yield high purity V2Os for the chemical industry. Amine solvent extraction is sometimes used to recover 1—3 g/L of residual V2Os from the directly precipitated tail liquors. 

Copper sulphate and ammonia, added to the sodium carbonate leach liquor, have been found to catalyse the oxidation by air where this is necessary. This process has been used in the large pilot plant at Grand Juntion in the United States. ... 

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). 

The leach liquors are then poured through ion-exchanger beds or columns. The resins employed for these processes are typically of the sulfonate variety. Uranium is removed from the resin by elution with solutions containing high concentrations of chloride or nitrate ions after which the uranium is recovered by precipitation through addition of ammonia. 

Losses are kept to a minimum by carbonation of the mother liquor with C02 and recycle of the carbonated product back to the leach system. From acid solutions, uranium is usually precipitated by neutralization with ammonia or magnesia. Ammonia gives an acceptable precipitate, for which compositions such as (NH4)2(U02)2S04(0H)4 H20 were calculated. The ammonium salt is preferred if the product is to be used in the manufacture of... 

Sherritt ammonia pressure leaching. This hydrometallurgical process was first implemented in 1954 by Sherritt Gordon Mines in Fort Saskatchewan, Alberta, Canada. In this process, the finely ground nickel sulfide concentrates obtained after flotation or the metal matte are reacted at 80 to 95°C in a high-pressure autoclave under 850 kPa with an oxygenated ammonia or ammonia-ammonium sulfate liquor. Ammonia dissolves nickel and, to a lesser extent, cobalt, zinc, and copper by forming soluble ammonia complex cations as follows ... 

Note that despite having the same deep-blue coloration, Schweitzer s liquor, usually obtained by leaching oxidized copper turnings by a concentrated ammonia solution, is different from celestial water, which is obtained by dissolving freshly precipitated copper (II) hydroxide from a copper-sulfate solution by adding an excess of concentrated ammonia. In both cases, the ammonia forms a stable tetraamino copper (Il)cation [Cu(NHj)/ ], but in the first case it consists of the solution of Cu(NH,)/, 20H", while in the celestial water it consists of the sulfate salt Cu(NHj)/, SO/. ... 

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