Ammonia leaching

after a good deal of complicated aqueous chemistry, we have separated Cu, Ni, and Co ions from one another. Reduction of the ions to the metals is described in Section 17.6. A more recent version of the ammonia leach process uses an ammonia/ammonium carbonate, rather than sulfate, buffer solution. 

---

For operations producing 30,000 tons or less of copper annuaHy, hydrometaHurgy offers an alternative to smelting that avoids problems associated with sulfur dioxide recovery and environmental controls. Techniques include the Anaconda oxygen—ammonia leaching process, the Lake Shore roast-leach-electrowin process, and ferric chloride leaching processes for the treatment of copper sulfides. AH the facHities that use these techniques encountered serious technical problems and were shut down within a few years of start-up. 

Nevertheless, manganese nodules can, at best, be considered to be similar to land-based nickel laterites, and consequently most of the processing techniques that have been tried are similar to those used on lateritic ores. Reduction roasting followed by ammonia leaching, as in the Nicaro process, and high-temperature sulfuric acid leaching, as in the Moa Bay operation, have been extensively tried to process nodules. 

Duyvesteyn, W. P. C. Sabacky, B. J. Ammonia Leaching Process for Escondida Copper Concentrates (Reprinted from Extractive Metallurgy of Copper, Nickel, and Cobalt. Vol. 1, 1993). Trans. Inst. Min. Metall. Sect. C-Miner. Process. Extr. Metall. 1995, 104, C125-C140. 

Campbell, I. Cupertino, D. C. Emeleus, L. C. Harris, S. G. Owens, S. Parsons, S. Swart, R. M. Tasker, P. A. Tinkler, O. S. White, D. J. Diazopyrazolones as solvent extractants for copper from ammonia leach solutions. International Solvent Extraction Conference, Cape Town, South Africa, Mar. 17-21, 2002, 347-352. 

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. 

The ammonia leach leaves the iron as an insoluble residue that is removed by filtration. The filtrate is contacted with a ketoxime reagent (e.g., LIX84I, Cognis) to extract the nickel [14]. 

An alternative route to cobalt/nickel separation following ammonia leaching in the Caron process is to produce a mixed Co/Ni carbonate product. This can then be dissolved in sulfate media and processed using one of the acidic extractants described later [13]. 

Trace the steps in the production of high purity nickel metal from crude sulfide ore (a) by the Sherritt Gordon ammonia leach process, (6) by the Mond process, and (c) by acid leaching. 

Hydrometallurgical treatment of lateritic ores, by the reduction roast/ammonia leach process is one of the methods used for the recovery of nickel from low grade lateritic ores. In a recent study Chander and his associates (19, 20) used such... 

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. 

Fig. 2. Ammonia leach and preferential hydrogen reduction for a nickel-copper matte. Pearce et al. (P3).

Caron Process reduction roast - ammonia leach)... 

X. Meng, K. Han, The principles and applications of ammonia leaching of metals . Mineral Processing and Extractive Metallurgy Review, 16 (1) (1996), pp. 23-61. 

K. Osseo-Asare, and D. Fuerstenau, Adsorption losses in ammonia leaching of copper, nickel and cobalt from deep-sea manganese nodules . Complex Metall. 78, (Proceedings Inti. Symposium, Bad Harzburg, Germany), M. Jones (Editor), IMM, London, 1978, pp. 42 7. 

The direct reductive acid leaching process was developed by Hindustan Zinc Limited, Udaipur. Starch was used in the process as reductant during leaching. The separation process is based on selective sulphide precipitation followed by solvent extraction and electrolysis. The other two processes are based on ammonia leaching, developed at the Institute of Materials and Minerals Technology, Bhubaneshawar (IMMT-B) and National Metallurgical Laboratory,... 

---