Chlorides leaching

Nickel and Cobalt. Often present with copper in sulfuric acid leach Hquors are nickel [7440-02-0] and cobalt [7440-48-4]. Extraction using an organophosphoric acid such as D2EHPA at a moderate (3 to 4) pH can readily take out the nickel and cobalt together, leaving the copper in the aqueous phase, but the cobalt—nickel separation is more difficult (274). In the case of chloride leach Hquors, separation of cobalt from nickel is inherently simpler because cobalt, unlike nickel, has a strong tendency to form anionic chloro-complexes. Thus cobalt can be separated by amine extractants, provided the chloride content of the aqueous phase is carefully controUed. A successhil example of this approach is the Falcon-bridge process developed in Norway (274). 

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. 

Surface modification reactions are used to improve the wettability of glass surfaces by polar stationary phases and to Improve the extent of deactivation by sllylation" [138-146,166]. Miaaiuua procedures have been investigated but only a few are in use. Of these, the most important reactions are etching by hydrogen chloride, leaching with aqueous hydrochloric acid, formation of whiskers and solution deposition of a layer of solid particles. Because of the high purity and thinness of the... 

Figure 6 A simplified flowsheet and materials balance for the recovery of copper from sulfldic ores by chloride leaching, solvent extraction and electrowinning, using for example reagents such as 7.

The phenolic oxime reagents (Section 9.17.4.2) have also been used to recover copper from chloride leach solutions,156... 

Fletcher, A. W. Sudderth, R. B. Olafson, S. M. Combining sulfate electrowinning with chloride leaching. JOM-J. 

Rice, N. M. Gibson, R. W. Solvent extraction with Cyanex 301 and 302 for the upgrading of chloride leach liquors from lateritic nickel ores. Value Adding through Solvent Extraction, [Papers presented at ISEC 96], Melbourne, Mar. 19-23, 1996, 1, 715-720. 

Cuprex [Copper extraction] A process for extracting copper from sulfide ores, combining chloride leaching, electro-winning, and solvent extraction. Piloted by a consortium consisting of ICI, Nerco Minerals Company, and Tecnicas Reunidas. 

Alternatively, limestone may be used instead of sulfuric acid to recover lithium from spodumene. Such recovery processes, known as alkaline methods, involve heating the ore with a mixture of ground limestone and calcium sulfate or chloride to form lithium sulfate or chloride. Leaching the kiln discharge with water yields an aqueous solution of hthium sulfate or chloride. 

Chammas, G.A., J.L. Hutson, J.J. Hart, and J.M. DiTomaso (1997). Microscale variability of atrazine and chloride leaching under field conditions. Weed Technol., 11 98-104. 

Chloride leaching of copper sulfides has received a great deal of attention in past decades. The chloride processes have distinct advantages over sulfate-based processes. The chloride systems have faster kinetics, making atmospheric leaching... 

Processes that use chloride leaching, solvent extraction to sulfate solution, and electrowinning from sulfate solution. 

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... 

Derivation (1) Alkali or acid extraction from vanadium minerals. (2) By igniting ammonium metavanadate. (3) From concentrated ferrophosphorus slag by roasting with sodium chloride, leaching with water and purification by solvent extraction followed by precipitation and heating. 

Cymet s use of aqueous ferric chloride leaching solution has also been proven to work with chalcopyritic ores [52]. 

Dyson, J.S., and R.E. White. 1987. A comparison of the convective dispersion equation and transfer function model for predicting chloride leaching through undisturbed structured clay soil. J. Soil. Sci. 38 157-172. 

Atmospheric processes have also been studied. As examples, the FCL process (Ferric Chloride Leach) extensively investigated and developed by CANMET (2), and a nitrate-based process (3) could be cited. The ability of ferric ions to oxidise various sulphide minerals, in particular sphalerite, has been known for years, and this was the basis for the FCL process. One of the perceived difficulties of the FCL process is the use of a chloride medium, and there are several incentives to operate in a sulphate system, not the least of which is the fact that the sulphate system is extremely well established. 

W.J.S. Craigen and Canmet/MSL Staff, The CANMET Ferric Chloride Leach Process for the Treatment of Bulk Base Metal Sulphide Concentrates , MSL Division Report. MSL 89-67, June 1989. 

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