Leach liquor

Uranium Extraction from Ore Leach Liquors. Liquid—Hquid extraction is used as an alternative or as a sequel to ion exchange in the selective removal of uranium [7440-61-1] from ore leach Hquors (7,265,271). These Hquors differ from reprocessing feeds in that they are relatively dilute in uranium and only slightly radioactive, and contain sulfuric acid rather than nitric acid. 

Another example of a cost-effective liquid-liquid extraction process is the one used for recoveiw of uranium from ore leach liquors (Fig. 15-3). In this case the solvents, alkyl phosphates in kerosine, are recovered by liquid-liquid extraclion using a strip solution, and the... 

Ryon, Daley, and Lowrie [Chem. Eng. Ftog., 55(10), 70, (1959), U.S. AFC ORNL-2951, I960]. Continuous extraction of uranium from sulfate-ore-leach liquors and kerosine -t- trihiityl phosphate and di(2-ethylhexyl)-phosphoric acid baffled vessels, turbine agitated. There is strong evidence of the influence of a slow chemical reaction. 

TABLE 15-6 Settling of Aqueous Uranium Leach Liquors with Kerosine-Alkyl Phosphate Solvent ... 

High-speed agitators These are suitable for leaching reactions that are limited by diffusion in the leach liquor. An agitator of this type requires a propeller or a turbine to provide high-speed agitation... 

Sodium ferric fluoride is obtained as a byproduct in the solution processing of Na2BeF6 leach liquor. It is used for substituting for sodium silicofluoride (to an extent of up to 60%) in the ore fusion reaction. 

The separation of solids from liquids forms an important part of almost all front-end and back-end operations in hydrometallurgy. This is due to several reasons, including removal of the gangue or unleached fraction from the leached liquor the need for clarified liquors for ion exchange, solvent extraction, precipitation or other appropriate processing and the post-precipitation or post-crystallization recovery of valuable solids. Solid-liquid separation is influenced by many factors such as the concentration of the suspended solids the particle size distribution the composition the strength and clarity of the leach liquor and the methods of precipitation used. Some important points of the common methods of solid-liquid separation have been dealt with in Chapter 2. 

The feed should be free of clay materials, as they make separation of leach liquor from the treated solids difficult. 

The process making use of adsorption on carbon involves first contacting a pregnant leach liquor with the adsorbent (activated carbon) and then stripping the species adsorbed on it. Activated carbon is a widely recognized as a metallurgical reagent that has found a number of industrial applications. 

The chlorides of most metals have a very good water solubility, though there are exceptions in the case of some metals. A typical example of the latter is silver which can be very efficiently separated by forming insoluble silver chlorides. Although, the separation of silver as the chloride is rarely used as a method for bulk precipitation, it is certainly useful for the removal of relatively small amounts of the metal when present as a minor constituent In the case of cuprous and cupric chlorides, the former has a low solubility in water hence, if the leach liquor contains cupric chloride, a suitable reducing agent such as sulfur dioxide can be introduced to convert cupric chloride to cuprous chloride so that precipitation occurs. 

The separation of impurities such as calcium, barium and radium can be effected by the precipitation of their sulfates. In the case of sulfuric acid leaching of uraninite ore, the leach liquor contains radium which is removed if barium chloride is added since barium sulfate acts as a carrier for radium sulfate. 

Purification of leach liquors - as an example, mention may be made of the removal of cadmium and thallium from a zinc sulfate solution. In this case it is very convenient to use metallic zinc as a cementing metal, since the zinc that enters into solution is recovered subsequently. 

K. R. Rawling, Commercial Solvent Extraction Plant Recovers Copper from Leach Liquors, World Min., p. 34, Dec. 1969. 

Pandey, B. D. Bagchi, D. Kumar, V. Co extraction—selective stripping for the recovery of nickel and copper from the leach liquor of ocean nodules. Can. J. Chem. Eng. 1994, 72, 631-636. 

Sole, K. C. Solvent extraction of copper from high concentration pressure acid leach liquors. International Solvent Extraction Conference, Cape Town, South Africa, Mar. 17-21, 2002, 1033-1038. 

Virnig, M. J. Mackenzie, J. M. W. Wolfe, G. A. Boley, B. D. Nickel laterite processing Recovery of nickel from ammoniacal leach liquors. Miner. Metall. Process. 2001, 18, 18-24. 

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. 

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. 

Grosse, A. C., Dicinoski, G. W., Shaw, M. J., Haddad, P. R. (2003). Leaching and recovery of gold using ammoniacal thiosulfate leach liquors (a review). Hydrometallurgy, 09(1-3), 1-21. doi 10.1016/S0304-386X(02)00169-X... 

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