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Carbonate leaching

Carbonate leaching under ambient conditions is extremely slow with poor recoveries. Therefore, the ore is typically leached in an autoclave with air providing most of the needed oxygen. The leach Hquor is separated from the soHd in a countercurrent—decantation system of thickeners, and the uranium is precipitated from the clarified sodium carbonate solution with addition of sodium hydroxide (eq. 9) (23). [Pg.317]

Solvent Extraction. Solvent extraction has widespread appHcation for uranium recovery from ores. In contrast to ion exchange, which is a batch process, solvent extraction can be operated in a continuous countercurrent-fiow manner. However, solvent extraction has a large disadvantage, owing to incomplete phase separation because of solubihty and the formation of emulsions. These effects, as well as solvent losses, result in financial losses and a potential pollution problem inherent in the disposal of spent leach solutions. For leach solutions with a concentration greater than 1 g U/L, solvent extraction is preferred. For low grade solutions with <1 g U/L and carbonate leach solutions, ion exchange is preferred (23). Solvent extraction has not proven economically useful for carbonate solutions. [Pg.317]

Chemical Precipitation. The product of the extraction processes, whether derived from acid or carbonate leach, is a purified uranium solution that may or may not have been upgraded by ion exchange or solvent extraction. The uranium ia such a solution is concentrated by precipitation and must be dried before shipment. Solutions resulting from carbonate leaching are usually precipitated directly from clarified leach Hquors with caustic soda without a concentration step, as shown ia equation 9. [Pg.318]

Laterite Reduction roasting 2 NiO + C —> 2 Ni + C02 Ammonia-ammonium carbonate leaching in the presence of oxygen... [Pg.478]

Alkaline leaching is carried out by using sodium carbonate solution. In this case any U(IV) present in the ore must also be oxidized to U(VI). The uranium species soluble in carbonate leach solutions in the uranyl tricarbonate ion. The formation of this ion by solubilization of a hexavalent uranium mineral such as camotite, or a tetravalent uranium mineral such as uraninite, may be represented by the following reactions ... [Pg.547]

Carbonated soft drinks (CSDs), estimated maximum oxygen tolerance, 3 38 It Carbonated soft drink bottles, 20 45-46 world market for, 20 53-54 Carbonate leaching, of uranium ores,... [Pg.140]

Some years ago a hydrometallurgical route, called the AmMAR concept, was presented [24], The concept (Fig. 14.15) represented a general processing route for a wide variety of feed materials. The detailed design of each specific process involved a specific number of known chemical operations, combined in unique ways. The main thread was the ammonia ammonium chloride or carbonate leach solution and its extraordinary chemical flexibility. [Pg.633]

In this process [27], the metals are extracted successively by the same extractant, employing suitable pH values for each metal. The spent catalyst is first roasted in an air stream at 300°C to remove oil and sulfur deposited on the surface of the catalyst. Then the metals are dissolved in an ammonium carbonate leach liquor at 80°C. Finally, the three metals are isolated and purified from one another using solvent extraction with an alkylmono-thiophosphoric acid (MTPA) with a structure similar to DEHPA. The following flow sheet was suggested (Fig. 14.19) ... [Pg.641]

The Determination of Boron. After dry ashing in the manner used in the lithium, beryllium, etc., procedure, the ash is fused with sodium carbonate, leached in water, and acidified with sulfuric acid. The colorimetric carminic acid method is then used to determine the boron. [Pg.39]

Reductive dissolution carbonate leaching of arsenic from sulfides... [Pg.154]

Fig. 21.12. Uranium ore mill processes (A) carbonate leach, caustic precipitation process (B) acid leach, ion exchange and acid leach, solvent extraction processes (C) acid leach, resin-in-pulp process. Fig. 21.12. Uranium ore mill processes (A) carbonate leach, caustic precipitation process (B) acid leach, ion exchange and acid leach, solvent extraction processes (C) acid leach, resin-in-pulp process.
The name potash derives from an early production method in which potassium carbonate, leached from wood ashes, was crystallized by evaporating the leachate in large iron pots. The salt potassium chloride (muriate of potash or KC1) is now the major source of the element (95%) other important salts are potassium sulfate (sulfate of potash, K2S04), potassium magnesium sulfates of varying K/Mg ratios, and potassium nitrate (KN03). [Pg.1135]

Uranyl carbonate complexes have attracted considerable interest in recent years as they are intermediates in the processing of mixed oxide reactor fuels and in extraction of uranium from certain ores using carbonate leaching more topically they can be formed when uranyl ores react with carbonate or bicarbonate ions underground, and can be present in relatively high amounts in groundwaters. The main complex formed in carbonate leaching of uranyl ores is 8 coordinate [1102(003)3], but around pH 6 a cyclic trimer [(002)3(003)6] has been identified. [Pg.178]

Other factors also affect the mobility of uranium in soil. A field study performed near an active carbonate leach uranium mill showed that uranium in an alkali matrix can migrate to the groundwater (Dreesen et al. 1982). Uranium mobility may also be increased due to the formation of soluble complexes with chelating agents produced by microorganisms in the soil (Premuzie et al. 1995). [Pg.288]


See other pages where Carbonate leaching is mentioned: [Pg.317]    [Pg.318]    [Pg.98]    [Pg.76]    [Pg.486]    [Pg.492]    [Pg.506]    [Pg.546]    [Pg.548]    [Pg.152]    [Pg.898]    [Pg.912]    [Pg.62]    [Pg.62]    [Pg.317]    [Pg.318]    [Pg.962]    [Pg.962]    [Pg.255]    [Pg.5]    [Pg.14]    [Pg.15]    [Pg.27]    [Pg.39]    [Pg.898]    [Pg.912]    [Pg.279]    [Pg.280]    [Pg.917]    [Pg.37]   


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