Uranium slurry leaching

The effect of the degree of regeneration of the resin on the degree of extraction of a solute was measured by Slater using a seven stage unit. The results are shown in Fig. 39 for the extraction of uranium using a fluidized bed slurry of a strong base resin in a 10% uranium ore leach slurry. 

Extraction of Bertrandite. Bertrandite-containing tuff from the Spor Mountain deposits is wet milled to provide a thixotropic, pumpable slurry of below 840 p.m (—20 mesh) particles. This slurry is leached with sulfuric acid at temperatures near the boiling point. The resulting beryUium sulfate [13510-49-1] solution is separated from unreacted soflds by countercurrent decantation thickener operations. The solution contains 0.4—0.7 g/L Be, 4.7 g/L Al, 3—5 g/L Mg, and 1.5 g/L Fe, plus minor impurities including uranium [7440-61-1/, rare earths, zirconium [7440-67-7] titanium [7440-32-6] and zinc [7440-66-6]. Water conservation practices are essential in semiarid Utah, so the wash water introduced in the countercurrent decantation separation of beryUium solutions from soflds is utilized in the wet milling operation. 

Fig. 1. Schematic flowsheet of uranium processing (acid leach and ion exchange) operation. Numbers refer to the numbers that appear in the boxes on the flowsheet. Operations (3), (6), (9), and (11) may be done by thickening or filtration. Most often, thickeners are used, followed by filters. The pH of the leach slurry <4) is elevated to reduce its corrosive effect and to improve the ion-exchange operation on the uranium liquor subsequently separated, In tile ion exchange operation (7), resin contained in closed columns is alternately loaded with uranium and then eluted. The resin adsorbs the complex anions, such as UC fSO 4-. in which the uranium is present in the leach solution. Ammonium nitrate is nsed for elution, obtained by recycling the uranium filtrate liquor after pH adjustment. Iron adsoibed with the uranium is eluted with it. Iron separation operation (8) is needed inasmuch as the iron hydroxide slurry is heavily contaminated with calcium sulfate and coprecipitated uranium salts. Therefore, the slurry is recycled to the watering stage (3). Washed solids from 1,6). the waste barren liquor from (7), and the uranium filtrate from (11) are combined. The pH is elevated to 7.5 by adding lime slurry before the mixture is pumped to the tailings disposal area. (Rio Algom Mines Limited, Toronto)...

The early experiments on solvent extraction directly from leached pulp were beset with problems such as losses of solvent in the aqueous phase and the formation of emulsions. The use of mixer-settler, pump mixer, and internal mixer-settler type contactors on a laboratory scale (Gil) has demonstrated the feasibility of uranium extraction from desanded slurries with 5-1. )% solids and from high-density slurries with 48-60% percent solids. The deemulsification rate of a synthetic slurry as a function of the temperature of the system and the pH of the slurries (T12) and the effect of extractant entrainment in the aqueous effluent on solvent extraction of uranium from slurries containing more than 40% solids (E6) have been studied. 

North and Wells (N7) described the design and operation of a rotary-film contactor for the solvent extraction of metals directly from leached ore slurries. It consists of an enclosed rotating assembly of closely spaced disks centrally mounted on a common horizontal shaft. The transfer of the metal to the solvent layer is effected by the rotating disks where a film of slurry is formed on contact with the leached ore at the bottom of the vessel. This contactor gave excellent uranium recovery from sulfuric... 

Leaching and Extraction of Mineral Values from High Concentration of Solids A uranium plant had 10 large slurry tanks for leaching and extraction (approximately 14 m in diameter and 14 m high). They had about 14,000-m capacity. 

Precipitation of uranium from duate. In the Dawn mill, uranium was recovered from eluate by two-stage precipitation with alkali. In the first stage, pH is increased to 3.3 to 3.6 by addition of CaO slurry. This precipitates most of the ferric iron that may have been adsorbed with the uranium and removes most of the sulfate as CaS04. Because the filter cake contains 1 to 2 percent uranium, it is returned to the leaching circuit. 

Uranium ore is typically mined or leached in situ. For the mined ore, the raw material is milled to produce a high surface area slurry, which is then treated with H2SO4. The sulfuric acid oxidizes the uranium to the soluble hexavalent state. The addition of base to the solution precipitates an oxide of uranium known as yellowcake , UsOs. A similar process is used for the in situ leaching of uranium ore except that the initial treatment is performed on bores with a slightly acidic and high oxygenated aqueous solution that is raised to the surface and allowed to go through an extraction process to remove the uranium. 

Grinstead, R. R. et al. Solvent extraction of uranium from add leach slurries and solutions. Proc. Is/ Int. Conf. on the Peaceful Uses of Atomic Energy, Geneva, 1955, Paper 523. 

At the mill, usually located close to the mine, the ore is crushed and ground to a fine slurry. Sulfuric acid, in which uranium is soluble, is used to leach the product from the bulk material. The residue, consisting of undissolved solids (waste rock) is referred to as the tailings. This material contains most of the radioactivity including radium and toxic materials such as heavy... 

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