any copper solvent extraction process involving sulfuric acid leaching followed by copper solvent extraction with LIX® Reagents. The Isocalc® program will generate extraction and stripping isotherms and construct McCabe-Thiele diagrams for a large nu
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Abstract. A simultaneous distillation-solvent extraction (SDE) procedure was evaluated for the recovery of volatile compo nents from pasteurized orange juice. The Godefroot semi-micro SDE apparatus with methylene chloride solvent was used and extract
Accelerated solvent extraction (ASE), also referred to as pressurized fluid extrac-tion (PFE) and pressurized liquid extraction (PLE), is a liquid solvent extraction technique that uses aqueous and organic extraction solvents at elevated tempera-ture
end, this study evaluated the efficacy of three techniques (accelerated solvent extraction [ASE], Soxhlet and so- nication) for the extraction of a large suite of synthetic and natural estrogens, androgens and progestogens, as
Solvent Extraction of Radionuclides from Aqueous Tank Waste Peter V. Bonnesen, Richard A. Sachleben, and Bruce A. Moyer, Oak Ridge National Laboratory Task Description The purpose of this task is to develop an efficient solvent-extraction and strippi
extraction process. The result is faster extraction times and a significant reduction in solvent use. Many of the organic solvents used in extractions boil at relatively low temperatures. This is a limitation to techniques such as Soxhlet or automate
the solvent extraction technique for metals separation before base metals recovery was implemented in the late 1960s, when the first large copper plants came into operation. A number of extractants have been used for uranium extraction from acid solu
sample in conjunction with the amine solvent to create a single phase extraction medium which is a homogenous mixture of TEA and the water and oils that were present in the sample. Where extraction efficiencies of other solvent extraction systems are
Extraction Stripping LO BO PLS LE Raff RE Fig. 1. General flow diagram of the copper solvent extraction process. The copper transfer between the aqueous and organic phases takes place in mixers and the phases are separated in settlers. The equipment
Uranium Solvent Extraction
BASF technology for the recovery of uranium from acid leach solutions History
The Mining Solutions unit of BASF (formerly Cognis) has been intimately involved in uranium processing technology since 1957. That was when we introduced A lamine® 336 to the mining industry as the first commercially available tertiary amine solvent extraction (SX) reagent for the recovery and concentration of uranium.
Uranium production slowed considerably after the Three Mile Island (1979) and Chernobyl (1986) disasters. Both events brought nuclear power into disfavor and severely reduced the demand for uranium. The use of uranium from spent nuclear arms to produce energy as fuel further limited the mining and processing of the mineral.
Prior to 1957, ion exchange (IX) was the accepted route for the recovery of uranium from acid leach solutions. With Alamine® 336 vastly improving the solvent extraction process, BASF reagents now offered the advantages of reduced costs, reduced use of nitrates and chlorides, and the capacity to produce a high-purity uranium product.
During these unfavorable times, many companies within the industry lost a vast amount of know-how as experienced engineers and metallurgists, associated with the expansionist years of the 1950s through the early 1980s, either retired or moved into other industries.
The proven advantages of the Alamine® 336 SX process caused many operations to combine SX with their existing Ion Exchange (IX) processes by adding an SX circuit following IX – flow sheets known as ELUEX or BUFFLEX. Other plants made a complete conversion to the Alamine® 336 SX flow sheet and the majority of the new uranium projects installed SX c apacity and no IX. By the end of the 1970s, eighty percent of the USA’s uranium production – then the largest producer – used the BASF Alamine® 336 SX process and flow sheet.
BASF has a variety of reagent technologies that can reduce or eliminate problems in the uranium recovery process. Contact us to discuss your particular situation.
Understanding the eventual value and importance of nuclear power, BASF maintained its commitment to optimizing uranium recovery and retained its core expertise in uranium SX technology.
Reactions most commonly found in uranium processing
Today, the future of the uranium industry looks favorable, with an expected increase of uranium needed to meet energy demand. Uranium inventories are at manageable levels and the pressure to create low-cost, high-purity stockpiles is increasing. BASF is committed to supporting the growing demands of the industry and maintaining its leadership role in uranium SX technology.
MSP® Minesite Services Program BASF provides uranium SX technical expertise through its MSP® Minesite Services Program. Our specialized program can help you address specific technical issues, reduce costs and improve the rate of recovery and concentration of uranium. This support is available through all BASF Mining Solutions offices worldwide.
Leaching of uranium minerals, accomplished in the hexavalent state, is enhanced by ferric oxidation. An oxidant, such as manganese dioxide, sodium perchlorate or hydrogen peroxide, is employed to convert ferrous iron to ferric iron. In the SX circuit, the clarified leach solution comes into contact with the organic phase comprising Alamine® 336, a longchain alcohol employed as a solvation modifier, and a suitable diluent. Often, the organic phase comes into contact with an acidified aqueous solution that preloads the amine with sulphate or bisulphate anions to enhance selectivity for uranium in the succeeding extraction stage. During extraction, uranyl sulphate is extracted into the o rganic phase by the amine in exchange for the sulphate anion. Since uranium extraction is an anion exchange process, other anions may also extract into the organic phase. To prevent these anions from transferring to the final product as impurities, several scrubbing stages may be employed using, for example, acidified water, followed by aqueous ammonia. Further additions of ammonia are employed to strip uranyl sulphate from the organic phase as the pH value is gradually increased, while taking care not to precipitate uranium salts. Finally, uranium is often precipitated as ammonium diuranate (ADU) which, after drying, is calcined to produce high purity uranium oxide, frequently greater than 99 % pure.
COMMON CHEMISTRY FOR THE PROCESSING OF URANIUM LEACHING
U0 2 + Fe 3+ U0 22+ + Fe2+ (acid soluble) U0 22+ + H 2 S04 UO 2 S04
Technical challenges Molybdenum “impurities” Molybdenum and, to a lesser extent, vanadium are co-extracted with uranium. Both will report as impurities unless suitable changes in the chemistry of the system are employed. Molybdenum, in particular, can cause significant emulsion problems – the so-called blue or green goo – depending upon the relative concentration of molybdenum and Alamine reagent, the type of Alamine reagent, and the oxidation state of the molybdenum present. BASF solved this potential problem by developing Alamine® 304 for leach solutions in which molybdenum is present in higher concentrations. Carbonaceous material Carbonaceous material, such as humates, fulvates or man-made organic compounds, can load onto amines, slowly “poisoning” the organic phase to the point that it will no longer extract uranium. BASF has developed techniques for reagent / solvent regeneration to reduce or eliminate this potential problem.
Silica levels Soluble silica is produced in the leaching stage. High levels of silica ( > 500 ppm) will cause problems with phase separation, stable emulsion formation and crud formation. Control is achieved through the use of suitable coagulants and preferred mixing continuities. BASF has developed technology to help you choose flocculants and coagulants compatible with the SX process. Oxidation /nitration At high oxidation potential levels, particularly when nitrates are present, amine or diluent may be degraded. Precautionary techniques have been developed for such extreme cases.
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