Prodeco, Inc.

Unc Recovery Corporation

Unc Reclamation

Alex Magdics

Ralph E Worthington

Donald B Stain

Sandra L Paris

Donald A Luke

Aqueous effluent solutions containing metal cations may be treated with an extractant comprising an organophosphinic acid, a di-2-ethylhexyl phosphoric acid and/or an aliphatic amine to selectively separate chromium, nickel, cobalt, copper and lead cations from the aqueous solution. Typical extraction techniques include liquid-liquid extraction employing either mixer settlers or columns, liquid membrane extraction and selective supported membrane extraction.

Selective removal of chromium, nickel, cobalt, copper and lead cations

A process is described for the recovery of uranium from wet-process phosphoric acid utilizing an alkyl pyrophosphoric extractant. The extractant also contains a modifier for retaining the alkyl pyrophosphoric acid in solution in an essentially water-immiscible organic diluent during stripping. After extracting the uranium from wet-process acid, the APPA extractant is treated with an oxidizing agent such as hydrogen peroxide and the uranium stripped into an alkaline stripping solution. The alkaline stripping solution is an aqueous solution of an alkali metal or ammonium carbonate or hydroxide. The barren extractant is recycled for contacting with fresh wet-process acid. The uranium and any ferric iron present is precipitated in the stripping solution. The uranium is dissolved in an aqueous solution such as an aqueous solution of ammonium uranyl tricarbonate (AUT), any precipitated ferric solids are separated from the solution, and the uranium is reprecipitated, separated, dried and calcined to a U.sub.3 O.sub.8 product.

Process for recovering uranium using an alkyl pyrophosphoric acid and

A process is described for the recovery or uranium from wet-process phosphoric acid utilizing an alkyl pyrophosphoric extractant. The extractant also contains a modifier for retaining the alkyl pyrophosphoric acid ester in solution in an essentially water-immiscible organic diluent during stripping. After extracting the uranium from wet-process acid, the APPA extractant is treated with an oxidizing agent such as hydrogen peroxide and the uranium stripped into an alkaline stripping solution. The alkaline stripping solution is an aqueous solution of an alkali metal or ammonium carbonate unsaturated in uranium. The barren extractant is recycled for contacting with fresh wet-process acid. Any ferric iron present is precipitated in the stripping solution and then separated from the solution. The uranium is precipitated, separated, dried and calcined to a U.sub.3 O.sub.8 product.

Potassium chloride and sulfuric acid are reacted in a recycled aqueous solution in the stoichiometric ratio required for potassium sulfate production. Hydrogen chloride produced by the reaction of the potassium chloride and sulfuric acid is evaporated in admixture with water or in anhdrous form. The resulting solution is cooled to crystallize a potassium sulfate salt, preferably potassium bisulfate. The potassium sulfate salt is separated from the mother liquor and the mother liquor is recycled to the reaction step. The potassium sulfate salt is dissolved in an aqueous solution and sequentially decomposed to produce potassium sulfate and a mother liquor rich in sulfuric acid. The mother liquor rich in sulfuric acid is concentrated and recycled to the reaction step.

Method for the production of potassium sulfate using sulfuric acid and

A process for producing K.sub.2 SO.sub.4 from potassium chloride salts, calcium sulfate salts and another sulfate source wherein syngenite is formed and then decomposed with mineral acid to produce crystalline K.sub.3 H(SO.sub.4).sub.2. The K.sub.3 H(SO.sub.4).sub.2 crystals are recrystallized to produce K.sub.2 SO.sub.4 crystals.

Process for producing K.sub.3 H(SO.sub.4).sub.2 crystals and potassium

Process for producing and decomposing syngenite

A process is described for the recovery of tetravalent uranium from wet-process phosphoric acid utilizing an alkyl pyrophosphoric acid extractant or the like. After extracting the tetravalent uranium from wet-process acid, iron is stripped from the pregnant extractant into an oxalic acid stripping solution and then the tetravalent uranium is stripped from the pregnant extractant into an oxalate stripping solution. The oxalate stripping solution is an aqueous solution of an alkali metal or ammonium oxalate. The barren extractant is recycled for contacting with fresh wet-process acid. The uranium is oxidized and then precipitated in the oxalate stripping solution. The precipitated solids are separated from the solution, and the uranium is dried to a UO.sub.3 product.

Process for stripping uranium from an alkyl pyrophosphoric acid

Uranium in wet-process phosphoric acid in the tetravalent state is extracted with an alkylphenyl acid phosphate extractant comprising a mixture of mono- and di(alkylphenyl) esters of orthophosphoric acid. The pregnant extractant is stripped with a suitable stripping solution, and the barren extractant recycled to the extractant step. At least a portion of the recycled extractant is treated with concentrated sulphuric acid to remove organic and inorganic impurities including alkylphenol present in the barren extractant as a result of hydrolysis from the mixture of mono- and di-(alkylphenyl) esters of orthophosphoric acid to regenerate the extractant.

Concentrated sulphuric acid treatment of an alkylphenyl acid phosphate

Uranium in wet-process phosphoric acid in the tetravalent state is extracted with an alkylphenyl acid phosphate extractant. The uranium in the pregnant extractant is then oxidized to the hexavalent state and stripped with a phosphoric acid stripping solution. Hydrolysis of the extractant is decreased by decreasing the proton concentration of the extractant which results from acidic impurities, e.g., sulfuric acid and fluorosilicic acid, originally present in the wet-process phosphoric acid. The proton concentration of the extractant is reduced indirectly by treating the phosphoric acid strip solution (1) with reagents which react with the acidic impurities to form water and an insoluble precipitate which is removed from the stripping solution; (2) with reagents to neutralize the acidic impurities in the stripping solution; or (3) by passing the stripping solution through a suitable ion exchange column.

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Lakeland, FL, United States of America

Alex Magdics