Uranium control in phosphogypsum. [In wet-process phosphoric acid production]
In wet-process phosphoric acid plants, both previous and recent test results show that uranium dissolution from phosphate rock is significantly higher when the rock is acidulated under oxidizing conditions than under reducing conditions. Excess sulfate and excess fluoride further enhance the distribution of uranium to the cake. Apparently the U(IV) present in the crystal lattice of the apatite plus that formed by reduction of U(IV) by FE(II) during acidulation is trapped or carried into the crystal lattice of the calcium sulfate crystals as they form and grow. The amount of uranium that distributes to hemihydrate filter cake is up to seven times higher than the amount that distributes to the dihydrate cake. About 60% of the uranium in hemihydrate cakes can be readily leached after hydration of the cake, but the residual uranium (20 to 30%) is very difficult to remove economically. Much additional research is needed to develop methods for minimizing uranium losses to calcium filter cakes.
- Research Organization:
- Oak Ridge National Lab., TN (USA)
- DOE Contract Number:
- W-7405-ENG-26
- OSTI ID:
- 5914355
- Report Number(s):
- CONF-801161-2; ON: DE82004096
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS
ACTINIDES
ALKALINE EARTH METAL COMPOUNDS
APATITES
CALCIUM COMPOUNDS
CALCIUM SULFATES
DISSOLUTION
ELEMENTS
FLUORIDES
FLUORINE COMPOUNDS
GYPSUM
HALIDES
HALOGEN COMPOUNDS
HYDROGEN COMPOUNDS
INORGANIC ACIDS
METALS
MINERALS
ORE PROCESSING
OXYGEN COMPOUNDS
PHOSPHATE ROCKS
PHOSPHORIC ACID
PROCESSING
PRODUCTION
REMOVAL
ROCKS
SEDIMENTARY ROCKS
SULFATES
SULFUR COMPOUNDS
URANIUM