Concentration and Extraction of Thorium

The principal steps in producing refined thorium compounds from thorium-bearing ores are concentration of thorium minerals, extraction of thorium from concentrates, purification or refining of thorium, and conversion to metal or the thorium compound finally wanted. This section describes the concentration of monazite, the principal source of thorium in the past the extraction of thorium from monazite and the recovery of thorium from leach liquors by solvent extraction. Purification of thorium is described in Sec. 9 and conversion in Sec. 10. 

Monazite is usually a minor constituent of deposits of other minerals, all of which must be separated and processed for a profitable venture. As an example, the mineral constituents of beach sands in Travancore, India, which are dredged for their zirconium, titanium, thorium, and rare-earth content, are as follows  

Althou the principal constituents of monazite are rare earth and thorium phosphates, its composition varies widely within a given deposit and from place to place. Table 6.16 gives the composition of monazite concentrates from different locations. 

Monazite is chemically very inert. Two general methods that are used for opening up monazite and making its constituents sufficiently reactive to permit extraction and separation of thorium, uranium, and rare earths are 

Reaction with hot, concentrated caustic soda solution 

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