METHOD OF CLEANING OF LITHIUM-7 HYDROXIDE Russian patent published in 2005 - IPC

FIELD: methods of cleaning of lithium hydroxide.

SUBSTANCE: the invention is methods of cleaning of lithium hydroxide. A solution of lithium-7 hydroxide is exposed to subevaporation till its haziness and falling out in a crystal of 0.7-1.0 % of lithium-1 hydroxide. Then the solution is filtrated and evaporated till production of a pulp. The filtration of the solution after subevaporation is carried out in succession in the tight filters with a fabric and metal-ceramic filtering layer with an average size of pores of 0.15 microns at vacuumization of the feeding pipeline. Production operations of crystals separation from a mother solution and their drying are carried out in one apparatus - a centrifugal machine till obtaining crystals of lithium - 7 hydroxide with the contents of the base substance of 55-56 %. The whole process of cleaning is carried out in the tight equipment in a noble gas medium. The method ensures cleaning of lithium - 7 hydroxide from a carbonate-ion up to the contents of ≤ 0.5 % and from the insoluble impurities, and also allows to obtain a product with the share of the base substance of 55-56 %. The product may be used in the capacity of the passivating additive in the contours of the heavy-water nuclear reactors.

EFFECT: the invention ensures production of crystals of lithium - 7 hydroxide with 55-56 % of the base substance, cleaned from a carbonate-ion up to ≤ 0.5 % and from the insoluble impurities, and may be used as passivating additive in the contours of the heavy-water nuclear reactors.

3 cl, 1 tbl