METHOD OF PROCESSING OF LAPARITE CONCENTRATE Russian patent published in 2001 - IPC

FIELD: metallurgy. SUBSTANCE: method consists in grinding of laparite concentrate to particles sizing, at least, 0.075 mm with classification; breaking down of laparite concentrate with weak 47-55% nitric acid at temperature of 115-118 C and continuous moving of pulp through row of successively joined reactor vessels. Hydrate cake of refractory metal oxides obtained by breaking down of laparite concentrate is washed off with water to produce pure hydrate cake and active combined nitrate solution of rare- earth elements with impurities. Said solution is neutralized and deactivated with precipitation of all impurities including thorium and mesothorium. Pure nitrate solution of rare-earth elements is treated with sodium carbonate and sum of carbonates of rare-earth elements is precipitated. Filtrate is concentrated by evaporation to concentration of 500-600 g/l and subjected to hydrolysis at temperature of 600-800 C to produce elementary nitrogen, oxygen, carbon dioxide in exit gases and also sodium carbonate. The latter is directed for neutralization of nitrate solution and precipitation of carbonates of rare-earth elements. Exit gases are subjected to scrubbing with water and discharged to atmosphere. EFFECT: reduced expenditures and cost of product. 1 ex