METHOD OF PREPARING REFRACTORY METALS FROM LOPARITE CONCENTRATE Russian patent published in 2000 - IPC

FIELD: hydrometallurgy. SUBSTANCE: process includes grinding of concentrate to particle size at least 0.075 mm, size separation, stripping of loparite concentrate with concentrated nitric acid at atmosphere pressure and temperature above 100 C, hydrofluoric acid-assisted formation of tantalum and niobium fluoride compounds from concentrate stripping products, and extraction of these compounds by tributyl phosphate. Formation of mentioned fluoride compounds is assured by dissolution of hydrate cake of refractory metal oxides in at least 40% hydrofluoric acid, said cake being formed after stripping of loparite concentrate with simultaneous formation of fluorotitanic acid. Once tantalum and niobium extracted, concentration of raffinate solution is 1.5-2.0-fold decreased by evaporation at 105-108 C and hydrofluoric acid is distilled off for recycle in presence of concentrated sulfuric acid. Distillation residue is treated to crystallize titanyl sulfate monohydrate from which final product in the form of titanium dioxide is obtained, whereas mother solution containing concentrated sulfuric acid is reused to recover hydrofluoric acid from evaporated raffinate solution. EFFECT: simplified technology and increased economical efficiency. 2 cl, 2 tbl