METHOD OF DECOMPOSITION OF WASTES OF REFRACTORY METALS WITH LITHIUM COMPOUND MONOCRYSTALS PRODUCTION Russian patent published in 2004 - IPC

FIELD: chemical industry and hydrometallurgy. SUBSTANCE: the invention presents a method of decomposition of waste products of production of refractory metals with lithium compound monocrystals. The method may be used in reprocessing of waste products of production of refractory metals with alkali metals compound monocrystals, in particular , in production of lithium methatantalate and niobate, with production of high-clean compounds of refractory metals with lithium, fit for repeated monocrystal growing. Waste products of lithium methatantalate or niobate, communited up to particle size of less than 160 microns, are sintered for 1-2 hours with lithium carbonate at its 2-10 % surplus and the temperature of 800-1000 C with production of a cake of the joint of a composition of a refractory metal with lithium in the ortho - form. The produced cake is heated and lixiviated by a mixture of concentrated hydrochloric and hydrofluoric acids taken at ratio of H: L of no more than 0.16 with transformation in a solution, alongside with lithium, and a refractory metal, and hydrofluoric acid is fed in the amount ensuring a molar ratio of the refractory metal and a fluorine equal to 1: 4-7. For the lixiviation they use 35-39 % hydrochloric and 40-47 % hydrofluoric acids. Lixiviation of lithium orthotantalate is conducted at the temperature of 40-70 C, and lithium orthoniabate - at the temperature of 8-50 C. Lithium methatantalate may contain alloying additives of chromium and neodymium, and lithium methaniobate - the additive of magnesium, which in the process of the cake lixiviation are also passing into the solution. Application of the offered method allows within a limited duration of operations of sintering and lixiviations to transform practically all lithium, tantalum or niobium and alloying additives into a solution. At consequent extraction reprocessing of the solution the high-clean compounds of tantalum or niobium are produced, and also lithium chloride, that is easily regenerated into lithium carbonate. All produced products may be reutilized for preparation of a charge in production of monocrystals of methatantalate or lithium niobate. At realization of a method the standard equipment is used. EFFECT: the method allows to transform practically all lithium, tantalum or niobium and alloying additives into a solution with possibility of their following regeneration for usage in monocrystals production. 7 cl, 11 ex