Patent ID: 7718147

Claim:
A process for chemical beneficiation of raw material containing tantalum, niobium, uranium and other elements in mixture, comprising the following steps: (A) the raw material is decomposed by a carbonate-containing solution of ammonium fluoride in a reducing medium at the boiling point of the reaction mixture for no longer than 8 hours wherein said tantalum, niobium and other elements in a mixture of said raw material are converted into complex compounds of ammonium fluoride wherein uranium-6 is reduced to uranium-4 and the combination with uranium-4 found in the raw material is converted to uranium tetrafluoride (UF 4 ) or ammonium uranium fluoride (NH 4 UF 5 ) wherein exhaust gases from said decomposition include ammonia, ammonium fluoride and carbon dioxide, which are recovered by condensation and scrubbing of the exhaust gases; (B) the mixture obtained as a result of the decompositions step according to step A is leached with water, or a solution containing ammonia or a solution containing ammonium fluoride for no longer than 1 hour, without keeping the leaching temperature to remove said ammonium-fluoride complex compounds in said water or solutions, leaving the insoluble compounds of the mixture elements; (C) the mixture obtained in step B is filtered, producing a main filtrate that is an ammonium-fluoride solution containing tantalum and niobium and a sediment of compounds of the mixture elements and said sediment is washed with an ammonium-fluoride solution, water or ammonium solution; (D) the main filtrate of step C is mixed with an ammonium carbonate solution to precipitate tantalum and niobium; and (E) a sediment containing tantalum and niobium precipitated during step D is separated from the carbonate-containing solution of ammonium fluoride carbonate by filtration and then dried and calcinated at a temperature ranging from 400 to 900° C. to obtain the mixture of tantalum and niobium oxides, which are the final product and are suitably further treated by a known process of extraction and separation of tantalum and niobium; a filtrate and a washing/scrubbing solution are combined and recycled as a solution containing ammonium fluoride carbonate for decomposition of the raw material according to step A.