GB476558A - A process of treating materials containing tantalum and/or niobium - Google Patents

Abstract

Materials containing tantalum and/or niobium, for example, ores or metallurgical bye-products, are subjected to a reducing operation at a sufficiently high temperature to melt the mass, and to reduce the reducible oxides of the metals present, including those of the tantalum and/or niobium, with formation of a slag containing the major part of the silica and lime present in the raw material and of an alloy of tantalum and/or niobium with another metal or metals present in the raw material, the slag being then separated from the alloy which is subjected to a chemical treatment to recover the tantalum and/or niobium, preferably in oxide form. Metals forming alloys with the tantalum and/or niobium are iron, tin, copper, titanium. In an example, coke and charcoal in excess are added to a slag containing tantalum, niobium, iron, silica, alumina, calcium, magnesium, titanium, manganese and tin and the charge heated for 17 hours in an electric arc furnace at 1400 DEG C. After separation of the slag, the metallic mass is treated with 10--20 DEG B<\>ae. sulphuric acid at 90--95 DEG C. to eliminate the iron, manganese and tin, and then with a mixture of 50--60 DEG B<\>ae. sulphuric acid and 60--80 per cent hydrofluoric acid to eliminate the silicon; this latter treatment may be replaced by an attack with 10--20 per cent caustic alkali at 60--100 DEG C. The residue is roasted at 800--1000 DEG C. to obtain tantalum and niobium oxides, which may be reduced, for example, with aluminium, calcium, magnesium or silicon to obtain the metals, or alloys thereof, e.g. ferro-alloys. Lime and/or silica is generally added to the furnace charge for obtaining a fluid slag. Bauxite and/or fluorspar are sometimes added as fluxes. The furnace temperature may be as low as 1100 DEG C.ALSO:Materials containing tantalum and/or niobium, for example, ores or metallurgical bye-products, are subjected to a reducing operation at a sufficiently high temperature to melt the mass and to reduce the reducible oxides of the metals present, including those of the tantalum and/or niobium, with formation of a slag containing the major part of the silica and lime present in the raw material and of an alloy of tantalum and/or niobium with another metal or metals present in the raw material, the slag being then separated from the alloy which is subjected to a chemical treatment to recover the tantalum and/or niobium, preferably in oxide form. Metals forming alloys with the tantalum and/or niobium are iron, tin, copper, titanium. In an example, coke and charcoal are added in excess to a slag containing tantalum, niobium, iron, silica, alumina, calcium, magnesium, titanium, manganese, and tin, and the charge heated for 17 hours in an electric arc furnace at 1400 DEG C. After separation of the slag, the metallic mass is treated with 10-20 DEG B<\>ae., sulphuric acid to eliminate the iron, manganese and tin, and then with a mixture of 50-60 DEG B<\>ae. sulphuric acid and 60-80 per cent hydrofluoric acid to eliminate the silicon; this latter treatment may be replaced by an attack with 10-20 per cent caustic alkali at 60-100 DEG C. The residue is roasted at 800-1000 DEG C. to obtain tantalum and niobium oxides, which may be reduced, for example, with aluminium, calcium, magnesium, or silicon to obtain the metals, or alloys thereof, e.g. ferro-alloys. Lime and/or silica is generally added to the furnace charge for obtaining a fluid slag. Bauxite and/or fluorspar are sometimes added as fluxes. The furnace temperature may be as low as 1100 DEG C.