| 摘要 |
<p>1291910 Upgrading the tantalum and niobium contents of tin slags KAWECKI BERYLCO INDUSTRIES Inc 14 Dec 1970 [22 Dec 1969] 59293/70 Heading C1A In the upgrading of the Ta and Nb content of tin slag containing silica, tin slag is first smelted with carbon to form carbides, the slag formed is smelted with iron oxides to convert the tantalum and niobium carbides to their oxides mixed with a product slag and metallic iron, the product slag and iron are removed by leaching with aqueous hydrochloric acid or sulphuric acid to form a residue containing about 30-35% wt. of tantalum and niobium oxides wherein the silica content impairs the filterability of the acid leached mass, the improvement comprising the incorporation of hydrofluoric acid in the leaching liquor in an amount that does not exceed that stoichiometrically equivalent to the silica whereby the hydrofluoric acid selectively attacks the silica and improves the separation of the tantalum and niobium oxides.</p> |
