GB470540A - Improvements in or relating to the extraction of heavy metals from phosphatic ores, slags, and like materials containing them - Google Patents

Abstract

In the extraction of heavy metals such as vanadium, uranium, tungsten, molybdenum, tin, chromium, titanium, tantalum, and niobium from phosphatic ores, slags, or like materials containing them, the initial material is roasted or smelted under strongly oxidizing conditions in the presence of fluorides and of alkaline-earth metal oxides, so that in the subsequent leaching step for extracting the soluble heavy metal compounds phosphoric acid remains in the residue in the form of a double salt with fluorine and the alkaline-earth metal oxide. In one example, a pig iron slag containing phosphates and vanadates is subjected to chlorination roasting at 800 DEG C. in admixture with sodium chloride and with addition of fluorspar and lime. On leaching with sodium carbonate solution substantially all the phosphoric acid remains in the residue. In a second example, a uranium ore containing phosphate is roasted at 850 DEG C. with the addition of lime and fluorspar, and leached with sodium carbonate solution, the phosphate content of the liquor being very small. Strongly oxidizing conditions during roasting are obtained either by employing a large excess of air or by adding oxidizing agents such as alkali metal nitrates or chlorates.