Vanadium sludge from alumina ore processing liquor - impurities reduced by preliminary crystallisation step at intermediate temperature

摘要

The liquor resulting from treatment of alumina ores with caustic alkali solution is cooled to 40-65 degrees C and held until a precipitate is formed; the latter is separated and the liquor further cooled to 20-30 degrees C to precipitate vanadium sludge. PRef. the liquor is diluted after separation of the first precipitate. The initial precipitation partially removes impurities, partic. Na2SO4, K2SO4, Na2CO3 and NaF thereby increasing the concentration of vanadium in the final sludge and facilitating its recovery. Furthermore the presence of sparingly soluble vanadium salts in the sludge is minimised.