A PROCESS FOR THE MANUFACTURE OF SODIUM DICHROMATE FROM CHROMITE ORE OR CHROMIUM CONTAINING SLAG

摘要

A process for the manufacture of sodium dichromate from chromite ore or chromium containing slag which comprises preparing a blend of (1) chromite ore or chromium containing slag (ii) sodium sulphate and (iii) limestone in proportions of utmost 1 : 1 : 0.8 parts by weight dry roasting the blend at temperature around 1000degrees C in a current of air followed by subjecting the roasted material to a step of leaching in water, separating the liquid and solid portions the solid portion containing unconverted ore, which is reused in the process, the liquid portion containing sodium chromate being then reacted with sulphuric acid thereby to produce sodium dichromate as product and sodium sulphate as by product, the product and by-product being separately recovered in a known manner.