PROCESS FOR PREPARING SODIUM BICHROMATE SOLUTION Russian patent published in 1994 - IPC

FIELD: inorganic chemistry. SUBSTANCE: sodium bichromate solution is prepared by oxidizing roasting of chromium ore in alkaline medium. The resulting roasted product is leached with water or aqueous chromate solution, insoluble reagents is filtered off. The filtrate is evaporated, the resulting concentrate is acidified with carbon dioxide in vacuum and cooled to give sodium bicarbonate as dihydrate which is recovered. The treatment of the resulting sodium bichromate solution is carried out by cooling it to temperature -25 C for 60 min. The end product solution contains 56.2 % by weight of Na₂Cr₂O₇·2H₂O. EFFECT: increased stability.