Patent ID: 8603428

Claim:
A method for producing calcium carbonate and vanadium comprising the steps of; a) extracting alkaline industrial waste and by-products using as a first extraction solvent an aqueous solution of a salt formed from a weak acid and a weak base, whereby a first residue is allowed to settle and a calcium-rich first filtrate is formed, b) filtering, whereby the first filtrate is separated from the first residue, c) carbonation of the calcium-rich first filtrate using a carbonation gas, whereby calcium carbonate precipitates and a second filtrate is formed, d) filtering, whereby the calcium carbonate is separated from the second filtrate, e) dissolving the first residue using a second extraction solvent, whereby a vanadium-lean second residue is allowed to settle and a vanadium-rich third filtrate is formed, and f) filtering, whereby the second residue is separated from the third filtrate.