PROCESS FOR RECOVERING RARE METALS FROM THE COMBUSTION RESIDUE OF COAL BY DIGESTION

摘要

ABSTRACTThe invention relates to a method for recovering raremetals from the combustion residues of various coals, in parti-cular brown coals. The recovery is performed by digestion, moreparticularly by aqueous and/or dilute alkaline and/or dilute acidicdigestion, where two or three of these steps can be combined inany desired order or they may be carried out separately. Duringdigestion the concentration of the solution is monitored and thesubsequent digestion steps are terminated at a desired concentra-tion. The solid and liquid phase are then separated and the raremetals are isolated from the liquid phase while the solid phase,optionally after neutralization and/or washing can be utilizedfor example as a source of energy.