Abstract: This invention provides a novel method for separating alkaline salts from industrial byproduct mixtures of solid containing a source of the alkaline salt and a free carbonaceous material. In one embodiment, the industrial byproduct may be a mixture of solid materials that comprises: sodium carbonate, hydrate phases of sodium carbonates, free carbon particulates, water and minor amounts of insoluble materials as impurities. An external source of heat is initially applied to the byproduct mixture to raise the temperature of the free carbon particulates to the ignition point at which time a source of oxygen, introduced into the byproduct mixture, reacts with the heated carbon particulates and combine exothermally to form carbon dioxide gas and autogenously release thermal energy.