Alkali metal catalyst recovery system

A process for the recovery of alkali metal compounds from a mixture of solids including char particles, ash containing iron, aluminum and silicon compounds, and alkali metal catalyst residues, said mixture being produced by the high temperature gasification of coal in the presence of an alkali metal-containing catalyst, which comprises magnetically separating magnetic iron constituents from said mixture of solids and recovering solids of reduced iron content;

• separating said solids of reduced iron content into a first fraction of relatively high carbon content and relatively low ash content and a second fraction of relatively low carbon content and relatively high ash content;
• extracting alkali metal compounds, aluminum compounds, and silicon compounds from said second fraction with a solution of an acid which reacts with alkali metal compounds present in said fraction to form soluble salts and recovering a spent acid solution enriched in alkali metal compounds;
• raising the pH of said spent acid solution to a level above about 7.0 and removing precipitated aluminum hydroxide from said spent solution;
• heating said spent solution sufficiently to drive off water and precipitate silicon solution sufficiently to drive off water and precipitate silicon compounds;
• and recovering an alkali metal compound solution.