Patent ID: 6068677
Filing Date: 2000-05-30
Classification: C22B,Y02P,Y10S

Abstract:
A method for processing waste or waste fractions comprising:pyrolyzing, gasifying, and/or combusting charging material obtained from waste or waste fractions to produce residues, the charging material containing, as metallic components, at least chrome, iron, and other constituents for forming chrome-iron spinel;prior to any oxidation of the residues, heating the residues under reducing conditions to reduce the metallic components and form a metal bath and thereafter subjecting the reduced metallic components to stepwise oxidation, the stepwise oxidation including an oxidation stage in which sufficient amounts of oxygen are present to ensure quantitative reaction of the reduced metallic components to form a chrome-iron spinel;drawing off the chrome-iron spinel form a surface of the metal bath and reducing the chrome-iron spinel with carbon to ferrochromium-carbon alloy; andafter said drawing off of the chrome-iron spinel, applying lime or limestone onto the surface of the metal bath and raising the oxidation potential to form calcium ferrite slag.