PRODUCTION PROCESS OF CHROMIUM OXIDE FROM MAGNESIA-CHROME WASTED FIREPROOF MATERIALS

摘要

PURPOSE: A chromium oxide powder using magnesia-chrome wasted fireproof materials is produced wherein a hexavalent chromium generated in disposal is stably treated so that high value added chemicals are produced. CONSTITUTION: A production step is as follows: (1) a first step wherein the wasted fireproof materials are crushed below 140 mesh, reacted with a sulfuric acid, filtered and the residuals are separated; (2) a second wherein the separated residuals are reacted with an alkali under oxygen or air condition at 500-800°C; (3) a third wherein a reactant fused in alkali is dissolved in a water to extract the hexavalent chromium component; (4) a fourth wherein the extracted Na2CrO4 is converted to a H2Cr2O7 by a sulfuric acid and the converted H2Cr2O7 is reacted with a sulfuric acid and a reducing agent to reduce the hexavalent chromium; and (5) a fifth wherein the reduced Cr2(SO4)3 is treated in a neutral condition and then a chromium oxide powder is produced through filtering, drying and treating with heat.