Process for preparing chromium oxide by recovering chromium-containing electroplating sludge

The invention discloses a process for preparing chromium oxide by recovering chromium-containing electroplating sludge, and belongs to the technical field of chromium-containing electroplating sludge treatment.The process comprises the following steps that sodium carbonate is added into dry sludge, then roasting is conducted, clinker is obtained, deionized water is added into the clinker for water leaching treatment, and leachate is obtained after filtering; sulfuric acid is added into the leachate to adjust the pH value, then sodium metaaluminate is added, and purified liquid is obtained after evaporation and concentration; adding deionized water into the purified liquid, and then crystallizing at room temperature for 6-8 hours to obtain sodium dichromate; the method comprises the following steps: grinding sodium dichromate, adding carbon black into the ground sodium dichromate, heating to 500-550 DEG C, preserving heat for 2.5-3.0 hours, and grinding, washing and filtering a product to obtain chromic oxide.