New technology for comprehensive utilization of aluminum-chromium residue from chromium salts production
(1. School of Metallurgical Science and Engineering, Central South University, Changsha 410083, China;2. Gansu Jinshi Chemical Engineering Corporation, Ltd., Zhangye 734000, China)
Abstract: Colloidal aluminum-chromium residue(ACR) was mass-produced in chromate production process, and the large energy consumption and high recovery cost existed in traditional methods of utilizing such ACR. To overcome those problems, a new comprehensive method was proposed to deal with the ACR, and was proven valid in industry. In the new process, the chromate was separated firstly from the colloidal ACR by ripening and washing with additives, by which more than 95% hexavalent chromium was recovered. The chromium-free aluminum residue(CFAR), after properly dispersed, was digested at 120−130 ℃ and more than 90% alumina can be recovered. And then the pregnant aluminate solution obtained from digestion was seeded to precipitate aluminum hydroxide. This new method can successfully recover both alumina and sodium chromate, and thus realize the comprehensive utilization of ACR from chromate industry.
Key words: utilization; aluminum-chromate residue(ACR); aluminum hydroxide; sodium chromate hydrate