Chromium salt is the "MSG" in the industrial field and has an irreplaceable status. The main products include sodium chromate, sodium dichromate, chromic anhydride, chromium trioxide and basic chromium sulfate. China is the world's largest producer and consumer of chromium salts, with output accounting for about 40% of the world. Every ton of sodium chromate produced by the existing process discharges 1.0 to 1.5 tons of hazardous waste containing chromium. These wastes can easily enter the surrounding soil, groundwater and air, destroy the organisms, and cause serious environmental pollution. Ranked first in the heavily polluting industry.
The research on the preparation of chromium salt products by electrochemical method started in the 1960s, and sodium dichromate or chromic anhydride was synthesized from sodium chromate by means of ion-exchange membrane electrolysis. With the breakthrough of ion-exchange membrane chlor-alkali technology in the 1980s, the research and development progress of this technology was significantly accelerated. In 1996, the US ELEMENTIS company built the first device for the production of sodium dichromate from ion membrane electrolysis, with an annual production capacity of 55,000 tons. In 2009, LANXESS company built a 20,000 tons scale ion membrane electrolysis chromic anhydride production line in Newcastle, South Africa. The technology of electrochemical preparation of chromium salts is strictly controlled by the production enterprises, and a strict technical blockade is imposed on China.
Recently, the team of Professor Feng Haitao of ISL summarized the chromium salt clean production process based on the electrochemical method of the Salt Lake Institute and its team. In 1999, the team of Zheng Zhulin from ISL successfully realized the preparation of sodium dichromate from industrial sodium chromate by ion membrane electrolysis, which opened a prelude for Chinese scholars to study the preparation of chromium salt products by electrochemical method. Since 2007, ISL has continuously deepened the research and development of chromium salt products prepared by electrochemical methods, and established a long-term, stable, and effective cooperative relationship with chromium salt enterprises, and gradually promoted the application of the development and research of new technologies in the ion membrane electrolysis method. Based on the preparation of sodium dichromate technology, the team of Professor Feng Haitao have developed a set of electrochemically based chromium salt clean production process, covering three major processes and four parent chromium salt products.
