China Nonferrous Metallurgy

Guangxi is the main production base of alumina, with an annual output of about 15 million tons of red mud. The red mud contains high iron, and is rich in rare, dispersed, and rare earth metal elements, which has great resource recovery value. The four goals for achieving high value comprehensive utilization of red mud are harmless treatment of alkali, thorough separation of iron and aluminum, enrichment of “three rare” elements, and low-cost treatment.This paper comprehensively analyzes the current status of comprehensive utilization technology of red mud, and considering the rich agricultural and forestry resources in Guangxi, proposes a process route of using biomass gas reduction roasting high iron red mud-leaching-magnetic separation. Pyrolysis gas carbon cogeneration technology can convert Guangxi’s rich agricultural and forestry wastes into high-quality combustible gas. The by-product of gasification is biomass charcoal, which can be used as a reducing agent in the alkali reduction roasting process, significantly reducing the cost of auxiliary materials.The red mud mixed with sodium carbonate is subjected to reduction roasting and then wet grinding for dissolution. The main component of the dissolution liquid is sodium aluminate, and aluminum hydroxide and sodium carbonate are recovered. After magnetic separation of iron ore, the remaining part is the “three rare” enriched slag, which can recover titanium, scandium, rare earth, etc.The proposed process route achieves complete separation of iron and aluminum and enrichment of “three rare” elements, and can be processed at a low cost. The added alkali can be recycled, providing a new path for low-cost and efficient utilization of Guangxi red mud and recovery of “three rare” metals.