A method of red mud acid treatment for alkali removal

Abstract

The invention discloses a method for acid treatment and alkaline removal of red mud. The method comprises the following steps: 1) adding red mud and calcium chloride into hydrochloric acid and leaching, thereby acquiring a leachate and a leaching residue; 2) adding a mixture of sodium carbonate, activated carbon and resin into the leachate acquired in the step 1), and then separating solid from liquid, thereby acquiring a filtrate containing sodium chloride; 3) concentrating the filtrate containing sodium chloride acquired in the step 2), and then adopting a bipolar membrane for electrodialysis, thereby acquiring sodium hydroxide and hydrochloric acid, wherein the acquired hydrochloric acid is returned to the step 1) and is used as a leaching agent, and the sodium hydroxide is returned toa Bayer process and is used as a raw material of bauxite. The method has a simple process and is low in cost; sodium in the red mud is recycled; the leaching residue is deeply subjected to alkaline removal and can be directly used as a raw material of building materials; and meanwhile, the hydrochloric acid is recycled and reused as the leaching agent of the red mud; the whole process realizes zero release and recycling utilization of resources; a new way suitable for industrialization is opened for the comprehensive utilization of the red mud.

Description

technical field [0001] The invention belongs to the technical field of comprehensive utilization of solid waste, and in particular relates to a method for removing alkali by acid treatment of red mud. Background technique [0002] Red mud is a strong alkaline solid waste discharged during the production of alumina. It is called red mud because of its high iron oxide content and red color. In the Bayer process, 1 to 1.5 tons of red mud is discharged for every 1 ton of alumina produced. For sintering and combined processes, 1.5 to 2.5 tons of red mud are discharged for every 1 ton of alumina produced. As of 2015, the global stockpile of red mud has exceeded 3.5 billion tons and is increasing at a rate of 120 million tons per year. At present, my country's annual red mud discharge reaches 60 million tons, and the total red mud stockpile exceeds 600 million tons. [0003] Red mud has strong alkalinity and high salt content. Its ecological disposal and resource utilization hav...

AI Technical Summary

Problems solved by technology

Although experts at home and abroad have done a lot of research work on red mud, the biggest problem is that there is no low-cost application

Traditional acid leaching uses sulfuric acid, hydrochloric acid or nitric acid as the leaching agent, and is carried out under pressure to leach the silicon in the red mud in the form of silica gel, which makes it difficult to filter the red mud acid leaching residue and realize industrialization. Production

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