Method used for extracting iron from red mud by drastic reduction and method used for preparing gel material from secondary tailings

Abstract

The invention discloses a method used for extracting iron from red mud by drastic reduction and a method used for preparing a gel material from secondary tailings, and belongs to the field of comprehensive utilization of resources. The method used for extracting iron from red mud by drastic reduction comprises following steps: Bayer process red mud is dried and crushed; the crushed red mud is mixed uniformly with a reducing agent and an auxiliary agent; the mixture is subjected to drastic reduction in a sealed container in a kiln with oxidizing atmosphere or reducing atmosphere; and the cooled material prepared by reduction reaction is subjected to wet milling and magnetic separation so as to obtain the iron powder of drastic reduction with iron grade of 90% or more, and iron recovery rate of 90% or more. The method used for preparing the gel material from secondary tailings comprises following step: the secondary tailings obtained after magnetic separation is dried, and are mixed uniformly with blast furnace slag, cement clinker, an exciting agent and an early strength agent; and then the secondary tailing gel material is prepared, wherein compressive strength and breaking strength of the secondary tailing gel material both meet the requirements of composite Portland cement 325 standard. According to the methods of the invention, the large amount of residual iron is recycled from the red mud, and the secondary tailings are used for preparation of the gel material, so that waste is transformed into valuables, the recovery of red mud iron resource is realized, and a problem of accumulation of red mud is solved.

Description

technical field [0001] The invention belongs to the field of comprehensive utilization of resources, and in particular relates to a method for preparing cementitious materials by deep reduction of Bayer process red mud to extract iron and secondary tailings. Background technique [0002] Red mud is a red muddy strong alkaline solid waste that remains after the aluminum industry extracts alumina from bauxite. Due to the difference in ore grade, production method and technical level, the red mud output of different manufacturers is also different. Generally speaking, 1.0-2.5 tons of red mud will be produced for every 1 ton of alumina produced. According to incomplete estimates, the current annual discharge of red mud in the world is about 60 million tons, but its utilization rate is only about 15%. So far, no effective way to use red mud in large quantities has been found. Because a large amount of red mud cannot be recycled, most of them are stored in the yard by wet method,...

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Problems solved by technology

In this method, the red mud pellets are directly smelted in a blast furnace, the melting temperature is high, and the energy consumption is large, which is economically unreasonable for low-grade iron-containing red mud. In addition, the amount of reducing agent coke used is 20-30%, and the amount of coke is large. further increased production costs

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