Method for producing sodium aluminate by treating Bayer-process red mud through andradite one-step alkali thermal method

Abstract

The invention relates to a method for producing sodium aluminate by treating Bayer-process red mud through an andradite one-step alkali thermal method. The method comprises the following steps: S1: mixing the red mud, sodium ferrite or calcium ferrite, active lime and a circulating mother solution to prepare raw material ore pulp; S2: carrying out alkali thermal dissolution reaction on the raw material ore pulp; after reacting, obtaining dissolved-out ore pulp; S3: diluting the dissolved-out ore pulp to obtain a diluting solution; carrying out liquid-solid separation on the diluting solution to obtain dissolved-out dreg and a dissolved-out solution; S4: after evaporating the dissolved-out solution, adding a crystal seed, crystallizing and carrying out solid-liquid separation to obtain a sodium aluminate solid and a high-molecular-ratio sodium aluminate solution; S5: blending the high-molecular-ratio sodium aluminate solution to prepare the circulating mother solution used in step S1. According to the method provided by the invention, aluminum oxide and sodium oxide in the red mud are recycled so that the alkali content in the dissolved-out dreg is reduced to be 0.5 percent or below and the red mud can be used as raw materials including cement, concrete, an iron-melting adhesive and the like; the method provided by the invention can be used for consuming a lot of the red mud so that the recycling of the red mud is realized and the green utilization effect of resources is realized.

Description

technical field [0001] The invention belongs to the technical field of sodium aluminate production, and in particular relates to a method for producing sodium aluminate by treating Bayer process red mud with one-step alkali-thermal treatment of andandroid. Background technique [0002] Red mud is the waste residue produced during the production of alumina. It is red because it contains a large amount of iron oxide, so it is called red mud. The output of red mud varies with ore grade, production method and technical level. Every time 1 ton of alumina is produced in my country, 1.0 to 1.7 tons of red mud will be produced. At present, the cumulative accumulation of red mud exceeds 300 million tons. A large amount of red mud cannot be effectively used and can only be stacked in a large area, which not only takes up a lot of land, but also causes serious pollution to the environment due to the high alkalinity of the red mud. As of 2016, the cumulative stockpiles reached more th...

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Problems solved by technology

However, the above-mentioned dealkalization methods all have problems in varying degrees. The effect of the lime dealkalization method under normal pressure is unsatisfactory and the cost is high under high pressure; Alkali is ineffective; chloride ions in magnesium chloride and ammonium chloride dealkalization will corrode equipment and is not conducive to the subsequent application of red mud; CO 2 Suspension dealkalization, in which CO 2 Only for Na in red mud 2 O·Al 2 o 3 、Na 2 SiO 3 and Na 2 CO 3 works, but for Na 2 O·Al 2 o 3 1.7SiO2 2 ·nH 2 O does not work, and most of the sodium in red mud is in the form of Na 2 O·Al 2 o 3 1.7SiO2 2 ·nH 2 The form of O exists, so the removal efficiency of this method is not high; in the lime-sulfuric acid combined dealkalization method, the acid method and the alkali method coexist, and it is easy to waste raw materials.

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