A process for preparing 4a molecular sieve by using imported trihydrate bauxite

Abstract

The invention provides a process for preparing a 4A molecular sieve by use of imported trihydrate bauxite. The process specifically comprises the following steps: preparing alkali liquid with Na2O concentration of 2.5-3mol / L for a dissolving reaction; based on the Na2O concentration of the alkali liquid, adding bauxite for a dissolving reaction according to the causticity ratio of 1.2-1.8 of the slurry after dissolution, and controlling the reaction temperature at 90-100 DEG C to obtain dissolved slurry; adding a flocculating agent into the dissolved slurry according to the concentration of 50-200ppm, and performing settling separation to obtain supernate and red mud; filtering to obtain a sodium aluminate solution; and preparing a 4A molecular sieve by use of the obtained sodium aluminate solution. The process provided by the invention guarantees the dissolution rate of aluminum oxide in the bauxite and effectively utilizes the silicon dioxide (beneficial to 4A zeolite production) in the bauxite so that the utilization rate of bauxite is greatly improved.

Description

technical field [0001] The invention relates to the field of aluminosilicate compounds, in particular to a process for preparing 4A molecular sieves by using imported trihydrate bauxite. Background technique [0002] At present, the hydrothermal synthesis method commonly used in industry to produce 4A zeolite molecular sieves mostly uses imported bauxite, and the sodium aluminate solution produced by dissolution with liquid alkali under certain conditions is used as the aluminum source, and then passed through the process with sodium silicate under certain conditions. Slurry, aging, crystallization and other steps to obtain 4A zeolite products. Imported gibbsite-type bauxite is easier to dissolve under alkaline conditions. The dissolution rate of alumina in high-grade bauxite is relatively high. For example, in the method disclosed in "Optimization of Dissolution Process Conditions for Production of Aluminum Oxide Using Foreign Bauxite" published in the tenth issue of the m...

AI Technical Summary

Problems solved by technology

The dissolution rate of alumina in high-grade bauxite is relatively high. For example, in the method disclosed in "Optimization of Dissolution Process Conditions for Production of Aluminum Oxide Using Foreign Bauxite" published in the tenth issue of the magazine "Light Metals" in 2001, The alumina content of the ore is 49~55%, the A / S is between 8-10.5, and the actual dissolution rate of alumina can reach nearly 90%, but now high-grade bauxite is very rare, and the commonly used imported Sanshui In bauxite-type bauxite, the content of alumina is usually 45%-50%, and the A / S is between 2-3. Using such bauxite, the actual dissolution rate of alumina is only about 75%, which contains A large amount of silica enters the waste residue and cannot be effectively utilized, resulting in a low overall utilization rate of bauxite

[0003] Since most 4A zeolite manufacturers continue to use the original bauxite dissolution control conditions, the dissolution of alumina in bauxite is not complete, resulting in the loss of alumina in bauxite, and people are pursuing the dissolution rate of alumina. Ignore the silica that is useful for 4A zeolite production in bauxite, so that silica becomes sodium silicate slag and enters the red mud dissolved in bauxite, resulting in waste

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