Method for preparing 4A zeolite from gangue serving as raw material through two-step hydrothermal synthesis

Abstract

The invention discloses a method for preparing 4A zeolite from gangue serving as a raw material through two-step hydrothermal synthesis. The method comprises the following steps: firstly, crushing andgrinding gangue, performing thermal activation pretreatment, mixing the gangue subjected to thermal activation and sodium carbonate uniformly, and melting at high temperature to obtain a molten mixture; secondly, mixing the molten mixture and water under the water solution condition to dissolve out sodium silicate, filtering to obtain filter residues and drying the filter residues; thirdly, completely stirring the dried filter residues and a sodium hydroxide solution under the alkali dissolution condition, filtering to obtain a silicon aluminum solution, and ageing the silicon aluminum solution to obtain a precursor; finally, performing hydrothermal crystallization treatment on the precursor, and filtering, water-washing and drying to obtain the 4A zeolite. According to the synthesis method, the gangue serves as the raw material, the gangue is subjected to high-end resource-based development and utilization, and the gangue does not need to be subjected to acid leaching pretreatment, so that secondary pollution on the environment is reduced; and an aluminum source does not need to be added in the synthesis process, so the method is simple, high in operability and low in cost.

Description

technical field [0001] The invention relates to a method for preparing 4A zeolite, in particular to a method for hydrothermally synthesizing 4A zeolite in two steps using coal gangue as a raw material. Background technique [0002] 4A zeolite is a kind of artificial zeolite synthesized by humans. It does not pollute the environment, has strong ion exchange capacity and adsorption performance, and has great application potential in general daily use, petrochemical, smelting and other industries and high-tech fields. [0003] At present, there are three main raw materials for synthesizing 4A zeolite: chemical raw materials, natural minerals and industrial waste. Chemical raw materials are raw materials for total chemical synthesis and auxiliary raw materials for semi-synthetic methods. They mainly include sodium hydroxide, water glass, sulfuric acid, alumina, etc., and their cost is high and their operation is complicated. Natural minerals are based on SiO 2 and Al 2 o 3 M...

AI Technical Summary

Problems solved by technology

[0004] At present, the main method of using coal gangue as raw material to synthesize 4A zeolite is the alkali fusion hydrothermal synthesis method, such as the Chinese patent with the publication number CN1346794A "Method for preparing A-type zeolite by high-temperature alkali fusion-hydrothermal crystallization using coal gangue as raw material" , the coal gangue is alkali-fused at high temperature in an alkali flux, and then water is added to the alkali-fused gangue to crystallize and synthesize zeolite, wherein an aluminum source needs to be supplemented to adjust the silicon-aluminum ratio; for example, the Chinese patent "a kind of coal The method for preparing A-type zeolite from gangue "reacts calcined coal gangue and alkali flux at high temperature, and the alkali melt is dissolved in water to remove iron and then added aluminum salt to crystallize to synthesize zeolite. Although this method is simple and easy, silicon Aluminum source, but still need to supplement aluminum salt, the ratio is difficult to control, and the operability is weak; such as the Chinese patent "a method for preparing high whiteness A-type zeolite from coal gangue" with the publication number CN101214973A, after the coal gangue is alkali-fused Water-soluble, add aluminum salt aging hydrothermal crystallization to synthesize zeolite, add complexing agent to whiten during the crystallization process, although this method synthesizes high-purity and high-whiteness A-type zeolite, but adding aluminum salt and complexing agent causes High cost and weak operability

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