Preparation method of ammonium persulfate crystal

Abstract

The invention discloses a preparation method of an ammonium persulfate crystal, and the method comprises the following steps of: using an ammonium persulfate-ammonium sulfate mixed solution as a mother solution, adding a seed crystal and carrying out staged cooling and crystal growing treatment to obtain an ammonium persulfate crystal with uniform particle size distribution, wherein the staged cooling and crystal growing treatment refers to staged cooling, heat preservation and crystal growing of the mother solution, and the staged cooling, heat preservation and crystal growing are carried outin five stages, and the five stages include: first time of cooling and crystal growing, second time of cooling and crystal growing, third time of cooling and crystal growing, fourth time of cooling and crystal growing, and fifth time of cooling and crystal growing; the step of adding the seed crystal is carried out after the first time of cooling, and the first crystal growing treatment is carried out after the seed crystal is added. Through staged cooling and crystal growing treatment, the crystal growing time is prolonged; the seed crystal is added in the crystallization process, and the stirring size is increased by using a stirring paddle with a large diameter, so that the prepared ammonium persulfate finished product is uniform in particle size distribution and relatively large in crystalline particles, and is not easy to cake.

Description

technical field [0001] The invention relates to the technical field of inorganic salt crystallization, in particular to a preparation method of ammonium persulfate crystallization. Background technique [0002] Ammonium persulfate is colorless monoclinic crystal or white powder crystal, easily soluble in water, and its solubility increases in warm water. Dry ammonium persulfate has good stability, and ammonium persulfate is prone to moisture and caking in humid air. After moisture absorption and deliquescence, there is a relatively obvious van der Waals force between the crystals, and finally crystal bridges are formed, resulting in a large amount of agglomeration of the product. This is why the ammonium persulfate clumped. [0003] At present, the domestic traditional ammonium persulfate production crystallization process basically uses direct rapid cooling to obtain crystallized products. The main problems of this process are: [0004] 1) The fast cooling rate makes the...

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Problems solved by technology

[0004] 1) The fast cooling rate makes the supersaturation of the system too high, beyond the metastable zone, and the secondary nucleation phenomenon is serious, resulting in a large number of small crystals;

[0005] 2) Although the use of a small stirring paddle can stir the crystals (no crystals sink to the bottom of the crystallizer), the mixing degree of the solution in the upper part of the crystallizer is poor, which will easily cause the supersaturation of the upper solution to accumulate excessively, resulting in secondary formation Nuclei, producing a large number of small crystals;

[0006] 3) Direct cooling, crystallization is not easy to nucleate, and the nucleation particle size is uneven, resulting in a large number of small crystals

[0007] A large number of small crystals formed in the crystallization process of ammonium persulfate production can easily cause moisture absorption and agglomeration of ammonium persulfate

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