A kind of method prolonging the shelf-life of thiourea dioxide product

Abstract

The invention specifically relates to a method for prolonging the shelf life of thiourea dioxide products. The technical plan is: under the conditions of 0~30°C and 300~600r / min rotating speed, add crystal seeds to the saturated aqueous solution of thiourea dioxide, grow the crystals, and obtain a suspended crystal slurry; then add and dissolve the suspended crystal slurry Analyzing agent, elution crystallization, filtration and drying to obtain thiourea dioxide crystals, the crystal product meets HG? High stability requirements in the 3258-2010-T industrial thiourea dioxide standard, and its thermal stability ≥ 60min. The thiourea dioxide crystal product produced by the invention has the advantages of concentrated particle size distribution, crystalline luster on the surface, high purity, good thermal stability, etc., can effectively improve the quality of the thiourea dioxide product, improve the safety performance of its transportation and storage, and prolong the shelf life of its product.

Description

technical field [0001] The invention belongs to the technical field of industrial crystallization, and in particular relates to a method for extending the shelf life of thiourea dioxide products. Background technique [0002] Thioureadioxide (TD for short) is a new, environmentally friendly and powerful reducing agent that can replace sodium hydrosulfite. Its reducing ability is 5 times that of hydrosulfite, and it has non-toxic, tasteless, good stability, safe transportation, and high reduction potential. Advantages, it is widely used in textile, paper, photosensitive materials, cosmetics and other industrial fields. In recent years, its application in organic synthesis and analysis, medicine, spices and precious metal recovery and separation has also been continuously developed. At present, the annual demand for thiourea dioxide is about 200,000 tons. Although the production scale of my country's thiourea dioxide enterprises (accounting for about 70% of the world's total ...

AI Technical Summary

Problems solved by technology

Since the reaction rate of hydrogen peroxide oxidizing thiourea in the water phase is very fast and the heat of reaction is very large, the temperature of the reaction system is difficult to control, resulting in a fast reaction crystallization rate of thiourea dioxide and uneven local supersaturation. The crystal particle size of thiourea dioxide product is small, the particle size distribution is uneven, the crystal surface is rough, and it is easy to coalesce and contain the crystallization mother liquor, so that the residual reaction raw materials (hydrogen peroxide, thiourea) and side reaction impurities in thiourea dioxide product are relatively high.

The thiourea dioxide product with small particle size, uneven distribution and rough surface has a large specific surface area, which makes it easier to absorb moisture, while the residual hydrogen peroxide and thiourea in the product will undergo deep oxidation in the presence of water, and the large amount of heat generated by the reaction will also Decompose thiourea dioxide to generate sulfur, which makes the product prone to yellowing and quality degradation during storage and transportation.