Treatment method of thiourea feed liquid

Abstract

The invention provides a treatment method of thiourea feed liquid. The treatment method comprises the following steps that a resin column is filled with SH-type anion resin, the resin is used for conducting ion exchange with the thiourea feed liquid, and the treated thiourea feed liquid is obtained. Compared with the prior art, according to the provided treatment method, a specific kind of ion exchange resin is selected to conduct the ion exchange for the thiourea feed liquid, thus thiocyanate ions enter into the resin, meanwhile HS<-> ions are displaced, in the process of thiourea production,HS<-> participates in the reaction, thus the thiocyanate ions in the thiourea feed liquid can be effectively removed without damaging the thiourea feed liquid and affecting the recycling use of the thiourea feed liquid, the content of the thiocyanate ions in a thiourea product is further significantly decreased, and the product quality is improved. The experimental result shows that the thiocyanate content in the treated thiourea feed solution obtained by the provided treatment method does not exceed 1.33%, the thiocyanate content in the obtained thiourea product does not exceed 0.013%, and the requirements of the product quality standard are met.

Description

technical field [0001] The invention relates to the technical field of chemical production, in particular to a method for treating thiourea feed liquid. Background technique [0002] Thiourea, the molecular formula is (NH2)2CS, the relative molecular mass is 76.12, white rhombus or needle-like bright crystal; flammable, melting point 170℃~180℃, high temperature decomposition; soluble in cold water and ethanol, almost insoluble in ether. At present, water, lime nitrogen (calcium cyanamide) and hydrogen sulfide gas are used as raw materials in the industry, and the absorption synthesis reaction is carried out in the synthesis kettle to obtain a solution containing thiourea. After the solution is filtered and purified for many times, it is cooled and crystallized. , After the solid-liquid separation, the crystals are centrifuged and dried, and then the finished product is obtained by drying, and the mother liquor obtained by centrifugation is returned to the system for recyclin...

AI Technical Summary

Problems solved by technology

In the synthesis reaction of thiourea, the reaction temperature is 85°C. At this time, a large amount of thiourea is converted into ammonium thiocyanate. Ammonium thiocyanate is easily soluble in water. With the recycling of thiourea feed liquid, the Thiocyanate content accumulates gradually, will eventually cause the content of thiocyanate in the thiourea product to exceed the index requirement (indicator requirement: thiocyanate≤0.02%), the thiourea feed liquid contains more than 12% thiourea, if the feed liquid cannot Recycling will not only cause economic losses but also cause environmental pollution, so it is necessary to find a way to remove thiocyanate in the thiourea feed solution

[0004] At present, due to the complexity of the thiourea feed liquid system, there are sulfate radicals, thiosulfate radicals, and sulfhydryl ions, and there is no suitable treatment method for the thiourea feed liquid in the prior art, that is, no processing is performed; Concentrate the system after a certain amount, and crystallize to obtain some thiourea products (the recovery rate of thiourea is about 60%), and the remaining feed liquid is treated as waste water