A new process for preparing sodium thiocyanate

Abstract

The invention belongs to the technical field of chemical engineering and discloses a new process for preparing sodium thiocyanate. The new process for preparing sodium thiocyanate comprises that coked gas PDS process desulphurized mixed salt is taken as a raw material, firstly sodium thiocyanate inside the raw material is extracted with methyl alcohol, then filter pressing is carried out, so that sodium thiocyanate filtrate is obtained, and finally evaporation concentration, cooling crystallization and centrifugal drying are carried out, so that sodium thiocyanate crystals are obtained. Sodium thiocyanate prepared by adopting the new process disclosed by the invention has high purity and good market prospect, desulphurization waste is effectively utilized, a waste material is changed into things of value, industrial raw material cost is greatly reduced, and occupying area is also reduced to some extent, so that an enterprise can make up the deficits and get surpluses.

Description

technical field [0001] The invention belongs to the technical field of chemical industry and relates to a new process for preparing sodium thiocyanate. Background technique [0002] Sodium thiocyanate is a white orthorhombic crystal or powder, which is easy to deliquescence in the air and produces toxic gas when it encounters acid. It is easily soluble in water, ethanol, acetone and other solvents; its aqueous solution is neutral, and it will form blood-colored thiocyanate with iron salt. Ferrous chloride, does not react with ferrous salts, produces yellow sodium bisulfate with concentrated sulfuric acid, reacts with cobalt salts to form dark blue cobalt thiocyanate, and reacts with silver or copper salts to form white silver thiocyanate precipitates or black precipitation of copper thiocyanide. Sodium thiocyanate can be used as acrylic fiber spinning solvent, chemical analysis reagent, color film film flushing agent, some plant defoliants and airport road herbicides, also ...

AI Technical Summary

Problems solved by technology

The accumulation of these by-products will increase the viscosity of the desulfurization liquid and greatly reduce the desulfurization efficiency. Therefore, coking enterprises will regularly discharge part of the waste liquid. If it is not utilized, it will be discharged as industrial waste, which will inevitably pollute the environment.

At present, the total amount of desulfurization waste liquid discharged by domestic coking enterprises is more than 1 million tons. Most of them are discharged directly without treatment, or mixed with coking coal for incineration, which seriously pollutes the air and water resources. Only a small part of the desulfurized liquid is treated.

There are many methods used for the treatment of desulfurization waste liquid at home and abroad. The most researched and applied methods are ammonia method, water phase method and chemical method. However, the above methods have many defects. For example, the water phase method produces The sodium thiocyanate product has low purity, poor quality, low price, and serious losses for enterprises. The chemical method uses a variety of chemical reagents, the cost of raw materials is high, and it is easy to cause secondary pollution; Not taking the initiative to invest funds in the treatment of desulfurization waste liquid, which is the root cause of the inability to eliminate environmental pollution

[0004] At present, many domestic gas or coking enterprises adopt the ammonia method (or alkali method) gas desulfurization process, because the desulfurization waste liquid contains thiocyanate ions, which have a strong bactericidal effect and cannot be biochemically treated

If it is not treated and discharged directly, it will cause water pollution and poor production site environment; if it is used as coal blending water, it will still cause secondary pollution and increase operating costs

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