Sodium sulfide continuous cooling crystallization system and process

Abstract

The invention relates to a sodium sulfide continuous cooling crystallization system and process. After being heated and concentrated, a sodium sulfide solution is input into a plate heat exchanger through a feeding pump and is pre-cooled; the pre-cooled feed liquid enters a circulating pipeline consisting of a heat exchanger and a crystallizer, undergoes continuous cooling crystallization under the action of a circulating pump in the circulating pipeline, and undergoes cooling crystallization to obtain Na2S-5.5H2O crystal slurry; and the obtained crystal slurry is discharged through a discharging pump, is conveyed to a crystal slurry tank for temporary storage, then is input into a centrifugal machine through a crystal slurry pump, and undergoes solid-liquid separation. The sodium sulfidesolution is evaporated and concentrated to reach a certain temperature and concentration, and high-purity white Na2S-5.5H2O crystals are obtained through the continuous cooling crystallization system,so that the defects of high impurity content, serious equipment corrosion and the like of the conventional flaky sodium sulfide product are overcome; and the continuous cooling crystallization process is adopted to replace intermittent crystallization operation of cooling in the kettle, and the continuous cooling crystallization process has stable feeding, discharging and cooling processes, so that the personal health of operators is greatly improved.

Description

technical field [0001] The invention belongs to the technical field of sodium sulfide crystallization production, and in particular relates to a sodium sulfide continuous cooling crystallization system and a process thereof. Background technique [0002] At present, the main domestic production of sodium sulfide is coal powder reduction mirabilite method and the production of precipitated barium sulfate by-product sodium sulfide, industrial sodium sulfide products mainly contain Na 2 Red barrel soda, protopine and yellow protopine with a mass fraction of S of 60% have a single variety and high impurity content, which are far from meeting the requirements of high-level tanning, medicine, food and other industries. [0003] In recent years, people have begun to pay attention to the research of high-purity sodium sulfide crystals with low impurity content. The preparation method of sodium sulfide adopted in the production method of public CN1944241A high-purity crystalline sod...

AI Technical Summary

Problems solved by technology

The preparation method of sodium sulfide adopted in the production method of public CN1944241A high-purity crystalline sodium sulfide is complicated, and the process produces toxic gas H 2 S, is unfavorable for the health of operating workers; in the CN101823701A high-purity white crystalline sodium sulfide process, impurities are mainly removed by adding reagents, the steps are cumbersome, and new impurities may be introduced. The sodium sulfide content is 52%-60%, which is harmful to equipment materials High standard

[0004] The development of the continuous crystallization process of sodium sulfide crystals has not been reported in China. The production of sodium sulfide in enterprises generally adopts the intermittent cooling crystallization method. Heat exchange; fouling needs to be cleaned after batch production to reduce production efficiency

[0005] Alkali sulfide is a toxic substance that will cause burns when it comes into contact with skin and hair. It is easily oxidized in the air. The main oxidation product is sodium thiosulfate. Therefore, intermittent operation will cause physical injury to the operator and affect the quality of the product

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