Production process for extracting mirabilite by continuous salting-out hot process

Abstract

The invention discloses a production process for extracting mirabilite by a continuous salting-out hot process and belongs to the technical field of salt-mirabilite coproduction. The production process comprises the following steps that three-stage counter-flow emulsification float washing is carried out on raw materials including brine and salt slurry in a salt washer, centrifugal dewatering anddrying are carried out on washed salt slurry is directly dewatered and dried centrifugally and then is packaged into finished salt, the discharged overflowing liquid and a little amount of mother liquor discharged from an evaporation tank enter a mother-liquor transferring barrel together, then after multi-stage preheating (the preheating heat source is all-effect residual condensate), the mother-liquor transferring barrel is conveyed into a crystallizer, the temperature is increased to 95-100 DEG C, simultaneously NaCl is added by 2%-4% of the solid content in the mother liquor, and the mirabilite is crystallized and precipitated according to the principle of common ion effect, then is taken out of the system, dewatered and dried to obtain a mirabilite product. The production process disclosed by the invention has the advantages of low steam consumption, low production cost, simple technological process, less equipment investment, simple operation and continuous and controllable production.

Description

technical field [0001] The invention relates to the technical field of combined production of salt and nitrate, in particular to a production process for extracting nitrate by a continuous salting-out thermal method. Background technique [0002] The type of brine in the main salt-producing areas in my country is sodium sulfate type. In addition to the main content of sodium chloride, the average content of secondary content of sodium sulfate is as high as 25g / l or more. In addition, it also contains a small amount of calcium sulfate and magnesium sulfate. The salt production process of this type of brine generally adopts the combined production process of salt and nitrate, in which salt and nitrate are crystallized from the system respectively. In order to control the salt quality and ensure that Glauber’s salt does not crystallize out in the salt system, it is necessary to discharge a large amount of mother liquor in the tank, resulting in huge heat loss. Therefore, the st...

AI Technical Summary

Problems solved by technology

Although the product quality can be guaranteed, the investment in equipment and equipment is large, the process route is complicated, and the operation control is difficult. Among them, the cost of brine purification is more than 10 yuan per ton of product, and the steam consumption per ton of product is more than 1.1, which is economically uneconomical.

b. Poor process adaptability: There is also a very fatal flaw in the salt and nitrate co-production process, that is, poor process adaptability

When the composition of raw brine changes, especially when the content of sodium sulfate suddenly rises, due to the solidification design of the system, once the discharge of mother liquor increases, it will inevitably lead to an imbalance of heat and materials, resulting in a sharp drop in salt production, and some mother liquor It must be discharged from the system, resulting in non-compliance in environmental protection; if the discharge is not increased, sodium sulfate will crystallize out in the salt system, affecting product quality

Images