A kind of method of film crystallization refining coking crude ammonium sulfate

Abstract

The invention relates to a method for refining coking crude ammonium sulfate by membrane crystallization. The technical solution is: the pretreated coking crude ammonium sulfate crystallization mother liquor is fed into the membrane module, and the water in the mother liquor passes through the membrane in the form of water vapor through membrane distillation and is condensed into liquid water on the other side of the membrane, leaving The crystallization mother liquor of the membrane module is concentrated to supersaturation and then sent to the crystallizer, the crystals are fluidized and suspended in the circulating crystallization mother liquor, the crystallization mother liquor on the upper layer of the crystallizer is pumped into the membrane module for internal circulation, and the crystallization product is drawn out from the lower part of the crystallizer. Solid-liquid separation and drying to obtain ammonium sulfate crystals. The present invention uses membrane distillation to evaporate and concentrate the ammonium sulfate crystallization mother liquor to achieve supersaturation, and the crystal growth is located in the fluidized bed crystallizer, which provides better conditions for crystal growth, and the fluidized bed crystallizer has both particle size classification, so that the growth The ammonium sulfate crystal product has a large and uniform particle size. The invention can also effectively reduce the production cost of ammonium sulfate recrystallization and refinement.

Description

technical field [0001] The invention belongs to the technical field of metallurgy, coking and chemical industry, and in particular relates to a method for refining coking crude ammonium sulfate by membrane crystallization. Background technique [0002] Coking ammonium sulfate is a large industrial by-product of coke oven gas purification. my country's coke output ranks first in the world, and the domestic coking ammonium sulfate output is huge. Ammonium sulfate is an important nitrogen fertilizer, and it can also be used as a printing and dyeing agent, a food catalyst, and a leather deliming agent in industry. [0003] Domestic coking ammonium sulfate is mostly produced by the saturator method. Because of the influence of impurities, it is often gray, green, blue, dark black or red. The particle size does not exceed 0.5mm; and the moisture and acidity exceed the standard. Ammonium sulfate crystals are easy to absorb moisture and agglomerate, especially when the air humidi...

AI Technical Summary

Problems solved by technology

There is a temperature difference between the crystallization mother liquid surface and the main body area of ​​the mother liquid (or the heat exchange surface and the main body area of ​​the mother liquid during the cooling and crystallization process) during the evaporation crystallization process, which causes a temperature gradient in the mother liquid during the evaporation crystallization (or cooling crystallization) process, and the degree of supersaturation is not uniform. The grown crystals are not uniform in size