Balanced circulating mother liquor purification method based on evaporation salt making system

Abstract

The invention discloses a balanced circulating mother liquor purification method based on an evaporation salt making system. Three stages of evaporation are adopted for mother liquor of the salt making system, a high-purity sodium nitrate intermediate product is produced, sodium sulfate and sodium chloride are separated out by crystallization, the high-temperature mother liquor is conveyed back to the evaporation salt making system for continuous circulating balance, sodium nitrate circulating mother liquor circulates, and sodium nitrate circulating mother liquid components are balanced by adding fresh water and discharging the mother liquor. Three stages of evaporation are adopted for the salt making system, the sodium nitrate circulating mother liquor components are balanced by adding the fresh water and discharging the fresh water, in this way, discharging of three wastes does not exist, product quality is high, the utilization rate of raw materials is high, reaction time is obviously shortened, equipment investment and process operating cost are saved, the total steam consumption is lowered by 20% or above per ton of sodium nitrate, energy is saved, environmental protection is achieved, flashing intensity can be reduced, the production period can be effectively prolonged, the utilization rate of heat energy can be increased, and system productivity can be improved. Meanwhile, the method has the advantages of being high in purification efficiency and low in energy consumption.

Description

technical field [0001] The present invention relates to IPC classification C01D9 / 00 sodium, potassium or general alkali metal nitrate process and equipment, or IPC classification C01D9 / 16 purification technology, especially a method for purifying balanced circulation mother liquor based on evaporation salt production system. Background technique [0002] Sodium nitrate has a melting point of 306.8°C and a density of 2.257 g / cubic centimeter (at 20°C). It is a colorless transparent or white slightly yellow rhombic crystal. It tastes bitter and salty, easily soluble in water and liquid ammonia, slightly soluble in glycerin and ethanol, and easy to deliquescence, especially when it contains a very small amount of sodium chloride impurity, the deliquescence of sodium nitrate will be greatly increased. When dissolved in water, the solution temperature decreases and the solution is neutral. When heated, sodium nitrate is easily decomposed into sodium nitrite and oxygen. [0003]...

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Problems solved by technology

[0005] For sodium sulfate well mine salt, the domestic salt industry mostly adopts the salt and nitrate cogeneration process of the four-effect vacuum evaporation salt production heat method to extract nitrate. Due to the limitation of the heat pump compression ratio, the heat transfer evaporation capaci

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