Process method for recovering ammonium chloride and sodium chloride from waste water containing ammonium chloride and sodium chloride

Abstract

The invention relates to a process method for recovering ammonium chloride and sodium chloride from waste water containing the ammonium chloride and the sodium chloride, which produces the ammonium chloride and the sodium chloride by using mother solution which is generated in a process for producing sodium bicarbonate by natural bittern double decomposition reaction and contains the ammonium chloride and the sodium chloride as raw materials. The method adopts ammonium still, evaporation, crystallization and separation process to treat, wherein the evaporation adopts multiple-effect, a heat pump and a vacuum evaporation process, and selects a falling film evaporator and a forced circulation type evaporator to perform triple-effect mixed-flow procedure, so that sodium chloride is crystallized and separated in the evaporation; and the ammonium chloride is crystallized and separated by cooling after the evaporation. The method effectively reduces the operation temperature of the equipment, can repeatedly use secondary steam and condensed water, reduces erosion of the ammonium chloride solution to the equipment, saves the energy, reduces the cost, improves the production efficiency, and reduces environmental pollution.

Description

technical field [0001] The invention relates to a process for recovering ammonium chloride and sodium chloride from waste water containing ammonium chloride and sodium chloride. The mother liquor is used as raw material to produce ammonium chloride and sodium chloride. Background technique [0002] The natural brine method utilizes metathesis reaction to produce baking soda. During the production process, a large amount of high-concentration ammonium chloride mother liquor will be discharged. Most enterprises directly discharge the mother liquor into rivers with wastewater without treatment, which not only wastes resources, but also causes serious pollution to the environment. Recovering ammonium chloride and sodium chloride from double decomposition baking soda mother liquor can turn waste into wealth and protect the environment. The treatment method of ammonium chloride filtered mother liquor in the soda ash industry by combined alkali method generally adopts the "cold me...

AI Technical Summary

Problems solved by technology

However, there are two major difficulties in the production of this method: one is that a large amount of water must be evaporated to recover ammonium chloride and sodium chloride, and the energy consumption is large and the cost is high; the other is that the ammonium chloride solution produces extremely strong corrosion to the equipment, Even if expensive titanium is used, there are still corrosion problems in the equipment under the condition of high temperature and high concentration

[0003] Chinese patent CN101244829A discloses reclaiming ammonium chloride and sodium chloride from the soda-making mother liquor, and its evaporation has adopted vacuum multi-effect countercurrent evaporation, but its energy consumption is still relatively high, and the separation of sodium chloride from the first effect is due to the higher temperature The centrifuge is highly corroded, and there is no report on its industrialization success.

[0004] Chinese patent CN1084298C reports the recovery of ammonium chloride from the waste liquid containing ammonium chloride, which has a wide range of applications. Its evaporation adopts vacuum multi-effect falling film evaporation, which solves the problems of corrosion and energy consumption, but this method is applied to chlorine-containing It is not suitable for the waste liquid recovery of ammonium chloride and sodium chloride, because it does not involve the recovery of sodium chloride

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