A recovery and utilization method for ammonium chloride MVR evaporative crystallization mother liquor

Abstract

A recovery and utilization method for ammonium chloride MVR evaporative crystallization mother liquor is provided. The method is used for recovering and utilizing the ammonium chloride MVR evaporativecrystallization mother liquor after a plurality of times of evaporation in an MVR circulating evaporative crystallization system. The method includes performing cooling and crystallization at 20-28 DEG C after the mother liquor is subjected to single-effect evaporation to obtain ammonium chloride MVR evaporative crystallization secondary mother liquor; adding ammonium bicarbonate solid into the secondary mother liquor at 35-40 DEG C to obtain sodium bicarbonate solid; dissolving the sodium bicarbonate solid with water; then adjusting the pH to 10-12; and removing ammonia nitrogen with a gas-sensitive degassing membrane to obtain a sodium carbonate solution. The method ensures cyclic operation of ammonium chloride MVR evaporative crystallization, and achieves recovery and utilization of asodium resource. The obtained sodium carbonate solution can be used for a copper carbonate production process, thus bringing economic benefit. The method is simple, easy to operate, low in cost and free of waste generation.

Description

technical field [0001] The invention relates to a method for recycling ammonium chloride MVR evaporation and crystallization mother liquor. Background technique [0002] Alkaline etching waste liquid and acidic etching waste liquid produced in the printed circuit board manufacturing process are recovered from heavy metal copper, and other heavy metals, organic matter, and sulfate radicals are removed to obtain ammonium chloride solution. The ammonium chloride solution uses MVR (Mechanical Vapor Recompression (mechanical vapor recompression) evaporation, cooling and crystallization to obtain ammonium chloride product. [0003] Then, the ammonium chloride MVR evaporative crystallization mother liquor returns to the ammonium chloride solution, and enters the MVR device for evaporation and concentration again, that is, the ammonium chloride MVR evaporative crystallization mother liquor will circulate in the evaporation and cooling crystallization process. After repeated evapora...

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Problems solved by technology

After repeated evaporation and crystallization, the content of sodium ions in the mother liquor of ammonium chloride MVR evaporation crystallization will increase, which in turn will increase the boiling point of the ammonium chloride solution by 4-8°C, causing problems such as a decrease in equipment evaporation and increased energy consumption.

[0004] Therefore, after the ammonium chloride solution has undergone multiple cycles of evaporation, cooling and crystallization, the ammonium chloride MVR evaporation mother liquor cannot be returned to the MVR evaporation system indefinitely.

At present, the mother liquor of ammonium chloride MVR evaporation and crystallization mainly adopts evaporation-drying technology to obtain mixed solid miscellaneous salt of ammonium chloride and sodium chloride. However, the solid miscellaneous salt has no reasonable way out and can only be temporarily sealed, which is extremely harmful to the environment. , and the recovery and utilization of ammonium chloride MVR evaporation and crystallization mother liquor is not yet a mature and effective technology, which needs to be solved urgently

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