Self recycling method of waste water in rare earth carbonate precipitation

Abstract

The invention relates to a self recycling method of waste water in rare earth carbonate precipitation, which belongs to the field of rare earth hydrometallurgy. The method comprises the following steps: part of mother liquor, which is generated in the rare earth carbonate precipitation production process, is directly transmitted into a rare earth carbonate recycling pool to be clarified, and concentrating and crystallization equipment is used for recyling ammonium chloride or sodium chloride; the rest of the mother liquor is transmitted into a mother liquor storage tank, and is used for adjusting the concentration of carbonate precipitation liquor and dissolving the precipitant; the rare earth carbonate precipitate is washed in a reverse flow mode to obtain a first filtrate; the first filtrate and the mother liquor are recycled to the rare earth carbonate precipitation technique to dissolve the precipitant and dilute the liquor; and the residual waste water after recycling is concentrated and crystallized to recycle ammonium chloride or sodium chloride. The precipitation waste water is recycled, thereby reducing waste water discharge amount and the consumption of new water, increasing the concentration of ammonium chloride or sodium chloride in waste water and lowering the energy consumption for concentration and crystallization.

Description

technical field [0001] The invention relates to a method for self-recycling of rare earth carbonate precipitation wastewater, which belongs to the field of rare earth hydrometallurgy. Background technique [0002] In industrial production, ammonium bicarbonate and sodium carbonate are mainly used as precipitants for rare earth carbonate, and the pH value of the mother liquor after precipitation is both 7; Contains ammonium chloride, the mother liquor and filtrate are concentrated and crystallized to recover ammonium chloride, ammonium chloride is mainly used to prepare agricultural fertilizers; sodium carbonate solution is used as the precipitant, the mother liquor after precipitation and the filtrate of washing rare earth carbonate contain sodium chloride, The mother liquor and filtrate are concentrated and crystallized to recover sodium chloride, and sodium chloride is prepared by electrolysis to prepare sodium hydroxide and hydrochloric acid. [0003] Ammonium bicarbonat...

AI Technical Summary

Problems solved by technology

[0003] Ammonium bicarbonate has low price and large output. It has been widely used in the rare earth industry since the 1990s. The concentration of ammonium chloride in the rare earth carbonate precipitation mother liquor is relatively high. It can be concentrated and crystallized by multi-effect falling film or heat transfer oil heating equipment. Recovering ammonium chloride, rare earth carbonate entrains or adsorbs certain chloride ions and ammonium ions in the precipitation process. In order to prepare pure rare earth carbonate, a large amount of new water is required for multiple cross-flow washing to wash off these ions, and the washing of rare earth carbonate The ammonium chloride concentration in the filtrate decreases with the increase of the number of washes. After the first washing, the ammonium chloride concentration in the filtrate is lower than that of the mother liquor. After the second washing, the ammonium chloride concentration in the filtrate is lower than that of the first filtrate. After multiple washings, the ammonium chloride content in the filtrate is very low. These filtrates cannot be directly recovered by simple concentration and crystallization processes like the mother liquor, and cannot be discharged directly. This problem has always plagued the development of enterprises, (patent: CN101088935A And CN1331055A) high-concentration ammonium salt waste water is reclaimed ammonium chloride with concentration method, and low-concentration ammonium salt waste water adopts air stripping method to prepare ammoniacal liquor, but low-concentration ammonium salt waste water produces a large amount, and air stripping method needs equipment big, and the energy consumption is big, High cost, unacceptable for enterprises

Sodium carbonate is used as a precipitant to prepare rare earth carbonate. Although the wastewater does not contain ammonia nitrogen, it contains sodium chloride. If it is discharged, it will also pollute the environment.

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