Calcium fluoride (CaF2) induction crystallization process from rare-earth metal smelting high-fluoride wastewater

Abstract

The invention discloses a calcium fluoride (CaF2) induction crystallization process from rare-earth metal smelting high-fluoride wastewater. The fluidized bed crystallization is used; meanwhile, an electromagnetic field is exerted; under the helium gas atmosphere, through the coupling effect of the fluidized bed crystallization, the electromagnetic field and the helium gas, the crystallization dynamics process parameters such as the crystallization bed process, flow rate, temperature and the like are controlled, so that the CaF2 crystallization velocity is accelerated; the efficient crystallization is realized; the high-purity CaF2 is obtained; the fluorine deep removal and the CaF2 resource recovery are also realized.

Description

technical field [0001] The invention relates to a technique for inducing crystallization of calcium fluoride in rare earth metal smelting high-fluorine wastewater, which belongs to the field of wastewater treatment. Background technique [0002] South Jiangxi is rich in rare metal mineral resources. At the same time, most of the tantalum, niobium, tungsten and some rare earth smelting enterprises in this area also produce a large amount of high-fluorine wastewater, and its fluorine content is generally 1.2-3.2g / L, exceeding the standard by 120-320 times. Fluorine-containing wastewater is the most harmful wastewater produced in the rare metal smelting process, the most complex in nature, and the most difficult to treat. It is a difficult problem that needs to be solved urgently. In fact, the low-cost and effective method for removing fluoride from rare metal smelting wastewater is still the calcium precipitation method. but chemically precipitated CaF 2 It is not just a che...

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Problems solved by technology

However, the solubility of lime is low, so it can only be added in the form of emulsion, and the produced CaF 2 Precipitate wrapped in Ca(OH) 2 The surface of the particles prevents them from being fully reacted, and the actual amount is much greater than the theoretical amount

CaF 2 It has colloidal properties, slow settling, difficult solid-liquid separation, low purity, and difficult to recycle

The more important rare metal smelting wastewater has complex components and contains other substances that can increase CaF 2 Solubility ions and complex forms of fluoride that do not participate in the neutralization reaction exist. After treatment, the fluorine content in wastewater can only be reduced to 15mg / L. It is difficult to meet the national standard first-level discharge standard. Chemical precipitation and fluoride removal are facing great challenges.

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