Method of extracting calcium without saponification

Abstract

The invention belongs to the field of hydrometallurgy and discloses a method of extracting calcium without saponification. The method comprises the following steps of (1) adjusting the pH of a calcium-containing water phase to 3.0-5.5; and (2) preparing an organic phase from bi(2-ethylhexyl) phosphate, tributyl phosphate and a diluent, then mixing the organic phase with the calcium-containing water phase in a volume ratio of 1: (0.5-4), then carrying out extraction, and separating a water phase to obtain the organic phase containing calcium ions. A combining extractant is high in extraction rate of calcium and good in selectivity, and the single-stage extraction rate can reach over 90%. Calcium in the water phase after four-stage counter-current extraction can be decreased from 600 mg / L to1 mg / L, and the extraction rate can reach 99.8%.

Description

technical field [0001] The invention relates to the field of hydrometallurgy, in particular to a method for extracting calcium without saponification. Background technique [0002] In hydrometallurgy, when metal minerals are leached with acidic solutions, calcium is usually expressed as Ca 2+ into solution together with valuable metals, Ca 2+ The existence of will seriously affect the product quality. Contains a lot of Ca 2+ Calcium carbonate, calcium sulfate and other precipitates are likely to be produced during heating, cooling and transportation of high-grade industrial production water, which adhere to the equipment wall to deposit and scale, resulting in a decrease in the fluid flow rate in the pipe, corrosion of the equipment, and a reduction in production capacity. [0003] Commonly used in industry to remove Ca 2+ Methods include chemical precipitation, adsorption, membrane separation, ion exchange and extraction. Among them, the precipitation method has proble...

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Problems solved by technology

Among them, the precipitation method has problems such as incomplete calcium removal, cumbersome operation, easy adsorption of metals by precipitation, and environmental pollution caused by filter residue stacking; the adsorption method has the advantages of strong selectivity and simple operation, but has the problem of insufficient adsorption capacity, and the adsorption There are few studies on how to regenerate the agent; the membrane separation method removes Ca 2+ Simple operation, high efficiency and energy saving, no phase change, and good selectivity, but the surface of the membrane is easily polluted, resulting in a decrease in the separation effect, and the membrane needs to be cleaned regularly, which increases a certain maintenance cost. The heat resistance, chemical resistance, and solvent resistance of the membrane However, the extraction method can be operated continuously, and has the advantages of large processing capacity, strong selectivity, high extraction rate, and the extraction agent can be recycled and recycled. It has become an industrial production method at home and abroad. The main method of calcium removal

[0004] There are many research reports on the removal of calcium by solvent extraction: In the process of preparing high-purity strontium carbonate, Li Kun et al. used D2EHPA (di-(2-hexylhexyl) phosphoric acid) as the extraction agent and sulfonated kerosene as the diluent to investigate the extraction equilibrium. The influence of time, diluent, equilibrium pH value, temperature, aqueous phase calcium ion concentration, extractant concentration and other factors on calcium extraction rate, in the solution after crude strontium carbonate hydrochloric acid leaching and removal of barium and iron impurities, D2EHPA-sulfonate The primary extraction rate of calcium in the kerosene system is 46.11%, and the saturated extraction rate is 83%. However, the defect of this method is that the extraction rate is low and it is not suitable for precise extraction; Extraction of low concentration calcium (Ca 2+ Concentration 16.3mg / L), investigated the influence factor that calcium ion removes, with 10%P204+90%260# kerosene as organic phase, saponification with NaOH, saponification rate is 35%, in aqueous phase pH=5.0, Vo:Va (Volume ratio of organic phase to calcium-containing aqueous phase) = 1:2, extraction time 3min and temperature 25°C, Ca 2+ The single-stage extraction rate is 80%, after 3-stage countercurrent extraction, Ca 2+ The concentration is reduced to below 1mg / L, which meets the requirements for the production of high-quality cobalt sulfate and nickel sulfate products. 2+ Requirements, but adding NaOH saponification will produce sodium ions and affect the quality of the product

Moreover, the saponification process is likely to bring environmental pollution, cost increase and impurity increase and other adverse factors

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