A kind of method for extracting calcium without saponification

Abstract

The invention belongs to the field of hydrometallurgy, and discloses a method for extracting calcium without saponification, comprising the following steps: (1) adjusting the pH of a calcium-containing aqueous phase to 3.0-5.5; Phosphate, tributyl phosphate and diluent are made into an organic phase, and then the organic phase and the calcium-containing aqueous phase are mixed in a volume ratio of 1:0.5-4, and then extracted, and then the aqueous phase is separated to obtain a calcium ion-containing aqueous phase. The organic phase. The combined extractant of the invention has high extraction rate and good selectivity for calcium, and the single-stage extraction rate can reach more than 90%; the calcium in the water phase can be reduced from 600 mg / L to less than 1 mg / L after four-stage countercurrent extraction, 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 represented as Ca 2+ into the solution together with the valuable metals, Ca 2+ The existence of it will seriously affect the product quality. Contains a lot of Ca 2+ In the process of heating, cooling and transportation, calcium carbonate, calcium sulfate and other precipitates are easily produced, which adhere to the wall of the equipment and deposit scale, resulting in the decrease of the fluid flow rate in the pipe, the corrosion of the equipment, and the reduction of 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 problems such as ...

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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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