A metal leaching recovery method for continuous multi-stage extraction

Abstract

The invention discloses a metal leaching recovery method of continuous multi-stage extraction. Metal leaching is carried out on fly ash with hydrochloric acid, and 5‑salicylaldoxime (LIX860N‑I) and mixed trialkylphosphine oxide (Cyanex 923) are used as recovery fly ash. Ash and other heavy metal-rich wastes are used as extraction agents for heavy metals, kerosene is used as the solvent of the extraction agent, sulfuric acid, pure water and potassium chloride are used as stripping agents, and the multi-stage extraction method of adding different extraction agents and stripping agents step by step, combined The selectivity of the extractant, the sequential addition of two types of extractant can achieve the maximum degree of step-by-step separation of copper, cadmium, zinc and iron metals in the acid leaching solution, effectively reducing the secondary purification of metal mixed compounds with similar chemical properties The cost; the extraction process proposed by the present invention has the advantages of simplicity, quickness, and low cost, and can provide a new idea for resource utilization of metals in fly ash.

Description

technical field [0001] The invention relates to the technical fields of environmental chemistry and environmental engineering, in particular to a multi-stage extraction method with the characteristics of low cost and high efficiency for copper, cadmium, zinc, iron and other metals in wastes rich in heavy metals such as fly ash. Background technique [0002] Fly ash is the main solid waste produced in the waste incineration process. In the process of waste incineration, heavy metals (such as copper, zinc, lead, cadmium, etc.) often exist in the incineration products (such as bottom ash, fly ash, etc.) in the form of metal elements or oxides, and are released with the flue gas. Directly landfilling fly ash or mixing it with concrete construction means the loss of heavy metals in fly ash and the waste of metal extractable raw materials. Moreover, due to the large output of fly ash and its characteristics of less particles, direct stacking will form dust and block rivers. After...

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Problems solved by technology

[0004] 1. The metal recovery products (such as copper-zinc mixture) obtained by extraction are mixed metal compounds with very similar chemical properties. Because of the similar chemical properties in the recovered products, there are often phenomena such as isomorphic replacement or dense symbiosis, and it is difficult to dissociate the monomers. However, subsequent separation difficulties will lead to an increase in the actual utilization cost of recovered products, which is not conducive to the promotion of large-scale engineering applications;

[0005] 2. After the extraction process, the operation method of heating the extract phase to distill and separate it has high energy consumption. When it is used for the separation of various ions, there will be poor quality of recovered products, and the filtration operation will increase the loss of samples;

[0006] 3. When extracting the sample, because the extractant (such as bis-(2-hexylhexyl) phosphate) has a co-extraction effect on non-target metals, the recovered product is a mixed compound of various metals, which enhances the interaction of metal compounds , increasing the physical and chemical properties of recovered products, limiting the subsequent application range of metal compounds

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