Continuous multi-level extraction metal leaching recycling method

Abstract

The invention discloses a continuous multi-level extraction metal leaching recycling method. Metal leaching is conducted on fly ash through hydrochloric acid; 5-salicylaldoxime (LIX860N-I) and mixed trialkyl phosphine oxide (Cyanex 923) serve as extraction agents for recycling heavy metal in heavy metal waste, such as the fly ash, rich in the heavy metal; kerosene serves as solvent of the extraction agents; and sulfuric acid, pure water and potassium chloride serve as reverse extraction agents. The multi-level extraction method that different extraction agents and the reverse extraction agentsare added level by level is adopted; selectivity of the extraction agents is combined; the two types of extraction agents are sequentially added, and level-by-level separation of metallic copper, metallic cadmium, metallic zinc and metallic iron in pickle liquor can be achieved to the greatest extent; the cost of secondary purification conducted on mixed metal compounds similar in chemical property is effectively lowered; the extraction process has the advantages of being simple, fast and convenient to implement, low in cost and the like; and a new concept can be provided for resource utilization of the metal in the 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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