Heavy metal chelating agent for waste incineration fly ashes and preparation method for heavy metal chelating agent

Abstract

The invention discloses a heavy metal chelating agent for waste incineration fly ashes. The heavy metal chelating agent for the waste incineration fly ashes comprises a compound chelating agent and a sodium hydroxide solution mixed with a weight ratio being 1:2-3, wherein the compound chelating agent comprises, by weight percentage, 60-90% of an organic chelating agent, and 10-40% of an inorganic chelating agent, the organic chelating agent is dithiocarbamates and is one or more selected from zinc diethyl dithiocarbamate, zinc dimethyl dithiocarbamate, sodium dibutyl dithiocarbamate or sodium dibenzyl dithiocarbamate, and the inorganic chelating agent is one or two selected from sodium sulfide and sodium phosphate. The heavy metal chelating agent for the waste incineration fly ashes is capable of reducing the leaching concentration of heavy metals and ensuring that a fly ash solidification sample block can meet the limit value of the leaching concentration. The invention further provides a preparation method for the heavy metal chelating agent for the waste incineration fly ashes.

Description

[0001] 【Technical field】 [0002] The invention relates to the technical field of metal chelating agents, in particular to a waste incineration fly ash heavy metal chelating agent and a preparation method thereof. [0003] 【Background technique】 [0004] The fly ash of domestic waste incineration has complex components, and the main pollutants are heavy metals with high leaching toxicity, which have serious harm to the environment. Heavy metals are constantly migrating and transforming in the environment. The polluted soil and water environment cannot be eliminated through its own purification, and cannot be decomposed by microorganisms, and will be enriched through the biological chain. Therefore, improper handling of fly ash will lead to pollutants in it The loss of heavy metals into the environment will cause serious harm to human health and the natural environment. After testing, the fly ash of domestic waste incineration contains heavy metals with high leaching concentrat...

AI Technical Summary

Problems solved by technology

[0005] At present, there are three main treatment methods for heavy metal components in fly ash. One is to use cement solidification technology to solidify heavy metals. Heavy metals react with cement through ion exchange, passivation, adsorption, chemical adsorption, sedimentation and hydration. On the surface of the hydrated silicate colloid C-H-S, relatively stable compounds such as hydroxide or complexes are formed, but this method has the disadvantages of increasing the capacity of fly ash and increasing the volume of landfill; the second is the melting and solidification method, This method is currently recognized as the safest and most stable incineration fly ash stabilization / solidification technology. This method is mainly to mix incineration fly ash and glassy powder into granules, and melt them at a high temperature of 1000-1400 °C for a period of time. This method has the disadvantage of high energy consumption; the third is the chemical agent stabilization method. Chemical agents transform their ions into low-solubility, low-mobility polymer complexes or inorganic minerals through chemical reactions with heavy metals. The selection of chemical chelating agents, especially the selectivity of chemical agents to the main polluting heavy metal ions, and the stability of complexes, especially the leaching properties of acidic solutions; Most of the mixtures are DTC chelating agents (dithiocarbamate referred to as DTC), which belong to non-polymer compounds, contain less complexing centers per unit molecular weight, and the complexes formed with heavy metals can have a high leachable concentration

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