Preparation method and application of heavy metal chelating agent

Abstract

The invention discloses a preparation method and application of a heavy metal chelating agent and belongs to the field of fly ash treatment. The chelating agent is prepared from dithiocarbamtes, weak acid salt, organic amine and water. The PH of a prepared chelating agent solution is smaller than 10.5, the chelating speed of the chelating agent solution and lead can be effectively increased, and the reaction speeds of the chelating agent solution and copper as well as the chelating agent solution and iron are properly decreased. Through the chelating agent, the influence of the high ammonia-nitrogen values of fly ash on the chelating capacity of the chelating agent can be effectively improved, and when the chelating agent is used in the sludge fly ash, the chelating capacity of the chelating agent is not lowered.

Description

technical field [0001] The invention relates to the field of fly ash treatment, in particular to a preparation method and application of a composite chelating agent for treating fly ash. Background technique [0002] The incineration of garbage produces a large amount of fly ash containing heavy metals, which greatly exceeds the sanitary landfill standard and becomes hazardous waste, which is extremely harmful to humans and the environment. Therefore, it is necessary to stabilize the heavy metals in the fly ash, so that it can meet the landfill standard or be used for subsequent resource utilization. [0003] At present, my country's waste incineration power plants basically purchase ammonia water or urea SNCR denitrification technology. The actual denitrification rate of the power plant is about 50%, which is controlled by the NOX emission index. On the one hand, a large amount of excessive ammonia is adsorbed in the pore structure of fly ash; on the other hand, excessive a...

AI Technical Summary

Problems solved by technology

However, inorganic phosphate chelating agents cannot meet the requirements of GB16889-2008 "Standards for Pollution Control of Domestic Waste Landfill Sites"; pure sodium dimethyl dithiocarbamate chelating agents are effective in treating incineration sludge fly ash and high ammonia nitrogen concentration fly ash Poor and high dosage; trisodium thiocyanate chelating agent has a deviation in the effect on nickel and has a deviation in the relative chelating ability of heavy metals compared with sodium dithiocarbamate, and the cost of the agent is relatively high; sodium polythiocarbonate chelating agent Poor mixture stability

Moreover, the existing chelating agents have strong selectivity to copper, and the selectivity to iron and other less harmful metals is better than that of lead. Under the condition of chemical metering control, they will preferentially react with copper, resulting in deviation of lead treatment effect.

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