Study on the Characteristics of Heavy Metal Lead in Desulfurization Sludge Solidified by Coal-Fired Fly Ash in Power Plant

Abstract

ObjectivesThe enrichment of heavy metals in desulphurization sludge of coal-fired power plant is significant, so it is necessary to reduce the content of heavy metals in desulfurization sludge.MethodsThis paper put forward the idea of solidifying heavy metals in desulfurization sludge with fly ash from power plants and compared with common curing agents.ResultsAmong cement, fly ash, chelating agent DTC (dithiocarbamate) and chelating agent TMT-15 (trisodium thiocyanate), fly ash has the best solidification effect on lead in desulfurization sludge. The solidification efficiency of different fly ash and desulfurization sludge is between 40% and 100%. The mechanism analysis shows that, similar to cement, the chemical composition of fly ash mainly contains SiO2, Al2O3, CaO and Fe2O3, etc., which can react with desulfurization sludge to generate hydration products such as hydrated calcium silicate C-S-H and ettringite, etc. It is beneficial to the solidification of heavy metals. The products can adsorb heavy metals such as lead.ConclusionsIt can be seen that adding a certain proportion of fly ash into the desulfurization sludge of coal-fired power plants can realize the solidification and stability of lead, which provides a method for reducing the desulfurization sludge from dangerous solid waste to general solid waste.

Keywords

• coal-fired power plants
• desulfurized sludge
• fly ash
• stable solidification