Immobilization of Heavy Metals by Solidification/Stabilization in Challenging Coal Fly Ash and in Co-Disposed Coal Fly Ash and Concentrated Brines

Start Date:
Mar 2013

Award Amount:
$160,000

More stringent regulations to control heavy metals in flue gas emissions are expected to lead to new solid and liquid waste with higher heavy metal concentrations at coal-fired power plants. This project will develop solidification/stabilization (S/S) technology with Portland cement for the disposal of new baghouse coal fly ash and the co-disposal of fly ash and concentrated brines from the power industry. The relevance of this project to the Environmental Research & Education Foundation’s strategic research plan is as follows:

• Develop effective S/S technology for waste pre-treatment of new baghouse fly ash and of concentrated flue-gas-desulfurization (FGD) brines for landfill disposal.
• Improve the effectiveness of S/S processes using coal fly ashand Portland cement for challenging fly ashes and waste brines of high metal and salt concentrations.
• Improve the mechanistic understanding of heavy metal immobilization in S/S processes using fly ash and Portland cement.

It will greatly benefit the solid waste industry to gain understanding of the best practices to immobilize metals in these new forms of waste (new baghouse fly ash and concentrated brines) from the coal fired-power industry. The primary research objectives of the project are:

• Determine the physicochemical characteristics of new baghouse fly ash;
• Evaluate the immobilization of heavy metals in new baghouse fly ash by Portland cement;
• Evaluate the immobilization of heavy metals and chloride in co-disposed fly ash and concentrated FGD brines;
• Evaluate the impact of coal fly ash properties and brine chemistry on the S/S process and metal immobilization; and
• Evaluate the predominant minerals formed in the S/S process and their stability.