STABILIZATION OF AT LEAST ONE HEAVY METAL CONTAINED IN A SODIC FLY ASH USING A WATER-SOLUBLE SOURCE OF SILICATE AND A MATERIAL CONTAINING CALCIUM AND/OR MAGNESIUM

摘要

A treatment method for stabilizing at least a portion of at least one heavy metal contained in a sodic fly ash to reduce leachability, wherein the sodic fly ash is provided by a process whereby a sodium-based sorbent is injected in a combustion flue gas to remove pollutants therefrom. The treatment method comprises contacting the sodic fly ash with at least one water-soluble source of silicate and at least one additive comprising calcium and/or magnesium. The material obtained from the contacting step is preferably dried. The additive may be selected from the group consisting of lime kiln dust, fine limestone, quicklime, hydrated lime, dolomitic lime, dolomite, selectively calcined dolomite, hydrated dolomite, magnesium hydroxide, magnesium carbonate, magnesium oxide, and any mixture thereof. A particularly preferred additive comprises lime kiln dust and/or dolomitic lime. The heavy metal to be stabilized in the sodic fly ash may comprise selenium and/or arsenic.

主权项

1. A treatment method for stabilizing at least one heavy metal contained in a sodic fly ash, wherein the sodic fly ash is provided by a combustion process in which a sodium-containing sorbent is injected into a flue gas generated during combustion to remove at least a portion of pollutants contained in the flue gas,said treatment method comprising:
(A) contacting said sodic fly ash with at least one water-soluble source of silicate and at least one additive comprising calcium and/or magnesium to form a material which has a reduced leachability of at least one heavy metal compared to the sodic fly ash before contacting, wherein said at least one water-soluble source of silicate comprises sodium silicate, potassium silicate, or combination thereof; and (b) drying the material obtained in step (A) at a temperature equal to or more than 100° C. and/or at a temperature equal to or less than 150° C.