Chemically Impregnated Sorbents for Mercury Control

During Phase I of this research project, ADA Technologies, Inc. (ADA) identified a new class of amended silicate sorbents, based on a novel amendment chemistry and amendment process. During Phase I, static bed testing identified sorbents with mercury capacities as high as 12,000 g per gram of sorbent. Testing of the new sorbents in a dynamic, in-flight test rig constructed during the Phase I project showed 85 percent mercury control at dosage rates of less than 7 lbs/MMacf. Testing of flue gas desulfurization powdered activated carbon under identical conditions consistently showed a significantly poorer performance. In Phase II, ADA will optimize the chemistry and preparation of the new sorbents to minimize costs compared to the current amended silicate sorbent formulation and will evaluate their performance in laboratory-scale test rigs under both static and dynamic conditions. Testing of the best formulations then will progress to a pilot-scale demonstration on a slipstream from an operating power plant to validate laboratory test data. The Phase II investigations will include testing the stability of the captured mercury in spent sorbents under three different leaching protocols. The sorbents, mixed with fly ash, also will be evaluated as concrete additives. In the Phase II Commercialization Option, ADA will prepare a 4,000 lb batch of sorbent to conduct a full-scale demonstration at a commercial power plant. It is anticipated that these amended silicates will provide a significant cost advantage over activated carbon, the current baseline technology, on the basis of cost, mercury capacity, and the ability to continue the use of fly ash as a concrete additive. The inability to use fly ash containing activated carbon as a concrete additive could double or triple the overall costs of mercury control for the utility industry. Furthermore, the need to replace fly ash currently used in concrete with Portland cement will add $750 million to the Nation's cost of dealing with mercury emissions, and also will lead to the release of an additional 12 million tons of carbon dioxide. ADA has formed a joint-venture company, Amended Silicates, LLC, to manufacture and sell these novel mercury control sorbents in commercial markets.