Mercury removal from MSW incineration flue gas by mineral-based sorbents

Abstract

Three samples of commercially available mineral-based sorbents (zeolite, bentonite and diatomaceous earth) were selected and evaluated for Hg capture under conditions of simulated dry flue gas atmosphere typical in Municipal Solid Waste Incineration (MSWI). The experiments were carried out in a lab-scale fixed-bed device at temperatures between 120 and 200 °C. Two samples of activated carbons (AC) (raw-AC and sulphur impregnated AC) were tested under the same conditions. The mineral-based sorbents were chemically promoted by sulphur, FeCl and CaBr, achieving an improvement in the overall reduction percentage of Hgout (g) up to 85%, which was comparable to that obtained using a commercial activated carbon for Hg capture (sulphur impregnated AC). The study demonstrates that sorbents with a matrix relatively richer in TiO, FeO and AlO, as bentonite, favour Hg heterogeneous oxidation. The best Hg capture capacity was achieved with a zeolite sorbent sample characterized by high specific surface (132 m/g) and impregnated with elemental sulphur. The final form of mercury retained in this sorbent was HgS with proved long-term stability in disposal and landfilling. The higher the temperature, the lower the efficiency of Hg capture being the optimum temperature for Hg-capture in the range of 120-150 °C. This study provides a basis for the development of new efficient non-carbon sorbents for mercury removal in the air pollution control lines of MSWI facilities considering the non-hazardous final form of mercury and its long-term landfilling/sequestration.

Experimental Investigation of the Reactivity of Sodium Bicarbonate toward Hydrogen Chloride and Sulfur Dioxide at Low Temperatures

“…Both activated carbon and novel alternative mineral-based adsorbent materials ensure acceptable Hg removal efficiencies at temperatures lower than 190 °C. 40,41 This constraint does not penalize the NaHCO 3 -based abatement of acid gases: as already discussed, on the basis of the present results, if both HCl and SO 2 are present in the gas stream, the optimal operating temperature would be in the range between 150 and 180 °C.…”

“…In most cases, a further constraint to the operating temperature of DSI systems is given by mercury (Hg) removal, which is typically performed by means of activated carbon, injected in DSI together with the acid gas sorbent. Both activated carbon and novel alternative mineral-based adsorbent materials ensure acceptable Hg removal efficiencies at temperatures lower than 190 °C. , This constraint does not penalize the NaHCO 3 -based abatement of acid gases: as already discussed, on the basis of the present results, if both HCl and SO 2 are present in the gas stream, the optimal operating temperature would be in the range between 150 and 180 °C.…”

Mercury Removal from Flue Gas by Noncarbon Sorbents

“…Clay minerals, including montmorillonite, kaolinite, bentonite, vermiculite, and attapulgite, are a class of layered alum silicates. − The application potential of clay minerals in removal of Hg 0 is well documented, ,− attributed to their low-cost and strong expansibility. The raw clay minerals have been found to be inefficient for Hg 0 removal, , since physisorption was dominant for Hg 0 removal over unmodified clays.…”

“…Clay minerals, including montmorillonite, kaolinite, bentonite, vermiculite, and attapulgite, are a class of layered alum silicates. − The application potential of clay minerals in removal of Hg 0 is well documented, ,− attributed to their low-cost and strong expansibility. The raw clay minerals have been found to be inefficient for Hg 0 removal, , since physisorption was dominant for Hg 0 removal over unmodified clays. However, the small particle size and high surface area of natural clay minerals facilitate physical and chemical modification, hence improving their adsorption capacities of Hg 0 .…”

A Novel Furfural Residue Activated Carbon Powder for the Removal of Flue Gas Hg0

“…After a series of combustion processes within a boiler, domestic waste generates not only fly ash but also significant quantities of flue gas containing pollutants, such as nitrogen oxides (NO x ), sulfur oxides (SO 2 ), and mercury (Hg). 1 Mercury has been shown that it could enter the human body through breathing, skin absorption, and food intake, causing serious damage to the central nervous system. Therefore, Hg pollution is gradually becoming a major concern.…”