Permeability Properties of Fly Ash from Furnace Sorbent Injection Process

摘要

The paper discusses tests of the applicability of furnace sorbent injection (FSI)waste solids for use as synthetic waste landfill liners by measuring the mechanical strength and permeability of moisture-cured samples. FSI waste solids were received from the EPA-sponsored demonstration of limestone injection multistage burner (LIMB) technology at Ohio Edison's Edgewater power plant. The demonstration coal was about 3% sulfur, and the sorbent used was calcium hydroxide--Ca(OH)2--modified with lignosulfonate. Samples of FSI waste were moisture-cured and analyzed for formation of ettringite, which--in cementitious systems--can cause disruption of structure if formed after the cement paste has hardened. No ettringite was detected and mechanical strength, as measured by unconfined compressive strength, increased with longer moisture curing time. Permeability of moisture-cured samples decreased with increasing moisture curing time. The increase of mechanical strength and accompanying decrease of permeability are believed to be due to the effect of the formation of bonds between the fly ash and Ca(OH)2 with subsequent filling of intraparticle voids, evidenced by increasing specific surface area of FSI waste samples cured for long periods of time. Examination of morphology by SEM confirmed structure development.