Abstract: A calcium-alumino-silicate composition comprising the reaction product of electric arc furnace dust and/or an aqueous chemical waste sludge including a source of ferrous ions and selective additive materials, the additive materials are selected so that the total composition of the additive ingredients and said sludge includes fly ash, electric arc furnace dust, lime kiln dust, ferrous sulfate, hydrated lime to provide an alkalinity of about 9 to 9.5% and water, the composition contains at least 0.2% by weight of ferrous ions and is hardenable through chemical reactions, the product of which includes calcium-alumino-silicates.

Abstract: This invention is directed to a process for the chemical stabilization of heavy metal bearing dusts and sludges. A preferred use for such process is the treatment of dust from an electric arc furnace (EAF). In the production of steel by the electric arc furnace process, a by-product thereof is the generation of EAF dust. Such dust, by virtue of the presence of such elements as cadmium, hexavalent chromium and lead, is classified as hazardous waste by U.S. Environmental Protection Agency (EPA). The present invention is directed to a process for the chemical stabilization of the inorganic EAF dust to render the hazardous constituents thereof virtually immobile. Such process is based on the pozzolanic reaction of materials containing anhydrous alumino-silicates which, in the presence of lime, water and chemicals, adsorb and/or physically entrap the heavy metals present in EAF dust into a calcium-alumino-silicate matrix.

Abstract: The concentration of a selected gas specie at a situs determined by directing a laser beam at the situs, the beam including a wavelength within the resonance absorption band of the gas specie, and measuring the intensity of the laser beam energy scattered from two spaced volumes along said beam at the situs. The ratio of measured intensities is a relative measure of the concentration of the gas specie at the situs.