Arsenic is the twentieth most abundant elements in the earth's crust and is known to appear in 245 mineral species. It is found in appreciable concentrations in association with sulfide deposits with arsenopyrite (FeAsS) the most common form. Becayse if its relative abundance and modes of occurrence, it is a contaminant of coals, iron, ore phosphate rock and nonferrous metals. Domestically, arsenic is produced as arsenic trioxide recovered as a by-product from copper smelting and is used to produce arsenic metal and some 45 other compounds of commecial significance.

Caption title. At head of title: Project summary. "Sept. 1981." "EPA/600-S2-81-049."

"Arsenic is the twentieth most abundant element in the earth's crust and is known to appear in 245 mineral species. It is found in appreciable concentrations in association with sulfide deposits with arsenopyrite (FeAsS) the most common form. Because of its relative abundance and modes of occurrence, it is a contaminant of coals, iron ore, phosphate rock, and nonferrous metals. Domestically, arsenic is produced as arsenic trioxide recovered as a by-product from copper smelting and is used to produce arsenic metal and some 45 other compounds of commercial significance. Uses include pesticides, animal hide and wood preservatives, feed additives, metal alloys, glass and pigment manufacture, solar cells, and catalysts. Most compounds of arsenic are extremely toxic and the element is also a suspected carcinogen. Because of the potential hazards associated with arsenic disposal, the Industrial Environmental Research Laboratory at Cincinnati, Ohio, sponsored a research project at the Mineral Research Center, Montana Tech Alumni Foundation, to investigate a variety of approaches to the fixation of arsenic-bearing wastes, particularly smelter flue dusts, to render them harmless to the environment. The program was comprised of three principal elements: (1) separation of the arsenic from metal values by leaching; (2) incorporation of the arsenic into a fixation matrix; and (3) leach testing of samples of the fixed product to determine suitability for environmental protection. Stabilization of the arsenic by incorporation in slag matrices and in cements, mortars, clays and concrete was investigated. The most promising technique found was stabilization by dissolution in a slag matrix to form a solid solution upon cooling. The slag fixation products yielded leachate concentrations of from 0.02 to 4.5 ppm for arsenics in slag loadings ranging from 7 to 24 percent arsenic."