1986-12-08_GENERAL DOCUMENTS - M1977493 (2)

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t 2 The Federal Bureau of Mines has been conducting research on the utiliza- tion and stabilization of mineral wastes for many years (2, 4).3 The fine wastes represent the most difficult materials to stabilize. Many mining and milling companies have worked independently for many years and, during the past few years , cooperatively with the Bureau in evaluating various stabiliza- tion methods in the field. A free exchange of information has taken place. This paper reviews the various methods and presents cost estimates for stabi- lizing fine-sized milling wastes. Preliminary results of ongoing research by the Bureau of Mines for lowering maintenance costs and stabilizing special problem areas are reported. STABILIZATION PROCEDURES The principal methods for stabilization of milling was tes include the following: �f 1. Physical--the covering of the tailings with soil or other restraining materials. 2. Chemical--the use of a material to interact with fine-sized minerals to form a crust. i 3. Vegetative--the growth of plants in the tailings. i. The vegetative procedure is preferred in that esthetics of the area are improved while obtaining stabilization. Also, if a mineralized waste is to be j conserved for possible later retreatment or if the area is to be used later for residential construction or recreational purposes, it is beneficial to stabilize the area with vegetation. Vegetation does not hinder retreatment as much as covering the tailings with other foreign materials. Physical Stabilization Many materials have been tried for physical stabilization of fine tail- ings to prevent air pollution. Other than water for sprinkling, perhaps the most used material is rock and soil obtained from nearby areas. The use of soil often offers the advantage of effective cover while providing a habitat for local vegetation. Crushed or granulated smelter slag often has been used to stabilize a variety of fine wastes , notably inactive tailings ponds. On active tailings ponds, however, the slag-covered portions are subject to burial by shifting and newly deposited sands. Slag has the drawback, unlike �. soils or country rock, of not providing a favorable habitat for vegetation. y Other physical methods of stabilization evaluated include the use of bark " x covering, and the harrowing of straw into the top few inches of tailings to serve as a windbreak. Underlined numbers in parentheses refer to items in the list of references at the end of this report.