Ore leaching in underground stopes.
Boreck-DL; Lutzens-WW; Speirer-RA
Paper in Proc 1989; :143-153
Research is currently being conducted by the U.S. Bureau of Mines on determining the feasibility of incorporating in situ stope leaching into active underground metal and nonmetal mines. This modified in situ technique proposes to recover metals from ore by creating underground rubblized stopes, leaching the stopes underground for metal recovery and collecting and processing the metal-bearing solution. Stope leaching incorporates stope design and fragmentation techniques for developing optimum sized rock particles, chemical lixiviants for metal extraction from the broken rock, and solution control techniques to prevent loss of metal- bearing solution. Increased temperatures and pressures can theoretically be applied for metal recovery enhancement. Stope preparation requires removing as much as 25 pct of the ore to create a void space for subsequent swell during the fragmentation process. Fragmentation can be achieved either by blasting or by allowing the ore to cave naturally. If high-grade ore has already been removed, broken low-grade ore, extracted from elsewhere in the mine, may also be dumped into the stope. Management of the leach solution is an important part of stope design. Escaping solutions result in loss of the target metal and possible contamination of the ground water. Solution management can be broken down into three major elements: (1) detection of solution loss, (2) solution control during active leaching, and (3) stope closure.
Paper in Proc. 1989 Multinational Conf. on Mine Planning & Design, Univ. Kentucky, 1989