Factors Affecting Solution Balance During in Situ Leaching of an Unsaturated Copper Ore Body.
SME Preprint 91-192 1991 :9 pages
An important operational and environmental concern associated with in situ leaching activity is the balance between solution injection and recovery. Solution balance is an important indicator of the capability of a particular in situ hydrologic design to efficiently and effectively control and distribute leach solution within the target ore zone. The U.S. Bureau of Mines is investigating the factors that affect solution balance in an unsaturated ore deposit as part of ongoing in situ leaching hydrologic investigations at the Cyprus Casa Grande Mine. Flow conditions in 58 injection and recovery wells at the Casa Grande in situ leaching test facility were monitored daily over an 18-month period. Changes in the balance between injection and recovery occurring during this period were evaluated using analytical and statistical methods. The results permit estimation of solution distribution and the volume of solution stored in microfractures and interstitial pore spaces within the deposit following 18 months of leaching. Approximately half of the difference between well injection and well recovery can be accounted for by solution movement through macrofractures into nearby drifts. Estimates of solution storage within the ore deposit at the end of 18 months of leaching range from 3.5 to 6.9 pct of injected solution. These results also suggest that 13 to 26 pct of the fracture-interstitial pore space in the deposit was saturated with solution after 18 months of leaching.
SME Preprint 91-192, 1991, 9 PP.