Model for ferric sulfate leaching of copper ores containing a variety of sulfide minerals: Part II. Process modeling of in situ operations

Abstract

The Lin-Sohn Leach simulation (DLS) computer model was used to simulate copper extraction from run-of-mine fragment size distributions expected for underground modifiedin situ solution mining. Ventilation was found to be a key variable in obtaining good copper recoveries, and the rate of ventilation was found to vary with ore type and through time. Improving recoveries and recovery rates with improved fragmentation was found to be more difficult than expected. Limitations on surface kinetics and bacterial ferric ion generation often erode benefits expected from reduction in diffusion limitation. Control of fines formation is difficult with the current state of the art in blasting. Fines may also improve the initial leaching rate at the expense of increased ventilation cost and more limited ultimate recovery. Ore grade was found to be less important to solution mining than to conventional copper recovery. Mineralogy was found to be crucial to solution mining economics. Mineralogy affects the grade of the ore and the importance of that grade. Pyrite was found to be helpful in increasing the ultimate copper recovery from ore but, at the same time, was found to reduce the rate of that recovery. Recovery rates were found to be very sensitive to mineral grain size, and calibration of DLS to a given ore may be especially important in this variable. Tortuosity and porosity of ore fragments appear relatively unimportant over the ranges typical of sulfide copper porphyry ore. Modifiedin situ solution mining appears to be a competitive option when a favorable ore type is available. The DLS computer code may be a valuable aid in screening options and selecting the most favorable orebodies.