Investigating the parameters governing the rate of leaching of primary sulfides copper deposits in in-mine recovery.

Abstract

It is expected that there will be very few viable approaches for mining mineral deposits in the future. This is because profit is constantly reduced as higher costs are associated with the required technologies and techniques to extract minerals from lower grades deposits in challenging geotechnical conditions. It is also expected to have additional constrains in terms of environment requirements in the mines of future. One of the mining techniques that might be useful for such conditions is In-Mine Recovery, IMR. Although very few studies have been done on this specific subject, it seems that IMR is environmentally friendly and can well fulfil the economic restrictions for several mining with challenging conditions. Additionally, by implementing IMR, the required mining developments can be significantly reduced. Material handling and comminution costs may also noticeably be decreased. There also would be much less pollution of the ground surface because of processing less materials on the surface. Therefore, main objective of this study is to investigate the effective parameters controlling the rate of leaching in IMR. For example, enhanced fragmentation can significantly improve the metal recovery of the leaching and improve the profitability of the mining method. Other relevant factors, such as mineralization, temperature, pH, aeration, leaching solution, time of leaching and height of the load of material, are also considered in this report to develop a robust and reliable numerical model(s) to estimate the recovery of the copper deposits for IMR. A case study of underground copper operation in Chile referred as “Mine A”, with a primary sulfide ore, a unique environment with unique geological and geo-mechanical conditions is considered in this research. The results show that the developed model is suitable and accurate enough for basic studies like, for the pre-feasibility study. It is noted that the prediction approach is highly dependent on various factors, such as shape factor of the fragmented rock particles as well as the mineralogical and geological characteristics of rocks. Performing detailed site inspections and evaluations are needed to properly calibrate the model and to estimate such factors. This can be achieved through performing small scale leaching tests as well as pilot and bed tests in sites. According to the sensitivity analyses that was done for the “Mine A” case, temperature is among the most influential factors affecting the leaching recovery. Pressure and Time are also the other important parameters that must be considered for implementation of IMR in primary sulfide ores.