Variation of ore grades in the boundary zone of subeconomic ore

Deposits of non-ferrous, precious, and rare metals are predominantly complex-structured. Such bench blocks consist of economic and subeconomic ore. The boundary between the two types is defined by a cut-off ore grade. The numerical value of the ore grade in the subeconomic portion of a block determines the thickness of material that can potentially be admixed with shipped economic ore. Controlled admixing enables complete recovery of minerals from stopes while maintaining concentrate quality. For this purpose, exploration borehole data from five copper and gold deposits in Kazakhstan with complex structures were analyzed. Based on borehole data, trend equations were derived to describe ore grade variation in the subeconomic part of a block. A software tool was developed to automate the calculation of trend lines and their equations. Using this program, new dependencies were obtained for determining the ore grade in the shipped ore (α′). For the first time in mining science, a method has been substantiated for the complete recovery of economic ore from complex-structured bench blocks, based on admixing a controlled portion of subeconomic ore. This approach increases total ore extraction and improves valuable component recovery to concentrate. The potential increase in recovered components from shipped ore may reach 10–15% of total production.