In October 2021, IMA Engineering participated in the 17th International Conference on Mineral Processing and Geometallurgy, Procemin-Geomet 2021 and presented a keynote on the Economics of pre-concentration in mining: Bulk Ore Sorting in a copper mine.

Pre-concentration by Bulk Ore Sorting (BOS) has gained interest in the mining industry over the past few years due to its environmental and economic benefits. The BOS method is utilizing reducing natural rock heterogeneity in separating the waste rock from the ore before it enters the energy-intensive grinding and mineral processing process.

The paper describes the BOS method and a test performed at a large copper mine.

The test was conducted by utilizing an online XRF analyzer and a belt scale on the mine’s main conveyor belt for measuring continuously the copper contents of the primary crushed ore in 30-second batches for Bulk Ore Sorting.

Ore and waste rock dilution tonnages and grades were measured. During the five-week test, 4.5 million tons of presumed ore was analyzed and 286 000 tons of below-cut-off waste rock was detected for BOS.  While the average grade of the ore was continuously above the cut of grade the used 30-second analysis time (the below blue line) revealed that a significant amount of ore was below the cut grade.