There’s more to preconcentration, or progressive waste rejection, than meets the eye
It’s no secret that ore grades across key commodities are declining. For decades, mines have sought to counteract lower grades by extracting and processing greater volumes of material and, for many years, this approach worked well.
The Power of Bulk Sorting
Although there are many technologies that can be used to reject waste throughout the mining process, when it comes to true preconcentration, sensor-based ore sorting is one of the most effective, and also quickest and easiest methods to implement.
While particle sorting identifies and rejects individual rock particles, usually on a conveyor belt, based on their mineralogical composition (very useful in diamond operations, for instance), bulk sorting analyzes larger samples of material and accepts or rejects them based on a predetermined cut-off grade. This makes it suitable for use with less selective mining methods and lower grade orebodies. Bulk ore sorting is typically performed on a conveyor belt or directly at the mine face via technology mounted on shovel buckets.
“At MineSense, we feel preconcentration is best conducted at the face where the maximum benefit to the mine can be achieved,” said Claudio Toro, executive vice president for business development at MineSense. “If mines can perform ore sorting at the earliest and most effective point — at extraction — this mitigates the needless transportation and processing of waste rock, which is extremely costly and wasteful (estimated at over 60% of the cost of production).”
MineSense’s ShovelSense technology performs ore sorting using X-ray fluorescence (XRF) sensors to analyze and grade the material mined in each excavator bucket load. Preconcentration is achieved via automated truck diversion, sending only high-grade truck loads to processing and uneconomical loads to waste. This saves a huge amount of chemical reagent use, as well as water, energy and time.
“Mines today face two critical challenges,” Toro explained. “Firstly, increased demand for metals needed to realize a low-carbon future. Secondly, mines must lower their impact on the environment. ShovelSense is a complete hardware and software system that addresses these challenges. By identifying and extracting more payable metals as the machines excavate material, it maximizes the potential of the orebody. The variability of the raw material — ore or waste heterogeneity — is capitalized on at the earliest possible moment where the impacts on profitability and sustainability are greatest.”
Toro added that MineSense has seen significant growth in interest surrounding ShovelSense in recent years as ore grades decline and deposits become more complex. ShovelSense is particularly effective in orebodies that have a high level of heterogeneity so can play a role in helping to bring previously uneconomic projects to bear.