A successful ore-sorting project assigned to technology solutions provider Tomra Sorting Mining has shown the potential benefit of including X-ray transmission (XRT) sensor-based ore sorting in processing procedures.

The ore sorting project, implemented in 2015, aims to improve productivity and extend the life-of-mine of Peruvian miner Minsur’s San Rafael tin mine, in Peru.

“The success of the project has demonstrated the high potential of Tomra’s XRT technology and, as a result, the miner plans to include XRT sensor-based ore sorting as a possible process route in all future projects,” the company says in a case study of the project.

The San Rafael mine contributed about 6% of the total world production of tin in 2015, when about one-million tons of ore, with an average grade of 2.13%, was mined and processed, resulting in 20 000 t of tin in concentrate.

The ore sorting project using Tomra’s XRT system resulted in several significant financial benefits, including notable reductions in the mine’s capital and operating costs, as well as payback on Minsur’s total capital expenditure in four months.

“By separating subeconomic material before entering the more cost-intensive wet processing, the project would address the bottleneck at the wet section and improve productivity by increasing the feed grade,” it explains.

The project was approved, fast-tracked and completed in 14 months, with a six-month ramp-up.

In 2017, it contributed about 36% – or 6 000 t – of Minsur’s total tin production.

Tomra’s XRT sensor-based ore sorting converts uneconomic waste material into economic ore, the company explains, noting that the material below the cutoff for the main plant can be treated at lower operating costs.

Another benefit is an increased capacity in the main plant, from 2 950 t/d before implementation to a current 3 200 t/d, as a result of the crushing operation at the XRT sorting plant.

The project also resulted in a significant improvement in the overall recovery in the main plant, from 90.5% to 92.5%.

An added benefit expected from the project would be the longer life of the mine, including an increase in reserves.

About 24% of the feed to the sensor-based ore sorting plant is low-grade ore from underground, which would have been excluded in the past for being below cutoff.

Further benefits include the elimination of liabilities through the treatment and proper disposal of 100% of the stockpile and decreased tailings disposal, as the sensor-based ore sorting system reduces the amount of waste by increasing the grade in the feed to the plant.