Four TOMRA sorting machines are improving the quality of a Turkish mining company’s quartz rock products, while also reducing operating costs. Guy Woodford reports
A highly respected producer of mined and processed quartz since 1991, Turkish company Mikroman Maden A.Ş (Mikroman) set itself the targets of improving product quality and increasing capacity at the firm’s three processing plants. Both goals are said to have been achieved, along with other gains, thanks to the installation of four TOMRA Sorting Mining (TOMRA) high-capacity, sensor-based sorting systems.
TOMRA designs and manufactures sensor-based sorting technologies for the global mineral processing and mining industries.
As the world market leader in sensor-based ore sorting, TOMRA is responsible for developing and engineering cutting-edge technology made to withstand harsh mining environments. TOMRA maintains its rigorous focus on quality and future-oriented thinking with technology tailor-made for mining.
As well as being the most efficient way to sort particles, sorting machines deliver a wide range of commercial advantages to industrial mineral-sorting businesses. These include a decrease in mining and haulage costs; reductions in energy and water consumption; improvements in quality and productivity; and increases in recovery. Sensor-based sorters also make it possible to significantly increase the lifetime of a mining operation.
In the case of Mikroman, quartz rocks are blasted and crushed at open-pit mines. The company runs its own mineral-processing plants for crushing, washing and sorting the raw materials. In 2018 the company installed a TOMRA PRO Secondary LASER sorting machine in two of its three plants, in Turkey’s Muğla and Aydin provinces. The third plant, in Usak province, invested in a LASER sorter plus a COLOR sorter.
TOMRA’s area sales manager, Jens-Michael Bergmann, explained: “TOMRA’s COLOR sorting machines employ a high-resolution camera that recognises materials based on their colour. Rocks with surficial and visible contamination are detected and sorted out, resulting in better recovery rates and higher quality than is possible with manual sorting.
“Our unique multi-channel LASER sorter delivers even greater benefits for Mikroman by achieving the highest quartz rock purity levels, while, at the same time, maximising profit. The scattering effect of multiple laser beams distinguishes a rock containing quartz from its identically coloured neighbour. Under the laser beam a pure or non-contaminated quartz rock registers as a glow crystal, whereas similar-looking rocks with no quartz content remain dark, without any visible scattering.”
Mikroman is said to have combined these two technologies for best results and recovery.
Of all three Mikroman processing plants, the one in Usak province required the most precise mineral sorting. Before sorting, the feed material is screened by size; the 40-100mm stones are treated as the highest priority; stones measuring 20-40mm are sent down the sorting line in a separate batch. Here, the combination of a TOMRA COLOR sorter and TOMRA LASER sorter is used to differentiate products according to four predetermined qualities.
White and light grey quartz, with low iron oxide content, for use as artificial stones (A); grey and yellow quartz, for use by the glass industry (B); coloured quartz, for ferrosilicon used by the metallurgical sector (C); and coloured gravel (D), also for ferrosilicon, currently goes with the waste.
After crushing and washing via a trommel screen, Mikroman’s sorting process consists of four key steps. In the first step minerals are screened by size, with only stones measuring 40-100mm going through to the next stage. In the second step, the LASER machine sorts out the waste and coloured gravel from the quartz pieces, processing up to 70 tonnes/hour of material. In the third stage, the remaining minerals are sorted into two streams: one for coloured quartz; the other for white and light grey quartz, and grey and yellow quartz. Finally, these two streams are hand-sorted into product types, with some further removal of remaining gravel and waste.
These precise distinctions, resulting in higher product quality, were not possible before the acquisition of the TOMRA machines.
TOMRA’s service team worked on-site with Mikroman, as it does with all customers, to optimise the performance of the machines.
Nazmi Çetin, mine and plant manager at Mikroman, said: “Before having TOMRA sorters, we were worried about quality and low capacity, but now we have achieved the desired quality standard and we have seen a decrease in waste, which means productivity has increased. The system design is quite successful and the TOMRA service team are good at their job.”
In addition to industrial mineral sorting, TOMRA’s technologies also effectively sort diamonds, all kinds of metals ores, slag metals and coal.
