On the back of the excellent results achieved with the rental unit, Gem Diamonds purchased a Tomra COM XRT 2.0 sorter to replace the rental unit at the end of the contract. Featuring a bigger ejection chamber, higher belt speed and throughput, this unit was perfectly suited to the large diamond recovery set up the company was looking for, and they didnât have to wait for it to deliver:
âIn January 2018, we had pretty much just finished commissioning this unit and we recovered the biggest stone Letseng had ever seen, the 910-carat Lesotho Legend. There was no question about performance after that,â says Jaco Houman. âSince 2017, we have recovered 6 diamonds that were sold for more than 1 million US$ with the two Tomra XRT sorters.â
Since installing the Tomra COM XRT 2.0, the mineâs +5mm historic material has been depleted and the company is now focusing on scavenging and auditing the existent tailings. Jaco Houman explains: âAbout 10 tonnes a day of coarse fractions are stockpiled per export period, and we do roughly 8 exports a year. Over an average of about 45 days, we accumulate 450 to 500 tonnes, which we process at the end of the export period. We are seeking confirmation that all economical value has been recovered and  that nothing has been missed in our recovery process. By having this unit in place, we are now able to recover all the diamonds that are present in our concentrate, either through a first or a second pass.â
With its performance, the Tomra COM XRT 2.0 sorter has more than paid for itself, as Jaco Houman points out: âTo date, we have recovered about 15 times the investment value over the 4 years it has been in operation.â
Gem Diamonds purchases the first Tomra XRT Final Recovery sorter in the world
Gem Diamonds has been so impressed with Tomraâs XRT technology that they have become early adopters of its ground-breaking Final Recovery solution, purchasing a Tomra COM XRT 300 /FR sorter before it was even launched, so that the LetÅ¡eng mine is home to the first unit to be installed in the world.
Having found an effective solution for Coarse Recovery with the Tomra COM XRT 2.0 sorter, Gem Diamonds turned their attention to the Fines Recovery Circuit. âWe sent some samples for testing to an independent facility and our assumptions of under-recovery in certain size fractions were confirmed,â says Jaco Houman.
âWe wanted to find a solution to increase our revenue from the treatment of historic material. We were looking for a compact machine we could use as a final recovery sorter, and the Tomra COM XRT 300 /FR performs very well in that duty, or even as a single particle sorter. Also, it is a sorter that will treat a super-concentrate and work very well as a scavenging unit.â
âThe diamond industry had been waiting for 20 years for a way to introduce XRT directly into the Diamond Final Recovery instead of the bulk concentration stages where the DMS modules exist,â
explains Ryan Szabo, Sales and Project Manager Diamonds at Tomra Mining. âThe Tomra COM XRT 300 /FR is a compact sorter that can function within the diamond recovery and sort house environment, and it is the first to accurately sort diamonds based on their properties and not their proxies, achieving market leading recovery with the highest recovery factor to date. This made it ideal for Gem Diamondsâ requirements at the LetÅ¡eng mine.â
Tomraâs Final Recovery sorter is now in the commissioning stage, and performing well, as Jaco Houman states: âWe are getting consistent recovery from the Tomra COM XRT 300 /FR, which is performing to our expectations from this perspective. The overall throughput has not been attained due to deficiencies in the drying system upstream, which are making feeding the sorter at higher throughput rates difficult. However, design corrections are in the process of being implemented and I am confident that we will be able to demonstrate performance of the Final Recovery sorter at the higher capacities.â
âThe Final Recovery sorter has functioned exceptionally well,â adds Ryan Szabo. âTo date the sorter has never failed a performance test at the LetÅ¡eng Diamond Mine. It has already had successful results in the commissioning stage. In fact, itâs the most successful first implementation of a new solution that TOMRA has ever had.â
The installation of the Tomra COM XRT 300 /FR is the first in a series of three projects that Gem Diamonds is planning in order to upgrade its Recovery Plant with the addition of further Tomra XRT sorters. The company is also working on a project for the construction of a second recovery circuit that would combine the Tomra COM XRT 2.0 sorter currently on site, a new Tomra COM Tertiary sorter and a COM XRT 300 /FR sorter to create an off-line scavenging facility. This will be followed by a third project, which will look at implementing Tomra XRT technology through the remainder of the Final Recovery.
The last four years have seen the successful introduction of Tomraâs XRT technology at the LetÅ¡eng Diamond Mine, where it has provided effective solutions in different stages of the process, improving the operationâs profitability and efficiency. For Jaco Houman, this success stems not only from the advanced technology, but also from Tomraâs approach to serving its customers: âWhat I like about TOMRA, is that for them itâs not just about selling you a piece of equipment. If the equipment doesnât work in the solution or the system that you want, theyâd walk away from the sale. For me, this testifies to the fact that they have a vested interest in the success of your business.â
The support that Tomra has provided throughout the projects also stands out: âMy experience has only been positive. Weâre dealing with an organisation with experienced, professional people. I can see that they love what they do, theyâre very diligent in their work. The technical people on site have spent hours and hours not just setting up the equipment, but also imparting knowledge and getting the operational staff up to the required levels, so that when they walk away, we know that thereâs going to be continuity. I believe that when Tomra makes a commitment , you can bank on the fact that they will deliver on that.â