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Ore sorting technology delivers improvement to Stornoway Diamonds’ Renard mine

Published by , Editorial Assistant
Global Mining Review,

Stornoway Diamonds owns and operates the Renard Mine, which has been in commercial production operation since 2017. It is the first diamond mine in Québec and one of six in Canada. Renard started with an open pit mine and subsequently opened an underground mine.

The conditions of the mine presented Stornoway Diamonds with particular challenges that required an innovative approach: “Due to the geology of our ore, meaning we produce very high yield, we have lots of material that we need to sort through. At times, we have the possibility of losing some of those very expensive diamonds due to inefficiencies,” explains Marie-Claude Hallé, Marketing Operations Manager for Stornoway Diamonds. In addition, “our ore body at the Renard mine contains a high level of internal and external dilution called country rock, a significant issue for us, as it can make up to 30 - 40% of the feed to the plant. With that comes very, very high energy cost from crushing all this waste material that is not diamond bearing. It causes a tremendous amount of wear and tear on our equipment from screening conveyors, diamond recovery equipment, and on a dollar-per-tonne basis we spend a lot of money processing non-diamond bearing material.”

Stornoway Diamonds needed to find a way to reduce its costs and optimise its operation, and they are fully satisfied with the solution provided by the company: “You have to really envision that TOMRA has actually changed the game in terms rough diamond recovered around the world, and allowed producers to access large exceptional quality goods that perhaps in the past would be crushed to pieces,” states Marie-Claude Hallé.

TOMRA analysed the situation and worked closely with Stornoway Diamond’s team to design and install a Kimberlite pre-concentration plant. The specific conditions at the Renard mine meant that the traditional Dense Media Separation method could not provide an efficient and cost-effective solution. It required innovative approach, which TOMRA delivered, making Renard the first diamond mine to incorporate ore sorting into its processing plant.

The company addressed the mine’s recovery issue with its sorting technologies, developing a solution with four key objectives for the ore sorting plant: minimise diamond breakage by removing hard rocks from the crushing plant feed, upgrade the quality of the material to the process plant by increasing the proportion of Kimberlite to waste rock, reduce the energy required for crushing by removing the harder rocks, and improve circuit efficiencies throughout the plant.

The company’s solution features five PRO Near Infrared (NIR) sorters in its ore sorting circuit. This technology is particularly well suited to enable discrimination between the various ore and waste materials that need separation at the Renard mine, based on their different chemical composition.

It also included in a COM XRT 2400 sorter, which uses X-Ray Transmission technology to separate material according to its specific atomic density, in the plant’s large diamond recovery circuit.

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