Tag Archives: Stornoway Diamonds

TOMRA makes recovery promise to diamond miners

TOMRA is offering diamond mining customers a guaranteed diamond recovery of greater than 98% with the use of its sensor-based ore sorting technology.

The company is making this guarantee alongside a promise of 100% detection in the specified range, irrespective of luminescence profile or coating.

As the company says, maximising diamond recovery while optimising costs is the top priority for every diamond producer.

“With TOMRA’s holistic approach and cutting-edge technologies, both can be achieved to deliver outstanding results,” it said, adding that its X-ray Transmission (XRT) diamond recovery technology has helped recover some of the largest and rarest gemstones in history.

TOMRA says it approaches every project as a partnership with the customer to deliver a complete solution that meets their operational and business requirements.

This begins with a detailed analysis of the customer’s requirements and operational needs.

TOMRA – Operations Hub Johannesburg

Working collaboratively, it assists in developing a tailor-made flowsheet redesign that combines its XRT technology with its Near Infrared (NIR) and Laser solutions as needed. This collaborative approach continues throughout the project, with testing at its Test Center in Germany and, on-site, as required, through to installation and beyond.

More recently, this approach has been enhanced with the development of a remote testing option.

“The complete solution can also include the web-based TOMRA Insight platform that turns all the sorters into connected devices for monitoring and tracking the system’s performance,” the company said.

Once the system is fully operational, TOMRA offers its Service Level Agreement to ensure its solution continues to deliver the desired results.

“The tailored agreement can include on-site presence as required, seven days a week product support, application engineer visits, tiered urgency support, targeted site response, training, as well as spare and wear parts coverage to ensure maximum uptime and protect the customer’s investment,” the company said.

Advanced technologies adding value

TOMRA’s XRT technology recognises and separates material based on its specific atomic density. It uses a cutting-edge X-ray camera with DUOLINE® sensor technology to measure spectral absorption information.

TOMRA’s proprietary high-speed X-ray processing unit uses the data to produce a detailed “density image” of the material. The result is a high level of purity in sorting materials, irrespective of size, the degree of moisture or surface pollution present, TOMRA says. This makes TOMRA’s XRT high-capacity sorters effective in the recovery of free, liberated diamonds at high feed rates up to 300 t/h.

TOMRA’s NIR sorters recognise and separate kimberlite and waste rock based on their chemical composition. This technology is useful in upgrading lower grade run of mine and stockpiles, producing a kimberlite concentrate for further processing, the company says.

Marie-Claude Hallé had first-hand experience of how TOMRA’s solutions can add value to diamond mining operations when she held the role as Marketing Operations Manager for diamond exploration and producing company, Stornoway Diamonds.

“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,” Hallé said.

Customised solutions for kimberlite, lamproite and alluvial applications

With its customised approach, TOMRA says it can deliver on its promise of guaranteed results both in hard-rock kimberlite/lamproite and alluvial deposits – each of which presents their specific challenges.

In kimberlite, the challenge is to recover “needle in a haystack” diamonds, which requires controlled crushing of kimberlite ore to avoid damaging or breaking the diamonds, the company says.

“High waste dilution impacts the crushing energy needed and further increases diamond breakage risk,” TOMRA says. “Utilising TOMRA NIR technologies, we can remove non-diamond bearing material, not only improving the crushing profile of the ore, but also increasing the value of each tonne of ore processed. TOMRA NIR waste sorting technology can make diluted marginal kimberlite deposits economic.”

Additionally, complex, energy- and water-intensive kimberlite liberation processes, and the cost of transportation for crushing and processing, are challenges facing modern diamond miners today.

“TOMRA’s XRT and NIR technologies, which offer extremely high concentration factors, allow the production of hand sortable, ultra-high grade concentrates in as little as two stages compared to up to seven in traditional methods,” the company claims.

The challenge of economically mining low-grade alluvial deposits is due to their typically lower grade and the sporadic nature of the deposits.

The high recovery performance of TOMRA’s XRT technology enables single-stage or double-stage diamond recovery, offering a drastically lower operating cost and capital investment so that mining marginal deposits becomes economically viable, according to TOMRA.

“Another advantage of TOMRA’s XRT solution is that it can operate as a dry process, which dramatically reduces its environmental impact and operational complexity,” it says. “Besides, it opens the door to new opportunities, making it possible to mine deposits in arid areas where water access is minimal.”

TOMRA XRT machines have proved effective in alluvial operations, the company says.

One such case is that of the Lulo mine in Angola, operated by Lucapa Diamonds, where TOMRA XRT technology is used to process material between 18 and 55 mm in size and allows the recovery of diamonds of up to 1,100 ct – and where it has recovered Angola’s second-biggest diamond on record, a 227 ct stone in 2017.

Stephen Wetherall, Lucapa Diamonds Managing Director at the time of the recovery, said: “The recovery of the 227 ct diamond using the new XRT circuit justifies our investment in TOMRA’s large diamond recovery technology, which has more than paid for itself with the recovery of this one stone alone.”

Optimised flowsheet

TOMRA is in the unique position of being able to offer diamond operations a full XRT recovery flow sheet to 2 mm that delivers concentration factors up to 1 million with a much-reduced number of concentration stages, it says.

Geoffrey Madderson, Diamond Segment Manager for TOMRA Sorting Mining, explains: “TOMRA XRT technology replaces multiple stages of diamond concentration by virtue of its ability to concentrate diamonds to a hand sortable product after only a single step. This concentration factor allows for the removal of multiple recovery steps, drastically reducing both the capital investment and operational costs to recover diamonds.”

Geoffrey Madderson, Diamond Segment Manager for TOMRA Sorting Mining

TOMRA’s XRT technology can replace traditional methods such as dense media separation (DMS), wet magnetic separation and XRL final recovery with single-stage solutions for +8 mm and double-pass for -8 mm +4 mm particles, it claims.

“TOMRA’s solution eliminates up to seven concentration stages, dramatically reducing the complexity of the supporting plant and infrastructure,” the company says. “This results in significantly lower power and water consumption, which not only reduces costs, but also the environmental impact of the recovery process.”

An additional benefit of TOMRA’s solution is that it is a fully automated process, so there is no manual handling during pre-concentration and recovery, which has positive implications on security and eliminates human error, resulting in greater accuracy, the company says.

Recoveries

TOMRA’s sorters process these volumes with great efficiency, finding more diamonds than other, traditional separation methods – including coated and low- or non-luminescent diamonds, the company says.

The performance of its XRT sorters is independent of the “heavies” content in the feed, and is ideal for processing high-yielding ores unsuitable for DMS. The result is an exceptionally high recovery rate, it claims.

“TOMRA guarantees >98% recovery: that is how confident we are in our technology,” Madderson states.

With TOMRA’s sorting solutions, diamond producers can install large diamond recovery systems with a small capital investment and operate with a fraction of operating expenditures per tonne compared with traditional recovery methods such as DMS and XRL, it claims. In addition, the economic recovery of ultra low-frequency exceptional diamonds of +32 mm is now possible.

“TOMRA’s ability to deliver not only a technology that can detect such large diamonds, but also an economical process solution for the recovery of ultra-rare, exceptional diamonds is what sets it apart from its competitors,” Madderson said.

“This is the reason that, to date, TOMRA XRT has become synonymous with the recovery of extraordinary diamonds from all around the world.”

TOMRA delivers the goods at Stornoway Diamonds’ Renard mine

TOMRA’s ore sorting technology has delivered impressive results in its first diamond processing plant application. 

The company worked with Stornoway Diamonds and its Renard diamond mine, in Quebec, Canada.

The Renard mine, in commercial production since 2017, is the first diamond mine in the province and one of six in Canada. It 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, according to TOMRA.

“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 orebody 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 to 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 needed to find a way to reduce its costs and optimise its operation, which is where TOMRA came in.

“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,” Marie-Claude Hallé said.

TOMRA’s solution incorporates ore sorting technology into the mine’s processing plant.

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 the traditional Dense Media Separation method could not provide an efficient and cost-effective solution. It led to TOMRA making Renard the first diamond mine to incorporate ore sorting into its processing plant.

TOMRA addressed the mine’s recovery issue with its leading 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.

TOMRA’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, TOMRA said.

TOMRA also included 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.

Hallé continued: “The TOMRA solution we have in operation has offered us a very low-cost, efficient reliable means of recovering our coarse diamonds without inefficiency, without causing diamond breakage.

“It’s a very neat way to get those diamonds out of the kimberlite at the very early stage of the process. We reduce our power consumption cost, we reduce our wear and tear on material.

“We are still optimising this unit, and we feel there are even more benefits to come in terms of how it helps enhancing the overall recovery of our diamonds.”

Geoffrey Madderson, Diamond Segment Manager at TOMRA, concludes: “The implementation of this plant proves that TOMRA waste sorting technology can successfully be used to upgrade lower grade run of mine and that sensor-based sorting can be used to further improve value recovery for our clients on lower-grade resources.”

TOMRA said the integration of the ore sorting plant into the main processing plant was completed smoothly, with its full involvement in the ore sorting plant design. TOMRA also had a team onsite for the first three months of operation to ensure a seamless transition, and will continue to provide ongoing support for the entire life of the equipment.

“We chose TOMRA because we find TOMRA’s approach to problem solving to be very innovative,” adds Hallé. “We see them as a solution provider that thinks outside the box, that doesn’t always come with ‘here’s the off-the-shelf solution to your problem’, but in fact engages with us and looks at what are the best possible options.

”In fact, it will develop technology if needed to address those specific problems. We always have outstanding service as well, from TOMRA technicians, from engineers, from every aspect of TOMRA Sorting.”

TOMRA XRT ore sorter starts to pay off at Stornoway’s Renard diamond op

The June quarter at Stornoway Diamonds’ Renard diamond operation in Quebec, Canada, started to show the positive results of using ore sorting technology.

Commissioning of the TOMRA X -Ray transmission plant commenced in March and was completed during the most recent quarter.

Among a quarter that saw lower quarter-on-quarter carat production (223,351 carats) and diamond grade (40 carats per hundred tonne) – previously expected with the transition from openpit to underground mining – the initial performance of the ore sorting plant stood out.

Stornoway said: “The new ore sorting plant at Renard … has been processing ore on a consistent basis since mid-May. The volume and quality of waste segregated from the ore feed has exceeded expectations, with waste rejected representing between 15% and 30% of material sorted.”

The company noted that kimberlite content in the waste stream had averaged between 1% and 2%.

And, the TOMRA ore sorter has even reduced Renard’s power requirements, according to Stornoway.

“Because the waste within the Renard ore is hard and difficult to crush, its rejection from the main process plant has also resulted in a net reduction in power consumption for processing even with the addition of the new sorting circuit,” Stornoway said.

“Considering the highly abrasive characteristics of the ore processed to date through the plant, consisting mainly of highly diluted, low grade material, the diamonds recovered since its introduction have exhibited lower levels of breakage than observed previously with comparable feed composition.”

Stornoway CEO Matt Manson said these initial diamond results were encouraging and, given the volume and quality of the waste being rejected, the company saw potential for upping processing capacity in its plant beyond the current nameplate rating.

As a result, Stornoway is now thinking about developing a modified mine plan to support the accelerated mining required.

Just last week, a TOMRA XRT ore sorter was commissioned at the Renison tin mine in Australia, with the operators expecting a 15-20% increase in tin production with its introduction.