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Maximising the benefits of sensor-based ore sorting machines

Base metals, Comminution of minerals, Environmental, Mine operation news, Mineral processing, Mineral project development, Mining services, Power supply for mines, Precious metals, Sustainable mining, Water management, , , , , , , , , , , , , , , , , , , , , , , ,

Ore sorting has been shown to provide both economic and environmental benefits, but many mines are not yet fully utilising this technology, according to HPY Technology.

Yet, the company’s ore sorting machines are providing a breakthrough solution for Fankou, one of Asia’s largest lead and zinc mines, resulting in an annual revenue increase of around $9.22 million.

Located in Renhua County, Shaoguan City, Guangdong Province, Fankou is owned by Shenzhen Zhongjin Lingnan Nonfemet Co Ltd. The mine has been producing lead and zinc for over 60 years. However, with new underground mining processes, such as vertical crater retreat and large blasting, more waste rock is being introduced into the crushing, grinding and flotation processes, resulting in higher production costs and energy consumption.

Furthermore, under the “zero waste” target set by the Environmental Protection Law of China, Fankou’s tailings pond needs to be closed by 2025. As of 2018, the mine’s annual processing capacity was 1.5 Mt, with 600,000 t ending up in the tailings pond. In addition, Fankou’s waste rock piles had reached approximately 2 Mt. With the continuous addition of around 200,000 t/y of waste rock, these piles grew larger. With the pressure to meet the zero waste target, Fankou was under pressure to make a change.

In 2017, Fankou conducted exploratory tests of sensor-based ore sorting machines with Ganzhou HPY Technology Co Ltd. The result of the initial tests showed promise and addressed the problems the mine was beginning to face, according to HPY Technology. As a result, Fankou decided to add HPY Technology’s ore sorting machines to the industrial design plan of their mineral processing plant in 2018, and HPY Technology’s machines were officially added to the plant in 2019.

The Fankou lead-zinc mine currently produces about 1.4 Mt/y of ore, and it is expected that more than 105,000 t of waste rock will be pre-rejected from the raw ore throughout the year. Ore sorting technology can discard a large amount of waste rock from the raw ore before it is fed into the flotation system, reducing the amount of waste rock entering the mill and saving on electricity costs.

Fankou’s mineral processing plant uses four Classic Series P60-X1400 ore sorting machines. The machine processes the particle size range of +12-90 mm, which accounts for about 50% of the raw ore. This accounts for 2,600 t of ore, rejecting 400-500 t/d of waste rock. After pre-concentration, the lead and zinc content in the waste rock are below 0.3%, and the sulphur and iron content is below 3.8%. Therefore, the ore sorting process enriches the ore grade by 1.08% for lead and zinc and 2% for sulphur and iron.

Four Classic Series P60-X1400 ore sorters in Fankou’s mineral processing plant

After sorting the waste rock from the raw ore, this waste rock can be sold as construction aggregate to bring further economic benefits to the Fankou mine. This has also seen the amount of tailings decrease and the service life of the tailings pond extend significantly, resulting in remarkable energy savings and consumption performance, while also enhancing the mine’s societal value, HPY Technology says.

Mr Wang, Project Manager of Fankou Mineral Processing Plant, said: “We are proud to be one of the world’s first lead and zinc mines to utilise ore sorting fully. We see significant economic benefits for using HPY Technology’s ore sorting machine, especially for low-grade mines. China has huge lead and zinc ore reserves, the second largest in the world. But the grade of the deposits is generally low, with many poor and few rich ores. The average grade is about 1.5% for lead and 2.5% for zinc. Reserves with a grade below 5% account for more than 90% of lead ore, and reserves below 8% account for more than 85% of zinc ore. We hope to continue contributing to the mining industry’s progress and are willing to recommend HPY Technology’s ore sorting machine to our peers.”

The Classic Series used in Fankou’s mineral processing plant is a benchmark in the ore sorting industry, according to HPY Technology. This machine uses dual-energy X-ray technology, combined with high-speed air jets to sort ore from waste rock. The X-ray technology penetrates the ore and creates a grayscale image that distinguishes between target and vein minerals. This image is then processed by an artificial intelligence algorithm, which uses the information to accurately sort the ore and waste rock. The Classic Series has undergone numerous iterations, ensuring stable and efficient operation, HPY Technology says. It is currently the most widely used ore sorting machine in China’s mining industry, according to the company.

Fankou Lead-Zinc mine, mineral processing plant

HPY Technology | Fankou lead-zinc mine, mineral processing plant
Machine used Four Classic Series P60-X1400
Processing capacity 2,600 t/d
Particle size +12-90 mm
Concentrated ore grade (Pb+Zn) 12%
Waste rock grade (Pb+Zn) <0.3%
Grinding grade (Pb+Zn) increased by 1.08%
Rejection rate 16-17%

Fankou’s mineral processing plant can save more than $2.9 million/y by using HPY Technology’s ore sorting machines, resulting in an annual profit margin of more than $7.8 million, considering the comprehensive benefits of increased plant capacity, tailings reduction and construction aggregate sales.

In addition to the four Classic Series P60-X1400 in the mineral processing plant, the Construction Materials Plant has three HPY Technology ore sorting machines to process the waste rock from the mineral processing plant and its existing waste rock piles. The waste rock is taken to the construction material plant for another round of sorting, with the remaining waste rock being used for construction aggregates. The three machines at the construction materials plant also process the 2 million cu.m of waste rock initially stockpiled in the tailings pond.

Mr Luo, Project Manager of Solid Waste Treatment, said: “In the past, we could only transport solid waste back to the shaft for filling. After using HPY’s ore sorting machines, we can now sort out all the ore from solid waste and recover the value of the resources. The remaining waste rock can be sold as construction aggregates, which is a win-win solution. Currently, we are also sorting waste rock that was stored before using HPY’s ore sorting machines. The ore grade is about 3%. Sensor-based sorting technology enriches the ore grade to 12-14%. Sorting results show that the rejection rate exceeds 95%. In the global mining industry, Fankou is one the first to successfully apply intelligent ore sorting technology in lead and zinc mines, achieving maximum resource value recovery and is great for the environment.”

According to Mr Luo, waste rock that was initially made into construction aggregates now yields more than 1,500 t/y of lead and zinc metal, which has been able to be recovered through the Construction Materials Plant. In addition, the ore sorting process reduces the waste rock’s sulphur content. This substantially improves the grade of the construction aggregates, increasing its sales price. As a result, the waste rock made into construction aggregates generates about $977,000/y in economic benefits. In addition, the recovered ore generates over $2.8 million/y in benefits.

Fankou has utilised sensor-based ore sorting to its full extent, HPY Technology says, using it during the comminution process to pre-reject waste rock to increase its lead-zinc ore grade. The company also sees benefits from pre-rejected waste rock in reduced costs in its grinding process. With pressure to control the amount of tailings, the pre-rejected waste rock lowers the amount of tailings entering the tailings pond to help the company in its aim of closing the tailings pond in 2025. In addition, sensor-based ore sorting has allowed the company to gain additional revenue through the recovery of lead-zinc from their waste rock piles, while also utilising these piles for construction aggregates. Overall, the introduction of ore sorting has allowed the company to expand its resource recovery. By pre-rejecting and enriching low ore grades, Fankou can now mine areas previously deemed un-mineable due to having low grade ore, allowing them to increase the processing capacity each year.

Fankou lead-zinc mine, Construction Materials Plant

HPY Technology | Fankou lead-zinc mine, Construction Materials Plant
Machine used One Insight Series | Two Classic Series
Concentrated ore grade 12-14%
Waste rock grade Pb 0.04%, Zn 0.10%
Concentrate recovery rate Pb 96.76%, Zn 92.8%
Rejection rate 95%
Enrichment ratio Pb 9.68, Zn 9.28
Particle size +10-50 mm

The Insight Series used in Fankou’s Construction Materials Plant adopts a combined detection method comprised of a VIS HD dual-sided imaging system and X-ray technology, which can be customised according to the physical characteristics of different ores. The machine can collect the ore’s internal and external information simultaneously and with an AI algorithm, which can significantly improve the accuracy of ore sorting and better for sorting complex ores.

Compared with traditional ore sorting machines, which use a belt, the upgraded Insight Series utilises a vibrating feeder and short belt that leads to ore free fall, HPY Technology says. With the optimised mechanical design, the ore falls more evenly, avoiding ore overlap that affects recognition accuracy. In addition, the machine has various feeding widths (1,600 mm, 3,200 mm), which leads to processing capacities of 40-150 t/h (+10 mm-80 mm) to meet the needs of different mines needs during the beneficiation process.

As one of Asia’s largest lead and zinc mines, Fankou has taken steps to maximise the economic value of its process. Through the utilisation of sensor-based ore sorting, the company has seen significant increases in revenue and savings. Having worked with HPY Technology for over five years, Fankou looks to continue this partnership to further the research on the benefits of ore sorting machines. As HPY Technology continues innovating and revolutionising mineral processing, the benefits will only continue to grow, it says.

HPY Technology Co Ltd says it is a leader in the development and manufacture of ore sorting machinery, achieving excellent results in the ore sorting of tungsten, tin, antimony, lead, zinc, copper, molybdenum, gold, phosphate and over 30 other ore types, revolutionising the traditional mineral processing process and significantly promoting the technological progress of the global mining industry. With over 400 machines in use in over 100 mines, the company says it looks to continue revolutionising mineral processing.

Tungsten West cuts CAPEX with new Hemerdon feasibility study plan

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An updated feasibility study on Tungsten West’s Hemerdon project in Devon, England, has brought with it a processing re-optimisation program that includes a complete redesign of the front-end crushing circuit at the mine, a process that, it says, will considerably reduce the capital expenditure associated with this development.

The new study outlined average annual production of 2,900 t of WO3 in concentrate and 310 t of tin in concentrate over a life of mine of 27 years, along with an average steady-state mining rate of 3.5 Mt/y.

The changes to the existing process flowsheet to be implemented at Hemerdon can be categorised into three areas, namely:

  • Front end upgrades – new crushing, screening and ore sorting circuit required for Phase 1 (average of 2.4 Mt/y of granite ore, years 1-2);
  • Existing minerals processing facility modifications – upgrades to existing plant to accommodate production requirements for Phase 1; and
  • Phase 2 (3.5 Mt/y of granite ore, year 3 onwards) crushing and process plant expansion – future upgrades to both crushing and processing plants required for increased production rates, envisaged from year three onwards.

The re-engineering has mainly reduced capital and operating expenses around reduced ore handling costs by the introduction of direct tipping at a newly sited run of mine pad, incorporating the introduction of new semi-mobile primary jaw and secondary cone crushers, new operating parameters for the ore sorting circuit, and, to a lesser extent, changes to the existing dense media separation and fine gravity dressing circuits.

The revised front-end design also includes a significant tactical advantage through the introduction of a secondary crushed ore stockpile ahead of the ore sorters, Tungsten West said. This provides up to circa-40 hours of redundancy capacity to the crushing circuit, thereby de-coupling the front end crushing circuit from the minerals processing facility (MPF) – minimising downtime and maximising availability of the concentrator circuit.

Tungsten West has maintained the ethos of the original feasibility study in continuing to engineer-out as many operational, mechanical, electrical or ESG issues associated with the previous operation as possible and to ensure MPF availability and operability remains a priority, it said.

Back in July, Tungsten West concluded a re-evaluation of the options for bringing the Hemerdon mine back into production, announcing a new development plan that would re-optimise the March 2021 Bankable Feasibility Study. The plan was developed in response to global crises in power and diesel prices and the general inflationary environment for construction materials faced by the company.

The new plan has resulted in a remaining capital expenditure, including EPCM fees, of £31.1 million ($38 million) as of October 1.

Mark Thompson, Executive Vice Chairman of Tungsten West, said: “The feasibility study provides solutions to the energy price challenges and will enable increased operating efficiencies at the project. Key highlights from this study include a revised ore delivery and waste mining strategy, a split-phase approach to operational ramp-up to the full design specification, a new primary and secondary crushing method and location, a re-optimisation of the operating strategy for the X-ray Transmission ore sorters, re-design and re-engineering of the feed preparation, ore sorter buildings and structures, and a re-evaluation of the operation of unit processes and expected recoveries.

“We are build-ready at Hemerdon and we look forward to continuing to work with our partners and stakeholders to bring Hemerdon back into production in the fourth (December) quarter of 2023.”

Boston Metal to test molten oxide electrolysis tech on mining waste in Brazil

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Boston Metal, a global metals technology solutions company, says it will deploy its molten oxide electrolysis (MOE) platform technology to recover high-value metals from mining waste in Brazil.

The company’s wholly-owned subsidiary Boston Metal do Brasil and major Brazilian refined tin producer Mineração Taboca S.A. have signed an memorandum of understanding (MoU) to explore the use of Boston Metal’s MOE technology through a collaboration that, it says, seeks to advance the efficiency of metals production while demonstrating a sustainable and profitable solution for the mining industry. Mineração Taboca S.A produces not only refined tin, but other industrial minerals including niobium and tantalum.

Process development for the MoU will be performed at Boston Metal do Brasil, which opened in August, with construction underway on facilities in the municipality of Coronel Xavier Chaves near São João del Rei, Minas Gerais.

The company’s patented MOE technology uses electricity to selectively extract valuable metals from complex, low-concentration materials that are currently considered waste. This enables miners to reduce the financial and environmental liabilities of slag, by leveraging this natural by-product of metal production to create new revenue streams, Boston Metal says. Using renewable electricity, MOE can also be applied to convert all grades of iron ore into emissions-free steel, according to the company. Once this groundbreaking technology becomes commercially available by 2026, steel producers will be able to cost-effectively achieve net zero scope 1 and 2 emissions and meet growing global demand for green steel.

Itamar Resende, President of Boston Metal do Brasil, said: “MOE provides the metals industry with a more efficient, lower cost and greener solution to produce a variety of metals and alloys from a wide range of feedstocks. We’re looking forward to further developing our high-value metals business and demonstrating the efficiency of our MOE solution to transform mining waste into sources of revenue.”

Boston Metal expects commercialisation of the MOE technology for high-value metals to take place in 2023.

EPC-UK’s rock-on-ground services team heading to Hemerdon tungsten-tin project

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EPC-UK says its full rock-on-ground services will soon begin work at the Hemerdon tungsten-tin deposit in Devon, England, as part of a new contract it has secured.

The company’s work will begin in 2023 and will enable operator, Tungsten West Ltd, to benefit from EPC-UK’s skilled level of drilling and blasting expertise as it sustainably extracts specific critical minerals, it says.

The reopened Hemerdon mine comprises the world’s third largest tungsten mineral resource, with a recently-released mining plan envisaging restarting production during the first half of next year.

In terms of mining, Hemerdon will aim to process 2.1 Mt of ore in year one, 2.6 Mt in year two, before ramping up to steady-state production of 3.5 Mt throughput in year three. This targets WO3 in concentrate production of 2,200 t, 3,000 t, 3,900 t, and tin in concentrate production of 320 t, 430 t and 600 t in years 1, 2, and 3 respectively.

In advance of EPC-UK’s rock-on-ground service commencement on site, it has agreed a program of early investment in the Tungsten West project, which has allowed us to fully understand the operation’s requirements and meet the project’s needs, including, among other things, the use of the latest equipment.

This will see the company deliver new Epiroc drilling rigs fitted with autosampler capabilities for drill returns.

Explosive supply to site will also benefit from EPC-UK’s latest smart truck technology supported by the full Vertex software package, which can incorporate drone gathered data and GPS capabilities to refine and improve blast performance, assess against incremental changes in design and subsequently optimise results for customers, the company says.

In terms of digital services, EPC-UK plans to use its digital techniques and engineering expertise, together with subsequent blasting operations, to enable the most efficient ore extraction to realise the most value possible, it said.

Ben Coppock, General Manager Blasting and Explosives at EPC-UK, explained: “We’re keenly anticipating our delivery start date at Hemerdon and look forward to realising results from our joint agenda with customer, Tungsten West. Our business ethos, commitment to safety and levels of expertise are aligned, and we will work successfully and sustainably to meet our mutual greener goals.”

James McFarlane, Managing Director of Tungsten West, said: “Tungsten West has full confidence in EPC-UK as a drilling and blasting rock-on-ground provider. The preparations the team has already put in place in advance of contract work commencing is impressive and demonstrates complete customer focus and a commitment to achieving leaner operations. The reopening of the Hemerdon Mine and its promise to bring sustainable economic activity back to the area is a significant development and we anticipate the results that EPC-UK and Tungsten West will deliver.”

Zinnwald striving for battery-electric circularity with lithium project development

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The development of the integrated Zinnwald lithium project in Germany could see the incorporation of a battery-electric fleet of LHDs and the return of metal production to a region of saxony with mining history dating back to the Middle Ages.

The London-listed owner of the project, Zinnwald Lithium Plc, has just released a preliminary economic study on its namesake project focused on supplying battery-grade lithium hydroxide to the European battery sector.

As with any responsible battery metal project being developed today, the project’s ‘green credentials’ are being considered even at this early stage.

Zinnwald Lithium has been keen to flag these, mentioning the project is located close to the German chemical industry, a fact that should enable it to draw on a well trained and experienced workforce with well-developed infrastructure, plus reduce the ‘carbon footprint’ of the final end-use product.

This focus will see all aspects of the project – from mining through to production of the end product – located near to the deposit itself.

Zinnwald Lithium also said the project has the potential to be a low- or ‘zero-waste’ project, as the vast majority of both its mined product and co-products have their own large-scale end-markets.

This could see it produce not only battery-grade lithium hydroxide monohydrate products, but sulphate of potash (SOP) for the fertiliser market and precipitated calcium carbonate (PCC) – the latter being a key filling material in the paper manufacturing process.

The project now includes an underground mine with a nominal output of approximately 880,000 t/y of ore at an estimated 3,004 ppm Li and 75,000 t/y of barren rock. Processing, including mechanical separation, lithium activation and lithium fabrication, will be carried out at an industrial facility near the village of Bärenstein, near the existing underground mine access and an existing site for tailings deposition with significant remaining capacity.

With a 7-km partly-existing network of underground drives and adits from the ‘Zinnerz Altenberg’ tin mine, which closed in 1991, already mapped out, the bulk of ore haulage is expected to be via either conveyor or rail

The nominal output capacity of the project is targeted at circa-12,000 t/y LiOH with circa-56,900 t/y of SOP, 16,000 t/y of PCC, circa-75,000 t/y of granite and 100,000 t/y of sand as by-products.

The company is looking to complete the ‘circularity’ dynamic in its fleet and equipment selection, according to CEO, Anton Du Plessis, who mentioned that electric LHDs could be used to load and haul ore to an ore pass in the envisaged operation.

He said the cost estimates to use such equipment – which are factored into the project’s $336.5 million initial construction capital expenditure bill – have come from Epiroc, which has a variety of battery-operated mobile equipment.

“The base case is battery-operated loaders,” he told IM. “The final selection will be based on an optimisation study where, in particular, partly trolley-fed haulage systems will be investigated.”

Forms of automation are also being studied, Du Plessis said, with the caveat that “only select technologies we consider proven” will be evaluated.

Zinnwald Lithium is also looking at electric options for long-hole drilling underground, with both battery-based units and cabled versions under consideration and requiring firming up in the optimisation study.

With a 7-km partly-existing network of underground drives and adits from the ‘Zinnerz Altenberg’ tin mine, which closed in 1991, already mapped out, the bulk of ore haulage is expected to be via either conveyor or rail. The former, of course, will be powered by electricity, but the company is also considering potential battery-electric options for the latter, according to Du Plessis.

The company is blessed with existing infrastructure at the mine, which should help it in advancing the project at the pace its potential end-use manufacturing suppliers would like. It is already evaluating options for the construction stage – with an engineering, procurement and construction management contract the most likely option – and it has plans to conclude a feasibility study by the end of next year.

Du Plessis said while most of the fixed assets have been removed or were deemed outdated a long time ago from the former operating underground mine, other infrastructure was in good shape.

“The excavations, main level, underground workshop, ventilation shafts and, particularly, 2020 refurbished access tunnel provide a very good starting point for our project,” he said. “The access tunnel was originally constructed for dewatering the old mine and, therefore, the mine and the tunnel have been maintained very well.”

The company is now shifting to the bankable feasibility study and currently selecting partners for the project.

With what it calls a “simple, five-stage processing” route confirmed by test work for the extracted material at Zinnwald, the company is looking to select OEMs with the optimal concept for the project, Du Plessis said.

“In the PEA, mineral processing equipment cost is based on Metso Outotec estimates, pyrometallurgy is based on Cemtec technology, and hydrometallurgy is based on various providers’ technology,” he clarified.

Orica’s WebGen wireless initiation system helps unlock reserves at BMTJV Renison tin mine

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The Bluestone Mines Tasmania Joint venture (BMTJV) says it has become the first company in the Tasmania mining sector to demonstrate Orica’s fully wireless initiating system, WebGen™.

Since early 2021, BMTJV, the owner of the Renison tin mine, has been in consultation with Orica to implement the WebGen wireless blasting technology.

The first WebGen blast was successfully loaded in the Central Federal Basset (CFB_1458_5990_F4) section of the mine on June 13, 2022, with the first wireless blast in Tasmania successfully fired at BMTJV over the mine’s leaky feeder system on June 19.

Some 107 WebGen primers were loaded into BP4 (Block Panel 4) and “slept” for 14 days while BP3 was charged and fired, the company explained. Due to the geometry of the blast – and it being a high seismicity area – for B4 to be mined conventionally, a further 60 m of development would have been required to recover this ore.

The Orica WebGen system includes an i-kon™ plugin detonator, a Pentex™ W booster and a DRX™, which is a digital receiver comprising a multi-directional antenna and a battery that serves as the in-hole power source.

The Encoder Controller individually programs each wireless primer with its own unique encrypted codes. This encoder contributes to the inherent safety of the system, and programs each wireless primer with two codes, BMTJV explained. The first code is a unique group identity number for exclusive use at each mine and assigned to specified groups of primers which will sleep, wake and fire together. The second code is a ‘delay time’ specific to the wireless primer and blast design.

Mark Recklies, Chief Operating Officer – BMJTV, said: “WebGen has now been used to support continual safety improvements and deliver savings across the working mine.”

Tungsten West breaks ground at Hemerdon for TOMRA XRT ore sorters

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Tungsten West says it has broken ground at its Hemerdon tungsten-tin mine in Devon, England, with the first sod turned for the installation of the TOMRA X-ray Transmission (XRT) sensor-based ore sorters.

This event, the company says, marks another major step in the company’s upgrade and refurbishment plans for the project’s processing plant.

Hemerdon is, Tungsten West says, the third largest tungsten resource globally, as well as being a previously producing mine that was operational from 2015-2018. Tungsten West purchased the Hemerdon Mine in 2019, and has since completed a bankable feasibility study that demonstrated an extensive reserve of approximately 63.3 Mt at 0.18% W and 0.03% Sn, as well as 37.4 Mt of saleable aggregate material. The company estimates that the life of mine is currently 18.5 years with the opportunity to extend this through future investment.

As announced earlier this month, the company took receipt of important long-lead equipment items, including the seven XRT ore sorters, which will make up part of the upgraded equipment the company plans to install into the front end of the processing plant. The XRT ore sorter will substantially improve and streamline operations once production restarts, minimising plant downtime, increasing recovery as well as a host of ESG benefits, it said.

After significant test work, Tungsten West engaged TOMRA to supply the seven units that are required to treat the run of mine throughput. This consists of six duty units and one standby unit. Orders and deposits for these units were placed in 2021 and the units have now been delivered to the UK and await final transfer to Hemerdon where they will be installed in the front end of the processing plant.

Additionally, the company is pleased to announce the appointment of James McFarlane as Managing Director of Tungsten West. McFarlane previously held the position of Technical & Operations Director of the company.

Max Denning, Tungsten West CEO, said: “We are extremely excited to have broken ground at Hemerdon this week, marking an important milestone in the project’s restart. Ensuring the UK and the western hemisphere have got access to two key critical minerals has never been more profound. We are also delighted to announce James as our new Managing Director; his extensive experience will prove invaluable in the company’s development as we move closer to first production at Hemerdon.”

Tungsten West makes EPCM progress at Hemerdon as TOMRA XRT ore sorters hit the road

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Tungsten West has named Fairport Engineering Limited as its engineering, procurement and construction management (EPCM) contractor at the Hemerdon tungsten-tin project, in the UK, as well as confirmed it was soon expecting to receive seven X-ray Transmission (XRT) sensor-based ore sorters from TOMRA.

Since successfully listing on the AIM Market of the London Stock Exchange, Tungsten West has been advancing the development of Hemerdon, which is one of the most advanced mining projects in England and is expected to be a key future global supplier of tungsten and tin.

Hemerdon is, Tungsten West says, the third largest tungsten resource globally, as well as being a previously producing mine that was operational from 2015-2018. Tungsten West purchased the Hemerdon Mine in 2019, and has since completed a bankable feasibility study that demonstrated an extensive reserve of approximately 63.3 Mt at 0.18% W and 0.03% Sn, as well as 37.4 Mt of saleable aggregate material. The company estimates that the life of mine is currently 18.5 years with the opportunity to extend this through future investment.

On top of the ore sorters, Tungsten West said the rest of the long-lead items had been ordered and were scheduled for delivery within the company’s timetable. It plans to recommence mining this year.

The upgrade and refurbishment of the existing processing plant at Hemerdon is centred around the optimisation of the existing concentrator circuit as well as the introduction of a new crushing and screening circuit that will then feed into a new XRT ore sorting stage. These upgrades will streamline processing, minimise plant downtime and improve recovery rates, according to the company.

After significant test work, Tungsten West engaged TOMRA to supply the seven units that are required to treat the run of mine throughput. This consists of six duty and one standby units. Orders and deposits for these units were placed in 2021 and the units have now been delivered to the UK and await final transfer to Hemerdon where they will be installed in the front end of the processing plant.

On top of this, six new screens and 11 vibrating pan feeders have been ordered from Vibramech of South Africa at fixed prices. These will replace the existing large screens, which caused the low frequency issues, and were a key contributor to plant downtime under Wolf Minerals – the previous owner of Hemerdon. Delivery is expected in the June quarter of 2022.

Max Denning, Tungsten West CEO, said: “We are extremely pleased with progress at site, particularly the onboarding of Fairport Engineering to undertake the detailed design and construction of the project. We are looking forward to working with Fairport as we move towards restarting full production at Hemerdon, with a substantially improved processing route, through the introduction of XRT ore sorting and upgraded processing equipment. The company has assembled a strong projects and operations team, and we remain confident in our progress.”

TOMRA Mining’s ore sorting solution helps Renison tin mine do ‘more with less’

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TOMRA Mining and its X-ray Transmission (XRT) technology has, the company says, provided an effective solution for the extreme conditions at the Bluestone Mines Tasmania JV (BMTJV) Renison tin mine in Tasmania, Australia, with sensor-based ore sorting solution unlocking significant value and delivering environmental benefits.

The Renison mine is 50% owned by Metals X through the BMTJV, and is the only major tin mine in production in Australia with a mining rate of close to 1 Mt/y, according to TOMRA. While slated capacity is 1 Mt/y, the concentrator is restricted to 750,000 t/y.

The mine’s extreme humidity and highly acidic processing water (pH around 4.5) create unique challenges for the sorting process, the equipment and waste management, according to TOMRA.

A complex flowsheet

The underground mine operates a primary crushing system before the material is transported to the surface through a shaft. Once there, it enters the pre-concentration plant, where it undergoes a three-stage crushing, screening and cleaning process. The particles are split into two fractions – 10-25 mm and 25-60 mm – which are fed into two TOMRA XRT sorters. The output consists of two streams: the product, which is transferred to the wet plant, and the waste, which is fed into a TOMRA EM sorter to separate acid-forming sulphides from this waste stream.

In the wet plant, the product goes through primary grinding followed by bulk sulphide flotation. The tailings are processed downstream to concentrate the cassiterite tin mineral through gravity concentration; gravity tails are further treated via desliming and tin flotation. The combined concentrates are fed to a leaching circuit to remove carbonate minerals. After a final wash stage, the concentrate is de-watered and dispatched.

BMTJV approached TOMRA to address two key requirements at the plant. The first was the need to upgrade the tin feed to the plant, as Ben Wraith, Principal Project Metallurgist at BMTJV (pictured below), explained: “The Renison tin operation wanted to achieve economies of scale, putting more tonnes through the front end of the plant without upgrading the back end downstream – we wanted to do more with less.”

The second requirement was to address the environmental issue of removing acid-forming sulphides from the waste.

Following site visits and extensive discussions with BMTJV’s teams, TOMRA proposed a solution that addressed the tin feed quality with two COM Tertiary XRT 1200 sorters and the waste issue with a COM Tertiary EM 1200 sorter. A team from BMTJV visited the TOMRA Test Center in Sydney, Australia, where they observed what the XRT sorter operating at capacity is capable of.

Gavin Rech, Technical Manager at TOMRA, said: “Our XRT stands out for the high spatial and density resolution and its ability to do contrast sorting, identifying fine high-density tin inclusions in the ore with an accuracy that has no equal on the market. On top of that, it can separate it from the acid-forming sulphides, so that we have the ability of pulling the tin into the first product and sending the rest to the EM sorter.”

Gavin Rech, Technical Manager at TOMRA

The two COM Tertiary XRT 1200 sorters went into operation in 2018. Initially, BMTJV’s strategy focused on low reject grades, devoting less focus to achieving the mass reject rate and overall process plant throughput. However, the specific conditions at the Renison mine affected the results achieved. The large variance in run of mine (ROM) particle size distribution resulted in insufficient stability in the feed to the circuit. In addition, the extremely wet conditions in west Tasmania and consequent high ambient moisture content, combined with the high moisture of the ore delivered from underground, further affected the sorting process.

In 2019, a new investigation was conducted into the ore sorting performance and led to a change of direction, where the operation shifted away from targeting low reject grades, towards sorting as aggressively as possible, according to Wraith, moving from a “tin recovery-based” operating strategy to a “mass reduction” one.

“We are getting 20-25% mass reduction, so 75-80% of the materials are going into the wet plant, and we are still achieving 97-98% tin recovery overall across the crushing circuit,” he said. “Pre-concentration didn’t materially impact overall recovery because the tin in the material that is rejected as waste is extremely fine grained and a proportion is associated with sulphides, so it wouldn’t have been fully recovered in the downstream wet plant and would have been lost to tailings.”

This approach, he said, is best for Bluestone’s application as it provides the ability to process 15-20% more tin units without having to upgrade the downstream concentrator.

Wraith added: “Operating the sorting circuit has slightly increased our overall processing cost, but this is more than offset by the large increase in ROM throughput by 15-20% and, thus, tin production, so the unit cost per tonne of tin produced is reduced by almost 10%. We’ve broken multiple production records in the last year in tin units, and this gives us confidence in what we can achieve because the machine performs over and over again if you treat it right and if you prepare your feed correctly.”

TOMRA XRT success leads to upgrade decision

In view of the results achieved with the two TOMRA XRT sorters, BMTJV decided to upgrade the ore sorting circuit with two new, recently launched XRT models with stainless steel internal parts and advanced features such as the TOMRA ACT user interface and the TOMRA Insight cloud-based platform, according to TOMRA.

“The decision to buy new machines was easy,” Wraith said. “The stainless steel will assist prolonging the TOMRA sorter’s life by protecting the unit from our high-moisture and corrosive environment. The more ergonomic design will help our maintenance teams, which is particularly important for machinery operating in these harsh conditions.”

Wraith said the use of TOMRA Insight, the ore sorting company’s subscription-based service that relays and analyses machine data, will “enhance everybody’s understanding and experience of the machines”.

He added: “It will be more of an analytical platform for our metallurgy and maintenance staff, providing ample opportunity to gain valuable information that can be analysed and optimised over time. The one feature I am personally interested in is the particle size monitoring through the machines, which will enhance our overall circuit performance because we have an integrated circuit with the crushing and screening plant. Feed preparation is key to maintain a consistent performance – knowing how well you’re preparing your feed in a live fashion can only end up with a better result.”

TOMRA will also be able to log into the machine and check the daily reports generated by TOMRA Insight, so its technical teams will be prepared ahead of site visits for maintenance or optimisation.

Wraith concluded: “TOMRA has been working with the site maintenance team to tailor solutions to our operating environment, which has been invaluable. TOMRA supported me through site visits, which included equipment inspections, site-based training of our personnel, and an openness to continually improving the technology and finetune it to our site-specific requirements. They assisted the site with troubleshooting, optimisation, discussing the nuts and bolts of the issues as they arose, and finding a solution that works.”

GR Engineering to build paste plant at Renison tin operations

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GR Engineering Services Ltd says it has been awarded additional work by Bluestone Mines Tasmania Pty Ltd with a combined value of A$31.7 million ($23.6 million).

This work, to be performed by GR Engineering’s team in Queensland and Tasmania, Australia, includes an engineering, procurement and construction (EPC) contract involving the design, supply installation and commissioning of a new paste backfill plant and associated infrastructure at its Renison tin operations.

Early front-end engineering design work on the paste plant has been completed, GR Engineering said. The value of this project is A$23.9 million.

The Environment Protection Authority signed off on this paste plant build in August. It will redirect tailings from the existing tin process plant for dewatering and processing into filter cake, with the filter cake to then be stored and combined with cement in a batch process before being piped underground to stabilise mined out areas of the underground operations.

In addition, the company has been awarded an EPC contract for the HV Power Upgrade Project that includes the design, supply and installation of new transforms and HV switchgear for Bluestone’s existing main switchyard. The HV Upgrade Project has commenced, and the value of this work is A$7.8 million, the contractor said.

Geoff Jones, Managing Director, said: “GR Engineering has been pleased to support Bluestone Mines on multiple projects over the last two years and has developed a strong working relationship with management and the on-site team. We look forward to continuing our work with Bluestone Mines using GR Engineering’s team in Queensland and Tasmania.”

The Renison tin operations are owned 50:50 by Yunnan Tin Group and Metals X through the Bluestone Mines Tasmania Pty Ltd joint venture.