Tag Archives: high pressure grinding rolls

Metso books €12 million worth of high pressure grinding roll spare part orders

Metso says it has received several orders for the supply of HRC™ Series high pressure grinding roll (HPGR) replacement tyres in the US, with the scope of supply including five replacement tyres with studs and another order for a spare reducer for a Metso HRC 3000.

The value of the orders amounts to more than €12 million ($13 million), the OEM says.

Rodrigo Rizzoli, Vice President, Stirred Mills & HPGR Services, Metso, said: “This milestone not only marks our growing success but also highlights the fact that customers trust Metso’s spare parts to ensure equipment performance and reliability. Our customers will benefit from the proven technology optimising their operations and simultaneously eliminating potential grinding challenges for long-term sustainability.”

Last month, Metso announced it is strengthening its service capability by expanding its service centre in Arizona and by establishing a training centre to improve competence development in the region to support the growing needs of mining customers. This investment not only improves the capacity, but also the ability to perform heavy equipment maintenance and service a wide range of equipment, HPGRs included.

The HRC HPGR is a part of Metso’s grinding portfolio. Metso’s HPGR has been proven to improve energy efficiency by up to 15% and decrease recirculating loads by up to 24%, the company says.

Weir and Swiss Tower Mills align on energy efficient comminution pathway

The Weir Group has announced a new alliance with Swiss Tower Mills Minerals (STM) in which Weir will market STM’s vertical stirred grinding mills for coarse grinding applications worldwide.

Integrating vertical stirred grinding mills into Weir’s minerals processing flowsheet will provide customers substantial improvements in throughput and energy efficiency, helping them to meet their productivity and sustainability goals, Weir says.

STM’s vertical stirred grinding technology is proven for energy efficient comminution in the mining market with more than 80 units currently operating in the hard-rock mineral processing industry across the globe, according to the company. It is used within the comminution segment of the minerals processing circuit as part of a series of crushing and grinding processes that create the fine particles from which minerals can be extracted through flotation.

Comminution, as has been well documented, is one of the most energy intensive parts of the mine, accounting for 25% of the final energy consumption of an average mine site.

Weir says it is already a leader in comminution technologies, offering solutions such as Enduron® high pressure grinding rolls (HPGRs) to drive down energy consumption by around 40% for customers.

This new alliance with STM takes things to the next level, offering the mining and minerals industry a proven low energy alternative to traditional high energy consuming tumbling mills, it said. Combining and integrating these energy-efficient technologies into a single, optimised flowsheet will deliver significant reductions in energy use, driving down costs and carbon emissions.

In order to prove the most beneficial flowsheet for specific projects, STM has already supplied two vertical test mills to the Weir Minerals HPGR test facility in Venlo (Netherlands). This will put Weir and STM in the unique position to provide clients combined energy efficient grinding test work of HPGR followed by STM’s vertical stirred mill, they said.

Ricardo Garib, Weir Minerals Divisional President, said: “Weir and STM share the same vision of enabling primary resource providers to produce resources in the most sustainable manner. This is a perfect match of best-in-class technology providers. Integrating STM mills with Weir’s comminution products, which includes Enduron HPGRs and Enduron screens, will improve throughput and help bring substantial reductions in carbon emissions.

“This is a real win-win.”

Fritz Moser, STM Chairman, said “Both the HPGR and the STM vertical stirred mills provide significant energy savings compared to conventional grinding technologies. Our new supply agreement with Weir will enable us to fast track the roll out of an innovative flowsheet using STM mills in conjunction with Weir’s Enduron HPGR.”

SKF addresses service life of large sealed bearings for HPGRs with Explorer SRBs

SKF says it has extended its range of large bearings for roller presses, with a sealed version that prolongs service life in equipment such as high pressure grinding rolls (HPGRs).

Its Explorer spherical roller bearings (SRBs) in the 241 series are now available up to 1,250 mm bore, with this series and sizes commonly used in HPGRs in cement and mining operations.

“Using sealed bearings is the best way to increase mean time between failures,” Daniel Ortega, Product Line Manager for Sealed SRBs at SKF (pictured), says. “It is a long-term investment that increases machine availability and reliability.”

The new version – which is sealed on both sides – offers up to double the lifetime of an open bearing and has shown in tests that it reduces grease consumption by up to 99%, SKF says.

In a HPGR, four large spherical roller bearings are usually used. During a maintenance interval of three months, normally 540 kg of grease is used for certain sizes. With sealed Explorer spherical roller bearings, only 7 kg of grease is needed during the same interval, according to the company, reducing both cost and environmental impact.

In addition, the sealed SRB can be remanufactured twice, which further extends service life. This raises productivity and machine availability while lowering total cost of ownership.

The new bearing has been redesigned to have a higher load-carrying capacity. Bearings with a bore diameter below 1,000 mm have an HNBR seal that is retained by a snap ring. Larger bearings use a G-ECOPUR seal that is bolted to the bearing’s outer ring.

The sealed bearing can be used on its own, or as part of an SKF three-barrier solution.

Roller press bearings often wear out because ineffective sealing leads to lubricant contamination. The sealed bearings overcome this problem – and this delivers several advantages, SKF says:

  • First, bearing failure relates to more maintenance interventions, which carries a higher risk of accident and injury and expensive shutdowns;
  • The new design also offers a maintenance benefit. Rather than stopping production for preventive maintenance of the bearing, the wear of the roller press roller determines when a service is needed; and
  • The bearings are available with short delivery times – even in the largest sizes.

Enter Engineering, thyssenkrupp to tackle Tebinbulak iron ore deposit in Uzbekistan

Enter Engineering and thyssenkrupp AG have signed an Agreement of Intent that could see the engineering procurement and construction (EPC) contractor take the exclusive role as construction partner in building an integrated mining metallurgical complex at the Tebinbulak iron ore deposit in Uzbekistan.

The pact, worth €50 million ($58 million), comes on top of a signed agreement for the start of preparatory work on the project, including a contract for the supply of equipment, its design, supervision during installation and commissioning at the facility.

The high pressure grinding roll (HPGR) technology will be used to help process up to 60 Mt/y of iron ore, according to the EPC firm.

The implementation period for Enter Engineering’s construction role is two years with the plant launch anticipated for September 2023.

Bakhtiyor Fazylov, Chairman of the Board of Directors of Enter Engineering, said: “We are delighted to partner with a leading global company such as thyssenkrupp. Applying German standards, we will create a high-quality raw material base for the domestic metallurgical industry. This project also embodies all the goals Enter Engineering strives for: protecting Uzbekistan’s national interests in the international market, supporting the interests of domestic consumers and creating jobs.”

Reza Poorvash, CEO thyssenkrupp Mining Technologies Europe and Asia, said: “To date, more than 140 units of HPGR equipment have been sold in the mining industry. In the CIS countries, thyssenkrupp takes a leading position among mining companies that use this technology, in practice confirming the high quality and reliability of the German brand.”

Roman Karl, Managing Director thyssenkrupp Mining Technologies CIS, added: “We are delighted to partner with such a well-known company in Uzbekistan as Enter Engineering, who have a long track record of successful execution in major engineering construction projects.

“The project will use one of the most energy efficient and innovative technologies to significantly reduce energy consumption. HPGR has been used since 1985 in the cement industry, and since 1986 in the mining industry for use in the grinding process to ensure a high level of product fineness. Full integration of this technology within Industry 4.0 is also important.”

The Tebinbulak complex is significant for Uzbekistan because of its multiplier effect. As well as creating new jobs in remote areas, it will help develop domestic iron ore to provide the country’s existing metallurgical complexes with raw materials. It will also support development of infrastructure, creation of service enterprises and an increase in trade between countries.

Tebinbulak is located in the Karauzyak district of Karakalpakstan, in the north-west part of Uzbekistan. The field covers 5.2 sq.km and comes with a predicted mine life of 27 years.

Cooperation between Enter Engineering and thyssenkrupp is supported at a high inter-governmental level, with the agreement signing ceremony attended by Alisher Sultanov, Uzbekistan’s Minister of Energy.

Swiss Tower Mills Minerals backs Coalition for Eco-Efficient Comminution

Swiss Tower Mills Minerals AG (STM) has become the latest sponsor to support the work of the not-for-profit Coalition for Eco-Efficient Comminution (CEEC).

An innovative company that has successfully translated the vertical stirred milling technology of industrial minerals to hard-rock minerals processing, STM’s support of CEEC’s work was a natural fit for the company, according to Managing Director, Ralf Hesemann.

“The uptake of new technology in the mining industry is traditionally a slow process,” Hesemann said. “Tapping into a trusted independent body that communicates the latest technical findings on efficient comminution practices is a win-win for both of us.

“I look forward to our collaboration.”

Swiss-based STM developed the Vertical Regrind Mill (VRM) and released it to the minerals market in 2012. More than 60 of the stirred media grinding mills have been sold to mines across the Americas, Europe, Africa, Asia and Australia. For fine and ultra-fine grinding applications, it is marketed under the name HIGmill, through the exclusive partner Metso:Outotec. For coarse regrind applications, STM offers the VRM mill directly to customers in the minerals market.

Since the grinding principle of multi-compartment grinding offers substantial energy savings, a new stirred mill has been developed for coarse grinding applications up to 6 mm feed size, the Vertical Power Mill™ (VPM). Mill sizes range from 700 kW to 12,500 kW with high flow rates, and potential energy savings of up to 40%. Due to its small footprint, STM is marketing the VPM as a viable ball mill replacement in HPGR circuits or for capacity increase in existing plants.

The energy savings are achieved through uniquely designed rotors and stator rings in a vertical arrangement that enable high power intensities, even with relatively low tip speeds, STM says. This results in higher energy efficiency, a smaller footprint and the potential for increased recoveries. Power intensities of 200-300 kW/cu.m are typical, and operational tip speeds range between 6-12 m/s, depending on application and mill size.

CEEC Director, Chris Rule, said it was encouraging to see energy efficient, stirred media mills being installed by industry as a step towards more sustainable mining practices, in line with ESG considerations and net zero emissions commitments.

One of the first HIGmills be commissioned, in 2015, was a 700 kW mill for a copper concentrate regrind application at the Kevitsa mine in Finland. Several papers have been published on the energy efficiency and metallurgical performance of this mill, including an Outotec paper presented at Comminution Capetown 2016, and ‘A Review of Published Full-Scale Stirred Mill Results’ by Michael Larson, Molycop, USA, presented at the SAG 2019 Conference.

The technology will also be installed at the Iron Bridge Magnetite Project in Western Australia. The joint venture between Fortescue Metals Group and Formosa Steel IB Pty Ltd is the world’s first large-scale plant without horizontal milling. The flowsheet consists of a two-stage HPGR circuit feeding in total 10 advanced HIGmill grinding mills.

Rule said stirred mill grinding technology had been well proven for decades in industrial mineral applications such as in the opacifiers, fillers, ceramics, paint and pharmaceutical industries.

“We commend STM for translating this technology to mineral processing, offering miners an energy-efficient, low footprint alternative to high-intensity ball milling,” Rule said.

“Having STM on board as a CEEC sponsor means greater opportunities for us to learn about and share alternative comminution approaches. This support from our valued sponsors over the past 10 years is what enables CEEC to help keep industry aware of demonstrated advances that help mining leaders tackle the challenges of reducing the energy consumption, emissions and overall footprint of their operations.”

Hesemann said declining ore quality meant energy efficient comminution was becoming a more critical stage for realising profit.

“We’re proud of the part our technology plays in lowering the footprint of mineral processing, while at the same time decreasing capital expenditure and operating expenditure and improving the bottom line.

“Being a CEEC sponsor will enable us to more widely share any advances in this field, as well as learning from the global network of industry experts that CEEC brings together through its events and online resources.”

Pictured is the factory acceptance test success for a new 50,000 litre Vertical Regrind Mill (VRM50000)

NioCorp working with Weir Minerals, NRRI on Elk Creek HPGR test work

NioCorp Developments Ltd is to initiate testing of Elk Creek project ore using high pressure grinding rolls (HPGR) technology from Weir Minerals.

HPGR technology is considered an energy efficient and low-emission alternative to conventional processing for reducing the size of the ore to enable the recovery of niobium, scandium, titanium, and potential rare earth products, NioCorp said.

The use of this technology in the project reinforces the company’s commitment to the environment and designing a sustainable operation, it added.

The testing is being conducted at the Natural Resources Research Institute (NRRI) of the University of Minnesota-Duluth, in partnership with Weir Minerals. During the testing, which is expected to take several weeks, around 3 t of Elk Creek drill core will be reduced to the 1-mm size needed for hydrometallurgical test work.

Working with Weir Minerals, NRRI acquired an industrial-scale Enduron® HPGR to carry out testing on a variety of ores with this process back in 2020. This is the only large scale HPGR dedicated to research in the US, NRRI claims.

“The network is expected to provide key data that will be used to properly size the HPGR unit for the potential ore throughput at the Elk Creek project, once project financing is secured and the project is operational,” NioCorp said.

The company is currently evaluating the next steps in its overall metallurgical test work program, which will focus on optimising and streamlining the existing processing flowsheet as well as establishing process routes for the potential recovery of rare earth products. The rare earth products that are of most interest to the company are, at present, neodymium-praseodymium (NdPr) oxide, terbium oxide and dysprosium oxide. As previously announced, the company has launched a review of the economic potential of expanding its currently planned product suite from the project to also include rare earth products.

An April 2019 feasibility study on Elk Creek, in Nebraska, USA, estimated average production of 7,220 t/y of ferroniobium, 95 t/y tpa of scandium trioxide and 11,642 t/y of titanium dioxide over the 36-year mine life.

Scott Honan, NioCorp COO, said: “After witnessing testing at NRRI, I was impressed with how the HPGR was able to handle the Elk Creek ore quickly and efficiently, with minimal noise and dust.

“We look forward to completing this phase of the test work and moving on to look at further improvements to the existing flowsheet, including our new emphasis around the rare earths.”

Los Andes Copper commits to HPGR comminution route for Vizcachitas

Los Andes Copper says additional comminution test work has confirmed the selection of high pressure grinding rolls (HPGR) circuit technology for use in the processing circuit at its Vizcachitas copper project in Chile.

The use of HPGR, and the adoption of the previously announced dry-stack tailings, reinforces the company’s commitment to the environment and designing a sustainable operation with low energy and water consumption, it said.

At early stages of the Vizcachitas prefeasibility study (PFS), HPGR technology had been identified as the most attractive grinding alternative, given the data obtained from preliminary test work conducted in 2009, and in 2017-2018. As part of the PFS metallurgical test work, four representative samples from the mine plan were sent to a laboratory for pressure bed testing. The results of this test work confirmed the equipment sizing and its performance for a PFS-level study.

The results provided specific energy consumption readings of 2.17 kWh/t in the case of a HPGR circuit, which results in a global specific energy consumption of the comminution circuit of approximately 14 kWh/t. As compared with the semi-autogenous grinding alternative, the HPGR showed a reduction of up to 20% in energy and up to 50% in grinding media consumption, Los Andes Copper said. These results confirm the advantages of adopting this technology at the project.

The comminution circuit at Vizcachitas, where the HPGR circuit will be incorporated, is a three-stage crushing circuit using a gyratory primary crusher, three cone crushers in open circuit and two HPGR as a tertiary stage arranged in a closed circuit followed by ball mills. Through this process, and in addition to the lower energy consumption, the use of HPGR will reduce dust emissions related to dry crushing due to the removal of coarse recirculation in the secondary crushing stage, the company said.

Fernando Porcile, Executive Chairman of Los Andes, said: “I am pleased that the results from the test work carried out to date have confirmed the advantages of using HPGR in terms of enhancing project economics, lowering energy consumption and increasing operational flexibility.

“The use of HPGR technology favours the stability of the dry stacked tailings operation, as well as reducing the environmental impact by minimising energy usage, water consumption and dust emissions.”

Metso Outotec delivers ‘next evolution’ in high pressure grinding rolls with HRCe

Metso Outotec has launched the “next evolution of the high pressure grinding roll”, with the delivery of its HRC™e HPGR.

The original HRC HPGR was launched back in 2014 by Metso (now Metso Outotec), pioneering the use of flanges and non-skewing design. The grinding performance that brings energy efficiency, lower circulating loads and increased throughput is now strengthened with an additional evolution in design, Metso Outotec says.

The new HRCe comes with a decreased installation capital expenditure compared with the original HRC. Changes in design allow for maximum productivity with proven technology that leads to superior grinding efficiency.

Christoph Hoetzel, Head of Grinding business line at Metso Outotec, said: “We are very excited about the new HRCe, which combines proven technology and customer-focused evolutions. Metso Outotec is the only OEM that has been able to design and develop reliable flanged HPGR technology that has demonstrated superior performance for many years in the mining industry. We will continue utilising our proven technology but have evolved the design to maximise value for our customers and superior grinding efficiency.”

The high throughput comes from the elimination of the edge effect with the flange design, which will ultimately maximise the amount of crushed material, the company says. With the anti-skew assembly, customers will find faster restarts and no downtime from skewing events, according to Metso Outotec.

The HRCe also comes with a large feed size acceptance of 60-120 mm and improved energy efficiency compared with similar HPGRs, the company says. It also boasts typical capacities of 1,810-6,930 t/h.

Key benefits of the new HPGR include:

  • Improved energy efficiency of up to 15%;
  • Lower circulating load of up to 24%;
  • Increased throughput of up to 19%;
  • Elimination of edge effect from combination of proven flange design and anti-skew assembly; and
  • Elimination of downtime caused by skewing events.

thyssenkrupp navigates South Africa lockdown to replace platinum mine HPGR roll

As the COVID-19 pandemic tightens its grip, thyssenkrupp Industrial Solutions says it is assisting customers in maintaining operational efficiencies through sustainable service delivery and innovative technologies.

“The global economic crisis, as a consequence of the COVID-19 pandemic, has put the drive for efficiency into top gear,” Philipp Nellessen, CEO of thyssenkrupp Industrial Solutions Sub Sahara Africa, said. “Fundamental to this drive is cutting-edge technology. Through our ongoing investment in people and R&D and our over 200 years of expertise, we are able to develop advanced technologies to assist mining and other industries in achieving maximum operational efficiencies.”

Although the South Africa mining industry was not operational during national lockdown Level 5, critical repairs were still permitted. As an essential service provider, thyssenkrupp has been delivering maintenance and repair as well as rebuild work to local mines.

The company assisted a platinum mine in Limpopo Province with a roll change on one of thyssenkrupp’s flagship products, a high pressure grinding roll (HPGR).

Nico Erasmus, thyssenkrupp Industrial Solutions Sub Sahara Africa Head of Service Operations, explained: “The scope of work required a rebuild on the HPGR set as well as the installation of the hardware on the mine site, making this our largest project in the national lockdown period.

“We are very pleased that even in a complete lockdown situation, we were able to complete the project in a healthy and safe manner, in excellent co-operation with our customer.”

The customer had “excellent controls” in place and thyssenkrupp complemented the risk mitigation with its own additional preventative protocols, he added.

Procedures included pre-selection of a team that falls inside the recommended age and health categories, pre-screening at both thyssenkrupp and customer sites, limiting the amount of people on shifts and in spaces, adhering to stringent hygiene measures (hand sanitising, wearing face masks, social distancing, cleaning of surfaces, tools and equipment), and implementing special transport and accommodation measures.

According to Erasmus, despite several challenges, the team adapted quickly to all the controls while still being responsive enough to get the work done safely and within the scheduled timelines.

“The transport of super loads (two trucks with 120 t loads each) was a real challenge, but our logistics team rose to the occasion and got the loads on site in no time and ready for installation,” Erasmus said.

To remain operational and continue seamless service delivery to customers, thyssenkrupp has implemented all necessary policies in line with South Africa Government COVID-19 regulations.

These include possession of all essential services permits and strict entry control protocols for employees, visitors and suppliers at all premises. Employees are required to attend mandatory training sessions conducted by the OSH department, wear all necessary personal protective equipment, sanitise regularly and maintain social distancing.

A dedicated COVID-19 committee has been set up to assess changing regulations and risks associated with office and site working environments, the company said.

“With the majority of employees working from home, we have faced our fair share of challenges but the process was very well organised with IT managing it all incredibly well ensuring that everybody was equipped in time,” Erasmus said. “We only had one day of downtime at our essential service workshop site.”

Wrapping up, an optimistic Nellessen says he is in no doubt that South Africa/Sub-Sahara Africa will recover.

“The people here are incredibly brave and innovative and companies will find their way out of the crisis,” he said.

“Despite tough times ahead for some industries, the mining sector continues to show growth and here I foresee a restart and a good recovery, depending on mining commodities probably taking anything between three to 12 months to reach previous and required pricing levels.”

Weir Minerals gives its skew view on HPGRs

With industry demand for high pressure grinding rolls (HPGR) on the up, Weir Minerals is arguing that skewing is a vital feature for modern HPGRs to reduce wear, save downstream energy and ensure optimal grinding across the whole feed.

The company was sharing its findings following the publication of a new white paper.

Weir said: “With their excellent throughput capacity, low maintenance requirements and energy efficiency, HPGRs are fast becoming a go-to for greenfield projects looking to maintain their margins despite commodity price pressures and declining ore grades.”

The mineral processing company said, in the June quarter, that it had registered strong demand for its Enduron® HPGR technology during the three-month period, later on in the year confirming a major order, which included this comminution equipment, from Fortescue Metals Group for its Iron Bridge magnetite project in Western Australia.

Henning Knapp, HPGR Process Team Leader for Weir Minerals, said the applications from this equipment have evolved from the cement production days of the 1980s and are increasingly being deployed as tertiary and quaternary crushers in mineral comminution circuits, dealing with tougher ores including iron, gold, copper and diamonds.

“As any engineer will tell you, it’s almost impossible to eliminate feed variance and segregation completely. In the past, this has posed a critical challenge for HPGR operators – but dynamic skewing such as that featured in the Enduron HPGR, maintains optimal pressure across the entire feed.”

Traditionally, HPGR manufacturers have shied away from skewing designs, for fear of roller misalignment creating unfavourable load distributions, and preventing the use of flanged guards to reduce the edge effect, the company said. “However, Weir Minerals’ unique roller bearings design allows for skewing alongside effective edge guards, reducing wear and promoting better grinding.”

The downside of static rollers

A HPGR reduces particles by compressing and crushing the feed between two equally sized, parallel rollers rotating in opposite directions, with a small gap between them. This compresses the feed to 80% of its solid density, where the force of the rollers pushes the rocks against each other and exceeds their compressive strength.

“Inter-particle comminution avoids the direct component wear caused by conventional comminution techniques, and applies immense pressure, up to 27,000 kN, across the entire particle size distribution, which creates the higher proportion of fines HPGRs are renowned for,” says Knapp.

However, segregated feeds can result in markedly uneven particle sizes across the width of the feed, creating high, abrasive pressure on one side of the roll and insufficient pressure on the other. It will also produce a coarser product, requiring more work downstream, according to Weir.

“To compensate for the edge effect, a lateral wall or ‘cheek plate’ is deployed on either side to prevent material exiting the gap between the rollers sideways. The closer this is to the rollers, the better – but that has prevented engineers from introducing the flexibility needed to cope with feed segregation,” explains Knapp.

How Enduron HPGRs skew to maintain optimum pressure

To accommodate this uneven pressure Enduron HPGRs use a spring-loaded lateral wall which not only reduces the edge effect (maintaining a gap of as little as 1 mm) but is specifically designed to facilitate roll skew.

As shown above, an uneven feed will lead to high pressure on one side and not enough on the other. Having one roller skew will facilitate larger material at one end while ensuring the smaller particles on the other side receive enough pressure to be ground down: it maintains an even pressure distribution across the entire feed, saving energy and reducing wear, Weir says.

“The degree to which the Enduron HPGRs skew is largely dependent on the width of the roll, with longer rolls skewing about 5 mm for every metre the roll is wide. However, the effect of even small changes can be significant on local pressure peaks,” says Knapp.

“The skewing should be managed by an advanced control system, which steers the rolls to satisfy the desired output pressure. This system also ensures the skew isn’t too great or maintained for too long, which both disrupt the compressive bed.”

In the case of prolonged or excessive skewing, Enduron HPGRs send a signal notifying the supervising control system and operating staff. Prolonged skewing generally is indicative of a disturbance or fault in up-stream facilities, such as low bunker filling, upstream crusher wear, screen deck wear, or conveyor failure, Weir says.

“Where static rolls suffer from differential pressure, creating undesired product, consuming more energy and suffering additional wear, Enduron HPGRs maintain optimum pressure across the entire feed thanks to their skewing, spring-loaded lateral walls,” Weir said.

Knapp concluded: “When dealing with competent mineral feeds in real-world conditions, there’s simply no substitute for the Enduron HPGR’s ability to maximise performance with skewing.”