Tag Archives: SAG mill

Orion settles on SAG milling and water treatment at Prieska Cu-Zn project

Two significant engineering changes have had a positive impact on the expected returns from Orion Minerals’ Prieska copper-zinc project in the Northern Cape Province of South Africa.

Issuing an updated bankable feasibility study (BFS) for a proposed new 2.4 Mt/y copper and zinc mining operation earlier this week, the company said there had been “numerous improvements” on the previous study completed in June 2019.

This included a 43% increase in post-tax undiscounted free cash flows from the project to A$1.2 billion ($798 million); a 36% increase in after-tax net present value (8% discount rate) to A$552 million; and a five-month reduction in the capital payback period to 2.4 years.

In the plant, the major changes include the use of SAG milling, and removal of secondary crushing, screening and rock conveyors.

The use of a SAG and ball milling circuit followed by differential flotation removes the need for multiple stages of crushing – which was included in the previous study.

The new plan envisages a high steel charged SAG mill operating in an open circuit with a secondary ball mill operated in a closed circuit with a classification cyclone cluster. The SAG mill trommel screen oversize feeds a pebble crushing circuit which returns crushed product to the SAG mill feed conveyor, the company said.

The milling circuit, meanwhile, is fed with (F100) 250 mm primary crushed material from the primary stockpile at a throughput rate of 300 t/h and produces a product size of 70% passing 75 μm, which is fed to the differential flotation circuit.

In a presentation, Orion stated that the processing plant costs from the 2019 study to the latest BFS had dropped 16% to A$91 million.

The next big change was a different de-watering philosophy of the old workings of Prieska, with the BFS including a new water treatment route. This resulted in a 30% decrease in the shaft dewatering timeline, it said.

The Hutchings Shaft and underground workings at Prieska are currently filled with water to a depth of 310 m below surface and contain a volume of 8.6 Mcu.m of water.

Dewatering of the workings via a pumping system to be installed in the Hutchings Shaft is now planned, with water being pumped into a 1 Mcu.m volume dewatering dam on surface, from where mechanical evaporators and a reverse osmosis water treatment plant will be used to dispose of and treat the water for discharge into the environment.

The use of water treatment supplements mechanical evaporation, which allows the pumping schedule to be accelerated by four months, Orion said. “Furthermore, the Department of Human Settlements, Water and Sanitation stipulated as part of the IWUL (Repli Integrated Water Use Licence) application process that provision be made for a portion of the dewatered volume to be made available for social, commercial or agricultural use in the locality.”

Forced evaporation is planned to be used as the primary means to dispose of the water with the water treatment plant (WTP) as the secondary means to treat and then discharge treated water into the environment as irrigation water.

Forced evaporation requires the use of a large evaporation dam, according to Orion, which impacts environmental considerations when compared with the small footprint required by the WTP.

“This is mitigated through the early construction of the tailings storage facility (TSF) which serves a dual purpose for early project phase dewatering and later as a TSF during the operational life of the mine,” the company said.

These actions, in addition to prioritising the extraction of higher grade (and confidence) mineral resources earlier in the mine schedule, helped significantly improve the project return economics, according to Orion.

While the changes also came with a 9% increase in peak funding requirements to A$413 million to cater for the operational improvements, it would also see 20% more payable copper produced – 226,000 t – and 17% more payable zinc produced – 680,000 t – over the 12-year mine life.

Orion’s Managing Director and CEO, Errol Smart, said: “With the Prieska BFS update now complete, the development of the Prieska project is ideally positioned to play a vital role in the local economic recovery plan for the Northern Cape region.

“The project’s low exposure to imported materials and foreign labour reduces construction challenges as the world overcomes and recovers from COVID-19.”

Smart added that the company was targeting a production start-up in 2024 as market conditions permitted.

Zest WEG keeps DRC mining project on track in face of COVID-19 restrictions

The Zest WEG Group, a subsidiary of leading Brazilian motor and controls manufacturer WEG, is intent on keeping its customers’ projects on track despite COVID-19-related travel restrictions and has devised a way to complete the final step in the manufacturing process remotely.

In an innovative first to keep a customer’s mining project in the Democratic Republic of the Congo on schedule, Zest WEG successfully conducted a remote witness test of medium voltage (MV) variable speed drives (VSDs) in WEG’s Brazil factory.

David Spohr, Business Development Executive for high-voltage equipment at South Africa-based Zest WEG, said these extraordinary times called for extraordinary measures.

“With the restrictions on international travel, we had to think creatively about how to complete this final step in the manufacturing process – the witnessed factory acceptance test (FAT) – before the equipment could be shipped to the DRC site,” he said.

Under normal circumstances, these tests would require the customer to travel to Brazil and spend a week at the factory witnessing and signing off a range of detailed test and equipment requirements.

This order comprised two 7 MW, 3,300 V WEG MVW01 VSDs for the ball and SAG mill drive application and two 1.2 MW, 3,300 V WEG MVW01 VSDs for the high pressure grinding roll (HPGR) mill application. Both applications required non-standard features, according to the company, namely “frozen charge protection” software on the ball and SAG mill application and a “master and follower” configuration on the HPGR mill application, it said.

Spohr said: “It was essential that we did not delay the customer’s project, so we arranged to conduct the witness test using web-based communication software. This allowed the participation of Zest WEG experts, the engineering contractor and the end user, all from the safety of their homes in Johannesburg – communicating with five testing technicians in the WEG factory in Brazil.”

Using a high-definition camera and web-based communication software, the factory technicians were able to walk the contractor and end user through each element of the FAT, with clear and real-time visual images of the test results and equipment on the factory floor, according to the company.

The tests continued for three days, beginning at 13:00 and ending at 19:00 to account for time zone differences. Testing covered three key areas – PLC communication software integration, full functional testing and full load testing, according to the company.

“As with any other witnessed FAT, the customer was provided with a comprehensive results report by WEG,” Spohr said. “This enabled the customer to check, in exactly the same way, that the remote FAT results were within the required tolerances.”

Spohr noted that this pioneering step is likely to influence the way these tests are done in future.
“It has shown that the testing can be done to the same standards, but with significant savings in time and cost,” he said.

Metso wins major mill lining order from Russian Copper Company

Metso is to supply SAG and ball mill linings for the facilities of Russian Copper Company’s (RCC) in-development Tominsky processing plant (TPP), in Russia.

The TPP is RCC’s biggest investment project and one of the largest scale and high-tech projects commissioned in Russia in recent years, according to RCC. The plant will be constructed at the Tominsky copper porphyry deposit and will have a capacity of 28 Mt/y of copper ore, producing up to 500,000 t/y of copper concentrate, the company said.

The Metso contract complements two earlier mill lining contracts for RCC’s Mikheevsky processing plant, signed in December 2019, the mining OEM said.

With a combined value of approximately €24 million ($26.1 million), the three orders have been booked for Metso’s March quarter 2020 (Tominsky) and December quarter 2019 (Mikheevsky) orders received, it said.

First shipments started already in March, with the RCC deliveries covering almost one year’s worth of mill lining needs, according to the company.

Alexey Muzychkin, Metso Senior Vice President in Russia and CIS, said: “We are proud to be part of the construction projects of RCC by providing reliable supplies of equipment and spare parts for their plants. We managed to meet the tight delivery schedule required to ensure the smooth operation of RCC’s production facilities.”

Vsevolod Levin, President of RCC, said: “RCC implements the best available technologies at its operations, as well as installs equipment from the world’s leading manufacturers. For this reason, Metso is our long-time reliable partner in implementing the most ambitious projects. This ensures superior operational performance of our enterprises, as well as the safety of technological processes for human health and environment.”

RCC was founded in 2004 and is now one of the biggest copper producers in Russia, according to Metso.

It is a vertically integrated holding company with operational assets in Chelyabinsk, Sverdlovsk, Orenburg, Novgorod, Khabarovsk (all in Russia) and Kazakhstan. RCC manages eight mining enterprises, a hydrometallurgical plant, three metallurgical plants, and a trading company. Together, they cover the complete production cycle, from mining and processing to production and sales.

The company produces copper concentrate, copper cathodes and copper rods, as well as zinc concentrate, refined gold, and refined silver, with its production facilities able to produce 220,000 t/y of copper cathodes and 235,000 t/y of copper rods, Metso said.

JKMRC researchers tackle SAG mill fill productivity challenge with new ‘soft sensor’

Researchers from the Sustainable Minerals Institute’s Julius Kruttschnitt Mineral Research Centre (JKMRC) say they are developing a soft sensor to overcome previously-accepted performance challenges facing SAG mills.

SAG mills are a key asset for mineral processing operations as one of the critical stages of extracting mineral out of ore, and their continued stable operation is central to productivity, the JKMRC says.

However, the performance of a SAG mill changes rapidly in response to conditions such as feed size and hardness, as well as longer-term variability due to liner wear – something no instrumentation can directly observe, according to the research centre.

The new Mill Filling Prediction (MFP) tool is a soft sensor (a mathematical model that act as a sensor) to provide information about the mill’s contents and enable it to be controlled closer to its maximum capacity, it says. The MFP tool is developed by Dr Marko Hilden (pictured with Mohsen Yahyaei here), a Senior Researcher at JKMRC, who transformed and updated models that have been developed by various researchers at JKMRC and developed new models to suit the new application.

Associate Professor, Mohsen Yahyaei, who is JKMRC’s Advanced Process Prediction and Control (APPCo) Group Leader, said the MFP tool includes mathematical models that predict the wear condition of the mill, the level of mill filling, the filling of the steel grinding media and particle trajectory.

“The models capture data from commonly installed sensors around SAG mills, which allows the model to run in real time, giving the operator instant feedback on the critical conditions that affect mill performance,” he said.

“The MFPT is already being implemented at a number of industrial sites, and they are starting to see multiple benefits in the control of the grinding circuit.”

In the mining sector, most energy is used during mineral processing, with comminution – which includes grinding – accounting for 70% of total energy usage in some sub-sectors, according to the JKMRC.

Associate Professor Yahyaei said precisely predicting mill filling can increase operators’ confidence in running the mill at a higher average filling and power draw, thereby increasing overall equipment effectiveness and throughput.

“The operator can be alerted when undesirable conditions such as slurry pooling are imminent, reducing the risk of the mill being overloaded,” he said.

“Estimation and display of steel ball level reduces the need to perform regular manual measurements which require stopping and sometimes entering the mill, and, therefore, reduces the impact on production and personnel health and safety.

“And warnings, when shell impacts are likely, can help the operators select operating conditions that avoid excessive liner wear and grinding media consumption.”

JKMRC’s APPCo Group aims to transform unit process modelling and simulation by moving from steady-state models to techniques that make greater use of data generated on-site and sensor technologies in combination with advanced process control, computational analytics and modelling techniques, according to the JKMRC.

Metso to help Pavlik Gold double processing capacity

Metso says Pavlik Gold JSC has chosen it as the supplier for the key crushing and grinding equipment for its ore processing plant in Magadan, Russia.

The Pavlik gold plant, which commenced its operations in 2015, currently produces around 225,000 oz/y of gold. With the new equipment, the plant expects to double its ore processing capacity and increase gold production, according to Metso.

Metso’s delivery consists of the primary crushing station with a Nordberg® C160™ jaw crusher, one SAG mill and two ball mills with a total installed power of more than 20 MW. The circa-€25 million ($27 million) order has been booked in Metso’s March quarter orders received, with delivery expected to take place in the first half of 2021.

Alexey Muzychkin, SVP, Russia and CIS, Metso, said: “We greatly value our long-term cooperation with Pavlik Gold, where Metso’s equipment has been in use already for several years. We are sure that the experience and technical competence of both companies in this type of projects will help us rapidly achieve the goals.”

Earlier this month, FLSmidth announced that it would supply a new 7 Mt/y gold processing plant to the mine. 

Marks reveals Resolution copper concentrator details at SME

There’s some good news for mineral processing equipment suppliers looking to win business from the Resolution copper mine in Arizona, USA: the Rio Tinto/BHP-owned project already has a preliminary concentrator plan in place.

The sticking point is that, according to Anita Marks, Principal Advisor, Process Engineering, Resolution Copper, the plant ground-breaking is not likely for another eight years!

Speaking at the 2020 SME MineXchange Conference & Expo, in Phoenix, Arizona, on Tuesday, Marks revealed the plans for the concentrator at the mine, which when operational could become the largest copper producer in North America.

The project, situated close to the former-operating Magma mine, is currently in the process of deepening Shaft 9 down to a level of 2,086 m deep. The project partners will have spent over $2 billion (Rio Tinto share $1.1 billion) by the end of this year to develop and permit the project, including $302 million of additional expenditure approved earlier in 2019. Marks’ long timeline to groundbreaking is a reflection of the lengthy permitting process the project will have to go through.

Following the shaft deepening – expected to be completed in 2021 – and if the project receives the required approvals, development work for the block cave mine could start to take place.

At the same time as the company is focused on these aspects of the project, Resolution is leveraging the drill core it has obtained to calculate all-important metallurgical information and come up with a preliminary concentrator design.

The project has delineated indicated and inferred resources totalling 1.97 Bt at 1.53% Cu and 0.036% Mo from drilling, so there are many datapoints to draw from when it comes to generating a process flowsheet. It has used 79,000 ft (24,079 m) of core – including 38 full holes and 10 partial holes – 527 grindability samples, 646 rougher/cleaner kinetic tests and three pilot projects to come up with these plans, according to Marks.

Ahead of the concentrator, ore will be crushed underground – possibly with a gyratory crusher – and conveyed underground before being hoisted to surface.

The concentrator looks like having a SAG and ball mill configuration without a pebble mill (at least in the initial stages), plus a large cell bulk flotation circuit with columns for cleaning. It would have a separate float for tailings separation and produce both a copper and molybdenum concentrate.

This has the potential block cave mine producing 120,000 t/d of ore, with plant availability expected to be 92%.

And water consumption and recycling are high on the priority list for the project, with Marks saying the company is trying to reclaim as much water as possible. A tailings thickener is expected at the concentrator itself, with the aim to capture 80-85% of the water used in the process, she said.

Outotec mineral process equipment destined for Okvau gold project

Outotec says it has been awarded a contract from Renaissance Minerals, a subsidiary of Emerald Resources, for the delivery of process equipment to the greenfield Okvau gold project, in Cambodia.

The order value, booked into Outotec’s 2020 March quarter order intake, is around €13 million ($14.2 million).

Outotec’s scope includes the delivery of an Outotec HIGmill® high intensity grinding mill, a semi-autogenous (SAG) mill, TankCell® flotation cells, an OKTOP® Conditioner, thickeners and spare parts.

The Okvau gold project is in the Mondulkiri province of eastern Cambodia. The 2 Mt/y operation will be the first large-scale mining project in the country, according to Outotec, with project commissioning expected in the June quarter of 2021.

Last year, ASX-listed mining contractor, MACA, entered into a memorandum of understanding with a subsidiary of Emerald Resources to supply equipment and contract mining services at the project.

Paul Sohlberg, Head of Outotec’s Minerals Processing business, said: “We are pleased to be part of Cambodia’s first significant gold processing project with Emerald’s highly credentialed gold project development team.

“Outotec’s leading technologies such as energy efficient ultrafine grinding, proven flotation technology for low grade sulphide ore and superior thickening technology, enable our customer to do profitable business sustainably. This order will strengthen Outotec’s position as a supplier of advanced minerals processing technologies in Southeast Asia.”

FLSmidth to help modernise crushing, grinding circuit at Zijin’s Serbia copper op

Zijin Mining Group has chosen an FLSmidth gyratory crusher, SAG mill and ball mill for the Majdanpek mine, part of the Chinese mining company’s majority owned Zijin Bor copper mine, in Serbia.

The delivery of the equipment to Majdanpek, 180 km from Belgrade, is expected to occur between 12 and 18 months from now, with the project estimated to reach completion by the end of 2020. The order has a combined value of around DKK200 million ($30 million), according to FLSmidth, and has been recognised in the order intake for the September quarter.

The order of the new FLSmidth crushing and grinding circuit for the front end of the concentrator comes as Zijin looks to modernise Majdanpek, which will be the largest of its three Serbian copper concentrators, FLSmidth said.

Acquired as part of the majority acquisition of Bor in late 2018, the Majdanpek mine uses open-pit mining and flotation to produce copper concentrates, with a designed mining and processing scale of 10 Mt/y, according to Zijin. The operation is currently at a scale of 6 Mt/y, it said.

In the next six years, the company says it plans to invest more than $1 billion in the upgrading, expansion, or construction of the four mines and smelter at Bor. After the completion of the first phase of the project, it is estimated output will go to 82,000 t/y of copper in concentrates, with the smelter producing 80,000 t/y of copper cathode. After the completion of phase two, this could go to 120,000 t/y of concentrate and 150,000 t/y of cathode.

Manfred Schaffer, President of Mining and Group Executive Vice President at FLSmidth, said: “This extensive order underlines the strong value proposition of FLSmidth to our customers in the copper industry. Our market leading crushers and mills will provide significant improvements for Zijin Mining in terms of productivity and processing efficiency.”

Flotation and grinding circuit classification rise to the top in CEEC awards

The Coalition for Energy Efficient Comminution (CEEC) has announced the recipients of its 2019 CEEC Medals, which are granted annually to authors of outstanding papers presenting “innovative approaches to enhancing energy efficiency in comminution and mineral processing”.

Dr Zeljka Pokrajcic, CEEC Medal Evaluation Committee Chair, announced that the CEEC Medal for Technical Research was awarded to Laureate Professor, Graeme Jameson AO, and Dr Cagri Emer from the Centre for Multiphase Processes, University of Newcastle, New South Wales, Australia, for their publication, ‘Coarse chalcopyrite recovery in a universal froth flotation machine.

The CEEC Medal for Operations was awarded to Kyle Bartholomew, Rob McIvor and Omar Arafat from Metcom Technologies, Grand Rapids, Minnesota, USA, for their publication, ‘A guide to maximising ball mill circuit classification system efficiency (CSE), for operators and equipment designers.’

Dr Pokrajcic said: “The Evaluation Committee closely considered a number of high quality nominations from leading global industry experts before shortlisting two research papers and three operations papers.”

Jameson and Emer’s (pictured) CEEC Medal winning paper was published in Minerals Engineering (134, 118-133) in January and documents a flotation device, the NovaCell. The NovaCell features a fluidised bed for coarse particle collection and a high shear aeration zone for ultra-fines separation, CEEC said. The researchers’ case study showed the device resulted in a 40% reduction in comminution energy and a 12% reduction in overall site operating cost.

Dr Pokrajcic said the entry was a clear standout in the Technical Research category, presenting high quality research that was well supported by strong technical information and cost analysis.

“The paper presents a new dual-zone flotation device for both coarse and fine particle separation. It reinforces important developments that are supporting industry’s move to coarse particle flotation at scale,” Dr Pokrajcic said.

“This work shows leadership in flotation approaches that can significantly improve comminution efficiency and productivity. It also provides a compelling case for the reduction of operating and capital costs by removing coarse size waste in the comminution circuit.”

The winning Operations Medal paper by Bartholomew, McIvor and Arafat was presented at the 14th AusIMM Mill Operators’ Conference, in Brisbane, in August 2018.

Dr Pokrajcic said the paper provided a “useful methodology for measuring and improving classification efficiency in a grinding circuit”, highlighting the importance of classification in comminution circuits to improve efficiency and productivity.

The paper’s case study measured an almost 25% increase in the generation of new -25 micron material following an increase in ball mill re-circulating load and optimising cyclone performance, according to CEEC.

“The three authors from Metcom Technologies are highly regarded contributors to the field of comminution efficiency, last year publishing (along with Jim Finch) a paper on ball mill classification system optimisation that was Highly Commended by the CEEC Medal judges,” CEEC said.

Dr Pokrajcic said: “This year’s exceptional CEEC Medal winning paper by Bartholomew, McIvor and Arafat provides a succinct, clear, systematic approach to practical operational improvements that not only helps inform operations of the efficiencies that can be achieved, but also demonstrates the economic case for change.”

The 2019 CEEC Medal Evaluation Committee also selected three papers for High Commendation. The recipient in the Technical Research category was Hamid Manouchehri for his paper, ‘How Far the Crushing Performance Can be Pushed? Cone Crusher vs Vertical Shaft Impactor (VSI)’. This paper was presented at Comminution ‘18, in Cape Town, South Africa.

CEEC said: “Manouchehri’s paper presented an adept comparison of the conventional cone crusher and the VSI in a fine crushing duty, and third and fourth stage crushing duty.”

The judges added: “His trials conducted at pilot scale and at laboratory showed the VSI produced more fines, and in some cases product of higher porosity, reducing downstream power consumption.”

In the Operations category, Malcolm Powell, Sarma Kanchibotla, Vladimir Jokovic, Marko Hilden, Benjamin Bonfils, Anand Musunuri, Pamela Moyo, Sam Yu, Jace Young, Paul Yaroshak, Emrah Yalcin and Barun Gorain were awarded High Commendation for their paper, ‘Advanced mine to mill application at the Barrick Cortez Mine.’ This paper was presented at the 14th AusIMM Mill Operators’ Conference.

The CEEC Medal Evaluation judges commented that this was an “outstanding paper” building on the commonly applied mine-to-mill optimisation where grade deportment and dilution, as well as blast movement during high intensity blasting, is considered and evaluated.

Also winning a High Commendation in this category was Berge Simonian for a paper titled, ‘Mount Milligan Mine Performance Update.’ Presented in January at the 51st Annual Canadian Mineral Processors Operators Conference in Alberta, Canada, CEEC said the paper detailed the optimisation and debottlenecking of a relatively new mineral processing circuit.

“Efficiency gains achieved through modification to secondary crushing screening, SAG mill lifter design and ball mill charge optimisation enabled the circuit to operate at throughput beyond design,” the judges said.

CEEC CEO, Alison Keogh, praised the CEEC Medal recipients and Highly Commended authors, saying their outstanding contributions help inspire and foster industry uptake of eco-efficient comminution and processing.

Keogh said: “The CEEC Board thanks the successful authors and each of the nominees for their important research efforts and case studies. These publications, shared widely via CEEC’s global network, provide tangible value by helping operators, researchers and METS companies take steps to operate more efficiently while reducing their energy usage, footprint and costs.”

To view the abstracts and to find out more about the CEEC Medal visit www.ceecthefuture.org/ceec-medal

Miners able to pick ‘n’ mix with latest FLSmidth mill lining components

FLSmidth says it has launched redesigned mill lining components engineered to suit the specific functions and differing operating environments of the mining industry with its.

The new PulpMax™ mill liners are designed to increase the throughput of semi-autogenous (SAG) mills and substantially boost the wear life of liners, the company said.

FLSmidth said: “Delivering on a promise to provide increased productivity to the mining industry, the composite design incorporated in FLSmidth’s new PulpMax mill liners ensure that users enjoy reduced downtime and maintenance, increased throughput and improved worker safety.”

With lighter weight mill liners, installation is faster and safer as each liner is easier to manipulate, according to the company. There are also fewer parts, and, hence, fewer movements are required to perform a reline, resulting in a significant decrease in scheduled downtime.

The composite nature of the liner reduces its weight by almost 50%, according to FLSmidth, which allows the plant to increase its ball charge level without increasing the total weight of the mill.

This higher ball charge further contributes to the higher throughput.

“The lighter weight of these liners has an important impact on size, design and installation time,” the company said. “Each liner can now be larger – subject to the size of the mill opening – and the mill can be lined with fewer of them, reducing the downtime required to conduct replacement.

A lighter liner means fewer bolts to hold it in place, a factor further reducing installation time, according to the company. This shorter downtime also means less time for contractors inside the mills, leading to a faster and safer liner changeout.

Another important benefit of the composite material used in many of FLSmidth’s redesigned liners is it is not necessary to torch the liners, as is sometimes required when removing old steel liners, the company said. “This torching process in the mill is best avoided, as it can cause costly damage to the mill shell,” FLSmidth explained.

Finally, there has also been the development of composite material shell liners bolted from the outside of the mill, once again, speeding up installation and reducing risk.

Jack Meegan, Product Line Manager for Comminution at FLSmidth, said: “As mines increasingly recognise the positive financial impact derived from just a few more percentage points in throughput improvement, many are looking beyond conventional steel cast liners for mills. FLSmidth’s innovations, based on combinations of steel, rubber and ceramic components, allow the liners to be thinner, resulting in a larger volume inside the mill, making higher charge levels possible.”

He continued: “Responding to the continuous assessment of customer needs, FLSmidth has launched a mill liner solution based on extensive data on mill operations, shutdowns, wear profiles and other factors. These have been used to develop a high-end technical and financial solution.”

Following installation, an ongoing measurement of actual wear, tonnage processed and estimated wear life is conducted so further recommendations can be made to improve performance, Meegan explained.