Tag Archives: dry stacking

Anglo American Platinum’s modernisation drive to continue into 2021

Anglo American Platinum says it is looking to deliver the next phase of value to its stakeholders after reporting record EBITDA for 2020 in the face of COVID-19-related disruption.

The miner, majority-owned by Anglo American, saw production drop 14% year-on-year in 2020 to 3.8 Moz (on a 100% basis) due to COVID-related stoppages. Despite this, a higher basket price for its platinum group metals saw EBITDA jump 39% to R41.6 billion ($2.8 billion) for the year.

As all its mines are now back to their full operating rates, the company was confident enough to state PGM metal in concentrate production should rise to 4.2-4.6 Moz in 2021.

Part of its pledge to deliver more value to stakeholders was related to turning 100% of its operations into fully modernised and mechanised mines by 2030. At the end of 2020, the company said 88% of its mines could be classified as fully modernised and mechanised.

There were some operational bright spots during 2020 the company flagged.

At Mogalakwena – very much the company’s flagship operation – Anglo Platinum said the South Africa mine continued its journey to deliver best-in-class performance through its P101 program.

Rope-shovel performance improved to 26 Mt in 2020, from 15 Mt in 2019, while drill penetration rates for big rigs increased from 15 m/h, to 16.7 m/h. Alongside this, the company said its Komatsu 930E truck fleet performance improved to 298 t/load in 2020, from 292 t/load in 2019.

These were contributing factors to concentrator recoveries increasing by two percentage points in 2020 over 2019.

During the next few years, the company has big plans to further improve Mogalakwena’s performance.

In 2020, the mine invested R500 million in operating and capital expenditure, which included commissioning a full-scale bulk ore sorting plant, coarse particle rejection project and development of the hydrogen-powered fuel-cell mining haul-truck (otherwise referred to as the FCEV haul truck).

First motion of the 291 t FCEV haul truck is still on track for the second half of 2021, with the company planning to roll out circa-40 such trucks from 2024.

Anglo Platinum said the bulk sorting plant (which includes a Prompt Gamma Neutron Activation Analysis and XRF sensor-based setup, pictured) campaign at the Mogalakwena operation is due to end this quarter.

The company’s hydraulic dry stacking project is only just getting started.

This project, which involves coarse gangue rejection before primary flotation for safer tailings storage facilities, is expected to see a construction start in the June quarter, followed by a campaign commencement and conclusion in the September quarter and December quarters, respectively.

On another of Anglo Platinum’s big technology breakthrough projects – coarse particle rejection for post primary milling rejection of coarse gangue before primary flotation – the company plans to start a campaign in the December quarter of this year and conclude said campaign by the end of the March quarter of 2022.

The company also has eyes on making progress underground at Mogalakwena, with a hard-rock cutting project to “increase stoping productivity and safety” set for Phase A early access works this year. This project is set to involve swarm robotics for autonomous, 24/7 self-learning underground mining, the company said.

Lastly, the company’s said the digital operational planning part of its VOXEL digital platform had gone live at Mogalakwena. VOXEL is expected to eventually connect assets, processes, and people in a new digital thread across the value chain to create a family of digital twins of the entire mining environment, the company says. Development is currently ongoing.

Looking back to 2020 performance at the Unki mine, in Zimbabwe, Anglo reflected on some more technology initiatives related to R26 million of expenditure for a digitalisation program. This included installing underground Wi-Fi infrastructure, as well as a fleet data management system to track analytics on primary production equipment. The company says these digital developments will enhance real-time data analysis, improve short-interval control and overall equipment effectiveness.

To step up mechanisation of its PGM operations at Amandelbult, Anglo American Platinum is also investing in innovation.

This includes in-stope safety technologies such as split panel layouts to allow buffer times between cycles, creating safer continuous operation and reduced employee exposure; improved roof support technology and new drilling technologies; a shift to emulsion blasting from throw blasting; and safety enhancements through fall of ground indicators, 2 t safety nets, LED lights, and winch proximity detection.

Meanwhile, at the company’s Mototolo/Der Brochen operations, it is working on developing the first lined tailings storage facility at Mareesburg in South Africa to ensure zero contamination of ground water. The three-phase approach adopted for construction of this facility will be completed this year.

Ivanplats eyes Platreef project fast track following Shaft 1 sinking work

An integrated development plan (IDP) on the Platreef palladium, platinum, rhodium, nickel, copper and gold project in South Africa has shown the potential to fast-track the development into production.

Consisting of an updated feasibility study and a preliminary economic assessment, the IDP marks an “important step in our vision of building and operating the world’s next great precious metals mine, together with our local community and Japanese partners”, Ivanhoe Mines Co-Chair, Robert Friedland, said.

Ivanhoe indirectly owns 64% of the Platreef project through its subsidiary, Ivanplats. The South Africa beneficiaries of the approved broad-based, black economic empowerment structure have a 26% stake in the project, with the remaining 10% owned by a Japanese consortium of ITOCHU Corporation, Japan Oil, Gas and Metals National Corporation, and Japan Gas Corporation.

The Platreef 2020 feasibility study builds on the results of the 2017 feasibility study and is based on an unchanged mineral reserve of 125 Mt at 4.4 g/t 3PGE+Au, project designs for mining, and plant and infrastructure as in the 2017 study; except with an increased production rate from 4 Mt/y to 4.4 Mt/y, in two modules of 2.2 Mt/y, for annual production of more than 500,000 oz of palladium, platinum, rhodium and gold; plus more than 35 MIb of nickel and copper.

The 2020 feasibility study includes an updated production schedule based on the current project status, costs and economic assumptions, with the schedule for the latest study driven by the sinking of the project’s second, larger shaft (Shaft 2), where early works have commenced. The 2020 study envisions Shaft 2 equipped for hoisting in 2025, allowing for first concentrate production in the latter half of the year. The initial capital cost for the Platreef 2020 feasibility study is estimated at $1.4 billion.

The Platreef IDP also includes the Platreef 2020 preliminary economic assessment, which is an alternate, phased development plan that fast-tracks Platreef into production. The plan uses the project’s first shaft (Shaft 1) for initial hoisting and mine development, with 825,000 t of annual total rock hoisting capacity, of which 125,000 t is allocated for development rock. The alternate plan envisions building an initial concentrator with a capacity of 770,000 t/y, and could produce first concentrate in mid-2024.

“The recently-completed sinking of Shaft 1 has created the opportunity to access early, high-grade tonnes in this scenario,” the company said. “While the 700,000 t/y initial mine is being operated using Shaft 1, there would be opportunities to refine the timing of subsequent phases of expanded production, which is driven by the sinking of Shaft 2.”

Once completed, two 2.2 Mt/y concentrator modules would be commissioned, and the initial concentrator would be ramped up to its full capacity of 770,000 t/y; increasing the steady-state production to 5.2 Mt/y for annual production of more than 600,000 oz of palladium, platinum, rhodium and gold, plus over 40 million pounds of nickel and copper. The initial capital cost for 700,000 t/y under the Platreef 2020 assessment is estimated at $390 million – substantially lower than the Platreef 2020 feasibility study that requires Shaft 2 for first production.

Detailed engineering has commenced on the mine design, 770,000 t/y concentrator and associated infrastructure for the phased development plan, which will be incorporated into an updated feasibility study in 2021, Ivanhoe said. The Shaft 1 changeover will take place simultaneously in preparation for permanent hoisting by early 2022. The budget for 2021 is $59 million, which includes $10 million for commencement of the construction of the headframe to the collar of Shaft 2.

“The Platreef IDP reflects the first phase of development for the Platreef Mine,” the company said. “It is designed to establish an operating platform to support potential future expansions to 12 Mt/y and beyond, as demonstrated in previous studies, which would position Platreef among the largest platinum-group metals producing mines in the world, producing in excess of 1.1 Moz of palladium, platinum, rhodium and gold per year.”

Friedland said: “The thick and flat-lying nature of the high-grade mineralisation of Platreef’s Flatreef deposit will accommodate the use of mechanised and state-of-the-art, automated mining techniques; allowing us to efficiently and safely bring material to surface to produce precious metals vital to a proliferation of modern technologies.”

Marna Cloete, Ivanhoe’s President and CFO, said approximately 60% of the mine’s tailings will be sent back underground to fill mined-out voids, and the remainder will be treated using sustainable, dry-stacking technology.

Mining zones in the current Platreef mine plan occur at depths ranging from around 700-1,200 m below surface. Once expanded mine production is achieved, primary access to the mine will be by way of a 1,104-m-deep, 10-m-diameter production shaft (Shaft 2). Secondary access to the mine will be via the 996-m-deep, 7.25-m-diameter ventilation shaft (Shaft 1) that recently has been sunk to its final depth. During mine production, both shafts also will serve as ventilation intakes. Three additional ventilation exhaust raises (Ventilation Raise 1, 2, and 3) are planned to achieve steady-state production.

Mining methods included in the studies are longhole stoping and drift-and-fill. Each method will use cemented backfill for maximum ore extraction. The production plans in both the PEA’s initial five-year drift-and-fill mining operation off of Shaft 1 and the larger feasibility study expansion are focused on maximising higher-grade areas, which was achieved through optimisation based on stope locations, stope grades, mining method, and zone productivities. The orebody was targeted to recover around 125 Mt at the highest net smelter return.

The ore will be hauled from the stopes to a series of internal ore passes and fed to the bottom of Shaft 2, where it will be crushed and hoisted to surface.

Comminution and flotation test work has indicated that the optimum grind for beneficiation is 80% passing 75 micrometres. Platreef ore is classified as being ‘hard’ to ‘very hard’ and thus not suitable for semi-autogenous grinding; a multi-stage crushing and ball-milling circuit has been selected as the preferred size reduction route, Ivanhoe said.

Improved flotation performance has been achieved in test work using high-chrome grinding media as opposed to carbon steel media. The inclusion of a split-cleaner flotation circuit configuration, in which the fast-floating fraction is treated in a cleaner circuit separate from the medium- and slow-floating fractions, resulted in improved PGE, copper and nickel recoveries and concentrate grades.

A two-phased development approach was used for the flowsheet design comprising a common three-stage crushing circuit, feeding crushed material to milling-flotation modules. Flotation is followed by a common concentrate thickening, concentrate filtration, tailings disposal and tailings-handling facility. The phased approach allows for increased processing flexibility and introduces process redundancy while allowing for phasing of capital and mine ramp-up, the company said.

To further evaluate optimisation opportunities and confirm additional detail design parameters, a mini pilot plant test work program is proposed and will be undertaken as part of the project implementation phase.

The proposed tailings storage facility (TSF) will be developed as a dry stack TSF with an estimated operating life of 32 years. During this time, some 55.4 Mt of tailings will be stored within the dry stack TSF, with the remainder of the tailings to be used as backfill in the underground mine. The dry stack TSF design also caters for an 8 Mt/y ramp-up in production to be explored in future studies.

The dry stack TSF is compliant in terms of required tonnage profile production split between the backfill requirement and dry stack TSF of 35% on average, but is conservatively designed for 40% of non-ore material reporting to the TSF.

Since the Platreef 2017 FS, a hybrid paddock deposition methodology was proposed; however, Ivanplats has decided to change the TSF deposition methodology from upstream design to dry stacking in the Platreef 2020 studies.

Following a study undertaken by Golder Associates Africa in December 2016, it was concluded that stacked tailings storage facilities are deemed to be safer in that there is no hydraulic deposition, hence the risk will be minimal to flood the surrounding areas with tailings in the unlikely event of a catastrophic failure.

“Stacked tailing storage facilities are more water efficient in that the majority of water in the tailings is captured in the dewatering plant, pumped directly back to the concentrator and re-used within the process,” the company said.

The stacked facility will comprise a starter dam constructed primarily of rock fill, engineered tailings, nominally compacted tailings, and random fill. Tailings will be delivered to the dewatering plant situated at the stacking facility using the same pumping systems from the processing plant. Dried tailings will be delivered to the stacking facility using load and haul transportation with trucks from the dewatering plant.

Aside from the rock fill in the starter dam and drainage elements, which include a return water dam, the facility will be developed using dewatered tailings. The infrastructure will have to be in place upon start-up.

For the Platreef 2020 PEA development scenario, it is envisaged to use the approved rock dump footprint within the immediate Platreef mine and concentrator areas, as a dry stacking tailings facility for the initial 700,000 t/y mine. Golder Associates currently is performing the design work to apply for the relevant licences and/or amendments to the existing authorisations.

Los Andes Copper confirms dry stacked tailings plan at Vizcachitas

Los Andes Copper has received results from the ongoing prefeasibility metallurgical study on its Vizcachitas copper project which, consistent with all prior test work conducted, confirms the adoption of dry stacked tailings at the Chile asset.

During 2020, Los Andes has continued metallurgical testing at the SGS laboratory in Santiago, Chile. The test work was carried out on representative samples from locked cycle flotation tailings that reproduce the expected particle size distribution for the coarse and fine tailings fractions at Vizcachitas, it explained.

The planned prefeasibility study (PFS) system for the water recovery is to use vacuum belts for the coarse tailings and pressure filters for the fine tailings. The filtration rates for coarse fraction vacuum filtration are between 1.8-2.0 t/h/sq.m and the fine fraction pressure filtration rates between 0.5-0.6 t/h/sq.m. The expected average filtered cake moisture is between 15-18%, confirming that the Vizcachitas ore is amenable to being filtered and dry stacked.

As the PFS advances, the decision to implement filtered tailings for dry stacking reflects the commitment of Vizcachitas to become one of the early adopters of the environmental friendly technology that will guide global mining in the future, Los Andes said.

Filtration reduces water consumption by 50% when compared with thickened tailings disposal alternatives (60-70% reduction when compared to traditional disposal alternatives), according to the company. Furthermore, filtered tailings can be handled by trucks, conveyors and shovels, as other solid bulk materials, eliminating the need for the construction and operation of a tailings dam.

“The latter is a milestone in operational flexibility and safety standards of particular relevance in a seismic country such as Chile,” the company said.

Fernando Porcile, Executive Chairman, said: “The verification that dry stacked filtered tailings is a viable option for Vizcachitas puts us on the forefront of environmentally responsible practices being adopted for the future of sustainable mining globally.

“Water conservation is high on the agenda for many mining companies, especially in Chile, and therefore the fact that we can reduce our water consumption by approximately 60-70% by using this method is a really positive development.

“This is a proven technology which is now being carried over into Tier One copper projects and I am excited that we will be one of the first, large scale, copper mines to utilise it.”

Vale starts dry iron ore concentration pilot with New Steel technology

Vale has inaugurated its new dry pilot plant for processing iron ore in Minas Gerais, Brazil, as it continues to reduce its use of water in ore and waste processing.

The Brazilian technology, known as FDMS (Fines Dry Magnetic Separation), is unique and has been developed by New Steel – a company Vale acquired in late 2018.

The pilot plant, which cost $3 million, is the first step towards the construction of an industrial plant that will have a production capacity of 1.5 Mt/y. The investment in this project is near $100 million, with the commercial plant start-up scheduled for 2022, as the company announced back in February.

Vale estimates that, in 2024, 1% of all the company’s production will use this technology, whose patent is already recognised in 59 countries.

President of New Steel, Ivan Montenegro, said: “NS-03 is a semi-industrial plant to carry out tests on a pilot scale with different types of ore, allowing the definition of operational parameters for commercial-scale projects.”

Installed at Vale’s Ferrous Technology Center, in Nova Lima, the pilot plant is the second to start operating. Between 2015 and 2017, a unit operated at the Fábrica mine, also in Minas Gerais. The results allowed Vale to see the potential of the FDMS technology, it said, ultimately leading to Vale taking over New Steel.

The new pilot unit will be able to concentrate 30 t/h of ore using dry magnetic separation technology equipped with rare earth magnets.

Vale’s Executive Director of Ferrous, Marcello Spinelli, said New Steel puts the company at the “forefront” of investments in ore processing technology.

“We will continue to seek solutions that increase the safety of our operations,” he added.

With New Steel and its dry process technology, Vale estimates that, in 2024, 70% of production will come from dry or natural moisture processing, without adding water to the process and without using tailings dams. Today, the company produces 60% of iron ore using natural moisture processing.

By 2024, from the production using wet processing (30%), 16% will have filtered and dry-stacked tailings, with only 14% continuing to use the conventional method with wet concentration and tailings disposal in dams or deactivated extraction sites.

This transition will see Vale invest $1.8 billion in filtering and dry stacking in the coming years. The first units to use the technique will be Vargem Grande complex (in Nova Lima), Pico mine (in Itabirito), Cauê and Conceição mines (in Itabira), and Brucutu mine (in São Gonçalo do Rio Abaixo).

New Steel’s technology can deliver a concentrate with iron content up to 68% Fe from poor ore with content up to 40% Fe, depending on its chemical and mineralogical composition, according to Vale. Currently, this concentrate is produced by flotation, which uses water. In flotation, the tailings are usually disposed of in dams, but, with the dry concentration technology developed by New Steel, the tailings will be stacked.

Vale is studying methods to use these filtered cakes as raw materials for the civil construction industry, in addition to other initiatives, such as co-products.

Los Andes Copper engineers a Vizcachitas alternative

It is a combination of improved technology, reduced fine grind requirements and maintenance benefits that led to Los Andes Copper replacing the SAG and ball mill crushing circuit proposed in its Vizcachitas copper-molybdenum project preliminary economic assessment (PEA), with a three-stage crushing circuit that uses high pressure grinding roll (HPGR) technology in the tertiary crushing stage, according to Executive Chairman, Fernando Porcile.

In the middle of a prefeasibility study on the Vizcachitas project, Los Andes recently issued an update on the study progress.

A delay of PFS publication to the March quarter of 2021 due to the onset of COVID-19 impacting some of the metallurgical test work and field work at the project might have been the key takeaway for investors, but those in the mining technology game will be focusing on the revised process flowsheet being put forward at the Chile project.

One of the big changes was seen at the front end on the comminution side.

In the close to year since issuing the June 2019 PEA, and with the arrival of Porcile and his team, the company’s understanding of its orebody characteristics and the technology available to it as a new greenfield project owner has grown.

Porcile said the ore at Vizcachitas is very suitable to this energy efficient HPGR technology, with metallurgical test work showing an HPGR circuit can reduce the sensitivity to changes in hardness, providing a product that is more consistent in size. This will help reduce major process fluctuations downstream – where there have also been some changes.

The P80 target grind size of 240 microns hasn’t changed much – moving up to a P80 of 240-300 microns – but the SAG and ball mill circuit has been replaced with a three stage crushing circuit using secondary crushers in open circuit and HPGR as a tertiary crusher in closed circuit.

On the preliminary comminution process flowsheet, this includes the use of a Metso Superior™ MKIII primary gyratory crusher, feeding three Nordberg® MP2500™ cone crushers, which move into 40,000 t crushed ore bins. This material is then conveyed to two Metso HRC™ 2600 HPGRs.

Los Andes says the configuration of secondary cone crushers in an open circuit avoids the use of a coarse ore stockpile and recirculation conveyor belts – reducing dust emission sources – while the closed reverse grinding circuit allows less production of fines, which is helpful for the follow-on thickening and filtration stages.

On top of this, the secondary crushing and grinding plant in this setup is close to the primary crusher, which also reduces coarse ore conveying costs.

Porcile said HPGR technology has moved on a long way in the last decade and now represents a more reliable proposition than using the SAG and ball mill circuit previously proposed.

“There is much less risk associated with using HPGRs in a new operation,” he told IM. “Large SAG mills not only take up lots of space within the plant, they can also come with teething problems during start up.”

He added: “HPGRs used to come with lots of wear problems, meaning you had to replace the rollers often. The maintenance on them is that much better now; the rollers do not wear out as quickly and, when they do, you can easily replace them.”

On top of the obvious benefits in energy consumption that come with using HPGR technology, there are positives that can be felt further down the process flowsheet.

“We are very confident that HPGR is the best alternative for our project due to the nature and quality of our ore,” Porcile said. “We produce very little fines, which has an impact on the way we deal with tailings.”

The combination of a lack of fines and low presence of clays (mainly kaolinite) has helped filtration performance in test work, indicating that a dry-stacked tailings solution may be viable at Vizcachitas, Porcile said.

This could provide an up to 50% reduction in water consumption compared with the PEA at Vizcachitas. It could also see some 82% of water recovered throughout the process, in addition to a significant reduction in infrastructure requirements.

“We go from having infrastructure in two valleys in the PEA to one in the PFS,” Porcile said on the latter point.

One may think creating a dry-stacking operation at a 110,000 t/d throughput mine would prove costly and difficult, but the lack of fines and low presence of clays already mentioned means the process is a lot simpler to other dry-stacking projects currently on the table across the globe, according to Los Andes.

Test work to date has indicated that coarse material from the plant (plus-400 microns) could produce a cake with 14%-18% moisture through the use of belt conveyors. This material currently makes up 87% of the envisaged tonnage.

Only 13% of tonnage classed as fines (less than 400 microns) would have to go through pressure filters to produce a 16-19% moisture cake, according to the company.

Porcile says these belt filters work just as well as pressure filters on the coarse material from Vizcachitas but are that much more cost effective.

“Belt filters come with high filtration rates, are low cost (in terms of capex) and are reliable,” Porcile said. “In the study, we envisage saving pressure filters only for the very top level of material.”

While it is too early to talk about the impact these changes will have on the capital expenditure and net present value numbers to be included in the PFS, expect the $1.87 billion and $1.8 billion (after tax and with an 8% discount), respectively, to change.

Vale evaluating wet tailings processing alternatives at Brucutu iron ore mine

Vale says it is evaluating short-term alternatives to the wet processing of tailings at its Brucutu iron ore mine, in Brazil, as it looks to step up processing activities at the Minas Gerais operation.

The Brucutu plant, which used to dispose of tailings in the Norte/Laranjeiras dam – that has been at “emergency level 1” since December 2, 2019 – is continuing to operate at around 40% of its capacity through wet processing and tailings filtration, Vale noted.

Yet, the miner said it was evaluating “short-term alternatives” for tailings disposal, such as the optimised use of the Sul dam. These options are being tested by geotechnical and operational teams and may increase Brucutu plant’s processing capacity to 80%, Vale noted.

It warned that, if such alternatives for tailings disposal or the reclassification of the emergency level for Norte/Laranjeiras dam are not achieved until the end of the June quarter, there will “likely be an impact on the 2020 annual iron ore fines production volume”.

Vale took the decision to temporarily suspend the disposal of tailings at the Laranjeiras dam, part of the Brucutu iron ore mine, while assessing the dam’s geotechnical characteristics, back in December. During the shutdown, the dam will have the Level 1 emergency protocol adopted, Vale said. At that point, Vale put the suspension period at one-to-two months.

At the same time, the company reiterated its plans to continue to invest in dry stacking technologies to reduce its exposure to wet tailings dams.

Vale to build New Steel plant and boost dry iron ore processing aims

Vale says it plans to invest up to $100 million to build an industrial plant for dry magnetic concentration of low-grade iron ore, bolstering its efforts to eradicate wet tailings facilities at its mines.

The technology, known as FDMS (fines dry magnetic separation), is unique, Vale says, and has been developed by New Steel – a company it acquired in late 2018.

The capacity of the plant, which is expected to be installed in Minas Gerais, will be 1.5 Mt/y, with the project due to start up by 2022. Vale estimates that, in 2024, 1% of all the company’s production will use this technology, whose patent is already recognised in 59 countries.

With New Steel, Vale estimates that, in 2024, 70% of production will come from dry or natural moisture processing, without adding water to the process and without using tailings dams. Today, the company produces 60% of its iron ore using natural moisture processing. Of the remaining 30% of production using wet processing, 16% will have filtered and dry-stacked tailings, it said.

By this point, only 14% will continue using the conventional method, with wet concentration and tailings disposal in dams or deactivated extraction sites, compared with 40% of current production. The investment is all part of Vale’s $1.8 billion filtering and dry stacking plan, which it laid out in 2019.

The first units to use the FDMS technique will be the Vargem Grande complex (in Nova Lima), Pico, Cauê and Conceição mines (in Itabira), and Brucutu mine (in São Gonçalo do Rio Abaixo).
According to the President of New Steel, Ivan Montenegro, a pilot plant for FDMS will start operating at the Ferrous Metals Technology Center (CTF, Centro de Tecnologia de Ferrosos), in Nova Lima (Minas Gerais) in the June quarter, with the investment amounting to almost $3 million. The unit will be able to concentrate 30 t/h of dry ore, using magnetic separation technology with rare earth magnets.

“Through this process, New Steel can deliver a concentrate with iron content up to 68%, from poor ore with content up to 40%, depending on its chemical and mineralogical composition,” Vale said. “Currently, this concentration is produced by the method known as flotation, which uses water. In flotation, the tailings are usually disposed of in dams. With the dry concentration technology developed by New Steel, the tailings will be stacked.”

Vale said it is already studying methods to use these dry stack tailings as an input for the civil construction industry, in addition to other initiatives, such as co-products.

The pilot project at CTF is the second carried out by Vale. Between 2015 and 2017, a similar plant was successfully operated at Fábrica mine, in Minas Gerais, it said. These results were essential for Vale to see the potential of FDMS, according to Montenegro. “The technology, however, has been tested since 2013. At the time, the equipment allowed a concentration of 5 t/h, rising to 15 t/h in 2015 and up to 30 t/h in 2017,” it said.

To be aligned with Vale’s future projects, the company is working on the development of large-capacity magnetic separators of up to 100 t/h.

According to Technical Director of New Steel, Mauro Yamamoto, more than 10,000 test samples of ore from the Iron Quadrangle region of Minas Gerais have already been analysed by the company. Yamamoto points out that, today, with technology, 90% of the iron ore from a low-content deposit can be efficiently recovered.

Currently, New Steel seeks to reduce operating costs by using industrial microwaves to dry the product. It aims to replace natural gas dryers, thereby cutting energy costs in half. “It is a sustainable process, but we have the challenge of making it more competitive,” Montenegro said.

Vale’s Director of Ferrous Metals Value Chain, Vagner Loyola, said the company has been developing technology to increase dry processing for years. Over the last decade, Vale invested almost $17.8 billion to deploy and expand the dry – or natural moisture – processing of the iron ore produced in Brazil. Over the next five years, it estimates it will invest $3.1 billion in similar processing facilities to achieve the goal of 70% dry production.

In Pará, almost 80% of production already uses this technology in Vale’s North System. The main plant in Carajás, Plant 1, is being converted to use natural moisture processing; from its 17 processing lines, 11 already use dry processing and the remaining six wet processing lines will be converted by 2023.

The treatment plants at Serra Leste (in Curionópolis) and the S11D complex (in Canaã dos Carajás) do not use water to treat the ore. At the S11D complex, for example, the use of the natural moisture processing route allows water consumption to be reduced by 93% when compared with the conventional method of iron ore production.

In Minas Gerais, dry processing was expanded from 20% in 2016 to 32% in 2019. Today, this type of processing is used by several units, such as Brucutu, Alegria, Fábrica Nova, Fazendão, Abóboras, Mutuca, and Pico. “In Minas Gerais operations, all the units that could be converted to dry processing production are already in operation,” Loyola explains. “Then, we are using tailings filtering and stacking as well as the dry concentration technology from New Steel to reduce the use of dams.”

Dry processing is associated with the quality of the iron ore from the mine face. In Carajás, as the iron content is already high (above 65% Fe), the material is only crushed and screened to be classified by size (granulometry). In some mines of Minas Gerais, the average content is 40% Fe in itabirite. To increase its grade, the ore is concentrated through processing with water and the tailings are disposed of in dams. Then, the high-grade ore resulting from this process can be transformed into pellets at the pelletising plants to increase the added value of the product.

The plants that use dry processing in Minas Gerais depend on the availability of high-grade ore – around 60% – that can be found in some mines of the state. To achieve the required quality and be included in Vale’s product portfolio, this ore must be blended with the ore from Carajás – this blending is carried out at Vale’s Distribution Centers in China and Malaysia.

Vale halts tailings disposal at Brucutu dam as it outlines dry stacking investments

Vale says it has taken the decision to temporarily suspend the disposal of tailings at the Laranjeiras dam, part of the Brucutu iron ore mine, in Minas Gerais, Brazil, while assessing the dam’s geotechnical characteristics.

During the shutdown, the dam will have the Level 1 emergency protocol adopted, Vale said. This does not require the evacuation of the downstream population, according to the National Mining Agency.

The Laranjeiras dam had its Statement of Condition of Stability issued on September 30, 2019, which remains valid, Vale clarified.

During the suspension period – estimated at 1-2 months – the Brucutu plant will operate with around 40% of its capacity through wet processing with tailings filtration and dry stacking, Vale said. This will reduce output by some 1.5 Mt/mth of iron ore.

The temporary stoppage does not lead to changes in Vale’s iron ore and pellet sales guidance, which remains, in 2019 and in the December quarter, at 307-312 Mt and 83-88 Mt, respectively.

For the March quarter 2020, production and sales are expected to range between 68-73 Mt, due to weather-related seasonality, the gradual and safe return of operations and in line with the margin over volume strategy, it said.

Despite this setback, Vale executives reiterated its ambitious ‘dry processing’ tailings plan at its Vale Day event in New York, yesterday.

The company said, in its Northern System, 81% of iron ore production was already through the dry processing route, while the Minas Gerais division had 32% of production through such means. Vale plans to convert 70% of its output to dry processing by 2023, compared with 60% today.

The company is investing $1.8 billion between 2020 and 2024 to help with this dry stacking aim, with the main sites operating converting to this solution being the Cauê, Conceição and Brucutu operations.

In addition to this, Vale executives said the company plans to produce the world’s first industrial-scale dry magnetic fines concentrate through the dry concentration innovations it acquired with New Steel in 2018. Vale plans to spend $100 million for 1.5 Mt/y of dry product, with start-up planned in 2022, according to the executives.

In addition to this, Vale said it had moved up its renewable energy plans at its operations and now intended to power its Brazil mines by only renewable means by 2025, compared with its previous 2030 goal. It would go global with 100% renewables by 2030, it added.

Tenova TAKRAF proves dry stack tailings credentials at Uzbekistan gold mine

Tenova TAKRAF says it recently installed three DELKOR overhead filter presses at a gold mine’s processing plant in Uzbekistan as part of its wider tailings dewatering system.

The system comprises three DELKOR overhead filter presses each processing around 120 m3/h of gold tailings. Each machine contains 177 mixed membrane filter plates with a size of 2 m x 2 m, and includes a high-pressure cloth washing system.

These filter presses form an important part of Tenova TAKRAF’s complete Dry Stack Tailings (DST) technologies solution, which covers processes from sedimentation to filtration and material handling, the company said.

The supply also included several pieces of ancillary equipment, including belt conveyors for cakes discharged from the filter press (each machine is equipped with a cake breaker), pumping skids for membrane inflation, filter cake washing pumps and high-pressure cloth washing pumps.

“The entire scope of supply, including the slurry feed pumps, is fully controlled and managed by state-of-the-art software,” the company said.

It added: “The complexity of the dewatering process required by this project clearly highlights DELKOR’s filter press potential across the dewatering spectrum. In fact, the filter press cycle includes filter cake squeezing, filter cake washing and filter cake air blowing, with the filter cakes washed with process water in order to remove unwanted residual cyanides from the dewatered cakes.

“Importantly, the required residual moisture content within the dewatered cakes was achieved immediately during start-up.”

Marco Zeni, Tenova DELKOR Project Manager, said: “Notwithstanding demanding site conditions, installation and commissioning, together with the required operational training, was successfully completed. With this project, we take another important step towards firmly establishing DELKOR also as a provider of filter presses to round up the filtration product portfolio and once again demonstrating that: it pays to talk to a specialist.”

FLSmidth notes sustainability and digital mining developments in Q2 results

FLSmidth’s June quarter saw an improvement in revenue and profitability as the company’s Mining and Cement divisions continued to perform strongly.

The company’s order intake for the June quarter amounted to DKK5 billion ($752 million), down 2% from the same period a year ago. Mining order intake, specifically, declined 7%, mainly due to a lower capital order intake, the company said. This included an order of around DKK375 million from Rio Tinto for its Koodaideri iron ore project.

During the quarter, the company also completed the acquisition of IMP Automation.

FLSmidth’s order backlog stood at DKK16.8 billion by the end of June, up 16% from the same time last year.

Revenue increased 16% year-on-year in the quarter to DKK5.5 billion on high activity level, while earnings before interest taxes and amortisation came in at DKK487 million, up 28% year-on-year.

FLSmidth Group CEO, Thomas Schulz, said: “The second (June) quarter showed a strong performance with improved revenue and profitability, driven by both Mining and Cement. Following a slow start to the year, we have been successful at converting backlog to revenue in the second quarter. In close cooperation with our customers, we have continued to deliver on our vision to provide sustainable productivity enhancement.”

Schulz continued: “Our success with both service and capital orders, demonstrates our customers’ confidence in our ability to enhance their productivity. This is supported by an increased push for sustainable solutions that ties in well with our position, capabilities and track record.”

In the company’s Mining division, Schulz said the company saw increased interest for new technologies such as dry stack tailings, but also a general need to reduce water consumption in the production process. The company said the mining market remained robust.

The company added on the mining market: “Equipment demand continues to evolve around replacement and brownfield projects, with select greenfield opportunities. Miners are attentive of rising global issues and remain cautious on large and high-risk investments. The long-term pipeline for larger projects is encouraging, but most projects are currently not reaching further than the engineering/prefeasibility stage.”

It continued: “Customers across regions and commodities are increasingly demanding digitalised solutions to improve performance, reduce operating costs and maximise safety in operations. Similarly, customers show increased interest in technology to obtain a more sustainable production, not least our effective solutions for tailings management given the latest issues with tailings dams failures and the related environmental impact.”