Tag Archives: dry-stack tailings

Yamana Gold retains electrification path for Wasamac in new study

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Yamana Gold has reiterated a plan to minimise the amount of carbon emissions generated with the development and operation of the Wasamac gold project in Quebec, Canada, in its first study since acquiring the asset from Monarch Gold.

Monarch, prior to being taken over by Yamana Gold, had laid out plans for an underground mine at Wasamac producing 6,000 t/d, on average, with an expected mine life of 11 years. It expected to use a Rail-Veyor® electrically powered, remote-controlled underground haulage system in addition to an almost entirely electric fleet of production and development equipment.

The December 2018 feasibility study by BBA indicated the Wasamac deposit hosted a measured and indicated mineral resource of 29.86 Mt at an average grade of 2.7 g/t Au, for a total of 2.6 Moz of gold, and proven and probable mineral reserves of 21.46 Mt at an average grade of 2.56 g/t Au, for a total of 1.8 Moz of gold. The study forecast average annual production of 142,000 oz of gold for 11 years at a cash cost of $550/oz.

With drilling, due diligence and further studies, Yamana Gold, in studies forming the new feasibility level studies, has come up with baseline technical and financial aspects of the Wasamac project that, it says, underpin the decision to advance the project to production.

This has resulted in a few changes to the Wasamac plan.

For starters, the company plans to use the extract the now 1.91 Moz of reserves quicker than Monarch’s strategy, with a rapid production ramp-up in the first year followed by sustained gold production of approximately 200,000 oz/y for at least the next four years.

Including the ramp-up phase, average annual production for the first five years of operation is expected to be 184,000 oz, the company said, with life of mine production of 169,000 oz/y. Mill throughput has been increased to 7,000 t/d, on average, but the plant and associated infrastructure were being sized for 7,500 t/d. Production could start up in the December quarter of 2026, the initial capital expense was expected to be $416 million and all-in sustaining costs over the life of mine had been calculated at $828/oz.

The use of a conveyor is still within this plan, but a company spokesperson told IM that Yamana was now considering a conventional belt conveyor rather than the Rail-Veyor system.

Yamana explained: “The optimised materials handling system uses ore passes and haul trucks to transport ore from the production levels to a central underground primary crusher. The haul trucks will be automated to allow haulage to continue between shifts. From the underground crusher, ore will be transported to the crushed-ore stockpile on the surface using a 3-km-long conventional conveyor system in two segments.”

Yamana added: “Using a conveyor rather than diesel trucks to transport ore to surface reduces CO2 emissions by 2,233 t/y, equivalent to taking 500 cars off the road. Over the life of mine, the company expects to reduce CO2 emissions by more than 20,000 t.”

The aim to use electric vehicles wherever possible remains in place.

“The Wasamac underground mine is designed to create a safe working environment and reduce consumption of non-renewable energy through the use of electric and high-efficiency equipment,” the company said. “Yamana has selected electric and battery-electric mobile equipment provided that the equipment is available at the required specifications.

“Battery-electric underground haul trucks are not yet available at the required capacity with autonomous operation, so diesel trucks have been selected in combination with the underground conveyor. However, Yamana continues to collaborate with equipment suppliers with the expectation that the desired battery-electric equipment will be available before Wasamac is in operation.”

In tandem with this, the company plans to use a ventilation on demand solution and high-efficiency fans to reduce its power requirements. This will likely rely on an underground LTE network.

“Heating of the underground mine and surface facilities is designed with the assumption of propane burners, but an opportunity exists to extend the natural gas line to the project site,” it added. “Yamana has initiated discussions with the natural gas supplier and will study this opportunity further as the project advances.”

The site for the processing plant and offices is confined to a small footprint strategically located in a naturally concealed area, and the processing plant has been designed with a low profile to minimise the visual impact as well as minimise noise and dust, according to Yamana.

The primary crusher, previously planned to be located on surface, has been moved underground, with the crushed material transported to surface from the underground mining area using conventional conveyors and stored on surface in a covered stockpile to control dust.

Several design improvements to the previous Wasamac plans have also been made to reduce consumption of fresh water to minimise the effect on watersheds, according to Yamana. Underground mine water will be used in the processing plant, minimising the draw of fresh water and reducing the required size of the mill basin pond.

The Wasamac tailings storage strategy is designed to minimise environmental footprint and mitigate risk, it added.

“Around 39% of tailings will be deposited underground as paste fill and 61% of tailings will be pumped as a slurry to the filter plant located approximately 6 km northwest of the processing plant and then hauled to the nearby dry-stack tailings storage facility,” Yamana said.

Strategic phasing of the tailings storage facility design allows for the same footprint as previously planned, even with the increase in mineral reserves, the company clarified. Also, the progressive reclamation plan for this facility minimises the possibility of dust generation and expedites the return of the landscape to its natural state.

Polymetal 2020 profits rise as it accelerates ESG efforts

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Polymetal recorded a strong set of financials in 2020, with its revenue, adjusted EBITDA and net earnings metrics all benefitting from higher production volumes and commodity prices.

Revenue increased by 28% year-on-year to $2.87 billion, adjusted EBITDA rose 57% to $1.69 billion and net earnings hit a record $1.09 billion in 2020.

The company’s 2020 gold-equivalent output amounted to 1.56 Moz, a 4% increase year-on-year and 4% above the original production guidance of 1.5 Moz. Strong contributions from its Kyzyl, Varvara and Albazino mines offset a planned grade decline at Voro, as well as lower production at Svetloye, the company said.

While production rose, the company’s greenhouse gas emissions intensity reduced by 4%, Polymetal said. It attributed this to energy efficiency initiatives, switching its mining fleet to electric vehicles, a shift from diesel to grid energy sources and green energy contracts.

Back in December, SMT Scharf AG signed an agreement with Polymetal to develop and produce battery-electric powered LHDs and mid-range underground trucks as prototypes for its gold and silver mines, with these units to be delivered to the company by October 2021.

Polymetal’s environmental, social and governance efforts did not stop there.

In 2020, the company invested $29 million at its Omolon hub in the Magadan region of Russia. This capital expenditure was mainly related to the construction of a dry tailings storage facility and engineering and preparatory works for a 2.5 MW solar plant (due to come online this year). This will be joined by another 5-10 MW solar facility at its Kyzyl operation (Kazakhstan) in 2022.

On its other tailings facilities, Polymetal said: “We operate eight tailings dams in Russia and Kazakhstan; each is rigorously monitored daily. We are confident that any emergency dam failure would have no impact on local communities and employees.

“We welcome the new Global Industry Standard on Tailings Management and have committed to achieving compliance in all operations by 2023.”

In addition to state authority inspections of these facilities, the company conducted an independent third-party audit of its Mayskoye (Chukotka, Russia) tailings site, which was carried out virtually, due to COVID-19 restrictions, by Knight Piésold Ltd. “To further improve tailings safety and minimise the risk of the possibility of dam failure, we are shifting towards dry stack storage methods,” it said.

“Such facilities are already in operation at our Amursk and Voro (pictured filter press) mines, and will be extended to Omolon (2021), Nezhda (2021), POX-2 (2022), Dukat (2024) and Veduga (2025).”

Euro Sun Mining plots Rovina Valley gold-copper production route in DFS

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Euro Sun Mining’s definitive feasibility study (DFS) on the Rovina Valley gold and copper project in Romania has outlined the development of two open-pit mines for a 21,000 t/d operation producing 132,000 oz of gold-equivalent over a 16.8-year mine life.

The company plans to use a phased development approach at Rovina Valley, with the development of the two open pit gold-copper deposits, Colnic and Rovina, included in the DFS and the exploitation of the Ciresata underground deposit (not included in the study) phased in following completion of open-pit mining. Ciresata is envisioned as a bulk underground mining operation and will be evaluated for its economic potential in a later study, the company added.

Estimated initial capital expenditure came in at $399 million (including $12.7 million in pre-strip), with average all-in sustaining costs of $813/oz of gold-equivalent. Using $1,550/oz gold and $3.30/lb copper prices, the post-tax net present value (5% discount) came in at $359 million.

These results were broadly in line with a May 2020 target of outlining a DFS with an 18-year mine life, with initial capital expenditure in line with the preliminary economic assessment – which showed off a capital expenditure bill of $339.7 million.

The Rovina Valley project is planned to be mined with a standard open-pit mining method using articulated trucks and a hydraulic loader. The open-pit mining operation is anticipated to last around 16.5 years, during which the lower-grade material will be stockpiled on a pad close to the primary crusher location for treatment over another 18 months. The DFS incorporates simple flotation without the use of cyanide and dry-stack tailings, the company said.

On the latter, the company said: “KCB have designed a waste management facility within the project area for the co-deposition of waste rock and filtered rougher tailings. Process plant rougher tailings will be filtered in the plant where the resultant filter cake will be transported by conveyors and will be co-mingled with waste rock prior to deposition. The cleaner tails will be filtered separately from the rougher tailings and the resultant filter cake will be transported by conveyors and deposited separately within a lined zone contained within the boundary of the co-mingled facility and will be stored separately in a lined zone of the waste management facility.”

Euro Sun said the design had been engineered to reduce the risk of development of impacted seepage from potentially acid-generating waste rock and capture the impacted seepage from the cleaner tailings.

“After completion of mining the Colnic pit, the waste rock and rougher tailings will be preferentially backfilled into the Colnic pit, while the cleaner tails will continue to report to the lined zone of the waste management facility,” it added.

The company said it is targeting first production from Rovina Valley in 2024.

Bluestone widens production plans with Cerro Blanco open-pit mining PEA

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Bluestone Resources has come out with a new open-pit mining plan for its Cerro Blanco project in south-eastern Guatemala that effectively doubles production and triples the potential investor returns from the gold-silver asset.

The preliminary economic assessment on Cerro Blanco, which comes just under 11 months after entering into an agreement with G Mining Services covering basic engineering and overall project optimisation efforts for the project, outlines a project able to produce 231,000 oz of gold at an all-in sustaining cost of $642/oz Au over the 11-year life of mine. This is based on a 15,000 t/d operation with a $548 million initial capital expenditure bill.

Using a base case gold price of $1,550/oz and silver price of $20/oz, an after-tax net present value (5% discount) of $907 million was calculated.

The numbers are significantly different from what the company outlined in a previous feasibility study on Cerro Blanco, completed by a consortium of independent consultants led by JDS Energy & Mining. This showed an average output of 113,000 oz/y of gold at an all-in sustaining cost of $579/oz and a capital cost of $196 million (including contingency).

Using a base case of $1,250/oz gold and $18/oz silver, this underground project was estimated to generate a post-tax net present value (5% discount) of $241 million.

Bluestone said on the PEA publication: “The recent completion of advanced engineering and optimisation work has significantly enhanced the understanding of the project and presented an opportunity to capitalise on its near-surface, high-grade mineralisation through an open-pit development scenario. This is a major change to Bluestone’s corporate strategy that will fully maximise the value of the Cerro Blanco gold project for all stakeholders.”

David Cass, Vice President of Exploration, added: “The pivot to surface mining is a culmination of our increased understanding of the geology and grade distribution that will realise the full potential of the Cerro Blanco low-sulphidation mineralisation. The inverted wedge shape of the deposit with its upper half forming the Cerro Blanco hill lends itself to surface mining with a low strip ratio.”

The project currently hosts 3 Moz of gold in the measured and indicated resource category and 250,000 oz of gold in the inferred mineral resource category.

The open-pit mining scenario envisages an owner-operated mining fleet using 65-t trucks matched with 7 cu.m hydraulic shovels supported by 8.2 cu.m wheel loaders. Mill feed will be trucked to a primary crusher located to the east of the main pit. Waste totalling 123.5 Mt will be placed in a waste storage facility.

In terms of processing, the PEA looks at treating 5.04 Mt/y of mineralised material at an average feed grade of 1.6 g/t Au and 7.26 g/t Ag through a conventional cyanide leach process plant to produce doré. The flowsheet is very similar to the previous underground mine option and includes primary crushing, single train SAG mill and ball mill to produce a target grind size of 80% passing 53 microns, atmospheric pre-oxidation, 48-hour cyanide leach, carbon-in-pulp carousel adsorption circuit, Zadra elution circuit, gold room and filtered tailings. Based on PEA metallurgical test work, the expected recoveries are 91% for gold and 85% for silver.

Filtered tailings will be configured in a dry-stack facility and eliminate the need for the construction and operation of a traditional tailings impoundment, the company says.

“The adoption of this technology (dry stacking) puts the Cerro Blanco project at the forefront of responsible mining practices being adopted for the future of sustainable mining globally,” it added.

Autonomous loading and hauling pays off at Agnico’s LaRonde, Kittila gold mines

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Increased uptake of autonomous loading and hauling technology at the LaRonde (pictured) and Kittila gold mines has helped Agnico Eagle Mines post a record quarter of production for the last three months of 2020.

Payable gold production in the fourth quarter of 2020 was 501,445 oz at all-in sustaining costs of $985/oz, the company reported. This compared with 494,678 oz at an AISC of $1,039/oz in the prior-year period.

Homing in on LaRonde Complex (including the LaRonde mine and the LZ5 Mine), in Quebec, Canada, Agnico put the good performance at LaRonde – production of 105,729 oz during the quarter, down from 112,704 oz in the prior-year period when gold grades were 7.3% higher – down partially to the automation strategy that, the company said, had helped improve productivity and allow continuation of mucking activities during non-entry protocols related to seismicity.

In 2020, 13% of tonnes mucked from stopes at the LaRonde mine were carried out in automation mode and, in December 2020, a record 39% of the production mucking at the LaRonde mine was carried out from surface, which included 100% of the production mucking from the West mine area.

At LZ5, in 2020, 14% of tonnes mucked and hauled to surface were accomplished in automated mode with operators based on surface. This surpassed the 15% target the company had set. For 2021, it is expected 17% of the tonnage will be mucked and hauled remotely to surface and the production rate is expected to be sustained at around 3,000 t/d. “The LZ5 automation team will continue optimising the automated mining techniques,” Agnico said.

Agnico said the target for 2021 is to muck over 17% of the total tonnage for the LaRonde Complex from surface. The company said it is also carrying out work to perform production drilling using automation.

In a January presentation, Agnico stated that 10 LHDs and four trucks had been equipped with Sandvik’s AutoMine® system. Back in 2018, Sandvik announced that the LaRonde mine would become the first operation to use AutoMine with LTE communication network underground on a production scale.

To continue tailings deposition through the LaRonde Complex life of mine, Agnico is also constructing dry-stack tailings facilities, which are expected to be operational by the end of 2022. Dry stacking will help limit the footprint of the new tailings facility and improve the closure of the main tailings ponds, Agnico said.

Moving to Finland at the Kittila gold mine, the use of automation also paid off.

The company said Kittila continued delivering strong performance in the December quarter of 2020, with production above forecast by around 6,000 t. This also coincided with the commissioning of the expanded mill at Kittila, which is now ramping up towards the design capacity of 2 Mt/y.

The mine delivered a record full-year ore production of around 1.85 Mt in 2020, according to the company.

“This performance (in Q4) is driven by an improved fleet management and an increased usage of automation,” Agnico said.

Kittila has been testing autonomous hauling trucks and tele-remote equipment and is targeting to achieve 50% of production drilling and 15% of hauling remotely in 2021, it said.

On top of this, Agnico said the mill had consistently increased availability and the company was evaluating the implementation of advanced process control in 2021.

Capstone prepares Cozamin for introduction of paste backfill, dry-stack tailings

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An updated Technical Report on Capstone Mining’s Cozamin copper-silver mine in Zacatecas, Mexico, has shown the potential for a mine life extension to 2031, and a plan for dry-stack tailings and underground paste backfill. At the same time, the company says it is studying the use of “innovative mining techniques and enhanced pillar recovery” to make the most of existing reserves and resources.

The updated life of mine plan released outlined average annual copper production of 51.2 MIb (23,224 t) of copper and 1.6 Moz of silver production over 10 years at average C1 costs, including the 50% silver stream, of $1.02/Ib of payable copper. From 2021 to 2027, average annual production is slated to be 58.8 MIb of copper and 1.7 Moz of silver.

The company said a planned ramp-up to 3,780 t/d, or 1.38 Mt/y, by the end of March quarter is on track, with a new section of ramp to open the one-way traffic circuit to debottleneck the mine (pictured) completed in early December 2020, ahead of schedule.

Reserves increased by 39% and now stand at 14.1 Mt, relative to April 30, 2020. Contained copper and silver increased by 37% and 49%, respectively, with around half of this increase due to recovery of high-grade pillars using paste backfill, Capstone said.

The miner said “tailings management transformation” activities were progressing on schedule at site, including feasibility-level design and studies in support of permitting a filtered (dry stack) tailings storage facility.

“This conversion from a slurry tailings impoundment aligns with industry leading socio-environmental best practice for tailings management,” the company said.

Meanwhile, a prefeasibility study (PFS) for an underground paste backfill system was completed in December.

The study indicates a paste backfill system will allow ore extraction containing over 100 MIb of copper and 3.1 Moz of silver between 2023 and 2031, which would have otherwise been left as unmined pillars. The PFS design has a capital cost estimate ranging from $41-$45 million and an increase in operating costs of around $7.50/t of ore mined. Capstone says its management has approved the paste backfill project and work has commenced on procurement of long lead items.

The proposed paste backfill system includes a tailings filter plant, a paste mixing plant, twin boreholes to deliver paste underground and an underground distribution system. The system is expected to be commissioned starting in the December quarter of 2022, with ramp-up completed in the March quarter of 2023.

PFS design of these facilities was completed by Paterson & Cooke in December 2020 and a feasibility study is underway with completion expected in April 2021. Mine planning was completed by Cozamin, with design support provided by a geotechnical consultant, and paste backfill operational guidance provided by AMC Consultants.

Within the latest release, Capstone also flagged the initiation of its “Impact23 Growth” project, which has identified areas of exploration excellence, innovative mining techniques and enhanced pillar recovery at Cozamin.

“By 2023, the goal is to further extend mine life, increase environmental and safety standards, and improve operational efficiencies at Cozamin, utilising mineral resources already discovered in addition to testing new targets,” the company explained.

Included among the options are the innovative mining techniques for resource to reserve conversion flagged at the start of this story.

Capstone says a study will be initiated this year to assess alternative mining techniques with the objective of lowering costs and dilution to convert resources to reserves from the indicated resource base. The current mining methods are longitudinal longhole open stoping and AVOCA, with possible alternatives to be studied including cut-and-fill, drift-and-fill and longhole open stoping with ore sorting technology.

Brad Mercer, Capstone’s SVP and Chief Operating Officer, said: “The life of mine plan announced today maximises extraction of the orebody’s high-grade core by deferring stoping in this area until the paste backfill plant is in operation in 2023. Projected production averages nearly 60 MIb of copper per year for seven years at first quartile costs.

“The Impact23 Growth project that we are kickstarting today is aiming to demonstrate in a 2023 technical report how Cozamin can sustain these levels of performance well into the 2030s.”

Darren Pylot, Capstone’s President and CEO, added: “After 14 years in operation, the best years of Cozamin are ahead. The mine is world class with sustainable low costs and leading safety and environmental performance entrenched throughout the organisation. The growth initiatives are supported by an entrepreneurial fabric at Capstone, as we embrace innovation and technology to create high impact value for our shareholders.”

FLSmidth to deliver dry-stack tailings solution at Hindustan Zinc’s Rajpura Dariba mine

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FLSmidth has been contracted to deliver an integrated dry-stack tailings solution and a paste fill plant to Hindustan Zinc’s lead-zinc mine in Rajpura Dariba, Rajasthan.

The solution will ensure environmental sustainability and significant process water recovery, as well as reduce the footprint of the tailings storage facility, the mining OEM said.

The new order, which was booked in the December quarter, includes design, engineering, procurement, supply of equipment and the commissioning for integrated dry tailings and stacking along with tailings paste fill plant. FLSmidth will also supply two Automatic Filter Presses (AFP-IV™, pictured), two E-Disc filters and one 26 m diameter High-Density Thickener as the main pieces of equipment. The project is expected to be completed by February 2022.

This new order follows a previous tailings-related order for Hindustan Zinc at its Zawar mine site in 2018.

Hindustan Zinc operates beneficiation plants at Rajpura Dariba and Sindesar Khurd, which both discharge tailings to the same tailings pond. The tailings dam was reaching capacity for conventional wet tailings deposition and so Hindustan Zinc needed a way to resolve this issue, FLSmidth said.

The solution the company required would involve creating a small dry-stack tailings area with minimal environmental and physical footprint and also a method to backfill the mine by using an adjusted dry filter cake mix.

By choosing FLSmidth’s hybrid technology – a combination of the E-Disc filter and the AFP-IV Automatic Pressure Filter – Hindustan Zinc will now be able to achieve this and recover around 85% of process water, according to FLSmidth. This recovered process water can be reused by the process plant located at the mine site with minimum operating and capital expenses.

The cake from the E-disc filter will contain below 16% moisture and can be used for mine backfilling, while the cake from the automatic filter press, with below 12% moisture, can be stacked on the surface in a safe and compact manner, FLSmidth says.

“The solution will also significantly reduce industrial water consumption, something that is of heightened importance in water-scarce areas, such as Rajasthan,” the company said. “The site will also have zero effluent discharge, further boosting its sustainable mining goals.”

Manfred Schaffer, Mining President, FLSmidth, said the order was another strong “proof point” for the quality and flexibility of the company’s technology for filtration and engineering solutions for tailing management.

“This project resolves the customer’s challenge through optimum utilisation of available space and ensures the paste backfill requirements are met with the lowest possible operating and capital costs,” he added. “Importantly, it also secures a high level of reusable water for the mine site, which helps their sustainability efforts and supports our own MissionZero ambition.”

Los Andes Copper commits to HPGR comminution route for Vizcachitas

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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.”