Tag Archives: gold

Suntrace, BayWa re, B2Gold commission ‘world’s largest’ off-grid solar-battery system

Suntrace GmbH and BayWa re, together with B2Gold, have completed commissioning of what they say is the world’s largest off-grid solar-battery hybrid system for the mining industry at the Fekola gold mine in Mali.

The solar-battery hybrid plant was integrated and commissioned successfully with the existing power plant operation, with the solar plant on course to be 100% complete by the end of June.

Hybrid projects such as this, which combine solar energy with conventional energy generation and battery storage, are an effective way to provide reliable power supply day and night in off-grid areas, Suntrace says. “Ideally suited to their needs, B2Gold approved the hybrid project for implementation in July 2019, following completion of preliminary studies by Suntrace and BayWa re.”

The Fekola gold mine operates 24-hours a day. During the daytime, the new 30 MW solar plant allows three out of six heavy fuel oil generators to be shut down; the energy production of the residual three generators could also be significantly reduced. The 15.4 MWh battery storage compensates for energy generation fluctuations and assures a reliable operation, which allows up to 75% of the electricity demand of the gold mine to be covered by renewable energy during the daytime, Suntrace said.

Dennis Stansbury, Senior Vice President at B2Gold, said: “Suntrace and BayWa re have played a vital role in our work towards more sustainable production at Fekola. The implementation of a solar-battery hybrid system was an obvious choice to help achieve this, not only for its environmental credentials, but also its economic viability. This is a landmark project which we expect to pave the way for more sustainable power generation within the mining industry in West Africa.”

The integration of the solar power plant with the battery system will ensure safe and reliable power, saving 13.1 million litres of heavy fuel oil a year.

Martin Schlecht, COO of Suntrace, said: “We are very proud that B2Gold has entrusted Suntrace, together with BayWa re as engineering and procurement contractor, to support the development and implementation of this innovative project. Thanks to excellent team work with B2Gold and BayWa re, we were able to manage the completion despite the global challenges that the COVID-19 pandemic imposed on all of us. We are proud to jointly deliver a functioning project, well integrated with the mining operations, which reduces CO2 emissions from power generation for the Fekola mine by roughly 20%.”

The photovoltaic-battery system will help to reduce CO2 emissions by 39 000 t/y, according to the company.

Thorsten Althaus, Project Manager at BayWa re, added: “Integrating such a large amount of solar into a small, isolated grid safely and reliably has been a major technical challenge and required the use of battery storage as well as a tailor-made control system. This was conceptualised in the early stages of the project and we ensured that our vision was implemented accordingly by the suppliers. It is extremely rewarding to see how well this solution performs in reality and shows that the technology works and is just waiting to be applied on further projects.”

Turquoise Hill and Rio Tinto sign Oyu Tolgoi UG funding HoA, agree to end arbitration

Turquoise Hill Resources and Rio Tinto have entered into a binding Heads of Agreement (HoA) to provide an updated funding plan for the completion of the Oyu Tolgoi underground copper-gold project in Mongolia.

The funding plan is designed to address the estimated remaining funding requirement of around $2.3 billion and replaces the non-binding Memorandum of Understanding that Rio and Turquoise Hill previously entered into on September 9, 2020.

Under the HoA, subject to securing approval by Oyu Tolgoi LLC, the project joint venture, and any required support from the Government of Mongolia, Turquoise Hill and Rio Tinto will:

  • Pursue re-profiling of existing project debt to better align with the revised mine plan, project timing and cash flows to reduce the currently projected funding requirements of OT by up to $1.4 billion; and
  • Seek to raise up to $500 million in senior supplemental debt (SSD) under the existing project financing arrangements from selected international financial institutions.

In addition, Rio Tinto has committed to address any potential shortfalls from the re-profiling and additional SSD of up to $750 million by providing a senior co-lending facility on the same terms as Oyu Tolgoi’s project financing, while Turquoise Hill has committed to complete an equity offering of up to $500 million.

An updated feasibility study on the underground expansion at Oyu Tolgoi from June 2020 included a delay of 21 to 29 months for first sustainable production compared with the original 2016 feasibility study guidance and an increase of $1.3-$1.8 billion from the original $5.3 billion development capital. The process also saw 1.22 Mt of copper, 850,000 oz of gold and 7.01 Moz of silver removed from the Hugo Dummett North reserve base compared with the December 31, 2019 calculation, with some 80,000 t of copper, 70,000 oz of gold and 550,000 oz of silver added to the Hugo Dummett North Extension reserve base.

Since this announcement, Rio, Turquoise Hill and the Government of Mongolia have been trying to agree on a new funding pact for the sustainable development of the underground operation, which, in combination with open-pit mining, could produce around 500,000 t/y of copper at full capacity.

Steve Thibeault, Interim Chief Executive Officer of Turquoise Hill, said: “We are pleased to have reached a constructive and equitable agreement with Rio Tinto to fund the Oyu Tolgoi underground development. With a binding funding agreement now in place that sets out a process along a known timeline, we will be able to move ahead as expeditiously as possible with the development of the underground project at Oyu Tolgoi.

“We remain committed to continue delivering a benefit to all stakeholders, including Mongolia and its citizens, and to delivering significant long-term value for Turquoise Hill as this project progresses.”

Rio Tinto Copper Chief Executive Bold Baatar, added: “This agreement and alignment with Turquoise Hill represents a major milestone in the continued development of Oyu Tolgoi, which is expected to become one of the world’s largest copper mines and a significant contributor to the Mongolian economy for years to come. Commencing the re-profiling whilst concurrently listening, engaging and resolving the concerns of the Government of Mongolia are critical steps to maintaining momentum on the timely delivery of the Oyu Tolgoi Underground project.”

Following the HoA, Turquoise Hill and Rio have agreed to obtain an order dismissing the current arbitration on a “without prejudice basis” and without costs, including an order vacating the interim measures order, the companies said.

COREM, Steinert ore sorting tests present opportunities for Cartier at Chimo gold project

Cartier Resources says ore sorting tests carried out by COREM and Steinert US on mineralised samples from the Chimo Mine property, in Quebec, Canada, have indicated gold grades could increase substantially with the use of the pre-concentration technology.

Gold from Chimo is present in two types of mineralised facies: i) quartz veins with coarse visible gold grains having an affinity for the gravity concentration of gold at the mill and ii) zones of silica-rich mafic rocks associated with non-refractory arsenopyrite having an affinity for the flotation of a concentrate of arsenopyrite for gold recovery at the mill.

To perform the sorting tests, rocks representative of the two mineralised facies, made up of the following six mineralogical facies, were first selected for static recognition of each of the facies by the sensors of the sorter:

  • Gold-bearing quartz veins;
  • Gold-bearing silica;
  • High grade gold-bearing arsenopyrite;
  • Medium grade gold-bearing arsenopyrite;
  • Low grade gold-bearing arsenopyrite; and
  • Mafic waste rock.

The detection sensors of the industrial sorter at COREM in Quebec, Canada, were the RGB camera using the optical properties of reflection, brightness and transparency to locate quartz and silica and the X-ray Transmission sensor using the volumetric property of atomic density to locate arsenopyrite. The two sensors adequately recognised the six mineralogical facies associated with the mineralisation, with dynamic calibration tests of the sorter with the moving conveyor making it possible to sort, one at a time, 2 kg samples of each of the facies, Cartier said.

The results of this first test at COREM showed the first three sorts (on a total of eight sorts) concentrated 99.1% of the gold contained in 44.4% by mass of material mass for a grade of 56.3 g/t Au, representing a percentage increase of 223% in gold content over sorter feed. The reject, representing 0.9% by mass of material, contained only 0.4 g/t Au.

The sorter was then ready to perform sorting tests on the 105.7 kg production sample, representative of the mineralised facies at an average grade of 2.16 g/t Au. This content was obtained by including 20% by mass of material with zero grade of gold, simulating dilution in the stopes. COREM’s sorting plan separated 53.9% by mass of the material in the form of a preconcentrate at an average grade of 3.68 g/t Au, representing an increase of 170% in the gold grade compared with the sorter feed. The waste disposal, separated from the mineralisation, represented 46.1% by mass of material at an average grade of 0.38 g/t Au.

Sorting tests carried out with Steinert in Kentucky using a Steinert KSS FLI XT machine with XRT, colour, laser, and induction sensors yielded comparable results.

A 80.69 kg production sample, representative of the mineralised facies at an average grade of 2.13 g/t Au, to which 20% by mass of material at zero grade of gold was added mathematically, representing the dilution in the workings, was used for testing. The new calculated diluted grade was 1.55 g/t Au.

Calculation of the results revealed that 51% by mass of the dilute grade material could be separated as a preconcentrate at an average grade of 2.72 g/t Au, representing a 175% increase in gold grade compared with the sorter feed. The waste disposal, which would be separated from the mineralisation, would represent 49% by mass of material at an average grade of 0.36 g/t Au.

Sorting tests with COREM were carried out following these tests to validate that the 20% of dilution material at zero grade of gold, mathematically added, could physically be effectively separated by the sorter, Cartier said.

The sorting tests carried out by both COREM and Steinert US were comparable, with these results providing prospects for increasing the value of the resources with ore sorting technology.

The objective of the industrial sorting of the mineralisation is to increase the grade of the preconcentrated material preceding the milling operations, which allows an increase in the recovery rate at the mill, reduces transport costs to the mill, reduces milling costs, reduces the costs of environmental restoration of mine tailings, and reduces the environmental footprint of mine tailings and, consequently, increases the social acceptability of the mining project, Cartier said.

The most recent resource estimate from Chimo included 6.6 Mt at an average grade of 3.21 g/t Au for a total of 684,000 oz of gold in the indicated category and 15.2 Mt at an average grade of 2.77 g/t Au for a total of 1.36 Moz of gold in the inferred category.

Wiluna Mining lays renewable energy groundwork with Contract Power extension

Wiluna Mining Corp has signed a 10-year contract extension with Contract Power Group that will see the power provider charge up the Wiluna Mining Operation in Western Australia until at least 2031.

The contract is geared towards meeting the forward needs of the Stage 1 development project at Wiluna, to provide a total rated power output of the power station of 14.1 MW. It will also re-configure the power station to increase gas generation and add a 2 MW battery energy storage unit to significantly reduce the need for back-up diesel generation, with four diesel generators being removed.

The new pact will also allow amortisation of costs over a longer period, therefore reducing Wiluna’s overall operating power charges; the company said.

And, when it comes to the Stage 2 development expansion project in 2023 at Wiluna, the contract will provide a solid base for a future mixed renewables power station, the company said.

Back in October, Wiluna Mining’s board gave the thumbs up to the Stage 1 development, which will see the company transition from its current production profile of producing 62,000 oz/y from mining free milling ore through the current 2.1 Mt/y carbon-in-leach processing facility, to initially producing 100,000-120,000 oz/y of gold and gold in concentrate. This will be implemented using the current, recently refurbished crushing circuit, the previously expanded mill circuit and a new 750,000 t/y concentrator by October 2021, the company said.

Wiluna then intends to increase production of gold and gold in concentrate by, at a minimum, doubling the mining rate and the concentrator to produce circa-250,000 oz/y by the end of 2023/early 2024 as part of Stage 2.

Contract Power, a subsidiary of Pacific Energy, has provided Wiluna’s power – a mix of natural gas and diesel power backup – since June 2016.

“Contract Power Group are experts in efficient generation of electrical power and in decarbonisation by harnessing off-grid wind or solar power,” Wiluna said. “Wiluna are refining its plans with Contract Power Group to include decarbonisation within our methods of power generation at site. This may also moderate our exposure to future volatility in the cost of hydrocarbon fuels.”

Wiluna will now focus on renewable power studies and options during 2021 and 2022 to:

  • Assess the right mix of renewables including solar, wind or pumped storage options;
  • Determine how best to integrate renewables into the total power delivery for an expanded operation; and
  • Optimise the decarbonisation of power generation with reliability and cost effectiveness.

Milan Jerkovic, Wiluna Mining’s Executive Chair, said: “We look forward to working with Contract Power to not only transitioning the Wiluna Mine once again into one of Australia’s biggest and most profitable gold mines, but to helping it become one of Australia’s cleanest mines.”

Telson Mining ready to experiment with metallurgical innovations at Campo Morado

Telson Mining, following a strong quarter of production from the Campo Morado mine, in Guerrero State, Mexico, is making plans to boost throughput and recoveries through the potential use of grinding, leaching and flotation technologies from the likes of Maelgwyn Mineral Services, Core Group and Glencore Technology.

The mine’s throughput averaged out at 58,100 t/mth in the March quarter, with total throughput for the quarter of 174,400 t being 4% higher than the December quarter. Some 11,013 t of zinc concentrate and 1,907 t of lead concentrate was produced over the period, compared with 9,974 t and 1,916 t, respectively, in the previous quarter.

Gold, silver, lead and zinc recoveries all improved, quarter-on-quarter, in the first three months of the year, the company added.

Ralph Shearing, Telson CEO and President, said: “These strong first quarter results continue to reflect our steady progression of improving the throughput and recoveries at Campo Morado. To this end, management intends to initiate a rigorous metallurgical testing program to advance through second phase testing the Leachox™ Process of Maelgwyn Mineral Services and the Albion Process™ of Core Group, both of which returned positive test results in first phase testing.”

He said this metallurgical testing program will also study the ability to increase base metal recoveries at microfine grinding with flotation recovery using Imhoflot Flotation (also Maelgwyn) and Jameson Cell (Glencore Technology) flotation technologies, both designed for such purposes.

“We are confident that additional recovery improvements are available utilising these exciting modern technologies which, if successful, can provide increased revenue streams,” Shearing added.

Maelgwyn’s Leachox Process consists of several Maelgwyn proprietary processes linked together including Imhoflot G-Cell flotation technology, ultra-fine grinding using the Ro-Star mill, Aachen Reactors and Aachen assisted cyanide destruction.

The Albion Process, meanwhile, is a combination of ultrafine grinding and oxidative leaching at atmospheric pressure. The feed to the Albion Process is refractory base or precious metal concentrates, where the sulphides in the feed are oxidised and liberated, allowing the target metals to be recovered by conventional means.

New Major Drilling rod handling rigs start turning at Hecla’s San Sebastian mine

Two new Major Drilling EF-75 drills have arrived and are now turning at Hecla Mining’s San Sebastian mine in Durango, Mexico, the drilling services company says.

The drills arrived in March and are part of Major Drilling’s fleet improvements, adding innovative rod handling capability to the project, it said.

“We are thankful that we are partnered with a company like Major Drilling that can provide newer, innovative drills,” Stephen Redak, Exploration Manager Mexico, Hecla Mining, said.

Hecla’s San Sebastian property is a silver and gold mine, where exploration work is underway in two main veins. Using these new drills at the San Sebastian project enhances Major Drilling’s 12-year history with Hecla in Mexico. This has seen more than 354,000 m drilled since 2009.

Major Drilling’s EF-75 core drill is new equipment for the Mexico branch. It combines safety with a high level of productivity, according to the company.

With the rod manipulator, operators benefit from rod handling, horizontal stacking and a safety screen to protect them while lifting and lowering rods. The rig is capable of depths of up to 2,700 m.

Workers are protected by rod handling innovation, and they improve results using a unique mast designed for accurate core orientation, the company says.

David Boucher, Major Drilling Mexico General Manager, said: “Hecla has been a long-time client of ours in Mexico, and we are very excited to bring these new drills out in Durango to really see what they can do at San Sebastian. We are very happy to have this equipment turning in Mexico.”

Major Drilling’s USA Division previously partnered with Hecla at the Fire Creek Mine in Nevada (now under care and maintenance). The company’s exploration teams have also drilled at Hecla surface exploration projects in other locations in the western USA.

Foran Mining assembles FS team for ‘world first’ carbon neutral copper mine project

Foran Mining says it has bolstered the design team for its ongoing definitive feasibility study at the McIlvenna Bay project, in Saskatchewan, Canada, providing the company with the technical expertise to execute on its strategy of building the world’s first copper mine designed to be “carbon neutral” from day one of production.

The advisors are anticipated to employ a range of technologies and initiatives in the design of the mine and processing facilities to materially reduce greenhouse gas emissions and the environmental impact of the operations.

Foran says its due diligence to date has highlighted the potentially superior returns achievable through implementing this strategy, while the use of battery-electric vehicles will also be safer for employees, reducing risk of injury and physical stressors, such as vibration and noise.

The FS team includes experts from:

  • Stantec – mine design and engineering;
  • Knight Piésold Ltd – tailings storage facility design;
  • Halyard Inc – process plant design;
  • Micon International Limited – resource estimate;
  • Base Metallurgical Laboratories Ltd – metallurgical testing;
  • Canada North Environmental Services Ltd – environmental; and
  • Synergy Enterprises – sustainability and carbon accounting

Dan Myerson, Executive Chair of Foran, said: “The appointment of these world-class environmental and engineering specialists reflects our ambition to develop a technically and economically compelling solution to the environmental and social challenges which have been traditionally associated with the sector. We are therefore thrilled that professionals of this calibre have agreed to support us on this journey.”

He added: “Together, we intend to ensure that our operations emit net zero greenhouse gases and set new safety benchmarks for the industry, while also ensuring that the local community and the broader Canadian population benefit from our operations. The responsible production of copper and zinc is critical as the world transitions to a low carbon future; these metals are used in the production of renewable energy assets and electronic industries, for example. We look forward to providing more updates, in relation to our infill and expansion drilling, as well as announcing more detailed plans about how we will be putting our ambitions into practice.”

The 2020 prefeasibility study on McIlvenna Bay envisaged a 3,600 t/d underground operation with on‐site crushing and mineral processing facilities, a paste plant and filtered tailings storage facility. It considered a nine-year life of mine and scheduled treatment of the full reserve of 11.34 Mt grading 4.01% Zn, 1.14% Cu, 0.54 g/t Au and 20.97 g/t Ag. It also included plans for McIlvenna Bay to be an early adopter of battery-electric haul trucks.

Foran recently commenced its largest drill program ever (pictured), with over 30,000 m of infill and expansion drilling in the deposit. This has been designed to maximise the conversion of the current inferred resource to the indicated resource category, which can then be interrogated for inclusion in the updated reserve statement.

Foran says the feasibility study will, among other things, look to:

  • Further optimise and detail the McIlvenna Bay project engineering, including the estimation of reserves, mine design, stope sequence, development and production schedules;
  • Refine power and equipment requirements to support the company’s commitment to carbon neutral operations;
  • Update and detail the design and feasibility of the tailings desulphurisation process, dry stack storage facility and cemented paste backfill processes;
  • Provide detailed construction scheduling, including optimisations that would arise from pre-fabrication and/or modular (off-site) construction to the greatest extent possible;
  • Identify further mine optimisation to increase productivity and reduce operational expenditures; and
  • Consider equipment usage and activities where greenhouse gas emissions can be eliminated, reduced or offset to ensure that McIlvenna Bay is a carbon neutral operation.

Red 5 taps Zenith Energy for hybrid power options at King of the Hills gold project

Red 5 Ltd has entered into a Power Purchase Agreement with a subsidiary of Zenith Energy Ltd that will see the growing Australia-based power producer build, own and operate approximately 30 MW of hybrid power generation capacity to service the needs of the King of the Hills (KOTH) project in Western Australia.

The power inputs as part of the BOO agreement comprise high efficiency reciprocating gas fuel power generation together with a 2 MW photovoltaic solar farm (an example from Zenith’s other work shown above) and a battery energy storage system.

Power supply to the site is planned to commence in the March quarter of 2022 with an initial term of 10 years. The contract includes provision for a potential future upgrade to the power station to support increased plant throughput beyond the initial planned 4 Mt/y run rate, Red 5 says.

Gas will be supplied from the Goldfields Gas Pipeline, 12 km west of the mine, under separate contracts, the company clarified.

Red 5 Managing Director, Mark Williams, said the award of the agreement marked another important construction milestone for the King of the Hills project while, at the same time, helping to achieve one of the company’s environmental, social and governance commitments to reduce the carbon footprint of the project.

“We are pleased to have signed the Power Purchase Agreement with Zenith, an experienced power producer which provided us with a compelling hybrid thermal and sustainable power solution that includes renewable energy,” he said. “Zenith’s combination of a gas and solar power station, supported by a battery energy storage system, provides the efficiency and stability required for the processing plant and infrastructure to enable King of the Hills to be a long-life, low-cost gold producer.”

The KOTH project is an open pit and underground gold deposit with a projected mine life of over 16 years. This could see the company produce 176,000 oz/y of gold over the first six years, according to a recent feasibility study.

Roxgold lays Séguéla groundwork with Metso Outotec, Lycopodium contract awards

Roxgold says it has awarded a SAG mill order for the Séguéla gold project in Côte d’Ivoire to Metso Outotec as part of its efforts to advance the project through to construction in the coming months.

The move comes ahead of the release of feasibility study on the project next month, which will build on a 2020 preliminary economic assessment (PEA) that outlined an operation capable of delivering over 100,000 oz/y of gold over eight years at average all-in sustaining costs of $749/oz. This study also incorporated a single stage primary crush/SAG milling comminution circuit with 1.25 Mt/y throughput.

At the same time as selecting Metso Outotec for the SAG mill contract, Roxgold has awarded preferred contractor status to Lycopodium Minerals Pty Ltd and is currently negotiating the engineering, procurement, and construction (EPC) agreement with the company for the 1.25 Mt/y carbon-in-leach processing facility and other supporting infrastructure to be constructed at Séguéla.

The fixed price agreement increases confidence in the total capital cost for the project, as it is by far the largest scope at Séguéla, Roxgold said.

“With this agreement in the final stages of negotiation and several other key scopes now tendered and priced, approximately 65% of the pre-production capital estimate has now been fixed or finalised,” the company added. “This level of detail provides increased confidence around the pre-production capital estimate, which is expected to be in-line with the previous estimate of $142 million, as outlined in the PEA.”

In terms of progressing work on long-lead time items, Roxgold said it had awarded the plant site bulk earthworks tender, with a contract expected to be executed and works commenced in the June quarter to support the project critical path.

The company has continued to advance its early works program at site including upgrading of the site access road and construction of the accommodation village. Contracts were awarded for camp bulk earthworks and camp construction, with first concrete poured last month, it said.

Surveying has been completed for the 33 kV and 90 kV power lines to tie into the existing 90 kV transmission line running across the property, which is connected to the 225 kV ring main system around the country. These early work activities will enable a rapid ramp up to full construction upon completion of the feasibility study and mine financing in the June quarter of this year.

Roxgold says it has undertaken a competitive tender process and has conducted a detailed assessment of the contract mining proposals received. It is currently completing diligence on the shortlisted parties and plans to award the mining contract later this year to allow for contractor mobilisation, site establishment,and commencement of pre-production mining early next year.

John Dorward, President and Chief Executive Officer, said: “The Séguéla project has rapidly become a cornerstone asset for Roxgold, and we believe that the project will provide significant value to all our stakeholders.

“The feasibility study is on track to be announced in the second (June) quarter, which we believe will demonstrate the ongoing evolution of the Séguéla PEA with an enhanced mine life and project economics with the inclusion of the high-grade Koula deposit into the mine plan.”

Hycroft Mining continues evaluation of novel sulphide heap oxidation/leach process

After testing out a “novel” oxidation and leaching process at the Hycroft Mine in Nevada, USA, Hycroft Mining Holding Corp is making plans to go back to a conventional oxide leaching setup in 2021.

The company produced 27,392 oz of gold and 178,836 oz of silver in 2020, an almost three-fold increase over 2019. It hit these numbers while operating at a pre-commercial scale using the novel process, which oxidises sulphides ahead of leaching.

It is now planning for run-of-mine production of 45,000-55,000 oz of gold and 400,000-450,000 oz of silver in 2021 using conventional cyanide heap leach.

It is anticipated that mining in the first four months of 2021 will be performed using the existing Hycroft fleet and a rental fleet, moving approximately 1.5 Mt/mth of ore and waste. For the remainder of the year, Hycroft intends to mine some 500,000 t of oxide and transitional ore and waste per month with a more cost-effective mining fleet.

Diane R Garrett, President & Chief Executive Officer, reflected on the results: “2020 was an important year for Hycroft as the company continued to focus on the restart of the Hycroft Mine. Throughout the year, we advanced work on the proprietary two-stage sulphide heap oxidation and leach process and made several important findings that will need to be addressed prior to our implementing the novel technology on a commercial scale.

“In 2021, we expect to mine predominantly oxide and transition material, which are more economic when treated using a conventional run-of-mine heap leaching method, which gives us the opportunity to continue to refine the operating parameters and flowsheet for the new heap leach pad and novel process. While the company continued to make significant progress in better understanding this proprietary process and its application on a commercial scale, the past year also presented some operational challenges, including learning to navigate in a newly emerged COVID-19 world.”

In the last few months, Hycroft says it has worked alongside consultants to identify and investigate opportunities for improvements in operating parameters for the two-stage sulphide heap oxidisation and leach process. The result of the work to date has identified several items that were not considered or included in the original plan and design but are critical to the success of this process. These findings include:

  • Adding a forced air injection system for the leach pad which is a key component of the oxidation process;
  • Developing a system for segregating solution flows to and from the heap leach pad to avoid co-mingling of solutions among heap lifts and ore processing stages that negatively impact recoveries and conditions on the leach pads;
  • Identifying that the finer crushed material requires agglomeration in order to achieve optimal permeability and gold/silver recoveries;
  • Understanding that higher soda ash, caustic soda, and cyanide consumption will be required which Hycroft experienced throughout the 2020 pre-commercial test pad programs and recently confirmed through the review of the test work;
  • Determining that some transitional ores are more economically attractive when processed as direct leach, run-of-mine material; and
  • Concluding that additional variability metallurgical and mineralogy studies will be required to better understand each of the geometallurgical domains in the orebody. While there was some variability work completed in the past, the recent test work has revealed that additional variability test work and compositing is necessary to fully understand the geometallurgy of each domain, and that additional sampling, including sampling below the water table where the predominance of the sulphide resources exist, is required given the complexity and variability of the large orebody.

The additional variability test work will also include detailed mineralogy studies as it is important to understand the role other minerals may play in the overall oxidation process and to enhance Hycroft’s ability to measure oxidation rates accurately and consistently, it said.

The team at Hycroft has developed an approximate $10 million program for drilling and additional metallurgical and mineralogical studies in 2021. This program of work has been approved by the Board of Directors of Hycroft and can be funded from existing cash and Hycroft’s current operating plans.

Hycroft expects to mine and stockpile at least 300,000 tons (272,155 t) of sulphide ore in 2021 that, once sufficient additional work on the novel process has been completed, will be available for testing to further refine operating parameters and measure its performance for large scale application of the oxidation heap leach.

Garrett added: “2021 is a foundational year designed to advance the work necessary in preparation for larger-scale sulphide operations. The team is working diligently to optimise current and future heap leach mine plans and to evaluate all opportunities for more profitable mine plans in the near and medium term. This work involves taking a ‘ground up’ approach working from the orebody out. The company’s prior plan was developed using a $1,200/oz gold price pit shell which leaves profitable ore behind in the current gold and silver price environment. By running pit shells at recent gold and silver prices, we have identified additional areas of oxide mineralisation that can generate cash flows over the next several years and we have already begun to identify areas of higher-grade mineralisation that will become important for mine sequencing and further improving cash flows prior to accessing sulphide material.”

As the company considers life-of-mine development and planning for the Hycroft deposit, particularly in the current gold and silver price environment, Hycroft says it is prudent to evaluate proven processing technologies for treating some ore types that may be more profitable than only using the two-stage sulphide heap oxidation and leaching process.

Potential opportunities being examined by the company in 2021 include: developing an understanding of the grade range distribution of the sulphide material; completing on-going work on the higher-grade areas of Hycroft; and following up on historical high-grade intercepts.

In order to capitalise on these potential opportunities, which take advantage of the current commodity price environment, Hycroft believes that it should also evaluate the benefits of a multi-process operation. Long-term operating scenarios may include conventional run-of-mine cyanide heap leaching for the oxide and transitional material, sulphide heap oxidation and leaching using the novel process, and an appropriately sized milling and flotation plant for processing the higher-grade ranges of sulphide material.

“The company believes that the plan it has put in place for 2021 will provide the new team the time to fully consider and evaluate these opportunities and make any necessary changes to improve the leach pads, process plants and process flowsheet, maintain and develop its workforce, and advance the project, in order to further enhance the value of the project,” it said. “As the test work advances and alternative processes are considered, the company expects to perform technical studies and trade-off evaluations which may result in an updated feasibility study.”