Tag Archives: Silver

Northern Vertex Mining ready for more gold at Moss mine

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Production looks like increasing at Northern Vertex Mining’s recently started up Moss gold-silver mine, in Arizona, USA, as recent modifications to the Merrill Crowe facility and additional output from the heap leach kick in.

The company produced 7,482 oz of gold and 45,876 oz of silver during the three months to the end of June, compared with 6,057 oz of gold and 25,558 oz of silver, marking the company’s strongest quarter to date. In June, alone, Northern Vertex saw 2,580 oz of gold and 18,051 oz of silver come out of the operation.

The Moss open pit and heap leach gold and silver mine hit its commercial straps in September 2018, at which point the company said expected fiscal 2019 production guidance was 36,000-40,000 oz of gold equivalent production.

Northern Vertex said this week that its operations team has made progress in correcting issues that have hampered the process plant since started up, with modifications to the filter press piping, clarifiers and vacuum pump system nearing completion.

“We have observed a large decrease in reagent consumption and an immediate improvement in recoveries of gold and silver from the pregnant solutions,” the company said.

Such improvements to the Merrill Crowe facility recently resulted in the company’s single largest gold shipment to date – of $1.2 million representing nine days of production.

The Moss team initiated a recovery study of the heap leach pad in May 2019, with the purpose to confirm consistent moisture percolation throughout the pad; measure solution volume and solution grade retained in various areas (panels) of the pad, in order to determine the gold and silver inventory remaining on the pad; obtain samples for further bottle roll testing, in order to estimate the amount of gold inventory that can be recovered by re-leach; and design and implement a leach solution application plan to recover additional gold from the leach pad inventory.

Results from the first panel (known as the ‘Central Panel’), which contains approximately 235,000 t of ore have been received, the company said. “Results show remarkable consistency in the percolation of solution, both laterally and vertically. Furthermore, the study confirms there are no dry areas, channelling is not occurring, the pad is retaining its moisture as expected and that the recoverable gold and silver in inventory will meet or exceed feasibility predicted recoveries.”

While the full study, which will include an additional five panels is ongoing, Jim Gubler, Process Manager at Northern Vertex, said the results from the Central Panel indicated there are around 5,000 oz of recoverable gold contained in this area, of which an “estimated 3,000 oz have already been dissolved in the water held in the heap and need only to be flushed and collected”.

He added: “With the leach solution application plan that we have designed, we are projecting that a significant portion of this gold will be recovered over the next several months, which should add to our normal monthly production.”

The ongoing column test program (using crushed ore samples) is predicting ultimate recoveries of approximately 80% for gold and 60% for silver from the heap leach. The column test work on the crusher samples and the heap leach pad recovery study described above will also be used to optimise and shorten the recovery curves going forward, using live ore panels for testing rather than bulk samples that were used in the feasibility, Northern Vertex said.

“Every current test being run indicates that we should be able to outperform the feasibility recovery curves,” the company concluded.

Tenova DELKOR shows off sedimentation specialism at Morocco silver project

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Tenova DELKOR says it has successfully supplied and carried out mechanical completion of seven DELKOR thickeners, together with its flocculation system and a DELKOR Pinned Bed Clarifier (PBC) for a silver leaching plant project in Morocco.

The thickeners are to be employed in the counter current decantation circuit of the plant, with the project including the design, fabrication and supply of thickeners, flocculation plant and PBC, supervision of installation and performance guarantee.

The PBC is a unique process for hydrometallurgical plants where solution clarity is important, according to the company. “A technology for polishing feed solutions for solvent-extraction plants, the unit offers low suspended solids counts in overflows, regularly achieving clarities of less than 50 ppm solids, and as low as 20 ppm.”

Benefits of the PBC technology, according to Tenova DELKOR, include low capital expenditure for comparative clarifying technology; no moving parts, virtually eliminating the need for maintenance; robust and stable performance; it is optimised to minimise flocculant consumption, and; a small footprint.

Ramesh Mahadevan, DELKOR India Managing Director, said: “As the industry specialist in sedimentation, DELKOR offers a range of thickeners and clarifiers catering to various applications across the minerals, chemical, industrial and water management industries with designs of up to 100 m in diameter.

“Successful hand over of this important project only serves to strengthen our capabilities in the North African region and is a true testament that.”

CRC ORE grade engineering trial pays off for Minera San Cristóbal

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A successful full-scale production trial of Australia-developed grade engineering techniques is paying dividends for a South American mine, and its local workers, according to CRC ORE.

Once fully implemented, this is expected to generate an additional A$451 million ($312 million) in profit for the mine and reduce its energy consumption, it said.

Located in the south-western Bolivian province of Nor Lípez, and owned by Sumitomo, Minera San Cristóbal (MSC) is the country’s largest mine. Operating since 2007, the mine produces around 1,500 t/d of zinc-silver and lead-silver concentrates. To achieve this result, MSC needs to move a daily average of 150,000 t of rock – ore and waste.

Part of MSC’s vision is to “develop a model mining operation through safe operations, at low cost, with innovative technology”.

Through its wholly-owned subsidiary, Summit Mining International, Sumitomo is a participant of the Cooperative Research Centre for Optimising Resource Extraction (CRC ORE). Based in Brisbane, Australia, CRC ORE works to minimise the impact of declining grades and radically improve the productivity, energy and water signatures of mining operations, CRC ORE said.

The centre is jointly funded by what it calls ‘Essential Participants’, which includes mining companies such as Sumitomo; mining equipment, technology and services (METS) companies; research organisations; and the Australia Government.

One of CRC ORE’s key solutions developed for the mining industry is grade engineering. “This solution deploys a range of waste rejection technologies that integrate with a suite of separation technologies relevant to ore specific characteristics,” CRC ORE said. “A deeper understanding of the orebody can be achieved, leading to the ability to exploit inherent ore deposit heterogeneity and variability.”

For mining operations such as MSC, this involves an innovative approach to the early separation of ore from waste material, minimising the impact of declining grades and productivity.

CRC ORE and MSC teams conducted site studies and analysis in 2017 to determine the level of opportunity available at the mine by deploying grade engineering, and a great deal of potential was evident.

Since late 2018, CRC ORE and Sumitomo have been working together on a full-scale production trial of grade engineering using screening at MSC. A Metso Lokotrack ST2.8 mobile screening plant, which can process up to 450 t/h, was deployed on site to assist in providing a production-scale testing capability.

The trial focused on upgrading mineralised waste from the pit to determine if grade engineering could efficiently produce a new economic stream of valuable material that could then be combined with run of mine feed through to the concentrator and produce a positive net smelter return.

CRC ORE Chief Executive Officer, Ben Adair, said initial results of the trial were impressive and encouraging, with 66% of value now contained in just 25% of the grade engineered mass.

“So far, results show that by applying grade engineering to areas previously designated as ‘mineralised waste’, the value of grade engineered feed to the mill can be increased by over 2.5 times,” Adair said.

“This has the potential to convert this waste material into high-grade ore feed with associated opportunity to increase metal production and reduce process power and water intensities.”

A 15-20% reduction in energy has been evident in the mine’s SAG mill when processing a combined grade engineered and direct run-of-mine feed, according to CRC ORE.

The success of the grade engineering trial has led to Sumitomo considering deployment of grade engineering techniques for life of mine extensions, CRC ORE said.

MSC Operations Director, Dave King, said: “The big benefit of grade engineering is its potential ability to extend the life of the mine and add over A$451 million in profit to its value.”

To fulfil its goals of knowledge transfer and for its technology to directly benefit the local mining industry, CRC ORE says it has recently commenced similar production trials at Australia mining operations.

GoGold signs up BQE Water for SART plant at Parral tailings operation

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BQE Water says it has been retained by GoGold Resources for the implementation of a sulphidisation, acidification, recycling and thickening (SART) plant at the Parral operation in Chihuahua, Mexico.

The contract comes after on-site testing and preliminary assessment of SART integration into the metallurgical process at Parral that were completed earlier by BQE Water.

Under the contract, BQE Water’s scope of work will include plant engineering design, process automation, engineering support during procurement and construction, plant commissioning, and ongoing operations support after plant start-up. The plant construction is expected to be completed by the end of the year. Once the plant is commissioned, BQE Water will provide operations support services for a monthly fee for a period of three years, it said.

Owned and operated by GoGold Resources, the Parral project involves the reprocessing of old tailings to recover silver and gold by conventional cyanidation. In addition to the precious metals, the tailings also contain significant quantities of cyanide soluble copper and zinc. These base metals compete for cyanide, causing high cyanide consumption and increasing operating costs, according to BQE.

Anis Nehme, COO of GoGold Resources, said: “We have been working with BQE Water for the past few years to evaluate SART integration into the Parral project and we are relying on their expertise to help us maximise the positive contribution SART can bring to the project’s overall performance.”

David Kratochvil, President & CEO of BQE Water, said: “This contract is further proof of our leadership in the safe, cost-effective and rapid deployment of SART to help precious metals producers improve the metallurgical and environmental performance of their projects.

“We stand behind our proven process designs perfected over multiple large projects completed in the past decade and in our operations support capabilities to ensure SART benefits are maximised while operational risks are minimised.”

The SART process recovers copper from cyanide leach solution while allowing free cyanide to be recycled back to the leaching of precious metals. This lowers the cost of gold extraction and reduces the environmental footprint of gold mining projects, BQE says.

“SART can be a game changer that favourably shifts project economics and enables projects to move forward,” BQE said, adding that fewer than 10 industrial scale SART plants have been built and operated globally.

SolGold outlines new copper-gold-silver block cave mine plan at Alpala

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SolGold has laid out plans to develop a mine at its majority-owned Alpala copper-gold-silver deposit, in northern Ecuador, that will use block cave mining methods applied over several caves designed on two vertically extensive lifts.

The preliminary economic assessment on Alpala estimated a pre-production capital expenditure of $2.4-2.8 billion for a mine that could produce 150,000 t/y of copper, 245,000 oz/y of gold and 913,000 oz/y of silver in concentrate over the life of mine.

The PEA stated a post-tax net present value (8% discount) of $4.1-4.5 billion based on an average $3.30/lb ($7,275/t) copper price, $1,300/oz gold price and $16/oz silver price depending on a 40-60 Mt/y throughput rate.

As part of the PEA, four mine production cases were pre-selected and assessed. This included a 40 Mt/y option over a 66-year mine life, a 50 Mt/y blueprint with a staged ramp up and a 57-year life, a 50 Mt/y fast ramp-up plan with 55-year life and a 60 Mt/y route with 49-year life.

Unit C1 operating costs over the life of the mine were estimated at $0.90/lb copper after gold and silver credits using the 50 Mt/y, fast ramp-up plan.

Resources scheduled in the PEA block cave designs accounted for 2.4 Bt at 0.54% CuEq ROM grade.

SolGold said the prefeasibility study is expected to be completed in December 2019 with a definitive feasibility study scheduled for completion at the end of 2020.

SolGold CEO, Nick Mather, said: “The unusually low operating costs modelled are due to the relatively soft, fractured nature of the ore, resulting in enhanced caveability, a high degree of fragmentation in the cave and ease of crushing and millability, combined with low hydroelectric (consumption and unit) costs. The overall scale efficiencies also assist in the delivery of modelled low operating costs.”

Metallurgical work at Alpala, which is ongoing, indicates gold contents in the pyrite concentrate will require additional investigation to identify an efficient recovery strategy, SolGold said.

Additional metallurgical work is expected to identify solutions for recovery of gold and copper in the pyrite concentrate along with a sulphuric acid product.

Over the period to the end of 2019 when SolGold aims to complete the prefeasibility study, activities will focus on exploration, a new mineral resource, metallurgy and process design, investigation of further tailing disposal options and incorporation of further geotechnical and hydrogeological data into the PFS basis, SolGold said.

SolGold will also commence permitting and fiscal discussions with the Ecuador Government and financial discussions with third party financiers for SolGold’s share of the project costs following completion of the FS.

BacTech, GMR, Dundee Sustainable Technologies to revisit Snow Lake gold project

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BacTech Environmental, GMR and Dundee Sustainable Technologies are joining together to develop a potential solution for the remediation of the gold residual stockpile in Snow Lake, Manitoba.

As part of this effort, BacTech has signed a letter of intent with GMR to license its proprietary bioleach technology.

Through this agreement, BacTech received a C$20,000 ($14,689) cash payment as an advance on the right to use the bioleach technology on the project. In addition, BacTech will earn 3% undivided equity interest in the net income of the project.

This proprietary bacterial oxidation technology liberates precious and base metals from difficult-to-treat sulphide ores and concentrates, according to BacTech. This is a safe and environmentally-friendly process that has the advantage of improving metal recovery at significantly lower capital and operating costs when compared with traditional treatment methods of smelting, roasting and pressure oxidation, the company said.

BacTech said: “GMR is relying on BacTech’s historical research conducted in 2011-12 that showed oxidation rates of 95% and gold recovery of 88.6% on material obtained from the arsenic stock pile.”

It added: “Due to a lack of iron in the stockpile the residual material could not be stabilised and was abandoned.”

Ross Orr, CEO of BacTech, said: “Our return to Snow Lake is predicated on Dundee Sustainable Technologies providing a solution to the unstable arsenic product we generated in our earlier work that killed the project. The stockpile has a deficiency in iron leading to an unstable ferric arsenate product after bioleaching. By passing this unstable material to be vitrified, the arsenic can be safely disposed. We look forward to re-engaging in the Snow Lake project.”

David LeClaire, the CEO of GMR, said: “BacTech’s historic work on the project and its proprietary bioleach technology, teamed with DST’s vitrification technology, is a promising solution to the remediation of a longstanding environmental concern of the community of Snow Lake without cost to the taxpayer.”

The project consists of a stockpile of arsenopyrite concentrate proven to contain residual gold and silver. BacTech drilled and assayed the stockpile, which is currently the responsibility of the Government of Manitoba, in 2011 and produced a NI 43-101 report.

Current measured mineral resource estimates were generated in 2012 by BacTech estimating the Snow Lake concentrate stockpile contains 264,596 t grading 9.76 g/t Au and 2.17 g/t Ag. In addition, indicated resource estimates include 9,300 t grading 9.2 g/t Au and 2.15 g/t Ag, and an inferred mineral resource came in at 28,000 t at 7 g/t Au and 2.4 g/t Ag.

Europa mobilises diamond drill rig, service providers for Toral lead-zinc-silver exploration

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Europa Metals reports that a diamond drilling rig has been mobilised to its Toral lead-zinc-silver project in Leόn, northern Spain, as the London-listed company looks to commence a new exploration campaign in the next week.

The rig and associated operating crew is being supplied by Sondeos y Perforaciones Industriales de Bierzo SA and will be overseen by Europa’s on-site exploration team, the company said. The campaign will be conducted using a single drilling rig with assays sent for independent analysis on a rolling basis.

Addison Mining Services Limited (AMS) has been retained to carry out a revised independent resource update in accordance with JORC guidelines once the campaign has been concluded, Europa said, with Wardell Armstrong engaged to conduct the metallurgical test work from a representative sample taken from the drilling.

The core objectives of the drilling campaign are to drill into the high-grade core of the project, as defined within the existing inferred JORC resource (16 Mt at 7% zinc-equivalent); target high-grade areas within the defined resource to further the company’s understanding of the project – the aim being to increase confidence in the resource estimate and attain the indicated resource category – and; obtain a significant sample for the metallurgical test work to determine the potential zinc, lead and silver concentrate composition from Toral.

Laurence Read, Executive Director of Europa Metals, said: “Over the next two quarters, we are expecting to announce the results from the drilling, an updated JORC resource, and details of the likely product types that can be produced from Toral. Taken together, we believe that these key milestones will allow us to advance the processing design and commence discussions with potential offtakers.”

Canada Cobalt Works moves to protect Re-2OX process following SGS testing

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Canada Cobalt Works says it has made important breakthroughs in its proprietary and environmentally green Re-2OX process for the recovery of cobalt, precious metals and base metals, and will look to submit a patent application to protect the technology.

New testing using SGS Lakefield in Peterborough, Ontario, Canada, has highlighted further optimisation of Re-2OX can allow the recovery of silver and copper for the first time, while also increasing the recovery rates for cobalt and nickel.

“In refining the Re-2OX process through a one-step leach extraction, overseen by Canada Cobalt adviser Dr Ron Molnar, SGS has recovered >99% cobalt, >99% silver, 99% nickel and 99% copper while removing 99% of arsenic from a composite of gravity concentrates,” the company said.

The gravity concentrates tested at SGS were from the historic Castle mine, in Ontario, classified as waste material and grading 10.2% Co, 11,000 g/t Ag, 0.26% Cu, 1.49% Ni and 45.1% arsenic.

Re-2OX skips the normal smelting process to create battery-grade cobalt sulphate, according to Canada Cobalt Works. The company said nickel-manganese-cobalt (NMC) battery-grade formulations are also in the pipeline.

“In addition, the ability of Re-2OX to achieve exceptionally high recovery rates for both cobalt and silver, plus nickel and copper, while also removing 99% of arsenic, expands the potential of the Castle mine given Phase 1 underground results released February 19, 2019, and a second phase starting soon,” the company said. “Furthermore, Re-2OX is a value-driver for the company’s planned tailings programs at Castle and elsewhere in the district, and will also be used by Canada Cobalt to immediately build a new model of ‘streaming’ opportunities for the company with respect to other battery metal projects while protecting the process.”

Given the current optimisation level of Re-2OX, and the growing importance of this hydrometallurgical process to Canada Cobalt and its shareholders, the company has now initiated the process of submitting a patent application for this proprietary metal extraction method.

Frank J Basa, Canada Cobalt President and CEO, said: “The fact that SGS has demonstrated that Re-2OX can very efficiently recover a broad set of metals from arsenic-rich material, ranging from low grade to high grade, further de-risks the Castle mine project and expands opportunities to build shareholder value. Further Re-2OX optimisation will target the recovery of gold.”

Codelco looks to Uptake’s AI solution for equipment maintenance gains

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Uptake says it and the world’s largest copper producer, Codelco, are working on an artificial intelligence (AI) solution to monitor the health of mining equipment and ensure operations run efficiently and maintenance needs are predicted.

The agreement, part of Codelco’s digital transformation plan, includes mining and processing equipment at Codelco’s Division Ministro Hales (DMH) mine in Calama, Chile. In addition, Uptake will monitor grinding mills, roasters, crushers, pumps, haul trucks, and other machines with a view to creating a comprehensive and enterprise-wide Asset Performance Management solution across all of the company’s operating mines.

In 2017, the company’s DMH mine produced 215,086 t of copper alongside more than 126 t of silver.

Jaime Rivera, Codelco General Manager of the Andina Division, said: “Deploying artificial intelligence will allow Codelco to make best use of our operational data and allow us to reach our goals of boosting mining productivity, reduce costs and maintain safe machine operations through the predictive capabilities of Uptake’s Asset Performance Management (APM) software.”

Jay Allardyce, Uptake Executive Vice President of Industry, Product and Partnerships, said: “Codelco is the world’s leader in copper production and we’re pleased to support their digital efforts to make operations and maintenance expenditures more efficient by increasing visibility into the real-time and future health of mining machines.

“We are excited to partner with Codelco given their forward thinking to accelerate not only their operations, but the industry. With their data first approach coupled with our AI leadership, the transformation impact is outstanding and with leaders like Codelco it sets the tone for what is possible.”

Uptake’s APM software solution improves operational efficiency by leveraging AI to create business value from operational data, according to Uptake.

“Traditional asset management only covers routine maintenance tasks and fails to anticipate and adjust to the ways industry operates its business,” Uptake said. “Today’s asset-intensive environments require a new approach with industrial data science generating OEM (original equipment manufacturer)-agnostic insights, predictions and recommendations for any asset.”

By deploying Uptake APM, industry can unlock new operational efficiencies by making proactive maintenance decisions based on predictive insights, the company said. “Our industrial AI and machine-learning engines detect asset anomalies and help predict and prevent problems before they happen. Industry can also leverage the data analytics to understand how to drive more financial outcomes that impact business.”

Dundee Precious Metals reaches production milestone at Krumovgrad

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Dundee Precious Metals has achieved first gold concentrate production from its Krumovgrad open-pit gold mine, in Bulgaria, it says.

Following cold commissioning of the processing plant facilities, 650 t of ore was processed through the crushing, grinding and rougher flotation circuits at a rate of around 100 t/h, producing the first concentrate from the Ada Tepe deposit.

Rick Howes, President and CEO, Dundee Precious Metals, said: “With commercial production expected in the second (June) quarter of this year, this is the beginning of a new chapter for DPM, which will deliver significant growth in gold production and free cash flow.”

In the coming weeks, the focus will be on beginning the ramp-up and optimisation of the processing plant to achieve the design throughput of 105 t/h and the design gold recovery of 85%, according to the company.

The forecast capital cost for Krumovgrad remains at $164-$166 million, compared with the original estimate of $178 million. As at February 28, construction of the project was 97% complete with $147 million incurred.

Dundee said: “There is significant operating flexibility during ramp-up given the various grades of stockpiled mined ore at Krumovgrad.”

Gold contained in concentrate at Krumovgrad is expected to be between 55,000-75,000 oz in 2019, but, based on the mineral reserves for Krumovgrad, the mine will produce on average 100,000 oz/y of gold contained in concentrate for the first five years of production, with a life of mine average of some 85,000 oz at a $404/oz cash cost.