Tag Archives: Ghana

Automation, electrification, alternative haulage weighed for GSR’s Wassa UG expansion

A preliminary economic assessment (PEA) on the potential expansion of Golden Star Resources’ Wassa gold mine in Ghana has flagged the potential for applying alternative underground haulage methods, and autonomous and battery-electric equipment at the operation.

The PEA provides an assessment of the development of the Southern Extension of Wassa and the increase in mining rates to fully use available process plant capacity. While the study itself represents a conservative plan that excludes exploration opportunities from the scope and adopts the current mining practices and equipment, the “opportunities” section of the technical report outlines some more innovative approaches to expanding mining rates and filling the plant capacity.

Wassa, which Golden Star owns 90% of, produced 168,000 oz of gold in 2020 using the sub-level longhole open stoping method.

The PEA is focused on the development of the large inferred mineral resource (just over 7 Moz) which comprises the Southern Extension zone. Around 50% of the total resource was included in the PEA inventory, which showed off a life of mine of 11 years, with total gold production of 3.5 Moz. Average annual gold production of 294,000 oz represented an approximate 75% increase on the current production rate.

The mine plan considers a production rate targeting the processing capacity, at or close to 2.7 Mt/y run-of-mine material, after a five-year ramp-up period. The plant has previously operated at these rates with feed from both Wassa and the Bogoso-Prestea operation (since sold).

Mining would be by underground trackless decline access (1:7 gradient), with access from duplicate access ramps and independent ventilation infrastructure on each side of the deposit to support the increased mining rate and provide efficient access across the mineralised footprint (circa-850 m along circa-300 m across strike). Truck haulage will utilise the dual access ramps.

The mining method proposed for the expansion is bottom-up long hole open stoping with 25 m level spacing and nominal stope sizes of 25 m length x 30 m width x 25-100 m height with cemented paste backfill. Stopes will be mined in a primary-secondary sequence down to around 1,000 m depth, transitioning to pillarless retreat below that point to account for increasing in-situ stress, which will need to be further investigated in future work.

The PEA assumes average recovery of 94.8%, which is supported by current plant performance and metallurgical test work on a small number of samples that suggest processing performance for the Southern Extension feed will be similar to material currently treated. This will be evaluated in the next phase of work.

Capital expenditure is expected to total around $790 million over the life of the PEA mine plan. Of this total, 29% is growth capital and 71% is sustaining capital. The PEA mining method relies on paste fill, with Golden Star confirming the paste fill plant was constructed in 2020 and commissioning is expected to be finalised this quarter. Capital has been allowed for an expansion of the paste fill system in the PEA mine plan.

Based on a $1,300/oz gold price, the expansion project is expected to generate a post-tax net present value (5% discount) of $452.2 million.

So far, so conventional…

The company said it planned to complete option and trade-off studies to optimise the project plan ahead of a feasibility study on the expansion, due in early 2023.

Just some of the innovations being considered in these trade-off studies include the use of automation, electrification and alternative haulage.

In terms of increasing machine productivity through technology, the study listed off the potential use of semi- or fully-autonomous vehicles to increase shift operating time and remove operators from hazardous areas. It said the highest likelihood applications were in production drilling and drawpoint loading.

Golden Star confirmed current projects included in its in-development technology roadmap were the introduction of tele-remote loading and digitalisation of production data.

In terms of haulage infrastructure opportunities, Golden Star said it was considering the replacement of truck haulage with an infrastructure system like shaft hoisting, conveyor, or Rail-Veyor. The capital demand for such options would be offset by a large reduction in operating costs with automated systems, reduced diesel consumption and reduced ventilation demand, it noted.

These haulage options were being studied to design different systems, estimate capital and operating costs, then complete a trade-off analysis, the company said.

The current mine design assumes loaders digging from open passes to load trucks, but Golden Star said feeder systems could be installed to automate loading, increasing efficiency and reducing operating costs.

And, of course, the company said it was considering options for clean energy technology applications, particularly battery-electric trucks. As part of this, it was assessing available systems and developing fleet selection criteria. This will have knock-on benefits to the mine’s ventilation requirements.

Gold Fields installs CAS safety solution at Tarkwa gold mine

Gold Fields is upping the safety stakes at its Tarkwa gold mine in Ghana, employing a collision avoidance system (CAS) that should reduce the number of vehicle-to-vehicle and vehicle-to-personnel interactions at the open-pit operation.

Having installed a fatigue management system back in 2012-2013 – which saw equipment interactions and accidents decrease – the company has now purchased the HxGN MineProtect Collision Avoidance System Pro as part of a “discrete, dedicated project”, a company spokesperson confirmed to IM.

Hexagon says the CAS Pro system protects all mining vehicles, assets and vehicle operators within 500 m of the installed cab-based unit in open-pit mines.

The solution provides 360° awareness for surrounding vehicles and selected assets, as well as a collision avoidance function based on path prediction, the company explained.

Using GNSS and RF technologies, the solution enjoys high operator adoption because of minimal nuisance alarms and enhanced safety for all mine and vehicle types, according to Hexagon.

The Gold Fields spokesperson said CAS Pro was being used in line with Earth Moving Equipment Safety Roundtable (EMESRT) guidelines. The solution includes operator awareness and advisory controls, the spokesperson added.

As part of the project, Gold Fields has issued 150 personal tags to employees working near operating equipment, including spotters and samplers. The operating equipment to benefit from the new solution includes 84 dump trucks, 21 excavators, 65 pieces of ancillary fleet (including loaders, dozers and service trucks) and 100 light vehicles (50 with fixed CAS units and 50 with removable units).

While the CAS solution does not include anti-braking functionality, it does have a range of other intervention procedures, according to the spokesperson.

“Stopping a plus-200 t haul truck in milliseconds in an open-pit environment may create other hazards,” the spokesperson explained.

Gold Fields to trial Caterpillar dual-fuel solution on haul trucks at Tarkwa mine

Gold Fields plans to test the use of LNG to power haul trucks in a trial at its Tarkwa open-pit gold mine in Ghana, CEO Nick Holland told attendees of the IMARC Online event this week.

Speaking on a panel reviewing progress of the Innovation for Cleaner, Safer Vehicles (ICSV) initiative – a supply chain collaboration between the International Council on Mining and Metals (ICMM) and original equipment manufacturers (OEMs) – Holland said the trial would involve a mix of LNG and diesel fuel at the operation, and four trucks would initially be tested with the fuel combination in 2021.

Gold Fields later confirmed to IM that the trial would take place in the second half of 2021 and involve the use of Caterpillar’s dual-fuel LNG Dynamic Gas Blending (DGB) retrofit system on four of the mine’s Cat 785C 146 t payload dump trucks.

The DGB conversion kits, available on Cat 785C and 793D haul trucks, are a dual-fuel technology that enables miners to substitute diesel fuel with LNG, according to Cat. The use of LNG has been proven to reduce emissions by up to 30%, as well as lower costs by up to 30%, Cat says.

DGB vaporises liquid fuel into natural gas, then replaces diesel fuel with LNG when possible. On average, DGB replaces about 60-65% of diesel with LNG, according to Cat.

Tarkwa, which is 90% owned by Gold Fields, produced 519,000 oz of gold in 2019, 1% lower than the 525,000 oz produced in 2018. It employs Engineers & Planners Co Ltd as mining contractor.

While this trial will potentially lower the company’s carbon emissions – as will Gold Fields’ plan to fit “diesel filters” on all its machines underground in the next 12-18 months – Holland pointed to a much loftier long-term goal during the ICSV panel.

“The challenge to our teams and OEMs is to move away from diesel completely,” he said.

Such a move could see the company employ both battery-powered and hydrogen-powered solutions at its underground mines, he added.

Obuasi gold mine becomes ‘modern, mechanised mining operation’

The renowned Obuasi gold mine, in Ghana, is back in action with AngloGold Ashanti confirming the redeveloped asset has poured first gold, five years since mining activities were suspended.

This achievement signals the successful redevelopment of the mine into a “modern, mechanised mining operation”, the company said.

The Obuasi Redevelopment project, which seeks to access Obuasi’s 30 Moz orebody over the next two decades and beyond, has completed the first phase of construction on time and on budget. Refurbishment of an existing plant and construction of new infrastructure and underground development, in line with a new mine plan, has taken place over the last 18 months.

AngloGold Ashanti Chief Executive Officer, Kelvin Dushnisky, said producing first gold on budget and on a tight schedule was a “significant achievement” for the company, the community of Obuasi and Ghana as a whole.

“Restarting this important mine is testament to the focused execution by our team on the ground, as well as the clear investment framework and supportive environment created by the President of Ghana and his government, and the King of Ashanti,” he said.

Following a ramp-up period, AngloGold Ashanti estimates mining at a rate of 2,000 t/d from Obuasi during 2020, climbing to 4,000 t/d by year-end. The mine will be producing gold at an average run-rate of 350,000-400,000 oz/y for the first 10 years, and above 400,000 oz over the life of mine at all-in sustaining costs of around $800/oz, according to the company.

Graham Ehm, AngloGold Ashanti’s Executive Vice President of Group Planning and Technical, who is overseeing the project, said: “The team has done an excellent job completing the first phase of this project and will be focused on ramping up production through next year.

“The difficult decision was made to suspend production in 2014 to rebuild the mine’s foundation for a sustainable long-term future that will bring benefit to the region over the coming decades. We are tremendously proud of what has been achieved since then.”

The underground mine development is ongoing, with deepening of the Obuasi Deeps Decline and access to the KRS shaft on schedule for mid-2020. The construction of new plant and infrastructure will continue in 2020. The initial project capital for Obuasi remains in the range of $495-$545 million, spent between 2018 to the end of 2020.

AngloGold Ashanti says it is working closely with government and community stakeholders to ensure that the Obuasi mine is developed sustainably, fuelling growth for Ghana and benefitting the communities around the mine. A committee, including local stakeholders and regulators, has been created to track execution of the reclamation of the mine site and the mine will also be contributing $2/oz of gold produced to a Community Trust Fund, over its life, to facilitate development projects in the local area.

Some 80% of the capital thus far has been spent in-country, according to the Managing Director of the Obuasi Mine, Eric Asubonteng. “Ghanaian companies have been given preference in the procurement of goods and services, from the large-value underground mining contract all the way to catering and security contracts,” the company said.

Employment has also prioritised Ghanaians from the immediate area around the mine wherever possible, with Ghanaians from elsewhere in the country next in line for recruitment in available roles.

Newmont Goldcorp delivers the hat-trick with Ahafo mill expansion

Newmont Goldcorp has announced that the Ahafo mill expansion in Ghana achieved commercial production, on schedule and within budget for around $175 million.

Combined with the Subika Underground operation, which was successfully completed in November 2018, the mill expansion is expected to increase Ahafo’s average annual gold production to between 550,000-650,000 oz/y through 2024, while lowering life-of-mine processing costs.

“The Ahafo mill expansion represents our third profitable project delivered on schedule and within budget in 2019, along with the Tanami power project in Australia and the Borden mine in Canada,” said Tom Palmer, President and Chief Executive Officer. “The mill expansion is expected to generate an internal rate of return of more than 20% at a $1,200 gold price, while also extending profitable production at Ahafo through at least 2029.”

Features and benefits of the mill expansion include:

  • Increasing mill capacity at Ahafo by more than 50% to nearly 10 Mt/y with the addition of a crusher, grinding mill and leach tanks to the circuit;
  • Adding annual gold production of 75,000 to 100,000 oz/y for the first five full years beginning in 2020;
  • Accelerating efficient processing of ore from stockpiles and the Subika underground mine, as well as harder, lower-grade ore from Ahafo’s existing pits; and
  • Supporting profitable development of Ahafo’s highly prospective underground resources, which continue to demonstrate considerable upside.

Ahafo is expected to deliver record production this year – with improved costs – driven by higher grades from the Subika open pit, a full year of mining from the Subika underground mine and the completion of the Ahafo mill expansion.

Commercial production began at Ahafo in 2006, and, in 2018, the operation sold 436,000 oz of gold at all-in sustaining costs of $864 per ounce.

New WEG VSDs to help ventilate underground gold mine in Ghana

Two units of the newly developed WEG 11 kV Variable Speed Drive (VSD) have been commissioned at an underground gold mine in Ghana by WEG Automation Africa, a member of the Zest WEG Group, the company says.

According to Kirk Moss, Senior Manager: Projects and Engineering at WEG Automation Africa, the new WEG MVW3000 VSD is a valuable addition to its medium voltage VSD portfolio, and brings a range of benefits to customers.

“It gives WEG Automation Africa even greater flexibility in our market offering, further enhancing our capability to provide customised solutions,” he said.

The first two 11 kV units produced are for 850 kW ventilation fan motors in the underground gold mine in Ghana, according to the company.

The design is based on the cascaded H-bridge topology, using multiple low voltage power cells in combination to achieve the desired voltage output, the company said. The input switch, phase-shifting transformer and VSD are fully integrated in a single MV panel.

Moss said: “The WEG MVW3000 is particularly suited to applications where there are standard motors with no special insulation or where existing motors are being modified for VSD control.”

This VSD delivers high quality input power using low harmonic multi-pulse transformers. Users benefit from a high efficiency of over 96.5% throughout the entire load range, and a power factor of more than 0.95 throughout the entire speed range, according to the company.

“The design includes power cells with long-life plastic capacitors, which are more reliable and last longer than dry type capacitors,” Moss says. “They also have the advantage of not needing to be reformed after long periods of storage.”

In standard configuration, the 11 kV VSD is available from 40 A to 400 A – or 640 kW to 6,500 kW – although larger sizes are also available if required, the company said.

Among the options on the WEG MVW3000 is an automatic cell bypass solution. This ensures minimal reduction in the output-rated torque so normal operations can continue. Redundant power cells can also be added to the design to ensure 100% torque can be maintained.

Prior to delivery, all VSDs are fully load-tested in WEG’s facility in Brazil.

Newmont Goldcorp Ahafo expansion project produces first ore

Newmont Goldcorp says the Ahafo Mill Expansion (AME) project in Ghana has successfully processed its first ore and is on track to achieve commercial production in the December quarter of 2019.

The mill expansion will increase average annual gold production at the Ahafo mine by between 75,000-100,000 oz for the first five years, beginning in 2020, with mill capacity expanding by more than 50% through the addition of a crusher, grinding mill and leach tanks. It is expected to deliver an internal rate of return of more than 20% and, together with other projects at Ahafo, extend profitable production through at least 2029.

Tom Palmer, President of Newmont Goldcorp, said: “Combined with Subika Underground, which was successfully completed in November 2018, the mill expansion will increase Ahafo’s production to between 550,000 and 650,000 oz per year through 2024, while lowering life-of-mine processing costs.

“The project also accelerates the efficient processing of stockpiled ore and supports profitable development of Ahafo’s highly prospective underground resources, which continue to demonstrate considerable upside.”

In 2019, Ahafo is expected to achieve record production – with improved costs – driven by higher grades from the Subika open pit, a full year of mining from the Subika Underground and the completion of the AME. Capital costs for the AME are estimated at between $140-180 million. Commercial production began at Ahafo in 2006 and, in 2018, the operation sold 436,000 oz of gold at all-in sustaining costs of $864/oz.

Over the last six years, Newmont has successfully built 11 new mines, expansions and projects on four continents – on or ahead of schedule and at or below budget. These projects include Akyem and the Phoenix Copper Leach in 2013, the Turf Vent Shaft in 2015, Merian and Long Canyon in 2016, the Tanami Expansion in 2017, and Twin Underground, Northwest Exodus and Subika Underground in 2018, and the Tanami power project in 2019. The company also completed a value-accretive acquisition of Cripple Creek and Victor in 2015 and delivered a profitable expansion at the mine in 2016.

GeoDrill backs IronRidge Africa exploration plan with ‘drilling for equity program’

IronRidge Resources has entered a binding memorandum of understanding (MoU) with GeoDrill as part of a “drilling for equity program” of up to $4 million, or 40,000m of drilling at the exploration company’s gold and lithium portfolio throughout Africa.

GeoDrill, established in 1998, is a leading exploration drilling company with a fleet of 67 drill rigs that has operations is Ghana, Burkina Faso, Côte d’Ivoire, Mali, and Zambia.

The MoU will see IronRidge advance all projects across Ghana, Côte d’Ivoire and Chad, while maintaining cash resources, it said.

IronRidge’s Chief Executive Officer, Vincent Mascolo, said: “We are delighted to announce that the agreement with GeoDrill secures access to expert drilling capabilities, which will allow the company to effectively advance its portfolios, whilst helping preserve cash resources.

GeoDrill brings decades of operational expertise throughout West Africa and, with operational centres in both Ghana and Côte d’Ivoire, provides excellent synergies with the Ccmpany’s current jurisdictions of focus.”

Dave Harper, Chief Executive Officer of GeoDrill, said: “Having previously worked with IronRidge on their Cape Coast lithium project and Côte d’Ivoire gold projects, we understand their exploration business model and it was an easy decision for us to partner with IronRidge in this drilling for equity program.”

Under the terms of the binding MoU, any drilling services provided by GeoDrill will be paid by either; cash, shares, or a combination of cash and shares on a 50/50 basis at IronRidge’s election.

The agreement is based on a competitive quotation process, which provides for the issue of ordinary shares in IronRidge for 50% of the drilling cost up to a value of $4 million in two $2 million stages.

“The agreed payment mechanism comprises a share valuation of 90% of the 15-day volume weighted average price against the value of each monthly invoice,” IronRidge said.

Geodrill has commenced drilling works in Ghana where approximately 13,200 m of drilling has been planned at the Cape Coast lithium project over a staged reverse circulation and diamond drilling program dependent on results. It is also currently continuing field mapping and sampling programs over the Zaranou gold project, in Côte d’Ivoire, ahead of a planned air-core drill program.

In Côte d’Ivoire, IronRidge is assessing air-core results over its Bianouan and Bodite licences to determine the next steps as well as soils and trenching results over its Kineta and Marahui licences.

“At this stage the company will maintain its focus on the Côte d’Ivoire gold portfolio and the Ghana lithium portfolio,” IronRidge said.

Newmont Goldcorp sees value in expanding process control support hub

Newmont Goldcorp says it plans on expanding its Process Control Operations Support Hub globally following a successful pilot project launched in Australia, in 2018.

The company will start the expansion in Ghana, where its Ahafo, Akyem and Subika mines reside, but expects full implementation in 2020, it said.

The Process Control Operations Support Hub pilot project was launched in 2018 with a mandate to streamline process control systems, procedures and monitoring tools, the company said.

“Thanks to the teamwork and collaboration of our Boddington team, the pilot project was a great success, demonstrating the need for process control support and the value of the project’s innovations,” the company explained. “We learned that the operational support hub model accelerates the advanced process control value at our sites and allows for knowledge and expertise to be targeted in a cost-efficient way.”

The company also found that the demand for operations support hubs was higher than expected, and that introducing this support model would help drive improvement at its sites.

In line with the company’s Full Potential program’s mandate to identify opportunities for efficiency and innovation across our business, the support hub has added $2.8 million in what the company calls “Full Potential value” to date, Newmont Goldcorp said.

Boart Longyear hits record drill depth at Ghana gold project

Boart Longyear’s drilling crews have drilled the deepest hole ever drilled in Ghana, according to the Salt Lake City-headquartered company.

They drilled a hole 2,083.4 m (6,835 ft) deep, having installing a wedge and navi to drill the hole on track at 600 m and keeping it on track to the end of the hole. The directional drilling project for one of Golden Star Resources’ gold projects was completed safely and ahead of schedule, the company said.

Division Manager, West Africa, Jonathan Madigan, said: “Our drilling crew in Ghana on this project worked safely and diligently in directionally drilling the hole to the target depth. I couldn’t be more proud of the team that completed the project.

“Boart Longyear’s consistent hazard and risk-focused safety culture is embraced by the crews here in Ghana and they appreciate that the field level risk assessments, pre-shift meetings and other safety programs are designed to get them home safe to their families.”

Boart said: “The company has received client recognition for their safe, on-target, and ahead of schedule completion of the deep coring exploration drilling project. Boart Longyear acknowledges the participation, collaboration, and contributions from every employee within Ghana and especially the drilling crew that worked directly on this record-depth hole.”