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Muckahi monorail-based tech removed from Torex’s Media Luna plans

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Torex Gold has decided to move forward with “conventional development and mining methods” for its planned Media Luna project in Mexico, following the outcome of various risk assessments, extensive comparative financial analyses, and the results to date of the Muckahi test program at El Limón Deep (ELD), the company said.

In the company’s June quarter results – which saw “solid operational performance” of 118,054 oz of gold produced, adjusted EBITDA of $122.1 million and generation of $21.9 million of free cash flow – Torex said the monorail-based technology would no longer be used in the Media Luna feasibility study currently being worked on and expected to be published in a technical report in the March quarter of 2022.

It explained: “After an analysis of the results to date of the Muckahi test program at ELD and an assessment of business risks, the board has approved a decision to pursue the Media Luna feasibility study on a conventional mining basis. While the monorail-based technology has progressed since the beginning of the ELD test program, testing to date of the individual components operating as an integrated system demonstrates that additional process and equipment engineering is required to achieve desired advance rates, cycle times, and associated cost efficiencies, and that there is insufficient available upside in using the technology as it relates to financial or schedule considerations for Media Luna.”

The use of the Muckahi technology, invented by former President and CEO Fred Stanford, would also leave the company with “no alternative readily available once the decision is taken to drive the two steep ramps at Media Luna, since there would be no access to the ore via any other method without considerable investment and schedule disruption associated with driving conventional ramps”.

Apart from the technical risks, there are additional business risks that require time and consideration such as permitting and regulatory compliance given there is no precedent for the technology, Torex added.

The company believes the use of a conventional mining process is a more prudent approach to mitigate operational and financial risk to the business given Media Luna will be its primary source of feed at the Morelos property after mid-2024.

It did leave the door open for use of the Muckahi technology in the future, saying aspects of the monorail-based technology were currently being deployed for development of the Guajes Tunnel.

“Management will consider including a preliminary economic assessment-level study to utilise monorail-based equipment to develop the smaller EPO deposit near Media Luna as part of the overall technical report to be released in Q1 (March quarter) 2022,” it said.

Potential deployment of the technology at EPO, which hosts an inferred resource of 1.01 Moz of gold-equivalent, would allow for additional testing of the integrated system within a live production environment.

The Muckahi system was engineered by MEDATech in close collaboration with Stanford.

The monorail mining system is billed as providing a surgical way to mine narrower orebodies more efficiently. It involves three logistical paradigm shifts: steep ramps (a quarter of the length of conventional ramps), roof-mounted monorails and equipment to run on them and minimal underground infrastructure.

The technology is expected to significantly reduce capital expenditure, operating expenditure and cut time-to-revenue by as much as 80%, according to Stanford. It will also produce 95% fewer underground greenhouse gas emissions.

The Muckahi technology was included in the Media Luna preliminary economic assessment, but the company always noted that it was experimental in nature and had not yet been tested in an operating mine.

When publishing its 2020 financial results in February 2021, Torex noted: “Since the date of the technical report, the majority of the components of the Muckahi system have been tested by Torex and their functionality demonstrated. Although, the components have not yet been tested together as a system to demonstrate the rates per day in which tunnels can be excavated and material removed from long hole open stopes.

“Testing of the integrated system will continue and is expected to be completed in the second (June) quarter of 2021. Drill and blast fundamentals, standards and best practices for underground hard-rock mining are applied in the Muckahi system as described in of the technical report, where applicable. The proposed application of a monorail system for underground transportation for mine development and production mining is unique to underground mining. There are existing underground mines that use a monorail system for transportation of materials and equipment, however not in the capacity of Muckahi which is described in detail in the technical report. The mine design, equipment performance and cost estimations involving Muckahi in the technical report are conceptual in nature, and do not demonstrate technical or economic viability.”

At the same time as updating the market on its plans to use conventional development and mining methods at Media Luna, Torex said its Board had approved a pushback of the El Limón open pit, which is anticipated to add around 150,000 oz of gold production and extend open-pit mining to mid-2024. This would align with first production from Media Luna in 2024.

Torex’s Stanford looks forward to big year with advancement of Muckahi Mining system

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It was a year of milestones for Torex Gold in 2019, with the Mexico-focused gold miner posting record operational and safety performance, alongside record EBITDA and free cash flow.

The company produced 454,800 oz of gold in 2019 and is guiding for 420,000-480,000 ounces in 2020.

From a technology perspective, the company also made significant progress on advancing its Muckahi Mining System, an alternative to established underground mining processes that, Torex says, can create a more continuous mining process able to accelerate return on investment.

The benefits of the technology include an up to 30% reduction in underground mining capital expenditure, an up to 80% reduction in time between investment and revenue, up to 30% reduction in mining operating expenses and an up to 95% reduction in underground greenhouse gas emissions, Torex says.

President & CEO, Fred Stanford, said: “On the Muckahi front, we successfully demonstrated the viability of the most innovative aspects of the mining system in 2019. We are now excavating our second 30° down ramp and are continuously improving the technique.”

The company is currently testing out the technology at the El Limón Deep zone (ELD) at its El Limón Guajes mining complex (ELG), in southwest Mexico.

Incorporating 30° ramps into mine designs will be a “game changer” for the industry, according to Stanford.

“Moving beyond tunneling to ore production, we demonstrated we could achieve ‘conveyable fragmentation’ when blasting a long hole open stope. The team then demonstrated they could completely ‘muck out’ the long hole open stope with a low cost electric slusher,” he said.

With the major innovations demonstrated as viable in 2019, 2020 will focus on optimising the processes tested in 2019, and initiating testing of the various conveyor applications in the Muckahi Mining System, Stanford said.

“A conveyor for the 30°-ramp has been designed, manufactured, and is currently in transit to the mine,” he said, adding that it will be installed in the ELD deposit in the June quarter.

“We all look forward to getting the conveyor installed and demonstrating the potential,” he said.

Torex makes Muckahi plans for newly declared gold reserve

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Torex Gold Resources has announced a maiden underground reserve for the El Limón Deep zone (ELD) at its El Limón Guajes mining complex (ELG), in southwest Mexico, and revealed plans to mine it with its newest innovation, the Muckahi system.

The probable mineral reserve at ELD contains 86,000 oz of gold in 487,000 t of material at an average grade of 5.5 g/t Au (cutoff grade of 3.7 g/t). This is a subset of an indicated mineral resource at ELD that contains 141,000 oz in 797,000 t at an average grade of 5.52 g/t Au (cutoff grade of 2.5 g/t).

The mineral resource at ELD is the downdip extension of mineralisation in the El Limón open pit, some 400 m north-northwest of the Sub-Sill deposit (already being mined) and is open in three directions.

Fred Stanford, President and CEO of Torex, said, while small in comparison to the open-pit mineral reserves, the ELD provides a “nice sweetener to the open-pit production”.

He added: “It is also indicative of the potential to add further underground mineral resources. With ELD open in three directions, the Sub-Sill underground deposit still open at depth, and the potential for down dip extensions of Guajes, we are upbeat about the potential to further expand underground reserves and resources through multiple sources.”

ELD will be accessed through the existing underground development and will use the existing site infrastructure, according to Torex. This infrastructure includes, but is not limited to, electrical facilities, maintenance facilities, main ventilation exhaust fans and the backfill plant. Depending on material availability and geotechnical requirements, all mining areas at the ELD will be backfilled with either cemented aggregate fill or uncemented rockfill.

While the mineral reserves for the ELD deposit have been estimated using conventional mining techniques and costs, the intention is to mine the deposit with the Muckahi mining system, Stanford said.

“If as expected, the costs associated with Muckahi mining are lower than conventional mining costs, we may be able to lower the cut-off grade and increase the size of the mineral reserve.”

Excavation of the 30° down ramp to access the lower parts of the ELD deposit is underway, with four rounds taken, according to Stanford. “In the upper portions of the deposit, the excavations are nearly completed for the initial long hole stopes that will be mined utilising the production aspects of the Muckahi system.”

Stanford also provided an update on the Muckahi system, which is currently undergoing trials at ELG. The first tunnelling blast of the field trials was taken on March 26 and the round was successfully drilled from the monorail mounted Muckahi jumbo drill. The second piece of equipment, the Muckahi service platform, was at the Mexican border as of April 3 and was expected to be in service this by the end of June.

The goal of the trial is to demonstrate Muckahi’s capabilities over the full development cycle for tunnelling, including on a minus 30° gradient, and to demonstrate the capability of the system to lower costs in long hole open stope mining.

Stanford said on June 20: “To date the Muckahi system has performed as expected, we are all eager to progress through the next stages of the testing program and, if proven, then move forward with the strategic options it has the potential to unlock.”

The Muckahi concept is an alternative to established underground mining processes that, Torex says, can create a more continuous mining process able to accelerate return on investment.

Learn more about the concept and technology by clicking here.