Tag Archives: Media Luna

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

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.

First Muckahi mining system on site in Mexico, Torex Gold says

At the same time as reporting record gold production for 2018, Torex Gold has provided an update on its innovative in-development Muckahi underground mining system.

The company recovered from a blockade at its ELG mine, in Mexico, which affected operations earlier in the year, to produce 353,947 oz of gold in 2018, with 96,316 oz of that coming in the December quarter. Torex guided for production of 430,000 oz in 2019.

In tandem with these results, the company’s President and CEO, Fred Stanford, talked up the company’s Muckahi concept, an alternative to established underground mining processes that, Torex says, can create a more continuous mining process able to accelerate return on investment.

Stanford, who is credited as the originator of the technology, said in the company’s 2018 financial report: “If proven successful in 2019, the Muckahi technology will reduce the costs of future underground mining on the Morelos property (which includes the ELG and Media Luna assets) and will provide us with a competitive advantage when bidding on potential acquisitions and pursuing other options for commercial deployment.”

He said the testing programme for the Muckahi technology was expected to be completed in 2019, with the first of four Muckahi machines on site in Mexico. “We anticipate breaking rock with it in the next couple of months,” he said, adding that as the other machines arrive, the company would incorporate them into the test programme.

The planned use of the Muckahi system, which is also being developed with help from MEDATECH, in the most recent preliminary economic assessment for the Media Luna project saw the after-tax internal rate of return jump from 27% to 46%.

For 2019, Torex’s Muckahi plans include:
• Development on the level;
• Development on a 30° down-ramp;
• Long-hole open stope fragmentation to 95% passing 400 mm, and;
• Mucking a long hole open stope with a slusher.

Torex Gold’s Muckahi Mining System starting to take shape

Torex Gold has provided an update on its innovative underground Muckahi mining concept, saying the first piece of equipment is due to be shipped to its ELG operating mine in Mexico before the end of the year.

Significant testing of the system, which was factored into the recent preliminary economic assessment on the Media Luna project, was expected to be completed by the end of 2019, the company said.

The Muckahi Mining System is an alternative to established underground mining processes and requires the use of a one-boom jumbo, service platform, mucking machine and tramming conveyor to create a more continuous mining process that can accelerate return on investment, according to Torex. It also significantly reduces the ventilation needs in underground mines by using conveyors as the main transport solution, playing into the mine electrification theme that is gaining traction.

Use of the MMS in the most recent PEA for Media Luna saw the after-tax IRR jump from 27% to 46%.

The key expected benefits of using the MMS over conventional means are:

  • Continuous muck handling system and the elimination of re-handle and storage;
  • All-electric operation and significant reduction in ventilation requirements;
  • Ability to travel on ±30° (58%) slope and major reduction in both permanent and operating development;
  • Ability for bi-direction travel in 4m x 4m tunnel.

Muckahi Mining System set for underground testing in Q1: Torex Gold

The new underground mining concept put forward by Torex Gold’s President and CEO Fred Stanford is gaining some traction at the company’s early-stage Media Luna project in Mexico, with the new technology potentially able to cut upfront capital requirements, reduce operating costs and decrease the time to commercial production.

IM reported on the highlights of the latest preliminary economic assessment in an earlier story, which showed the after-tax IRR going from 27% to 46% using the Muckahi Mining System (MMS) concept. But, the filing of the latest technical report has brought out some more details.

The report states on MMS: “The system challenges the status quo in many ways with the goal of establishing more efficient and cost effective alternatives to established mining processes.”

The MMS requires the use of a one-boom jumbo, service platform, mucking machine and tramming conveyor to create a more continuous mining process that can accelerate return on investment. It also significantly reduces the ventilation needs in underground mines by using conveyors as the main transport solution, playing into the mine electrification theme that is gaining traction.

Stanford, who is credited as the originator of the technology, explains the design rationale in the report:
“The production system in a mine is effectively a serial set of processes, with the ultimate objective of delivering rock, at specification, to the processing facilities. Each process step will have a primary design objective of either transformation, transport, or storage. In some processes there will also be inadvertent, non-design, transformation. This inadvertent transformation is generally not a desired outcome (ore pass slough, oxidation, etc).

“It is quite common for the ‘rates’ or ‘availability’ of processes in a serial set of processes to be out of alignment/coordination with each other. When this is the case, the productive capability of the entire system is reduced.

“To increase the productive capability of the system, designers frequently insert storage processes between transformation and/or transport (T&T) processes. These storage processes serve to reduce the inter-dependence between T&T processes and thereby increase throughput. This can be an effective design feature to maximise output, but it is expensive.

“In an underground mine these storage facilities, whether they are for rock or supplies, must be excavated and equipped, which consumes capital. They frequently also require re-handling, which consumes operating dollars. A design objective for Muckahi was to eliminate the need for storage processes by finding ways to bring into alignment the rates and availability of the entire set of T&T processes.”

He continues: “If the quality (size) of the rock product from the primary blast is not adequate for downstream processes, then a secondary sizing process will need to be added to the ‘set of processes’. Having ore-passes in the mine design will also force a requirement for a secondary sizing process. This is due to the uncontrolled size of the wall rock that, over time, will slough into, and dilute, the ore product.

“Secondary sizing processes, particularly underground crushers, are expensive and time consuming to build and expensive to operate. A design objective for Muckahi is to eliminate large size secondary size reduction processes and just deal with minor oversize management with mobile rocker breakers or ‘chunk’ blasting.”

To materially reduce the capital, operating cost, and mine build schedule, the MMS design approach sought ways to reduce the number of process steps and make the remaining process steps more efficient.

This involved eliminating secondary sizing processes that required ‘constructed’ facilities such as a crusher station – thereby eradicating the need for ore passes – cutting out all storage facilities, and replacing the current logistics model of one-way traffic in large tunnels, with two-way traffic in tunnels half of the size.

Stanford said the MMS has been able to achieve all of these requirements on a conceptual level by using five solutions:

  • Blasting rock down to a smaller size – if the rock is to go directly onto a conveyor, then the product of the primary blast must be in the range of 95% passing -400 mm. Achieving this specification is not a challenge for ‘short hole’ primary blasts, such as used in development or cut and fill production mining methods. For ‘long hole’ production methods, it will require much tighter control of drilling procedures, explosives placement, and detonator timing;
  • Twin roof (back) mounted monorails in all tunnels – this technology from the European coal industry solves several of the design challenges. It provides a stable platform for ‘long and skinny’ loads, allows climbs up steep 30° ramps and two-way traffic (one rail for inbound traffic and the other for outbound). SMT Scharf Group and Becker Mining Systems are two companies currently supplying these systems to the mining industry;
  • A new transport concept named a ‘Tramming Conveyor’ (pictured) – this machine deals with the ‘first mile’ from the face/drawpoint, when straight lines for conventional conveyors are not an option. The conveyor is end loaded at the drawpoint until the belt is fully loaded. The belt then stops ‘turning’ and the whole unit drives away on the outbound rail to the discharge point. At the discharge point, the belts starts turning again and discharges its load (conveyor-to-conveyor transfer). The unit then switches to the inbound rail and returns to the drawpoint. While it was away from the drawpoint, other units have been loaded – hence, one of the benefits of two-way traffic;
  • Ramps at 30° instead of the conventional 7.5° – the rubber tyres on conventional equipment lose traction on gradients that are much steeper than 7.5°. The back-mounted monorails remove the need for rubber tyres, hence the ability to steepen the ramps to the 30° gradient that can be handled by the cog drive system;
  • Twin tunnels in waste – the tunnels in a Muckahi mine are half the volume of the tunnels required for a 50 t truck in a conventional mine. Half the volume means less rock to remove, less ground support, fewer holes to drill and load in the face, etc. This means they can be driven much more quickly. In a Muckahi mine, there are also no muck bays to be driven, which reduces metres by approximately 20%. The net effect is that excavation rates in a 4 m x 4 m tunnel should be two to three times faster than in conventional tunnel of 5.5 m x 5.5 m.

Torex said the concept is now shifting to the underground testing phase, with manufacturing of the first of the prototype machines underway in partnership with Medatech Engineering Services out of Canada. This could see the first trials underground at the company’s ELG mine in the March quarter.

In summary, the key expected benefits of Muckahi are:

  • Continuous muck handling system and the elimination of re-handle and storage;
  • All-electric operation and significant reduction in ventilation requirements;
  • Ability to travel on ±30° (58%) slope and major reduction in both permanent and operating development;
  • Ability for bi-direction travel in 4m x 4m tunnel.

Torex Gold’s Media Luna PEA to feature innovative Muckahi transport option

Torex Gold is weighing up the use of an innovative technology that could provide an efficient and cost effective means of moving people, mining devices, and ore out of steep underground mines.

The company, which is back in action at its ELG gold mine in Mexico after a long strike at the operation that started in 2017, said in its June quarter results that it had recently come to an agreement with its CEO, Fred Stanford, to acquire his interests in ‘Muckahi’.

Stanford conceptualised and patented the Muckahi process and has been working with Canada-based engineering firm MEDATECH to develop his methods and come up with the necessary equipment to make his process work.

Muckahi makes use of overhead rails as an efficient and cost effective means of moving people, mining devices and ore out of steep underground mines. The modififed machinery also allows for increased production rates and less handling, moving the process towards continous production, according to MEDATECH.

The mining system is currently in the evaluation stage, but is being considered for use at Torex’s Media Luna gold project in Mexico. There is a revised preliminary economic assessment on Media Luna due soon that is expected to feature the use of this technology.

The 2015 PEA on Media Luna envisioned an underground operation with expected average annual production of 313,000 oz of gold-equivalent at an average all-in sustaining cost of $636/oz.

The recovery of the Media Luna resource was planned to be through underground mining methods at 7,000 t/d with the mineralised material transported via a hybrid underground/aerial/underground rope conveyor to the ELG processing plant. The conveyor belt would be 6.7 km in length with a 360 m vertical drop over its length.

Torex said it was planning to run a technical session for investors and analysts on the Muckahi process next month.