Tag Archives: Richard Williams

South Crofty pre-con, ore sorting test work implies improved project economics, Cornish Metals says

Base metals, Comminution of minerals, Energy minerals, Environmental, Mineral processing, Mineral project development, Mining equipment, Mining services, Precious metals, Sustainable mining, , , , , , , , , , ,

Cornish Metals Inc has received results back from TOMRA Sorting GmbH that indicate X-ray Transmission (XRT) sensor-based sorting could be a viable option for its South Crofty tin project in the UK.

The feasibility study on South Crofty, a iconic former producing copper and tin mine with first documented production history dating back to 1592, is advancing on schedule with a substantial amount of the study completed, Cornish Metals said. The mine was the last tin operation in Cornwall to close in 1998.

Metallurgical test work and heavy liquid separation (HLS) pre-concentration test work provided “excellent results”, the company said.

Conducted on samples from the 2023 metallurgical drill program across five mineralised zones (No. 4 Lode, No. 8 Lode, Roskear B/D Lodes, North Pool Zone and Dolcoath South), it represented the majority of the potential production areas in the first six years of the proposed mine life, according to Cornish Metals.

The XRT work came back with a 55% mass rejection and less than 3% metal loss (-50 mm – +15 mm size fraction), while the HLS testing saw a 50% mass rejection and lesss than 5% metal loss (-15 mm – +0.85 mm size fraction).

The XRT ore sorter test work of bulk composite samples was completed by TOMRA Sorting GmbH, with the HLS test work of bulk composite samples completed by Wardell Armstrong International.

Cornish Metals said: “The test work results confirm the upgrading potential of South Crofty mineralisation and enables continuation of the process design optimisation work to reduce the size of the mineral processing plant and materially lower capital costs, operating costs and environmental footprint.”

Richard Williams, CEO and Director of Cornish Metals, said the company expected the mineralisation at South Crofty to respond well to XRT ore sorting, but these results exceeded “our most optimistic expectations”.

He added: “We expect this result will have a positive effect on the project economics, allowing for lower power consumption and a smaller process plant and therefore lower capital and operating costs.”

In addition to ore sorting test work, the following feasibility study components have also been completed:

  • Headframe structural modelling and refurbishment;
  • Schedule and costing for the refurbishment and recommissioning of New Cooks Kitchen and New Roskear shafts;
  • Televiewer investigations and geotechnical rock testing to confirm known historical structural and rock mass property data;
  • Conceptual numerical modelling of the proposed underground mining methods and stope designs. Back analysis supports historical operating data. Ground conditions and excavation stability are expected to be very good;
  • Phase 1 of the metallurgical testwork program (mineralogy, physical competency, characterisation and gravity response test work). The gravity response results are very good and confirm previous operational results;
  • Concept engineering on paste backfill options and sighter test work; and
  • Ground investigations for the new mineral processing plant.

The following dtudy components are currently underway:

  • Mineral processing plant design, layout and capital cost study, incorporating the results of the metallurgical test work program reported today and potential future throughput expansions;
  • Underground mine design and optimisation using the latest South Crofty resource estimate published in September 2023;
  • A mine ventilation study, underground infrastructure design and hoisting analysis;
  • A feasibility study-level engineering design for the paste backfill plant;
  • Hydrogeology, environmental, social, marketing and closure studies; and
  • AMC Mining Consultants has been appointed to independently review and compile the feasibility study with initial gap analysis and site visits completed.

McLanahan and Mincore collaborate on gold processing plant upgrade

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McLanahan recently helped process consultancy firm, Mincore, come up with a solution for managing the gold leach tailings at one of Australia’s oldest gold operations near Bendigo, Victoria.

With the gold processing plant recently undergoing a series of process upgrades, several technology partners were engaged by Mincore. McLanahan was one, with its 10M Elevated Thickener coming into play.

Richard Williams, McLanahan Global Product Manager, said: “Mincore and McLanahan have worked on a number of project studies previously. Having local engineering capability and support on both sides made the engagement much more efficient in being able to review process data and confirm the specific thickener operation and construction requirements.”

Williams said a local manufacture and relatively low overall delivered cost solution would be the best fit for the client. “Modular design provides the flexibility to manufacture in more locations and provides more certainty around time-sensitive projects,” he explained.

Due to the nature of the processing plant, Mincore specified material and design aspects to account for the highly acidic and corrosive process streams, according to McLanahan. A specific sealant was procured for the thickener flanges to perform at the correct duty, as well as stringent paint quality assurance including DFT, WFT, pinhole and holiday testing specified by Mincore to confirm coating integrity.

The thickener was designed in-house at McLanahan’s New South Wales location and included several process instruments, including bed pressure, bed level, rake torque and overflow clarity. The tank, support structures and bridge were all manufactured locally for a faster delivery time, taking only 14 weeks for final delivery to the customer’s site, according to the company.

Mincore’s site team was able to support installation by using four experienced technicians and one small mobile crane to place the thickener onto a prepared concrete-bunded hardstand. The modular nature of the tank and bridge allowed for safe, fast and efficient site installation, McLanahan remarked.

Dry commissioning includes checking for correct tank assembly, along with the installation and application of protective treatments, the company said. “During this time, the drive and instrumentation are wired, and the mechanism is checked for correct alignment.”

Once successfully completed, a wet commissioning will be conducted, where the feed to the thickener is introduced and the process outcomes are evaluated for consistency. The process will ensure the instrumentation is operating correctly, and that the data received, and process outcomes, meet the design requirements and overall client specifications.

For this thickener, McLanahan’s customised approach included minimising the number of different fastener sizes and increasing assembly speed by minimising tooling and guesswork on site.
Additionally, McLanahan designed in the following aspects:

  • Integrated lifting attachment points preventing damage to paint and eliminating the need for the customer to source specialised lifting equipment;
  • A completely match-marked assembly system using large weld metal as marking to increase assembly speed;
  • Integrated electrical cable trays and conduits that reduce site work and damage to paint coating;
  • Local marshalling panel readout of all instruments complete with trending and status providing operator feedback in real time without needing to return to the control room;
  • Maximised space and clearance under the tank, facilitating pump and instrument access and maintenance; and
  • Integrated product sampling points at multiple locations around the tank to confirm process outcomes.

Strongbow gains local council backing for South Crofty mine re-start plan

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Cornwall Council has voted overwhelmingly in support of a £1 million ($1.3 million) investment into Strongbow Exploration, according to the tin-focused company.

The news follows a press release late last year that stated the council had voted unanimously in favour of the proposed investment, subject to Strongbow adding a dual listing on the London’s AIM exchange to its existing Toronto listing.

Richard Williams, Strongbow CEO, said: “We welcome this very positive decision for the project, which reflects the high level of cooperation between the local community, Cornwall Council and Strongbow, where all parties share the common goal of responsible mine development in an urban environment and high quality job creation.

“We look forward to advancing the project to a production decision.”

Cornwall Council Cabinet Portfolio Holder for Planning and Economy, Bob Egerton, said: “Cornwall has a global reputation for exporting expertise and knowledge in mining and the council is clear in its desire to support this sector to re-start production in Cornwall and bring with it much needed high-value jobs. If successful, restarting mining at South Crofty could create over 300 jobs and make a real difference to an area with high levels of deprivation.”

South Crofty is an iconic former producing copper and tin mine located in the towns of Camborne and Pool, Cornwall, England. The first documented production history from South Crofty dates back to 1592, and it was the last tin mine to close in Cornwall in 1998.

The project received an underground permission (mining licence) in 2013, which is valid until 2071, and planning permission to construct a new process plant in 2011. In October 2017, Strongbow was successful in securing a water discharge permit allowing for the dewatering of the now flooded mine workings.

Strongbow is now focused on completing the listing on AIM and completion of the water treatment plant so the mine can be dewatered. Strongbow plans to bring the project to a production decision and complete a feasibility study in parallel with the mine dewatering process.

A 2017 preliminary economic assessment on South Crofty outlined an eight-year project that mined 2.575 Mt of mineralised material with an average grade of 1.55% Sn-equivalent. Strongbow estimated it would require $118.7 million in pre-production capital expenditure to get the mine re-started.