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.