Cornish Metals Inc said it had made “very good progress” over the last eight months towards the start of tin production in 2026 at South Crofty mine in Cornwall.
DISCHARGE
The Canadian company has been working on the mine water treatment plant (WTP) along with continuing its drilling campaign.
The WTP is designed to treat 25,000m3 of mine water per day until the end of 2024 to dewater the mine.
Cornish Metals will discharge the treated mine water into the Red River via the Dolcoath deep adit.
“Since South Crofty closed in 1998, untreated mine water has directly entered the river, so dewatering the mine and treating the water will have a positive effect on the Red River water quality,” added the company.
PLANT COSTS
Cornish Metals completed the concrete foundation pad for the WTP in November 2022, and installed the first reaction tanks in December 2022.
The plant comprises nine installed reaction tanks for increasing and decreasing the pH to precipitate the various metals in solution, and six inclined plate settlers (lamella clarifiers) to remove the precipitated solids.
Four plate settlers are currently installed with completion of the remainder expected in early March 2023.
Installation is this week planned of the structural steel supports and walkways, surrounding and providing access to the WTP, with completion by the end of March.
Pipelines carrying water from the submersible pumps in New Cook’s Kitchen shaft to the WTP are substantially complete.
Mechanical, electrical and instrumentation equipment will begin installation in April and wet commissioning at the end of May, with completion due in June 2023.
“Construction costs for the mine water treatment plant remain in line with previous guidance of £6.5m to £7m,” said chief executive Richard Williams.
“The company remains on track to commission the mine water treatment plant in June this year, with the objective of commencing full scale dewatering operations in July.”
DRILL PROGRAMME
As part of the feasibility study, Cornish Metals chose five main lodes / mineralised areas within the mineral resource for metallurgical work, namely the North Pool zone, No. 4 lode, No. 8 lode, Roskear B/D lode and Dolcoath North lode.
The selected areas contain the majority of the mineralised material anticipated to be processed during the first six years of operation.
The company has two drill rigs currently operating in the North Pool zone from surface, and an underground drill rig targeting Dolcoath North from the Tuckingmill decline.
All mineralised sample material required from No. 4 lode, No. 8 lode, and Roskear B/D lode has been collected and initial metallurgical studies have started.
North Pool zone drilling and sampling is expected to complete by the end of March and all of the requisite metallurgical studies, except for Dolcoath North, are expected to complete by the end of 2023 for inclusion in the feasibility study.
“The metallurgical drill holes have encountered, highly encouraging tin mineralisation down dip of existing workings,” added Cornish Metals.
FUTURE WORK
Cornish Metals has employed a number of sub-contractors to advance the feasibility study.
Work includes designing the process plant and estimating capital and operating costs as well as numerical modelling and ground control studies for underground mining method and stope designs.
A study will also be conducted on the refurbishment, re-equipping and operation of New Cooks Kitchen shaft, which is the principal shaft for future operations.
A geotechnical site investigation for the process plant is already complete.
EXPLORATION
Following the recent discovery of the high-grade tin mineralisation in the Wide Formation at Carn Brea, the geology team plans follow-up drilling for better definition of the geometry.
The programme is expected to begin in June 2023, as soon as the metallurgical drill programme is completed.