August Cornish Mining Sundowner: alumni surprises and news of South Crofty progress

Despite the Cornish mizzle, there was an excellent turnout at last night's Cornish Mining Sundowner, at Falmouth's Chain Locker,  with welcome appearances of several Camborne School of Mines mineral processing alumni.

With CSM mineral processing alumni Nick Wilshaw (1980), Phil Moore (1982),
Pete Flitcroft (1984), Jim Turner (1984) and Dave Wardle (1984)

It was good to see Mike Hallewell back at the sundowner, having missed the last few due to pressure of work. He is a busy metallurgical consultant, involved with Eloro Resources in Bolivia and, closer to home, the revival of South Crofty tin mine. He told me that progress is being made with the new mill flowsheet at South Crofty based on practical experience operating the historical circuits before the mine closed in 1998 and incorporating modern technologies that have evolved in the interim period.

With Mike Hallewell

The original flowsheet used dense medium separation (DMS) as a preconcentration method; the proposed flowsheet will likely use a combination of DMS and XRT ore sorting. After coarse grinding via a rod mill, spiral concentration (previously used at South Crofty Mill) will be used to remove coarse liberated cassiterite prior to ball milling, with Mozley Multi-Gravity Separation (C902 MGS) units replacing shaking tables in the finer size fractions, as the capacity and efficiency of shaking tables decreases with decreasing particle size. The original fine tin flotation circuits were technically challenging and sensitive to pulp temperature and water chemistry so a study is currently underway to look at a simpler and lower cost gravity roughing stage using Falcon Continuous Concentrators, followed by C902 MGS cleaning. 

Mike was the longest serving Mill Superintendent at Wheal Jane (1991-1998) where he oversaw the metallurgical developments in 1993 which brought the tin recoveries to record highs that were the envy of the world. He is very proud and delighted to be back as part of the Cornish Metals team, which continues to progress work plans and accomplish key milestones, particularly the completion of the Preliminary Economic Assessment of the South Crofty tin project that confirms the Project’s potential to be a low-cost and long-life tin mining operation. Mine dewatering is still proceeding, with treated water being discharged to the Red River exceeding the standards permitted by the Environment Agency. The priority and focus is on advancing South Crofty towards commencement of production in 2027.

It was a great Sundowner last night, and the next one, at the Chain Locker, will be on Thursday September 19th.