Wheal Jane Mine, in common with other mines in the area, produced tin and copper, plus a range of other minerals arsenic, sulphur, tungsten, zinc, silver, iron and ochre. Drainage of the Wheal Jane area has always been a problem.
West Wheal Jane produced 410 tons of black tin, 50 tons of
copper ore 26 tons of 74% lead ore, 158 oz of silver, 390 tons of zinc ore,
27,170 tons of pyrite, 382 tons of arsenic and 207 tons of iron ore from gossans
during the period of
Wheal Jane produced 3,832 tons of black tin, 740 tons of 4% copper ore, 302 tons of 64% lead ore, 2,921 oz of silver, 586 tons of zinc ore, 33,340 tons of pyrite, 86 tons of arsenopyrite, 243 tons of arsenic, 100 tons of ochre and 3,666 tons of iron ore from gossan during the period of 1847-95.
Wheal Jane is sited in an area with previous working which may date back to 1740.
1861-East Wheal Jane formed from five smaller mines.
1884-Mining in the Wheal Jane area ceased: the mines were to antiquated and too poor to survive.
1906-Wheal Jane and its adjoining mines were re-opened and operated as Falmouth Consolidated Mines. They tried to reduce costs by using electricity for pumping. However costs were still to high and the mine closed in about 1915.
In the Mid. 1960's Consolidated Gold Fields investigated the economics of re-opening Wheal Jane. They believed that up to date metallurgical methods for handling low grade tin concentrates and modern mining techniques could make the mine pay.
1969- Consolidated Gold Fields re-opened the property, at an estimated capital cost of £6 million.
They needed to sink a new shaft (No. 2) to 366 metres; deepen and widen the existing Clemows shaft to 234 metres with the subsequent construction of an underground crusher station; and install full surface support services.
A new type of concentrator was designed incorporating froth flotation for the recovery of tin. The concentrator could mill 600 tonnes a day. High grade and low grade tin concentrates were sent to Capper Pass Smelters in East Yorkshire, and copper/zinc concentrates to Sweden via Truro Harbour.
Underground, horizontal tunnels were developed from the shaft every 30 metres vertically in depth. Ore was extracted from 10 metres wide panels by drilling, blasting, and loading into trains for transportation to the shaft system and crusher.
But by 1970's Consolidated Gold Fields concluded that the mine was uneconomical. The government paid to keep the pumps going to prevent flooding and the mine was then taken taken over by Rio Tinto Zinc (RTZ)
Initial production supplied 10% of the UK's tin consumption. The work force reached 440, and 98 houses had to be built in Truro to accommodate the extra workers. The mine produced tin, copper and silver. Annual production of tin peaked in 1973 at 1600 tonnes, declining to 951 tonnes in 1977 before closure in 1978 due to the increase in pumping costs when the adjoining Mount Wellington mine was closed.
RTZ used Thyssens to redevelop the mine and William Press the mill. But RTZ could not make it pay, and sold out to a management consortium.
Production restarted in 1980 reaching 1499 tonnes of tin in 1981 and 1863 tonnes in 1984.
1991-The Mine was again found to be unprofitable, and the pumps were switched off in January 1992
When the pumps stopped, the ground water level rose,and built up a pressure
that it burst the drainage system. Millions of litres of toxic metal-rich water
were released into the Carnon River and contaminated the whole river system
down to the estuary in Falmouth Bay.
In 1994, the Wheal Jane Pilot Passive Treatment Plant was installed, which used only organic methods such as lime stone solutions, reed beds and rock filters to reduce toxic elements in the mine water. The water now released into the Carnon is probably cleaner than at any time since mining began. The long-term effects are nevertheless noticeable because waterbirds still continue to die from lead and zinc poisoning.
J.A. Buckley, K.T. Riekstins, P.R. Deakin (Illustrator)
Carnon Valley Mines