Hemerdon Tungsten Mine

 

Hemerdon Ball is a granite outcrop about about 3km outside the Dartmoor National Park. The tungsten deposit was initially discovered in 1867 but further exploration in 1916 revealed a wide-spread, low grade wolframite deposit. It can only be worked economically by large-scale open-cast working which leaves a huge amount of spoil. Tungsten is a high value metal essential for many modern technologies. Anxiety about world supplies during the World Wars stimulated development between 1917 to 1920 and 1934 to 1944. After the war tungsten prices fell and the mine was abandoned but most of the buildings erected during the Second World War are still standing. {jcomments off}

Core Samples at Hemerdon

AMAX, an American mining company, took over the lease for the mine in 1977 and exploratory work took place into the early 1980s to establish the extent and richness of the ore body. This involved over 25km of drilled cores, an edit for bulk samples and trial processing to establish recovery rates. Amazingly, most of the cores are still stored in a large shed on site. The conclusion was that the Hemerdon site has one of the largest tungsten deposits in the world, outside China. In 1981 AMAX submitted a planning application to mine tungsten and tin. This was refused at a public enquiry in 1984, but a revised application was granted in 1986 by Devon County Council, subject to stringent conditions governing the development and operation of the mine. Until recently the world price of tungsten has not justified development but AMAX did enough work on site to keep the permission alive, and it remains valid until 2021.

 

With the growth of its economy, China needed all of its supply of tungsten. This caused the world market price to rise significantly. So in December 2007, Wolf Minerals (UK) Limited announced that it had secured a 40 year lease on the site from the Hemerdon Mineral Trust and that it was planning to implement the existing AMAX permission. Wolf raised funds to update the AMAX feasibility study and carried out more core drilling and further dressing and metallurgical work. It concluded recently that the deposit is more extensive and with modem techniques the ore more recoverable. It is therefore, potentially more profitable than the earlier studies indicated.

 

The world financial crisis caused a slow-down in 2008-9 but now there seems to be a renewed interest in reopening the mine. A public meeting was held in Sparkwell in November 2009 where a member of Devon County Council, which is the Mineral Planning Authority for the area, outlined the background and explained the proposals. A representative from the Environment Agency was there and detailed the very stringent conditions under which work could be carried out. Wolf Minerals, the developer, was also present to answer questions. In addition other public meeting have taken place. Stephen Reed, archaeologist with the Devon County Council's Historic Environment Service, attended one of them. He is responsible for agreeing with Wolf what archaeological work must be carried.

 

The proposed development is huge. The planning permission allows for an opencast pit that could eventually be about 850m long, 540m wide and 200m deep. The planned processing plant will be able to process three million tonnes of rock per year over an operating period of about 13 years, producing an estimated 3500 tons of tungsten and 600 tons of tin per year. The tungsten and tin ores are separated magnetically in the final processing. The new plant will be situated near Drakeland Comer. The spoil heap could eventually cover a large part of Crownhill Down (an area rich with prehistoric, medieval and tin working archaeology) from Hooksbury Wood in the west almost up to the top of the Down.

 

The permission requires, at Wolf’s expense, the prior construction of a new stretch of road towards Plympton. Incidentally this would also benefit secondary aggregate lorries coming down from the clay works at Lee Moor at no cost to them. The permission requires the developer to provide a bond for restoration at any stage within the development and to purchase any properties affected. It allows the Lee Mill road across the Down to be diverted to the west if necessary in order to accommodate the maximum spoil heap. Several rights of way across the Down would disappear.

 

Wolf has employed a number of UK consultants to cover the technical and environmental aspects of the feasibility study in detail. An ecological survey has been completed and the archaeological assessment of standing buildings and fieldwork remains is underway. Discussions are in progress between Wolf and Devon County Council to bring some of the conditions of the 1986 permission up to date, to agree a revised restoration plan and an improved framework for the archaeological investigations. Wolf hope that these changes can be settled, the feasibility study completed and further capital raised this year so that the new road can be built in 2011, enabling development to begin in 2012 and production following on quickly after that..

 

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