Middleton Mine
This account of Middleton Mine was written in 1993.
Middleton Mine is located 4 miles south-west of the small town of Matlock. The mine works the Hopton-Wood Limestone which occurs underneath Middleton Moor. Middleton Moor is on the southern margin of an area of the Peak District known as the The White Peak, a block of carboniferous limestone stretching 50 kilometres north to south and 20 kilometres west to east.
Historical
It is difficult to pinpoint exactly when Hopton-wood limestone was first extracted on the site now occupied by Middleton Mine. Certainly by the 1900's there was a well established dimension stone operation at the site. It was a surface operation and was cut where the Hopton-wood outcrops on the eastern flank of Middleton Moor in the middle of the village of Middleton-by-Wirksworth.
Dimension stone operations continued until the 1950's when due to the rapid development of concrete technology the demand for natural stone products fell. Derbyshire Stone, the then operators and owners of the site, had pre-empted this fall in demand by developing a small processing plant to crush the limestone to supply the steel and sugar industry.
Towards the end of the decade the situation with the surface operations reached a point where it became increasingly uneconomic to keep stripping the overburden (which was increasing in depth as a quarry cut into the moor) to gain access to the high purity Hopton-wood beds. The Company was reluctant to lose the customer base it had built up with the processed products, so the decision to commence underground operations was taken.
The company at that time were operating a lead mine in Matlock and moved two of the personnel to Middleton. Work on a drift access was started on February the 4th 1959 and to date approximately 16 million tonnes of high grade limestone have been extracted for the underground workings.
At present Middleton Mine consists of 35 kilometres of workings covering an area of 1400 metres west to east and 800 m north to south. Middleton Mine is divided into five main production areas by normal faults.
In 1968 Derbyshire Stone was absorbed into the Tarmac Group who ultimately put the mine up for sale towards the end of 1990 along with two other units located in Derbyshire which formed it's Industrial Product Division The three Units were purchased by Croxton and Garry Limited who were owned equally by Pluess-Staufer and Blue Circle at the time of the purchase. Pluess-Staufer are now the sole owners of Omya Croxton and Garry.
Mining method
The current method of working is room and pillar, with rooms 13 m wide and pillars 17 m square. The extraction height is 8 m. This is an increase from the original pattern of 11 m wide roadways and 14 m square pillars.
The production cycle
The production cycle has five stages:
Scaling - when the loose rock is barred down from the face, roof and walls. This can either be done mechanically or by hand,
Drilling - the face is then drilled using a twin boom jumbo rig to a depth of 4.8 m. Sixty six holes are drilled per face in a wedge pattern.
Blasting - after drilling the face is charged using ammonium nitrate and fuel oil as the bulk explosive. Two or three headings a day are charged depending on production requirements and these are fired at the end of the working shift. Each blast produces approximately 950 tonnes and advances the face 4 to 4.5 m.
Loading - the blasted material is loaded by a Komatsu face shovel into 30 tonne dump trucks. These haul the blasted rock to an underground processing plant where the material is crushed and screened.
Crushing and Screening - the underground plant produced a feed for the Middleton Surface Plant, Hopton Plant and a Screened Aglime. The Surface Plant has tertiary crushing, screening and drying processes.
Manning
The distribution of the manpower is
Management 2
Underground 16
Surface Plant 7
Loading for sale 4
Maintenance 6
Apprentice 1
Clerical 3 [ inc 2 part time]
Cleaning Staff 1 [ part time]
Total 40
End use
Middleton Mine produces a range of products varying in size from 125 mm to 150 microns. These products are used to supply industries as diverse as glass making, sugar refining, mastic asphalt, vinyl floor coverings, bathroom ware, fertilisers and animal feed products
The largest single customer is the sister plant at Hopton where it is ground in various grades from 250 micron to 12 micron. The limestone is usually employed as a filler or extender in rubber, plastics, ceramics, adhesives and other industrial manufacturing process.
