West Mine was excavated during the period 1857-1878 and is the biggest mine at Alderley Edge. In 1858 an ancient gallery was discovered which suggests earlier mining had taken place using the fire-setting method [2]. However, the possible early mining was small scale and the mine as we know it is due to the activities of the Alderley Edge Mining Company. The miners were working two sandstone impregnated orebodies trending NW-SE [2]. One orebody yielded copper and cobalt in the form of malachite, azurite and asbolite while the other contained lead in the form of cerussite. Silver was also extracted from the ore in small quantities.
During the period 1857-1860 the ore was extracted by the opencast mining method which created a large quarry on the gentle southern slope of the Edge. There were three mineralised beds of sandstone (referred to as the N° 1 - 3 Beds or Top, Middle and Bottom Beds) which were separated by layers of barren rock [2]. The ore minerals were distributed in large, irregular patches but were concentrated above clay beds and adjacent to certain faults [2]. Although all three beds were mined, the N° 1 or Bottom Bed was most productive and gunpowder was used to blast the ore before miners broke it up into manageable pieces [2]. A treatment works was built nearby to process the copper and lead ore.
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Figure 1: The huge entrance stope in West Mine (image courtesy of the DCC) |
By 1860 the opencast mining operation was producing 1,000 tons of copper ore a month and several exploration levels were driven into the walls of the quarry [2]. One of the tunnels driven into the NW wall of the quarry encountered a rich ore-shoot, and the extraction of both mineralised and barren rock began [2]. A huge cavern (known as a stope) which is cathedral like in proportions was created as a result of this method of mining (fig. 1).
By 1861 the distance to the treatment works was considerable which created logistical problems. The decision was made to mine only the three layers of mineralised rock and the mine took the form of three levels as a result. Shafts were dug to connect these levels and pillars of mineralised rock were left as supports [2]. The miners worked by candlelight, drilling 'shot holes' into the rock which they filled with gunpowder before adding a fuse and sealing it with clay [2]. Mining in this way had its dangers and accidents were not uncommon. It was common practise to backfill the tunnels with waste rock rather than transporting it outside [2].
The ore was transported through the mine using wheelbarrows and wooden trucks running on a system of wooden and iron rails. The mined rock was also tipped down 'box-holes' where it accumulated at the haulage levels [2]. As the mine expanded westwards the ore had to be brought 'uphill' to the exit of the mine and an inclined level was constructed to solve the problem (fig. 2). Wooden trucks were pulled up a railway by ropes attached to a steam engine at the surface [2].
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Figure 2: The haulage level in West Mine used to bring ore out of the mine (image courtesy of the DCC) |
Mining continued throughout the 1860s with the copper ore grade averaging 2.5 %, a value which was considered highly satisfactory by the Alderley Edge Mining Company [2]. In 1864 a fault was encountered which had displaced the mineralised layers and thus caused some problems. Several exploration levels were dug under the direction of the mine manager and the ore was relocated [2].
By the late 1860s the mine was becoming depleted and output fell considerably. The operation was struggling to extract 8,000 tons of copper ore per annum during the following years, less than half of that extracted during the 1860s. Mining continued throughout the 1870s although the price of copper was falling as a consequence of overseas competition [2]. The Alderley Edge Mining Company went into voluntary liquidation in 1878 when negotiations to renew the lease failed [2]. West Mine was abandoned and the haulage level fell into disrepair over the coming years [2].
In 1909 there were rumours that the mine was to be reopened and in 1911 workmen began clearing the entrance [2]. The new enterprise struggled and lasted two years before the ownership was transferred to a Mr Gibb in 1914 [2]. Once again there was very little ore extracted and mining ceased in 1916 [2]. Alderley Copper Ltd was the last company to work the mine when mining began in 1918 but this was also a small venture [2]. In 1919 the mine was abandoned for the final time and remained disused until 1961 when it was sealed. During this period the mine was the scene of several accidents and fatalities, earning West Mine a reputation which is still well known today.
A gaping entrance in the northwest wall of the West Mine Quarry (now infilled) led to the huge underground entrance stope. A level excavated into the southern wall of the entrance stope (known as The Canyon) leads to Twisted Pillar Cavern and Sphinx Chamber [13]. A steep incline leads from the Sphinx Chamber to the Plank Shaft which was the scene of a fatal accident. A series of tunnels on the other side of Plank Shaft brings you to another large stope known as the Great Arroyo [13]. The mine then turns towards the northwest and the Chain Shaft is encountered, which connects all three levels [13]. All three levels can be followed to the end of the mine and various stopes such as the Springboard caverns are encountered [13]. There are also other tunnels of various sizes found in the mine. Figure 3 is a simplified plan of West Mine.
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| Figure 3: A plan of West Mine displaying the main features (adapted from [2]) |
Copper
Advances in technology meant that the ore from Alderley Edge could be mined for profit during the second half of the 19th century. The ore was crushed into 1 cm pieces and placed in containers with perforated bottoms covered by straw [2]. Hydrochloric acid was then added to the containers in both fresh and recycled forms until all of the copper had dissolved [2]. The solution produced passed through the bottom of the containers and was pumped into precipitation tanks (the purpose of the straw was to separate the waste sand which was subsequently washed to remove excess acid and dumped on the sand hills) [13]. Scrap iron was added to the precipitation tanks which triggered a chemical reaction whereby the iron was dissolved at the expense of copper [2]. The accumulated copper particles were removed and washed with water before being dried and taken away for smelting [13].
Lead
The lead ore was ground between burr-stones and washed which separated the heavy lead (in the form of cerusite) from the lighter sand grains [2]. In 1863 the treatment of the lead ore was improved but shortly afterwards the Alderley Edge Mining Company encountered problems [2]. In an attempt to extract more lead the treatment works were having difficulty in separating it from the waste sand. These problems went unsolved and resulted in the closure of the lead treatment works in the early 1860s.