Ironstone
The history of local ironstone mining and the development of the Tees Valley are intimately linked.
The history of Ironworking
The earliest smelting of ironstone in the area is traceable to c.400BC and the Iron Age. Later, in the 1200s, there is evidence of furnaces in Eskdale, at places such as Fryupdale and Egton. Heaps of furnace slag around Rievaulx Abbey marks the working of local ironstone by monks, a trade that continued until the mid-1600s. Evidence is then scant for around a century until we learn that nodules and boulders of ironstone were collected in summer from the scars by local coastal communities. The ironstone was loaded onto small boats grounded on the rocks nearby, before travelling to furnaces on Tyneside. Such seasonal work provided a welcome financial boost for villagers who usually relied upon fishing to survive. Ironstone collected at Robin Hood’s Bay fed the Whitehill Furnace, founded at Chester-Le-Street in 1745, for around fifty years, and the Tyne Iron Company obtained their stone from various scars between Saltburn and Scarborough until the mid-1800s.
Quarrying began in the late-1820s where the ironstone crops out on the foreshore at Kettleness, and later in Brackenberry Wyke east of Staithes. In 1835, a Mr. Wilson (partner in Losh, Wilson, & Bell – ironmasters on Tyneside) noticed ironstone in a cutting at Grosmont whist inspecting construction of the Whitby and Pickering Railway. Drift mines were soon operating with the stone going by rail to Whitby. Cleveland ore still travelled by sea to Wearside and Tyneside for processing, but all of this was soon to change.
When Bolckow and Vaughan sought a local source of iron for their furnaces in the new town of Middlesbrough, the Cleveland ironstone was the obvious choice. The opening of a drift mine at Skinningrove in 1848 spurred him on and, with the help of mining engineer John Marley, the quest moved North West to Eston. On 8th June 1850, the pair located a quarry from which road stone had been extracted for some years. On inspecting it, they found that the rock in question was the Main Seam of the Cleveland Ironstone Formation, which here lay some sixteen feet (4.8 metres) thick.
Bolckow and Vaughan’s success was soon being felt by other mining companies as the extent of the ironstone underlying Cleveland became clear.
Soon, shaft mines joined an expanding number of drift mines as the railway made its way into East Cleveland where the ore lies at depths up to 720 feet (220 metres). In 1881, Middlesbrough celebrated its jubilee and the miners in the Cleveland Hills responded with a total production of above six million tons – double the projected output – over a million tons from Eston alone.
The Iron Smelting Process
Ironstone arrived on Teesside by rail where it was initially placed in kilns, with coal or coke, to be strongly heated (calcined); this had the effect of driving off water and some of the unwanted sulphur resulting a concentration of the iron content from 33% in the raw stone, to 40%. Next, the ore was placed in a blast furnace and smelted, with the resulting iron being cast into ingots known as pigs. These would be later re-melted in a puddling furnace and the iron stirred to remove excess carbon making it malleable.
A major by-product of smelting was furnace slag, the disposal of which proved a costly affair for the ironmasters who were forced to rent land upon which to store it. The solution to this problem arose as the result of improvements along the banks of the Tees. Some slag, from the stockpiles along the River, was taken for reclamation schemes and the ironmasters would even pay four pence per ton for its removal. Slag was also cast into bricks in order to construct 22 miles of strong training walls to channel the River more efficiently. More recently, the North and South Gare breakwaters at Teesmouth are constructed upon foundations comprising millions of tons of furnace slag. Other by-products were utilised by the area’s growing chemical industry.
The discovery of a new method of the steel production (the Bessemer process) in the 1850s, which worked better using non-phosphoric ores unlike those available in Cleveland, could have been an early problem. John Vaughan, who engaged the help of two colleagues from Staffordshire to look at the problem, overcame it. They eventually contrived the successful Thomas-Gilchrist process, by which local stone could be processed into high-grade steel for world markets. This process is still used today in other parts of the world.
The industry’s decline was long and drawn out, commencing at the end of the nineteenth century, with the intervention of two World Wars which kept Cleveland stone flowing from the hills. After the second War, the tenacity and skill of Cleveland miners and ironworkers ensured that the industry might fade, but would never die in this proud region. Despite everything, mining of Cleveland Ironstone finally succumbed in 1964 with closure of the deepest, and last, of over eighty mines in the ore-field at North Skelton. Amongst the hills of Cleveland, which once resounded to the sound of steam-powered industry, stand the tumbled-down remains of these once great mines. Their ruins, today being gradually reclaimed by Nature, resound only to the gentle sounds of birdsong. However, their presence, in addition to the blast furnace at Redcar, works at Skinningrove, and the foundry at Guisborough all bear testament to the region’s rich industrial past.