Volume Twelve - Pre-Victorian to the Present Day - further aspects - The River Ely Iron Ore Wharf . . .

Soft Bessemer steel, made at Dowlais, by blowing the metal until it contained about 0·10 per cent. of carbon, and then adding 3·1 per cent. of spiegeleisen, previously broken so as to pass through a ¾-inch screen, and heated to redness, but not melted. 251 lbs. of spiegeleisen used to 72 cwt. of pig. The steel, though extremely mild, is reported to have rolled well. Authority: G. J. Snelus, "Journal Iron and Steel Inst.," 1874, p.79.

Sidney Gilchrist Thomas (1850-1885) of London and his cousin Percy Carlyle Gilchrist (1851-1935), a chemist at Blaenavon Ironworks, carried out secret experiments using a Bessemer converter at Blaenavon. During 1878 they had found a solution to the removal of phosphorus from iron ore by lining the converter with limestone bricks which resulted in the phosphorus reacting with calcium and its absorption into the residual slag. Subsequently, Thomas announced at a meeting of the Iron and Steel Institute of Great Britain 'that he had successfully de-phosphorised iron in the Bessemer converter.'

The use of the Gilchrist-Thomas innovation was, however, short-lived due to the steel producers in the northern outcrop area of South Wales investing in alternative sources of ore, plus, the additional expense of furnace linings which required regular replacement, plus, royalties payable, all of which combined to make their innovation uncompetitive.

The alternative process for the conversion of pig-iron to steel available from the mid-1860's was the Siemens-Martin process. It basically consisted of two open-hearth, brick-lined, chambers containing molten ore. Coal gas was injected into the first chamber which was ignited on contact with the molten iron and then the resultant gases were drawn down through the second chamber. The process was periodically reversed and heat from the intermediate brick wall between the chambers heated the incoming gases. The process was slower and much more energy hungry than the Bessemer process but its advantage was improved control of the quality of the end product and higher grades of steel were possible.

Up to 1840 local ironstone was almost exclusively used in the manufacture of iron but the availability of iron ore shipped from Cumbria from the 1850's at a reasonable price (Cumbria boasted that it had the largest and highest-grade red-hematite ore deposits in the land!) made it uneconomical for these northern outcrop ironworks to compete in the most commonly specified grades of iron. By 1856, about 325,000 tons of ore per annum was being shipped from the docks at Barrow and Whitehaven to South Wales. Those ironworks who failed to turn over their works to steel-making by the 1880's were no longer viable concerns and died.