TRANSACTIONS OF SECTION B. 443 
further expenditure of fuel, and for this purpose raw coal was gasified in 
producers at the steelworks, and a further quantity sometimes burned under 
boilers to provide steam power for the rolling mills. Now, for every ton of 
pig iron produced at the blast furnace, about 1:35 tons of coal had to be coked 
at. the colliery, and a further 0'4 ton of coal had to be gasified in producers 
during the conversion of the iron into steel in open-hearth furnaces; thus, 
approximately, 1°75 tons of coal were used per ton of steel ingots produced, not 
te speak of any further fuel required to drive the rolling mills. 
Nowadays, with the concentration of by-product coke-ovens, blast-furnaces, 
steel furnaces, and rolling mills in one plant, it has become possible to carry 
through the whole process for the smelting of the iron ore to the finished girder, 
rail, or plate with the expenditure of no more coal than must be coked for the 
blast-furnace. And the credit of having achieved this revolution—an industrial 
romance if ever there was one—must be ascribed to British and Continental 
metallurgists in equal shares. The following figures will explain how this has 
come about. 
The blast-furnace produces not only iron but, as a valuable by-product, com- 
bustible gas, some 168,000 cubic feet (at 15° C. and 760 mm. pressure) per ton of 
iron. A furnace making 1,000 tons of iron per week (quite a moderate output) 
will produce every hour approximately a million cubic feet of gas, containing 
nearly 30 per cent. of carbon monoxide, its chief combustible constituent. Its 
net calorific value is nearly 100 B.Th.U-s per cubic foot. Some 60 per cent. of the 
gas is absorbed in generating and heating the blast for the furnace and in 
leakages, leaving a surplus of 40 per cent. available for purposes outside the 
blast-furnace plant. In times past, and even to-day in cases where the blast- 
furnace plant is isolated from the steelworks, this surplus was largely wasted. 
But where steelworks are adjacent to the smelting plant, as in all the newest 
installations, this surplus gas, which leaves the furnace at a temperature of 
about 300° C. and heavily charged with dust, is cooled and cleaned for gas-engine 
purposes. The power which could thus be generated is more than sufficient to 
provide for all the mechanical work required both on the steel plant and for the 
electrically driven rolling mills; the surplus gas not so required may (admixed 
with coke-oven gas) be used instead of producer-gas for firing the steel furnaces, 
svaking pits, &c. And even after all these requirements have been fulfilled 
there may remain a final surplus, convertible into electrical energy for outside 
uses, 
At the Seraing Works of the ‘Cockerill Company, who were the first to build 
large gas-engines for blast-furnace gas, there are to-day seven blast-furnaces 
producing some 7,000 tons of pig iron per week; if the whole of the surplus gas 
were utilised in gas-engines driving electric generators, no less than 28,500 
E.H.P. could be generated continuously day and night. This is probably more 
power than would be required for the steelworks and rolling mills. Accordingly, 
only 18,500 E.H.P. are being generated, with a thermodynamical efficiency of 
23 per cent., the surplus gas being used for heating purposes. So much, then, 
for the potentialities of blast-furnace gas. 
But to provide the coke required at the blast-furnace per ton of pig iron 
produced, about 1°35 tons of coal must be carbonised in the coke-ovens, and 
with the most modern by-product ovens of the ‘ regenerative’ type this means 
a possible recovery of about 30 lb. of ammonium sulphate, benzol, tar, together 
with an available surplus of 6,000 cubic feet of gas of an average net calorific 
value of 500 B.Th.U.s per cubic foot. Such a gas is admirably adapted for the 
enrichment of blast-furnace gas, for the firing of soaking pits, open-hearth fur- 
naces, and the like, thereby displacing altogether the specially generated ‘ pro- 
ducer-gas’ now almost universally employed. 
The total thermal value of the combined surpluses of blast-furnace and 
coke-oven gases per ton of pig iron produced, which may be nowadays 
considered as available for the steelworks and rolling mills, is somewhat as 
follows :— 
B.Th.U.s 
6,000 cubic feet of coke-oven gas = 6,000 500=3 millions 
65,000 5 blast-furnace gas =65,000 x 100=63 ___,, 
Total = 9-5 millions 
