COMPARATIVE ECONOMY OF THE BESSEMER OR PNEUMATIC PROCESS.
By this method of making steel, a great saving of fuel is secured. The product is in a cast condition ; and hence, in comparing it with the cementing process, we will consider the expenditure in producing ingots by each plan.
It requires for 1 unit of steel 2i units of coal to produce from the pig the cemented or blister steel; and for 1 unit of steel 2 units of coke to fuse this cement steel, and from therefrom ingot cast steel. Supposing the coke to represent 60 per cent. of the original coal, we have, upon addition, 7 units of coal necessary to produce 1 unit of common cast steel.
In the pneumatic process, using iron directly from the blast-furnace, no fuel is abso lutely required, except what may be necessary to heat the interior of the converter: the power to drive the blowing-machine may be water. To heat the converter requires of a unit of fuel to a unit of steel.
If, however, we suppose it necessary to remelt the cast iron in a reverberatory fur nace, it requires 60 per cent, of the weight of iron in coal to perform this office.* Hence we may conclude that 1 part of fuel in the Bessemer process will produce as much steel as 6 or 7 parts in the old method by cementation, and that hence there is a saving of to .1 in the amount of fuel necessary.
The labor, the keeping up of the machinery, the consumption of fire-clay, are items small in amount when summed up and compared with the same in other processes. At Woolwich, Bessemer estimated that steel could be sold at $34 per ton when pig iron was costing $18 per ton. Of course, this proportion will vary with different coun tries. The chief economy is in the fuel, which is an important fact to be considered
by the inhabitants of those regions where fuel is dear or of inferior quality; and the process may lead to some most important revolutions in the iron-industry of the world, by transferring the business to regions hitherto unfrequented by iron-manufacturers.
The discovery of this method of making steel was peculiarly opportune. No process ever was invented at a moment more favorable for its development. The metallurgic era in which we live demands vast quantities of steel in large masses. We have left behind us the day when quality alone was considered: quantity is now our uppermost idea. We are clamorous for processes to economize time. This furnishes the most sanguine with all he can desire. In less than an hour the liquid cast iron can be con verted and drawn into merchantable steel; the process of cementation requires, to pro duce the same results, the tedious lapse of several weeks.
The usual method supplies ingots of from 40 to 80 pounds weight, which only by great efforts may be increased to several thousand pounds. With this plan we may cast with ease an ingot of 10,000 pounds; and by using several converters at the same time, masses may be obtained of a size the limits of which we cannot assign. Finally, nearly all the movements of the apparatus may be accomplished by steam; the labor of the puddler has no counterpart; muscle is everywhere supplanted by skill; man ceases to be the beast of burden, and, assuming his truer sphere, observes, judges, and directs.