THE PNEUMATIC PROCESS OF MANUFACTURING STEEL AND MALLEABLE IRON BY THE BESSEMER PATENT IN ENGLAND.
The following extracts from a paper recently read before the Mechanical Section of the British Association by Henry Bessemer, on his process of manufacturing steel, will illustrate the subject fully, and present to our readers a clear exposition of the me chanical means now employed and the mechanical difficulties through which they were obtained:— "On the 13th of August, 1856, the author had the honor of reading a paper before the Mechanical Section of the British Association at Cheltenham. This paper, entitled `The Manufacture of Malleable Iron and Steel without Fuel,' was the first account that appeared shadowing forth the important manufacture now generally known as the Bessemer process.
"It was only through the earnest solicitation of Mr. George Rennie, the then Presi dent of the Mechanical Section of this Association, that the invention was, at that early stage of its development, thus prominently brought forward; and when the author reflects on the amount of labor and the expenditure of time and money that were found to be still necessary before any commercial results from the working of the process were obtained, he has no doubt whatever but that, if the paper at Cheltenham had not then been read, the important system of manufacture to which it gave rise would to this hour have been wholly unknown.
"The diagram shows in section the original fixed converting-vessel, as patented and erected in London for experimental purposes in 1856. It will be observed that the tuyers were passed through the sides of the vessel in a horizontal direction; the result was that the blast of air entered only a short distance into the fluid mass, and much of it escaped upwards between the sides of the vessel and the metal. The effect of this was the rapid destruction of the brick lining, caused by the excessive temperature generated in the process and the solvent property of the resulting silcate of protoxide of iron, which sometimes destroyed a lining of half a brick in thickness during the blowing of two charges of metal for about twenty minutes each. Another difficulty arose from the impossibility of stopping the process without running out the metal; for if the blowing ceased for one instant the fluid metal would run into the tuyers and stop them up.
"A great inconvenience of the fixed vessel also arose from the danger and difficulty in tapping out the fluid malleable iron with a bar, after the manner of tapping an ordi nary cupola-furnace; for the blast had to be continued during the whole time the charge was running out of the vessel, in order to prevent the remaining poitions from entering the tuyers. A similar difficulty arose while running in the crude metal from the melting-furnace, since it was necessary to turn out the blast before any metal was run into the vessel: the first portions so run in were, in consequence, partially decar bonized. before the whole of the crude metal had left the "These were among the more prominent difficulties that had to be remedied. It is, however, satisfactory to know that even in this its infant state the process and appa ratus were practically successful, in proof of which there is placed upon the table part of a malleable iron railway-bar made from pig iron, at Baxter House, by blowing air through it in the apparatus just described, the fluid malleable iron having been run into a 10-inch-square ingot-mould and the bloom so made rolled direct into the bar shown. The small malleable iron forged gun will serve as an example of the clear ness and freedom from cracks or flaws in malleable iron so made and forged under the steam-hammer. It is one of the early productions of the process, and, like the mal leable iron rail, was made wholly without any recarbonizing of the metal or the em ployment of spiegeleisen or manganese in any form whatever. Malleable iron so made from hematite pig iron is red short, like all other wrought iron made wholly from hematite; but that it is perfectly malleable and extremely tough when cold' may be seen on examination of the iron rope exhibited, which consists of four rods of 1-inch round iron twisted cold into a close coil. These bars extended 13 inches in length in 4 feet, and were reduced nearly inch in diameter in the operation of twisting, thus showing that malleable iron so made possesses an extraordinary degree of ductility.