PERPENDICULAR SECTIONS OF CONVERTING VESSEL.
FIG. 3.
OUTSIDE VIEW OF CONVERTING VESSEL.
A process has lately been invented by Bessemer to supersede the long and laborious process of “puddling.” It consists essentially of transferring the melted iron into a vessel in which there are tubes inserted at the lower part, and through which air is forced at a great pressure, which bubbles up in streams through the melted metal, and, as it does so, unites with the carbon and sulphur of the iron, converting them into carbonic and sulphurous acids, and at the same time producing an increased heat, which is quite necessary to the success of the process, for as the iron becomes purer it also becomes more difficultly fusible, and would set into a solid mass, but that this greatly increased temperature keeps it fluid. This rising of temperature is similar to what takes place upon blowing a common fire with bellows; for the more air that is admitted to carbon raised to a very high temperature, the more rapidly does it combine with its oxygen, or, in other words, the more rapidly does it burn. So that, in this process of Bessemer’s contriving, the carbon of the iron acts as fuel to keep up the heat necessary to maintain its fusion, and at the same time, by being converted into carbonic acid, escapes in bubbles (like the bubbles which escape from soda-water), and this rapid production of gas in every part of the fused iron also assists in bringing about a thorough stirring-up and mixing together of all its parts. Reference to the accompanying diagrams will illustrate the working of the process. In [figs. 1] and [2], A B are lower chambers, C is the melted iron, D is an upper chamber for melting scrap-iron, &c., E in [fig. 1] and D in [fig. 2] are openings for the escape of gas and flame, F F is an air-passage running all round and communicating by G with the tuyere-holes shown at E in [fig. 4], H is the fire-brick lining to the furnace, and I the tapping-hole through which the fluid iron is discharged. In [fig. 3], I is the tapping-hole, K the main air-tube leading from the blast-engine, L L perpendicular tubes (marked G in [figs. 1] and [2]) leading from circular air-passage to tuyere-holes, M is an opening for the insertion of iron into the upper chamber, opposite to opening D in [fig. 2], and N the tap for regulating the blast; O indicates the outer casing of wrought iron.
When the process is carried only to a certain point, the result is a sort of semi-steel, which the inventor of the process expects will be a very useful article of commerce.
FIG. 4. HORIZONTAL SECTION OR PLAN OF CONVERTING VESSEL.
During the bubbling up of the whole mass of iron and the extreme elevation of temperature caused by the union of the carbon of the impure iron with the oxygen of the air, the oxide of iron as fast as it forms fuses into a sort of glass, and this unites with the earthy matters of the impure iron and floats on the upper part as a flux, thus ridding the cast-iron of all its impurities, with no other fuel than that contained in the iron itself and the air.
The accompanying illustration represents a horizontal section or plan of the converting vessel; A the central chamber, B a lining of fire-bricks, C the main air-tube, D the tapping-hole, E the tuyere-holes through which the air is forced into the melted iron to be purified, F is the outside casing of wrought-iron.