| The Bessemer process of steel making was the | | | | distributed, by means of a ladle, into heated |
| first low cost industrial process for the | | | | revolving cylinders, called ballers, and when it had |
| mass-production of general steel ( from molten | | | | solidified in balls, it was taken to a squeezer, and |
| pig iron. Its inventor, Henry Bessemer, took out a | | | | afterward given a wash heat, and then worked |
| patent on the process in 1855. The process was | | | | down as usual into the desired product. Flohr adds |
| also independently figured out in 1851 by William | | | | (basic process) briquets of iron ore, scale, etc., |
| Kelly. The process had also been used in other | | | | bound together with about 10% of slaked lime, |
| countries for hundreds of years, but not in | | | | and claims that thereby the slag is made thinner, |
| industrial use. The primary principle involved is | | | | and the dephosphorization much more rapid. |
| removal of impurities from the iron by oxidation | | | | Harmet's process consists in treating the molten |
| through the use of air being forced through the | | | | pig, first in an acid vessel to eliminate the silicon, |
| molten iron. The oxidation also raises the | | | | and then in a basic vessel to remove the |
| temperature of the iron mass and maintains it's | | | | phosphorus and the remaining impurities, care |
| molten state. | | | | being taken that none of the silicious slag from |
| The Basic Bessemer process: A certain amount | | | | the first vessel goes into the second; this is also |
| of lime is charged with the iron, and the process | | | | termed "repouring" process, or transfer process. |
| is conducted in practically the same way as the | | | | The Massenez modification of the basic process |
| acid until the flame drops. Here, instead of turning | | | | for treating high silicon metal consists in charging |
| the vessel down, the blowing is continued | | | | only part of the lime at the commencement of |
| (sometimes a little more lime is added) for about | | | | the process, and when the carbon flame appears |
| four to five minutes, during which time the | | | | (showing the silicon has been eliminated) as much |
| phosphorus and some of the sulphur are | | | | as possible of the slag is poured off; the balance |
| removed. The end of the operation is determined | | | | of the lime is then added, and the blowing |
| by taking a test ingot which is forged down, | | | | completed. In Pettitt's process (basic) iron oxide |
| quenched in water, and broken; the fracture and | | | | was used to effect the removal of the |
| also the malleability indicate the state of the | | | | phosphorus, irrespective of the lining of the |
| process. The period before the drop of the flame | | | | converter. Rochussen and Daelen's process |
| is called the fore blow, the latter one the after | | | | consisted in charging rich iron ore into the |
| blow (rarely over blow). When ready, the vessel is | | | | converter (acid) with the molten pig, and in lining |
| turned down, as much as possible of the slag | | | | the converter with it previous to the blow. The |
| poured off, and the metal decarburized in the | | | | claim was made that the amount of blast required |
| vessel or in the ladle. As a small percentage of | | | | was largely diminished while the amount of steel |
| phosphorus always passes back into the metal | | | | was increased, but the excessive corrosion which |
| from the slag, the heat must be blown down, i.e., | | | | must take place would more than offset any |
| the phosphorus reduced to a lower percentage | | | | such advantages. Schiebler's process consists in |
| than that required in the steel. A heating takes | | | | charging the metal and part of the lime in the |
| about 20 to 25 minutes, and one vessel can | | | | vessel, and both the metal and slag are poured |
| produce about 1000 to 5000 tons per day, | | | | out when the first or phosphoric slag is formed. |
| depending on the size, which varies from about 15 | | | | The treatment is completed in a furnace having a |
| to 25 tons | | | | basic or a neutral hearth, with the addition of the |
| Modifications of the Bessemer process have been | | | | balance of lime or flux. |
| concerned almost entirely with basic practice, as | | | | In the United States, commercial general steel |
| will be seen below. The Champin pneumatic | | | | production using this method stopped in the late |
| process was a modification for making wrought | | | | sixties. It was replaced by processes such as the |
| iron of which the advantages would appear to be | | | | Linz-Donawitz process, which offered better |
| very doubtful. Pig iron was blown in a converter in | | | | control of the final chemistry of the steel. |
| the usual way, and the blown metal was then | | | | |