In reference to the manner of constructing the furnace, the majority are of the fixed type, the so-called Siemens-Martin furnace, designed at first by the. Messrs. Martin themselves, and having regenerators situated underneath the hearth, and the reversing valves on one of the small sides. In two or three steel works only can the Pernot furnaces be found, with a revolving circular basin or hollow hearth, or the Batho furnace, with a round hearth, supported by an iron plate, free underneath, and with round regenerators with plate-iron casing placed laterally and above ground.
The mode of working is usually the " scrap process." What is known as the "ore process" does not appear to be used in France. The combined use of scrap and bre, known as the " Landore process," is used only at the Alleyard Works. Professor Jordan states that the nature of the lining varies in the different works, and according to the description of materials used. Sometimes the lining is acid ; that is, it is made with sand, ganister, or siliceous puddle ; sometimes it is basic—that is, made with magnesia bricks or puddle (ac cording to the system patented in 1869 by Mr. Emile Muller), or with dolomitic bricks and blocks ; at other times the lining is neutral : that is. made with chrome ore (according to the Valton-Remaury process). When the lining is made with chrome ore, Messrs. Valton and Remaury state that no material is taken from the lining either by the molten metal or by the slag, so that no corrosion takes place, and it becomes possible to act on the metal either by scraps or by ores, or by various agents in such a manner as to effect a complete de phosphorization, and to produce various descriptions of steel.
Use of Aluminum to secure Sound ingots.—It has been found that the addition of a small quantity of aluminum to molten steel just before pouring into ingots has a beneficial effect in rendering the ingots sound. Mr. J. W. Langley, of Pittsburg, in a paper read at the meeting of the American Institute of Mining Engineers in 1891, says : The practice in pouring ingots is as follows : The aluminum, in small pieces of a quarter or half-pound weight, is thrown into the ladle during the tapping, shortly after a small quantity of steel has already entered it. The aluminum melts almost instantaneously, and diffuses with great rapidity throughout the contents of the ladle. The diffusion seems to be complete, for the writer has never seen the slightest action indicating want of homogeneity of mixture—all of the ingots poured from one ladle being precisely alike so far as the specific action of the aluminum was concerned. The quantity of aluminum to be employed will vary slightly according to the kind of steel and the results to be attained. For open-hearth steel, containing less than 0.50 per cent. carbon, the amount will range from 5 to 10 ounces per ton of steel. For Bessemer steel the quantities should be slightly increased, viz.: 7 to 16 ounces. For steel containing over 0.50 per cent. carbon, aluminum should be used cautiously; in general, between 4 and 8 ounces to the ton. Sir. George G. McMurtrie, president of the
Apollo Iron and Steel Co., has found that aluminum can be made to replace manganese, and has rolled ingots down to thin sheets by using one half-pound of aluminum per ton of steel.
The Hoerde Desulpkurizina Process.—Mr. J. Massenez, of Hoerde. Germany, read a paper at the London meeting of the Iron and Steel Institute, in 1891, describing a process adopted at his works of desulphurizing molten pig iron prior to its conversion into steel by the Besse mer process. We extract from this paper as follows : In the treatment of phosphoric pig iron, which is employed in the production of basic steel, it is not sufficient merely to conduct the molten pig iron in large quantities to the converter in a mixed condition ; but the problem here is to render the proportion of sulphur also independent of the blast furnace process to such an extent that the proportion of sul phur in the finished steel is so low that the quality of the steel is in no way influenced by it.
In order to effect satisfactory desulphurization attention has been bestowed on the fact that iron sulphide is converted by manganese into manganese sulphide and iron. If sulphureted pig iron, poor in manganese, is added in a fluid condition manganiferous molten pig iron, poor in sulphur, the metal is desulphurized and a manganese sulphide slag is formed. At Hoerde, the mixing and desulphuriziug apparatus holds 70 tons of pig iron and has the shape of a converter, moved by hydraulic machinery. An hydraulic pressure of 8 atmos pheres is sufficient to set it in motion. The vessel is provided with a double lining of fire bricks of the same quality as those used for the lining of blast furnaces. This lining is attacked only along the slag line, and does not require repair until it has been in use for some six weeks. The consumption of manganese is very low. Theoretically it is the quan tity required for the formation of manganese sulphide, and in practice it lies been found that this amounts to about 0.2 per cent. The proportion of manganese which the desulphurized pig iron coming from the vessel should contain is best kept at about 1.5 per cent. in order to render the desulphurization as complete as possible. It has been found that if highly sill phureted pig iron is poured from the blast furnace into the desnlphnrizing vessel, 15 to 20 minutes are sufficient to effect the desulphurization requisite for the steel process. The iron in the vessel remains sufficiently fluid for several hours. It has been found quite unneces sary to obtain heat by passing and burning a current of gas above the bath of metal. Daily analyses during a month at Hoerde of the desulphurized metal for the basic process gave results as follows : phosphorus ranging from to per cent. Manganese, to 2'07 per cent. ; silicon, Oil to ; sulphur, to the percentage of sulphur before desuiphurization being to 0'481.