STEEL, ELECTRICAL PROCESSES OF MANUFACTURE. Electrometallurgical processes for the manufacture of pig iron, steel and ferroalloys, have received profound attention from a commercial point of view during the years of this century. In fact, a commercial production of electric steels seems to coincide almost exactly with the opening of the 20th century, for we. have it as a matter of record that three days before its beginning Heroult delivered to Messrs. Schneider and Company, Creusot, France, a carload of electric steel bars. This is the first record we have of a commercial sale and delivery of such steel. Experiments were made and • basic patents covering different processes were taken out during the closing years of the 19th century. It is over 40 years, however, since Sir William Siemens constructed and patented an electric arc furnace which would melt steel. It is not recorded that he believed this laboratory furnace was the begin ning of the new industry, but whether he thought so or not he stated very clearly the reasons why electric furnaces should be su perior to other furnaces where the product is in contact with the products of combustion of carbonaceous fuel. The advantages of electric melting as stated by Siemens are, first, the degree of temperature is theoretically unlimited; second, the fusion is effected in a perfectly neutral atmosphere; third, the operation can be carried on in a laboratory without much prepa ration and under the eye of the operator; fourth, the limit of heat practically obtainable with the use of ordinary refractory material is very high, because in the electric furnace the fusing material is at a higher temperature than the crucible, whereas in ordinary fusion the temperature of the crucible exceeds that of the material fused within it. In short, he says that the function of electric melting is to *effect such reactions and decompositions as require for their accomplishment an intense degree of coupled with freedom from such dis turbing influences as are inseparable from a furnace worked by the combustion of carbona ceous materials?' The soundness of these conclusions as applied to commercial conditions have been amply confirmed during the past decade. It seems like the fulfilment of proph ecy, for they were overlooked and all but for gotten for nearly a generation until there arose a group of engineers and inventors in several European countries during the closing years of the last century who perfected various processes for doing in the mills what Siemens had done in the laboratory. The enthusiastic claims of these inventors were not received with much interest by the steel men, but the Canadian government displayed commendable foresight when it appointed a commission in 1903 to investigate these processes at first hand in Europe, and in their report in 1904 Professor Harbord, the metallurgist of the com mission, stated first °that steel equal in all respects to the best Sheffield crucible steel could be produced either by the Kjellin, Heroult or Keller processes at a cost considerably less than the cost of producing high class crucible steel," and second, °at present structural steel, to compete with Siemens or Bessemer steel, cannot be economically produced in the electri cal furnaces, and such furnaces can be used commercially for the production of only very high class steel for special purposes?' Even this opinion of a competent observer was not sufficient to overcome the conservatism of the crucible steel makers. The venerable crucible process had withstood the competition of Besse mer steel and of acid and basic open hearth steel, and it was only natural that the new arrival should be viewed with distrust.
At the time of this report the writer found it very difficult to accept Harbord's first con clusion except in so far as it applied to the induction type of furnace, in which at that time no purification of the charge was attempted, and to make a good steel one started with selected raw materials just as in crucible melt ing. The combination of melting and refining
in one operation did not appear promising, and such samples of steel as came under examina tion, both foreign and domestic, did not tend to change this opinion. Metallurgically considered, electric furnaces are of two kinds. First, the early melting furnaces analogous to the crucible steel process — for example, the earlier Girod or the Colby and Kjellin induction furnaces; and second, smelting or refining furnaces, such as the Keller or Heroult furnaces for either pig iron or steel. In furnaces of the melting type we must start with the best raw materials if we wish to produce the best steel. Furnaces of the second type may be used (a) for the electric refining of pig iron direct from the blast furnace; (b) for melting and refining cold pig iron and scrap; (c) for the direct reduction of iron from its ores with or without subsequent refining to produce steel; (d) the electric refining furnace such as the Heroult, may be used as an adjunct to the open hearth or Bessemer process, in which the preliminary melting and refining is done. Electrically con sidered, these furnaces include (a) arc fur naces, e.g., the Stassanno process; (b) -are resistance, e.g., Heroult steel process; (c) re sistance furnaces, e.g., the Keller, Harmet and Heroult pig-iron furnaces, in all of which there is a movable carbon electrode and the hearth constitutes a fixed electrode. These fur naces are especially suited to the reduction of Iron ore, the charge of ore, lime and coke constituting a resistance conductor betweeri the movable electrode and the fixed electrode. In the Gin process a current is passed through the melt itself, making use of the Joule effect. In the Girod crucible process we have what may be called a furnace of the superficial resistance type. The current does not pass through the charge itself. The furnace consists of a cru cible of refractory materials surrounded by a granular carbon resistance material to which the current is conveyed by solid carbon con ductors, and the whole device is enclosed in a refractory chamber of non-conducting ma terials for thermal and electrical insulation; the induction furnace invention is due to . A. Colby, but Kjellin, Schneider and others employed the same principle, in that the heating current is an induced one, generated in an annular bath of metal constituting a single turn-secondary of a step-down transformer, in the original Colby patents the primary windings of the transformer surrounded both the electro magnet and the crucible itself. In the Kjellin process the primary winding is close to one leg of the electro-magget and both are surrounded by the single-turn-secondary or crucible itself. It would appear that there might be an ad vantage in dividing the primary winding into two parts, one within and one without the crucible-secondary, in other words, in com bining the Colby and Kjellin constructions in the same furnace. In the limited space of this article only a few typical processes can be described illustrating some of the above-men tioned general principles of construction. The variety of details of construction are very numerous, but the underlying principles are not so numerous; in fact, while so-called new proc esses have been introduced frequently during the past 15 years, they do not constitute essen tially new discoveries, but differ only in details of application of the electric heating and of furnace construction.