This article was originally published in Electrochemical and Metallurgical Industry Publication of January 1907. Information within this article is therefore correct as of 1907. The publication of this material aims to provide historical insight on the subject and its place in industry.
The ingenious and interesting crucible furnace devised by M. Girod and already described in this journal (Vol. II., p. 309), has been abandoned so far as its application to the manufacture of steel is concerned. On the other hand, a furnace has been constructed and submitted to the test of extensive use which seems destined to play a not unimportant part in the inevitable extension of manufacture of steel by electrical heating processes.
This furnace is of the arc type and is characterized by the fact that it employs a single vertical electrode. The arc furnace is maintained between this electrode and the slag which covers the metal contained in the hearth of the furnace. The molten metal is connected to the other pole of the dynamo by means of a series of water-cooled steel bars sunk in the refractory lining of the base of the hearth.
The process of treatment is in general similar to that adopted in the Heroult furnace; the superposed layers of slag being of such a composition as is required for the refining or carburization of the metal, and being renewed from time to time to assist in these processes.
Extensive trials have already been affected, notably by one of the leading French steel works, which has been utilizing the equipment at Ugine for the manufacture of special steel for the construction of small pieces of armor plate, etc.
So far as can be seen the power expenditure is quite favorably low; and the possibility of eliminating the injurious constituents from the low-grade steel charged into the furnace offers no more difficulty than is the case with those furnaces which employ two electrodes arcing into the slag.
In the simplicity of the design and in the ease with which automatic regulation can be effected, the present furnace is certainly of considerable interest.
In the annex of the works in which this steel plant has been erected, M. Girod is also employing one of his resistance furnaces as a re-heating furnace for small steel ingots. The heating chamber of one of his multiple crucible furnaces contains the ingots to be heated, the chamber itself being surrounded by the resistance material, consisting of ferro-silicon and carbon. This type of reheating furnace is certainly worthy of consideration, for in few applications of fuel heating is the waste of coal so enormous as in the old-fashioned reheating furnaces still so largely employed in the steel industry.
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