The Einhorn (Unicorn) Press

 

 

 

 

 

Electric arc furnaces came into extensive use in the early twentieth century, and General Electric Company’s G. E. 2250-LB model above was touted as “the most efficient and economical apparatus for melting non-ferrous metals and alloys” in a 1921 sales brochure.  It claimed that “by means of the G-E Electric Furnace the highest quality of product can be secured with a minimum loss of volatile alloys,” and that “working conditions are vastly superior to those where fuel-fired furnaces are used.”  This meant the workers were exposed to less heat radiating from the open fuel-fired furnaces, like the one below, where several workers are smoking on the job:

 

 

 

 

Beside better working conditions, electric arc furnaces were superior to fuel-fired furnace operations in several technical and economical ways.  They allowed for an accurate measurement and control of the temperature; freedom from contamination with oxygen, sulfur, and other products of combustion; accurate control of the composition of the alloy, reduction in loss of zinc by volatilization and oxidation.  Electric melting also reduced fuel cost, eliminated costly crucibles, reduced the cost of reclaiming metal from slag and ashes, while maintaining an ability to melt a large amount of metal in one heat.

 

The G. E. brochure pointed some distinctive features of the G-E electric melting furnace, in that its temperature was easily controllable, metal loss was particularly low, the atmosphere could be made neutral or reducing, and that its heat was uniformly distributed.  Additionally, the G. E. electric furnace could be forced for rapid melting if necessary, its bath was shallow and had a large surface area to rapidly absorb heat, and its hearth was readily accessible for charging and rabbling.  In regards to its electrical features, the brochure maintained that the power input could be automatically controlled, that it employed a balanced load from polyphase power lines without objectionable surges, and that the General Electric electric arc furnace had a high power-factor, 95 per cent.

 

 

 

 

With regards to the sectional view above, of the General Electric 2250 LB furnace for melting non-ferrous metals and alloys, the G. E. sales brochure specifically described the oven as follows:

“This G-E Electric Melting Furnace consists of a strongly built rectangular steel shell, lined with suitable refractory material. T he furnace is complete with motor-operated electrode and tilting mechanisms, and all electrical accessories, such as transformers, switching, and metering equipment, automatic electrode control, and pyrometer.

“Current may be taken from either a two-phase or three-phase line, and transformed to two low voltage, single-phase, two-electrode circuits.  Heat is generated in the trench at each end of the hearth, by arcs made between the electrodes and a bed of broken graphite piled on carbon wearing blocks, which in turn rest on cross electrodes.

“The heat is conducted through the bridge walls and is also reflected from the roof to the metal. The above diagram shows a sectional view of the Furnace.

“The furnace is suitable for melting practically all non-ferrous metals and alloys.”

 

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