SMELTING ORES BY ELECTRICITV 



crucible. The primar3^ coil is insulated with mica and is 

 kept cool, by a jacket through which cold water is alwa5^s 

 circulating. The primar}^ is connected to the supply-circuit 

 delivering 90 amperes at 3,000 volts. It can be designed 

 for voltages up to 5,000 or 6,000 volts. A current is in- 

 duced in the charge which forms a single turn. Its iiitens* 

 ity is 30,000 amperes at 7 volts, and the C2R lo.ss pro- 

 duces the heat for smelting. The steel is tapped off from 

 the spout of the groove, but a certain proportion is always 

 left to maintain the secondary current. The temperature 

 of the steel when tapped is between 1,600 C. and 1,700 C. 

 The estimated cost of the production of a ton of steel b}' 

 the Kjellin process is $34. 



The advantages of this furnace are; i. It permits of 

 the use of high voltage direct on the primar}^ winding. 

 2. There are no cables, connections or electrodes in the 

 secondary. 



The disadvantages are: i. Very low power factor, 

 due to the wide separation of the secondary and primary, 

 and the low resistance of the secondary. 



In the Gin furnace, which is of the electrode type, the 

 trough in which the metal is held is doubled on itself sev- 

 eral times, so that there is formed a sort of huge incandes- 

 cent lamp, the gleaming molten metal forming the filament. 

 The Gin process cannot be successfully used for the extrac- 

 tion of iron from its ores ; but where electrical energy can 

 be produced at a low price, it can be successfully used for 

 the production of higher grade steel from pig iron. 



The Stassano process employs a furnace of the arc 

 type. In this process of the manufacture of steel or iron 

 by electricity, the charge is calculated beforehand, and in 

 the form of briquettes, is subjected to the radiation of heat 

 from an electric arc situated above the charge to be treated. 

 Nothing is added, so the calculations and output agree. It 

 is simply a matter of compounding the charge according as 

 it is desired to produce steel and iron. The furnace is 



