2716 



Chapter 22 



ORE 



WOOD CHIPS 



COKE 



COAL 



GASES 



t 







??:' 





CARBON ELECTRODES 





Wi 



CHARGE 



MOLTEN METAL 



ALLOY METAL IS 

 TAPPED FROM BOTTOM 



Figure 22-67. — Diagram of a submerged-arc electric furnace. The ore, wood chips, 

 coke and coal — introduced at the top of the furnace — are mixed in varying propor- 

 tions to produce the alloy desired. (Drawing after Wartluft 1971.) 



Annual demand. — The electrometallurgical industry consumed about 

 796,000 tons (green weight) of wood in 1970 — about enough to operate a 500- 

 ton-per-day pulpmill for a year. In 1970 59 percent, 480,000 tons, was con- 

 sumed by plants in the Ohio and Tennessee River Valleys (fig. 22-69). 

 Consumption varies from 6,000 to 78,000 tons per plant per year. Average 

 annual consumption per plant is 36,000 tons. In 1970, bark residues represented 

 about 5.3 percent of the total amount of woody reductants consumed. Of these 

 bark residues, 30,400 tons (green basis) were hardwood bark and 12,000 tons 



