Applications in the Metal Processing Industry

Electrodes for the Production of Electric-Arc Steel. As shown in Table 5.11, the production of electrodes for steel eind aluminum processing is the largest application of molded graphite, in terms of both tonnage and dollars. As mentioned in Sec. 1.1, electrodes are one of the original applications and have been manufactured with essentially the same process for almost a century. 

The largest use of these electrodes is in the production of steel in electric-arc furnaces, mostly for the reclamation of ferrous scrap.l l These electrodes must have good electrical conductivity, good refractory properties, and low cost. Th gradually erode in use and attimes break altogether and must be replaced at regular intervals. 

The worldwide production of steel is slowly increasing, but the production of electric-arc furnace steel is increasing at a more rapid rate. This rate reached 28% of total production in 1990 as shown in Fig. 5.11. The major producers by area are Europe, North America, and Japan. 

This reduction is the result of two factors (a) improvements of the properties of the graphite materials, particularly a considerable reduction of the thermal expansion and resulting increase in thermal-shock resistance, and (b) improvements in arc-furnace operating techniques. 

Electrodes for Aluminum Production. Aluminum is processed electrolytically and the production of the necessary electrodes is the second-largest application of molded greiphite (see Table 5.11 above) The anodes are similar to those used in electric-arc steel production and are also manufactured from petroleum-coke filler and coal-tar pitch. The aluminum collects at the cathodes which are large blocks lining the electrolytic cell. These cathodes were originally made of baked carbon based on anthracite coal but, in recent years, have been upgraded and are now made of molded graphite from petroleum coke. 

---