In the case of manufacturing the steel with electric furnace the consumption of electrodes takes a considerable portion in the total expenses. According to the statistical examination in our works during these 3 months, the manufacturing cost is made up on the average in the following percentages.
Raw materials 50.63%
Fusing materials etc. 10.74
Electric power 30.69
Electrode 7.94
With the view to establishing a more definite idea of the electrode consumption in the technical and economical points of view, the author carried out a series of observation in the practical works with natural and artificial graphite electrodes. The furnace which was at his service was Heroult type of 2 ton capacity. The results of the observation are summerised as follows:
1. So far as the amount of carbide is small in the reduction slags, the absorption of the carbon by steels in the refining process is less possible for the artificial graphite electrodes than for the natural. Whereas the difference between the both becomes unsignificant when the carbide contents int he slags grow larger.
2. For the purpose of manufacturing the steel of lower carbon contents the electrode of artificial graphite is certainly superior to those of natural grahite. For manufacturing the casting steels in general, however, the quality of the electrodes is quite unimportant.
3. In the case of the steel casting the composition of the slags may be selected as desired independent of the quality of the electrodes, i. e. the electrodes do not effect the composition of the resulting casting steels.
4. The comparison of the artificial and natural graphite electrodes of the same diameter makes it indeed certain that, the artificial graphite electrodes are less consumable than the natural graphite electrodes. However, if one takes the higher cost of the former into account the merit does not overcome the demerit. Artificial graphite electrode of 7″ dia. is less consumable than that of 3″ dia., but more expensive than the natural graphite electrode of 8″ dia., and moreover the working time is prolonged.
5. In order to compare the relative merits of electrodes, one must especially take the difficulty of handling, the frequency of breaking, the difficulty of controlling electric current, the utilization of electric arc, the influences upon the refractory materials of the furnace etc. into account.
