Journal of the Southern African Institute of Mining and Metallurgy
On-line version ISSN 2411-9717
BARKER, I.J. Some considerations on future developments in ferroalloy furnaces. J. S. Afr. Inst. Min. Metall. [online]. 2011, vol.111, n.10, pp. 691-696. ISSN 2411-9717.
This paper argues that the scale up of furnaces and the supply of electricity are going to be two major issues that will affect the ferroalloy industry in the near future, and that economic factors will drive this development. The most common type of furnace for producing ferroalloys at present is the submerged-arc furnace with three electrodes, fed from a three-phase AC electrical supply. The scale up of this technology has now reached a fundamental constraint, which is caused by the electrical reactance of the secondary circuit. If the economy of any further scale up is to be achieved in the future then a different technology will have to be used. The supply of electrical power in future is likely to become a more complex issue than it is at present. Existing submerged-arc furnaces tend to run at fairly steady loads, but the ability to swing the load under demand-side management may offer advantages, and may allow a furnace to obtain cheaper power from the organizations that supply this power. This will have to be counterbalanced against the nuisance factors incurred by having a varying load in the operation of the furnace. Various options are therefore discussed in this paper. The possibility of scale up of Søderberg electrodes is discussed, as well as the use of DC power and multiple electrodes. Some of the issues with load swinging are also examined. A particular scenario is also briefly presented to show that considerable further scale up of ferroalloy furnaces is still possible.
Keywords : submerged-arc furnace; plasma furnace; DC furnace; scale up; Søderberg electrodes; smart grid; demand-side management; load shedding.