TRANSACTION PAPER

Towards electrode immersion control on Lonmin's no. 1 circular furnace

G.A. Georgalli^I; J.J. Eksteen^II; R. Bezuidenhout^II; B. van Beek^II; T. Goff^II

^IUniversity of Stellenbosch, South Africa
^IILonmin, South Africa

SYNOPSIS

A control philosophy to be applied by Lonmin to maintain constant electrode immersion in their no. 1 circular smelting furnace is put forward. This control philosophy is facilitated though a combination of thermodynamic models used to predict the slag composition and empirical correlations to estimate the furnace eometric factor as well as the slag conductivity. The model can determine the operating resistance setpoint required in order to maintain a desired electrode immersion as a function of the feeds to the furnace, slag level and temperature. If modifying the resistance setpoint cannot maintain the desired immersion without moving out of the furnace P-V-I operating envelope, the model can be used to determine the amount of slag modifiers (silica or lime) required to shift the slag chemistry back into a region where the immersion can be controlled though resistance setpoint manipulation.

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