A Study on the Temperature Dependency of the Electrical Conductivity of Chromite Pellets

Abstract

In ferrochrome production, the main feed materials of a submerged arc furnace (SAF) are chromite pellets, coke, and upgraded lumpy ore. The electrical behavior of the feed material in an SAF is important since it has an impact on the functioning and productivity of the furnace. Ideally, the electrical conductivity should be low in the upper part of the furnace and high near the electrode tip to ensure that the electric current path is through the metal bath via arching. An alternative option for the current path would be by ohmic conduction through the solid feed, but in this case, heat energy will be mostly wasted. This study focuses on the electrical behavior of chromite pellets as a function of temperature. To this end, the electrical conductivity of a chromite pellet bed was measured in an inert atmosphere from room temperature up to 1500°C. The electrical conductivity was measured both during the heat-up and cooling of the samples. It was found that the electrical conductivity increased continuously until the maximum temperature of 1500°C and was generally higher in the cooling cycle than during the heat-up at the corresponding temperature.

Keywords: submerged arc furnace, chromite pellet, electrical behavior