Evaluation of Coke Resistivity for the Manganese Alloy Market

Abstract

Southern Africa hosts some of the largest manganese reserve in the world. The production of manganese alloys is of strategic importance to the economies of the region. The submerged arc furnace has become the equipment of choice to produce manganese ferro-alloy both locally and internationally. Furnace operators aim to reduce the cost of production by better understanding the role played by the various raw materials involved in the processes. Coke is one of the key raw materials fed into the SAF, it plays three key roles in electric furnaces. Coke is a reducing agent; it is a source of carbon found in the alloy; and it also acts as a resistive element facilitating heat generation in the electric furnace. The heat generated plays two key functions in the furnace; ensuring both the metal and the slag have sufficient viscosity and it provides the heat required to support endothermic reactions. This study investigated ambient temperature and high temperature resistivity characteristics of coke made from single source coals. Measurement of coke resistivity was performed using the four-point technique. The results showed a statistically significant difference of mean resistivity between coke. It was observed that coke resistivity generally decreased with increasing temperatures. Raman spectroscopy was used to showed that the structural order of coke changes with increasing temperature.