Characterisation of a Real-World Søderberg Electrode

Abstract

Very little research on Søderberg electrodes has been published in the journal peer reviewed public domain. The main aim of this work is to characterise a Søderberg electrode that was cut off approximately 0.5 m below the contacts shoes of a submerged arc furnace. Additionally, the characterisation data can be used to verify if Søderberg electrode models accurately predict important electrode characteristics. The operational history (slipping, current, and paste levels) proved that the case study electrode was a representative specimen. The characterisation results indicated no significant electrical resistivity, degree of graphitisation (DOG), and bulk density changes from 0.7 to 2.7 m on the non-delta side (outward facing), while these characteristics changed relatively significantly on the delta side (inward facing) of the electrode. The area where the submerged arc would mostly like jump off the electrode had the lowest resistivity, as well as highest DOG and bulk density. No significant difference in porosity as a function of length below the contact shoes were observed; however, slight increases occurred near the perimeters. It was postulated that oxidation of carbon resulted in increased pore volumes near the electrode perimeter. No significant difference in compressive breaking strength was observed over the electrode area investigated.

A Review of Biocarbon Substitutes in Electrodes and Refractories for the Metallurgical Industries

“…Typical Söderberg electrode paste is composed of 70-80% selected calcined anthracites and petroleum cokes, graphite, and 20-30% coal tar pitch binder [30]. The coal tar pitch binders have softening points ranging anywhere from 65 to 134 °C [31]. At temperatures between the softening point and the baking isotherm, the rheological characteristics of the binder are important as the paste must evenly flow to fill the casing while at the same time segregation is to be avoided [31].…”