Interactions of sulfur-containing gas with magnesia-chromite refractory in nickel flash smelting furnace

Abstract

As-received and spent magnesia-chromite refractories from a nickel flash smelting furnace were analyzed and compared to shed light on the interactions between the gas phase and the refractory material, a topic that has not received previous research effort. Based on the results, process-originated gaseous sulfur-containing species, such as SO2 and SO3, played a key role in the refractory reactions. In the absence of a surface deposit, the hot end of the refractory underwent attack by SO2, resulting in sulfation of both the periclase and chromite phases, which has not been reported before. In the presence of a surface deposit, the sulfation of main phases in the near-surface regions did not occur, but sulfur-bearing species diffused deeper into the refractory material, where they reacted with MgO and CaO, forming MgSO4 and CaSO4. In addition to the detected sulfur penetration, impurity elements, e.g., As; K, and Pb, had diffused towards the cold end of the refractory. This suggests these elements could have entered the refractory as gaseous species and then condensed at low enough temperatures.