Sulfidation Reaction of Metallic Copper in Flash Smelting Furnace Conditions

Flash smelting is the major primary heat treatment process in copper smelting. The overall reaction of the process is the oxidation of sulfide copper concentrates by oxygen-enriched process gas, which is complete in a few seconds at 1400–1600 °C. Various materials lead to other reactions, including reduction and sulfidation. An increasing amount of recycled materials is used in flash smelting furnaces to achieve greater materials conservation. However, the copper contained in recycled materials can have a negative impact on the process due to the risk of liquid copper penetrating to, and damaging the furnace refractory. In order to avoid this catastrophic incident, sulfidation of copper is desired so that it enters the bath as sulfide and not metal. This study focused on the sulfidation behavior of metallic copper under flash smelting furnace conditions to understand the opportunity and its limitations. The specimens of copper concentrate mixed with metallic copper were rapidly heated and quenched in a tube furnace. Argon atmosphere was introduced to eliminate oxidation and investigate the sulfidation mechanisms. In argon, the sulfidation of metallic copper proceeded faster than the complete sulfur evaporation from copper concentrate. Furthermore, oxygen was injected to simulate the flash smelting furnace conditions in which the exothermic oxidation reactions of copper concentrate occur, and sulfur is promptly oxidized to sulfur dioxide. Different sizes of metallic copper particles were used to study the effect of the surface area.