In Outotec® Fire Refining Process, blister copper is processed into anode copper and has two main stages – oxidation and reduction. The aim is high-quality anode copper to enable smooth casting and electrolytic refining operations.
Blister copper contains sulphur and other harmful impurities, which need to be removed before casting. In Outotec® Fire Refining Process, the blister copper is processed into anode copper, which has the necessary properties for casting into thin, strong, smooth anodes for the refinery. Fire refining is a two-stage process.
In the first stage – oxidation – most of the sulphur is removed. As a result of direct blister or flash converting process, the blister copper usually contains 1000–3000 ppm of sulphur. After oxidation, the sulphur level is typically decreased to 100–300 ppm. Some slag also forms at this stage, and slagging is usually done at the end of oxidation.
In the second stage – reduction – the oxygen level of the anode copper is adjusted to an optimal level for electrolytic refining. After reduction, the target oxygen level is between 500–1500 ppm. During reduction, the final anode copper sulphur content is also decreased to a target level below 50 ppm. Final target levels of impurities, sulphur and oxygen are subject to a thorough optimization process, where converting, fire refining, anode casting and electrolytic refining are all considered.
Copper scrap from the refinery and in-house anode copper scrap can also be melted in the anode furnaces. Scrap melting capacity can be tailored according to each customer’s specific needs.
As a result of Outotec’s smelting and refining processes, know-how and close co-operation with Kennecott Utah Copper, Outotec® Anode Furnaces can be designed to take account of customer needs in a holistic way. This is reflected by the furnaces’ detailed design, off-gas treatment, process optimization, process control, project implementation and customer personnel training. As a result, customers will have a reliable and cost-effective process solution.