Copper matte converting is a crucial intermediate step in the pyrometallurgical copper refining process. Its main purpose is to remove impurities such as iron and sulfur from the intermediate product—copper matte—produced in the previous stage, through oxidation, thereby obtaining crude copper suitable for further refining. This process is typically carried out in a horizontal converter (also known as a PS converter), by blowing air or oxygen-enriched air into the molten copper matte.

The entire converting process has distinct stages, mainly divided into the slagging stage and the copper-making stage. In the first stage, the slagging stage, ferrous sulfide (FeS) in the copper matte is strongly oxidized, generating ferrous oxide (FeO), which then reacts with the intentionally added quartz flux to form slag mainly composed of fayalite. This slag is periodically discharged, leaving a melt mainly composed of cuprous sulfide (Cu₂S), which is called white metal.

Then the copper-making stage begins. At this point, the cuprous sulfide in the white metal begins to be oxidized, generating cuprous oxide and sulfur dioxide. Subsequently, the unreacted cuprous sulfide reacts with the generated cuprous oxide, ultimately reducing it to metallic copper.

The products of the converting process are mainly three: first, crude copper, which will be sent to the anode furnace for the next refining process to ultimately produce anode plates for electrolysis; second, converter slag, which, due to its high copper content, is usually returned to the smelting process to recover valuable metals; and third, a large amount of high-concentration sulfur dioxide flue gas, which must be efficiently collected and treated and sent to the acid production system to produce sulfuric acid, thus achieving the recovery of sulfur resources and environmental protection.

Copper matte converting not only completes the qualitative transformation from copper matte to crude copper but also achieves efficient copper enrichment and impurity separation through its precise stage-by-stage control, making it an indispensable core link in modern copper smelting technology.