Britannica
Sources used in this answer
How does smelting separate copper-bearing matte from slag?
Created from Britannica articles
using AI.
AI can make mistakes, so verify using Britannica articles.
copper processing
Molten copper being made into plates.
During the smelting of copper-bearing sulfide ores, the separation of matte from slag is achieved through chemical reactions involving a flux, typically silica or limestone.12
When the ore concentrate is heated to high temperatures (1,230–1,300 °C), it forms a molten pool at the bottom of the furnace. The process works as follows:1
- Chemical Reaction: Impurities, particularly iron and oxidized gangue minerals, react with the added flux to form a distinct, light, and fluid layer of slag.1
- Phase Separation: Because of the difference in density and chemical composition, the slag floats as a layer over the heavier, molten matte—a crude mixture of copper, iron, and sulfur.31
- Removal: Once these layers have settled, the slag is removed from the furnace, leaving the concentrated copper-bearing matte behind for further treatment in a converter.12
This separation is essential for removing a large proportion of impurity elements before the final refining stages.4