ABSTRACT
A matte is a sulfide mixture prepared artificially from an ore by fusion. It separates as an immiscible phase from the other molten components of the ore, e.g., gangue minerals which form a slag. A matte can be formed from sulfide concentrates or oxide ores. In the first case, the concentrate is melted in the presence of proper fluxes. When the metal values are to be separated as a matte from an oxide or a silicate ore, sulfur has to be added in the elemental form, as pyrite, or as a mixture of pyrite and gypsum. A matte contains a small amount of free metals. Iron, the main impurity in matte is removed in two ways: Selective oxidation and selective oxidation and slagging. Selective oxidation and slagging is the method commonly used: the molten matte is subjected to controlled oxidation in the presence of siliceous fluxes so that FeS is selectively oxidized and slagged while the other.
