Onahama Smelter introduced Mitsubishi technology for copper smelting process.
Copper concentrates(Cu: 30%, Fe: 25%, S: 30%) is fed through lance pipe with oxygen
enriched air into the smelting furnace then oxidized and melted by exothermic
reaction to form molten mixture of matte(Cu: 60%) and slag. All the molten materials
produced in S furnace are continuously transferred through covered launder which
links S furnace and reverberatory furnaces.
Copper concentrates is charged into reverberatory furnaces and melt by coal firing.
The molten materials from S furnace are charged into reverberatory furnaces and
separated into matte and slag. On the other hand, in the reverberatory furnaces, the
automobile shredder residue(ASR) is treated by incineration. The heat of
incineration helps to reduce fossil fuel consumption.
In the P.S. converters, silica flux is added to the matte from the reverberatory
furnaces, and blast air is injected through the tuyeres in order to separate iron and
sulfur from matte by oxidation. Then the white metal (Cu 75%) is further oxidized
with air and the blister copper is produced. The blister copper is 98-99% purity.
The molten blister copper is delivered to anode furnaces and refined to
anode copper after oxidation by air blowing and reduction by submerged
combustion of oil. Anode copper is usually 99.5% purity. There are two
types of anode casting machines; Anode casting wheel and Hazelett
continuous strip casting machine.