In the smelting and refining business, we produce refined copper with purity of 99.99% or higher from copper concentrates with around 30% copper purity. As byproducts of the copper smelting and refining processes, gold, silver, and other precious metals are produced, as well as products such as sulfuric acid.
In Japan, we have formed an alliance centering on Pan Pacific Copper Co., Ltd. (PPC), a joint venture with Mitsui Mining & Smelting Co., Ltd., which has the top smelting and refining capacity in Japan.
We also have a comprehensive business partnership with LS-Nikko Copper in South Korea, a company in which we hold 39.9% share. Together, the two companies boast copper production capacity that is among the highest in the world.
By taking advantage of the merits of scale in raw materials procurement and product sales as well as pursuing efficiency at smelting and refining facilities while ensuring safe and stable operation, the Group aims to strengthen our competitive edge even further.
See Nonferrous Metals and Chemical Products for details.
The Flow of Smelting and Refining Processes
The copper concentrates offloaded from ships are carried to stockpile domes, where they are sorted into different types for storing. Multiple types of copper concentrates are mixed together and sent to a flash furnace.
2.Flash furnace process
The copper concentrates are blown into a flash furnace along with oxygen enriched air. An instantaneous oxidization reaction inside the furnace causes the copper concentrates to melt from the combustion heat. Copper matte with a grade of 65% is then separated from slag consisting of iron oxide, silicate, and other components.
3.Converter furnace process
The matte created in the flash furnace goes to a converter furnace. Oxygen enriched air is blown into the converter furnace and the copper matte is oxidized, becoming blister copper with a grade of approximately 99%.
4.Anode furnace process
In an anode furnace, butane gas is blown in as a reducing agent, removing the oxygen from the blister copper to raise the grade to 99.3%. The resulting blister copper is cast in a casting machine into anode plates for the electrorefining process.
The cast anode plates are alternated with stainless plates as cathodes in electrolysis tanks filled with copper sulfate solution, and a direct current is introduced into the solution. The copper portion of the anode plates is dissolved in the copper sulfate solution and migrates to the cathode plates, to which it adheres. After about 10 days of electrolysis, the cathode plates are removed, the copper portion is stripped from the plates, and the final product is shipped as refined copper with a grade of 99.99%.
Keywords for Better Understanding the Metals Business
A Global Leader in Production Scale and Competitive Strength
By actively engaging in business alliances, we have maintained production capacity that is among the top globally. By seeking the merits of scale in raw materials procurement and product sales, as well as ensuring safe and stable operation at smelting and refining facilities while pursuing efficiency, we are aiming to strengthen our competitive edge even further.
- Figures correspond to refined copper production capacity levels.
Worldwide trends in refined copper consumption
Against the background of economic growth by China and other emerging nations, worldwide consumption of refined copper is increasing each year, raising demands for stable supply.