MMC Magazine

The increasing demand for copper along with the development of heavy industry during the Taisho Period (1912-1926) created an urgent need for a central refinery that could process ore brought in from mines around the nation. The coastal area of the Inland Sea, where many copper mines were located, satisfied the environmental requirements for refineries. Noshima Town in particular was enthusiastic about hosting this fundamental industry, but a major priority for the town was employing cutting-edge technology to prevent smoke and other environmental pollution. Thus began the history of environmentally friendly refineries developed under the leadership of Mitsubishi’s 4th president, Koyata Iwasaki.

Naoshima Smelter & Refinery produced a wide range of products, including crude copper, crude lead, sulfuric acid, electrolytic zinc, cadmium and germanium until the early Showa Period. In 1939, the refinery’s reverberatory furnace was upgraded to increase the production of crude copper from 300 to 1,000 tons per month. Operation ceased with the end of the war in 1945, but raw copper production restarted two years later. By 1952, the production of copper recovered to 1,000 tons, and reached 3,000 tons within five years.

Since the high economic growth in Japan had cooled and domestic mines had been closing one after another, the copper refinery business found itself under pressure. It was against this background that Mitsubishi Mining Company Ltd. built a new copper smelter in 1969. The smelter had the 2nd reverberatory furnace with an electrolytic copper production capacity of 7,500 tons, a copper electrolysis plant, a sulfuric acid plant, a general office and a transformer substation (present-day Chugoku Electric Power Co., Inc.) comprising the foundation of the facility that has continued operating to the present day. Through large-scale investment in facilities and equipment, crude copper production more than tripled from the 54,000 tons that had been produced the year before.

It had been the dream of engineers to combine a series of processes into an integrated system, from the preparation of raw materials to the production of copper, since the time of King Solomon, the Biblical ruler who oversaw the birth of copper refining about 3,000 years ago. In 1974, Mitsubishi was the first in the world to introduce a continuous copper production method with an integrated refining system into practical operation. Takeshi Nagano, who would later become the first Chairman of Mitsubishi Materials Corporation, took the initiative in establishing the method. Having overcome difficulties brought on by an oil crisis, which caused delays in plant construction, they succeeded in establishing a world-class pollution-free and highly efficient method of copper production.

In 1989, a precious metal plant with the largest capacity for gold production in the Orient was built. This made possible the integrated production of not only for copper, but also for precious metals. In 1991, a new, highly productive continuous copper refining furnace integrating a continuous copper refining furnace and a reverberatory furnace was built. The plant established the production methods for the company’s current major products – electrolytic copper, precious metals, sulfuric acid, plaster and crude nickel sulphate. During the Heisei Period, however, it was discovered that large amounts of industrial waste had been illegally dumped by a disposal company on Toyoshima, an island neighbouring Noashima.

The amount of industrial waste, totalling more than 900,000 tons, was dumped illegally by the disposal company over a period of 16 years. The Naoshima Smelter & Refinery decided to give its full cooperation to Kagawa Prefecture to facilitate the intermediate processing of the waste. At the same time, Mitsubishi Materials started its waste recycling business to process materials such as shredder dust. At present, the processing capacity for scrap such as circuit board waste containing valuable metals (E-Scrap) is among the world’s highest. Not only is the facility a major source of income within the metal business, but it is also an important step that Mitsubishi Materials has taken toward creating a sustainable society.