足尾事業所における銅製錬および副産物の製造

抄録

Ashio copper mine was discovered about four hundred years ago. Since Furukawa began the management in 1877, the whole amount of copper product reached 0.8 million tons until its closing in 1973.It served as the foundation of industrial development in Japan.
Copper smelting method has also been developed in Ashio according to the technology progress of the world. Mafuki Method and the blast or reverberatory furnace method were used from 1877 to 1956. Ashio Smelter was the pioneer of copper smelting in Japan. The newest method of the age could always be seen here.
The first flash furnace in Japan was adopted to Ashio Smelter in 1956. It has been given a lot of improvements continuously for 24 years to complete the original equipments suited to the flash smelting in Japan, and to establish a stable operation. Furukawa type flash furnace became famous throughout the world for its advancement in anti-pollution and energy saving properties, and high product ability in the large scale furnace. Flash furnaces are now adopted not only in Japan but all over the world. Furukawa has participated in planning and technical guidance of those furnaces.
In 1978, against the increase in energy cost, Ashio Smelter developed a new method for flash smelting in which oxygen enriched air is used. This saves a great deal of thermal energy.
The history of anti-pollution in Ashio is old. Neutralization ponds were equipped in 1892, and a plant for the wet type desulfurization of waste gas was built in 1897. The system of waste water treatment was especially improved to have a larger scale. Treated water here is quite clean and has been used as drinking water for more than twenty years.
The first electro-static precipitator, so called Cottrell, in Japan was built here in 1918, where arsenic oxide was started to produce. Today, arsenic oxide is also produced from waste acid water in the sulfuric acid plant by the special neutralization method. The flash roaster used here is the only one in Japan. Other by-products here are bismuth since 1923, Ashio Metal which is the alloy of Pb and Sn, Sb₂O₃, and etc.
The scale of Ashio Smelter is rather small but it is a unique inland smelter which has the oldest history and the best technology to use its own electric power plant.