The Kosaka mine in Akita, the place where we started, produced ore called “earthy ore” which contained a lot of silver. After 1890, the depletion of the ore began, and also the adaptation of the gold standard made the price of silver plummet. As a result, the mine was in danger of being closed. As a consequence, we switched our mining and smelting target ore to the abundant “black-ore”, found in the deeper area than that of the “earthy ore”.
While black ore is rich in useful metals including gold, silver, copper, lead, zinc and rare metals, it is difficult to separate them because the many impurities the ore contains. Even now, it is said that this ore is difficult to smelt. With the underdeveloped technical abilities at that time, only a small part of the ore could be used, and it was thought to be impossible to commercialize it.
In 1902, amid calls for the Kosaka mine to be closed, DOWA’s engineers succeeded in developing a unique and innovative smelting method that was called the “pyritic smelting method”. It is said that the success of the pyritic smelting method opened up a way after that for the continued development in Japan of the copper blast furnace smelting method.
Due to the development of this technology, the scale of production was gradually expanded with such things as the construction of a large blast furnace by Kosaka Smelting & Refining, establishing it as one of the leading copper smelters in Japan. Furthermore, while expanding the smelting business to such things as gold and silver, this greatly contributed to the economic development of Japan, and in 1907 we recorded the country’s largest amount of production. After that, with further research of smelting methods and improvements, in 1952 we established a wet smelting technology that included sulfatizing roasting, leaching and the electrolysis method to efficiently extract copper and zinc from black ore, with the aim of making full use of black ore.
With the changing times, in 1990 mining at the Kosaka mine (Uchinotai) came to an end, but the smelting technology that started with black ore has been inherited by the current metal recycling of DOWA.

With the change from the Showa era to the Heisei era against a background of more and diversified waste, and the depletion of resources for various reasons, society started to change to one that was recycling oriented in order to effectively use resources as long as possible.
Across the four eras from Meiji to Heisei, Kosaka Smelting & Refining advanced together with the development of Japanese industry, and it has greatly transformed itself to meet the changing needs, from ore-based smelting to a “recycling smelter” that again removes metals from used electrical and electronic products.
Since the quality of the recycled raw material is not uniform, this transformation has not been easy, but just like we faced the challenge of black ore smelting amid the danger of the mine closing, we have overcome various problems with the power of technology, transforming one smelter into one of the few recycling smelters in the world that has the technology to recover many kinds of metals.
From April 2008, with full-scale operation of a new type of smelting facility that can handle recycled raw materials, we have made it possible to recover more than 20 kinds of elements, such as precious metals like gold or silver, and rare metals such as selenium, antimony and bismuth, by using raw materials like printed circuit boards from mobile phones and used home appliances, and residue from the DOWA Group’s zinc smelting process.
In addition to the recovery of diverse metals, it can be said that a major feature of DOWA’s recycling is the stabilization of harmful substances. As we cultivated our mining business over many years, we established unique processing methods to handle the black ore with its many impurities. By striving to avoid both atmospheric and water pollution, and building technology to reduce the impact on the environment, in addition to recycling, we began new environmental business field such as soil remediation and safe treatment/disposal of waste.
Currently, the DOWA Group’s recycling-related companies in Akita Prefecture form a cooperative environmental complex. Kosaka Smelting & Refining in the Kosaka district is the core of this complex, with Eco-Recycle Co., Ltd. in the Hanaoka district of Odate doing household appliance recycling, and recycled raw materials accepted from Akita Zinc that is located in the city of Akita on the coast.
At the same time, we are minimizing the impact on the environment by completing within the area detoxification treatment and landfill.
Just as we in the DOWA Group have created new value until now by responding to crisis and change, we would like to continue to respond to the various expectations and requests of society with the power of technology.