Mitsui Mining & Smelting
Corporate History & Strategy

The yen appreciation following the 1971 Nixon Shock diminished the international competitiveness of mining operations within Japan. Mitsui Mining & Smelting also faced the management challenge of deteriorating profitability in its domestic non-ferrous metal mining and smelting operations. However, since Mitsui Mining & Smelting operated the Kamioka Mine—one of the world's leading zinc-producing mines—it held a relatively advantageous position compared to competitors' domestic non-ferrous metal mines. As a result, the decision to downsize the Kamioka Mine was delayed by several years compared to competitors.

As of the end of March 1975, 2,284 employees were engaged at the Kamioka mining operations, and the transfer or reduction of this workforce became a critical management issue. The delay in the closure decision was also attributable to management's prioritization of employment preservation, opposition from labor unions against dismissals, and consideration for the municipalities surrounding Kamioka. There were no industries in the vicinity of the Kamioka Mine capable of absorbing the workforce, making mine closure a matter directly impacting the local economy.

In 1978, Mitsui Mining & Smelting decided to downsize the Kamioka Mine. At this point, the policy adopted was not complete closure but rather gradual downsizing through production cuts and headcount reductions. Workforce reductions of several hundred were implemented every few years, progressively scaling down the mine's operations. However, the reductions proved insufficient, and the further yen appreciation following the 1985 Plaza Accord worsened the business situation.

In 1986, Mitsui Mining & Smelting separated the Kamioka Mine into a wholly owned subsidiary, 'Kamioka Mining & Smelting Co., Ltd.' Gradual scale-downs of production and workforce continued thereafter, including the cessation of lead refining from ore in 1994 and a 20% workforce reduction in 1995. In June 2001, Mitsui Mining & Smelting decided to close the Kamioka Mine by ceasing ore extraction, concluding approximately 130 years of mining operations since Mitsui-gumi's acquisition of the Kamioka Mine in 1874.

After the mine closure, Kamioka Mining & Smelting pivoted its business to 'recycling-based smelting, hydroelectric power generation, and utilization of underground facilities.' While ore extraction was discontinued, the company transitioned to a structure leveraging its smelting facilities and technical expertise for lead recycling and the manufacturing and sale of non-ferrous metals. Having ended its role as a mine, Kamioka Mining & Smelting continued as a smelting-centered business entity.

As of FY2024 (ending March), Kamioka Mining & Smelting operates as a wholly owned subsidiary of Mitsui Mining & Smelting with 525 employees, recording revenue of 43.5 billion yen and operating profit of 6.1 billion yen. In an environment of surging international non-ferrous metal prices, the business has maintained strong performance, continuing to function as a profit-generating entity driven by recycling-based smelting and favorable metal market conditions even after the mine closure.