The coastal Akita Zinc smelter, and switching feedstock from own mines to imported concentrate (1971)

The bottleneck named at the peak

What Arai Tomozo spent his time on in a 1965 lecture was not Uchinotai and Matsumine, the finest orebodies in Japan, but the fact that there were not enough furnaces to treat the copper and zinc coming out of them. A president who said the company “simply cannot digest” 36,000 tonnes of zinc a year was, six years later, building a new smelter on the coast. The starting point of that investment appears to lie exactly there — in flagging the downstream bottleneck as the critical issue at the moment when the ability to dig was at its peak.

That said, it cannot be read as evidence that an exit from mining was already envisaged in 1971. In the same year, at the Motoyama pit, ingenuity was still squeezing 70 tonnes of copper a month out of abandoned workings grading 0.3%; the effort to keep digging and the construction of plant to treat bought ore ran side by side. What survived was the latter. Equipment built on the decision not to limit feedstock to the company’s own mountains ended up as what supported the company after all domestic mining had ceased.