Mitsubishi Materials Ends Partial Onahama Smelter Operations

By:UA Finance

March 25, 2026

On Wednesday, March 25, 2026, Mitsubishi Materials decided to stop processing copper concentrate at its Onahama plant by the end of March 2027 due to declining treatment charges and tougher overseas competition squeezing profitability.

Mitsubishi Materials to Stop Partial Operations at Onahama Smelter

Mitsubishi Materials confirmed plans to halt copper concentrate processing and suspend associated smelting facilities at its Onahama plant in Fukushima by the end of March 2027. A sharp drop in treatment and reefing charges (TC & RCs) and intense global competition have eroded margins; however, the electrolytic refining plant and recycling facilities will remain operational while others are restructured to improve profitability.

Mitsubishi Decision Comparison Table

Aspect	Current Partial Operations (pre-2027)	Post-2027 Plan
Cooper Concentrate Processing	Active but Under Cost pressure	To Cease by March 2027
Smelting Facilities	Operational	Associated Smelting Equipment Suspended
Electrolytic Refining	Ongoing	Continues post-2027
Recycling & Ingot Production	Operating	Continues After Restructuring
Impairment Cost Impact	Limited	¥21B Expected Loss
Strategic Direction	Traditional Smelting Focus	Shift Towards Revenue Stability & Recycling

What it Means to Mitsubishi and the Metals Sector

The partial shutdown at the Onahama Mitsubishi plant underscores global smelting cost pressures and shifting profitability drivers. Aiming to adapt to market realities, improving long-term financial stability in metals and materials by focusing on refining and recycling.