Century Aluminum Mt Holly Smelter Expansion Lifts US Primary Aluminum Output

Century Aluminum

Century Aluminum Mt Holly smelter production has begun from the company’s expansion project in South Carolina, adding new domestic primary aluminum capacity at a time when US trade policy is reshaping metal supply economics. The company expects the expansion to reach full production by the end of June 2026.

The expanded Century Aluminum Mt Holly smelter is expected to reach nameplate capacity of 229,000 t/yr. Century said the additional output will increase total US primary aluminum production by 10%.

Century Aluminum Mt Holly smelter output matters because the US has been trying to rebuild domestic primary aluminum supply after years of capacity pressure. Higher tariffs, energy costs and import dependence have made aluminum smelting a strategic industrial issue.

Section 232 Tariff Supports Domestic Aluminum Expansion

Century’s expansion follows the implementation of the 50% Section 232 aluminum tariff in June 2025. The tariff has improved the incentive structure for domestic primary aluminum production by raising the cost of imported material.

Primary aluminum smelting is highly energy-intensive, so producers need a combination of power competitiveness, policy support and long-term demand visibility. The Mt Holly expansion shows that tariff protection can influence production decisions when capacity is already available for restart or expansion.

The added output will not remove US import dependence. However, a 10% increase in domestic primary aluminum production is meaningful in a market where every operating smelter carries strategic value.

Domestic aluminum is important for packaging, transportation, construction, defense, electrical infrastructure and manufacturing. Greater local supply can reduce exposure to import volatility and support downstream users seeking more secure metal availability.

Century Extends US Aluminum Strategy With Oklahoma Project

Century is also pursuing a larger domestic growth strategy beyond Mt Holly. The company has teamed up with Emirates Global Aluminum to build a planned 750,000 t/yr primary aluminum smelter in Oklahoma.

That project would represent a much larger change to US aluminum supply if completed. It would add major greenfield smelting capacity and strengthen the country’s ability to supply downstream manufacturing from domestic primary metal.

The two projects show how US aluminum policy is moving from import management toward capacity rebuilding. Mt Holly provides a near-term production increase, while Oklahoma represents a longer-term industrial supply-chain bet.

For the US market, the key question is whether tariff protection, energy availability and industrial demand can support sustained investment in smelting. Without competitive power and stable policy, primary aluminum capacity remains difficult to maintain.

The Metalnomist Commentary

Century’s Mt Holly expansion shows that tariff policy is beginning to translate into real domestic aluminum output. The bigger test will be whether the US can turn short-term protection into long-term smelting competitiveness through power access, investment and downstream demand.