Chile Approves Use of Copper Slag as Artificial Aggregate

Why It Matters

The approval creates a new, sustainable market for mining waste, cutting aggregate extraction and reinforcing circular‑economy practices in the mining sector.

Key Takeaways

• Copper slag now legally usable as construction aggregate in Chile.
• Sanitary approval required; limited to specified infrastructure applications.
• Pilots proved slag can safely replace natural aggregates in roads.
• Anglo American and Codelco led research, enabling regulatory approval.
• Circular economy gains reduce environmental impact and aggregate demand.

Pulse Analysis

Chile’s copper industry generates millions of tonnes of slag each year, a by‑product traditionally stockpiled or disposed of in landfills. Composed mainly of iron oxides and silica, the material poses environmental challenges if left untreated, especially in water‑sensitive basins. Until now, regulatory barriers limited its reuse, despite its physical properties that closely match those of conventional aggregates. The new decree reframes slag from a liability into a resource, aligning with global trends toward waste valorisation and stricter sustainability standards.

The regulatory breakthrough stems from a coordinated effort between the Ministry of Health, Mining, Public Works and Environment ministries, and mining giants such as Anglo American and Codelco. After extensive pilot projects—like the Loncura road and the Chagres Smelter paving—authorities confirmed that, with proper sanitary controls and leaching tests, slag can meet construction safety criteria. The decree mandates regional health secretariats to grant use permits, ensuring traceability and environmental monitoring. This collaborative model showcases how industry‑led research, university partnerships, and government oversight can translate technical feasibility into legal certainty.

For the mining sector, the policy unlocks a valuable revenue stream and reduces the need for virgin aggregate extraction, a critical advantage in water‑scarce regions like the Aconcagua basin. Companies can now market slag‑based products domestically and potentially export them to neighboring markets facing aggregate shortages. While the framework sets high compliance standards, it also incentivises further innovation in slag processing, such as chemical stabilisation and composite material development. Overall, Chile’s move positions it as a regional leader in circular mining, offering a replicable blueprint for other resource‑rich economies seeking to turn waste into wealth.