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Making Paving Stones from Copper Mine Tailings as Aggregates
Elizabeth J Lam1, Vicente Zetola2, Yendery Ramírez1,3
1Chemical Engineering Department, Universidad Católica del Norte, Antofagasta CP 1270709, Chile.
Summary
This study demonstrates that incorporating copper tailings into cement mixtures significantly enhances mechanical properties, enabling their use in paving stones for tailings dams. This approach offers a sustainable solution for managing mining waste.
Area of Science:
- Materials Science
- Civil Engineering
- Environmental Engineering
Background:
- Copper mining in Chile generates substantial tailings, posing environmental risks.
- Utilizing these tailings in construction materials can mitigate environmental hazards and promote sustainable practices.
- Existing Chilean standards for concrete aggregates necessitate specific fines content limitations.
Purpose of the Study:
- To evaluate the mechanical properties of Portland cement mixtures incorporating copper tailings as aggregates.
- To determine the feasibility of using these mixtures for manufacturing paving stones for inactive tailings dams.
- To assess the impact of tailings fines content and superplasticizer additives on mixture performance.
Main Methods:
- Characterization of tailings from two Chilean dams (inactive and active) including granulometry, pH, humidity, Eh, and mineralogy.
- Preparation of cement mixtures with tailings and conventional aggregates, controlling fines content below 0.075 mm.
- Mechanical testing (bending and compression strength) of cured specimens according to Chilean standards.
Main Results:
- Tailings from Dam 1 had 76.2% fines (N°200 ASTM sieve), exceeding limits for direct use as aggregate.
- Mixtures with partial tailings addition (7% fines < 0.075 mm) showed a 26% increase in bending strength and 180% in compression strength.
- Superplasticizer additives improved the workability of mixtures containing tailings.
Conclusions:
- Incorporating a portion of copper tailings into cement mixtures significantly improves mechanical strength.
- The developed mixtures are suitable for manufacturing paving stones, offering a viable use for mining waste.
- This research provides a sustainable pathway for repurposing copper tailings in civil engineering applications.
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