Loading...
Sustainable reuse of mine tailings through production of geopolymer construction materials
Clements, Cara Leigh-Fragomeni
Clements, Cara Leigh-Fragomeni
Citations
Altmetric:
Advisor
Editor
Date
Date Issued
2024
Date Submitted
Collections
Research Projects
Organizational Units
Journal Issue
Embargo Expires
Abstract
As society progresses and especially as the transition is made from fossil fuel to clean energy, the demand for minerals and precious metals is expected to double over the next 20 years. While extractive mining is critical for technological progress, mining activities produce a large volume of a hazardous waste stream, known as mine tailings. This waste is stored onsite indefinitely, and current management strategies fall short in terms of safety, environmental protection, and longevity. Valorization of mine tailings to produce valuable materials is a growing area of research and offers a solution for management of large volumes of mine tailings. Geopolymerization is a technology that can not only sequester and stabilize the toxins in the tailings, but also produce construction materials such as bricks, concrete, and pavers.
Mine tailings-based geopolymers have shown high compressive strength but often have durability problems such as low stability during water immersion and poor freeze-thaw performance. The overall research goal was to develop suitable techniques for producing strong and durable geopolymers from MTs source material. The specific objectives included identifying suitable sources of MTs, recommending alternative procedures and source materials for application in Peru, developing strategies to improve hydrolytic stability, formulating a mix design with sufficient freeze-thaw performance, and evaluating ASTM brick standards for application in geopolymer systems. These objectives were achieved through systematic laboratory experiments that connect the microstructure of geopolymer bricks to the resulting compressive strength, engineering performance, and durability during water immersion and freeze-thaw cycles.
This thesis presents a variety of strategies that can dramatically increase the compressive strength, improve the hydrolytic stability, and provide satisfactory freeze-thaw protection for MT-based geopolymer bricks. Using co-alkali activation with sodium hydroxide and sodium silicate improved the strength retention of bricks during a seven-day water immersion test from 30% to 47%. Application of a high-temperature treatment after the normal curing/drying process increased the compressive strength to 20-30 MPa and 100% MT-based bricks remained intact after 25 cycles of freeze-thaw. Addition of fly ash or slag as a supplementary aluminosilicate source can produce bricks with compressive strength greater than 40 MPa, and bricks retained 85-95% of their original compressive strength after 50 cycles of freezing and thawing.
This thesis contributes to the knowledge base of the microstructure and durability of MT-based geopolymers and also provides practical solutions to their most pressing performance problems. By applying the strategies presented here, MT-based geopolymer bricks can be produced that meet all the requirements set forth in ASTM C62 standard for masonry bricks. The conclusions of this research project allowed us to achieve Technology Readiness Level 4 (system validation in a laboratory environment) and paved the way for large-scale production of geopolymer bricks in Arequipa, Peru.
Associated Publications
Rights
Copyright of the original work is retained by the author.