Potential Application Of Recycling Coal Combustion By-Products-Based Zeolites To Clean-Up Acid Mine Drainage – A Case Study From Marmato, Caldas, Colombia
Ríos Reyes, Carlos Alberto (1); Valente, Teresa (2)
1: School of Geology, Universidad Industrial de Santander, Colombia; 2: University of Minho, Portugal
Acid mine drainage (AMD) resulting from the microbial oxidation of pyrite in presence of water and air, affording an acidic solution that contains toxic metal ions, is a widespread environmental problem associated with both working and abandoned mining operations. AMD is a focus of environmental impact with important expression on the water systems. Nevertheless, it often is responsible for the complete degradation of ecosystems due to mobilization of potentially toxic elements (PTE). Therefore, minimization of its effects became a major concern for mining industry. In this way, development of measures for treatment or minimization of the contaminated effluents is an increasingly critical issue of research.
New ways for recycling coal combustion by-products should be quickly developed due to the shortage of landfill sites and stricter environmental regulation, which can be done through its use in zeolite science. Zeolites are well-known crystalline microporous materials with a three-dimensional structure. Due to their exceptional properties, zeolites have been widely used in numerous technical applications as catalysts, adsorbents and ion exchangers. At present, synthetic zeolites are used commercially more often than natural zeolites due to the purity of crystalline products and the uniformity of particle sizes. Zeolites are usually synthesized from pure chemicals. However, the preparation of synthetic zeolites from silica and alumina chemical reagents is expensive. Such costs may be reduced by the use of several industrial wastes like coal by-products as starting materials.
Based on preliminary results, recycling coal combustion by-products-based zeolites have the potential to effectively remove heavy metals from AMD generated by mining activity developed at both Marmato, Caldas (Colombia) and worldwide scale. Therefore, these versatile materials can be applied in waste management scenarios and suggested as an alternative material for AMD remediation. The aim of this study is investigating the use of coal combustion by-products as low-cost materials in the synthesis of zeolites with potential application to clean-up AMD.
The present work is focused on the tertiary level of AMD control, which consists on the development of measures for its correction. The proposed approach fits into the concept of circular economy since it considers the use of recycled materials for such a purpose.