Sustainable solutions for using seawater in the copper mining industry

Abstract

The copper mining industry plays a key role in the shift towards renewable energies, and relies primarily on the extraction of copper sulfide ores. However, many copper mining companies use seawater or desalinated water in their operations due to their presence in dry or semi-arid regions. In mineral processing operations, the utilization of seawater as the process water has detrimental effects on both the froth flotation and dewatering processes. In addition, ore processing operations generate a significant volume of mine tailings, almost equivalent to the amount of ore treated, and inadequate management of these tailings poses a considerable environmental challenge due to the generation of mine drainage. Based on these antecedents, this dissertation focuses on proposing water management strategies from a technological and environmental perspective to achieve sustainable development in the copper mining industry located in water stress regions. In this context, the objectives of this dissertation are 1) to evaluate the performance of the mineral processing operation incorporating partial seawater desalination technology and 2) to analyze the environmental impacts of the mineral processing operation applying novel uses of seawater or desalination waste brine. This methodology is based on an experimental approach, where laboratory experiments were developed and evaluated from a technical and/or environmental perspective to demonstrate the feasibility of the proposal. The main findings indicate that the use of partial seawater desalination technology offers an alternative for processing porphyry copper ores. This technology effectively reduces the concentration of divalent ions (calcium and magnesium), which can negatively affect the efficiency of froth flotation and dewatering processes, especially when copper sulfide ores contain a significant amount of clay. In addition, partial desalination technology provides an alternative approach to address the disposal of waste brine from reverse osmosis desalination facilities, creating an opportunity for its beneficial use that can bring about economic advantages while mitigating the environmental consequences associated with its discharge into the ocean. Another noteworthy result is that the use of seawater helps to prevent the generation of acid mine drainage in tailing storage in dry areas. The main contribution of this dissertation is in demonstrating that partial seawater desalination technology can help to minimize freshwater withdrawal in the copper mining industry located water stress region, maximize water efficiency and reuse it from the tailing dewatering process, and increase copper recovery in the froth flotation process, aiming to support the increase in copper production to facilitate the global energy transition.