Estudo de impactos ambientais do processamento mineral de cobre no Brasil por meio da avaliação do ciclo de vida

Abstract

The energy transition from fossil energy sources to cleaner ones is an important process for reducing greenhouse gas emissions and the effects of climate change. However, new technologies will lead to a large increase in the demand for certain minerals, evidencing other associated environmental risks in the mining sector. Therefore, it is fundamental that the main impacts are assessed and that potential alternatives to reduce such adverse environmental impacts, discussed in literature on sustainability in critical minerals production are analysed. The objective of this study was to apply the Life Cycle Assessment (LCA) methodology to a copper operation in Brazil and to identify the most relevant impacts, as well as to search for routes to a more sustainable production. There are few studies on assessments of mining operations with a focus on South America and Brazil, what justifies the importance of this work. For the development of this work, case studies of LCA application for critical minerals for the energy transition were reviewed, with the aim of analysing the main methodological choices; then, the methodology was applied to a copper mining and concentration unit in the northeast region of Brazil, combining data from the literature with data from the operation. The LCA was performed in the OpenLCA software, using the inventory evaluation of the ReCiPe methodology in two different approaches: black box process and product system. Then, a sensitivity analysis was carried out for the main parameters of the system and, based on the results obtained and the literature review, scenarios for improving eco-efficiency in the production process of copper concentration were proposed. The results obtained show that the impacts of copper production are mainly related to toxicity aspects, the categories of Terrestrial Ecotoxicity and Human Toxicity: Non-Carcinogenic were found to be the most relevant. The two approaches in the modelling generated different results, but both indicate the same categories as more relevant. Regarding the contribution of flows and processes, consumption of electricity, handling of waste rock and treatment of tailings are the most relevant, but consumables form the concentration process also have considerable impacts in the categories of ecotoxicity, human toxicity and Terrestrial Acidification. The results are consistent with the impacts observed by previous works in other copper operations in the world, with great sensitivity of the results to electricity consumption and ore grade. The recent development of technologies for mineral processing has potential applications in copper operations, to reduce environmental impact through more energy-efficient systems, best asset management practices, green reagents and innovative tailings treatment technologies. However, industrial-level evaluations and economic assessments are necessary to prove the potential use of these technologies on an industrial scale.