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Life Cycle Assessment (LCA) is a widely-used methodology for estimating the potential environmental impacts of technological systems in nature. Relative maturity of this method has been achieved thanks to recent standardization efforts, although there are still several challenges, particularly in the minerals industry where LCA still needs to be strengthened and extended in use. An exhaustive review of recent LCA studies on mining and mineral processing operations was conducted to identify how these have dealt with various methodological challenges. A total of twenty-nine studies were found, most of which focusing on developed regions and in three commodities: coal (28%), aggregates (21%), and copper ores (14%). The source of data for background processes has been the Ecoinvent database in 45% of the studies analyzed, whereas the SimaPro software has been the preferred LCA tool in 66% of such studies. Although important advances have been made, significant issues remain. For instance, inconsistencies were found in the definition of the functional unit and system boundaries (temporal and technological). Further, the adoption of allocation criteria and the use of normalization and weighting in impact assessment have not been considered in most cases. While climate change was the main environmental hotspot (more than 90% of the studies addressed this impact category), the impacts associated with water use and waste management have been overlooked in most studies. Furthermore, mining and processing operations have been described as generic, averaged values or as simple functional relationships between system inputs and outputs using parameters without physical significance ("black box models") in several production chains, making it difficult to identify opportunities for environmental sustainability enhancement within the sector. The work then discusses the opportunity of improvement in LCA in the minerals industry through the incorporation of process simulation from a bottom-up perspective. Evidence from other industries and recent advances in the computational development of such tools for the mineral sector are reviewed, which suggests that there is an opportunity for reducing the epistemic uncertainty in future LCA studies of mining and processing operations through the combination of both approaches. Image 1 • Critical evaluation of recent peer-reviewed LCA studies in the minerals industry. • Methodological challenges of LCA within this sector are discussed. • Potential improvements in LCA from a bottom-up approach are examined. • Process simulation coupled with LCA can become a reality for the mining sector. [ABSTRACT FROM AUTHOR]

A considerable portion of energy consumption and, as a consequence, operational costs in mineral processing, is associated with comminution. High Pressure Grinding Rolls (HPGR) are appealing for their energy efficiency and resulting lower operating costs. This article evaluates this technology as an alternative to the conventional fused alumina comminution route of a specific plant comprising a complex roll crushing circuit. Two fused alumina samples, called BT and TB, were submitted to HPGR (open circuit) and physical characterization (DWT, BBWI, bulk density, specific gravity) tests. In addition, simulations were conducted using JKSimMet® 6.0 software, aiming to predict the performance of a closed circuit equipment and scale-up of an industrialscale unit. Product size distributions of the open circuit HPGR tests and closed circuit HPGR simulations were compared with the product size distribution required by the industrial comminution circuit. The required throughput was also evaluated. Results show that the alternative HPGR route provides a remarkable potential for circuit simplification, while considerably reducing the number of comminution equipments from 13 to 1, which facilitates operational control and possibly reduces operating costs. [ABSTRACT FROM AUTHOR]

• Innovation is key to improving the environmental performance of the mining industry. • Benefits of adopting circularity (open-loop CDW recycling) in mining are exhibited. • Novel LCA scenarios in aggregates production combining state-of-the-art methods. • Mine-to-product simulation assists in reducing epistemic uncertainty in LCA. • Comprehensive and regionalized LCI considering both mine and product life cycles. Sustainability in mining must be envisioned from a more comprehensive perspective that involves the management of primary and secondary resources and that prioritizes the adoption of innovation beyond a techno-economic mindset. The holistic Life Cycle Assessment (LCA) methodology is useful to diagnose the environmental profile of mining operations seeking a greater contribution to sustainability. This work proposes an enhanced life cycle-based approach for the minerals industry, which is supported by mine-to-product process simulation, scenario analysis, and a comprehensive and context-specific data collection involving the life cycles of the product and the mining project. The convenience of this approach in terms of reducing epistemic uncertainty is demonstrated with a Brazilian case study of a large-scale granitic quarry operation. It is shown that mining can contribute to sustainability by adopting sustainability-driven innovation and circularity principles. The proposed methodology can be applied to other mineral commodities and geographic contexts. [ABSTRACT FROM AUTHOR]

Comminution is an essential step in processing itabirite ores, given the need to liberate silica and other contaminants from the iron minerals for downstream concentration and then pellet feed production. In general, these ores in Brazil are not particularly hard to crush and grind, but both capital (CAPEx) and operating (OPEx) expenditures in this stage of preparation can be critical for the project, in particular due to uncertainties in iron ore prices. Several circuits have been designed and are in operation for this type of ore in Brazil; however, it is not yet clear which technologies are more cost-effective and in which configuration they should be applied. This work critically analyzes four comminution circuits for an undisclosed case study. For these circuits, CAPEx, OPEx, and some environmental sustainability indices, as well as qualitative technical criteria, were used in the comparisons. This work concludes that two of these process routes, especially those based on more energy-efficient technologies (and one of these still rarely explored even at bench-scale), have demonstrated to be very attractive from multiple standpoints. [ABSTRACT FROM AUTHOR]

A switch on-switch off (SOSO) approach to mining relies on an integrated modular and mobile plant. It is appropriate for rapid start-up and cessation of production from ore deposits that have economic viability dependent on fluctuating commodity prices. This study aims at assessing the environmental performance of the SOSO approach in a life cycle perspective, using evidence collected during its pilot-scale implementation on a high-grade lead deposit located in Bosnia-Herzegovina. The deployed modules include: i) a selective mining tool, ii) a comminution module with crusher and screen, and iii) a gravity separation module with screen, spirals and a shaking table. The Life Cycle Inventory is based on a comprehensive and transparent set of data, drawn from the on-site pilot tests, completed with additional calculations (including process simulation with USIM-PAC®), scenarios (regarding energy), and some generic data and assumptions. The potential environmental impacts are calculated considering 13 impact categories of the EF 2.0 impact assessment method. The production of one tonne of Pb concentrate, with a Pb-content of 58.7%, induces in particular the potential generation of 897 kg CO 2 -eq. Moreover, the contribution analysis enables identification of the environmental hotspots, including the consumption of electricity supplied by on-site diesel generators that contributes to more than 90% of the total impacts in seven impact categories. Finally, this article discusses i) how advantageous the SOSO approach is compared to large-scale lead mining regarding some of its associated key environmental hotspots, ii) the potential for reduction of the impacts associated with electricity consumption, in particular through the implementation of a renewable electricity supply mix (solar photovoltaics and biomass-based), iii) the contributions of equipment and tailings to the total impacts, and iv) the contribution of the SOSO approach to resource accessibility and depletion. The inclusion of data outputs of mineral processing simulation in LCA appears a promising development towards optimization of the SOSO modular process chain, based on life-cycle environmental criteria and accounting for the site-dependent variability of ores and processes. • The environmental performance of switch on-switch off (SOSO) mining is assessed. • Contributions of extraction activities to key impacts reveals space for improvement. • SOSO approach increases the potential to make use of the value of metals in ground. • Advantages of SOSO approach are increased by suitable electricity demand and supply. • Toxicity and ecotoxicity impacts are influenced by equipment and tailings management. [ABSTRACT FROM AUTHOR]