Tailings management in iron ore mining rose to prominence following the dam failures in 2015 and 2019 in Brazil, underscoring the urgent need for safer and more sustainable practices. In response to these events, the Global Industry Standard on Tailings Management (GISTM) was introduced to guide the adoption of best practices aimed at ensuring the safety and integrity of tailings disposal structures. Dry stacking has emerged as a viable alternative to conventional tailings dams, as it minimizes water retention within the tailings, thereby reducing hydraulic risks.

This paper presents a detailed protocol for the chemical, mineralogical, and hydrogeochemical modeling—both conceptual and numerical—of iron ore beneficiation waste. The protocol was developed for one of the first dry stacking facilities in Brazil, implemented in response to the 2015 dam failure. The proposed methodology enables continuous assessment of the chemical stability of the waste, integrating hydrochemical analyses and monitoring the reagents used in the beneficiation process. The developed hydrogeochemical model follows a systematic and integrated approach, utilizing the available information about the structure. Its objective is to consolidate data on the factors influencing fluid percolation and movement, considering geotechnical, hydrogeological, and hydrochemical aspects, as well as the physicochemical and mineralogical properties of the materials involved.

Three key conditions were identified within the context of the structure. The first relates to seasonal fluctuations in the water level within the structure, which control the geochemical conditions. Second, the numerical model investigated the degradation of ether-amines—reagents used in the beneficiation process—and how their breakdown may affect the redox environment within the structure. Lastly, an analysis was conducted to evaluate the potential for chemical clogging of the bottom drains of the dry stack.

Successfully conceived and implemented, the protocol has proven to be a valuable tool for the continuous assessment of the chemical stability of these materials. It offers an integrated methodology encompassing the hydrochemical analysis of effluents and industrial waters, as well as the monitoring of organic reagents used in mineral processing. The results indicate that primary iron ore beneficiation practices comply with international standards and best industry practices, reinforcing the commitment to safety and sustainability in mining operations.

The mining activities of Lorraine coalfield (France) caused drawdown of the Lower Triassic sandstone aquifer. This was due to extensive mine drainage and additional water extraction by surrounding industries and communities. The prolonged water table decline over a century led to the drying of wetlands, while regional land development proceeded without recognizing the unsustainable nature of this water depletion. With the cessation of coal mining in the early 2000s and the gradual closure of other water-intensive industries from the 1980s onward, the Lower Triassic sandstone aquifer began to recover. In this paper, the authors provide a detailed description of the coalfield's general conditions, the methodology used for long-term flood risk management in vulnerable built-up areas.

In response to these challenges, GEODERIS and BRGM implemented a 3D hydrodynamic model to assess and predict the long-term influence of groundwater recovery. After a history matching phase based on available geological and piezometric data, predictive simulations were conducted to first estimate future water table levels and then guide the gradual deployment of the pumping network in flood-prone zones. Two climate simulations based on the work of the IPCC were utilized: one representing average rainfall and the other representing intense rainfall. These scenarios were used to estimate the effect of climate change on the extent of vulnerable areas and to inform adaptations for the well field.

Initial findings revealed that the groundwater rebound occurred at varying rates on either side of the Longeville-Hombourg fault, faster in the western part of the basin. Moreover, numerous built-up areas in the western sector are already at risk from the rising water table, with projections extending to the eastern sector by the 2040s–2050s. The predictive simulations were also used to calculate the pumping flows required to manage this risk.

To mitigate the potential influence of rising groundwater, a network of pumping wells is to be implemented to maintain water table levels at a minimum depth of 3 meters in vulnerable areas. In addition, a comprehensive piezometric monitoring network is to be set up to track water table dynamics across the different geological compartments, enabling model refinement and adaptive management of the well field. Given the assumptions underlying the 3D numerical model and the time scale of the concerning phenomenon, the overall strategy adopted is clearly data-driven. This approach aims to improve forecasts and refine geological and hydrogeological interpretations of the coalfield.

Mines and mining companies face two main challenges to translate broad corporate water stewardship goals to meaningful site level investment plans to manage their water projects and to intern link these site level actions to wider water resource goals. Firstly, the level of investment needed to bring mining projects to the desired level of maturity, depending on corporate commitments is challenging given the cost pressures of commodity pricing, the requirements of the project and other priorities competing for investment. Secondly, mining companies are challenged to present their position to their stakeholders in a transparent manner that justifies investment decisions and presents a realistic picture of where they are in terms of what is achievable.

Benchmarking can be considered to address these two challenges as a useful tool to both understand what is achievable versus level of investment and to build trust with stakeholders on the current state of maturity of the company or project portfolio. However, quantitative benchmarking of mine water use within the mining industry has been difficult to achieve given the integrated nature of mines with their environments as opposed to other industry where systems are less integrated. Also, the number of factors affecting mine water benchmarking is substantial, and it is therefore not meaningful to compare all mines with one another. With this in mind, we have developed an innovative methodology to undertake meaningful quantitative benchmarking making use of publicly available information and industry understanding which compares mines of technical similarity in terms of mine water metrics.

This paper will focus on the use of this benchmarking data, the factors to consider in the interpretation of publicly available water data, along with the limitations of such a benchmarking exercise. Relevant examples will be discussed to demonstrate the value of and potential use of the benchmarking outcomes.

This tested quantitative benchmarking methodology has been developed to allow mining companies to use benchmarking in a way that is meaningful to their planning and investment processes, reporting, and stakeholder engagement. It can be used to guide executives in setting company commitments as well as to provide the basis for project level investment decisions to execute projects aligned with those commitments. And finally, it can be used to support building trust with project stakeholders and communities when reporting on progress and making future commitments, satisfying ESG commitments and avoiding claims of greenwashing.