A Decision-Support Approach to the Sustainable Management of Extractive Waste: Application of the DST-SRM Tool to the Montorfano Case Study

In line with the EU Green Deal and strategic policies on critical raw materials (CRMs), the sustainable management of extractive waste is a major challenge for Europe. To address this, the Decision Support Tool for Sustainable Resource Management (DST-SRM) has been developed as a digital platform enabling the assessment of alternative scenarios for extractive waste (EW) valorisation.

The DST-SRM tool integrates geological, environmental, and economic datasets and applies Multicriteria Decision Analysis (MCDA) to identify potential resources by assessing significant quantities of unexploited minerals and associated by-products. It enables the development of multiple scenarios, the selection of traditional and/or advanced processing techniques for each scenario, and the comparison of scenario outcomes to identify the most sustainable solution. Each scenario is defined through a flowchart that specifies, for each activity, the machinery and equipment used with the relevant technical specifications, the quantities of material processed, and the resulting products or waste. Based on these data and site-specific information, the environmental, economic, and social impacts are assessed using quantitative and semi-quantitative approaches for each scenario.

The Montorfano granite quarry, located in northern Italy, was selected as a case study for DST-SRM validation. This quarry has large deposits of mining waste (covering 200,000 m²), now authorised as a mining site for the exploitation of RM to feed a dedicated treatment plant (approximately 140,000 t/year). Site-specific data included geological and hydrogeological data, chemical and mineralogical composition (55% feldspar, 40% silica, 5% mica), and waste size distribution. Site-specific data also includes characterisation of the area surrounding the extraction site (populated areas, transport routes, distances to facilities, etc.).

Nine scenarios were simulated, ranging from in situ remediation (capping) to advanced secondary recovery techniques, including magnetic separation and dust treatment. The results indicate that the most sustainable option corresponds to the company’s current operating practice, represented by the final scenario evaluated, which achieves the best balance among environmental, economic, and social performance.

Continuous process improvement, together with the recovery and commercialisation of all end products and strategic market diversification, enables the company to maximise economic returns while reducing environmental and social impacts. In this context, the implementation of effective dust extraction systems not only enhances workers’ health and safety but also allows the recovered dust to be valorised as a marketable product.

The Montorfano case study confirms the DST-SRM’s ability to support inclusive, evidence-based decision-making and represents a starting point for operators and stakeholders, promoting extractive waste valorisation within a circular economy by transforming environmental liabilities into strategic secondary resources.

Keywords: Decision Support Tool, Critical Raw Materials, Extractive Waste, Circular Economy, Sustainable mining