Sustainability Assessment of Celestine Production and Tailings Enrichment with Flexible Circuits

Journal article, 2025

Strontium is classified as a critical raw material by the European Commission and is mainly found in celestine ore. Within Europe, largest reserve of celestine is found at a mine in Spain. The mine utilizes diesel-powered mobile machines in the processing circuit, which enable changes in the processing circuit, providing flexibility to handle varying grades of Run-of-Mine ore and produce multiple-size fractions of celestine. However, this flexibility leads to material and energy consumption variations, increasing the complexity of assessing the environmental impacts of celestine. This study investigates the environmental impacts of producing multiple grades and size fractions of celestine in a flexible processing circuit setup, along with economic implications. Using Life Cycle Assessment (LCA), an automatic allocation tool, and site-specific data, the relationship between circuits and the environmental impacts of celestine was investigated. Multiple scenarios were assessed, comprising a mobile crushing plant and additional tailings enrichment in the circuit. Cradle-to-gate LCA results show that, circuit comprising a mobile crushing plant producing multiple-size fractions of celestine had a Global Warming Potential (GWP)-total impact of 1.29 kgCO2-eq./tonne, which is 3% lower than the circuit producing a single size-fraction (1.33 kgCO2-eq./tonne). Circuit with tailing enrichment demonstrated an increased revenue of at least 14% but raised GWP-total by 63%, reaching 2.18 kgCO2-eq./tonne, compared to 1.33 kgCO2-eq./tonne for circuit without enrichment. The increase in GWP-total was mostly attributed to increased consumption of ferrosilicon and diesel during the enrichment process. However, these results are specific to the system boundary assessed in the study. Using revenue calculation and LCA for circuit evaluation helps in comparing economic and environmental aspects of the circuits.