Comparative Preliminary Life Cycle Assessment (LCA) of Calcined Bauxite- and Taconite Tailings-based High Friction Surface Treatments (HFST)

Abstract

The University of Minnesota Duluth Natural Resources Research Institute (NRRI) completed a preliminary, screening cradle-to-gate life cycle assessment (LCA) of high friction surface treatments (HFST) manufactured from calcined bauxite and taconite tailings. The potential environmental impacts of the HFSTs were then compared.

The system boundary included material and fuel consumption for calcined bauxite and epoxy resin, material and fuel consumption for size reduction of calcined bauxite and taconite tailings, as well as transport of materials to the HFST application site. Because this preliminary screening LCA study was cradle-to-gate, use-phase activities and disposal/recycling of the HFSTs at end-of-life were excluded. The majority of the life cycle inventory (LCI) data was secondary data from the DATASMART LCI database. This study also used the cut-off approach method for recycling and utilized the LTS 2019 v1.02 method to translate the LCI data into environmental impacts; this method combines the ReCiPe Endpoint (H) v1.05 method with three endpoint categories (Human Health, Ecosystems, Resources) and the Cumulative Energy Demand, Climate Change, and Water Use impact categories.

A contribution analysis of the taconite tailings-based HFST showed that the use of epoxy resin for binding the taconite tailings aggregate accounted for nearly 95% of total impacts in each impact category, while mixing the epoxy resin and aggregate accounted for between 1.36% to 4.21% of the total impacts in each category. A comparative analysis showed that the taconite tailings-based HFST had between 55% and 31% fewer impacts than the calcined bauxite-based HFST across all impact categories. In addition, transportation of the calcined bauxite from China is a large contributor to the overall environment load of the calcined bauxite-based HFST.