Mine waste as a sustainable resource for facing bricks

Abstract

Circularity of raw materials starts with a zero-waste approach to any (potential) resource. The increasing pressure on the primary raw materials sector and external market dependence can ultimately lead to scarcity of natural resources. To minimise this pressure, alternative materials need to be mapped, characterised, and valorised. Construction and demolition waste and mining waste are currently the biggest waste streams in the EU27 and can lead to environmental, health, and social hazards. The purpose of this study is to evaluate the sustainable use of (clean) sulphidic mining waste materials in facing bricks.After materials’ characterisation, a company-specific blend for facing bricks has been modified on a lab scale, by partly replacing primary raw materials with mining waste materials (Plombières tailings and Neves Corvo waste rocks). The production processes, product quality, and environmental performance of waste-derived bricks were assessed and compared to standards and regulatory limits. A cradle-to-gate life cycle assessment (LCA) was performed to evaluate the environmental profiles of the best performing waste-derived bricks compared with standard bricks.Results show the suitability of using the untreated Plombières tailings material in facing brick blends, giving satisfactory technical and aesthetical properties, and complying with environmental regulations for service, 2nd life, and end-of-life stages. According to the LCA, facing bricks made with 40 wt% Plombières tailings demonstrated better environmental performances than standard bricks. The pre-treated Neves Corvo waste rock materials were unsuitable for facing bricks due to the high sulphur and metal(loid)s content that caused aesthetical and chemical-environmental problems.