Life cycle assessment of refractory waste management in a Spanish steel works

A life cycle assessment (LCA) is conducted on the current refractory waste management practices in a steel works in Spain producing around 6,000 tonnes of refractory waste in 2018. Management practices included direct reuse of spent magnesia-carbon (MgO-C) bricks, recycling of MgO-C bricks and high-alumina refractories by an external contractor and landfilling of monolithics and isostatic refractories, for which there were yet no established valorization routes. This current situation was compared to a hypothetical scenario where all refractories were disposed in landfill. The LCA included waste management activities (collection, transport, treatment) as well as production of substituted primary materials (dead-burned magnesia, calcined bauxite and new MgO-C bricks) produced in China and Germany. Results are discussed for four indicators: greenhouse-gas emissions, Non-renewable energy demand, land use and water use. Overall, per tonne of produced waste, the current management leads to a reduction or saving of 0.54 tonnes CO₂-eq, 3 GJ primary energy from non-renewable sources, the occupation of 10 m² of land during one year and the abstraction of 5 m³ freshwater. The results also show that reuse, in the particular case of spent MgO-C bricks, leads to higher benefits than recycling by At least a factor four. The robustness of these results is confirmed through the application of a Monte Carlo uncertainty analysis, as well as a sensitivity analysis focusing on a shift from coal to natural gas in the Chinese refractory industry.