White steel slag from ladle furnace as calcium carbonate replacement for nitrile butadiene rubber: A possible industrial symbiosis

Over the years, natural resources conservation and waste management have become increasingly important globally, leading to the promotion of systemic approaches that integrate different processes by sharing materials, energy, and services. Recycling and reuse of materials have also become an area of increasing interest. This study investigates the potential use of ladle furnace (LF) slag, a waste product of the steel industry, as a non-conventional filler for rubber compounds. LF slag is produced during the refinement stage of the steelmaking process and is almost entirely landfilled. This research compares a standard nitrile-butadiene rubber (NBR) filled with calcium carbonate to an NBR filled with 10% LF slag (by volume). The study evaluates the compounds' processability and mechanical performance by means of rheometer analysis, hardness test, tensile test, compression test, and compression set. The use of LF slag in NBR rubber compounds could represent an example of a circular economy, where waste from one industry becomes a raw material for another.