Analysis of the mechanical properties of agglomerates produced under alternating conditions for the reuse of by-products from metallurgical processes

By-products such as slag, sludge and fine dust from various iron and steel industries and foundries have high value due to their potential to recover iron and iron oxides as metallic iron, which can reduce the amount of waste sent to landfills and environmental pollution. In this study, different fine dusts and sludge were processed into agglomerates using a suitable reductant and formed via stamp pressing under varying contents and conditions. Instead of cement-based binders, biogenic alternatives such as potato starch, wheat starch and molasses oil were employed, and their influence on the mechanical properties of the agglomerates was examined, with the main emphasis on the cold compressive strength. Additionally, various amounts of fibrous materials were added to improve mechanical performance.

To optimize the mechanical properties, multiple recipes were systematically tested under different compaction pressures, binder compositions and curing conditions. The influence of fibre content and pressing parameters as well as curing time and temperature was evaluated to identify optimal combinations. The results show that biogenic binders, especially starch-based ones, in combination with fibre additives and an optimised curing, significantly enhanced the cold compressive strength of the agglomerates. The findings contribute to the development of sustainable, high-performance agglomerates suitable for industrial reuse and lay the foundation for further upscaling and application in metallurgical processes.