Direct ink writing of recycled magnesite refractories from ladle metallurgy waste

Refractory linings in ladle metallurgy are heat-resistant materials that protect ladles from high temperatures and aggressive chemicals during metal processing. They must withstand mechanical wear, chemical corrosion, and thermal shocks. The most common lining materials are MgO and CaO bricks, known for their high temperature resistance and good durability against both acidic and basic slags. This process generates significant amounts of waste due to wear and spalling during operation. While some by-products are already being reused, a large portion is still landfilled. This study focuses on the development of a new type of refractory material produced using direct ink writing. For this purpose, MgO refractory waste (MGW) was mixed with either B1M or IBV kaolins. A total of 12 mixtures with the addition of 50, 60, 70, 80, and 90 wt% MGW were prepared. All materials were characterized using chemical, phase, granulometric, and scanning electron microscopy analyses. Rheological properties of the mixtures were studied. For each sample, two firing temperatures (1000 °C and 1200 °C) were tested. Compressive strength, bulk density, apparent porosity, and water absorption of the fired samples were evaluated.