In Situ Observation of the Carbothermic Reduction and Foaming of Slags in Silicomanganese Production

The carbothermic reduction of slag in silicomanganese production is accompanied by the release of carbon monoxide. This gas can accumulate as bubbles within the slag, leading to foaming and, potentially, disturbances to furnace operation. This study investigated the reduction in the slag together with its foaming using a sessile drop furnace. Five silicomanganese slags produced from industrial raw materials (Assmang ore, Comilog ore, high-carbon FeMn slag with quartz, and FeS additions) were reduced by a graphite substrate at isothermal conditions (i.e., 1540–1660 °C) under CO atmosphere. The reduction reaction was tracked by photographing the slag droplet, and the cyclic expansion and burst of the droplet were used to estimate the gas evolution. The reacted samples were analyzed by wavelength-dispersive X-ray spectroscopy (WDS) to determine MnO and SiO2 reduction. While no foaming was observed using Comilog ore, extensive retention of CO in the slag phase was observed when using Assmang ore or Assmang with high-carbon FeMn slag. The beginning of foaming was attributed to an increase in the reaction rate; the absence of foaming when using Comilog can be attributed to the acidity of the charge. Addition of sulfur to the Comilog-based charge did not influence the reduction.

Influence of Recycled Wastes on Slag Foaming during EAF Steelmaking

The potential converting the end-life product into a renewable source and replaced the conventional material found in iron and steelmaking production next tackled the world’s most problematic waste stream. Generally, integrating the waste material becomes wealth only available to certain wastes industries due to high temperature application. Recycling waste materials were introduced in order to control slag foaming in EAF steelmaking. The present paper reviews about slag foaming behaviour focused on slag droplet volume (Vt/V0 ratio), their transformation and morphology during carbon/slag interaction using sessile-drop technique at 1550°C on polymeric (HDPE), agricultural waste (palm shell), rubber tyres and metallurgical coke as the potential carbonaceous materials in EAF steelmaking. These results indicate that partial replacement of conventional materials with recycled waste materials is efficient due to improved interactions with EAF slag.

Recycling of Rubber Tyres in Electric Arc Furnace Steelmaking: Carbon/Slag Reactions of Coke/Rubber Blends

SynopsisEnd of life tyres are discarded at an alarming rate reflecting the strength of developing countries economy and the intensity of trade and transportation. Conversely, environmental concerns are increasing the need for alternative materials in steelmaking industries. The solution to this problem involves the development of environmentally-friendly technologies that would utilize these waste products. The present study investigates carbon/slag reactions, including slag foaming and FeO reduction, for a range of coke/rubber blends.Off-gas emissions (CO and CO2) were monitored and correlated with dynamic changes in volume as a result of iron oxide rich EAF slag and carbon. The gaseous emissions from metallurgical coke showed lower concentrations in comparison to the emissions from the coke-rubber blends. With an increase of rubber in the blend, gaseous emissions were enhanced. Significant carbon/slag interactions occurred when coke/rubber blends were used, with associated iron oxide reductions within the slag phase.The quantitative estimation of the slag droplet volume was performed by using the Vt/Vo ratio as a measure of slag foaming.These results indicate that partial replacement of coke with rubber is not only viable, but efficient leading to improved interactions with EAF slag.