Resourceful and characteristic evaluation of kish graphite in steel mill desulfurization slag

Abstract

ABSTRACT As steelmakers scale up production to meet the rising demand for steel worldwide, waste generated from steelmaking continues to increase as well. This study adopted sieve analysis and microwave digestion to explore the kish graphite content in the desulfurization slag at a steel mill in southern Taiwan. Moreover, it also explored the physical properties of desulfurization slag through various physical and chemical approaches, such as observing the surface and structure of desulfurization slag using a field emission scanning electron microscope (FE-SEM). First, the results of the sieve analysis indicated that there was 8.51% of kish graphite in the desulfurization slag, which increased substantially to 28.7% after the slag underwent acid digestion. Second, a proximate analysis showed that the desulfurization slag mainly consisted of noncombustible elements, with only a smattering of combustible content. Apart from some kish graphite, the slag was mostly composed of iron-containing materials. Finally, an FE-SEM analysis revealed that the kish graphite’s surface was covered by many impurities, mostly iron oxides, meaning that the amount of carbon content should be slightly lower if an FE-SEM analysis is conducted on kish graphite with cleaner surfaces.