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Steelmaking slag is an attractive material because it generally contains iron oxide and free lime, which makes it able to be regarded as flux-containing low-grade iron ore for steel production. In this study, tar vapor from the pyrolysis of pine sawdust was infiltrated within porous slag and carbon deposition occurred on the pore surface by chemical vapor infiltration. For preparation, the slag sample was dehydrated in an electric furnace to decompose hydrates in the sample, creating pores. Pine sawdust was charged from bowl feeder with flowing nitrogen gas into the reactor, where it was pyrolyzed at 500 °C, rapidly producing fuel gases, tar vapor, and char. Tar vapor was introduced into the dehydrated slag and trapped inside it, where tar decomposed and carbonized within the pores. The product distribution was analyzed after the experiment. Experiments were repeated by changing the temperature and time to obtain an optimum condition for this process. The purpose of this research is to examine the amount of carbon deposited within the steelmaking slag by this tar-carbonization process. The product of this process, which is carbon-containing slag, is useful for energy reduction in steelworks.

In this paper, we describe an innovative process involving iron reduction through chemical vapor deposition for applications in the ironmaking industry. In our experiment, we produced tar vapors from pyrolysis of various solid fuels, including high-grade bituminous coal (HGC), low-grade lignite coal (LGC), and biomass palm kernel shell (PKS), and decomposed these vapors into gases, carbon, and light hydrocarbon. Carbon was deposited within the pores of pisolite ore (low-grade ore), which became porous during the dehydration process at 450 °C. We determined that the amount of tar produced during pyrolysis strongly affected carbon deposition, and HGC produced the highest carbon deposition because of its large tar product. In addition to tar amount, surface area and pore volume also played important roles in this process. PKS had the highest ratio of deposited carbon because it produced the smallest quantities of reacted tar and, consequently, the largest numbers of vacant pores. The amount of carbon deposition decreased at higher temperatures because tar was easily converted to a gaseous phase. The deposited carbon within iron ore showed potential as a reducing agent because it was highly reactive and reduced at lower temperatures. Carbon deposited within iron pores dramatically reduced the contact distance between the iron ore and carbon. Thus, these results show that our proposed methodology could have important applications as an alternative low-energy approach for producing metallic iron using low-grade materials.