Among the raw material production industries that use a large amount of limestone, the effectiveness of limestone usage in the steel production industry has been evaluated and the optimization of limestone addition ratio has been investigated. Based on the past research and development results concerning the CaO added basic sinter production technology, the phenomena of permeability deterioration caused by the excessive CaO addition and the actual operation tests, the multi-component calcium ferrites (SFCA) in sinter that have been currently intensively researched and developed have been evaluated. The reducibility of sinter in blast furnace has so far focused on the lumpy zone up to 1000 °C, but in the future research, it will be necessary focused on the reducibility and permeability in the cohesive zone up to 1000~1500 °C. The current chemical compositions of SFCA has the good reducibility and permeability in the cohesive zone, but the research and development are needed to maintain the appropriate range of CaO (CaO/SiO2 = 1.5~2.0) and further to improve the reducibility and permeability. The future progress of the research and development has been presented.

Scandium (Sc) generally lacks independent deposits and is mainly recovered as a by-product of the smelting of other ores. Scandium is present in laterite ores in concentrations ranging from tens to hundreds of ppm. In the process of recovering nickel from laterite ores, Sc is recovered from sulfuric acid leachates. An ion-exchange resin method is an effective way to recover low concentrations of Sc (III) in sulfuric acid leachates. In our previous studies, the adsorption behaviors of Sc (III) and other trivalent metal ions were investigated, but the desorption behaviors of them were not. This study proposes optimal adsorption and desorption conditions for the selective separation and recovery of Sc from other trivalent cations in sulfuric acid solutions using an iminodiacetic acid chelating resin, Diaion™ CR11. The chelating resin with each metal ion adsorbed was mixed with sulfuric acid solution, and the desorption behaviors of these ions were investigated. On the other hand, adsorption tests were conducted using the chelating resin with residual Cr (III). The order of ease of desorption was Al (III) > Sc (III) > Fe (III) >> Cr (III). The desorption reaction rate of Cr (III) increased with increasing temperature, and its activation energy was estimated to be 82 - 93 kJ mol-1. Although the adsorption reaction rate and the amount of Sc (III) decreased with increasing residual amount of Cr (III) on the chelating resin, the adsorption ratio of Sc (III) was over 90% at a bed volume of 30 in a column test at 23˚C using the chelating resin with a residual amount of Cr (III) of 0.2 mmol g-1. With appropriate adsorption and desorption operations, scandium in laterite ores can be recovered continuously and efficiently, contributing to the development of the industry.