Tateo Usui

Abstract:

The exhaustion of natural resources (quantity and quality) and CO₂ emission controls are becoming increasingly important in the steel industry. Several steel engineers studied various means to decrease the reducing agent at blast furnace for reduction of CO₂ emissions [1]. For example, the injection of waste plastics [2] and carbon neutral materials, such as biomass, into the blast furnace is a better alternative [3, 4]. In particular, biomass has the novel advantage of producing no CO₂ emissions, due to being carbon neutral. Production of carbon composite iron ore agglomerates that have good reducibility and strength is becoming one of the most important subjects [5]. Carbon composite iron oxide pellets using semi-char or semi-charcoal were produced from the measured results of the carbonization gas release behavior. The carbonization was done under a rising temperature condition, until arriving at a maximum carbonization temperature Tc,max to release some volatile matter (V.M.). Starting point of reduction of carbon composite pellet using semi-charcoal produced at Tc,max = 823 K under the rising temperature condition was observed at the reduction temperature TR = 833 K, only a little higher than Tc,max, which was the aimed phenomena for semi-charcoal composite pellet. As Tc,max increases, the emitted carbonization gas volume increases, the residual V.M. decreases and, as a whole, the total heat value of the carbonization gas tends to increase monotonically. The effect of the particle size of the semi-charcoal on the reduction rate was studied. When TR is higher than Tc,max, the reduction rate increases, as the particle size decreases. When TR is equal to Tc,max, there is no effect. With decreasing Tc,max, the activation energy E a of semi-charcoal decreases. The maximum carbonization temperature Tc,max may be optimized for reactivity (1/E a) of semi-charcoal and the total carbonization gas volume or the heat value.