CHARACTERISTICS OF DESULFURIZATION REACTION BY SHELLS

Desulfurization characteristics of shells (scallop (Hotate), short-necked clam (Asari) and oyster (Kaki)) were studied by using a thermobalance and compared to the results obtained by limestones (Tsukumi- and Funao-Brand) currently used as desulfurizers. First, such physical and chemical properties of these samples as specific surface area, pore size distribution and chemical constituents are identified. In the thermobalance experiments the calcination temperature, the rate of temperature increase to this point, and the desulfurizing temperature are changed, and the particle diameter is fixed in the range of 297-420 mu m. After calcination is carried out in N-2 gas, the sample is sulfurized in SO2+O-2 gas in N-2 balance. The cross-sectional sulfur distribution within the reacted particle is measured by a two-dimensional XMA. Results show there is no correlation between the desulfurization efficiency and the specific surface area. However the desulfurization efficiency depends on the pore size distribution. The desulfurization efficiency of shells becomes higher than that of limestones. In the case of limestone, sulfur is only trapped near the particle surface since the micro-pores are plugged due to CaSO4. In the case of the shells, however, the sulfur is distributed over the whole body.