采用场发射扫描电镜和全自动压汞仪研究了石灰的晶粒大小、比表面积、孔隙等微观结构,考察了煅烧时间、温度和压力对石灰活性度的影响规律,确定石灰微观结构与石灰活性度的关系.结果表明,随石灰的比表面积、平均孔径和孔容积增加,石灰活性度先增大后减小,石灰比表面积约为2.0 m2/g、平均孔径约为850 nm、孔容积约为0.58 m L/g时石灰活性度最高.
Burnt lime is an important material in steelmaking and its activity degree is a key factor for liquid steel quality.The burnt lime was made by the calcination of limestone in a high pressure electric furnace.The burnt lime mineralogical phases and micro-morphologies were characterized by X-ray diffraction(XRD)and field emission scanning electron microscopy(FE-SEM).The burnt lime activity degree was determined by acid-base titration,the burnt lime pore distribution was measured by mercury intrusion porosimetry(MIP),and the thermal effect of a mixture of burnt lime and slag was measured by differential scanning calorimetry(DSC).The results showed that the CaO grain size and pore size of burnt lime made under high pressure were larger than those of burnt lime made under atmospheric pressure.The CaO grain size and pore size increased and the laminate phenomenon also occurred clearly under high pressure.The activity degree of burnt lime made under high pressure was greater than that made under atmospheric pressure.The maximum activity degree was 437 mL for burnt lime made under a pressure of 0.4 MPa.For the same ratio of CaO to SiO_2,the melting temperature,hemisphere temperature and fluidity temperature of slag decreased with increasing burnt lime activity degree.The higher the activity degree the burnt lime had,the better the slag forming occurred.It was advantageous for 2CaO·SiO_2and 3CaO·SiO_2 forming at lower temperatures if the burnt lime activity degree was increased.
Hua-qiang HAOYu-zhu ZHANGSu-ju HAOChao-fa ZHANGWu-feng JIANGPeng-hui CUI
