矿粉粒度及反应温度对高磷鲕状赤铁矿制备碳化铁的影响

基于对50根弯曲破坏钢筋混凝土圆柱低周反复试验结果的分析，建立了完整滞回环的数学表达式并推导得出等效阻尼比计算模型；以双柱墩桥梁为例，说明了建立桥梁整体结构等效阻尼比与墩柱端部塑性铰等效阻尼比关系的方法。研究表明，完整滞回环数学表达式较好地反映了弯曲破坏钢筋混凝土圆柱的滞回特性，得到的等效阻尼比模型计算结果与试验结果符合较好；采用建立的桥梁整体结构等效阻尼比与墩柱端部塑性铰等效阻尼比的关系进行pushover分析更能反映实际情况。采用等效阻尼比模型算得的目标位移与基于Rosenblueth模型和Kowalsky模型算得的位移之间存在较大差距。

Effect of hematite particle size and reaction temperature onthe preparation of iron carbide from high phosphorus oolitic hematite

In order to use high phosphorus oolitic hematite as a new raw material for steelmaking, the particle size of high phosphorus oolitic hematite and reaction temperature on the preparation of iron carbide are studied in H2-CH4 atmosphere. The weight loss of sample in reduction process, phase composition of high phosphorus oolitic hematite and carburization products are investigated by means of thermogravimetric method, SEM-EDS and XRD. The SEM-EDS and XRD analysis show that the main compositions of high phosphorus oolitic iron ore are hematite and quartz, and the main microstructure is oolitic clusters with the zonal distribution of hematite and apatite. According to the experiment results, the reaction activation energy of high phosphorus oolitic hematite with size in the range of 120~160 mesh is the lowest. In reduction step, the reaction activation energy is 44.95 kJ/mol, and the apparent reaction activation energy is 9.71 kJ/mol in carburization step. From the perspective of reaction rate, the optimum temperature for preparing iron carbide from high phosphorus oolitic hematite is 1 023 K and the optimum particle size is 120~160 mesh. Generally, compared with iron ore particle size, temperature has much more influence on the iron carbide formation from high phosphorus oolitic hematite.