ABSTRACT

The reduction of an Indonesian iron sand concentrate was studied using TG/DTA and XRD analyses. The iron sand concentrate was mixed with coal and formed into a cylindrical pellet. The experimental results show that magnetite was reduced into wustite at 700–800°C and into metallic iron at temperature above 800°C. The transformation of titanomagnetite into ulvospinel and ilmenite occurred between 900 and 1000°C, and ulvospinel transformed into ilmenite and iron at 1000–1100°C. To simulate the reduction process in a rotary kiln, iron sand concentrate pellets were hardened at 1250°C and reduced using coal, which was added to cover the surface of the pellet at a temperature range of 800–1100°C for 150 min. The reduction degree was calculated based on the weight loss and the metallization degree was determined by wet chemical analysis. Quasi-equilibrium values of the reduction and metallization degrees were obtained at a certain temperature. The reversible first-order kinetics equation was proposed to analyse the experimental data to predict the metallization degree as a function of the reduction time and temperature.

摘要

使用 TG/DTA 和 XRD 分析研究了印度尼西亚铁砂精矿的还原。铁砂精矿与煤混合并形成圆柱形球团。实验结果表明，磁铁矿在 700-800°C 时被还原为方铁体，在 800°C 以上时还原为金属铁。钛磁铁矿在 900 到 1000°C 之间转变为钛尖晶石和钛铁矿，而在 1000 到 1100°C 之间，铝尖晶石转变为钛铁矿和铁。为了模拟回转窑中的还原过程，铁砂精矿球团在 1250°C 下硬化并使用煤还原，在 800-1100°C 的温度范围内加入煤以覆盖球团表面 150 分钟。基于重量损失计算还原度，通过湿化学分析确定金属化度。在一定温度下获得还原度和金属化度的准平衡值。提出了可逆一级动力学方程来分析实验数据，以预测金属化程度作为还原时间和温度的函数。