改善预热球团矿抗压强度的工艺优化

Process Optimization for Improving Compressive Strength of Preheated Pellets

为了改善预热球团矿的抗压强度,结合生产实践经验,模拟链篦机-回转窑工艺制度,采用正交实验法分析了影响预热球团矿抗压强度的因素及工艺改进措施。结果表明,OA矿和OB矿粒度较细,-0.074 mm粒级含量大于85%,能满足造球粒度基本要求;90%OA矿搭配10%OB矿时,经过干燥、预热工艺段,球团矿FeO含量可以从26%降低到4%以下,氧化度大于85%;提高预热球团矿抗压强度的适宜链篦机热工参数为:鼓风干燥温度200℃、抽风干燥温度360℃、预热Ⅰ段温度720℃、预热Ⅱ段温度990℃,此条件下预热球团矿抗压强度可达1056 N/球;验证实验符合预期结果。

Based on the experience from production practices,an orthogonal experiment was performed by simulating a grate-rotary kiln process to investigate factors affecting compressive strength of preheated pellets and also find measures to improve the process.It is found that both OA iron ore and OB iron ore are fine-grained,with-0.074 mm grain content greater than 85%,which meets the basic requirements for particle size in pelletizing process.With 90%OA iron ore blended with 10%OB iron ore,the obtained pellet after drying and preheating process can have FeO content reduced from 26%to less than 4%,with the oxidation degree greater than 85%.With the following optimal thermal parameters of chain grate,including a drying temperature of 200℃for air blowing and a drying temperature of 360℃for ventilation,720℃for I-stage preheating and 990℃for II-stage preheating,the obtained preheated pellet can have a compressive strength of 1056 N/pellet.It is verified that the experimental result is in accordance with the anticipation.