赤泥中铁资源的回收利用研究

Study on Comprehensive Utilization of Iron from Red Mud

系统概述了目前国内外赤泥中铁回收利用技术和应用。对澳大利亚赤泥进行了还原焙烧—磁选、熔炼生铁工艺试验。分析了赤泥及还原焙烧样微观显微镜下铁元素的赋存状态和分布情况。阐明了还原焙烧时赤泥中绝大部分赤铁矿或磁赤铁矿等各类氧化铁已完成向金属铁的转变,但各类铁矿物与非晶态的铁尖晶石关系过于密切且嵌布特征十分复杂,焙烧后细磨无法使二者充分解离,因此不易获得高品位铁精矿。在焦比20%、熔炼时间90min、钙铝比2.0、1500℃进行赤泥还原熔炼,可实现渣铁的有效分离,金属铁回收率可达到99.4%以上,所得铁水质量符合炼钢生铁标准。在碳酸钠100g/L、液固比10∶1、温度80℃、时间1.5h下进行自粉化熔渣中铝的浸出,Al2O3浸出率达到91.12%。

Common process routes and research status of extraction and recovery of iron from red mud at home and abroad were introduced.Red mud from Australian was tested by reduction roasting and magnetic separation,and melting iron process.Following microscopic observations,the vast majority of hematite and maghemite change into metallic iron during roasting.However,further treatment of roasted material to iron ore concentrate through milling and magnetic separation was not successful due to highly intergrown nature of reduced material with spinel phases.Metal iron yield is 99.4%above,and quality of molten iron meets the requirements of steelmaking under the optimum conditions including ratio of coke of 20%,reduction smelting time at 1 500℃of 90 min,and ratio of calcium oxide to alumina of 2.0,which can achieve effective separation of slag and iron.The slag can be disintegrated completely.Alumina leaching ratio is 91.12%from the slag under the conditions including dosage of Na 2CO 3 of 100 g/L,L/S=10/1,temperature of 80℃,and leaching time of 1.5 h.