菱铁矿流态化磁化焙烧机理及合理粒度上限研究
发布时间：2019-03-26 15:50
【摘要】：菱铁矿理论含铁品位低,即使作为配矿用于烧结也会因CO2析出而影响烧结强度;因而高效利用菱铁矿的唯一途径是磁化焙烧。多级循环流态化磁化焙烧克服了传统的竖炉、回转窑、沸腾炉焙烧菱铁矿存在的传热传质差、焙烧不均匀、能耗高等缺点。前人对菱铁矿流态化磁化焙烧的机理研究甚少,该技术适用的合理粒度上限尚未提出。本文利用X射线衍射、矿相显微镜、热重分析等现代检测技术对含Mg、Mn类质同像元素的菱铁矿在流态化磁化焙烧过程中的物相变化和动力学机理进行了研究;通过正交试验分析了颗粒粒度、焙烧温度、焙烧时间之间的相互关系;提出了适合菱铁矿流态化磁化焙烧的合理粒度上限。热力学分析表明:菱铁矿中类质同像的Mn CO3、Mg CO3和矿石中含有的Ca CO3在焙烧过程中不会对Fe CO3的分解产生抑制作用;反而当温度高于570℃时,CO2的扩散有助于把Fe O氧化成Fe3O4,对Fe CO3分解生成Fe3O4有利。物相转变研究结果表明:550℃、600℃、650℃Fe CO3分解产生Fe3O4,未见Fe O相出现;700℃、750℃、800℃Fe CO3分解前期产生Fe3O4和Fe O,随着焙烧时间延长Fe O转化成Fe3O4,最后Fe CO3全部转化成Fe3O4。等温动力学研究结果表明:菱铁矿流态化磁化焙烧热分解动力学符合三级化学反应控制机理模型,其活化能为156.23KJ/mol,指前因子lg A为7.6菱铁矿流化特性研究结果表明:颗粒粒度大于0.5mm以后,所需流化气体速度显著增大,其流化效果变差。正交试验表明:温度是影响菱铁矿流态化磁化焙烧转化率的主要因素,其次是粒度,然后是时间;在800℃下,大于0.3mm粒级焙烧转化率达到85%以上所需焙烧时间大于107s。物料在400Kg/h多级循环流态化磁化焙烧装置内的停留时间为90-100s,焙烧温度800℃以内适合该装置的粒度上限是0.30mm;预测60万t/a装置的粒度上限亦为0.3mm。
[Abstract]:The theoretical iron content of siderite is low, even if it is used for sintering, the sintering intensity will be affected by the precipitation of CO2, so the only way to make efficient use of siderite is magnetization roasting. The multi-stage circulating fluidization magnetization roasting overcomes the disadvantages of traditional shaft furnace, rotary kiln and fluidized bed furnace for siderite roasting, such as poor heat and mass transfer, uneven roasting and high energy consumption. The mechanism of fluidization magnetization roasting of siderite has not been studied, and the reasonable upper limit of particle size for this technology has not been put forward yet. In this paper, X-ray diffraction, metallographic microscope and thermogravimetric analysis have been used to study the phase change and kinetic mechanism of siderite containing Mg,Mn-like elements during magnetization roasting in fluidization. The relationship among particle size, calcination temperature and calcination time was analyzed by orthogonal test, and a reasonable upper limit of particle size suitable for fluidization magnetization roasting of siderite was proposed. Thermodynamic analysis shows that the isomorphous Mn CO3,Mg CO3 in siderite and the Ca CO3 contained in the ore will not inhibit the decomposition of Fe CO3 in the roasting process. However, when the temperature is higher than 570 鈩，
本文编号：2447698
[Abstract]:The theoretical iron content of siderite is low, even if it is used for sintering, the sintering intensity will be affected by the precipitation of CO2, so the only way to make efficient use of siderite is magnetization roasting. The multi-stage circulating fluidization magnetization roasting overcomes the disadvantages of traditional shaft furnace, rotary kiln and fluidized bed furnace for siderite roasting, such as poor heat and mass transfer, uneven roasting and high energy consumption. The mechanism of fluidization magnetization roasting of siderite has not been studied, and the reasonable upper limit of particle size for this technology has not been put forward yet. In this paper, X-ray diffraction, metallographic microscope and thermogravimetric analysis have been used to study the phase change and kinetic mechanism of siderite containing Mg,Mn-like elements during magnetization roasting in fluidization. The relationship among particle size, calcination temperature and calcination time was analyzed by orthogonal test, and a reasonable upper limit of particle size suitable for fluidization magnetization roasting of siderite was proposed. Thermodynamic analysis shows that the isomorphous Mn CO3,Mg CO3 in siderite and the Ca CO3 contained in the ore will not inhibit the decomposition of Fe CO3 in the roasting process. However, when the temperature is higher than 570 鈩，
本文编号：2447698
本文链接：https://www.wllwen.com/kejilunwen/kuangye/2447698.html
