【摘要】：菱鐵礦理論含鐵品位低,即使作為配礦用于燒結(jié)也會因CO2析出而影響燒結(jié)強度;因而高效利用菱鐵礦的唯一途徑是磁化焙燒。多級循環(huán)流態(tài)化磁化焙燒克服了傳統(tǒng)的豎爐、回轉(zhuǎn)窯、沸騰爐焙燒菱鐵礦存在的傳熱傳質(zhì)差、焙燒不均勻、能耗高等缺點。前人對菱鐵礦流態(tài)化磁化焙燒的機理研究甚少,該技術(shù)適用的合理粒度上限尚未提出。本文利用X射線衍射、礦相顯微鏡、熱重分析等現(xiàn)代檢測技術(shù)對含Mg、Mn類質(zhì)同像元素的菱鐵礦在流態(tài)化磁化焙燒過程中的物相變化和動力學機理進行了研究;通過正交試驗分析了顆粒粒度、焙燒溫度、焙燒時間之間的相互關(guān)系;提出了適合菱鐵礦流態(tài)化磁化焙燒的合理粒度上限。熱力學分析表明:菱鐵礦中類質(zhì)同像的Mn CO3、Mg CO3和礦石中含有的Ca CO3在焙燒過程中不會對Fe CO3的分解產(chǎn)生抑制作用;反而當溫度高于570℃時,CO2的擴散有助于把Fe O氧化成Fe3O4,對Fe CO3分解生成Fe3O4有利。物相轉(zhuǎn)變研究結(jié)果表明:550℃、600℃、650℃Fe CO3分解產(chǎn)生Fe3O4,未見Fe O相出現(xiàn);700℃、750℃、800℃Fe CO3分解前期產(chǎn)生Fe3O4和Fe O,隨著焙燒時間延長Fe O轉(zhuǎn)化成Fe3O4,最后Fe CO3全部轉(zhuǎn)化成Fe3O4。等溫動力學研究結(jié)果表明:菱鐵礦流態(tài)化磁化焙燒熱分解動力學符合三級化學反應(yīng)控制機理模型,其活化能為156.23KJ/mol,指前因子lg A為7.6菱鐵礦流化特性研究結(jié)果表明:顆粒粒度大于0.5mm以后,所需流化氣體速度顯著增大,其流化效果變差。正交試驗表明:溫度是影響菱鐵礦流態(tài)化磁化焙燒轉(zhuǎn)化率的主要因素,其次是粒度,然后是時間;在800℃下,大于0.3mm粒級焙燒轉(zhuǎn)化率達到85%以上所需焙燒時間大于107s。物料在400Kg/h多級循環(huán)流態(tài)化磁化焙燒裝置內(nèi)的停留時間為90-100s,焙燒溫度800℃以內(nèi)適合該裝置的粒度上限是0.30mm;預(yù)測60萬t/a裝置的粒度上限亦為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，

本文編號：2447698