煤泥和高炉灰在高磷鲕状赤铁矿直接还原中的作用及机理

发布时间：2018-03-25 20:17

  本文选题：高磷鲕状赤铁矿　切入点：煤泥　出处：《北京科技大学》2017年博士论文

【摘要】：高磷鲕状赤铁矿是公认难选的铁矿石类型之一。近年来研究表明,采用煤基直接还原焙烧-磁选工艺可有效处理该类矿石。煤泥是选煤过程中产生的一种副产品,因为它具有水分含量高、粘性大、灰分含量高的缺点,所以较难被利用。高炉灰是钢铁工业的副产品,具有既含碳也含铁氧化物的特点,但因无行之有效的利用途径,大部分被室外堆存,既造成了环境污染也造成了铁资源的浪费。本文研究了煤泥和高炉灰作为高磷鲕状赤铁矿直接还原焙烧中还原剂的可行性。考察了不同种类的煤泥在高磷鲕状赤铁矿直接还原焙烧中的作用及机理,并获得了最佳工艺条件。结果表明,煤泥T的还原效果最好,在其用量为20%时可获得铁品位为91.35%,铁回收率为81.13%,磷含量为0.076%的还原铁产品。高炉灰与高磷鲕状赤铁矿共还原是可行的,既利用了高炉灰中的碳,也同时回收了高炉灰和高磷鲕状赤铁矿中的铁,实现了高炉灰和高磷鲕状赤铁矿共同利用的目的。通过对脱磷剂用量、焙烧时间、焙烧温度、高炉灰用量的研究,获得了最佳工艺条件。结果表明,在高炉灰用量为30%,焙烧温度为1150℃,焙烧时间为60min的焙烧条件下,焙烧产品经两段磨矿-磁选,可获得铁品位92.16%,铁回收率87.89%,磷含量0.072%的还原铁产品。同时发现脱磷剂CaCO_3可以降低还原铁产品的磷含量,Na_2CO_3可以提高铁回收率。发现高炉灰在C/Fe比为1.04已可以完成与高磷鲕状赤铁矿的共还原,并且发现在高炉灰作为还原剂时焙烧效果优于煤的。用X射线粉晶衍射、扫描电子显微镜及能谱分析对煤泥和高炉灰在高磷鲕状赤铁矿直接还原焙烧过程中的作用机理进行了研究。.发现,煤泥灰分中的石英在还原气氛充足时对氟磷灰石的还原具有促进作用,结果导致还原铁产品中的磷含量升高。煤泥中的挥发分在还原过程中起作用,能够提高还原铁的铁回收率,但对降低还原铁产品中的磷含量不利。引入C/Fe比的概念,查明了高炉灰在共还原焙烧中的反应机理,即高炉灰与高磷鲕状赤铁矿更易发生固相-固相反应,而煤在此条件下更易发生气相-固相反应。固相-固相反应有利于提高铁回收率和降低还原铁中的磷含量,而气相-固相反应则不利于降低还原铁中的磷含量。
[Abstract]:High phosphorous oolitic hematite is recognized as one of the difficult iron ore types. Recent studies have shown that coal based direct reduction roasting and magnetic separation process can effectively treat this kind of ore. Coal slime is a by-product of coal preparation process. Because of its high moisture content, high viscosity and high ash content, blast furnace ash is difficult to be used. Blast furnace ash is a by-product of iron and steel industry and has the characteristics of both carbon and iron oxides, but it has no effective way to use it. Most of it is stored outdoors, This paper studies the feasibility of coal slime and blast furnace ash as reducing agent in direct reduction roasting of high phosphorous oolitic hematite. The role and mechanism of direct reduction roasting of iron ore. The optimum technological conditions are obtained. The results show that the reduction effect of slime T is the best. Iron grade is 91.35, iron recovery rate is 81.13 and phosphorus content is 0.076%. Co reduction of blast furnace ash with high phosphorous oolitic hematite is feasible. At the same time, the iron from blast furnace ash and high phosphorous oolitic hematite was recovered, and the purpose of co-utilization of blast furnace ash and high phosphorous oolitic hematite was realized. The amount of dephosphorization agent, calcination time, calcination temperature and amount of blast furnace ash were studied. The optimum technological conditions are obtained. The results show that under the conditions of 30% ash content, 1150 鈩，

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