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首页> 外文会议>International Conference on Alternative Routes of Iron and Steelmaking ICARISM'99, Sep 15-17, 1997, Perth, WA >Efficient Utilisation of Reductant in Composite Ore-Char Pellets
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Efficient Utilisation of Reductant in Composite Ore-Char Pellets

机译：复合矿炭颗粒中还原剂的有效利用

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Direct reduction of iron ore by solid reducing agents have been studied extensively and summarised by several authors (Otsuka and Kunii, 1969; Abraham and Ghosh, 1979; Frauhan, 1977; Rao, 1971; Kawasaki, Sanscainte and Walsh, 1962; Ghosh, 1970; Rao, 1979). While studying the reduction behaviour, it is generally agreed that the reduction occurs via gaseous intermediate, generated by carbon gasification reaction which involves mass transfer, heat transfer nucleation and growth, etc through a) reduction reaction occurring at solid reductant, and b) reduction reaction occurring at solid iron oxides, thus making the overall reduction process very complex in terms of clearly defining the reduction kinetics of the system. In addition to this, practical difficulties like correctness of reaction temperature, (Seaton, Foster and Velasco, 1983) difficulties in isothermal temperature studies of reduction, difficulties in monitoring the reduction process while using gaseous reductants and separation of reduction by volatile matter from overall reduction process make the reduction kinetics more complex (Misra). Carbon present in reductants react in different manner with CO_2 due to different structural ordering of the reductants (Frauhan, 1977; Rao, 1979). Many workers have studied the effect of quantity of carbon on rate of reduction of iron oxide and have concluded that rate of reduction increases with increasing carbon content, (Otsuka and Kunii, 1969; Frauhan, 1977; Rao, 1971; Morrison, Wright and Bowling, 1978) decreasing particle size increase reduction, (Otsuka and Kunii, 1969; Rao, 1971; Morrison, Wright and Bowling, 1978; Ree and Tate, 1971; Mehrotra and Chakalder, 1989; Mukherjee, Mukherjee, Dhindaw and Ray, 1986; Seaton, Foster and Velasco, 1983; Bryk and Lu, 1986) increase in gas flowrate increases rate of reduction, (Mehotra and Chakaldar, 1989; Snehata and Ezz, 1973; Hutchings et al, 1987) etc. Hence, the net amount of carbon needed to reduce iron ore will depend upon the type of process employed. The process which leads to utilise carbon for reduction of iron ore without wasting much carbon as by product CO gas will be termed as most efficient process. In order to maximise the utilisation efficiency of carbon during reduction, composite ore-char pallets were made and fired at elevated temperature to produce composite pre-reduced pellets. These pellets consist of metallised iron core encased in a shell of partially reduced iron oxide. During reduction of such composites, a maximum value of fraction carbon reacted is achieved to be 0.8 as against the calculated value of 1.0 and such limitations are analysed on the basis of different parameters which are explained in the following lines.
机译：用固体还原剂直接还原铁矿石已被广泛研究，并由几位作者进行了总结（大冢和库尼，1969年；亚伯拉罕和戈什，1979年；弗劳罕，1977年；拉奥，1971年；川崎，Sanscainte和沃尔什，1962年；戈什，1970年） ; Rao，1979）。在研究还原行为时，通常认为还原是通过气态中间体发生的，该中间体是由碳气化反应产生的，其中涉及传质，传热成核和生长等，是通过a）固体还原剂发生的还原反应和b）还原反应由于在固态氧化铁上发生还原反应，因此，从明确定义系统的还原动力学方面来看，整个还原过程非常复杂。除此之外，还存在一些实际困难，例如反应温度的正确性（Seaton，Foster和Velasco，1983年），难以进行还原的等温温度研究，难以在使用气态还原剂的同时监测还原过程，以及通过从整体还原中分离出挥发性物质来还原还原反应。过程使还原动力学更加复杂（Misra）。由于还原剂的结构顺序不同，还原剂中存在的碳以不同的方式与CO_2反应（Frauhan，1977； Rao，1979）。许多工人研究了碳含量对氧化铁还原速率的影响，并得出结论，还原速率随碳含量的增加而增加（（Otsuka和Kunii，1969； Frauhan，1977； Rao，1971； Morrison，Wright和Bowling） （1978）；减小粒度增加减小（Otsuka和Kunii，1969； Rao，1971； Morrison，Wright和Bowling，1978； Ree和Tate，1971； Mehrotra和Chakalder，1989； Mukherjee，Mukherjee，Dhindaw和Ray，1986；和1986）。 Seaton，Foster和Velasco，1983; Bryk和Lu，1986）的增加增加了天然气流量的减少率（Mehotra和Chakaldar，1989; Snehata和Ezz，1973; Hutchings等，1987）等。还原铁矿石所需的碳取决于所采用的工艺类型。导致利用碳还原铁矿石而又不浪费太多碳的过程，因为副产物CO气体被称为最有效的过程。为了使还原过程中碳的利用效率最大化，制得了复合矿石炭托盘并在高温下进行烧制，以生产复合的预还原颗粒。这些颗粒由包裹在部分还原的氧化铁壳中的金属化铁芯组成。在这种复合材料的还原过程中，反应的碳分数的最大值相对于计算值1.0达到了0.8，并且根据不同参数分析了这些限制，这些参数在以下各行中进行了说明。

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