海砂矿碳热还原及强化研究
发布时间：2018-10-14 18:15
【摘要】：二氧化钛(Ti02)是电焊条表层药皮中的主要成分,在焊接过程中主要充当造渣剂的作用。海砂矿又被称为钛铁砂矿,储量丰富,且海砂矿碳热还原产物中同时含有二氧化钛和金属铁,既有二氧化钛良好造渣性能,又有铁粉提高焊条熔敷效率、改善药皮导电性能的作用,因此利用海砂矿生产电焊条用还原钛铁矿是一种提高资源利用率的有效途径。本文以澳大利亚海砂矿为原料,对海砂矿碳热还原行为进行了系统研究,同时进行了硅热、铝热强化海砂矿碳热还原实验研究。采用等温还原实验方法对海砂矿碳热还原行为进行了研究,并研究了温度和还原时间对海砂矿含碳球团还原过程中物相转变过程的影响。实验结果表明:(1)在本实验考察温度范围内,海砂矿碳热还原过程分为四个阶段。第一阶段(≤600 ℃):主要为煤粉中挥发份隔绝空气受热析出;第二阶段(600 ℃～960 ℃):主要还原反应为铁氧化物与煤粉接触发生的固-固还原,其反应速率较小;第三阶段(960 ℃～1450 ℃):主要发生气-固还原反应,此温度下碳的气化反应速率急剧加大,使得CO的含量上升,直接导致气-固还原反应速率加大;第四阶段(≥1450℃):此阶段铁氧化物的还原已基本完成。(2)得到海砂矿碳热还原的相变历程。当温度低于1100 ℃时,少量钛铁矿(FeTi03)被还原成氧化亚铁(FeO)、金属铁(Fe)和二氧化钛(Ti02),而氧化铁(Fe203)则被还原成FeO和Fe;当温度高于1100 ℃时,亚铁-假板钛矿(FeTi205)作为中间产物存在于海砂矿的碳热还原过程中,此时物相转变可表示为:FeTi03→FeTi205-→Fe+Ti02。采用添加硅铁粉和铝粉对海砂矿碳热还原进行原位强化,结果表明:(1)添加硅铁粉、铝粉能有效强化海砂矿碳热还原过程,降低氧化亚铁(FeO)含量,从而提高电焊条用还原钛铁矿产品质量;(2)提出铝热强化海砂矿碳热还原机理,当温度高于960 ℃后,铝替代部分煤粉作为还原剂参与还原反应。由于铝热还原是一个强放热过程,导致球团局部高温,加快布多尔反应和气-固还原反应的进行,从而达到强化还原的目的。(3)硅铁粉中含有的金属铁微粒,在碳热还原中可充当形核粒子,有效促进了还原过程中新生金属铁的聚集。
[Abstract]:Titanium dioxide (Ti02) is the main component in the coating of electrode, and acts as a slag-making agent in the welding process. The sea placer, also known as ferrotitanite, is rich in reserves and contains both titanium dioxide and metal iron in the carbothermal reduction products of sea placer, which not only has good slag making performance of titanium dioxide, but also has iron powder to improve the efficiency of welding rod deposition. Therefore, it is an effective way to improve the utilization of resources by using sea placer to produce reduced ilmenite for welding electrode. In this paper, the carbothermal reduction behavior of Australian sea placer is studied systematically, and the experimental study of silicothermic and aluminothermic enhancement of carbothermal reduction of sea placer is also carried out. The carbothermal reduction behavior of sea placer was studied by isothermal reduction experiment, and the effects of temperature and reduction time on the phase transition process during the reduction of carbonaceous pellets in sea placer were studied. The experimental results show that: (1) the carbothermal reduction process of sea placer is divided into four stages within the temperature range of this experiment. The first stage (鈮，
本文编号：2271240
[Abstract]:Titanium dioxide (Ti02) is the main component in the coating of electrode, and acts as a slag-making agent in the welding process. The sea placer, also known as ferrotitanite, is rich in reserves and contains both titanium dioxide and metal iron in the carbothermal reduction products of sea placer, which not only has good slag making performance of titanium dioxide, but also has iron powder to improve the efficiency of welding rod deposition. Therefore, it is an effective way to improve the utilization of resources by using sea placer to produce reduced ilmenite for welding electrode. In this paper, the carbothermal reduction behavior of Australian sea placer is studied systematically, and the experimental study of silicothermic and aluminothermic enhancement of carbothermal reduction of sea placer is also carried out. The carbothermal reduction behavior of sea placer was studied by isothermal reduction experiment, and the effects of temperature and reduction time on the phase transition process during the reduction of carbonaceous pellets in sea placer were studied. The experimental results show that: (1) the carbothermal reduction process of sea placer is divided into four stages within the temperature range of this experiment. The first stage (鈮，
本文编号：2271240
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