【摘要】：二氧化鈦(Ti02)是電焊條表層藥皮中的主要成分,在焊接過程中主要充當(dāng)造渣劑的作用。海砂礦又被稱為鈦鐵砂礦,儲量豐富,且海砂礦碳熱還原產(chǎn)物中同時含有二氧化鈦和金屬鐵,既有二氧化鈦良好造渣性能,又有鐵粉提高焊條熔敷效率、改善藥皮導(dǎo)電性能的作用,因此利用海砂礦生產(chǎn)電焊條用還原鈦鐵礦是一種提高資源利用率的有效途徑。本文以澳大利亞海砂礦為原料,對海砂礦碳熱還原行為進行了系統(tǒng)研究,同時進行了硅熱、鋁熱強化海砂礦碳熱還原實驗研究。采用等溫還原實驗方法對海砂礦碳熱還原行為進行了研究,并研究了溫度和還原時間對海砂礦含碳球團還原過程中物相轉(zhuǎn)變過程的影響。實驗結(jié)果表明:(1)在本實驗考察溫度范圍內(nèi),海砂礦碳熱還原過程分為四個階段。第一階段(≤600 ℃):主要為煤粉中揮發(fā)份隔絕空氣受熱析出;第二階段(600 ℃～960 ℃):主要還原反應(yīng)為鐵氧化物與煤粉接觸發(fā)生的固-固還原,其反應(yīng)速率較小;第三階段(960 ℃～1450 ℃):主要發(fā)生氣-固還原反應(yīng),此溫度下碳的氣化反應(yīng)速率急劇加大,使得CO的含量上升,直接導(dǎo)致氣-固還原反應(yīng)速率加大;第四階段(≥1450℃):此階段鐵氧化物的還原已基本完成。(2)得到海砂礦碳熱還原的相變歷程。當(dāng)溫度低于1100 ℃時,少量鈦鐵礦(FeTi03)被還原成氧化亞鐵(FeO)、金屬鐵(Fe)和二氧化鈦(Ti02),而氧化鐵(Fe203)則被還原成FeO和Fe;當(dāng)溫度高于1100 ℃時,亞鐵-假板鈦礦(FeTi205)作為中間產(chǎn)物存在于海砂礦的碳熱還原過程中,此時物相轉(zhuǎn)變可表示為:FeTi03→FeTi205-→Fe+Ti02。采用添加硅鐵粉和鋁粉對海砂礦碳熱還原進行原位強化,結(jié)果表明:(1)添加硅鐵粉、鋁粉能有效強化海砂礦碳熱還原過程,降低氧化亞鐵(FeO)含量,從而提高電焊條用還原鈦鐵礦產(chǎn)品質(zhì)量;(2)提出鋁熱強化海砂礦碳熱還原機理,當(dāng)溫度高于960 ℃后,鋁替代部分煤粉作為還原劑參與還原反應(yīng)。由于鋁熱還原是一個強放熱過程,導(dǎo)致球團局部高溫,加快布多爾反應(yīng)和氣-固還原反應(yīng)的進行,從而達到強化還原的目的。(3)硅鐵粉中含有的金屬鐵微粒,在碳熱還原中可充當(dāng)形核粒子,有效促進了還原過程中新生金屬鐵的聚集。
[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，

本文編號：2271240