本文選題：赤鐵礦 + 直接還原��； 參考：《西安建筑科技大學》2015年碩士論文

【摘要】：我國的鐵礦石資源總儲量充足,但礦石品位不高,貧雜鐵礦較多,選礦難度大,常規(guī)煉鐵工藝難以實現對其高效利用。隨著富礦儲量的日益減少,未來發(fā)展的趨勢應該考慮如何實現貧鐵礦石資源的高效生態(tài)化利用,即不僅利用其中的鐵和有價金屬資源,而且還應對其中脈石組分加以有效回用。為此探索一種技術可靠、經濟合理的綜合利用技術,對實現節(jié)能減排、減少污染的資源高效化利用具有重要的現實意義和應用價值。本文以赤鐵礦為原料,以炭粉作為還原劑,進行了鐵礦石直接還原提鐵及制備膠凝材料協(xié)同研究。利用FACTSage軟件對直接還原過程進行了相關相平衡計算,探討了不同熱力學條件下的鐵礦石直接還原鐵和膠凝材料協(xié)同反應的可能性。然后采用連續(xù)升溫法和分階段升溫法進行直接還原實驗,研究了反應溫度、反應時間、還原劑配比、還原氣氛、冷卻方式對直接還原鐵還原率和膠凝材料主要成分Ca3SiO5生成率的影響,并探討了Ca3SiO5的生成機理。取得的研究成果如下:(1)對協(xié)同研究實驗的熱力學計算結果顯示,在溫度為1250℃~1450℃,碳量為理論量的0.75~1.0倍條件下,赤鐵礦中Fe2O3直接還原鐵的回收率隨碳量的增加而增大;碳量大于理論碳量時,Fe的理論還原率可以達到99%以上。在溫度低于1350℃時,理論上體系中沒有Ca3SiO5生成;在溫度為1450℃時,Ca3SiO5生成量最高達58%。此時鐵被完全還原,鐵的還原對Ca3SiO5的生成有影響。(2)連續(xù)升溫實驗溫度為1250℃~1450℃時,鐵的還原率均在90%左右;當配碳量為理論量的3倍、還原溫度為1250℃、還原時間為120min條件下,鐵的還原率高達91%。低濃度CO氣氛,不利于單質鐵生成;1250℃連續(xù)升溫實驗中,沒有檢測到Ca3Si O5生成。(3)在保證還原性氣氛下,分階段升溫實驗中設定首階段設定溫度為1000℃,保溫時間為120min,第二階段溫度1450℃,保溫時間為60min。反應同時生成了Fe和Ca3SiO5,鐵還原率為88%,Ca3Si O5含量可達42%。二價鐵離子占據Ca3SiO5的晶格,是導致Ca3SiO5難以生成的主要原因。(4)Ca3SiO5生成的適宜溫度為1450℃。冷卻速率對Ca3Si O5和Ca2Si O4的影響很大。隨爐冷卻時,由于β-Ca2Si O4晶型向γ-Ca2SiO4晶型轉變,體積增大,發(fā)生了粉化現象;快速冷卻時,由于在Ca3SiO5分解溫度1250℃和Ca2SiO4晶型轉變溫度525℃停留時間短,從而使Ca3SiO5和β-Ca2Si O4能夠保留到常溫下。鐵礦石直接還原提鐵同時制備膠凝材料在理論及實驗條件下是可行的,這對實現鐵礦石尤其是貧雜鐵礦石高效利用,緩解國內鐵礦資源壓力,節(jié)能減排提供了理論參考。
[Abstract]:The total reserves of iron ore in our country are sufficient, but the ore grade is not high, there are many poor complex iron ores, and the ore dressing is difficult, so it is difficult for the conventional ironmaking process to make efficient use of it. With the increasing decrease of rich ore reserves, the trend of future development should consider how to realize the efficient ecological utilization of lean iron ore resources, that is, to utilize not only the iron and valuable metal resources, but also the gangue components thereof. Therefore, it has important practical significance and application value to explore a kind of comprehensive utilization technology with reliable technology and reasonable economy, which can realize energy saving and emission reduction and reduce pollution. In this paper, hematite was used as raw material and carbon powder as reducing agent to study iron extraction by direct reduction of iron ore and preparation of cementitious material. The phase equilibrium of direct reduction process was calculated by FACTSage software, and the possibility of synergistic reaction between iron ore and cementitious material under different thermodynamic conditions was discussed. Then the experiments of direct reduction were carried out by means of continuous heating method and stepwise heating method. The reaction temperature, reaction time, ratio of reducing agent and reducing atmosphere were studied. The influence of cooling mode on the reduction rate of direct reduction iron and the formation rate of Ca3SiO5, the main component of cementitious material, and the formation mechanism of Ca3SiO5 were discussed. The results obtained are as follows: (1) the thermodynamic calculation results of the synergistic experiments show that the recovery rate of Fe2O3 direct reduction iron in hematite increases with the increase of carbon content at a temperature of 1250 鈩，

本文編號：1916866