本文選題：三氧化鉬 + 二氧化鉬�。� 參考：《西安建筑科技大學》2015年碩士論文

【摘要】：鉬具有良好的物理性能,在冶金工業(yè)、電子工業(yè)、機械加工、航空航天等領域廣泛被應用。雖然有很多學者已對氫氣兩段還原制取鉬粉的工藝、動力學機理有所研究,但均為小試型實驗,與實際生產還存在較大差距。本文基于理論結合工廠實際生產,采用中試型實驗對氧化鉬氫還原過程的工藝參數及其相變、形貌演變規(guī)律進行了詳細的研究。本文通過改變還原溫度、氫氣流量、鉬舟尺寸、還原時間及料層厚度等5個影響因素,研究了兩段還原(MoO3→MoO2,MoO2→Mo)過程中還原率的變化規(guī)律,采用X-衍射分析(XRD)和掃描電子顯微鏡(SEM)對其過程和還原產物進行了表征分析。主要研究結果如下:(1)還原率均隨著還原溫度的升高而增大。溫度過高,一段易出現“過還原”和結塊現象,二段會出現“過燒”現象。兩段最佳還原溫度分別為540℃和920℃。(2)還原率隨著氫氣流量的增加而增加。氫氣超量時,還原率的變化幅度很小,還原溫度對兩段反應的還原效率占主導因素。兩段最佳氫氣流量均為1.0m3/h。(3)其它條件一定時,當料層厚度≤1/2鉬舟高度時,鉬舟壁相對料層的高度越高,還原效率越低。選擇鉬舟高度與料層厚度相當的鉬舟為宜。(4)相同還原條件且料層厚度與鉬舟高度一致,還原率隨著料層厚度的增加而減小。料層厚度對一段還原產物的物相有影響,MoO3被還原60min時,上層產物為MoO2,中層、底層物料接觸氫氣受阻礙,M4O11含量較多;70min時,上層產物出現Mo,中層、底層產物為還原良好的MoO2。(5)MoO3→MoO2是個連續(xù)還原過程,Mo4O11為中間相。MoO3→Mo4O11,Mo4O11→MoO2的雙重反應同時發(fā)生,前者反應速率高于后者。MoO2→Mo無中間相出現,其微觀形貌演變符合分裂模型。
[Abstract]:Molybdenum has good physical properties and is widely used in metallurgical industry, electronics industry, mechanical processing, aerospace and other fields.Although many scholars have studied the kinetic mechanism of two-stage reduction of hydrogen to molybdenum powder, it is a small scale experiment, and there is still a big gap with the actual production.In this paper, based on the theory and practical production in the factory, the technological parameters, phase transition and morphology evolution of molybdenum oxide reduction process are studied in detail by pilot experiment.By changing the reduction temperature, hydrogen flow rate, the size of molybdenum boat, the reduction time and the thickness of the material layer, the variation law of the reduction rate during the two-stage reduction process of Moo _ 3 / Moo _ 2 / MoO _ 2 / Moo _ 2 / Moo _ 2 was studied.The process and reduction products were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM).The main results are as follows: (1) the reduction rate increases with the increase of reduction temperature.When the temperature is too high, the phenomenon of "overreduction" and caking will occur easily in the first section, and "overburning" will occur in the second stage.The optimum reduction temperature is 540 鈩，

本文編號：1737901