(1. 武漢科技大學 鋼鐵冶金新工藝湖北省重點實驗室，武漢 430081；
2. 武漢科技大學 省部共建耐火材料與冶金國家重點實驗室，武漢 430081；
3. 北京科技大學 鋼鐵冶金新技術國家重點實驗室，北京100083；
4. 佛山(華南)新材料研究院，佛山 528200)
摘 要: 純氧條件下對輝鉬精礦的氧化焙燒行為展開基礎研究，并結合最佳模型擬合法、TG-DTA、SEM-EDS和熱力學軟件FactSage 7.3等方法和手段對實驗結果進行分析。結果表明：精礦在723 K和773 K下不能完全氧化，然而當溫度升至873 K時，精礦能完全氧化生成三氧化鉬(MoO3)。在較高溫度下，如873 K和773 K時，精礦的氧化焙燒過程由界面化學反應控速；然而在較低溫度下，如723 K時界面化學反應和形核長大模型共同發(fā)揮作用。反應過程中，產(chǎn)物由初始顆粒形態(tài)逐漸轉變成具有層狀結構的片狀形貌，并且在晶面指數(shù)(020)、(040)、(060)和(0100)等晶面上衍射峰強度顯著增加，表明生成的MoO3具有一定的各向異性和擇優(yōu)長大傾向。輝鉬精礦的氧化焙燒過程符合揮發(fā)-冷凝機理，期間伴隨著少量中間產(chǎn)物二氧化鉬(MoO2)的生成。焙燒過程中產(chǎn)生的燒結現(xiàn)象是局部溫度的升高和低熔點共晶體的形成共同作用所致。結合熱力學數(shù)據(jù)本文還理論分析了主要雜質元素在焙燒過程中的演變規(guī)律及其對燒結行為的影響機制，并提出有效降低燒結現(xiàn)象發(fā)生的可行方案。
關鍵字: 輝鉬精礦；氧化焙燒；三氧化鉬；燒結現(xiàn)象
（1. Hubei Provincial Key Laboratory for New Processes of Ironmaking and Steelmaking, Wuhan University of Science and Technology, Wuhan 430081, China;
2. The State Key Laboratory of Refractories and Metallurgy, Wuhan University of Science and Technology, Wuhan 430081, China;
3. State Key Laboratory of Advanced Metallurgy, University of Science and Technology Beijing, Beijing 100083, China;
4. Foshan (Southern China) Institute for New Materials, Foshan 528200, China）
Abstract:The current work focus on the oxidation roasting behavior of molybdenite concentrate in high-purity oxygen atmosphere on the basis of the authors’ previous paper. The best modeling fit, TG-DTA, SEM-EDS and thermodynamic calculation method were adopted to analyze the experimental data. The results show that molybdenite concentrate cannot be reacted completely at 773 K and 723 K; when the temperature is increased to 873 K, however, the raw material can be oxidized to molybdenum trioxide (MoO3) completely. Combining the normalization and model fit methods, the work concludes that the rate-controlling step for the oxidization of molybdenite concentrate in the range of 773 K to 873 K is the interfacial chemical reaction. When the temperature is below 773 K, however, interfacial chemical reaction and nucleation and growth models both worked. It is also found that the morphology of obtained product transforms from previous particle shape to the final needle-like structure during the whole reaction process. XRD patterns show that the obtained needle-like product has an intense diffraction peak for the crystal indices of (020), (040), (060), and (0100), indicating its anisotropy and prior growth up tendency. Oxidation roasting processes of molybdenite concentration obey the vaporization- condensation mechanism with the formation of molybdenum dioxide (MoO2) as the intermediate product is also obtained. The study results also conclude that the occurrence of sintering phenomenon are due to the combined actions of the increase of local temperature and the formation of low-melting-point eutectics during the roasting process. With the help of FactSage 7.3 thermodynamic software, the transformation laws of the main impurities components and its effect on the sintering phenomenon during the roasting processes were also theoretically analyzed. The current work may play positive roles on understanding the roasting behavior of molybdenite concentrate and improve the service life of multiple heart furnaces.
Key words: molybdenite concentrate; oxidation roasting; molybdenum trioxide; sintering phenomenon
