(1. 東北大學(xué) 材料與冶金學(xué)院，沈陽 110819；
2. 多金屬共生礦生態(tài)化利用教育部重點(diǎn)實(shí)驗(yàn)室，沈陽 110819)
摘 要: 利用Kroll法冶煉鈦過程中還原蒸餾產(chǎn)生的熔融氯化鎂，在通氧條件下，直接熱解制備出超細(xì)的氧化鎂粉體。考察熱解溫度、熱解時(shí)間、氧氣分壓對熔融氯化鎂熱解效率的影響。通過單因素實(shí)驗(yàn)確定的最佳工藝條件如下：熱解溫度1 000 ℃，輸入氧分壓0.08 MPa，熱解時(shí)間50 min。優(yōu)化條件下氯化鎂的熱解率達(dá)93.5%。實(shí)驗(yàn)制備的樣品氧化鎂經(jīng)X射線衍射和掃描電鏡分析：其平均粒徑為80~100 nm，粒度分布均勻，分散性好，純度很高，獲得的氧化鎂顆粒為不規(guī)則六面體形。熱解反應(yīng)的動(dòng)力學(xué)研究表明：氯化鎂熱解過程的初始階段受化學(xué)反應(yīng)控制，表觀活化能為93.7 kJ/mol；反應(yīng)后期受擴(kuò)散與化學(xué)反應(yīng)混合控制，表觀活化能為26.3 kJ/mol。
關(guān)鍵字: 氧化鎂；直接熱解；熔融氯化鎂；動(dòng)力學(xué)
（1. School of Materials and Metallurgy, Northeastern University, Shenyang 110819, China;
2. Key Laboratory for Ecological Utilization of Multimetallic Mineral, Ministry of Education, Shenyang 110819, China）
Abstract:The molten magnesium chloride, from reduction-distillation process in Kroll method of titanium metallurgy, was used to produce ultra fine magnesia powder under the condition of oxygen by direct pyrolysis. The effects of pyrolysis temperature, pyrolysis time and oxygen pressure on the pyrolysis efficiency of molten MgCl2 were investigated. The single factor experiments show that the optimum reaction conditions are as follows: pyrolysis temperature 1 000 ℃, pyrolysis oxygen partial pressure 0.08 MPa and pyrolysis time 50 min. The pyrolysis rate of molten MgCl2 can reach 93.5% under the optimum conditions. The obtained MgO powder was analyzed by XRD and SEM. These MgO powders, showing an irregular hexahedral shape, have an average diameter of 80-100 nm with uniform size distribution, good dispersity and high purity. The dynamic study of pyrolysis reaction show that this reaction is controlled by chemical reaction at the initial stage of reaction, with the apparent activation energy Ea=93.7 kJ/mol. At the later reaction stage, both diffusion and chemical reaction become the restricting factors with the apparent activation energy Ea=26.3 kJ/mol.
Key words: MgO; direct pyrolysis; molten state MgCl2; dynamics
