Pulse electrorefining of magnesium metal from high temperature molten

• Main Authors: Ying-chieh Lai, 賴盈傑
• Other Authors: Chao-Chen Yang
• Format: Others
• Language: zh-TW
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/49801400470809624870

碩士 === 國立雲林科技大學 === 化學工程與材料工程系碩士班 === 102 === In this study, the magnesium metal electrodeposited by using the pulse electrolysis with the electrolyte bath of ternary system molten chlorides of NaCl-KCl-MgCl2, and the measurement and analysis of ternary system molten salt are carried out by the electrochemical cyclic voltammetry; moreover, the electrodeposition and analysis of magnesium will also be discussed. The current efficiency is respectively measured when the pulse current values are 2A, 2.5A, 3A, 3.5A and 4A, and from the analysis of these results, the pulse current value 3A and the duty cycle 50% are selected as the pulse electrolysis conditions. From the analysis of cyclic voltammetry, it shows the potential window of molten salt with adding NH4Cl tends to go up, and the result is beneficial to the reduction of magnesium and promote the magnesium metal purity. In this study, the electrolyte bath is composited by proportion of 40:60% for MgCl2-(NaCl-KCl), and the carbon rod acts as anode, and the stainless steel rod acts as cathode. The pulse electrolysis is proceeded to electrodeposite magnesium metal when the temperature of electrolysis is 937K, the pulse current value is 3A and the duty cycle is 50%, the best current efficiency obtained on the condition. However, the purity of the magnesium metal prepared by pulse electrolysis can be achieved 99%. It is the cause that when the NH4Cl is decomposed to gas phase which included NH4 and Cl2, and the electrodes are cleaned by this gas phase; moreover, the Cl2 can also increase the purity of the molten salt. So the purity of the magnesium metal is increased.