Stuy On The Multipolar Cell Of Magnesium Electrolysis And Its Molten Salt’s Characteristics

There are two methods to produce magnesium:one is the thermal reduction method, the other is the electrolytic method. Currently the thermal reduction method is the main one for the magnesium production, but it has several shortcomings which are high energy consumption and large discharge amount. By comparison, the electrolytic method actualizes the continuous production under highly-automatized control and the environment friendly production process, which endow the study on the electrolytic method with significant meaning. As a new type of electrolysis cell, multipolar cell has better characteristics than the traditional electrolysis cell. However, the research and application of multipolar cell is lag, so study on the multipolar cell will contribute to the development of the magnesium production.Multipolar cell applies a new electrolyte ratio to the electrolyzation process, and there are few studies of this kind of electrolyte in China.This experiment focuses on the profound study of the physical properties of the molten salt electrolysis applied in the multipolar cell, by the extreme vertices design method selecting measuring point and through fitting curve analyzing the influence of the composition variation within the electrolyte system in the physical properties of the electrolyte applied, meanwhile design and make a small-sized multipolar cell, and electrolysis by the small-sized multipolar cell. The results are as follows:1. The liquidus temperature of the electrolyte is measured by the step-cooling curve method, the formula of liquidus temperature variation with the electrolyte composition is y=261621x1+936.52x2+522.18x3-9109.26x1x2-1051.85x1x3+1109.26x2x3.Analysising the liquidus temperature formula, it shows that the liquidus temperature increases with the increase of NaCl, and reduces with the increase of MgCl2 and CaCl2. NaCl significantly affects the liquidus temperature. In order to reduce the liquidus temperature of the electrolyte meeting the requirement of the industrial electrolysis temperature, the content of NaCl should not exceed 56%.2. The density of the electrolyte is measured by the Archimeds method, and the formula of density variation with the electrolyte composition is y=2.82x1+2.79x2+1.65x3-2.91x1X2-1.46x1X3-0.91x2X3. Through the analysis of density formula, it is noted that the density increases with the increase of CaCl2, and reduces with the increase of MgCl2 and NaCl. The CaCl2 significantly affects the density. The density of the electrolyte basically meets the requirement of the magnesium electrolysis.3. The surface tension of the electrolyte is measured by the slide method, and the formula of the surface tension variation with the electrolyte composition is y=3052.32x1+ 433.68x2+301.31x3-4986.67x1x2-4606.66x1x3-225.00x2x3. The formula of surface tension shows that the surface tension increases with the increase of MgCl2 and NaCl, reduces with the increase of CaCl2. MgCl2 significantly affects the surface tension. To protect the magnesium, the content of MgCl2 should be appropriately reduced.4. The electrical conductivity of the electrolyte is measured by absolute method, and the formula of the electrical conductivity variation with the electrolyte composition is y=8.86x1+9.82x2+3.89x3-27.59x1X2-7.41x1x3-14.63x2x3. The formula shows that electrical conductivity increases with the increase of NaCl, and reduces with the increase of MgCl2 and CaCl2-NaCl significantly affects the electrical conductivity. To increase the electrical conductivity of the electrolyte, the content of NaCl should be appropriately increased. From the analysising, we can know that we should increase the content of MgCl2, and make sure that the MgCl2 in the condition of high concentration during the electrolysising.5. Through the measured electrolysis physical properties, proving that the heating system, the electrolysis system, the inside structure and the selected materials meet the requirements of the electrolysis cell during the electrolysis. The chlorine and magnesium produced in the electrolysis chamber, and the designed multipolar cell can be applied to the magnesium production if the SiC of lining is reselection.