Extracting Of Metal And Oxygen From Ilmenite And Lunar Soil Simulant Composite Oxides

More and more attention was focused on lunar exploration and development because there is abundant energy and rich mineral resources on the moon,and metals and oxygen can be obtained using in-situ resource utilization technologies,which is of great importance in scientific research.By process of aluminothermic reduction in cryolite molten salt media-molten salt electrolysis using inert anode,the lunar soil consisting of mixed oxides such as ilmenite and anorthite can be used as raw materials to prepare metal and oxygen.The solubility of TiO2 and FeTiO3 in 51.22mass%NaF-48.78mass%AlF3 molten salt at 980 ? was studied by isothermal saturation method.The result indicates that TiO2 concentration in cryolite molten salt can reach the saturated value 3.2mass%after 90 minutes's dissolving by adding TiO2 squash to the cryolite molten salt,while by adding FeTiO3 squash to the cryolite molten salt,FeTiO3 concentration in cryolite molten salt can reach the saturated value 3.7mass%after 120 minutes's dissolving.The most probable titanium species dissolved in cryolite molten salt is titanium oxyfluoride complex ion,while the Fe(?)and Fe(?)species dissolved in cryolite molten salt are both iron fluorine compounds.The standard Gibbs free energy change of aluminothermic reduction of ilmenite was calculated.The result shows that standard Gibbs free energy changes are all negative at temperature range of 0-1500?.The result of DSC analysis shows that the aluminothermic reduction of ilmenite starts at about 951?,the apparent activation energy of the reaction is 9164.23J/mol,and the reaction order is 0.11.The effects of reductant amount and reaction time on the aluminothermic reduction of ilmenite in 48.66mass%NaF-46.34mass%AlF3-5.00mass%FeTiO3 molten salt at 980? were studied.The results obtained by XRF,XRD,SEM and EDS analysis show that the products mainly contain Al,Ti,Fe,and little Si,and the main phase of the product is Al3Ti.With the increase of reductant amount,the content of Ti in alloy products decreases,while the content of Fe in alloy products increases.In addition,the content of Al3Ti increases with the increase of reaction time.The highest content of Ti in the alloy obtained by aluminothermic reaction for 2h at 980? using 3 times reductant amount of theoretical amount is up to 18.82 mass%.The chemical composition,microstructure and phase distribution of the alloy product obtained by enlargement aluminothermic experiment are consistent with characteristics and laws of single factor experiment described above.The cathodic product obtained by electrolysis using cyathiform inert anode contains 90.72mass%Al,6.79mass%Fe,1.31mass%Ti,0.97mass%Si,and 0.21mass%Ni,while the purity of anodic gas oxygen reaches 98.87%.The cathodic alloy product obtained from single factor electrolysis experiment of current density in 48.66mass%NaF-46.34mass%AIF3-5.00mass%FeTiO3 molten salt at 980 ?contains 62.18-74.96mass%Al,19.02?29.5 1mass%Fe,4.14-5.44mass%Ti,0.36-0.96mass%Ni,and the main phases of alloy are Al,Al3Fe and Al3Ti.Microstructure analysis showed that the alloy product is mainly in the form of aluminum body,massive Al3Fe phase and strip Al3bTi phase.The apparent cathodic current efficiency ranges from 40.12%-45.63%.The purity of anodic gas oxygen obtained from single factor experiment of current density is above 97%.The anodic current efficiency ranges from 71.62%-80.47%,which linearly increases with the increasement of current density.The dense and complete oxide layer was formed at the surface of Fe0.58-Ni0.42 alloy anode during electrolysis,which reveals good combination with the anode substrate.The oxide layer thickness is about 200?m,and the Fe0.58-Ni0.42 alloy anode exhibit good inertly during electrolysis.Al-Si master alloy and oxygen were prepared by the process of aluminothermic reduction in cryolite molten salt media-molten salt electrolysis using Fe0.58-Ni0.42 alloy inert anode through the 48.66mass%NaF-46.34mass%AlF3-5mass%MLS-1 molten salt.The recovery ratio of Si,Fe and Ti of overall process are 95.34%,89.94%and 86.83%,respectively.The purity of anodic gas oxygen reaches 99.02%.