Jianguo Yu

Catalytic Graphitization of Coal-Based Carbon Materials with Light Rare Earth Elements

The catalytic graphitization mechanism of coal-based carbon materials with light rare earth elements was investigated using X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, selected-area electron diffraction, and high-resolution transmission electron microscopy. The interface between light rare earth elements and carbon materials was carefully observed, and two routes of rare earth elements catalyzing the carbon materials were found: dissolution-precipitation and carbide formation-decomposition. These two simultaneous processes certainly accelerate the catalytic graphitization of carbon materials, and light rare earth elements exert significant influence on the microstructure and thermal conductivity of graphite. Moreover, by virtue of praseodymium (Pr), it was found that a highly crystallographic orientation of graphite was induced and formed, which was reasonably attributed to the similar arrangements of the planes perpendicular to (001) in both graphite and Pr crystals. The interface between Pr and carbon was found to be an important factor for the orientation of graphite structure.

Synergistic catalytic effect of light rare earth element and other additives on the degree of graphitization and properties of graphite

Metal additives usually have a catalytic effect on non-graphitic carbon materials. However, graphitic carbon materials are difficult to catalyze owing to carbon atoms whose neighbors are ordered regions and less cross-linked. Artificial graphite is generally prepared from coke and pitch, both of which are graphitic carbon. Therefore, efficient catalysts for graphitic carbon materials are important for industrial technology. The effect of light rare earth elements (La, Ce, and Pr) and other additives (Ti, Ni, and B) as co-catalysts in artificial graphite development was investigated. Compared with the single catalysts, the combinatorial catalysts more significantly improved the degree of graphitization in the carbon materials, indicating synergistic catalytic effects. Both dissolution–precipitation and formation–decomposition of carbide were involved in the synergistic catalytic mechanisms. In the combinatorial catalysts systems, the light rare earth element would accelerate the graphitization process of carbon materials by widening the range of the catalytic temperature, accelerating the speed of oversaturation of dissolution, or generating a new carbide phase with the other catalyst. This would promote formation of the more-ordered graphitic structure at relatively low temperature. For instance, to attain the same degree of graphitization and better crystalline sizes at the same residence time, the carbon materials with combinatorial catalysts can be heat treated at temperatures 400xa0°C lower than without catalysts, and the electrical and mechanical properties are enhanced.

Magnesium electrolyzer structural optimization based on energy balance

The diaphragmless magnesium electrolyzer was the main equipment for molten salt electrolysis to produce magnesium. The major energy-consuming in production process was electric energy. With the continuous development of science and technology, reducing energy loss had attracted peoples attention. In this paper, in order to obtain the electrolyzer with the structure of high capacity and low energy consumption, the structural parameters of electrolyzer were changed on the basis of energy balance equation, and the factors affecting electrolyze were analyzed and summarized.

Study Flow Field of Magnesium Electrolyzer by Computer Technology

In modern times, computer technology is used in various fields in the world. In this paper, CFD(computational fluid dynamics) was applied to build mathematical model to simulate continuous and dispersed multiphase flow in the experimental systems and an industrial electrolyzer. The Volume of Fluid model was used in the mathematical model for multi-phases. Cold model system of complex multiphase behavior of argon gas, water and silicon oil system in terms of dynamic similarity was established to validate the math model. Flow field was measured through PIV (particle-image velocimetry) technology. The results show that the built three dimensional mathematical model was valid for the system and suitable for the electrolyzer in electrolysis magnesium industry. The characteristics of complex multiphase in industrial electrolyzer were discussed in the paper.

Applications of Computer in Engineering Especially in Electrolysis Magnesium Industry

In modern times, computers have closely connection with everyone, especially scientist and engineer. Computer programs can now solve difficult problems in a fraction of the time it used to take. Computer-Aided engineering is a powerful tool and necessary for engineering design and manufacture. Nowadays, you no longer have to write your own software programs to use computers effectively. In chemical engineering, a lot of softwares are used in the process of chemical operation, Such as the software for process of chemical engineering Pro¿ and Aspen, and Computational fluid dynamics software Fluent and CFX and so on. The details of the process and unite operation can be investigated by computer and software. During electrolysis magnesium, high temperature and airproofed operation condition prevent the study of fluid phenomena in the electrolytic cell.xa0xa0The computational fluid dynamics can overcome these difficulties. Details of the flow field of electrolytic cell can be visualized on the computer screen. Through the visualization, flow field of electrolytic cell and the factors that affect the electrolysis process can be investigated.