Theoretical Analysis And Experimental Study For Process Of Multicomponent Powders Mixing

Powder mixture is a kind of technology which makes the processing materials being dispersed evenly in the mixing equipment to improve their characteristics.Powder mixture is widely used in food, medicine, and material, plastic and metallurgy industry. The high-efficient mixture to the powder is the support to the quality of the product and the important approach to reuse solid waste.But because of the special characteristic and the variability of powder size as well as the complexity of powder motion, the researchers can't give perfect explanations to the law of particle motion when mixture. At present, a great improvement is achieved in the research of material mixture in China and abroad. Especially, the application of numerical modeling theology greatly enriches the powder mixture field.The numerical modeling technology based on CFD can accurately predict the process of flow, heat-transfer, chemical reactions and multi-phase flow. It is widely tested and used in many different industry fields. With the rapid development of CFD and applications in industrial field, it is also a good tool to describe the pneumatic mixture process and optimal design for the structure of pneumatic homogenization storage. However, the modern cement manufacturing is a kind of typical mixing process by different chemical compositions with wide size distributions from micron to millimeter. It is not only composed with different chemical intergradient but also particles with different size. For this reason, cement is a kind of material with multiple phases. It is randomly composed by uncountable particles with different shape, size and property. A millimetre-sized particle is actually composed by uncountable micro-particles with different shape, size and property. So, this kind of powder has a dual character which is macroscopical continuity and microcosmic discretization. Because of this dual character, the pneumatic mixture flow in cement manufacturing and synthetic process is very complex. It is quite difficult to exactly predict the effects and status of cement powder in mixture process. It is also difficult to exactly test numerical simulation which is based on CFD. So at present, researchers have not yet found the best mixture process for powder. Because of lack of reasonable methods, researchers have not yet found a better method to evaluate the evenness degree of cement mixture in the actual production.In this paper, modern cement manufacturing and mix process is selected as an investigated object. On the base of review of the theory, characteristic and problems of existing powder mixture technology (including the mixture mechanism of multi-phase powder, the theory and structure of mixture equipment, evaluation method for the common mixture evenness degree and its scope of application), for the macroscopical continuity, the mixing process of cement power in the pneumatic homogenization storage is emphasized by using the multi-phase flow theories, experimentation and related Euler-Euler methods. Then the inside flow of pneumatic homogenization storage and the law of particle mixture motion is be successfully modeled by numerical simulation. The direct and complete modeling of the flow inside pneumatic homogenization storage can provide important theoretical foundation for analysis the motion law of inside particle as well as the structure optimal design and selection of real operating parameters. As the technology processes, digital image processing technology is a new method to research particle property. This method has contributed a great deal to researcher's knowledge of microscopic structure and property. The digital image processing technology is a necessary means to particle analyze. In this paper, for the microcosmic discretization, two kinds of cement powders which is composed with cement clinker and slag powder respectively are taken as sample. A large number of researches on these two samples (including properties charactering, microscopic shaping analyzing, atomic number of each intergradient of cementmixture, material micro-image processing) is done. Microscopic analysis technology is first adopted to the new evaluation method for the cement mixture evenness degree by using the technology of SEM backscattered electron image to analyze the characteristics of different intergradient of cement. The above new method is tested by industry data comparing analysis. It is effective and proved superior.