Browsing by Author "Dong, A."
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Item Beneficial and technological analysis for the recycling of solar grade silicon wastes(2011) Dong, A.; Zhang, L.; Damoah, L.N.W.In the current paper, different kinds of silicon wastes during the production of SoG-Si were summarized and the beneficial analyses, such as financial value, energy value, CO2 emissions, and efficiency and energy payback time, were briefly discussed for the recycling of SoG-Si wastes. Possible technologies to recycle and purify SoG-Si wastes were reviewed: such as filtration, sedimentation, solidification control, electromagnetic separation, plasma oxidation, centrifugation, and high temperature remelting process, et al.Item Entrapment of inclusions in continuous casting billet: Industrial observation and modeling(AIST – Association for Iron and Steel Technology, 2010) Wang, Y.; Zuo, X.; Zhang, L.; Li, S.; Dong, A.; Damoah, L.N.W.Item Non-Metallic Particles in Solar Grade Silicon (SoG-Si)(IEEE, 2010) Damoah, L.N.W.; Dong, A.; Zhang, L.; Zhu, H.; Wang, C.This study investigated the non-metallic inclusions in Solar 2rade Silicon (SoG-Si), especially the distribution of inclusions in the top 15mm layer of multicrystalline silicon ingot. The SoG-Si ingot produced from directional solidification process usually pushes the impurities to the top and finally cut off and discarded, which leads to material loss. The hard inclusions lead to wire breakages during the cutting of the ingot into wafers. The main kinds of inclusions found in top-cut silicon scraps from two manufacturers have been investigated using acid extraction, automated feature analysis techniques and SEM-EDS and optical Microscope: they are needle-like Si3N4 and lumpy SiC inclusions. Surface observations of the scraps before polishing revealed that, Si3N4 inclusions are usually bigger and in some cases can be about a few millimeters. SiC inclusions are usually smaller, ∼200μm but can be ∼500μm in some cases. F or the directional solidified silicon ingot, it was determined that an approximate distance of ∼10mm is a good enough cutoff thickness.Item Purification of solar grade silicon using electromagnetic field(IEEE, 2010) Dong, A.; Damoah, L.N.W.; Zhang, L.; Zhu, H.Non-metallic particles and the metallic impurity elements in the solar cell silicon have a strong detrimental effect on the conversion efficiency of the solar cell. Removing these impurities is one of the important tasks for silicon refining. The current paper proposed a new approach to purify silicon - electromagnetic (EM) separation. Since the non-metallic particles and the metallic impurity elements are non- or less-conductive while the molten silicon is well conductive, under EM field, the Lorenz force will push the particles to the boundary layer, thus separate these inclusions. In the current study, a high frequency EM field was imposed on the silicon melt in laboratory scale experiments with a frequency of 60 kHz and 15.0 A current, the non-conductive SiC particles were successfully pushed to the boundary layer close to the crucible wall.Item Removal of inclusions from solar grade silicon using electromagnetic field(John Wiley & Sons, Inc., 2011) Dong, A.; Damoah, L.N.W.; Zhu, H.; Zhang, L.; Wang, C.The characteristics of the top-cut solar grade silicon (SoG-Si) scraps produced from SoG-Si ingots were investigated using optical microscope observation, SEM-EDS analysis and automatic inclusion scanning (ASPEX). Particles of SiC and Si3N4 are the main non-metallic inclusions in the SoG silicon top-cut scrap. The deeper into the scrap from the surface, the less and smaller inclusions are found. A laboratory-scale electromagnetic purification unit was used to melt the silicon scraps and remove inclusions from the melt. The experimental results indicated that the electromagnetic (EM) field efficiently pushed the non-metallic particles and less-conductive metallic impurity elements to the boundary layer.