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							Saburo KOBAYASHI
														
									Research Institute of Mineral Dressing and Metallurgy, Tohoku University
							 
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							Yasuo OMORI
														
									Research Institute of Mineral Dressing and Metallurgy, Tohoku University
							 
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							Koji SANBONGI
														
									Formerly Research Institute of Mineral Dressing and Metallurgy, Tohoku University