볼밀 리프터 디자인에 의한 분쇄매체 운동 및 분쇄에너지 스펙트럼 특성 분석
Analysis of Grinding Energy Spectrum and Grinding Media Motion by Ball Mill Lifter Design
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초록
본 연구에서는 3D 기반의 DEM기법을 이용한 입자 역학 전용 해석 프로그램인 EDEM을 사용하여 볼밀 리프 터 디자인에 따른 분쇄매체의 거동 변화와 분쇄에너지 스펙트럼 특성 분석을 실시하였다. 리프터 디자인은 모양(사각 형, 반원, 사다리꼴), 길이, 개수를 변수로 설정하여 다양한 조건에서의 결과를 분석하였으며, 분쇄매체의 거동은 potential energy를 기준으로 포물선형, 중간형, 계단형 형태로 분류하여 각 조건에서 분류된 거동의 비율을 확인하였 다. 리프터의 형태가 사각형인 경우에는 포물선형 운동의 비율은 리프터의 개수가 증가할수록 감소하고, 길이가 길어 짐에 따라 점차 증가하는 형태를 보였으며, 리프터의 형태가 반원인 조건에서는 리프터의 개수와 길이가 증가할수록 포물선형 운동의 비율이 증가하였다. 사다리꼴 조건일 때의 분쇄매체의 거동은 사격형 조건의 경향성과 일치함을 보 였다. 또한 각 조건에서 face angle(면각)의 변화에 따라 포물선형 운동에 미치는 영향을 확인하였다. 결과적으로 리프 터의 면각, 모양, 길이, 개수에 따라 분쇄매체 거동의 변화를 확인하였으며, 최적의 분쇄를 위해서는 분쇄의 목적과 대 상물질에 따라 적합한 리프터의 디자인이 필요함을 확인하였다.
Abstract
In this study, the behavior change of the grinding media and grinding energy spectrum were analyzed according to ball mill lifter design using EDEM, which is an analysis program dedicated to particle dynamics using 3D based DEM technique. The lifter design was analyzed for various conditions by setting shape (square, semicircle, trapezoid), length, and number as variables. The behaviors of the grinding media were classified into cataract, intermediate and cascade based on the potential energy, and the ratios of the behaviors classified under each condition were confirmed. In the case of the square shape of lifter, the ratio of the cataract motion decreased as number of lifter increased, and gradually increased as lifter length increased. The proportion of cataract motion increased as the number of semicircle lifter numbers and length increased. In case of the trapezoid shape, the behavior of the grinding media was consistent with the tendency of the square condition. In addition, we confirmed the influence of the change of face angle on the cataract motion in each condition. As a result, changes of the behavior of grinding media were confirmed according to the shape, length, and number of lifters. For optimal grinding, it was confirmed that the design of a suitable lifter was necessary depending on the purpose of grinding and the target material.
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