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DEM 계산력 변수에 의한 교반분쇄볼밀의 분쇄속도상수 연구
김성수(S.S. Kim),박기태(G.T. Park),정한식(H.S. Chung),최희규(H.K. Choi) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.5
In study of grinding mechanism, theological equations for grinding process have been used which are based on material balance. The solution of such equations are generally not given. To study for grinding rate K of a stirred ball mill, it was simplified and conditioned to calculate movement of all balls by using DEM (Discrete Element method) simulation. The grinding rate K is expressed as K=a exp(bn) by experiments. To identify relation between K and DEM simulation results, as new conception, calculate force F<SUB>cal</SUB> are introduced and it is defined as F<SUB>cal</SUB> = average force acting on one ball x coordination number. With F<SUB>cal</SUB>, grinding rate K could be expressed as K = a'F<SUB>cal</SUB>+ b'.
cake-less 고농축 연속여과시스템의 연구개발 (3)
최희규(H. K Choi),정한식(H. S Chung),정효민(H. M Jeong),박원조(W. J. Park),최병근(B. K. Choi),JunIchiro Tsubaki 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.11
Filtration is fundamental unit operation aimed at the separation of solids from the suspension by means of porous medium that retains the solids and allows the liquid to pass. Cake filtration is widely used in industry to separate solid particles from suspension in liquid. When the cakes are used as products in actual field, the solid-liquid separation has some problem such as high concentration cake, contamination of flocculants and batch type process of filtration. In this study, it has been developed the high performance cake-less filtration system whose condensed slurry layer maintains fluidity. The development of this novel filtration system allowed us to be unnecessary the scrapping operation of cake as well as to collect the high condensed slurry with more easily. These results clearly show that the new device will be realized for the making high condensed and fluidity slurry. It could be confirmed that the concentration of condensed slurry achieved 35 vol% with slurry fluidity. It is demonstrated that if particles are well dispersed, condensed slurry by filtration can be drained without scraper. In our new filtration system (DECAFF system), the specification of the system and operation conditions can be determined from a pre-filtration test.
김성수(S.S. Kim),박기태(G.T. Park),정한식(H.S. Chung),최희규(H.K. Choi) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.5
A simulation of the three-dimensional motion of grinding media in the stirred media mill for the research of grinding mechanism has been carried out by 3-dimensional Discrete Element Method (DEM). The power for the change of rotation speed of stirrer was examined based on the micro interactive forces at all the contact points between balls and between ball and stirrer. The results of DEM was compared with experimental measurements of power and showed similar power variation and force distribution which act on the stirrers of the mill. It could be also confirmed that DEM is a very powerful tool for the microanalysis of movement of balls, which has not been solved by conventional experimental method and for calculation of power of some mills which use balls as grinding media.