Optimizing the Characteristics of the Motion of Steel Balls and their Impact on Shell Liners in SAG Mills

Document Type : Research Paper

Authors

1 Faculty of Mechanical Engineering, Khajeh Nasir-Addin Toosi University of Technology

2 Mechanical Engineering Department,Shahid-Bahonar University of Kerman

Abstract

The equations governing the motion of steel balls and their impact onto shell liners in industrial Semi-Autogenous Grinding (SAG) mills are derived in full details by the authors and are used in order to determine the effective design variables for optimizing the working conditions of the mill and to avoid severe impacts which lead to the breakage of SAG mill shell liners. These design variables are the lifter height H, the working coefficient of friction µ, lifter face inclination angle φ, steel ball size rB, mill rotational velocity ω, and mill size R. In order to optimize the operating conditions and avoid severe impacts to its shell liners, the effect of these parameters need to be studied. The effect of lifter height (H) and the coefficient of friction (μ) on some of the main impact characteristics are simultaneously investigated for a SAG mill in Sarcheshmeh Copper Complex. It was shown that as the lifter height or the coefficient of friction increases, the impact position tends to move upward, but the maximum impact force and the absolute value of the maximum principal stress decreases, reducing the impact severity.

Keywords


[1] Delboni, H. Jr., and Morrell, S., “A Load-interactive Model for Predicting the
Performance of Autogenous and Semi-Autogenous Mills”, KONA, Vol. 20, pp. 208-
222, (2002).
[2] Grant, E., and Kalman, H., “Experimental Analysis of the Performance of an Impact
Mill”, Advanced Powder Technology, Vol. 13, No. 3, pp. 233–247, (2002).
[3] Rajamani, R. K., Mishra, B. K., Latchireddi, S., Patra, T. N., and Prathy, S. K., On the
Dynamics of Charge Motion in Grinding Mills, Proceedings of the Jan. D. Miller
Symposium (SME Annual meeting), Salt Lake City, USA, Feb. (2005).
[4] Cleary, P. W., “Recent Advances in DEM Modeling of Tumbling Mills”, Minerals
Engineering, Vol. 14, No. 10, pp. 1295-1319, (2001).
[5] Djordjevic, N., Shi, F. N., and Morrison, R., “Determination of Lifter Design, Speed and
Filling Effects in AG Mills by 3D DEM” Minerals Engineering, Vol. 17, No. 11-12, pp.
1135-1142, (2004).
[6] Svedala Canada, “Data Sheets for 32×16 ft SAG Mill”, Sarcheshmeh Copper Mining
Company, Rafsanjan, Iran, (2001).
[7] Carson, G., and Mulholland, A. J., “Particle Sizing using Hertz-zener Impact Theory and
Acoustic Emission Spectra” Research Report No. 15, Department of Mathematics,
University of Strathclyde, Glasgow, UK, Sept. (2005).
[8] Boresi, A. P., and Schmidt, R. J., “Advanced Mechanics of Materials”, 6th Edition, John
Wiley and Sons, New Jersey, (2003).
[9] Whittaker, E. T., and Watson, G. N., “A Course in Modern Analysis”, 4th Edition,
Cambridge University Press, Cambridge, (1990).
[10] Weisstein, E. W., “Beta Function”, MathWorld- A Wolfram Web Resource (2007).
http://mathworld.wolfram.com/BetaFunction.html
[11] Meriam, J. L., and Kraige, L. G., “Engineering Mechanics: Dynamics”, 6th Edition,
John Wiley and Sons, New Jersey, (2007).
[12] Ebrahimi-Nejad, Salman, “Analysis of the Dynamics of SAG Mill Contents and the
Liner Behavior Due to Impact”, MSc Thesis, Mechanical Engineering Department,
Shahid-Bahonar University, Kerman, (2007).