Abstract
An analysis of an iron-ore processing plant showed that its performance was affected by seasonal temperature variations, resulting in reduced grinding efficiency during the winter months. Laboratory and pilot plant studies were conducted to determine the cause of the observed loss of efficiency at lower temperatures. Two types of experiments were performed: drop tests and wet grinding tests. Drop testing was performed to determine the effect of brittleness and frozen pore water on the breakage characteristics of the ore. The wet grinding tests were divided into laboratory tumble tests and pilot-plant tests. The combined results of drop testing and wet grinding were used to make predictions on the performance of plant-scale autogenous grinding.
From the drop tests, it was determined that dry iron ore, basalt and sandstone did not change in brittleness over the temperature range studied (−25° to 25°C). However, when the rocks were water-saturated, the highly porous sandstone became considerably more fracture-resistant upon freezing, due to “grouting” of the pores and preexisting cracks by ice. This effect was not seen for either the iron ore or the basalt, because they were considerably less porous than the sandstone. Tumble tests on both laboratory and pilot scales showed that both the addition of fines to the test charge and a reduction in temperature caused a decrease in the amount of new fines produced. This reduced fines production was the result of increased slurry viscosity when either the fines content increased or the temperature decreased.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
ASTM, 1991, “Standard method of drop shatter test for coal, D440-86,” Annual book of ASTM standards, American Society for Testing and Materials, Vol. 5.05, p. 214.
Colorado School of Mines Research Institute, 1978, unpublished research report N80402.
Davis, H.E., Troxell, G.E., and Hauck, G.F.W., 1982, The Testing of Engineering Materials, 4th Ed., McGraw-Hill Publishing Company, New York.
Gross, J., and Zimmerley, S.R., 1930, “Crushing and grinding III: Relation of work input to surface produced in crushing quartz,” Transactions, AIME/SME, Vol. 87, pp. 35–50.
Hertzberg, R.W., 1976, Deformation and Fracture Mechanics of Engineering Materials, John Wiley and Sons, Inc., New York.
Hukki, R.T., 1975, “The principles of comminution: An analytical summary,” Eng. Min. J., Vol. 176, pp. 106–110.
Kawatra, S.K., and Eisele, T.C., 1992, “Influence of temperature on the energy efficiency of an industrial circuit processing iron ore,” Minerals and Metallurgical Processing, Vol. 8, no. 1, pp. 32–37.
Kawatra, S.K., Moffatt, S.A., Eisele, T.C., and DeLa’O, K.A., 1994, “The effects of freezing conditions on rock breakage,” Minerals and Metallurgical Processing, Vol. 11, No. 3, pp. 178–184.
Mellor, M., 1971, “Strength and Deformability of Rocks at Low Temperatures,” US Army Corps Cold Regions Research and Engineering Laboratory (CRREL), report 294, Hanover, New Hampshire.
Vitton, S., 1978, Michigan Technological University, M.S. Thesis.
Author information
Authors and Affiliations
Additional information
SME preprint 96–144, SME Annual Meeting, March 11–14, 1996, Denver, CO. M&MP paper 96–616. Discussion of this peer-reviewed and approved paper is invited and must be submitted, in duplicate, prior to May 31, 1997.
Rights and permissions
About this article
Cite this article
Shoop, K.J., Kawatra, S.K. Effect of rock breakage characteristics and fines/clay content on the autogenous grinding of iron ore. Mining, Metallurgy & Exploration 14, 14–21 (1997). https://doi.org/10.1007/BF03402746
Received:
Revised:
Published:
Issue Date:
DOI: https://doi.org/10.1007/BF03402746