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ArticleName Microwave treatment of rocks: effect on specific gravity, whiteness, and grindability
DOI 10.17580/or.2020.03.02
ArticleAuthor Sefiu O. A., Hussin A. M. A., Haitham M. A. A.

King Abdulaziz University, Jeddah, Kingdom of Saudi Arabia:

Sefiu O. A., PhD candidate, (corresponding author)

Hussin A. M. A., Professor, Dr. Eng.

Haitham M. A. A., Assistant Professor, PhD PMP


Heating of ores usually improves the liberation of minerals and reduces grinding energy consumption. One of the heating methods is using microwave electromagnetic radiation, which may change the rock’s physical properties. This paper investigates the effect of microwave heating of rocks on their physical properties. The physical properties monitored were specific gravity, whiteness, and grindability due to their importance for the downstream processes. Two rock types were investigated: coral as the soft rock and quartzite as the hard rock. The rock samples tested were treated for different time intervals in a microwave oven (frequency — 2.45 GHz, P = 1.7 kW). The results showed that specific gravity of the soft rock decreased by 1.82 % after the microwave treatment (150 s), while that of the hard rock was not affected. It was also found that the maximum change in rock whiteness for the soft rock is 8.65 % after the microwave treatment (150 s), while that of the hard rock was 6.02 % after a 120 s microwave radiation exposure period. Following a 60 s microwave radiation exposure, the soft rock demonstrated the work index of 20.99 % against the value of 45.03 % of the hard rock. The results of FTIR and XRD analyses suggest that changes in the physical property and a phase shift of minerals may be responsible for the improvement in the work index and whiteness of the rocks studied.

This project was funded by the Deanship of Scientific Research (DSR), King Abdulaziz University, Jeddah. The authors are very grateful to the DSR for their technical and financial support.

keywords Comminution, grinding, crushing, liberation, work index, energy, ore treatment

1. Reyes F., Lin Q., Cilliers J. J., Neethling S. J. Quantifying mineral liberation by particle grade and surface exposure using X-ray microCT. Minerals Engineering. 2018. Vol. 125. pp. 75–82.
2. Bond F. C. Crushing and grinding calculations. Part I. British Chemical Engineering. 1961. Vol. 6, No. 6. pp. 378–385.
3. Hussin A. M. A., El-Midany A. A. Correlation between phosphate ore Bond Work Index (Wi) and its chemical composition. Obogashchenie Rud. 2019. No. 1. pp. 12–17.
4. Curry J. A., Ismay M. J. L., Jameson G. J. Mine operating costs and the potential impacts of energy and grinding. Minerals Engineering. 2014. Vol. 56. pp. 70–80.
5. Omran M., Fabritius T., El-Mahdy A. F. M., Abdel-Khalek N. A. Improvement of phosphorus removal from iron ore using combined microwave pretreatment and ultrasonic treatment. Separation and Purification Technology. 2015. Vol. 156. pp. 724–737.
6. Wang E., Shi F., Manlapig E. Mineral liberation by high voltage pulses and conventional comminution with same specific energy levels. Minerals Engineering. 2012. Vol. 27–28. pp. 28–36.
7. Yu J., Han Y.-X., Li Y.-J., Gao P. Effect of magnetic pulse pretreatment on grindability of a magnetite ore and its implication on magnetic separation. Journal of Central South University. 2016. Vol. 23. pp. 3108–3114.
8. Swart A. J., Mendonidis P. Evaluating the effect of radio-frequency pre-treatment on granite rock samples for comminution purposes. International Journal of Mineral Processing. 2013. Vol. 120. pp. 1–7.
9. Choi H., Lee W., Kim D. U., Kumar S., Kim S. S., Chung H. S., Kim J. H., Ahn Y. C. Effect of grinding aids on the grinding energy consumed during grinding of calcite in a stirred ball mill. Minerals Engineering. 2010. Vol. 23. pp. 54–57.
10. Genç Ö., Benzer A. H. Effect of High Pressure Grinding Rolls (HPGR) pre-grinding and ball mill intermediate diaphragm grate design on grinding capacity of an industrial scale two-compartment cement ball mill classification circuit. Minerals Engineering. 2016. Vol. 92. pp. 47–56.
11. Wills B. A., Napier-Munn T. Mineral processing technology. An introduction to the practical aspects of ore treatment and mineral recovery. 7 ed. Elsevier Science & Technology Books, 2006. 450 p.
12. van Oss H. G. 2016 Minerals yearbook. Cement [Advance release]. U. S. Geological Survey, 2020, January. 34 p.
13. Bobicki E. R., Liu Q., Xu Z. Microwave treatment of ultramafic nickel ores: Heating behavior, mineralogy, and comminution effects. Minerals. 2018. Vol. 8. Paper 524.

14. Berry T. F., Bruce R. W. A simple method of determining the grindability of ores. Canadian Mining Journal. 1966. Vol. 87. pp. 63–65.
15. Vaculíková L., Plevová E. Identification of clay minerals and micas in sedimentary rocks. Acta Geodynamica et Geomaterialia. 2005. Vol. 2, No. 2. pp. 167–175.
16. Konecny P., Hagib A., Plevova E., Vaculikova L., Murzyn T. Characterization of limestone from cement plant at Berbera (Republic of Somaliland). Procedia Engineering. 2017. Vol. 191. pp. 43–50.
17. Reig F. B., Adelantado J. V. G., Moya Moreno M. C. M. FTIR quantitative analysis of calcium carbonate (calcite) and silica (quartz) mixtures using the constant ratio method. Application to geological samples. Talanta. 2002. Vol. 58, No. 4. pp. 811–821.
18. Nila A. S. S., Radha K. P. Synthesis and XRD, FTIR studies of alumina nanoparticle using co-precipitation method. International Journal for Research in Applied Science & Engineering Technology. 2018. Vol. 6, Iss. III. pp. 2493–2496.
19. Zaini N. Infrared carbonate rock chemistry characterization: dissertation. Enschede: University of Twente, 2018. 129 p.

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