Services on Demand
Article
Indicators
Related links
-
Cited by Google
-
Similars in Google
Share
Journal of the Southern African Institute of Mining and Metallurgy
On-line version ISSN 2411-9717
Print version ISSN 2225-6253
J. S. Afr. Inst. Min. Metall. vol.110 n.11 Johannesburg Nov. 2010
JOURNAL PAPER
The potential of electrostatic separation in the upgrading of South African fine coal prior to utilization - a review
S.O. Bada; R.M.S. Falcon; L.M. Falcon
School of Chemical and Metallurgical Engineering, Faculty of Engineering and the Built Environment, University of the Witwatersrand, Johannesburg, South Africa
SYNOPSIS
Coal is a complex mixture of organic and mineral constituents and is the most abundant resource of fossil energy in the world. In recent years, significant research into dry coal beneficiation has gained much attention, primarily due to the need to improve grades and reduce the environmental contaminants in coal without the use of water, and to achieve this in as cost-effective manner as possible, relative to wet beneficiation processes. This paper seeks to review the application of various electrostatic separators with their process principles, to draw comparisons between different dry beneficiation techniques with specific emphasis on the triboelectrostatic separation method, and finally to report the results of triboelectrostatic separation conducted on various South African coals. Previous research conducted on Indian, European and American coals has indicated that this technique is likely to lead to significant economic benefit through the reduction of ash content, NOx and more specifically SOx by separating out the liberated Fe-S-bearing minerals prior to utilization. The removal of the latter suite of minerals is also likely to significantly reduce or eliminate the emissions of associated trace elements, including mercury and arsenic. The research results reported in this paper indicate that the rotary triboelectrostatic process has the potential for significant upgrading of high ash pulverized South African coal. The impact of various operational parameters was investigated and key factors established for the optimum recovery of low ash and low sulphur fine coal.
Keywords: Coal, dry beneficiation, electrostatic technique, rotary triboelectrostatic separator, high-gradient magnetic separation
“Full text available only in PDF format”
References
1. ALFANO, G., CARBINI, P., CICCU, R., GHIANI, R., and ZUCCA, A. Progress in Triboelectric Separation of Minerals, E. Forssberg (ed.), Proceedings of the XVI IMPC, Stockholm, Sweden. Amsterdam, 1988. pp. 833-844. [ Links ]
2. BADA, S.O., TAO, D., HONAKER, R.Q., FALCON, L.M., and FALCON, R.M.S. A Study of Rotary Tribo-Electrostatic Separation of South African Fine Coal. Proceedings of the XVI International Coal Preparation Congress, Lexington, Kentucky, USA, 2010. pp. 596-607. [ Links ]
3. BADA, S.O., TAO, D., HONAKER, R.Q., FALCON, L.M., and FALCON, R.M.S. Parametric study of electrostatic separation of South African fine coal. Mining Science and Technology, 2010. pp. 10-36. (Article in press). [ Links ]
4. BAN, H., SCHAEFER, J., and STENCEL, J. Size and velocity effects on coal particle triboelectrification and separation efficiency. Proceedings of International Pittsburgh Coal Conference, Pittsburgh. PA, 1993a. pp. 138-143. [ Links ]
5. BAN, H., YANG, J., SCHAEFER, J., SAITO, K., and STENCEL, J. Measurement of charge and charge distribution on coal and mineral matter during electrostatic dry coal cleaning. Proceedings of International Conference on Coal Science. Banf, AB, Canada, 1, 1993b. pp. 615-618. [ Links ]
6. BISWAL, S.K., DAS, S.P., REDDY, P.S.R., and MISRA, V.N. Prospect of beneficiation of high ash non-coking coals. Engineering Trends in Mineral Processing and Extractive Metallurgy, New Delhi, India, 2005. pp. 61-71. [ Links ]
7. BUDGE, G., BROUGH, J., KNIGHT, J., and BAKER PROCESS. Review of the Worldwide Status of Coal Preparation Technology, Report No. Coal R199 DTI/Pub URN00/1205. 23 pp., 2000. [ Links ]
8. BUTCHER, D.A. and ROWSON, N.A. Electrostatic separation of pyrite from coal. Magnetic and Electrical Separation, 1995. vol. 6, pp. 19-30. [ Links ]
9. CHENG, Q. and YANG, Y.F. Development of dry beneficiation of coal in China. Journal of Coal Preparation, 2003. vol. 23, pp. 3-12. [ Links ]
10. CHEN, Q. and WEI, L. Coal dry beneficiation technology in China: The state of the-art China. Particuology, 2003. vol. 1, no. 2, pp. 52-56. [ Links ]
11. CHOUNG, J., MAK, C., and XU, Z. Fine Coal Beneficiation using an Air Dense Medium Fluidized Bed. International Journal of Coal Preparation and utilization, 2006. vol. 26, no. 1, pp. 1-15. [ Links ]
12. DIEUDONNE, V., HEWITT, S., and WYK, D.N. Jigging the South-Africa coals-a new challenge. Mintek, Randburg, South Africa, 2001. [ Links ]
13. DWARI, R.K. and RAO, H.K. Tribo-electrostatic behaviour of high ash non coking Indian thermal coal. International Journal of Mineral Process, 2006. vol. 81, pp. 93-104. [ Links ]
14. DWARI, R.K. and RAO, H.K. Dry Beneficiation of coal-A review. Mineral Processing and Extractive Metallurgy, 2007. vol. 28, pp. 177-234. [ Links ]
15. DWARI, R.K. and RAO, H.K. Characterising Electron Transfer Mechanism in Tribo Electrification of pyrite through Contact Angle Measurements. The Open Mineral Processing Journal, 2008. vol. 1, pp. 6-17. [ Links ]
16. DWARI, R.K. and RAO, H.K. Non-coking coal preparation by novel triboelectrostatic method. Fuel, (Article in press), 2008. [ Links ]
17. DWARI, R.K. and RAO, H.K. Fine coal preparation using novel tribo-electrostatic separator. Minerals Engineering, 2009. vol. 22, no. 2, pp. 119-127. [ Links ]
18. DYRENFORTH, W.P. Electrostatic Separation, Mineral Processing Design. AIME. Muller and Bhappu (eds.), 2nd edn, 1978. pp. 479-489. [ Links ]
19. FINSETH, D., NEWBY, T., and ELSTRODT, R. Dry electrostatic separation of fine coal. Processing and Utilization of High Sulfur Coals, V.B.K. Parekh, and J.G. Groups, (eds.), Amsterdam, Elsevier, 1993. pp. 91-98. [ Links ]
20. GIDASPOW, D. Separation of pyrites from Illinois coals using electrofludized beds and electrostatic sieve conveyors. Proceedings of the Second International Conference on the Processing and Utilization of High Sulfur Coals II, Carbondale, IL. 1987. [ Links ]
21. GIDASPOW, D., GUPTA, R., MUKHERJEE, A., and WASAN, D. Separation of Pyrites from Illinois Coals Using Electro-fluidized Beds and Electrostatic Sieve Conveyors. Processing and Utilization of High Sulfur Coals II, Elsevier. 1987. [ Links ]
22. HAYAKAWA, S., SAKAGUCHI, E., and YAMASHITA, R. Conditions of Suited for separation of tea stems by electrostatic separator. Journal of Institution of Agriculture Machine, 1985. vol. 47, pp. 107-112. [ Links ]
23. HIGASHIYAMA, Y. and ASANO, K. Recent progress in electrostatic separation technology. Particulate science and technology, 1998. vol. 16, no. 1, pp. 77-90. [ Links ]
24. HOWER, J.C., HANG, B., SCHAEFER, J.L., and STENCEL, J.M. Maceral/microlithotype partitioning through triboelectrostatic dry coal cleaning. International Journal of Coal Geology, 1997. vol. 34, pp. 277-286. [ Links ]
25. INCULET, I.I., QUINGLEY, R.M., BERGOUGNOU, M.A., and BROWN, J.D. Electrostatic beneficiation of hat creek coal in the fluidized state. CIM Bulletin, 1980. vol. 73, pp. 51-61. [ Links ]
26. INCULET, I.I. Electrostatic Mineral Separation, England, UK: Research Study Press Ltd, 1984a. 153 pp. [ Links ]
27. KELLY, E.G. and SPOTTISWOOD, D.J. The theory of electrostatic separations: A review. Part I. Fundamentals. Minerals Engineering, 1989a. vol. 2, no. 1, pp. 33-46. [ Links ]
28. KNOLL, F.S. and TAYLOR, J.B. Advances in Electrostatic Separation. SME Preprint, 1984. pp. 84-71. [ Links ]
29. KWETUS, B.A. Contact electrification of coal and minerals. Journal of Electrostatics, 1994. vol. 32, pp. 271-276. [ Links ]
30. LEWOWSKI, T. Electrostatic desulphurisation of Polish steam coals. Coal Preparation, 1993. vol. 13, pp. 97-105. [ Links ]
31. LOCKHART, N.C. Dry Beneficiation of Coal- Review Paper. Powder Technology, 1984. vol. 40, pp. 17-42. [ Links ]
32. MASUDA, S., TARAGUCHI, M., TAKASHASHI, T., and HAGA, K. Electrostatic Beneficiation of Coal Using a Cyclone-Tribocharger. IEEE Transactions of Industry Applications, 1984. vol. 1A-19. [ Links ]
33. MAZUMDER, M.K., TENNAL, K.B. and LINDQUIST, D.A. Triboelectric separation of coal from mineral impurities. Proceedings of the Annual Meeting of the Electrostatic Society of America, Morgan Hill, CA, Laplacian, 1995. pp. 59-70. [ Links ]
34. MAZUMDER, M.K., SIMS, R.A., BIRIS, A.S., SRIRAMA, P.K., SAINI, D., YURTERI, C.U., TRIGWELL, S. DE, S., and SHARMA, R. Twenty-first century research needs in electrostatic processes applied to industry and medicine. Chemical Engineering Science, 2006. vol. 61, pp. 2192-2211. [ Links ]
35. MBENDI South Africa Coal Mining-Overview. 2004. www.mbendi.co.za/indy/ming/coal/af/sa/p0005.htm (Cited, 22 February 2008). [ Links ]
36. MOORE, A.D. Electrostatic and its application. Wisley Publisher, New York, 1973. [ Links ]
37. MUKAI, S., ISHIKAWA, T., SHIDA, Y., and WAKAMATSU, T. Study on the Electrostatic Concentration of low ash coal in corona discharge field. Society of Mining Engineers AIME Transaction, 1967. 238, 205 pp. [ Links ]
38. MUKHERJEE, A., GIDASPOW, D., and WASAN, D.T. Surface charge of Illinois coal and pyrites for dry electrostatic cleaning. American Chemical Society, Division of Fuel Chemistry, 1987. vol. 32, no. 1, pp. 395-407. [ Links ]
39. NIFUKU, M. Static electrification phenomena in pneumatic transportation of coal. Journal of Electrostatics, vol. 23, 1989. pp. 45-54. [ Links ]
40. OLOFINSKII, N.F. Electric corona separation of coal fines and certain minerals. Moscow. Translated by Israel Program for Scientific Translations, 1969. The potential of electrostatic separation in the upgrading of South African fine coal [ Links ]
41. RUCKDESCHEL, F.R. and HUNTER, L.P. Contact electrification between insulators: Phenomenological aspects. Journal of Applied Physics, 1975. vol. 46, no. 10, pp. 4416-4430. [ Links ]
42. SAMUILA, A., URS, A., IUGA, A., MORAR, R., AMAN, F., and DASCALESCU, L. Optimization of Corona Electrode Position in Roll-Type Electrostatic Separators. IEEE Transactions on Industry Applications, 2005. vol. 4, pp. 527-533. [ Links ]
43. SHARMA, R., TRIGWELL, S., SIMS, R.A., and MAZUMDER, M.K. Modification of electrostatic properties of polymer powders using atmospheric plasma reactor. Mittal, K.L. (ed.), Polymer Surface Modification: Relevance to Adhesion, 2004. vol. 3, VSP, AH Zeist, the Netherlands, pp. 25-37. [ Links ]
44. SOONG, Y., SCHOFFSTALL, M.R., and LINK, T.A. Triboelectrostatic beneficiation of fly ash. Fuel, 2001. vol. 80, pp. 879-884. [ Links ]
45. TAO, D., MAO-MING, F., and JIANG, X. Dry coal fly ash cleaning using rotary triboelectrostatic separator. Mining Science and Technology. 2009. vol. 19, pp. 0642-0647. [ Links ]
46. TAYLOR, J.B. Separation of granular materials. Conference record IEE Annual Meeting, 1988. vol. 23, pp. 1741-1759. [ Links ]
47. TRIGWELL, S. and MAZUMDER, K.M. Tribocharging in electrostatic beneficiation of coals: Effects of surface composition on work function as measured by X-ray photoelectron spectroscopy and ultraviolet photoelectron spectroscopy in air. Journal of Vacuum Science and Technology, 2001. vol. A, 19, no. 4, pp. 1454-1459. [ Links ]
48. TRIGWELL, S. Correlation between surface structure and tribocharging of powders. Doctoral dissertation, University of Arkansas at Little Rock, USA, 2003. [ Links ]
49. TRIGWELL, S., GRABLE, N., YURTERI, C.U., SHARMA, R., and MAZUMDER, M.K. Effects of surface properties on the tribocharging characteristics of polymer powder as applied to industrial processes. IEEE Transactions on Industry Applications, 2003a. vol. 39, no. 1, pp. 79-86. [ Links ]
50. TRIGWELL, S., TENNAL, K.B., MAZUMDER, M.K., and LINDQUIST, D.A. Precombustion cleaning of coal by triboelectric separation of minerals. Particulate Science and Technology, 2003b. vol. 21, no. 4, pp. 353-364. [ Links ]
51. WEITKÄMPER, L. and WOTRUBA, H. Recent development in the dry cleaning of coal. Proceedings of Mineral processing Technology, Bhubaneswar, India, Allied, 2004. pp. 539-546. [ Links ]
52. WOROBIEC, A., STEFANIAK, E.A., POTGIETER-VERMAAK, S., SAWLOWICZ, Z., SPOLNIKA, Z., and VAN GRIEKEN, R. Characterization of concentrates of heavy mineral sands by micro-Raman spectrometry and CC-SEM/EDX with HCA. Applied Geochemistry, 2007. vol. 22, pp. 2078-2085. [ Links ]
53. YONGZHI, L. Electrostatic separation study and practice of fine particles rutile. Proceeding, 1st International Conference. Modern Process Mineralogy and Mineral Processing, Beijing, 1992. pp. 385-390. [ Links ]
54. ZHOU, G. and BROWN, D. Coal surface conditioning for electrostatic separation. Canadian Journal of Chemical Engineering, 1988. vol. 66, pp. 858-863. [ Links ]