TRANSACTION PAPERS

 

The effect of feed-coal particle size on the separating characteristics of a gas-solid fluidized bed

 

 

Y.M. Zhao; Z.F. Luo; Z.Q. Chen; L.G. Tang; H.F. Wang; H.B. Xing

School of Chemical Engineering and Technology, China University of Mining and Technology, Xuzhou, China

 

 

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SYNOPSIS

The separating performance of a pilot dry beneficiation system using a gas-solid fluidized bed was investigated with coal from South Africa. The coal used for the study has a low inherent moisture content, a moderate ash content, a moderate volatile content, a low sulphur content and a high calorific value. Its washability is moderate. Experimental results show that the separating quality of the fluidized bed drops gradually as the feedcoal particle size decreases. The probable error, E, values for 50-25 mm, 25-13 mm and 13-6 mm coals were 0.04 g/cm³, 0.06 g/cm³ and 0.09 g/cm³, respectively. The cause of the differences in separating characteristics was analysed by particle dynamics and numerical modelling. Furthermore, the pilot fluidized bed was employed to separate 50-6mm coal. In this experiment the coal ash content was reduced from 23.74% to 11.79%, with a probable error, E, value of 0.07 g/cm³ and a recovery efficiency of 98.26%. This indicates that the fluidized bed is applicable to the separation of coal from South Africa and has good separating performance and wide applicability.

Keywords: feed-coal particle size; gas-solid fluidized bed; dry coal beneficiation; numerical simulation

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References

1. DWARI, R.K. and RAO, K.H. Dry beneficiation of coal-a review. Mineral Processing and Extractive Metallurgy Review, vol. 28, no. 3, 2007. pp. 177-234.         [ Links ]

2. VAN HOUWELINGEN, J.A. and DE JONG, T.P.R. Dry Cleaning of Coal: Review, Fundamentals and Opportunities. Proceedings of the 5th European Coal Conference. Geologica Belgica, 2004. vol. 7, pp. 335-343.         [ Links ]

3. KUNII, D. and LEVENSPIEL, O. Fluidization Engineering. Boston, Butterworth -Heinemann, 1991.         [ Links ]

4. FRASER, T. and YANCEY, H.F. The air-sand process of cleaning coal. US Pat 153, 4846: Acc. 21 April 1925.         [ Links ]

5. CHAPMAN, W.R. and MOTT, R.A. The Cleaning of Coal. London, Chapman & Hall Ltd., 1928.         [ Links ]

6. BEECKMANS, J.M. Separation of Mixed Granular Solids Using the Fluidized Counter Current Cascade Principle. The Canada Journal of Chemical Engineering, vol. 75, no. 10, 1997. p. 55.         [ Links ]

7. CHAN, E.W. and BEECKMANS, J.M. Pneumatic beneficiation of coal fines using the counter-current fluidized cascade. International Journal of Mineral Processing, vol. 9, no. 2, 1982. pp. 157-165.         [ Links ]

8. DONG, X. and BEECKMANS, J.M. Separation of Particulate Solids in a Pneumatically Driven Counter-current Fluidized Cascade, Powder Technology, vol. 62, no. 3, 1990. pp. 261-267.         [ Links ]

9. OSHITANI, J., TANI, K., TAKASE, K., and TANAKA, Z. Dry Coal Cleaning by Utilizing Fluidized Bed Medium Separation (FBMS). Proceedings of the SCEJ Symposium on Fluidization. Japan, 2003. vol. 9, pp. 425-430.         [ Links ]

10. TANAKA, Z., OSHITANI, J., KUBO, Y., and ZUSHI, T. Dry Coal Cleaning in Drewboy Bath Type by Dry Heavy Medium. Proceedings of First International Symposium on Dry Coal Cleaning, Clean Coal Technology. Chen, Q. R. and Tanaka, Z. (eds.). Xuzhou. China University of Mining and Technology Press, 2002. pp. 73-78.         [ Links ]

11. KUBO, Y. and ZUSHI, T. Designing Points of the Fluidized Bed Type Dry Coal Cleaning System. Proceedings of First International Symposium on Dry Coal Cleaning, Clean Coal Technology. Chen, Q. R. and Tanaka, Z. (eds.). Xuzhou. China University of Mining and Technology Press, 2002. pp. 79-89.         [ Links ]

12. TANAKA, Z., SATO, H., KAWAI, M., OKADA, K., and TAKAHASHI, T. Dry Coal Cleaning Process for High-quality Coal. Journal of chemical engineering of Japan, vol. 29, no. 2, 1996. pp. 257-263.         [ Links ]

13. LUO, Z.F., ZHU, J.F., LI, Z., and LIU, K.L. Surface Modification of Hydrophobic Magnetite Powder. Journal of China University of Mining & Technology, vol. 38, no. 1, 2009. pp. 75-79. (in Chinese)        [ Links ]

14. LUO, Z.F., ZHU, J.F., FAN, M.M., ZHAO, Y.M., and TAO, X.X. Low Density Dry Coal Beneficiation Using an Air Dense Medium Fluidized Bed. Journal of China University of Mining and Technology, vol. 17, no. 3, 2007. pp. 0306-0309.         [ Links ]

15. LUO, Z., ZHAO, Y., FAN, M., TAO, X., and CHEN, Q. Density Calculation of a Compound Medium Solids Fluidized Bed for Coal Separation. The Journal of The Southern African Institute of Mining and Metallurgy, vol. 106, no. 11, 2006. pp. 749-752.         [ Links ]

16. LUO, Z.F., ZHAO, Y.M., CHEN, Q.R., TAO, X. X., and FAN, M.M. Effect of Gas Distributor on Performance of Dense Phase High Density Fluidized Bed for Separation. International Journal of Mineral Processing, vol. 74, nos. 1-4, 2004. pp. 337-341.         [ Links ]

17. LUO, Z.F., ZHAO, Y.M., TAO, X.X., FAN, M.M., CHEN, Q.R., and WEI, L.B. Progress in Dry Coal Cleaning Using Air-dense Medium Fluidized Beds. Coal Preparation, vol. 23, nos. 1-2, 2003. pp. 13-20.         [ Links ]

18. LUO, Z.F., CHEN, Q.R., and ZHAO, Y.M. Dry Beneficiation of Coarse Coal Using an Air Dense Medium Fluidized Bed (ADMFB). Coal Preparation, vol. 22, no. 1, 2002. pp. 57-64.         [ Links ]

19. LUO, Z.F. and CHEN, Q.R. Effect of Fine Coal Accumulation on Dense Phase Fluidized Bed Performance. International Journal of Mineral Processing, vol. 63, no. 4, 2001. pp. 217-224.         [ Links ]

20. LUO, Z.F. and CHEN, Q.R. Dry Beneficiation Technology of Coal with an Air Dense-medium Fluidized Bed. International Journal of Mineral Processing, vol. 63, no. 3, 2001. pp. 167-175.         [ Links ]

21. LUO, Z.F., FAN, M.M., ZHAO, Y.M., TAO, X.X., CHEN, Q.R., and CHEN, Z.Q. Density-dependent Separation of Dry Fine Coal in a Vibrated Fluidized Bed. Powder Technology, vol. 187, no. 2, 2008. pp. 119-123.         [ Links ]

22. LUO, Z.F., FAN, M.M., ZHAO, Y.M., TAO, X.X., and CHEN, Z.Q. Separation of Material in a Vibration Fluidized Bed. Journal of China University of Mining &Technology, vol. 36, no. 1, 2007. pp. 27-32. (in Chinese)        [ Links ]

23. LUO, Z.F., FAN, M.M., CHEN, Q.R., ZHAO, Y.M., LIANG, C.C., TAO, X.X., and CHEN, Z.Q. Effects of Vibrating Parameters on Separation Performance of Fluidized Beds. Journal of China University of Mining & Technology, vol. 35, no. 2, 2006. pp. 209-213. (in Chinese)        [ Links ]

24. LUO, Z.F., ZHAO, Y.M., CHEN, Q.R., TAO, X.X., and FAN, M.M. Separation Lower Limit in a Magnetically Gas-solid Two-phase Fluidized Bed. Fuel Processing Technology, vol. 85, nos. 2-3, 2004. pp. 173-178.         [ Links ]

25. FAN, M.M., CHEN, Q.R., and ZHAO, Y.M. Fundamentals of a Magnetically Stabilized Fluidized Bed for Coal Separation. Coal Preparation, vol. 23, nos. 1-2, 2003. pp. 47-55.         [ Links ]

26. LUO, Z.F., ZHAO, Y.M., CHEN, Q.R., FAN, M.M., and TAO, X.X. Separation Characteristics for Fine Coal of the Magnetically Fluidized Bed. Fuel Processing Technology, vol. 79, no. 1, 2002. pp. 63-69.         [ Links ]

27. WANG, J.H., CHEN, Q.R., KUANG, Y.L., LYNCH, A.J., and ZHUO, J.W. Grinding Process Within Vertical Roller Mills: Experiment and Simulation, Mining Science and Technology, vol. 19, no. 1, 2009. pp. 97-101.         [ Links ]

28. WANG, Y.L., ZHAO, Y.M., and YANG, J.G. Research on Super-low-ash Anthracite Preparation. Journal of China University of Mining & Technology, vol. 18, no. 4, 2008. pp. 0580-0583.         [ Links ]

29. CAI, S.T. The mechanical property of the slurry and the resistance force of a sphere moving with uniform velocity in the slurry. Applied Mathematics and Mechanics, vol. 2, 1981. pp. 267-272. (in Chinese)        [ Links ]

30. WEI, L.B., BIAN, B.X., CHEN, Q.R., and ZHAO, Y.M. Study on terminal velocity of objects moving in fluidized beds. Journal of China University of Mining & Technology, vol. 30, no. 1, 2001. pp. 5-8. (in Chinese).         [ Links ]

 

 

Paper received Jul. 2009
Revised paper received Dec. 2009