Oil Aggregated Behavior for Coal Recovery and Combustion Characteristics of Their Aggregates from Different Grade Coals

Oil Aggregated Behavior for Coal Recovery and Combustion Characteristics of Their Aggregates from Different Grade Coals

Q. WANG H. NIIDA C. LIU H. KUROKAWA A. SARKAR K. SEKIGUCHI K. SUGIYAMA 

Department of Environmental Science and Technology, Graduate School of Science and Engineering, Saitama University, Japan

Hachinohe National College of Technology, Japan

Page: 
692–704
|
DOI: 
https://doi.org/10.2495/SDP-V9-N5-692–704
Received: 
N/A
|
Accepted: 
N/A
|
Published: 
31 October 2014
| Citation

OPEN ACCESS

Abstract: 

Large amounts of waste fine coals are very difficult to be treated due to the presence of ash and inorganic sulphur compounds. In order to use waste fine coal efficiently, a retrieval technique is necessary for the recov-ery of combustible contents of coal from fine waste coals. Nowadays, a flotation process has been used for the treatment, but it is impractical for developing countries due to its higher costs. Therefore, oil agglomera-tion process has been used to deal with these problems. In this study, the factors affecting the coal cleaning efficiency of the oil agglomeration process were investigated with the element contents and chemical structure of three different grade coals. Chemical contents in three different grade coals were determined by proximate and ultimate analyses and the differences in chemical structure of carbonaceous contents of different grade coals were investigated by a Fourier transform-infrared spectrometry. In free coals or their mixed samples, the ratio of ash and carbonaceous contents were maintained to make it homogeneous. From the results of oil agglomeration experiments, it was concluded that the characteristics of agglomerate and the coal cleaning efficiency of oil agglomeration were not only influenced by the type of oils but also by the oxygen contents and the aromatic and aliphatic chemical structures in different grade coals. The oxygenic functional groups of carbonaceous contents in coal samples prevented oil from attaching the carbonaceous surface and form the bulky aggregate. This depressed the combustible matter recovery, but this was resolved by changing the oil types. Oxygen contents in oils such as vegetable oil played a role in bridging material to the oxygenic functional groups of carbonaceous contents in coal samples. Meanwhile, it was observed that aromatic functional groups in carbonaceous contents interacted badly with the aliphatic functional groups in oil due to the resonance inspection of delocalized π electrons. Comparatively carbonaceous contents consisting of more aliphatic series or graphite-reinforced structures were tended to form aggregates easily. Even when different types of coals were used in the oil agglomeration, it was possible to achieve a better efficiency by taking these factors into account. Moreover, by thermogravimetric-derivative thermogravimetric (TG-DTG) analyses, it was found that the combustion characteristics of carbonaceous contents were improved due to oil attachment.

Keywords: 

Aliphatic and aromatic contents, ash contents, combustion characteristics, Fourier transform-infrared spectrometry (FT-IR), hydrophobicity, oil agglomeration, TG-DTG, waste fine coal

  References

[1] World Energy Outlook 2007 – China’s Energy Prospects, ISBN: 978-92-64-02730-5, IEA.

[2] Valdes, A.F. & Garcia, B., On the utilization of waste vegetable oils (WVO) as agglomerants to recover coal from coal fines cleaning waste (CFCW). Fuel, 85, pp. 607–614, 2006.

[3] Alonso, M.I., Valdes, A.F., Martinez-Tarazona, R.M. & Garcia, B., Coal recovery from coal fines cleaning wastes by agglomeration with vegetable oils: effects of oil type and concentration. Fuel, 78, pp. 753–759, 1999. doi: http://dx.doi.org/10.1016/S0016-2361(98)00218-X

[4] Gurses, A., Doymus, K. & Bayrakceken, S., Selective oil agglomeration of brown coal: a systematic investigation of the design and process variables in the conditioning step. Fuel, 75, pp. 1175–1180, 1996. doi: http://dx.doi.org/10.1016/0016-2361(96)00077-4

[5] Wang, Q., Kashiwagi, N., Apaer, P., Chen, Q., Wang, Y. & Maezono, T., Study on coal recovery technology from waste fine Chinese coals by a vegetable oil agglomeration process. WIT Trans-actions on Ecology and the Environment, Vol. 142, The Sustainable World, ed. C.A. Brebbia, WIT Press: Southampton, pp. 331–342, 2010, ISSN 1743-3541, doi: 10.2495/SWS100311.

[6] Wang, Q., Kashiwagi, N., Apaer, P., Chen, Q., Wang, Y., Maezono, T. & Niida, D., Recovery of combustible matter from waste fine Chinese coals by a waste vegetable oil agglomerating process and its combustion characteristics. WIT Transactions on Ecology and the Environ-ment, Vol. 143, Energy and Sustainability III, eds. C.A. Brebbia, A.M. Marinov & C.A. Safta, WIT Press: Southampton, pp. 327–338, 2011, ISSN 1743-3541, doi: 10.2495/ESUS110281. doi: http://dx.doi.org/10.2495/ESUS110281

[7] Gurses, A., Doymus, K. & Bayrakceken, S., Evaluation of response of brown coal to selective oil agglomeration by zeta potential measurements of the agglomerates. Fuel, 76, pp. 1439–1444, 1997. doi: http://dx.doi.org/10.1016/S0016-2361(97)00121-X

[8] Krysyna, J. & Barend, C.J., Relating coal oxidation and hydrophobicity: a petrographic approach. Fuel, 75, pp. 1611–1616, 1996. doi: http://dx.doi.org/10.1016/S0016-2361(96)00154-8

[9] Wang, Q., Niida, N.H., Apar, P., Chen, Q., Gui, L., Qian, Q., Mitsumura, N., Endou, T., Animesh, S. & Kurokawa, H., Clarification of the reaction at the solution interface of pyrite during oil agglomeration for developing desulfurization and coal cleaning efficiency. WIT Trans-actions on Ecology and the Environment, Vol. 176, Energy and Sustainability IV, ed. C.A. Breb-bia, WIT Press: Southampton, pp. 303–313, 2013, ISSN 1743-3541, doi: 10.2495/ESUS130261. doi: http://dx.doi.org/10.2495/ESUS130261

[10] Strydom, C.A., Bunt, J.R., Schobert, H.H. & Raghoo, M., Changes to the organic functional groups of an inertinite rich medium rank bituminous coal during acid treatment pro-cesses. Fuel Processing Technology, 92, pp. 764–770, 2011. doi: http://dx.doi.org/10.1016/j. fuproc.2010.09.008

[11] Geng, W., Nakajima, T., Takanashi, H. & Ohki, A., Analysis of carboxyl group in coal and coal aromaticity by Fourier transform infrared (FT-IR) spectrometry. Fuel, 88, pp. 139–144, 2009. doi: http://dx.doi.org/10.1016/j.fuel.2008.07.027

[12] Ozkan, A., Ucbetiay, H. & Duzyol, S., Comparison of stages in oil agglomeration process of quartz with sodium oleate in the presence Ca and Mg ions. Journal of Colloid and Interface Science, 329, pp. 81–88, 2009. doi: http://dx.doi.org/10.1016/j.jcis.2008.09.073

[13] Das, D., Dash, U., Nayk, A. & Misra, P.K., Surface engineering of low rank Indian coals by starch – based additives for the formulation of concentrated coal – water slurry. Energy Fuels, 24, pp. 1260–1268, 2010. doi: http://dx.doi.org/10.1021/ef900921c

[14] Niu, S., Han, K. & Lu, C., Release of sulfur dioxide and nitric oxide and characteristic of coal combustion under the effect of calcium based organic compounds. Chemical Engineering Journal, 168, pp. 255–261, 2011. doi: http://dx.doi.org/10.1016/j.cej.2010.10.082