Alkali Leaching of Indian Coal for Ash Reduction

Document Type : Research Article

Authors

1 Mechanical Engineering Department, Thapar Institute of Engineering and Technology, P. O. Box 147004 Patiala, Punjab, INDIA

2 Mechanical Engineering Department, National Institute of Technology, Jamshedpur, Jharkhand, INDIA

3 Mechanical Engineering Department, Chandigarh University, Gharuan, Punjab, INDIA

Abstract

Coal is a major source of energy. The available Indian coal quality is very poor having very high ash content and low calorific value. Indian coal generates a large quantity of ash as a by-product of combustion. The objectives of the present study were to reduce the ash content of coal to produce ultra-clean coal. The coal was treated with a dual chemical leaching process consisting of NaOH followed by HCl.During experiments, the concentration of NaOH was varied from 2.5 to 10 M with 1.4 N HCl. Effect of shaking speed and time was analysed at 0, 50, 100, 150 and 200 rpm and 1, 2, 3 and 4 hours respectively. After chemical leaching, the ash content was reduced from 35.33 to 0.98% in the ultra-clean coal. The concentration of alkali, shaking speed and time of duration were found as highly influencing parameters for the reduction of ash content in the coal. Moreover, the current study should result in a better option for the removal of ash content from low-rank Indian coals.

Keywords

Main Subjects


[1] Meshram P., Purohit B.K., Sinha M.K., Sahu S.K., Pandey B.D., Demineralization of Low Grade Coal - A Review, Renew. Sust. Energy Rev. (RSER), 41: 745-761 (2015).
[2] 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 Processes, Fuel. Process. Technol. (FPT), 92: 764-770 (2011).
[5] Duz M.Z., Saydut A., Erdogan S., Hamamci C., Removal of Sulfur and Ash from Coal Using Molten Caustic Leaching, A Case Study from Hazro Fields Turkey, Energ. Explor. Exploit. (EEE), 27(6): 391-400 (2009).
[6] Jorjani E., Chapi H.G., Khorami M.T., Ultra Clean Coal Production by Microwave Irradiation Pretreatment and Sequential Leaching with HF Followed by HNO3, Fuel Process. Technol. (FPT), 92: 1898-1904 (2011).
[7] Mukherjee S., Borthakur P.C., Effects of Alkali Treatment on Ash and Sulphur Removal from Assam Coal, Fuel Process. Technol. (FPT), 85: 93-101 (2003).
[8] Alam H.G., Moghaddam A.Z., Omidkhah M.R., The Influence of Process Parameters on Desulfurization of Mezino Coal by HNO3/HCl Leaching, Fuel Process. Technol. (FPT), 90: 1-7 (2009).
[9] Ehsani M. R., Desulphurization of Tabas coal using Chemcial Reagents, Iran. J. Chem. Chem. Eng. (IJCCE), 25(2): 59-66 (2006).
[10] Ehsani M. R., Eghbali F., Reduction of Sulphur and Ash from Tabas Coal by Froth Flotation, Iran. J. Chem. Chem. Eng. (IJCCE), 26(2): 35-40 (2007).
[11] Weng S.H., Mossbauer Analysis of the Microwave Desulfurization Process of Raw Coal, J. Appl. Phys. (JAP), 73: 4680–4692 (1993).
[12] Bolat E., Saglam S., Piskin S., Chemical Demineralization of a Turkish High Ash Bituminuous Coal, Fuel Process. Technol. (FPT), 57: 93–99 (1998).
[13] Ryberg M.W., Owsianiak M., Laurent A., Hauschild M.Z., Power Generation From Chemically Cleaned Coals: Do Environmental Benefits of Firing Cleaner Coal Outweigh Environmental Burden of Cleaning?, Energ.  Env. Sci.(EES), 8(8): 2435-2447 (2015).
[14] Steel K.M., Besida J., O’donnell T.A., Wood D.G., Production of Ultra Clean Coal Part I—Dissolution Behaviour of Mineral Matter in Black Coal toward Hydrochloric and Hydrofluoric Acids, Fuel Process. Technol. (FPT), 70: 171-192 (2001).
[15] Wang J., Tomita A., Removal of Mineral Matter from some Australian Coals by Ca(OH)2/HCl Leaching, Fuel. (F), 77:1747-1753 (1998).
[17] Abdollahy M., Moghaddam A.Z., Rami K., Desulfurization of Mezino Coal using Combination of Flotation and Leaching with Potassium Hydroxide/Methanol, Fuel. (F), 85: 1117-1124 (2006).
[18] Penica E.T., Camacho L.F., Herrera C.A., Martinez D., Effect of Complexing Agents in the Desulphurization of Coal by H2SO4 and H2O2 leaching, Miner. Eng. (ME), 29: 121-123 (2012).
[19] Samanta R.S., Mondal C., Separation of Mineral Matter from Indian Coal by using Solvents, Int. J. Res. Eng. Technol. (IJRET), 3(2): 349-357 (2014).
[20] Rehman F., Malik S. R., Khan A. M., Zafar M. S., Waqas S., Chemical Treatment of Coal by Alkali Leaching Process, Sci. Int. (SI), 27(6): 6137-6140 (2015).
[21] Wahab A., Nawaz S., Shahzad K., Akhtar J., Kanwal S., Munir S., Sheikh N., Desulfurization and Demineralization of Lakhra Coal by Molten Caustic Leaching, Energ. Source. A (RUEE), 37: 1219-1223 (2015).
[22] Kusakabe K., Orita M., Kato K., Morooka S., Kato Y., Kusunoki K., Simultaneous Desulphurization and emineralization of Coal, Fuel (F), 68: 396-399 (1989).
[23] Steel K.M., Wu Z., Demineralization of a UK Bituminous Coal using HF and Ferric Ions, Fuel (F), 86: 2194-2200 (2007).
[24] Sun T., Shen Y., Jia J., Novel Desulfurization Method of Sodium Borohydride Reduction for Coal Water Slurry, Energ. Fuel. (EF), 25: 2963-2967 (2011).