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Mineral transformation of Thar and Lakhra Coals: Enhancing GCV and BTU for Sustainable energy applications

Authors

  • Najeeb Anjum Soomro

    Department of Petroleum and Gas Engineering, Dawood University of Engineering & Technology, Karachi, Pakistan
    Author

  • Sun Xianda

    School of Petroleum Engineering, Northeast Petroleum University, 163318, Daqing, P.R. China
    Author

  • Dong Wanbai

    Daqing Oilfield Co., Ltd. Exploration Division, Daqing City, Daqing Oilfield
    Author

  • Darya Khan Bhutto

    Department of Petroleum and Gas Engineering, Dawood University of Engineering & Technology, Karachi, Pakistan
    Author

  • Tahmina Fatima Siddiqui

    Department of Petroleum and Gas Engineering, Dawood University of Engineering & Technology, Karachi, Pakistan
    Author

  • Najeebullah Lashari

    Universiti Teknologi PETRONAS, Bandar Seri Iskandar, Perak, Malaysia
    Author

  • Afroze Khatoon

    Department of Petroleum and Gas Engineering, Dawood University of Engineering & Technology, Karachi, Pakistan
    Author

  • Zhang Rui

    School of Petroleum Engineering, China University of Petroleum (East China), Qingdao, P.R. China
    Author

  • Yin Duo

    Daqing Oilfield Water and Environmental Protection Company, Equipment Technology training Company, Automatic Control Maintenance Department, P.R. China
    Author

DOI:

https://doi.org/10.22581/0830

Keywords:

Thar Coal, Lakhra Coal, Gross Calorific Value (GCV), Demineralisation, Matrix Stabilisation

Abstract

Low-rank coals from Pakistan’s Thar and Lakhra basins are vital indigenous energy deposits, but their utilisation is mostly restricted due to high intrinsic moisture, high ash-forming mineral concentration and low calorific yield. This work assesses a sophisticated multi-mechanism chemical conditioning package—integrating alkaline demineralisation with potassium hydroxide KOH, oxidative desulfurization with sodium hypochlorite NaClO, and inorganic cleat-sealing with calcium carbonate CaCO3 to improve the thermochemical characteristics and stabilise the structural matrix of the coals. Laboratory tests included proximate and ultimate analyses, X-ray diffraction (XRD) mineralogical phase tracking, water saturation dynamics and high-precision bomb calorimetry. The experimental results demonstrated essential fuel quality improvements in both coal deposits. The best improvement was obtained using Lakhra coal which included 77.80% dry ash free (daf) elemental carbon and a gross calorific value of 34,150 kJ/kg (14,683 BTU/lb) and is classified as high volatile bituminous fuel. The coal was improved to 71.20% carbon (daf) and 32,250 kJ/kg (13,865 BTU/lb) calorific output with 20.0% improvement on an as received basis. XRD diffractograms indicated that the hydrophilic kaolinite clays were extracted preferentially by KOH and the reactive iron sulphides by NaClO. The presence of an extra calcite peak at 2θ ≈ 29.40° was also indicative of the physical deposit and retention of micro-particulate CaCO3 which effectively sealed cleat holes, reduced matrix slaking and limited surplus fluid saturation to roughly 12%. The results show that chemical conditioning is a viable non-destructive approach to upgrade low-rank Pakistani lignites to greater efficiency lower slagging solid fuels for advanced power generation, industrial co-firing and clean coal applications.

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Published

2026-10-01

Issue

Vol. 45 No. 4 (2026): October Issue

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Copyright (c) 2026 Mehran University Research Journal of Engineering and Technology

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How to Cite

Mineral transformation of Thar and Lakhra Coals: Enhancing GCV and BTU for Sustainable energy applications. (2026). Mehran University Research Journal of Engineering and Technology, 45(4), 162-182. https://doi.org/10.22581/0830

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