Characterization and washability of Pakistani bituminous coal from Punjab

ABSTRACT

Pre-combustion cleaning techniques are used to remove unwanted impurities and environmentally harmful constituents in coal. In this study, gross samples collected from seven zones of Punjab coalfield were separately subjected to sizing into coarse (+25 mm), intermediate (–25 + 1.168 mm), fine (–1.168 + 0.147 mm), and ultrafine (–0.147 mm) fractions. Proximate and ultimate components, forms of sulfur and gross calorific value of all size fractions and the composite sample of each zone coal were determined. Float-sink tests were conducted on coarse, intermediate and fine fractions. The results show that Punjab coal contains moisture, ash, volatile matter, and fixed carbon in the range of 2.28–4.61%, 34.13–51.59%, 26.72–34.25%, and 18.17–28.92%, respectively, belonging to high volatile bituminous B and C categories. The large proportion of mass lies in the intermediate size range for Chambel (63.10%), Dandot (60.27%), Trans-Indus (54.83%), Dalwal (52.20%), and Ara-Basharat (47.22%) coals whereas coarse particles constitute the major proportion of Padhrar (47.92%) and Jhelum (45.83%) coals. At 16% target ash content, the overall clean coal yield achievable for Jhelum, Ara-Basharat, Dandot, Dalwal, Padhrar, Chambel, and Trans-Indus zone coals were found as 16.32%, 20.76%, 37.20%, 48.59%, 46.29%, 70.43%, and 67.40% with sulfur contents of 2.89%, 2.80%, 2.90%, 3.57%, 4.28%, 3.89%, and 4.21%, respectively. The extent of coal cleaning was found higher for the Central Salt Range (Padhrar and Chambel zone) and Western Punjab (Trans-Indus zone) coals than the Eastern Salt Range (Jhelum, Ara-Basharat, Dandot and Dalwal zone) coals based on their degrees of washing and S-values. Padhrar coal exhibits the best washing characteristics as revealed by its highest S-value of 78.5.

KEYWORDS:

• Characterization
• float-sink
• washability
• Punjab coal
• coal cleaning
• degree of washing

Acknowledgments

The authors are very grateful to the office of Research, Innovation and Commercialization of University of Engineering and Technology, Lahore-Pakistan for providing funding and necessary facilities to conduct this research work.

Additional information

Notes on contributors

Muhammad Shahzad

Dr. Muhammad Shahzad has been actively involved in full-time mining, coal preparation, and mineral processing related teaching and research at the University of Engineering & Technology Lahore-Pakistan. His major area of research involves coal characterization, design, and optimization of coal and mineral processing plants, environmental effects of mining and processing of coal and minerals, and sustainable development of mineral and coal resources.

Zulfiqar Ali

Prof. Dr. Zulfiqar Ali is currently serving as chairman of the Mining Engineering Department, University of Engineering & Technology Lahore-Pakistan. He did his Ph.D. and Post-Doctoral studies from Virginia Polytechnic Institute & State University, USA. He is an expert in engineering design and applications of advanced mineral and coal processing equipment and techniques especially related to the fine processing of coal.