Improvement of bulk density of coal charge by using surface active reagent Debjani Nag, Susmit M. Nimje, Soumen Maji, Soumik Roy, P.S. Dash and Mantu Patra Metall. Res. Technol., 121 4 (2024) 410 Published online: 28 June 2024 DOI: 10.1051/metal/2024047