Effective Utilization of Coal Processing Waste: Separation of Low Ash Clean Coal from Washery Rejects by Hydrothermal Treatment. (17th February 2022)

• Record Type: Journal Article
• Authors: Sriramoju, Santosh Kumar; Babu, Varahala; Dash, Pratik Swarup; Majumdar, Saptarshi; Shee, Debaprasad
• Is Part Of: Mineral processing and extractive metallurgy review. Volume 43:Number 2(2022)
• Page Start: 165
• Page End: 181
• Publication Date: 2022-02-17
• Subjects: Coal -- Flotation -- Rejects -- Waste -- Sustainability -- Hydrothermal extraction -- Density separation -- Humic substance; Ore-dressing -- Periodicals; Metallurgy -- Periodicals; 621
• DOI: 10.1080/08827508.2020.1833196
• Languages: English
• ISSNs: 0882-7508

Abstract

ABSTRACT: Handling and disposal of high volume of fine coal tailings is a biggest challenge for coal washeries. Separation of clean coal by density separation and flotation shows limited yields of 23–28% and 13–14% respectively. Chemical leaching process has a challenge with the formation of insoluble salts. The present investigation aimed to separate clean coal by a combination of chemical-physical separation technique, i.e. alkaline hydrothermal process followed by density separation. Hydrothermal extraction of humic substance causes dissociation of coal aggregated structure (Mineral-Maceral-Pore structure), thus improves the separation. Experiments performed as per design of experiments and reduced design of experiments, where 100 µ particle size, 50% (w/w) pulp density, 4.5% KOH (w/w), and 140°C reaction temperature found to be optimum, at which 16.2% ash clean coal at 40.7% yield and humic acid by-product at 18.3% yield were obtained. Use of swelling agent such as tetrahydrofuran shown negative impact on clean coal recovery. Material balance and cost data were presented to show the techno-commercial viability of this technology.