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.

摘要

处理和处置大量细煤尾矿是洗煤厂面临的最大挑战。通过密度分离和浮选分离精煤的产量有限，分别为 23-28% 和 13-14%。化学浸出过程具有形成不溶性盐的挑战。本研究旨在通过化学-物理分离技术相结合的方法分离精煤，即碱性水热工艺，然后进行密度分离。腐殖质的水热提取导致煤聚集结构（矿物-微晶-孔结构）的解离，从而提高了分离度。根据实验设计和简化的实验设计进行实验，其中 100 µ 粒径、50% (w/w) 纸浆密度、4.5% KOH (w/w) 和 140°C 反应温度是最佳的，在其中 16. 得到2%灰分精煤，收率40.7%，腐殖酸副产物收率18.3%。使用四氢呋喃等膨胀剂对精煤回收有负面影响。提供了材料平衡和成本数据，以显示该技术的技术商业可行性。