ABSTRACT

In coal beneficiation, ash content is the main focus area as it plays a vital role in controlling the yield and quality of the washed clean coal. Indian sub-bituminous and bituminous coals are of low-grade with intrinsically distributed ash-bearing minerals, which makes it difficult to segregate the low ash coal. Different stages of crushing and grinding techniques have been used to produce the desired feed size of coal washeries, i.e., −13 mm. During blasting and crushing, cracks propagate through the weaker interfaces within the coal particles. Petrographic analysis suggests the formation of good amount of naturally liberated maceral-rich particles of −13 mm size at different stages. These particles generated at mine site and primary crusher are subjected to further crushing during subsequent stages of secondary and tertiary crushing, resulting in more fine generation and higher energy consumption. Hence, an attempt has been made to check the washability characteristics of coals at different stages of crushing and effect of prescreening of coarse (−13 + 0.5 mm) and fine (−0.5 mm) fraction on washability characteristics of coal and overall clean coal yield. It was observed that −13 mm particles generated at early stage of crushing show good washability characteristics compared to the crushed lump coal (+13 mm) for the separation of 17.8–18% ash clean coal; and hence, prescreening of −13 mm prior to tertiary crushing improves the process efficiency.

摘要

在选煤中，灰分含量是主要关注领域，因为它在控制洗精煤的产量和质量方面起着至关重要的作用。印度次烟煤和烟煤品位低，含灰矿物固有分布，难以分离低灰分煤。已经使用不同阶段的破碎和研磨技术来生产洗煤厂所需的进料尺寸，即-13 mm。在爆破和破碎过程中，裂缝通过煤颗粒内较弱的界面传播。岩相分析表明在不同阶段形成了大量的自然释放的富含微晶质的 -13 毫米大小的颗粒。这些在矿场和初级破碎机产生的颗粒在随后的二级和三级破碎阶段进行进一步破碎，导致更精细的发电和更高的能耗。因此，已尝试检查煤在不同破碎阶段的可洗性特征以及粗（-13 + 0.5 mm）和细（-0.5 mm）部分的预筛分对煤的可洗性特征和整体精煤产量的影响. 据观察，与破碎的块煤（+13 mm）相比，破碎初期产生的-13 mm颗粒表现出良好的可洗性，用于分离17.8-18%灰分的精煤；因此，在三次破碎之前进行-13 mm 的预筛分提高了工艺效率。5 mm) 对煤的可洗性特征和整体清洁煤产量的影响。据观察，与破碎的块煤（+13 mm）相比，破碎初期产生的-13 mm颗粒表现出良好的可洗性，用于分离17.8-18%灰分的精煤；因此，在三次破碎之前进行-13 mm 的预筛分提高了工艺效率。5 mm) 对煤的可洗性特征和整体清洁煤产量的影响。据观察，与破碎的块煤（+13 mm）相比，破碎初期产生的-13 mm颗粒表现出良好的可洗性，用于分离17.8-18%灰分的精煤；因此，在三次破碎之前进行-13 mm 的预筛分提高了工艺效率。