Assessment of the Current Status of Mine Opening and Subdivision of Coal Reserves at the Synclinal Bottom

Hoang Hung Thang

Abstract: Mining coal reserves at synclinal bottoms is one of the most technically challenging operations in underground coal mining due to unfavorable geological structures, complex hydrogeological conditions, and high risks of coal loss. In the underground coal mines of Quang Ninh Province, Viet Nam, many mines are currently approaching or entering the synclinal bottoms of multiple coal seams as shallow reserves become depleted. This paper presents a comprehensive assessment of the current status of mine opening schemes and coal reserve subdivision at synclinal bottoms, based on detailed case studies of the Nam Mau and Nam Khe Tam underground coal mines. The study analyzes applied mine opening methods, roadway layouts, subdivision of mining blocks, and associated advantages and limitations. The results show that two-level opening systems combining crosscut roadways and rock rises provide superior conditions for ventilation and natural drainage, thereby improving safety during synclinal bottom mining. However, this approach is associated with increased rock drivage and potential coal losses in thick seams. Single-level opening by downward roadways reduces development costs but leads to high drainage and ventilation complexity. The findings provide a scientific basis for optimizing mine opening and coal reserve subdivision strategies for synclinal bottom mining in Vietnamese underground coal mines.

Keywords: Synclinal bottom, mine opening, coal reserve subdivision, underground coal mining, Quang Ninh Province