Slicing mining of thick gently dipping coal in China: Problems and improvement

In underhand mining with slicing of thick seams with safety patches left between slices, the operation in longwalls of an underhand (lower-lying) level features high coal losses and increased hazard. The high hazard of mining using the known technology is connected with collapse of the inter-slice safety patches in the lower layer longwalls as well as with much overground and inflammable coal left in mined-out space. The article reviews the collapse causes of an inter-slice coal patch and rocks in the face area of longwalls on the lower lying layer as a case-study of promising Hang Laivan Mine in Shanxi. It is found that an essential impact is exerted on the stability of the safety patch of coal by the rate of its damage under the action of the abutment pressure generated in front of the longwall on the upper lying layer. In Hang Laivan Mine, the depth of softening in the underhand-cut coal at the stage of the main roof caving is to 0.35 m and more. The inter-slice safety patch of coal nearby the mined-out area of the upper layer longwall is, as a rule, fractured and almost unstable. This fact should be included in design of the minimal thickness of the inter-slice safety patches of coal. The promising trends in improvement of the slicing technology for thick (8–12 m) and gently dipping coal seams are identified. A safe and resource-saving technology is proposed for underhand mining of inclined layers. The technology allows total elimination of coal losses in the inter-slice safety patches and enhances safety of mining.

Zubov V. P., Li Yunpeng, Slicing mining of thick gently dipping coal in China: Problems and improvement. MIAB. Mining Inf. Anal. Bull. 2023;(7):37-51. [In Russ]. DOI: 10.25018/0236_1493_2023_7_0_37.

V.P. Zubov¹, Dr. Sci. (Eng.), Professor, e-mail: spggi.zubov@mail.ru,
Li Yunpeng¹, Graduate Student, e-mail: yunpengli@mail.ru, ORCID ID: 0000-0003-2677-2757,
¹ Saint-Petersburg Mining University, 199106, Saint-Petersburg, Russia.

V.P. Zubov, e-mail: spggi.zubov@mail.ru.

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