Method of recovering room-and-pillar coal pillar by using external replacement supports

Patent metadata

Field	Value
Publication number	US-11021954-B2
Application number	US-201916763426-A
Country	US
Kind code	B2
Filing date	Feb 22, 2019
Priority date	Sep 4, 2018
Publication date	Jun 1, 2021
Grant date	Jun 1, 2021

Abstract

A method of recovering a room-and-pillar coal pillar by using external replacement supports. In the recovery of a room-and-pillar coal pillar, a cement material wall is formed by performing pouring around a coal pillar having a width to height ratio of less than 0.6, by means of a single-pillar sack arrangement technique, such that a coal pillar resource may be mined while a wall made from a cement filling material supports an overlying stratum. After mining is complete, a coal pillar goaf region is filled with the cement filling material, and after the cement filling material solidifies and is stable, the single pillar can be recovered.

First claim

What is claimed is:

1. A method for recovering room-type coal pillars by replacing with external supports, comprising the following steps:
1) casting a cement filling material wall around a room-type coal pillar by hanging bags on a single prop, and reserving a gap in the cement filling material wall;
2) mining the internal room-type coal pillar through the gap in the cement filling material wall, under a condition of supporting the overlaying strata with the cement filling material wall;
3) plugging the gap in the cement filling material wall and filling a cement filling material into the goaf area surrounded by the cement filling material wall, after the mining of the room-type coal pillar is completed;
4) recovering the single prop after the cement filling material is solidified and stabilized.

2. The method for recovering room-type coal pillars by replacing with external supports according to claim 1 , wherein the width-to-height ratio of the room-type coal pillar is less than 0.6.

3. The method for recovering room-type coal pillars by replacing with external supports according to claim 1 , wherein in the step 1), a mechanical model for the stage in which the overlaying strata is supported solely by the cement filling material wall is established on the basis of the Winkler beam theory, to obtain the displacement and stress condition of the roof in the supporting stage by the cement filling material wall; and the theoretical casting width of the cement filling material wall is obtained according to a first strength theory of roof and a determination criterion for the ultimate strength of the cement filling material wall.

4. The method for recovering room-type coal pillars by replacing with external supports according to claim 1 , wherein the width of the cement filling material wall is calculated through the following procedures:
a. sectioning a half plane of the room-type coal pillar for analysis, setting the load of the overlaying strata on the roof as a uniformly distributed load q, the foundation coefficient of the cement filling material wall as k, the spacing between adjacent small room-type coal pillars as c, the width of the cement filling material wall as b, the width of the room-type coal pillar as a and the total width of the room-type coal pillars as 2a, and the differential equation of deflection curve for the segments of the roof in the analyzed area is as follows:

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Assignees

• Univ China Mining

Inventors

• Zhou Nan
• Liu Hengfeng
• Li Meng
• Wu Zhongya
• Zhang Jixiong

Classifications

• E21D15/483

  made of flexible containers, e.g. inflatable, with or without reinforcement, e.g. filled with water, backfilling material or the like (laggings making use of fluid cushions E21D11/157) · CPC title

• E21F15/02

  Supporting means, e.g. shuttering, for filling-up materials · CPC title

• E21C41/18 Primary

  for brown or hard coal · CPC title

• E21F15/04

  Stowing mats; Goaf wire netting; Partition walls · CPC title

• E21F15/00

  Methods or devices for placing filling-up materials in underground workings (dams E21F17/103 {; chocks made of flexible containers filled with backfilling material E21D15/483}) · CPC title