Research On Continuous Mining Methods And Rock Control Technology

In recent years, with extensive mining methods adopted on a large scale in coalmines in China, a large amount of residual coal pillar and of irregular blocks of coalresources was left after longwall mining. These coal resources exploitation dependsmostly on the continuous miner short-wall mechanized mining technology. Facingsuch problems as too many coal pillars leaving in the continuous miner short-wallmining technology, low recycling rates, and roof management difficulty (easy to causelarge top to flap and cave to form hurricanes which will pose a threat to personnel andequipment), this paper, taking Ulanmulun Coal Mine in Shendong Mining Camp as anexample and based on theoretical analysis, proposes optimized designs of continuousmining roadway section, the layout, size of coal columns, mining caving parameterand equipment supporting; puts forwards the continuous miners’ block miningtechnology; and carries out systemic research on motion laws of damaged rocks,roof controlling ways and the ventilation systems through numerical simulation,laboratory simulation and on-site mining pressure observation. The study will providea theoretical basis for continuous miner faces design, and will have some veryimportant value for safe and high efficiency mining of corner coal resources and makeprogress in coal mining technology. Main conclusions:(1) The Single-axle compression strength of Direct roof of Corner blockworkface is between33.07~34.25MPa; the single-axle compression strength of mainroof is between61.631~124.222MPa. After theoretical analysis, the continuousminers’ block mining method is proposed, with the work face divided into severalsmall blocks with branch entry and connection roadways. The branch entry is80-120m long, and5-6m wide; pillars between blocks are10m apart; pillars of every cutare03.-1.5m apart.(2) Numerical simulation analysis shows that the biggest vertical stress of theblock mining method should be in the pillars between every cut, concentrationcoefficient reaching2.25~2.7.The larger the gob area becomes, the higher the stressvalue will be. The analogy simulation tests show that at the beginning of block mining,the quantity of separation and displacement of the roof remains very small and it caneasily form a large unsupported roof. With the recovering space enlarging, the roofcan fully collapse.(3) Mining pressure observation shows that the stress increases faster and of ahigh valve in the protective pillar of the branch entry while increases slowly and of a low value from the center to outside. As the gob area enlarges, the stress of the pillarincreases; when the gob area seals, the edge of the protective pillar of the branch entryachieves plastic status while the stress in the center of the pillar goes up continuously.During the recovery period, the displacement of the remaining triangle area in theconnection roadway and the branch entry’s protective pillar intensifies; after the gobarea seals, the roof falling speeds up and moves fiercely.(4) This method cancels the pillars between cuts or pre-reserving small pillars,and supports the roof with4or more hydraulic walking crawlers. As a result, thismethod realizes the fully-caving management of the roof; improves the recovery ratioby at least20%; and forms a total ventilation system to assure the required airflow inevery air assumption place through the return airways on the boarder of the work faceand reasonable wind curtain and auxiliary fan etc.(5)The roof’s management and control can be realized through such integratedtechniques as pillar support, support topping and pressure-leaking explosion, that is,to pre-reserve pillars of different functions, to use several hydraulic walking crawlersto prop the roof, and to use reasonable pressure-leaking explosion techniques torealize roof pressure-leaking to ensure safe production in the workface.