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·The overall matching pattern for the parallel and balanced shear and caving in coal face and complete sets of technical system for the fully mechanized top coal caving mining used to extract ultra thick seams with shear height of 5 m or more; the invention of a three dimensional 3D dynamic optimized design method for coupling hydraulic
·The top coal caving of No 6 coal seam was systematically evaluated with statistical results of coal seam recovery height h re and mining caving ratio R mc an indicator for the division of LLTCC feasible regions in the Laosangou mining field which is based on the R mc h re coal wall stability and equipment selection The results
·1 Introduction The longwall top coal caving LTCC is the main method to extract thick and extrathick coal seams Figure 1 shows the basic procedure of LTCC A longwall fully mechanized mining is arranged at the bottom coal seam where the coal is cut by the shearer with transporting out of the panel by the front scraper conveyor
Longwall top coal caving LTCC techniques has been employed in favourable geological conditions widely in China since the mid 80s and in Australia recently With the improvement of highly powered face equipment and the method itself in the past 15 years LTCC was introduced to more challenging geological conditions such as unfavourable roof conditions complex
·With the development of the technology and equipment of large mining height and fully mechanized top coal caving the organic combination of large mining height and fully mechanized top coal caving has formed the unique mining method of 8 15 m coal seam mining which has become an important technical approach to realize the safe high yield and efficient
·The coal gangue boundary curve at different times a The boundary curve at 20° b The boundary curve at 22° c The boundary curve at 24°
Thick and ultra thick coal seams are main coal seams for high production rate and high efficiency in Chinese coal mines which accounts for 44 % of the total minable coal reserve A fully mechanized top coal caving mining method is a main underground coal extraction method for ultra thick coal seams The coal extraction technologies for coal seams less than 14 m thick
·Top coal caving is a process for the rational extraction of large amounts of coal resources However this process readily causes release of excessive amounts of gangue during the coal release process The conventional technique which involves visual inspection is not only labor intensive but also can introduce inaccuracies Coal and gangue identification methods
·Underground mining of thick coal layers with a thickness of more than m has operational technical safety and economic problems When the mining height exceeds m it is difficult to optimize the productivity and control surface stability due to the limitation of equipment design and surface conditions Hebblewhite et al 2002 2013 Top caving coal
·Application of Longwall Top Coal Caving in Challenging Geological Conditions Ning Shi Terra Energy LLC #29 206 BLK 13 Heping St Beijing China 10013 resulted in 18 fatality and USD4M value of equipment loss in Zhenxing Coal Mine Heilongjiang China on March 11 2013 Web 1 3 Best Practice for Challenging
·Steep coal seam mining activities will frequently occur during the next few decades in China In this study both experimental and numerical methods are employed to investigate the coal drawing from thick steep seam with longwall top coal caving mining A series of analyses is performed to investigate the features of the drawing body the distribution of top
·The theoretical equation of initial top coal boundary ITCB is one of the fundamental problems of top coal drawing law in longwall top coal caving LTCC mining The granular mechanical model of ITCB is established based on loose medium flow field theory By analysing the stressed top coal on ITCB along the section of coal seam thickness and face
·Here the longwall approx 86 m long is set up on the floor part of the seam and coal left on top is drawn through the roof support chute on the gob shield onto the front thickness of the seam is variable due to layer formation but it is m on average Fig 1 Of this 3 m is mined from the longwall the rest m caves The longwall equipment used
·Fully mechanized top coal caving mining is one of the main methods of thick seam mining 1 2 3 4 coal is the only load transfer medium between support and roof and its physical and
·The longwall top coal caving LTCC production method applied by forming a face in the horizontal thickness of the seam and also called horizontal section top coal caving especially in studies originating from China is widely used in the production of inclined and thick coal this production method in addition to the top coal losses that occur behind the
Longwall Top Coal Caving Longwall top coal caving LTCC is a special type of longwall mining applicable to very thick seams greater than where good quality coal is being left because "conventional" longwall equipment has not yet been designed to operate successfully beyond around 5m mining height It enables an increased recovery for
·The study has developed the key technologies for improving the reliability of equipment at the coal face and has overcome the challenges in equipping the top coal caving face with a large mining
·Among them the hydraulic support of top coal caving adopts the four column support shield type low top coal caving hydraulic support the specific model is ZF10000/20/32D intermediate frame 31
Height of water conducting zone is an important parameter for implementing water preserved mining techni cal measures In order to obtain the height of water conducting zone in longwall top coal mining caving mining face un der thick alluvium and soft overburden taking the 11915 working face of a mine as an example three method were used to observe the height of water
·The longwall top coal caving LTCC is a widely used method for producing thick coal seams This method is applied in two different ways in steeply inclined thick coal seams by forming a longwall at the horizontal thickness of the seam and the slope of the seam Key technologies and equipment for a fully mechanized top coal caving operation
The paper systematically summarized the main achievements of the fully mechanized longwall top coal caving technology in passed 20 years in China and the conclusion and understanding on the related issues The paper provided the issues of the theoretical and technical researches to be strengthened in the next step for the fully mechanized longwall top coal caving technology In
·Under the condition of fully mechanized top coal caving in close distance coal seams the surrounding rock of the stopping space easily loses stability during the withdrawal of mining equipment in the working face because the lower coal seam working face is located under the goaf and the overburden rock has a large range of complex interaction Field investigation
