Zonal extraction technology and numerical simulation analysis in open pit coal mine

In order to enhance coal recovery ratio of open pit coal mines, a new extraction method called zonal mining system for residual coal around the end-walls is presented. The mining system can improve economic benefits by exploiting haulage and ventilation roadways from the exposed position of coal seams by utilizing the existing transportation systems. Moreover, the main mining parameters have also been discussed. The outcome shows that the load on coal seam roof is about 0.307 MPa and the drop step of the coal seam roof about 20.3 m when the thickness of cover and average volume weight are about 120 m and 0.023 MN/m³ respectively. With the increase of mining height and width, the coal recovery ratio can be improved. However, when recovery ratio is more than 0.85, the average stress on the coal pillar will increase tempestuously, so the recovery ratio should also be controlled to make the coal seam roof safe. Based on the numerical simulation results, it is concluded that the ratio of coal pillar width to height should be more than 1.0 to make sure the coal pillars are steady, and there are only minor displacements on the end-walls.     

我国大型露天煤矿若干生产工艺问题分析

对我国大型露天煤矿近些年出现并引起重视的生产工艺和技术问题进行了分析研究．认为将土地复垦纳入采矿工程中来实现“边开采、边复垦”的一体化作业，以缩短复垦周期和提高土地复垦率是我国大型露天煤矿区今后开展地土复垦工作的关键；采用地下台阶式开采法回采露天矿端帮煤可大大提高煤炭资源回收率和矿山经济效益；我国已经或将要开发的适宜露开天采的大型、特大型煤矿中，拉斗铲倒剥离工艺应用的条件已经具备，在这些矿区的设计与建设过程中，应对该工艺给予重视，大胆引用。     

Top coal caving mining technique in thick coal seam beneath the earth dam

It is important to study the mining technology under structures for raising the coal resources recovery ratio. Based on the geological and mining conditions, the top coal caving harmonic mining technique in thick coal seam beneath the earth dam was put forward and studied. The 5 factors such as the panel mining direction, panel size, panel location, panel mining sequence and panel advance velocity were taken into account in this technique. The dam movement and deformation were predicted after the thick coal seam mining and the effects of mining on the dam were studied. By setting up the surveying stations on the dam, the movement and deformation of the dam were observed during mining. By taking some protective measures on the dam, the top coal caving mining technique in thick coal seam beneath the earth dam was carried out successfully. The study demonstrates that harmonic mining in thick coal seam is feasible under the dam. The safety of the earth dam after mining was ensured and the coal resources recovery ratio was improved.     

近水平露天煤矿端帮靠帮开采方式与剥采比研究

运用露天采矿学的基本原理,提出了端帮靠帮开采的基本方法、实现形式、基本条件以及靠帮开采的意义,给出了靠帮开采剥采比的概念;在单一煤层和复合煤层情况下,推导出了2种端帮靠帮开采方式的靠帮开采剥采比计算公式,建立了不同煤层厚度和覆盖物厚度对靠帮开采剥采比影响趋势预测的数学模型和图示方法.结果表明：在近水平露天煤矿实施端帮靠帮开采,可以降低剥采比,提高煤炭资源回收率和经济效益,同时也丰富了露天开采方法与设计理论.     

Comparative study of mining methods for reserves beneath end slope in flat surface mines with ultra-thick coal seams

The paper aims to identify a reasonable method for mining ultra-thick coal seams in an end-slope in surface mine, With a case study of Heidaigou surface coal mine(HSCM), the paper conducted a comparative research on three mining methods, namely Underground Mining Method(UMM), Highwall Mining System(HMS) and Local Steep Slope Mining Method(LSSMM). A model was firstly established to simulate the impact that UMM and HMS exert on monitoring points and surface deformation. The way that stripping and excavation amount varies with different slope angle, and the corresponding end slope stability were analyzed in the mode of LSSMM. Then a TOPSIS model was established by taking into account six indicators such as recovery ratio, technical complexity and adaptability, the impact on surface mining production, production safety and economic benefits. Finally, LSSMM was determined as the best mining method for mining ultra-thick coal seams in end slope in HSCM.     

Suitable retention and recovery technology of floor coal at ends of fully mechanized face with great mining heights

Gateways at faces of great mining heights are mostly driven along the roof of coal seams. For gateway height restrictions, a 1-3 m floor coal is retained, leaving a triangular floor coal at the face ends, causing a loss of coal. In order to improve coal recovery rates and to ensure efficiency of equipment at coal mining faces, we investigated suitable retention methods and recovery technology of floor coal at face ends. The upper floor coal can directly be recovered by a shearer with floor dinting. The lower floor coal is recovered by shearer with floor dinting after advanced floor dinting and retaining a step for protecting coal sides in a haulage gateway. Field practice shows that this method can improve the coal recovery rates at fully mechanized working faces with great mining heights.     

Application of open-pit and underground mining technology for residual coal of end slopes

Given the conditions of residual coal from the boundary of a flat dipping open-pit mine,which uses strip areas mining and inner dumping with slope-covering,we propose an open-pit and underground integrated mining technology for residual coal of end slopes.In the proposal a conveyance road and ventilation conveyance near the slope are built,corresponding to the pit mining area and the surface coal mine dump,as well as an interval haulage tunnel and air-inlet tunnel.The outcome shows that such mining method may reduce the effect to slope stability from underground mining,it does not affect the dumping advance and has a high recovery rate of residual coal resources.The working face is timbered by single hydraulic props,transported by a scraper conveyor and supported by coal walls.This method of mining is one of layered top coal caving,with high resource recovery,low production cost where positive economic benefit can be realized.     

分级循环荷载下保护层开采扰动煤岩强度及裂隙特性研究

针对回采时反复采动作用下的保护层开采扰动煤岩极易诱发巷道围岩失稳的问题,采用分级循环荷载模拟实际回采工程中采动应力的长期作用,研究保护层开采扰动煤岩在循环荷载作用下的力学强度及变形破坏特性. 试验结果表明,在加卸载过程中,受保护层开采扰动煤样的体积膨胀变形明显,煤样内部结构破坏程度比未受保护层开采扰动煤样更高. 在加卸载后期,受保护层开采扰动煤样表现为塑性破坏,未受保护层开采扰动煤样发生明显的脆性破坏. 相比于未受保护层开采扰动煤样,受保护层开采扰动煤样的峰值强度下降,单位体积（直径为50 mm,高度为100 mm）内的煤样裂隙体积显著增加,峰值强度和裂隙体积占比均沿煤层走向分布较为均匀. 处于断层带的未受保护层开采扰动煤样的彼此物性差异较大. 受保护层开采扰动煤样比未受保护层开采扰动煤样更符合“煤岩破坏时,裂隙空间复杂程度与峰值强度存在反向对应分布”规律.     

安家岭露天煤矿端帮采煤方法研究

将井工开采的放顶煤采煤技术应用于平朔安家岭露天煤矿端帮煤开采,提出了“煤墙支撑简易放顶煤”采煤法。该法将煤层全厚分为上下两个采掘层,每个采掘层又分为上下两个分层,采掘下分层时用单体液压支架支护,采掘上分层时采用顶板放炮民落煤,采掘的煤层厚度可达10m以上,此种采煤方法具有安全可靠,资源回收率高、作业效率高等优点。     

"3-Section" Technology of Full-Dimension Mining in Flat Thick-Seam

To raise coal recovery ratio and solve the key problem of full-dimension mining, a new "3-section" technology of full-dimension mining is put forward in flat thick-seam according to the theory and mining practice. This technology is proved to be rational and feasible in rodway layout system of stagger arrangement.     

煤矿开采沉陷有效控制的新途径

开采沉陷是造成矿区环境地质灾害的直接根源，有效控制和减轻地面沉陷程度是减轻或避免开采沉陷环境灾害的根本之路，针对这一问题，分析了充填开采、条带开采和覆岩离层注浆岩层控制技术的优缺点，根据荷载置换原理，提出了“条带开采一注浆充填固结采空区—剩余条带开采”的三步法(二次条带式)开采沉陷控制的新思路，进行了三步法开采沉陷控制的可行性研究，初步分析表明，采用三步法开采可以实现对岩层移动和地表沉陷的有效控制，地表下沉系数可控制在0．25左右，煤炭采出率可达到80％～90％，可基本实现地面建筑物不搬迁和大幅度减轻土地塌陷灾害。     

Surrounding rock control of gob-side entry driving with narrow coal pillar and roadway side sealing technology in Yangliu Coal Mine

Gob-side entry driving can increase coal recovery ratio, and it is implied in many coal mines. Based on geological condition of 10416 working face tailentry in Yangliu Coal Mine, the surrounding rock deformation characteristics of gob-side entry driving with narrow coal pillar is analysed, reasonable size of coal pillar and reasonable roadway excavation time after mining are achieved. Surrounding rock control technology and effective roadway side sealing technology are proposed and are taken into field practice. The results showed that a safer and more efficient mining of working face can be achieved. In addition, results of this paper also have important theoretical significance and valuable reference for surrounding rock control technology of gob-side entry driving with narrow coal pillar under special geological condition.     

建筑物下煤炭资源回收难易程度模糊综合评价

分析了建筑物下煤炭资源回收难易程度的影响因素 ,讨论了采用权重分析法确定各影响因素权重的过程 ,在此基础上阐述了建筑物下煤炭资源回收难易程度的模糊综合评价方法 ,并结合实例进行了验证 .研究结果对合理计算和征收建筑物下煤炭资源补偿费、对搞好矿产资源管理和提高建筑物下采煤方案的科学决策水平提供了理论与方法依据 .     

Developing selective mining capability for longwall shearers using thermal infrared-based seam tracking

Longwall mining continues to remain the most efficient method for underground coal recovery. A key aspect in achieving safe and productive longwall mining is to ensure that the shearer is always correctly positioned within the coal seam. At present, this machine positioning task is the role of longwall personnel who must simultaneously monitor the longwall coal face and the shearer’s cutting drum position to infer the geological trends of the coal seam. This is a labour intensive task which has negative impacts on the consistency and quality of coal production. As a solution to this problem, this paper presents a sensing method to automatically track geological coal seam features on the longwall face, known as marker bands, using thermal infrared imaging. These non-visible marker bands are geological features that link strongly to the horizontal trends present in layered coal seams. Tracking these line-like features allows the generation of a vertical datum that can be used to maintain the shearer in a position for optimal coal extraction. Details on the theory of thermal infrared imaging are given, as well as practical aspects associated with machine-based implementation underground. The feature detection and tracking tasks are given with real measurements to demonstrate the efficacy of the approach. The outcome is important as it represents a new selective mining capability to help address a long-standing limitation in longwall mining operations.     

Longwall mining under gateroads and gobs of abandoned small mine

Due to the use of outdated mining technology or room and pillar mining process in small coal mines, the coal recovery ratio is only 10–25%. In many regions of China, the damage area caused by the small coal mines amounted to nearly one hundred square kilometers. Therefore, special mining techniques must be taken to reclaim the wasted resource in disturbed coal areas. This paper focuses on the different mining methods by analyzing the longwall panel layout and abandoned gateroad(AG) distribution in the abandoned area of Cuijiazhai coal mine in northwestern China. On the basis of three-dimensional geological model, FLAC3 D numerical simulation was employed. The abutment pressure distribution was simulated when the panel face passed through the disturbed areas. The proper angle of the inclined face was analyzed when the panel face passed through the abandoned gateroads. The results show that the head end of the face should be 13–20 m ahead of the tail end. The pillars on both sides of abandoned gateroads had not been damaged at the same time, and no large-area stress concentration occured above the main roof.Therefore, the coal reserves of disturbed areas can be successfully recovered by using underground longwall mining.     

放顶煤开采采出量与采出率计算精度的探讨

针对现行放顶煤开采采出量及采出率确定方法,推导出了其计算值的误差估计模型;根据兖州南屯矿实际数据,计算出了误差估计模型中的相应参数（即由统计产量折算实测产量所需参数）的相似维、实验及理论变异函数;基于地质统计学理论,得到了3种采样方法、不同采样间距与上述参数的估计误差、采出量相对误差的关系。研究表明,采用地质统计学、分形几何、误差理论等方法,可以有效地解决放顶煤开采采出量的误差估计、测量或采样最佳方案选取及有关标准制定问题,具有重要的实用价值与学术价值。     

锚杆加固条带煤柱的离散元模拟分析

结合煤巷锚杆支护技术与条带开采技术，首次提出了用锚杆加固条带煤柱的新方法。离散元数值模拟结果表明，采用这一方法，不仅可以提高煤柱的稳定性和承载能力，减轻采动损害，还可将煤柱缩小一定尺寸，提高回采率，在“三下”采煤中有着广阔的应用前景。     

露天矿端帮采煤与露天采排工程的时空关系

分析了安家岭露天煤矿端采煤与露天采排工程的时空关系,解释了露天采、剥、排工程如何在时间和空间上影响端帮采煤的开采强度、回采率等主要技术参数,得出的结论对开采近水平矿床的露天煤矿具有普遍意义。     

Numerical investigation on the caving mechanism with different standard deviations of top coal block size in LTCC

The size distribution of the broken top coal blocks is an important factor, affecting the recovery ratio and the efficiency of drawing top coal in longwall top coal caving(LTCC) mining panel. The standard deviation of top coal block size(dt) is one of the main parameters to reflect the size distribution of top coal. To find the effect of dton the caving mechanism, this study simulates experiments with 9 different dtby using discrete element software PFC. The dtis divided into two stages: uniform distribution stage(UDS) whose dtis less than 0.1(Schemes 1–5), and nonuniform distribution stage(NDS) whose dtis more than 0.1(Schemes 6–9). This research mainly investigates the variation of recovery ratio, drawing body shape,boundary of top coal, and contact force between particles in the two stages, respectively. The results showed that with the increasing dt, the recovery ratio of the panel increases first and then decreases in UDS. It is the largest in Scheme 3, which mainly increases the drawing volume at the side of starting drawing end. However, the recovery ratio decreases first and then increases quickly in NDS, and it is the largest in Scheme 9, where the drawing volume at the side of finishing drawing end are relatively higher. In UDS, the major size of top coal is basically medium, while in NDS, the size varies from medium to small, and then to large, with a distinct difference in shape and volume of the drawing body. When the major size of top coal is medium and small, the cross-section width of the initial boundary of top coal at each height is relatively small. Conversely, when the top coal size is large, the initial boundary of top coal has a larger opening range, the rotating angle of lower boundary is relatively small in the normal drawing stage, which is conducive to the development of drawing body and reduces the residual top coal, and the maximum particle velocity and the particles movement angle are both larger. This study lays a foundation for the prediction of recovery ratio, and suggests that the uniform top coal is more manageable and has a larger recovery ratio.     

露天煤矿端帮残煤开采及边坡暴露时间分析

为了提高露天开采的煤炭资源回收率，掌控露天煤矿端帮残煤开采工程安排，提出了水平和近水平大型露天煤矿汽车运输内排条件下，露天煤矿端帮露井联采、端帮陡帮开采、减少露天煤矿端帮边坡暴露时间的措施．结果表明：采掘工作帮帮坡角越大、内排土场工作帮帮坡角越大、工作线推进强度越大、内排土场下部水平排土台阶高度越大、采场坑底宽度越小露天煤矿端帮边坡的暴露时间越短；当露天煤矿端帮实行陡帮开采时，汽车运输内排通路可设在采场中部回填搭建。