Back-and-forth mining for hard and thick coal seams—research about the mining technology for fully mechanized caving working face of Datong Mine

The article introduced the key technology, mining process, and back-and-forth mining method for the caving working face of hard-thick coal seams in Datong mine, and researched this innovations process, optimized the systemic design and working face out-play, tried to perfect the caving mining technology of hard-thick coal seams further.

Systematic principles of surrounding rock control in longwall mining within thick coal seams

Effective surrounding rock control is a prerequisite for realizing safe mining in underground coal mines.In the past three decades, longwall top-coal caving mining(LTCC) and single pass large height longwall mining(SPLL) found expanded usage in extracting thick coal seams in China. The two mining methods lead to large void space left behind the working face, which increases the difficulty in ground control.Longwall face failure is a common problem in both LTCC and SPLL mining. Such failure is conventionally attributed to low strength and high fracture intensity of the coal seam. However, the stiffness of main components included in the surrounding rock system also greatly influences longwall face stability.Correspondingly, surrounding rock system is developed for LTCC and SPLL faces in this paper. The conditions for simultaneous balance of roof structure and longwall face are put forward by taking the stiffness of coal seam, roof strata and hydraulic support into account. The safety factor of the longwall face is defined as the ratio between the ultimate bearing capacity and actual load imposed on the coal wall.The influences provided by coal strength, coal stiffness, roof stiffness, and hydraulic support stiffness,as well as the movement of roof structure are analyzed. Finally, the key elements dominating longwall face stability are identified for improving surrounding rock control effectiveness in LTCC and SPLL faces.

Prediction of face advance rate and determination of the operation efficiency in retreat longwall mining panel using rock engineering system

A new approach for prediction of face advance rete (FAR) prior to mining operation and determination of the operation efficiency after mining operation in retreat longwall mining panel is presented based upon the concepts of rock engineering system (RES). For this purpose, six longwall panels considered in Parvadeh-I coal mine. Seven major effective parameters on FAR was selected including coal mine roof rating, gas propagation, safety factor of longwall face, ratio of joint spacing to cutting depth at longwall face, longwall face inclination, panel width, floor rock mass rating. To performance evaluation of the presented model, the relationship between the average vulnerability indexes of advance operation with FAR was determined in considered panels with coefficient of determination (R2) equal to 0.884 that indicate relatively acceptable correlation and compatibility. Investigations of the research indicated that it is possible to determine the actual operation efficiency under fair conditions by a RES-based model. The inevitable reduction of FAR for each longwall panel was determined by presented model that the difference amount between the maximum possible practical face advance rate (FARmpp) and recorded actual face advance rate (FARa) indicate the operation efficiency. Applied approach in this paper can be used to prediction of FAR in retreat longwall mining panel for same conditions that can have many benefits, including better and more accurate planning for the sales market and mine operation. Also, presented method in this paper can be applied as a useful tool to determination of actual operation efficiency for other sections and extraction methods in coal mines.

Ground pressure and overlying strata structure for a repeated mining face of residual coal after room and pillar mining

To investigate the abnormal ground pressures and roof control problem in fully mechanized repeated mining of residual coal after room and pillar mining, the roof fracture structural model and mechanical model were developed using numerical simulation and theoretical analysis. The roof fracture characteristics of a repeated mining face were revealed and the ground pressure law and roof supporting condi- tions of the repeated mining face were obtained. The results indicate that when the repeated mining face passes the residual pillars, the sudden instability causes fracturing in the main roof above the old goal and forms an extra-large rock block above the mining face. A relatively stable ＂Voussoir beam＂ structure is formed after the advance fracturing of the main roof. When the repeated mining face passes the old goaf, as the large rock block revolves and touches gangue, the rock block will break secondarily under overburden rock loads. An example calculation was performed involving an integrated mine in Shanxi province, results showed that minimum working resistance values of support determined to be reason- able were respectively 11,412 kN and 10,743 kN when repeated mining face passed through residual pillar and goaf. On-site ground pressure monitoring results indicated that the mechanical model and support resistance calculation were reasonable.

Prevention of gob ignitions and explosions in longwall mining using dynamic seals

Most, if not all longwall gob areas accumulate explosive methane-air mixtures that pose a deadly hazard to miners. Numerous mine explosions have originated from explosive gas zones(EGZs) in the longwall gob. Since 2010, researchers at the Colorado School of Mines(CSM) have studied EGZ formation in longwall gobs under two long-term research projects funded by the National Institute for Occupational Safety and Health. Researchers used computational fluid dynamics along with in-mine measurements. For the first time, they demonstrated that EGZs form along the fringe areas between the methane-rich atmospheres and the fresh air ventilated areas along the working face and present an explosion and fire hazard to mine workers. In this study, researchers found that, for progressively sealed gobs, a targeted injection of nitrogen from the headgate and tailgate, along with a back return ventilation arrangement, will create a dynamic seal of nitrogen that effectively separates the methane zone from the face air and eliminates the EGZs to prevent explosions. Using this form of nitrogen injection to create dynamic seals should be a consideration for all longwall operators.

The Recent Technological Development of Intelligent Mining in China

In the last five years, China has seen the technological development of intelligent mining and the application of the longwall automation technology developed by the Longwall Automation Steering Committee. This paper summarizes this great achievement, which occurred during the 12th Five-Year Plan （2011-2015）, and which included the development of a set of intelligent equipment for hydraulic-powered supports, information transfers, dynamic decision-making, performance coordination, and the achievement of a high level of reliability despite difficult conditions. Within China, the intelligent system of a set of hydraulic-powered supports was completed, with our own intellectual property rights. An intelligent mining model was developed that permitted unmanned operation and single-person inspection on the work face. With these technologies, the number of miners on the work face can now be significantly reduced. Miners are only required to monitor mining machines on the roadway or at the surface control center, since intelligent mining can be applied to extract middle-thick or thick coal seams. As a result, miners＇ safety has been improved. Finally, this Darter discusses theprospects and challenges of intelligent mining over the next ten years.

Mating model on production capacity for the system of cutting coal and drawing top-coal in FMMSC

Being a safe and highly-efficient mining method, fully mechanized mining with sublevel caving （FMMSC） was extensively employed in Chinese coal mines with thick seam. In order to make drawing top-coal furthest to parallel work with shearer cutting coal, decrease failure ratio of rear scraper conveyor and increase safe production capacity of equipments, based on production technology, set up the mating model of safe production capacity of equipments for the system of drawing top-coal and shearer cutting coal in coal face with sublevel caving. It is mean capability of drawing top-coal adapted to the capability of shearer cutting coal in a working circle in the coal face that was deduced. The type selection of equipment of rear scraper conveyor can be tackled with this mating model. The model was applied in FMMSC in Yangcun Coal Mine, Yima Coal Group of China. With the mating light-equipments, the coal output in coal face attained 1.05 Mt in 2004. It gained better technical-economic benefit.

煤矿井下非均匀照度图像去噪研究

煤矿综采工作面空间小、照明环境复杂多变,采煤过程中伴随着大量的粉尘、大雾,导致采集的图像出现曝光、细节特征减弱等问题,难以对井下照明区域光照强度过大的图像进行有效的特征提取。针对上述问题,提出了一种煤矿井下非均匀照度图像去噪算法。首先,将视频截取为图像,判断图像是否需要进行光照抑制,将需要进行光照抑制的RGB图像拆分通道,并计算每个通道的光照调节因子,实现图像的整体光照调节;然后,将未进行整体光照抑制的图像和经整体光照抑制的图像进行反射分量提取,即将输入的图像转换为HSV空间图像,使用单尺度Retinex(SSR)算法对V通道图像中的光照分量进行单独处理,将V分量中的入射分量去除,保留反射分量,并对反射分量使用直方图均衡算法实现光照均衡化处理;最后,使用基于引导滤波的暗通道先验算法对经过光照处理后的图像进行去雾处理,并使用伽马校正函数重新调节亮度不均的图像。主观评价结果表明:提出的煤矿井下非均匀照度图像去噪算法有效抑制了因光照导致整体亮度较高的问题,且由于大雾、粉尘等因素导致图像模糊的部分更加清晰,图像的细节特征更加突出。采用信息熵、均值、标准差、空间频率4种评价指标对提出的算法效果进行客观评价,结果表明,提出的算法在信息熵、均值、标准差、空间频率上较多尺度Retinex(MSR)算法分别平均提升了21.87%,-56.06%,153.43%,294.45%,较基于颜色保持的多尺度视网膜增强(MSRCP)算法分别平均提升了1.18%,-39.56%,33.29%,-4.71%,较带色彩恢复的多尺度视网膜增强(MSRCR)算法分别平均提升了38.06%,-55.27%,462.10%,300.96%,说明提出的算法能更有效地增加图像信息量、抑制光照强度、提升边缘信息及图像清晰度。

综放工作面围岩控制与智能化放煤技术现状及展望

分析了厚及特厚煤层智能化综放工作面围岩控制技术与智能化放顶煤技术发展现状及存在的问题,从巷道围岩高效支护、工作面超前支护、坚硬特厚顶煤冒放性、液压支架位姿监测及智能化放顶煤5个方面提出了工程实际需求。针对综放工作面实现安全、高效、智能化开采存在的技术难题与工程需求,对综放工作面围岩控制技术、智能化放煤技术进行了研究:构建了坚硬特厚煤层顶煤悬臂梁力学模型,研发了提高顶煤冒放性及放出率关键技术,实现了坚硬特厚煤层超大采高综放开采;研发了单元式超前液压支架顶梁可旋转自复位装置,实现了液压支架顶梁根据巷道顶板倾斜角度自动旋转支护,有效提高了单元式超前液压支架对巷道顶底板的适应性;提出了采用巷道支护液压支架替代传统锚网支护结构的思路,具有支护效率高、成本低、节省工作面超前支护等优点;开发了基于立柱与尾梁千斤顶行程的综放液压支架支护姿态监测装置与算法,提高了液压支架支护姿态解算效率与精度;提出了基于透明地质模型、煤量监测装置与煤矸识别装置融合的智能放煤控制方法,可有效解决多夹矸层特厚顶煤智能化放煤技术难题。提出智能地质保障技术、机器视觉精准测量与智能感知技术、综放工作面设备智能精准自适应控制技术、综放工作面数字孪生技术等是智能化综放开采技术与装备的发展趋势。

基于残差优化的综采工作面煤壁点云补全方法

煤矿综采工作面巷道的数字化三维重建过程中需要完整且密集的煤壁点云数据。受遮挡、视角限制等因素影响,采集的综采工作面煤壁点云数据往往不完整且稀疏,影响下游任务,需进行煤壁点云修复和补全。目前缺少针对井下点云补全任务的数据集和网络模型,现有模型用于煤壁点云补全时存在点云密度分布不均匀、点云特征信息丢失等情况。针对上述问题,设计了一种基于残差优化的煤壁点云补全网络模型,采用监督学习方式学习点云特征信息,通过最小化密度采样和残差网络迭代优化输出完整点云。采集煤矿井下真实综采工作面煤壁点云数据,预处理后筛选可用数据,通过模拟随机空洞制作煤壁点云缺失数据集,并用缺失数据集训练基于残差优化的煤壁点云补全网络模型。实验结果表明:与经典的FoldingNet,TopNet,AtlasNet,PCN,3D-Capsule点云补全网络模型相比,基于残差优化的煤壁点云补全网络模型针对构造的缺失煤壁点云和稀疏煤壁点云补全的倒角距离、地移距离及F1分数均能达到最优水平,整体补全效果最佳;针对实际缺失的煤壁点云,该模型能够实现有效补全。

特厚煤层工作面煤厚变化电磁波透视响应特征

目的为掌握煤厚变化对特厚煤层工作面电磁波透视探测的影响,以准确圈定地质异常区,保障工作面安全高效生产。方法根据煤层工作面地质条件,利用三维仿真软件,对煤厚变化进行了电磁波透视数值模拟,并结合工作面探查实例进行了分析。结果0~20m煤厚范围,随煤厚减小,电磁波透视场强值呈抛物线下降趋势,可分为缓慢降低(煤厚≥9m)、明显降低(9m>煤厚≥5m)和快速降低(煤厚<5m)3个范围。煤厚10m以上的工作面适合于依据相对煤层变薄程度和变薄区煤厚来分析透视电磁波响应:变薄程度>1/3正常煤厚且煤厚<8m的薄煤区有明显响应,变薄区煤厚越小,透视电磁波场强降低越显著。煤厚10m以下的工作面,可以仅依据相对煤层变薄程度分析透视电磁波响应:变薄程度>1/4正常煤厚的薄煤区有明显响应,变薄程度越大,透视电磁波场强降低越显著。陕西金源招贤矿业有限公司特厚煤层1304工作面探测实例表明:正常煤厚变化及薄煤区的电磁波响应特征与数值模拟结果一致;工作面物探圈定的落差1m以上断层及薄煤区范围,与实际揭露范围相吻合。结论利用煤厚变化电磁波响应特征能够可靠地探查特厚煤层工作面地质异常区范围。

刮板输送机技术发展历程(一)——国外技术

刮板输送机是井下采煤工作面的“脊梁”装备,它经历了6次技术变革,持续推动采煤工艺变革及生产效率持续提升。刮板输送机第1次技术变革发生于1900-1940年,诞生了可拆卸刮板输送机,煤矿开启半机械化开采时代;第2次技术变革产生于1940-1950年,创制了可弯曲刮板输送机,煤矿进入机械化开采时代;第3次技术变革形成于1950-1985年,创设了可自移刮板输送机,煤矿跨入综合机械化开采时代;第4次技术变革出现在1985-2000年,已发展成为重型化刮板输送机,煤矿走向高产高效综采时代;第5次技术变革形成于2000-2010年,研发出自动化刮板输送机,煤矿迈向数字化综采时代;第6次技术变革始于2010年,创新推出智能化刮板输送机,煤矿开启少人化智采时代。英国和德国为刮板输送机初创做出巨大贡献,研制出多种早期的刮板输送机机型。苏联对刮板输送机的系列化,以及对机械化采煤机的配套起到重要的创新推动作用。在此基础上,1954年,英国把安德顿滚筒采煤机与垛式支架、可弯曲刮板输送机组合为综合机械化采煤机组,建成世界上第一个综采工作面。21世纪以来,世界煤炭开采的重心逐步转向我国,国外刮板输送机研发与制造影响力逐年衰减,我国逐渐成为刮板输送机的制造强国。

两次采动影响下小煤柱巷道切顶卸压围岩控制技术

为解决多次采动影响下留小煤柱巷道矿压显现剧烈、围岩变形量大的问题,提出了“切顶卸压+顶、帮锚索补强”联合控制技术。以贾家沟煤矿10115运输巷为工程背景,分析了切顶卸压位置、高度与巷道围岩垂直应力分布的关系,给出切顶卸压关键参数,并研究了留小煤柱巷道在切顶卸压后受两次采动影响下的矿压显现规律。结果表明:切顶卸压后,煤柱上的应力峰值随切顶深度的增加呈指数降低;10115运输巷在邻近工作面一次采动过程中巷道围岩变形依次呈现出无变形、缓慢变形、快速变形和围岩稳定的变化规律,本工作面二次采动过程中巷道围岩变形依次呈现出明显变形和剧烈变形的规律;巷道围岩在受二次采动影响时变形更加剧烈,巷道变形量为一次采动时的3.0~7.5倍。

坚硬顶板切顶卸压技术对巷道围岩变形规律影响

针对特厚煤层坚硬顶板、宽煤柱条件下临空巷道面临的高围岩应力、大变形等问题,以老石旦煤矿16403综放工作面为工程研究背景,从宽煤柱顶板侧向破断结构角度对临空巷道大变形的影响因素进行了理论分析,采用数值模拟方法研究了对16402运输巷实施不同切顶卸压方案时,临近采空区的16403回风巷侧向顶板采动应力传递规律,并在现场施工水力压裂钻孔进行切顶卸压,实现临空巷道围岩变形控制。研究结果表明:“低位坚硬岩层悬臂梁+高位坚硬岩层砌体梁”破断结构是特厚煤层宽煤柱临空巷道大变形的主要原因,可采用切顶卸压技术破坏宽煤柱顶板侧向破断结构来控制临空巷道围岩大变形;切顶角变化可使关键块B长度发生改变,切顶角越大,则关键块B长度越小,临空侧顶板载荷向煤柱传递的程度越弱,临空巷道围岩承受的采动应力越小,切顶角为100°时临空巷道围岩垂直应力与变形量最小;在16402运输巷以切顶角100°施工水力压裂钻孔后,16403回风巷顶底板变形量较未实施切顶卸压的16402回风巷减小86.5%,两帮变形量减小87.1%,临空巷道围岩稳定性得到极大提高。

煤矿智能化开采技术现状及展望

煤矿智能化是实现煤炭行业高质量发展的核心技术支撑,是煤炭行业发展的必由之路。通过分析国内外智能化开采的研究现状,总结煤炭智能化开采取得的成果,分析智能化开采中的关键技术,包括煤矿地理信息系统、煤岩识别技术、工作面自动取直技术、机器人技术等。探讨了制约煤矿智能化发展的关键因素,从煤矿开采、数据通信、煤矿安全、煤矿机器人4个方面进行了展望。

综采工作面刮板输送机煤流时空分布研究

基于传感器的煤流特征研究受传感器监测范围有限的影响,无法对刮板输送机整机煤流特征进行研究;基于模型仿真的煤流特征研究缺乏对开采工艺的考虑,不能预测刮板输送机整机的煤流时空分布。针对综采工作面刮板输送机整机运载煤流特征难以监测的问题,结合综采工作面开采工艺,通过分析采煤机截割装载和刮板输送机运载煤流过程,建立了各工艺段下不同装载方式的刮板输送机瞬时装载体积、截面积的数学模型;将刮板输送机运载煤流过程划分为煤流平移和装载煤流叠加,基于有限元方法构建了综采工作面刮板输送机煤流时空分布预测模型。利用该模型仿真分析了开采工艺周期内刮板输送机的煤流时空分布特征:相比于中部正常截割阶段,端头截割阶段的煤流时空分布较为复杂;中部槽装载煤流的最大截面积出现在调换滚筒位置阶段;刮板输送机运载煤流体积在采煤机上行和下行过程中变化趋势相反,变化趋势由采煤机牵引方向决定。利用某矿工作面采煤机和刮板输送机实际运行数据作为模型的输入参数,根据预测的煤流时空分布计算过煤量,结果表明:过煤量预测结果与现场实测的变化趋势一致,累计过煤量预测误差为9.24%,在采煤机进刀过程和上行阶段的固定时间段内过煤量预测误差分别为13.19%和13.78%,证明了煤流时空分布预测模型的正确性。

基于OpenGL的三维地质建模及资源量估算

OpenGL是用于渲染2D、3D矢量图形的跨语言、跨平台的应用程序编程接口,常用于CAD、虚拟现实、科学可视化程序和电子游戏开发,可以与Visual C++紧密接口,便于实现机械手的有关计算和图形算法,可保证算法的正确性和可靠性,尤其是矿产资源估算中具有良好的应用效果。本文以Python软件平台为基础,以某内蒙古鄂尔多斯上湾煤矿为例,根据已有的煤矿煤层数据资料建立煤层三维地质数学模型,对综采面煤炭储量数据进行估算,并将矿井综采面实际掘进回采数据做为对照组,数据表明,该方法的较传统块段法更准确可靠。

煤矿大倾角综放工作面采煤参数及采煤工艺优化分析

以A煤矿26514工作面为例,介绍了一种基于有限元分析的煤矿大倾角综放工作面采煤参数及采煤工艺优化方法。该方法根据煤矿大倾角综放工作面参数构建相应的有限元模型,通过有限元模型的分析寻找现有工作面采煤参数与采煤工艺的缺陷,进而以此为基础制定工作面采煤参数与采煤工艺优化方案。研究对大倾角综放工作面的开采具有重要意义。

低瓦斯煤矿综采工作面采煤机综合控制研究

传统采煤机综合控制方法是直接建立综采滤波模型,未对采煤机综采参数进行提取,造成耗电量相对较高。提出对低瓦斯煤矿综采工作面采煤机综合控制进行研究。对采煤机综采参数进行提取,通过提取的采煤机综采参数建立综采滤波模型,确定获得的压力传感数据是否正确,最后利用该模型实现对低瓦斯煤矿综采工作面采煤机的综合控制,设计对比实验,证明该控制方法的控制效果更好,具有节能性。

煤矿综采工作面综合防灭火技术的应用研究

在煤矿综合开采过程中,因为井下大气中有大量的粉尘,并且有高浓度的气体,所以极易引发火灾,严重的话还会引发爆炸。为了避免发生这种事故,给企业造成巨大的人员伤亡和经济损失,保证煤矿综合开采工作的顺利进行,本文将重点放在煤矿综合开采工作面的综合防灭火技术研究,以煤自燃的原理及危害为基础,重点介绍了几种综采工作面的防灭火技术,并对其技术原理及注意事项等展开分析。同时,结合实际的工程案例,研究了防灭火技术在实际工作中的具体应用,采用“注氮”为主,“喷洒阻化剂”为辅,“束管监控”为保障的综合防灭火技术,可有效控制工作面CO、C2H4含量,消除煤层自燃隐患,为综采工作面防火工作提供参考。