Stability and control of room mining coal pillars-taking room mining coal pillars of solid backfill recovery as an example

The stability of room mining coal pillars during their secondary mining for recovering coal was analyzed. An analysis was performed for the damage and instability mechanism of coal pillars recovered by the caving mining method. During the damage progression of a single room coal pillar, the shape of the stress distribution in the pillar transformed from the initial stable saddle shape to the final arch-shaped distribution of critical instability. By combining the shapes of stress distribution in the coal pillars with the ultimate strength theory, the safe-stress value of coal pillar was obtained as 11.8 MPa. The mechanism of instability of coal pillar groups recovered by the caving mining method was explained by the domino effect. Since the room coal pillars mined and recovered by the traditional caving mining method were significantly influenced by the secondary mining during recovery, the coal pillars would go through a chain-type instability failure. Because of this limitation, the method of solid backfilling was proposed for mining and recovering room coal pillars, thus changing the transfer mechanism of stress caused by the secondary mining(recovery) of coal pillars. The mechanical model of the stope in the case of backfilling and recovering room coal pillars was built. The peak stress values inside coal pillars varied with the variance of backfilling ratio when the working face was advanced by 150 m. Furthermore, when the critical backfilling ratio was 80.6%, the instability failure of coal pillars would not occur during the solid backfill mining process. By taking Bandingliang Coal Mine as an example, the coal pillars' stability of stope under this backfilling ratio was studied, and a project scheme was designed.

Mining pressure monitoring and analysis in fully mechanized backfilling coal mining face-A case study in Zhai Zhen Coal Mine

Fully mechanized solid backfill mining(FMSBM) technology adopts dense backfill body to support the roof. Based on the distinguishing characteristics and mine pressure control principle in this technology, the basic principles and methods for mining pressure monitoring were analyzed and established. And the characteristics of overburden strata movement were analyzed by monitoring the support resistance of hydraulic support, the dynamic subsidence of immediate roof, the stress of backfill body, the front abutment pressure, and the mass ratio of cut coal to backfilled materials. On-site strata behavior measurements of 7403 W solid backfilling working face in Zhai Zhen Coal Mine show that the backfill body can effectively support the overburden load, obviously control the overburden strata movement, and weaken the strata behaviors distinctly. Specific performances are as follows. The support resistance decreases obviously; the dynamic subsidence of immediate roof keeps consistent to the variation of backfill body stress, and tends to be stable after the face retreating to 120-150 m away from the cut. The peak value of front abutment pressure arises at 5-12 m before the operating face, and mass ratio is greater than the designed value of 1.15, which effectively ensures the control of strata movement. The research results are bases for intensively studying basic theories of solid backfill mining strata behaviors and its control, and provide theoretical guidance for engineering design in FMSBM.

Vertical transportation system of solid material for backfilling coal mining technology

For transportation of solid backfill material such as waste and fly ash from the surface to the bottom of the shaft in a fully mechanized backfilling coal backfilling coal mining technology, we developed a new vertical transportation system to transport this type of solid backfill material. Given the demands imposed on safely in feeding this material, we also investigated the structure and basic parameter of this system. For a mine in the Xingtai mining area the results show that: (1) a vertical transportation system should include three main parts, i.e., a feeding borehole, a maintenance chamber and a storage silo; (2) we determined that 486 mm is a suitable diameter for bore holes, the diameter of the storage silo is 6 m and its height 30 m in this vertical transportation system; (3) a conical buffer was developed to absorb the impact during the feeding process. To ensure normal implementation of fully mechanized backfilling coal mining technology and the safety of underground personnel, we propose a series of security technologies for anti-blockage, storage silo cleaning, high pressure air release and aspiration. This vertical transporting system has been applied in one this particular mine, which has fed about 4 million tons solid material with a feeding depth of 350 m and safely exploited 3 million tons of coal.

Green coal mining technique integrating mining-dressing-gas draining-backfilling-mining

Aiming to address the following major engineering issues faced by the Pingdingshan No. 12 mine:(1) difficulty in implementing auxiliary lifting because of its depth(i.e., beyond 1000 m);(2) highly gassy main coal seam with low permeability;(3) unstable overlying coal seam without suitable conditions for implementing conventional mining techniques for protective coal seam; and(4) predominant reliance on ‘‘under three" coal resources to ensure production output. This study proposes an integrated, closed-cycle mining-dressing-gas draining-backfilling-mining(MDGBM) technique. The proposed approach involves the mining of protective coal seam, underground dressing of coal and gangue(UDCG), pressure relief and gas drainage before extraction, and backfilling and mining of the protected coal seam. A system for draining gas and mining the protective seam in the rock stratum is designed and implemented based on the geological conditions. This system helps in realizing pressure relief and gas drainage from the protective seam before extraction. Accordingly, another system, which is connected to the existing production system, is established for the UDCG based on the dense medium-shallow trough process. The mixed mining workface is designed to accommodate both solid backfill and conventional fully mechanized coal mining, thereby facilitating coal mining, USCG, and backfilling. The results show that: The mixed mining workface length for the Ji15-31010 protected seam was 220 m with coal production capacity 1.2 million tons per year, while the backfill capacity of gangue was 0.5 million tons per year. The gas pressure decreased from 1.78 to 0.35 MPa, and the total amount of safely mined coal was 1.34 million tons. The process of simultaneously exploiting coal and draining gas was found to be safe, efficient, and green.This process also yielded significant economic benefits.

Joint Bearing Mechanism of Coal Pillar and Backfilling Body in Roadway Backfilling Mining Technology

In the traditional mining technology,the coal resources trapped beneath surface buildings,railways,and water bodies cannot be mined massively,thereby causing the lower coal recovery and dynamic disasters.In order to solve the aforementioned problems,the roadway backfilling mining technology is developed and the joint bearing mechanism of coal pillar and backfilling body is presented in this paper.The mechanical model of bearing system of coal pillar and backfilling body is established,by analyzing the basic characteristics of overlying strata deformation in roadway backfilling mining technology.According to the Ritz method in energy variation principle,the elastic solution expression of coal pillar deformation is deduced in roadway backfilling mining technology.Based on elastic-viscoelastic correspondence principle,combining with the burgers rheological constitutive model and Laplace transform theory,the viscoelastic solution expression of coal pillar deformation is obtained in roadway backfilling mining technology.By analyzing the compressive mechanical property of backfilling body,the time formula required for coal pillar and backfilling body to play the joint bearing function in roadway backfilling mining technology is obtained.The example analysis indicates that the time is 140 days.The results can be treated as an important basis for theoretical research and process design in roadway backfilling mining technology.

Construction and stability of an extra-large section chamber in solid backfill mining

In solid backfill mining without gangue removal, the gangue is separated directly underground and backfilled into goaf. This necessitates the underground construction of an extra-large section chamber for separation equipments. For the construction of an extra-large section chamber in the Tangshan mine, we proposed an active support through a combination of bolting, anchor cables, lining, and a reinforced chamber floor by inverted arch pouring. ABAQUS software was used to analyze the surrounding rock deformation and the plastic zone development of the chamber under different excavation schemes.The best excavation scheme was determined, and the effectiveness of the combined supports was verified. In practice, the engineering installation showed good overall control of the movement of the surrounding rock, with roof-to-floor and side-to-side convergences of 154.6 and 77.5 mm, respectively,which meets the requirements for underground coal gangue separation.

煤电化基地大宗固废“三化”协同利用基础与技术

我国14个大型煤炭基地及89个大宗固体废弃物综合利用示范基地建设,标志着矿区大宗固废利用已被纳入全国战略发展布局。长期以来煤炭资源高强度的开发与利用,造成矿区浅埋煤层资源临近枯竭,煤电化基地大规模固废堆积及地表沉陷,已成为制约矿区绿色低碳、高质量发展的难题。大宗煤基固废协同利用与绿色充填是解放“三下一上”压煤,延长矿井服务年限,实现固废无害化、资源化、规模化“三化”利用的有效途径。基于产煤大省山西省、“华东能源粮仓”安徽两淮基地及宁东能源化工基地的煤基固废种类和产量,详细阐述了以煤矸石、粉煤灰、炉底渣、气化渣和脱硫石膏等为主要材料的煤基固废通过重金属吸附解吸和络合钝化技术实现无害化处置,列举煤基固废分类应用于低热值煤基固废发电、制备建筑材料如水泥、砖瓦等资源化利用途径,对比分析煤基固废采煤沉陷区复垦回填及井下充填规模化利用途径,突出煤基固废井下充填的优越性。基于煤电化基地深部煤炭资源,提出绿色充填开采理论与关键技术,包括深部煤矸石源头减量与采选充协同技术、充填材料高效制备与深部井下输送技术及煤基固废充填材料深部多场耦合机理,探究多源煤基固废从源头、过程到终端的深部充填开采全过程的技术原理与方法,以解决矿区深部井下充填的技术难题。根据宁东基地任家庄煤矿、山西省霍尔辛赫煤矿及淮北矿区地质条件和充填目的,分别提出超前钻孔注充低位充填方案、关键层非典型特征条件下多离层梯级注浆方案和煤基固废协同利用关键技术,综合矿山固废处置与利用、深部煤炭资源开发利用、地表沉陷控制、生态环境保护等优势,形成煤电化基地大宗固废协同利用与绿色开采模式,为煤炭开采高质量化和环境低损伤化提供参考。

建筑物下特厚煤层镁渣基全固废连采连充开采技术与实践

我国建筑物下压煤量巨大,同时煤矸石、粉煤灰等煤基工业固体废弃物排放量日益增加,严重制约地方经济社会发展。以榆林麻黄梁煤矿为试验矿井,针对其特厚煤层、建筑物下压煤、充填成本高等问题,提出了特厚煤层全固废连采连充开采技术。采用四阶段工序并将特厚煤层分为上、下2部分二次回采压覆煤炭,最大程度控制地面沉降。为降低充填原材料成本,采用化学优化剂对镁渣进行源头改性,抑制镁渣冷却粉化,稳定水化活性,协同粉煤灰、脱硫石膏等煤基固废,研发了改性镁−煤渣基胶凝材料。采用改性镁−煤渣基胶凝材料胶结煤矸石、粉煤灰制备了全固废充填材料。针对麻黄梁煤矿四阶段强、弱充填强度要求,设计不同配比的改性镁渣基充填材料试验,优选配比并应用于井下充填。论述了膏体充填系统与充填接顶方法。麻黄梁煤矿全固废胶结充填工艺试验显示,井下28 d龄期充填体钻芯平均单轴抗压强度超设计强度27%,钻芯浸出毒性满足相关国家标准要求,成功回收了建筑物下压覆煤炭资源,社会经济效益显著。麻黄梁煤矿特厚煤层全固废胶结充填开采实践为国内类似矿井提供了有益借鉴,同时为我国大型煤炭基地的“煤−电−化−冶”固废大规模资源化利用提供了新的思路。

面间煤柱与顺槽“掘-充-留”一体化科学问题与技术

我国将煤炭作为兜底保障能源的局面短期内无法改变,仍将长时间面临煤炭资源保护与煤基固废利用率低的难题。通过创新采掘方法,同时实现提高煤炭资源回采率、规模化处置煤基固废,为煤炭行业绿色可持续发展提供了新途径。在深入调研煤炭资源开采技术发展现状的基础上,提出了煤矿“掘-充-留”掘进新工法。从大断面巷道快速掘进、连续高效充填和巷道安全留设3个方面,通过理论分析、数值模拟等手段,系统论述了“掘-充-留”工法的科学问题和关键技术,研究结果表明:①针对大断面巷道快速掘进、掘进工作面围岩稳定性控制等工程难题,凝练了煤岩特性与掘进机截割参数匹配机制、覆岩载荷空间传递机制与围岩变形机理、锚杆/索-顶板相互作用关系及支护机制3个科学难题,构建了以掘进区地质环境超前实时感知、落-装-运煤多工序智能协同作业、钻锚支架随掘随支围岩时效控制和大断面巷道防漏风及通风优化为核心的技术体系;②从大断面巷道承载体系及时构建及其承载性能调控两个方面凝练了连续高效充填的科学问题,包括充填体-煤层-锚杆/索协同承载机制、多元固废基充填材料水化固结机制,明晰充填体物理力学特性时空演化规律,建立了充填空间安全高效搭建、充填材料工作性能调控、充填材料流动-固结感知为核心的连续高效充填关键技术体系,相关理论与技术的突破可以为充填材料的原材料优选及配比设计、添加剂开发/选型及工作性能调控、掘进速率及充填步距优化设计、充填体固结监测等提供基础理论依据;③基于巷道安全留设及全生命周期内围岩易断裂、易片帮和易损伤等关键难题,阐述了巷道围岩应力场时空分布特征、巷道变形与损伤演化机制、巷道围岩工程质量监测与稳定性调控理论3个科学问题,形成了以巷道围岩稳定性智能预警、巷道围岩变形控制为核心的关键技术体系。开展煤矿“掘-充-留”工法的科学研究与工程示范,实现固废规模化处置-面间煤柱高效回收-顺槽快速掘进的协同,可以推动煤炭行业绿色低碳转型发展。

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。

固体充填采煤充填体与围岩相互作用时空演化特征研究

基于某煤矿7203w回采工作面工程条件,结合有限差分软件,分析了不同空间位置、不同时间阶段覆岩运动变化特征及充填体应力变化规律,提出了基于充填体与围岩相互作用时空效应的控顶优化设计方法。研究表明:沿工作面走向和倾斜方向,越靠近中部位置,直接顶下沉量越大,充填体应力也越大;在沿工作面走向上,距始采线和停采线50 m范围内,直接顶下沉值及充填体应力变化幅度较大,在中部100 m范围内直接顶下沉值变化不大;沿工作面倾斜方向上,距工作面两端25 m范围内,直接顶下沉值变化幅度较大,在中部40 m范围内直接顶下沉值变化不大;“核心区”充实率88%、“次核心区”充实率83%、“边界区”充实率80%,控顶优化设计方案的最终实际控制充实率为90.4%,满足工程要求。研究成果可为固体充填采煤技术的控顶设计提供理论支撑。

煤矿井下复杂地形条件综采面综采技术的应用研究

综采技术应用与煤矿井下综采作业的生产效率、生产安全息息相关,煤矿生产中,综采技术应用是核心要素,在煤矿井下复杂地形的条件下,利用综采工作面的综采技术,要制定恰当、可行的技术方案,考虑到地形条件较为复杂,在综采技术应用中需要明确支护方案的作业流程,强调支护规范性,提高生产质量和井下综采的作业效率与安全性。本文分析了综采面巷道支护方案及技术优势,提出了煤矿井下复杂地形条件的综采面综采技术应用要点。

综合机械化固体充填采煤技术研究

在现代化的煤矿生产中,为了确保煤炭生产的总体质量,必须遵守“高效率、高产出”的原则,严格控制岩层的运动,采用先进的开采设备,以避免巷道出现塌陷断裂。在可持续发展的前提下,还要关注煤炭的开采环境,以防止其对中国的不可再生资源造成损害。基于此,针对综合机械化固体充填采煤技术展开了相关的研究,以期提高煤矿的开采效率和安全性。

综放工作面回撤期间防灭火技术研究

煤矿开采是一项复杂且对技术要求较高的工作,实际开展期间受各项因素影响,容易发生事故,不仅会影响煤矿开采,甚至会造成人员伤亡,危害巨大,因此,在煤矿开采期间必须做好相关内容的探讨,做好分析工作。在概述回撤期间做好灭火的意义基础上,依据工程实例对综放工作面回撤期间防灭火技术进行了深入探讨,希望文中内容对相关工作人员能够有所帮助。

冲击性煤层综放面采空区漏风区域识别及控制方法研究

矿井煤层发生冲击失稳易诱发矿压灾害,且工作面间煤柱破碎形成漏风通道,采空区自燃危险性增强。以孟村煤矿401103深埋冲击倾向性超长工作面为工程背景,通过分析工作面开采时漏风及煤自燃诱因,测定工作面及相邻采空区的漏风规律并数值模拟验证煤自燃危险区域,从而制定漏风控制及煤自燃防控措施。结果表明:401103工作面受冲击矿压影响较大,漏风供氧增加了采空区遗煤自燃的风险;漏风观测数据表明面间煤柱存在漏风通道,使得两工作面采空区形成了复合漏风采空区;在401103工作面推进过程中,煤自燃危险区域主要集中于工作面后部采空区,工作面进风隅角与其临近的401102采空区产生明显的漏风涡流区。采用束管监测、漏风封堵、材料阻化与调节风量等综合防控措施,有效控制了工作面及相邻采空区的遗煤自燃,保证了工作面的安全开采。

急倾斜煤层综合机械化采煤设备三机优化配套研究

常规的综采设备三机配套方法以开采效率优化为主,并未考虑三机生产能力配套问题,会影响三机运行性能。因此,设计急倾斜煤层综合机械化采煤设备三机优化配套方法。选择急倾斜煤层综采设备三机配套型式,根据煤层硬度、厚度、倾角等地质条件,选择合适的采煤机、液压支架、输送机等设备型式,确保三机结构尺寸配套。调整综合机械采煤设备三机配套参数,调整液压支架工作阻力、支护强度、采煤机截割速度、牵引速度等参数,使三机性能配套。匹配综采煤设备三机采支落煤输送生产能力,根据采煤机采煤能力小于输送机运输能力的原则,使三机生产能力配套。实例分析结果表明,该方法的优化配套效果更佳,能应用于实际生产。

煤基固废充填开采技术研究进展与展望

煤基固废充填开采技术符合煤炭绿色智能开采和洁净高效低碳利用行业主要攻关方向及新发展理念要求,是促进煤炭开采高质量化、环境低损伤化、绿色低碳化发展的研究重点与热点。笔者在总结煤基固废充填开采技术研发背景与发展历程的基础上,系统性介绍了煤基固废充填开采技术体系的研究现状,经过20余年产学研用联合攻关,历经5代技术的研发创新,已基本形成体系的典型固废充填技术包括综合机械化固体充填、膏体充填、长壁逐巷胶结充填、覆岩隔离注浆充填、井下采选充+X,为“三下”开采、条带煤柱回收、岩层移动与地表变形控制、煤基固废井下处置提供了较全面的技术途径;煤基固废充填开采充填材料本构模型、关键岩层控制及地表变形控制等理论研究也取得了较大进展,基本构建成充填开采岩层控制理论体系;面临产业智能化升级、深部资源开采、煤基固废规模化处置与资源化利用等重点发展趋势,煤基固废充填开采技术的主要发展方向包括但不限于煤基固废高效智能充填、井下嗣后注浆充填处置、深部充填采热、煤基固废充填井下碳封存、煤基固废绿色功能材料井下利用等。现有研究现状及发展趋势综合表明:煤基固废充填开采技术是实现煤炭资源绿色智能高效开采的重要代表性途径。

综合机械化固体充填采煤一体化技术

为推广应用综合机械化固体充填采煤一体化技术,解放"三下"压煤,提高矿井采出率,实现矿山的绿色开采,在简要综述充填采煤历程和发展现代化充填采煤技术的目标、要求和难点的基础上,系统阐述了综合机械化固体充填采煤一体化技术的系统布置、关键装备,并介绍了该技术在密集建筑群下、邻近松散含水层区域和大型河堤下进行大规模充填开采煤炭的工程实例。应用结果表明:综合机械化固体充填一体化采煤技术可实现"三下"压煤的安全高效开采,具有广阔的应用前景。

综合机械化固体充填采煤方法与技术研究

简要回顾了充填采矿的发展历程,指出了开发充填采煤技术的两大难点,即建立充填采煤的岩层控制理论和解决将充填体进入采空区的空间、通道和动力等技术途径;建立了固体充填采煤岩层移动控制和地表沉陷预计的等价采高方法;提出了能与传统综合机械化采煤技术相适应的综合机械化固体充填原理和方法,并介绍了自行研发的相关充填采煤系统和装备。工业性应用实践表明,综合机械化固体充填采煤除具有密实充填严格控制岩层移动和地表沉陷优点外,还能实现高产、高采出率采煤等良好的经济效益以及环境效益。