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.

Thermal recovery process of a backfilled open-pit in permafrost area at the Gulian strip coal mine in Northeast China

Timely and proper backfilling of open-pits in strip coal-mines has been an effective measurement for the recovery of the hydrothermal regimes and ecological environment in permafrost regions. In this study, numerical simulations and statistical regressions were applied for analyzing the recovery processes of the backfill and its major influencing factors for the thermal equilibrium in recently backfilled open pits at the Gulian strip coalmine in Mo'he, Northeast China. Results show that the thermal recovery time of backfilled areas is positively correlated to the backfill depth(BD) of the soils, the backfilled soil temperature(BST), and the mean annual ground surface temperature(MAGST); meanwhile, climate warming can impact on thermal regimes of the backfill area. The impact of climate warming on ground temperature of the backfill will show up significantly in about 50 years afterbackfilling(BD at 10.0 and 20.0 m, BST at 20.0°C) under the climate warming scenario(CWS) of 0.025°C·year ^(-1). Grey-relation analyses show that the sensitivity of the backfill recovery time declines in the order of the BD, BST and MAGST. On the basis of the abovementioned studies, the layer-by-layer backfilling in cold seasons is advised for more effective and more rapid recovery of thermal regimes of the backfilled open-pits in cold regions.

Stability analysis of rib pillars in highwall mining under dynamic and static loads in open‑pit coal mine

The retained coal in the end slope of an open-pit mine can be mined by the highwall mining techniques.However,the instability mechanism of the reserved rib pillar under dynamic loads of mining haul trucks and static loads of the overlying strata is not clear,which restricts the safe and efcient application of highwall mining.In this study,the load-bearing model of the rib pillar in highwall mining was established,the cusp catastrophe theory and the safety coefcient of the rib pillar were considered,and the criterion equations of the rib pillar stability were proposed.Based on the limit equilibrium theory,the limit stress of the rib pillar was analyzed,and the calculation equations of plastic zone width of the rib pillar in highwall mining were obtained.Based on the Winkler foundation beam theory,the elastic foundation beam model composed of the rib pillar and roof under the highwall mining was established,and the calculation equations for the compression of the rib pillar under dynamic and static loads were developed.The results showed that with the increase of the rib pillar width,the total compression of the rib pillar under dynamic and static loads decreases nonlinearly,and the compression of the rib pillar caused by static loads of the overlying strata and trucks has a decisive role.Numerical simulation and theoretical calculation were also performed in this study.In the numerical simulation,the coal seam with a buried depth of 122 m and a thickness of 3 m is mined by highwall mining techniques.According to the established rib pillar instability model of the highwall mining system,it is found that when the mining opening width is 3 m,the reasonable width of the rib pillar is at least 1.3 m,and the safety factor of the rib pillar is 1.3.The numerical simulation results are in good agreement with the results of theoretical calculation,which verifes the feasibility of the theoretical analysis of the rib pillar stability.This research provides a reference for the stability analysis of rib pillars under highwall mining.

西湾露天煤矿剥采边帮涌水超前治理技术研究与应用

为有效治理露天煤矿剥采面临的边帮涌水水害问题,以西湾露天煤矿边帮涌水治理为工程背景,通过抽水试验法和瞬变电磁法确定风化基岩和烧变岩地层为受注地层;利用钻孔电视成像仪对治理地层裂隙发育情况进行了探查,根据裂隙发育特征和露天煤矿爆破剥采方式综合确定了帷幕墙设计参数和超前预注浆施工工艺。结果表明:超前注浆治理工程实施后,受注地层透水率降为1.95~6.11 Lu,对应渗透系数小于0.0001 cm/s,矿坑东侧抽排水量基本稳定在10884 m^(3)/d,治理范围内仅1处出水点较前期堵水阶段减水率达92.12%,说明超前预注浆治理技术构建帷幕墙能够大幅增加浆液留存率,可对裂隙进行有效充填,阻隔地下水在边帮涌出。

广西西湾煤系首次发现牙形刺及其地层意义

西湾煤系是广西重要含煤层位之一,以碳酸盐岩夹煤层为特征,自下而上分天堂组和大岭组,主要煤层赋存于大岭组中。煤系时代有晚三叠世与早侏罗世之争。1988年笔者之一冯少南,曾报道了天堂组产植物化石Danaeopsis fecunda Halle,为煤系时代归属提供了重要古生物依据。今年笔者在大岭组的灰岩中分析出牙形刺,认为大岭组的时代应属晚三叠世,并进一步说明大岭组为潮坪泻湖→滨海沼泽相沉积。

DISCOVERY OF Danaeopsis fecunaa HALLE FROM THE XIWAN COAL SERIES IN GUANGXI AND ITS SIGNIFICANCE

The Xiwan coal series is an important coal-bearing sequence in Guangxi, which consists of carbonate rocks, intercalated with coals. The upper part of the Xiwan coal series is known as the Daling Formation and the lower part of it as the Tiantang Formation. The overlying strata are represented by the Shiti Formation. There

FCC油浆与煤共炼试验研究

通过在150 kg/d悬浮床加氢试验评价装置上开展某炼油厂FCC油浆与西湾煤共炼试验,研究FCC油浆与西湾煤共炼时的匹配性,剖析油煤浆成浆性和油煤共炼的试验结果,为煤直接液化新途径的开发提供基础数据。试验结果表明,该炼油厂FCC油浆与西湾煤共炼时,油煤浆浓度高达45%时,依然具有稳定的成浆性,油煤浆中加入0.55%活性炭添加剂、1.80%赤泥催化剂(以原料量为基准),在反应空速为0.5 h^(-1)、反应温度468℃、氢油比3000 L/kg的反应条件下,整体液体收率为72.93%,煤转化率为88.8%。与传统煤直接液化相比,FCC油浆与西湾煤共炼具有耗氢量低、液体收率高、煤转化率高的优势。

Web pillar stability in open‑pit highwall mining

When highwall mining technology is applied to recover large amounts of residual coal left under the highwall of a big openpit mine,a reasonable coal pillar width is required to ensure the stability of the web pillars.Using numerical simulations,this paper studied the characteristics of the abutment stress distribution in the web pillars under different slope angles and mining depths,and established a relation describing the stress distribution in the web pillar.The relationship between the abutment stress and the ultimate strength of the web pillar under different pillar widths was also analyzed.In combination with the failure characteristics of the pillar yield zone,this relationship was used to explore the instability mechanism of web pillars.Finally,the optimal retaining widths of the web pillars were determined.Based on the modeling results,a mechanical bearing model of the web pillar was established and a cusp catastrophe model of pillar-overburden was constructed.Additionally,the web pillar instability criterion was derived.By analyzing the ultimate strength of the web pillars,a formula for calculating the yield zone width either side of the pillars was established.Using the instability criterion of web pillars in highwall mining,a reasonable pillar width can be deduced theoretically,providing significant guidance on the application of highwall mining technology.

榆神矿区西湾露天煤矿水文地质条件分析

西湾露天煤矿露天采区对开采影响较大的含水层为萨拉乌苏组孔隙潜水含水层、风化岩裂隙含水层及烧变岩孔洞裂隙含水层。通过对西湾露天煤矿水文地质条件的分析与探讨,指出威胁煤矿开采的主要水害因素,明确防治水工作重点,可科学可合理地进行煤矿防治水规划。

西湾露天煤矿首采区东端帮边坡稳定性分析

针对露天煤矿开采期间的边坡稳定性分析,开采领域的相关学者及技术人员进行了多方面的研究,并对露天煤矿边坡稳定性进行了判定及优化方案的设计。本文以西湾露天煤矿为研究对象,结合东端帮实际工程地质条件,建立了边坡稳定性计算模型,并基于Slide软件分别采用简化Bishop法、Janbu法与Fellenius条分法对东端帮边坡稳定性进行计算。结果表明,稳定系数分别为0.737、0.733、0.736,得出西湾露天煤矿东端帮上部由风化岩组层构成的台阶存在滑坡危险的结论,并提出了优化方案。具体方案为调整上部风化岩组台阶高度为9 m,台阶坡面角为60°,保安平盘宽度为6 m,最终端帮稳定系数达到1.2以上,为类似条件的露天煤矿提供了借鉴。