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1.
The presence of hard and massive sandstone above the coal seam in underground coal mines often leads to delay in caving of overlying rock beds thereby causing excessive load on supports and posing danger to underground workings. The problem is more prominent in blasting gallery (BG) as well as longwall mining methods in Indian coal mines. Induced caving by blasting is a promising means for hard roof management in underground coal mines. Based on extensive studies and data collected from different mines in India, a Blastability Index (BI) has been developed which can be used for the classification of roof according to the degree of ease in caving by induced blasting. Different charge factors have also been suggested based on the Blastability Index. Due to wide change in the method of extractions, ??Cavability Index?? for longwall panel was found ineffective in case of BG method of working as well as bord and pillar working. For this reason, this proposed Blastability Index would be of immense help for caving of hard roof by induced blasting. 相似文献
2.
无底柱分段崩落法采场稳定性分析 总被引：3，自引：0，他引：3
无底柱分段崩落法是国内外地下矿山广泛采用的采矿方法。长期以来由于受凿岩、装药以及出矿设备的制约,国内矿山大多采用小结构参数的无底柱分段崩落法,所产生的地压问题十分严重,开采效率低。近年来无底柱分段崩落法朝着增大采场结构参数的方向发展,不但有利于改善采场稳定性,同时还降低了生产成本。因此,开展采场稳定性分析有利于实现安全、高效开采。采用三维有限元方法对10 m×10 m、15 m×15 m、15 m×20 m共3种不同结构参数的崩落法采场进行了数值模拟,对进路开挖与矿石回采两个不同过程的巷道顶板竖直位移、主应力进行分析。数值计算结果表明：进路开挖时15 m× 20 m 与10 m×10 m的结构参数相比较,巷道顶板的竖直位移降低了20.1%,最小主应力下降了约18.8%;开采过程中顶板的竖直位移、主应力值都比进路开挖时小,采场地压得到改善;进路开挖与矿石回采过程巷道顶板的竖直位移和主应力值都随着结构参数的增大而降低。因此,大结构参数能更好地改善采场地压,增强采场稳定性,采用大结构参数的无底柱分段崩落法是安全可行的 相似文献
3.
顶板诱导崩落模式选择时变数值分析 总被引：2，自引：0，他引：2
顶板诱导崩落是一种新的空区处理技术,其实施效果与诱导崩落施工路径、方法和顺序有关,同时矿岩体作为一种弹塑性体,具有非线性时变力学特征。运用时变力学的基本理论,建立了顶板诱导崩落的时变力学有限元基本方程。针对大厂铜坑矿92号矿体试验采场的地质特征,构建了顶板诱导崩落的时变力学有限元模型,采用多步骤开挖模拟两种不同顶板诱导崩落模式,研究两种不同工序的顶板塑性区发展、东西预裂与崩顶硐室的位移及其安全系数,分析了其对采场的综合效应。结果表明,先预裂后崩顶的顶板诱导崩落模式有利于顶板崩落诱导,并综合考虑诱导崩落效果与作业安全,建议采用先预裂爆破后强制崩顶的微差爆破一次成型工艺。 相似文献
4.
In most mining operations the ore undergoes several processes such as drilling, blasting, loading, hauling, crushing, grinding and liberation to become the final salable product. Drilling and blasting is an important step in this process chain and it's results such as fragmentation, muckpile shape and looseness, dilution, damage and rock softening effect the efficiency of downstream processes. The value created per ton of broken ore is the difference between the price it commands when sold as the final product and the cost to produce it. Traditionally, the total process in the mining industry is classified into two groups as mining and milling. These are managed as separate cost centres inspite of the interdependency. Each process has a budget and production target and emphasis is usually on maximising production (tons) and minimising cost rather than the overall profitability of the whole business unit. The efficiency of each process is considered to be satisfactory as long as they are within budget and meet the production targets. The mine and mill managers usually try to optimise each process independently rather than the entire process. This paper discusses the potential pitfalls of decreasing the drilling and blasting cost per ton of broken rock without considering its impact on downstream processes. It introduces a holistic approach to blast optimisation by identifying and measuring the leverage that blast results have on different downstream processes and then optimising the blast design to achieve the results that maximise the overall profitability rather than just minimising the drilling and blasting costs. This paper demonstrates the benefits of such a holistic approach to blasting based on computer model simulations and field studies from metal and open cut coal mining. 相似文献
5.
针对金山店铁矿亟需确定的大断面结构参数问题,采用东北大学研制的SLS崩落放矿模拟系统和ITASCA公司的岩土工程软件FLAC3D,对该矿三期的采场结构参数进行了模拟分析和研究。数值放矿试验表明,崩矿步距对矿石回收指标影响较大,崩矿步距3.5～4.5 m更有利于指标回收,兼顾爆破参数因素时推荐为3.5 m。通过进路群开挖的数值模拟,并对开挖过程围岩的位移、应力和塑性区进行分析,发现开挖后塑性区范围不大,巷道具有良好的稳定性。因此,拟采用的进路参数从矿石回收指标和巷道稳定性方面看是较合理的方案。 相似文献
6.
C. Valdivia M. Vega C. R. Scherpenisse W. R. Adamson 《Fragblast: International Journal for Blasting and Fragmentation》2003,7(2):63-78
Vibrations due to production blasting can induce damage to the rock mass at large distances by altering larger geological structures, fault areas or other structures, where the orientation with respect to the mine geometry is unfavorable and can cause displacement of large rock volumes. Past occurrences of this nature in Escondida Mine placed geomechanical safety restrictions as to maximum allowable blast size in the northeast area of the mine. These restrictions limited the efficiency of drilling and blasting operations seriously limiting daily production. This is what prompted this study to attempt to increase shot size while reducing stability problems. This would permit keeping stable the slope over which the ore extraction belts are located, as well as the main access ramp to the mine. Using a rigorous and systematic instrumentation and monitoring effort of blasting vibrations at multiple locations with respect to an unstable location allowed the development of a database to establish acceptable vibrations limits. A parallel effort was the development and gauging of a mechanistic model for the prediction and simulation of blasting vibrations. Excellent results were obtained from a comparison between the measured and predicted results. This allowed the use of the gauged model to verify the practicality of increasing the shot size in the restricted blasting zones, without exceeding safe vibration limits. The practical success achieved using this research approach resulted in increased blasting size, with a consequent increase of blasted material per shot, and contributed to more flexible mining operations. 相似文献
7.
Because the land requisition and demolishing became difficult more and more, the mining scheme of Luohe iron mine was changed from caving method to filling method. In order to ensure the safety of the residence and the underground tunnel cavern within the mobile belt of the underground mining, the Luohe iron mine did the blasting test on the vertical crater retreat mining method and blasting vibration monitoring. The blasting experiments use common emulsified oil explosives and non-electric initiation system. The way of caved ore adopts the cutting groove and bench side. The NUBOX-6016 intelligent vibration monitor was chosen in the blasting vibration monitoring. Twice experiments on the blasting vibration monitoring were done on the surface or in the underground refuge cavern. The first test select the three monitoring points on the ground and the second select two monitoring points on the ground and a monitoring point in the underground refuge cavern. The blasting vibration monitoring data were conducted by the regression analysis in the Sodev’s empirical formula. The vibration attenuation formula about the underground blasting vibration transmitting in three directions is derived. The blasting test on the vertical crater retreat mining method and the blasting vibration were analyzed. It is estimated if the vibration damage possibly the surface buildings and related facilities of mine. 相似文献
8.
Blasting has been the most frequently used method for rock breakage since black powder was first used to fragment rocks, more than two hundred years ago. This paper is an attempt to reassess standard design techniques used in blasting by providing an alternative approach to blast design. The new approach has been termed asymmetric blasting. Based on providing real time rock recognition through the capacity of measurement while drilling (MWD) techniques, asymmetric blasting is an approach to deal with rock properties as they occur in nature, i.e., randomly and asymmetrically spatially distributed. It is well accepted that performance of basic mining operations, such as excavation and crushing rely on a broken rock mass which has been pre conditioned by the blast. By pre-conditioned we mean well fragmented, sufficiently loose and with adequate muckpile profile. These muckpile characteristics affect loading and hauling [1]. The influence of blasting does not end there. Under the Mine to Mill paradigm, blasting has a significant leverage on downstream operations such as crushing and milling. There is a body of evidence that blasting affects mineral liberation [2]. Thus, the importance of blasting has increased from simply fragmenting and loosing the rock mass, to a broader role that encompasses many aspects of mining, which affects the cost of the end product. A new approach is proposed in this paper which facilitates this trend 'to treat non-homogeneous media (rock mass) in a non-homogeneous manner (an asymmetrical pattern) in order to achieve an optimal result (in terms of muckpile size distribution).' It is postulated there are no logical reasons (besides the current lack of means to infer rock mass properties in the blind zones of the bench and onsite precedents) for drilling a regular blast pattern over a rock mass that is inherently heterogeneous. Real and theoretical examples of such a method are presented. 相似文献
9.
复杂地质条件下开采深度的增加极易导致强矿压动力灾害的发生。以华煤集团华亭煤矿250102综放工作面及其回采巷道为研究背景,通过SOS微震监测系统拾取回采工作面推进过程中微震(声发射)信号,获取强矿压动力灾害前兆信息特征规律,分析3种不同危险等级(R,O,Y)强矿压的分布规律且判定其危险区域。综合现场开采特征,确定工作面开切眼至400 m范围为危险区域,此期间20 m煤柱侧强矿压显现尤为严重。最终确定了采用"超前顶板深孔爆破+帮侧煤体卸压爆破+顶板煤层注水"相结合的解危措施来减轻和消除强矿压动力灾害现象,保障井下工作人员在工作期间的安全。 相似文献
10.
Arvind K. Mishra 《Journal of the Geological Society of India》2013,81(3):429-435
Ever since development of human civilization, mining and agriculture has been the backbone of growth. Today the most developed countries of the world are the ones focused on core economical development, be it power generation, steel making, oil and gas production, or agriculture. Mining has been gaining importance over the years both from the economic perspective and as an area of sustained research. With the advent of globalization, things have changed very fast and today it is an industry that is driving the economies of several nations. Global competition has propelled countries to reach higher production levels through better techniques of drilling and blasting, excavation and mineral processing. We now have bigger and faster drill machines and excavators. In Explosives technology too significant progress has been made towards having safer explosives and accurate initiating systems that have increased overall control over blasting in terms of vibration, fragmentation, throw, fly rock and overall blast economics. Explosives and Rock Blasting Technology has advanced so much in the last few decades that blasting can now be precisely performed, controlled and predicted. Development of new tools like electronic blasting systems and advanced simulation software has made it possible to customize blasting results as per requirement. These developments have helped mining engineer worldwide in reaping huge productivity benefits besides making it possible to meet the environmental norms even in most demanding conditions. Inability to blast large size shots on account of proximity of mines to human habitation have always constrained mine management in fully leveraging the strength of large size production equipments. Mine managers have been forced to conduct small blasts on increased frequency to provide feed to large capacity shovels while compromising on Shovel productivity on account of undesirable movement of shovels during blasting. This paper deals with a case study at SEB quarry of Tata Steel wherein it was difficult to fire a big blast due to existing nearby structures. A critical scientific study was conducted before successfully firing of one of the biggest shot of 83 tonnes in the history of quarry. The paper discusses the issues being faced, alternate solutions opted and the final outcome. 相似文献
11.
C. M. Wai D. E. Reece B. D. Trexler D. R. Ralston R. E. Williams 《Environmental Geology》1980,3(3):159-162
The Bunker Hill Mine in Idaho's Coeur d'Alene mining district produces approximately 10 m3/minute of acid water containing high concentrations of heavy metals. Field and laboratory studies indicate that much of the
acid water is produced in a single ore body in the upper part of the mine. The ore of this body contains mainly sphalerite,
galena, and pyrite in a siderite-quartz gangue. Ground water recharges this ore body through a near-vertical zone of high
permeability, which is the result of mining by the caving technique. Ore samples from the caving area contained oxidized forms
of iron and produced acid in a laboratory leaching test. Leaching experiments with several ore samples from the mine also
indicated that the ratio of pyrite to calcite in the samples strongly controlled the resultant pH values. Oxidation of pyrite
to sulfuric acid and compounds of iron is apparently responsible for the production of acid water in the mine. In contrast,
dissolution of calcite in water results in a basic solution, with pH around 8.3, that can neutralize the acid produced by
the oxidation process. Methods for prevention of acid mine drainage in this and other similar mines are noted. 相似文献
12.
Z. X. Zhang T. Naarttij rvi 《Fragblast: International Journal for Blasting and Fragmentation》2005,9(2):61-78
Due to the large-scale sub-level caving in Malmberget mine and the short distance between the mine and Malmberget town, the ground vibrations in the town have reached a high level since the year 2001 when large scale caving mining started. In order to control and reduce the high vibrations, LKAB launched a research project on active reduction of vibrations in Malmberget by using the wave interference or wave superposition method with electronic detonators. By means of this method, the vertical vibrations were reduced by 10% and the total vibration time for a ring blast was reduced by 80% according to five ring tests in the mine. For a further reduction of the vibrations, a second method, named changing initiation sequence in ring blasts, was developed on the basis of stress wave theory and the geographic conditions of the town and the mine. The second method has so far been applied in all of the drifts near the town, and the vibrations measured at the town show that the vertical vibrations caused by production blasts in the mine have been reduced by more than 31% on average. In addition, a third method, dividing a ring into two parts during blasting, was developed and used to reduce the ground vibrations from a number of very large rings in the mine. The results indicate that the vibrations have been reduced by more than 33%, and a more interesting and surprising result is that ore extraction has been increased by the third method. 相似文献
13.
Tong Zhao Changyou Liu Kaan Yetilmezsoy Baisheng Zhang Shuai Zhang 《Environmental Earth Sciences》2017,76(21):751
The thick hard rock (THR) roof of the long-wall mining face is prone to the large-sized cantilever roof, and its sudden fracture will cause serious rock dynamic disasters, such as coal and gas outburst and rockburst. In this study, based on the long beam theory, the initial fracture mechanical model for THR was established, and the first weighting characteristics and extreme fracture step distance were calculated. This study introduced a new technology called deep-hole pre-splitting blasting (DPB) which could break the THR by drilling holes with different depths and angles at different levels of roof rock and then blasting it. Field measurement analysis indicated that the immediate roof and lower thick hard strata were fully collapsed to fill the goaf, and the upper thick hard stratum was effectively cut off. The results showed that mechanical model and drilling holes method and DPB technique were so notably that would lead to a foundation for large-scale popularization and application in a Chinese Mine. 相似文献
14.
江西永平铜矿深部勘探设计探讨 总被引：1，自引：0，他引：1
矿床地质研究是详勘设计的基础,露采期间探采对比和钻孔稀密验证初步成果,表明Ⅱ矿带勘探网度可适当放稀,运用综合井中物探手段有可能节省钻探工程量,宜分期分段探矿,提倡探采结合及推广坑内钻探,尽量减少不必要的和过于超前的地表钻探投入 相似文献
15.
基于连续采矿的顶板诱导崩落技术,采用预裂爆破控制裂隙发展区间,强制崩顶爆破诱导顶板围岩裂隙发育、扩展,从而诱导顶板致裂失稳的可控崩落。然而在地下采空区顶板诱导致裂失稳崩落处理采空区过程中,预裂与崩顶爆破效果具有极大的隐蔽性,难以进行直观可视的评价。采用钻孔摄像系统,利用前视与全景可视技术,对顶板诱导爆破前钻孔形态和爆破的效果进行了探测,特别在爆破后的全景钻孔摄像,数字化描述了钻孔的裂隙特征,并通过钻孔摄像的图片分析评价了顶板诱导崩落爆破效果。全景探测的结果表明：（1）预裂爆破在顶板岩体中形成了清晰可见宽为20～40 mm的预裂缝,炮孔底部存在半个孔壁的预裂特征。（2）顶板围岩中产生了大量的次生诱导微裂隙带,裂隙交错呈“X”型,并且原生裂隙得到了扩展。（3）顶板诱导爆破实施后爆堆形状良好,大量裂隙发育以及碎裂岩体结构的形成有利于顶板的诱导可控崩落。 相似文献
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17.
Empirical approaches for predicting fragmentation from blasting continue to play a significant role in the mining industry in spite of a number of inherent limitations associated with such methods. These methods can be successfully applied provided the users understand or recognize their limitations. Arguably, the most successful empirical based fragmentation models have been those applicable to surface blasting (e.g., Kuz-Ram/Kuznetsov based models). With widespread adoption of fragmentation assessment technologies in underground operations, an opportunity has arisen to extend and further develop these type approaches to underground production blasting.
This paper discusses the development of a new fragmentation modelling framework for underground ring blasting applications. The approach is based on the back-analysis of geotechnical, blasting and fragmentation data gathered at the Ridgeway sub level caving (SLC) operation in conjunction with experiences from a number of surface blasting operations.
The basis of the model are, relating a peak particle velocity (PPV) breakage threshold to a breakage uniformity index; modelling of the coarse end of the size distribution with the Rosin-Rammler distribution; and modelling the generation of fines with a newly developed approach that allows the prediction of the volume of crushing around blastholes.
Preliminary validations of the proposed model have shown encouraging results. Further testing and validation of the proposed model framework continues and the approach is currently being incorporated into an underground blast design and analysis software to facilitate its application. 相似文献
This paper discusses the development of a new fragmentation modelling framework for underground ring blasting applications. The approach is based on the back-analysis of geotechnical, blasting and fragmentation data gathered at the Ridgeway sub level caving (SLC) operation in conjunction with experiences from a number of surface blasting operations.
The basis of the model are, relating a peak particle velocity (PPV) breakage threshold to a breakage uniformity index; modelling of the coarse end of the size distribution with the Rosin-Rammler distribution; and modelling the generation of fines with a newly developed approach that allows the prediction of the volume of crushing around blastholes.
Preliminary validations of the proposed model have shown encouraging results. Further testing and validation of the proposed model framework continues and the approach is currently being incorporated into an underground blast design and analysis software to facilitate its application. 相似文献
18.
安徽泥河铁矿矿区水文地质条件较复杂,矿体埋深大,在综合分析矿区水文地质条件、地表水、地下水相互水力联系的基础上,从岩层性质、地下水赋存及补给条件,确定了影响矿床充水的各因素,结果可知:泥河铁矿矿体埋藏深度大,顶底板围岩为隔水层,次生石英岩含水层为矿坑充水的主要间接补给源,其多位于矿体顶板之上50 m,受矿体上部导水性极弱的闪长玢岩层的限制,补给量微弱,对矿区大部分矿坑充水影响不大。但在矿区东北部和中部地段,受开采时冒落带以及导水裂隙带的影响,对该区域矿坑充水的影响较大。此次研究填补了该矿区深层地下水含水系统研究的空白,为准确预测矿坑涌水量提供理论依据,具有重要的参考价值和现实意义。 相似文献
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20.
符山铁矿四矿体采用无底柱分段崩落法回采,近年来相继发生四次大面积地压活动。本文介绍了采用岩体声发射监测仪、收敛计等多种手段,探索地压显现规律。在此基础上,相应地采用斜线回采工作线,改善联巷受力条件等地压控制措施及适当的巷道支护方式,使矿山地压活动得到了控制,实现了有计划地连续性生产,采场矿石回采率达82%以上。 相似文献