深部厚矿床崩落开采法的新发展

针对深厚矿床崩落开采法的问题,通过回顾深部矿床崩落开采法的新技术,提出改进的端部放矿分段崩落采矿法,在矿井能够从跨落的岩石下回收所有的矿石,具有最好的矿石回收参数,高开采强度,较有利的安全的工作条件。当开低、中品位的矿石时,采用控制顶板跨落的连续房式开采方法在经济和技术参数方面要好于基本的硬化充填法,并且在深矿床的复杂的地质力学条件下,能够保证采矿工作安全。

矿业行业向深部进军:地下硬岩开采技术的发展趋势

地下硬岩开采占全球采矿作业的40%,相比于露天矿山,地下矿山往往更有针对性,成本更高,且生产率更低。采用哪种地下开采方法主要取决于所开采矿床的地质情况。其中,回采法是最常见的一种开采方法,并且该方法的产量在总产量中的占比也是最高的,几乎达到50%;分块崩落开采法(Block Caving)是运用最少的采矿方法之一,但是在总产量中所占的份额却非常大,接近25%。同样地,这些地下采矿方法的应用通常也是由矿床和采矿的经济效益所决定的,因此在一定程度上,采用哪种采矿方法并不是矿山运营企业所能控制的。

无底柱分段崩落法开采顶板围岩崩落机理

以武钢程潮铁矿西区开采为工程背景,采用现场钻孔监测与相似材料模型实验相结合的方法,对无底柱分段崩落法开采过程中顶板围岩的变形和崩落规律进行了系统研究.首先,结合矿体赋存条件、地层结构和开采进程,设计两个钻孔实时监测顶板围岩的崩落规律.其次,以模型相似理论为基础,确定了所要研究模型的剖面和几何尺寸,设计制作模型,采用百分表、压力传感器和近景摄影测量等手段监测模型的应力、应变和破坏特征,并对百分表数据、应力盒数据、围岩位移和围岩破坏裂纹进行系统分析.研究成果初步揭示了金属矿山无底柱分段崩落法开采过程中,顶板围岩崩落机理和地表沉陷的基本规律.

Numerical Simulation of Independent Advance of Ore Breaking in the Non-pillar Sublevel Caving Method

The mechanism of stress generation and propagation by detonation loading in five separate independent ad-vance of ore breaking patterns is discussed in the paper. An elastic numerical model was developed using AN-SYS/LS-DYNA 3D Nonlinear Dynamic Finite Element Software. In this package ANSYS is the preprocessor and LS-DYNA is the postprocessor. Numerical models in the paper to actual were 1:10 and the element mesh was dissected in scanning mode utilizing the symmetry characteristics of the numerical model. Five different advance rates were stud-ied. Parameters,such as the time required to maximum stress,the action time of the available stress,the maximum ve-locity of the nodes,the stress penetration time,the magnitude of the stress peak and the time duration for high stress were numerically simulated. The 2.2 m advance appeared optimum from an analysis of the simulation results. The re-sults from numerical simulation have been validated by tests with physical models.

Similar material simulation of time series system for induced caving of roof in continuous mining under backfill

With the help of similar material simulation test,time series system for induced caving of roof in continuous mining under complex backfill in ore body No.92 of Tongkeng Tin Mine was studied. According to the similarity theory,a two-dimensional similar simulation test-bed was constructed. The stress and displacement that change along with the advance of mining were acquired and analyzed automatically by data system. The processes of continuous mining of ore-block in 5 intervals and artificial induced caving of roof were simulated. The results of the test show that ore body remained as safety roof in thickness of 15 m guarantees the safe advance of stoping work face. Caving of safety roof puts in practice at the first two mining intervals when the third interval of continuous mining is finished,and one interval as the safety distance should be kept all the time between stopping and caving. While mining in the last interval,pre-slotting should be implemented first of all,and the roof of the last two mining intervals is caved simultaneously. Only this kind of time series system can be an efficient and safe way for induced caving of roof in continuous mining.

Characteristics of Gas Emission at Super-Length Fully-Mechanized Top Coal Caving Face

Characteristics of gas emission at the K8206 working face in the Third mine of the Yangquan Coal Group were investigated. The effects of strata movement,advancing velocity of working face,production capacity of working face and gas extraction capability of strike high-level entry on gas emission at K8206 working face were analyzed. A regression equation,reflecting the relationship between relative gas emission rate and the production capacity of work-ing faces,was established. Another regression equation showing the relationship between the gas emission rate from adjacent layers when the working face was advancing for one metre and advancing velocity was derived. It can be con-cluded that,1) the amount of gas emitted at the K8206 working face is far greater than that of ordinary top coal caving faces with a dip length of 180-190 m; 2) the dynamic process of gas emission from adjacent layers during the initial mining stage is controlled by the movement of key strata; 3) the amount of gas emitted that needs to be forced out by air is greatly affected by the capability of gas extraction; 4) when the advancing velocity is between 3.5-5.5 m/d or when the output is up to 8-12 kt/d,the gas emission from adjacent layers is almost constant.

Patterns governing distribution of surrounding-rock stress and strata behaviors of fully-mechanized caving faces

By employing numerical modeling, similar material simulation and comprehen-sive field observation, investigations were made and patterns were obtained governing surrounding-rock stress distribution and strata behaviors. It shows that patterns governing displacement of FMC roadway surrounding rocks and those governing deformation of supports are basically the same along the strike, but the displacements vary greatly. The front stresses affect greater areas than the lateral stresses and their limit widths of equilib-rium zones and K are almost similar. The stress transmits very deep. Our findings offer scientific basis on which to determine parameters for coal pillar retaining and for roadway out-laying, thus increasing the recovery ratio and improving the maintenance of roadway.

Study on gob-side entry retaining technique with roadside packing in longwall top-coal caving technology

Pointed out some technical difficulties of gob-side entry retaining with roadside packing in longwall top-coal caving technology (LTCT), and analyzed the function mecha-nism of roadside filling body. Theory analysis shows the mechanical properties of high water material fit for the feature of deformation of gob-side entry retaining in LTCT, and gob-side entry retaining in LTCT face is one of effective ways to increase the recovery ra-tio of mining district.

Characteristics of ground behavior of fully mechanized caving faces in hard thick seams

It is showed in practice that the support load and its fluctuation is large, the periodic weighting is obvious and can be divided into two kinds, the large and small pressure, sometimes the behavior of the large pressure is very violent in hard thick seam caving faces. These are obviously different from those of the generally soft or medium hard seam caving feces. All above these are summarized, and the causes aroused these are researched. Finally the powered support selection of hard thick seam caving faces is discussed.

Comprehensive analysis of safe mining to heavy and steep coal seam under complex geophysics environment

In virtue of effect of N-S intensive ground stress and mining disturbance to +579E2EB_(1+2) mining site at Weihuliang Mine,the dip angle and section height is 65° and 52 m,respectively,the collapses happed frequently during mining.Firstly,mining condi- tions,spatial structure and parameters were investigated.Then physical simulation and dynamic numerical tracing and elaborate simulation relating roof and top-coal were ap- plied based on 2D-Block Program and quantitative regularity of stress at variable depths had been estimated.Furthermore,it was manifested that effective measures,i.e.,fast mining,control symmetrical top-coal-caving at dip and strike directions,optimizing ventila- tion system,active-stereo preventing gas were performed successfully in mining practice. Ultimately,the derived dynamic hazard were prevented so as to safety mining.

Simulation Analysis of Coal Mining with Top-Coal Caving Under Hard-and-Thick Strata

The top-coal falling ability is a key factor to analyze for the application of coal mining with top-coal caving. Based on a hard-and-thick strata,which acts both as the floor of the upper coal seam and as the roof of the lower coal seam, nine mining projects were put forward to examine the mining of upper and lower coal seams, and a numerical simulation was used to study in detail the corresponding top-coal compressed volume of the lower coal seam. By the simulation effects of different layouts of coalface, the rational mining method was determined to be the staggered layout of coalface in the upper and the lower coal seam. This can ensure the successful use of fully-mechanized coalface with top–coal caving in the lower coal seam.

Control on mine pressure of thick and strong roof stratum movement in long wall thick coal caving face

The caving of thick and strong roof stratum causes tremendous rock pressure in mine.The results of the analysis on dynamic natures of actual measurements of some fields,of which the roof pressure can be caused by thick and strong stratum in long wall thick coal caving face,could present the relation between the collapse and movement of thick and strong roof strata and surrounding rock pressure.In order to control the roof pressure effectively,the thick and strong roof strata,can be fractured and softened previ- ously by hydraulic fracturing and low-high pressure water infusion,fracturing and softening method.The results of study can provide basis for strata control and safe management in long wall thick coal caving face.

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.

Reliability analysis of the velocity matching of coal cutting and caving in fully mechanized top-coal caving face

The matching relationship between coal cutting and caving in fully mechanized top-coal caving face is analyzed in detail from the angle of reliability. The coupling equation of reliability is established correspondingly, and the mathematical equation of the coefficient of velocity matching of coal cutting and caving is obtained, which meets a certain reliability demand for making the working procedure of coal caving not influence coal cutting of coal-cutter. The results show that the relationship between the coefficient of the velocity matching and the reliability of coal cutting and caving system is linear on the whole when R <0.9. It is pointed out that different numerical value should be selected for different coal face according to different demand for reliability.

Arrangement of anchor reinforcement in roadway for fully mechanized sublevel caving

Bolting of mining roadway for fully mechanized sublevel caving has been practised successfully in Hebi mining area.It provides a new method for roadway support and settles the problem of support difficulty radically for sublevel caving in Hebi mining area.Where anchor reinforcement holds an important station in roadway support.This article brings forward the arrangement project of anchor based on theoretic analysis.Compared with arranged in the middle of the entry, anchor arranged in the vertex of the entry can reduces the length of anchor,shortens the anchor installation time,and heightens the reliability of anchor installation.

Deformation of mining caving zone grouting compound rock under overlying strata pressure

To solve the problem of surface subsidence caused by mining,the main method is to reasonably process coal mining space.'Mining caving zone high-pressure grouting pulverized coal ash hydromass controlling roof and overlying strata movement' technology is one of processing methods.After grouting pulverized coal ash hydromass in mining caving zone,formed one kind of special material which is used to support roof and effec- tively control the subsidence of overlying strata.For the accurate calculation of roof mining subsidence at grouting state,based on the characteristics of such materials,established its constitutive equation based on certain assumptions,gave deformation calculation method when the compound rock supports overlying strata,lay foundation for the actual calculation of subsidence of overlying strata after grouting and the promotion of mining caving zone grouting technology.

多放矿口条件下崩落矿岩流动特性

基于离散元理论和PFC3D程序构建放矿模型,探究多放矿口条件下崩落矿岩流动特性,实现多放矿口条件下放出体及矿石残留体形态变化过程的可视化.同时,将模拟结果与已有研究结论进行对比分析,验证基于PFC程序的放矿模型在崩落矿岩流动特性研究中的可靠性.放矿PFC模拟结果表明,多放矿口条件下放出体形态会因各放矿口间的相互影响而产生交错、缺失等程度的不同变异,并不是一个规则的椭球体.在单一放矿口和多放矿口条件下,放出体高度的变化趋势均可概括为两个阶段:在放矿初始阶段,放出体高度呈指数形式快速增加,随放矿量的增加,其增长率逐渐减小;随后,放出体高度将随放矿量的增加而呈线性增长的趋势.矿石损失率随放矿口尺寸及崩落矿石层高度的增大而减小,随放矿口间距的增大而增大.当相邻放矿口间产生相互影响时,平面放矿方式与立面放矿方式相比,其矿石残留量更小,且崩落矿岩接触面呈近似水平状态下降.