露天矿陡帮开采工艺分析

在当今的岩矿露天开采作业中,陡帮开采是一项重要的工艺措施。为实现此项开采工艺的合理应用,本文特以福建省漳州市华安县水空矿区露天陡帮开采项目为例,对其露天开采过程中的陡帮开采工艺应用进行分析,包括凿岩设备选择、爆破技术应用、铲装技术应用以及防洪排水技术应用等。希望通过本次的分析,可以为陡帮开采工艺的应用与岩矿露天开采质量的提升提供一定参考。

岩石和矿物测试过程中基本方法及溶液的选择及误差研究

在开采岩石和矿物的过程中,岩石和矿物通常含有多种元素。如何测试和分析岩石和矿石中的元素,对于确定矿石类别、区分矿石类别和分析矿石成分具有重要意义。对于目前的岩石和矿物开采,有许多根据不同矿石类型进行测试和分析的方法。要取得积极的试验和分析结果,必须正确认识岩矿石的试验方法和分析,根据矿石类型正确选择试验和分析方法,提高岩矿分析效果,最大限度地提高岩矿测试分析效率,满足岩矿测试分析需求,有效开发岩矿资源,提高岩矿分选效果。因此,我们必须对岩石和矿物的测试和分析方法进行彻底的分析和讨论[1]。本文以岩石和矿物测试过程中的常用方法和常用溶液进行分析,在此基础上结合多年工作经验,着重对灰色误差理论在岩矿试验数据处理中的应用进行论证。经实际测试工作验证,灰色误差理论在岩矿试验数据处理中具有显著效果。

基于预先危险性分析法的大理岩矿安全评估分析

大理岩矿是国家经济和社会发展的重要物质资源,其开采时工程条件复杂,容易发生事故。文章基于预先危险性分析法,以某大理岩矿采区为对象,开展开采前的安全评估。经过危险因素辨识,对矿区按照边坡失稳、爆破伤害、高处坠落、车辆伤害事故分析危险性,最终确定综合危险等级为Ⅲ级,生产施工单位应引起重视。并针对每一项危险因素提出了相应措施降低危险等级,以提高岩矿开采的安全生产水平,降低事故发生的可能性。

无底柱分段崩落法在软破矿岩中以进路为单元组织生产的试验研究

本文论述了在软破矿岩中,为了克服采场分散、进路生产周期长而造成顶底板不稳固的弊端,试用以进路为单元的无底柱分段崩落的实质,以及回采工艺特点等。

关于矿山测试结果准确性的提升方法的探究

随着我国科学技术的不断发展,我国的岩矿开采事业也开启了新的篇章。在岩矿开采的过程当中,岩矿测试工作是必不可少的,在一定程度上,它可以有效地提高采矿的效率和质量。它也需要多种技术来支撑,专业性较强。所以在进行实际岩矿测试的过程当中,往往会存在一些问题,对采矿进程有一定的阻碍作用。相关工作人员通过实际研究,对岩矿种类进行合理的辨别,在不断的优化与改进当中,找到了合理的测试技术,保证岩矿元素在测试的时候能够更加准确。本文将对此做出详细介绍。

Numerical simulation of optimum mining design for high stress hard-rock deposit based on inducing fracturing mechanism

The 3D numerical simulation model of deep hard-rock deposit in Kaiyang Phosphate Mine of Guiyang was established based on the practical engineering using 3DEC numerical simulation software. The distribution characteristics of displacement fields and plastic zones of the orebody were simulated in three different excavation cases, including the case of excavation artificial inducted roadway in the orebody, the case of horizontal or vertical excavation direction and the case of the upward or downward excavation order. The simulation results indicate that the plastic zone and displacement field of surrounding rock around the inducted roadway are continuously increasing with the increase of the exposure time after digging an artificial inducted roadway in the orebody. Thus the raw rock ore becomes easier to be fragmented, which provides advantageous conditions for roadheader to cut high stress hard-rock. It is worthy noting that there is a large difference in effective utilization of deep ground pressure between horizontal and vertical excavation directions. The later can produce larger deformation and fracture zone than the former on the rock mass around the deduced roadway, which means that the later may utilize the high ground pressure more effectively to break hard-rock. And the obtained results also show that upward excavation order is more helpful for ground pressure to break rock than downward excavation order.

Non-explosive mining and waste utilization for achieving green mining in underground hard rock mine in China

Innovations of mining technologies were proposed by beneficial utilizations of unfavorable factors such as high geostress,high geotemperature and high mining depth to achieve green mining as mining depth increases inevitably.Cuttability of deep hard rock was investigated by experimental and regressed analyses to find the reasonable stress adjustment method to improve non-explosive mechanized fragmentation for hard ore-rock.A non-explosive mechanized and intellectualized mining method was proposed to continuously and precisely exploit phosphate underground,which promoted the high-recovery,low-waste and high-efficiency exploitation of phosphate with recovery rate over 90%,dilution rate near 5%and cutting efficiency about 107.7 t/h.A circular economy model and the backfill system were proposed to conduct resource utilizations of solid waste,by which the utilization amount of waste increased year after year.In 2018,the utilization amounts of phosphogypsum,yellow phosphorus slag and waste rock increased to 1853.6×10^3 t/a,291.1×10^3 t/a and 1493.8×10^3 t/a,respectively.

Fractal evolution mechanism of rock fracture in undersea metal mining

Through rock mechanics test, similar simulation experiment, borehole photographic observation of rock fissure, numerical simulation calculation of plastic zone distribution and deformation monitoring of rock mass during undersea mining, the fractal evolution mechanisms of rock fracture in undersea metallic deposits of Sanshandao Gold Mine were studied by fractal theory. The experimental researches on granite mechanics test in undersea deposit indicate that with the increase of load, the granite deformation energy and the fractal dimension of acoustic emission(FDAE) increase gradually. However, after reaching the peak stress of specimen, the fractal dimensions of acoustic emission(FDAEs) decrease and the granite specimen fails. Therefore, the fractal dimension evolution of rock failure can be divided into four stages, which are fissure inoculation stage, fissure growth stage, fissure expansion stage and fracture instability stage, respectively. By calculating and analyzing the damage photographs of rock specimens in Sanshandao Gold Mine, the fractal dimension of rock fissure is 1.4514, which is close to the average value of FDAE during granite destruction, i.e., 1.4693. Similar simulation experiments of undersea mining show that with the excavation proceeding, the FDAE in rock stratum increases gradually, and when the thickness of the isolation roof is less than 40 m, the FDAE begins to decrease, and meanwhile the sign of water inrush emerges. The numerical simulation researches on the plastic zone distribution of undersea mining in Sanshandao Gold Mine indicate that the fractal dimension of plastic zone(FDPZ) where the failure characteristics occur is 1.4598, close to the result of similar simulation experiment of 1.4364, which shows the sign of water inrush. Meanwhile, the thickness of the isolation roof for undersea mining should be more than 40 m, which is consistent with the results of similar simulation experiment. In Sanshandao Gold Mine, the rock fissures in undersea mining were observed by borehole photography and the rock mass deformation was monitored by multi-point displacement meters, and at the same time the fractal dimensions of strata borehole fissure distribution and energy release ratio(ERR) of rock mass were calculated by fractal principle, which are 1.2328 and 1.2685, respectively. The results demonstrate that rock deformation and fissure propagation are both in the second stage of fissure growth, and have not reached the fourth stage of fracture instability. Therefore, the conclusion can be obtained that the undersea mining in Sanshandao Gold Mine is safe at present.

Stability classification model of mine-lane surrounding rock based on distance discriminant analysis method

Based on the principle of Mahalanobis distance discriminant analysis (DDA) theory, a stability classification model for mine-lane surrounding rock was established, including six indexes of discriminant factors that reflect the engineering quality of surrounding rock: lane depth below surface, span of lane, ratio of directly top layer thickness to coal thickness, uniaxial comprehensive strength of surrounding rock, development degree coefficient of surrounding rock joint and range of broken surrounding rock zone. A DDA model was obtained through training 15 practical measuring samples. The re-substitution method was introduced to verify the stability of DDA model and the ratio of mis-discrimination is zero. The DDA model was used to discriminate 3 new samples and the results are identical with actual rock kind. Compared with the artificial neural network method and support vector mechanic method, the results show that this model has high prediction accuracy and can be used in practical engineering.

FUZZY MATHEMATICAL EVALUATION FOR MASONRY STRUCTURE BUILDINGS' DAMAGE GRADE CAUSED BY COAL MINING

Coal mining under buildings certainly causes surface movement and deformation, therefore, it brings about deformation even fracture for buildings. It is an important task to evaluate correcly the buildings’ damage grabe caused by coal mining. Fuzzy comprehensive evaluation,considering some factors of buildings’ fracture, has been applied to analyze the masonry structure buildings’ damage grade affer coal mining in this paper. It provides a scientific basis for buildings’reidercement before mining and maintenance or compensation after mining.

Protection Measures for Buildings Based on Coordinating Action Theory of Ground, Foundation and Structure

Based on the theory of coordinating action of building ground, foundation and structure, this paper presents a modified method for calculating additional stresses on buildings in mining areas by considering the joint effect of cur- vature deformation and horizontal deformation on buildings. It points out that for buildings over the coal pillar, it is ad- visable to soften the intermediate ground of buildings when they are affected by mining. For buildings over the goaf, it is preferable to soften the ground at both ends of buildings. In order to enhance the ability of a building to resist tensile deformation, the key measure is to reinforce the bottom foundation of the building. In addition, the concept of “angle of break of building” is proposed. It is because of this angle that the protecting coal pillar is left, which is a better solution than prevailing solutions The findings provide a more scientific basis for mining under buildings.

An assessment of coal pillar system stability criteria based on a mechanistic evaluation of the interaction between coal pillars and the overburden

Coal pillar design has historically assigned a factor of safety(Fo S) or stability factor(SF) according to their estimated strength and the assumed overburden load acting on them. Acceptable Fo S values have been assigned based on past mining experience or a statistical link between Fo S and probability of failure(Po F). Pillar width-to-height(w/h) ratio has long been established as having a material influence on both pillar strength and its potential failure mode. However, there has been significant disagreement on using both factor of safety(Fo S) and w/h as part of pillar system stability criterion, as compared to using Fo S in isolation. This paper will argue that there are valid technical reasons to bring w/h ratio into system stability criteria(other than its influence on pillar strength), as it is related to the post-failure stiffness of the pillar, as measured in situ, and its interaction with overburden stiffness. When overburden stiffness is also brought into pillar system stability considerations, two issues emerge. The first is the width-todepth(W/D) ratio of the panel and whether it is sub-critical or super-critical from a surface subsidence perspective. The second relates to a re-evaluation of pillar Fo S based on whether the pillar is in an elastic or non-elastic(i.e., post-yield) state in its as-designed condition, as this is relevant to maintaining overburden stiffness at the highest possible level. The significance of the model is the potential to maximise both reserve recovery and mining efficiencies without any discernible increase in geotechnical risk, particularly in thick seams and higher depth of cover mining situations. At a time when mining economics are, at best, marginal, removing potentially unnecessary design conservatism is of interest to all mine operators and is an important topic for discussion amongst the geotechnical community.

Field application of non-blasting mechanized mining using high-frequency impact hammer in deep hard rock mine

A non-blasting mechanized mining experiment was carried out with a high-frequency impact hammer,and the daily mining performance was recorded to explore the applicability of the high-frequency impact hammer in deep hard rock mines.Before the field application,the scope of the excavation damage zone was monitored,and rock samples were obtained from the ore body to be mined to carry out a series of laboratory experiments.Field application results show that the overall excavation efficiency reaches 50.6 t/h,and the efficiency of pillar excavation after excavating stress relief slot reaches 158.2 t/h.The results indicate that the non-blasting mechanized mining using high-frequency impact hammer has a good application in deep hard rock mines,and the stress relief slot is conducive to mechanical excavation.In addition,the high-frequency impact hammer also exhibits the advantages of high utilization rate of labor hours,small lumpiness of spalling ore,little dust,and little excavation damage.Finally,according to the field application and laboratory experiment results,a non-blasting mechanized mining method for hard rock mines based on high-frequency impact hammer is proposed.

Optimization of drilling and blasting operations in an open pit mine——the SOMAIR experience

Drilling and blasting play vital roles in opencast mining. These operations not only affect the cost of production directly but as well and significantly, the overall operational costs. This research was carried out to find a possible way of optimizing the drilling and blasting operations in an open pit mine of Somair (Société des Mines de l’Air), in the Niger Republic. In order to optimize the drilling operation, the time taken by two drilling machines to accomplish the same task was analyzed statistically. The result indicates that the Down the Hole Hammer Drilling Rig (DMNo406) is more efficient than the Drill Master (DM405). The relative unit consumption of two explosives (Explus and Nitram 9), when used under the same operating conditions, were also considered and the results indicate Explus to be more economical per unit consumption with a range of 0.15 g/t–0.183 g/t, when compared with Nitram 9 with a unit consumption range of 0.19 g/t-0.24 g/t in the study area.

Catastrophic destabilization of tunnel under rocks slipping in faultage

The model of catastrophic destabilization of tunnel under rock slipping in fault zone based on catastrophic theory and the potential function of fault movement were pre- sented.On the basis of the results above,through Taylor series expansion of the equation of equilibrium surface,its standard form was obtained.Analysis show that catastrophic destabilization of tunnel will occur only when stiffness ratio between elastic sector and strain weakening sector of soft rocks was larger than or equal to 1.On the other hand, sliding behavior and evolution path of fault were directly affected by exogenous process, and it was a major extraneous factor which leads to catastrophic destabilization of tunnel. In the condition of system catastrophe could be generated,if external forces vary from smaller to larger,firstly,fault sticks or creeps,and secondly,when external force equal to or larger than critical value,fault turns to slip suddenly.Inverse,if external forces vary from larger to smaller,fault smoothly slips firstly,when external force equal to or smaller than critical value,and fault turns to stick or creep suddenly.

Analytical and numerical method assessing the risk of sinkholes formation in mining areas

Voids, which have not been liquidated and associated with shallow mining excavations, pose a serious threat of potential formation of sinkholes. This threat is connected with the loss of stability of voids that had been formed as a result of mining operations in the deeper strata. Taking into account the impact of lower coal seams mining on shallow excavations and based on the example of a region that had been intensely exploited, this paper proposes a methodology for analysing the stability of shallow mine voids in the rock mass. Deformations in the excavation region were calculated by using FLAC2D computer pro- gram and assigning the Coulomb-Mohr model to the rock mass. Based on the numerical analysis, this paper evaluated the stability of the void in the event of a roof support fall. The results indicate the like- lihood of void formation. Based on the Budryk-Knotbe theory, the deformations of rock mass and sand- stone strata in the roof of the void, which had been caused by mining exploitation in consecutive years, were calculated. The results of numerical calculations and analyses were compared with the limit defor- mations values of sandstone in tension. It is concluded that the exploitations cause the void to break down. The proposed method can forecast the discontinuous deformations threats in the areas that have undergone shallow undermining exploitation and the areas of underground urban.

Mechanism of energy limit equilibrium of rock burst in coal mine

With the increase of mining depth,the effect of rock burst on coal mining is becoming more and more obvious and the rock burst mechanism becomes more and more complicated.Scholars from many countries had put forward different mechanisms,but no one gave a reasonable explanation to the mechanism of rock burst.In this paper,based on the energy theories,we studied the energy limit equilibrium（ELE） of coal mine rock burst The coal seam with rock burst is divided into energy limit equilibrium zone（ELEZ）（A） and elastic zone（B）;we also determined the position where the rock burst occurs,including the roof and floor of coal seams;in addition,we derived the limit width of ELEZ and the mathematic relationship between the limit width and occurrence mechanism of rock burst：the energy difference function（EDF）,w（x） = w_j - w_p,because first-order derivative w＇（x）,is less than 0.So EDF is a monotonically decreasing function.The graph of the energy difference function was also determined, through which we analysed the occurrence mechanism of rock burst.

SURFACE SUBSIDENCE ANALYSES BASED ON THE PRINCIPLE OF EXPANSION AND RECONSOLIDATION OF THE BROKEN ROCK STRATA

The results of experimentaI studies about the characteristics of broken rock expansion and reconsolidation were briefly introduced in this paper, and the surface subsidence coefficient under critical mining conditions was also analysed based on the principle of expansion and reconsolidation of the broken rock strata, a equation to calculate the corresponding surface subsidence was finally produced. This calculation method can be used to calculate more accurately the convergence quantity of consolidated rocks in the broken zone of the working face. In addition, case analyses by using the introduced calculation method were conducted and satisfactory results were obtained.

Effect of impulse and bedding on impact toughness of coal

In order to understand the properties of impact toughness of coal at different impact speeds,and the change of impact toughness of lump coal to joint directivity of lump coal,a series of impact tests were conducted on Beijing Da'anshan Lump Coal at different impact speeds and in different impact direction.Through analyzing the test result,it is shown that the change of testing samples is similar when impact is exerted on the vertical bedding and the parallel bedding when the impulse is less than 20 N.s,and the difference increases with the impulse increasing when the impulse is more than 20 N·s.At the same time,the expanding energy of fracture in samples increases with its expanding speed,and the expanding energy of fracture has close relation with the impact direction of the tested samples.And the difference of impact toughness of lump coal produced by different im- pact direction increase with the impact speed.The fracture surface of lump coal when im- pact is exerted on the vertical bedding is smooth and the broken block number is fewer; but the fracture surface of lump coal when impact is exerted on the parallel bedding isn't smooth and the broken block number is more,which inflects impact toughness of coal is sensitive to some deficiency.

Measurement of shear movements in the overburden strata ahead of longwall mining

An underground coal mine located in New South Wales has a target coal seam located 160-180 m deep directly below a 16-20 m thick conglomerate unit that has been associated with significant periodic weighting events on the Iongwall face. As part of the investigations to better understand the causes of periodic weighting at the mine. inclinometers capable of measuring horizontal shear movements through the full section of the overburden strata were installed ahead of mining at two locations approximately 1 km apart above the centre of two iongwall panels. These inclinometers were monitored as the longwall approached each site. This paper presents the details of the installation, the results of the inclinometer monitoring at both sites, and the insights that these measurements provide for overburden behaviour about longwall panels. Horizontal shear movements were observed to develop on shear horizons that correlate closely across the two sites suggesting a mechanism that is consistent across a large area of the mine. Shear movements were observed to develop on a single horizon near the top of the conglomerate strata that was mobilised almost immediately after initial formation of the longwall goal at a distance of 425 m ahead of the longwall face.