A conditional fractal (fBm) simulation approach for orebody modelling

Abstract

Fractal methods provide scale-invariant approaches to modelling the in-situ variability of orebody attributes. Fractional Brownian motion (fBm) models are a specific class of random fractals that offer a fast and efficient way to generate simulations of pertinent orebody characteristics. fBm models are constructed using the Weierstrass-Mandelbrodt equation and a fractal co-dimension inferred from the available data. Unconditional fBm simulations can be further constrained to existing data to generate conditional simulations reproducing the (i) available data, (ii) data statistics, and (iii) power law variogram and fractal co-dimension. The computational efficiency of the conditioning process is improved based on dual kriging. Testing conditional fBm simulation in a controlled environment indicates that it is an efficient approach to generating multiple realisations, when the available conditioning data is in the order of several hundred. The efficiency and performance of the approach suggest that it may be particularly suitable for delineating ore/waste boundaries and grade control.     

备战铁矿露天矿及与挂帮矿同时开采稳定性研究

备战铁矿是正在由露天转井下生产的大型铁矿,挂帮矿采用分段空场法回采,地下矿体拟采用无底柱分段崩落法回采。挂帮矿必须与露天矿同时开采,才能在地下开拓工程建成前完成回采任务并形成覆盖层。挂帮矿采用分段空场法回采,地表不可避免会产生连续移动和变形,进而影响露天边坡的稳定性。挂帮矿和露天矿同时生产的安全成为备战铁矿亟需解决的迫切问题。利用FLAC三维建模软件建立过渡期备战铁矿露天边坡与挂帮矿同时开采的的分析模拟平台模型,选择合理的采场尺寸并模拟挂帮矿开采对露天边坡安全稳定性的影响。经模拟结果表明分析,得出挂帮矿开采对露天边坡不会造成严重的露天边坡大面积拉伸破坏,在进行挂帮矿开采时露天边坡基本稳定。     

Stochastic modelling of the open pit to underground transition interface for gold mines

Criteria or transition indicators to guide the complex decision problem of open pit to underground (OP-UG) transition are currently not well defined and documented as most mines rely on context-dependent experiences of their respective project feasibility teams. This problem is further compounded by the fact that transition indicators such as net present value (NPV), stripping ratio and commodity price are dynamic over time. Therefore, traditional deterministic approaches to solving the OP-UG transition problem cannot fully address the practicalities that mining companies face due to the variability of the transition indicators. This paper therefore reviews the OP-UG transition decision problem from a stochastic perspective. Transition indicators identified from an extensive literature review were used to benchmark four case study mines against one which had recently made the OP-UG transition, subsequently leading to the development of a generic OP-UG transition model for gold mines. The model indicates that depending on the type of deposit, gold mines can prepare to transition when the gold price to cost per ounce ratio is just greater than 2.0; grade is between 4 and 9?g/t, stripping ratio is between 3 and 15?m³/t and NPV is positive for the underground mining option.     

Underground mine planning: stope layout optimisation under grade uncertainty using genetic algorithms

Stope layout optimisation finds a technically producible orebody portion that maximises the profit of the mining operation based on the stoping method used. A three-stage stochastic optimisation model combining genetic algorithms (GA) is proposed to account for grade uncertainty. The first stage computes the stope layout uncertainty, the second stage creates average design and their feasibility evaluation breeds the initial population, and the third stage uses GAs to improve this initial population over generations. The approach generates higher profit, less planned dilution, and a robust stope layout that is insensitive to orebody grade fluctuations.     

哈尔乌素露天矿边坡稳定性数值模拟分析

通过现场取样,实验室实验的方法计算出围岩的单轴抗压、抗拉强度、抗剪断、弹性模量、泊松比和容重,然后运用Sarma法对哈尔乌素露天矿边坡稳定性进行计算,计算出滑动安全系数为1.1,最终判断出哈尔乌素露天矿边坡的稳定性。     

Monitoring networks for open pit mines

ABSTRACT

Monitoring networks are used in open pit mines to ensure safety of men and equipment and avoid disruptions in the mining operation. The methodology applied to monitoring networks includes their design, selection of suitable instrumentation, control of systematic errors, and analysis of the observational data. In this paper it is proposed that the methodology suggested in Larocque (1977) be modified to give a more reliable determination of movement. A BASIC computer program suitable for a hand held computer, which enables one to detect statistically significant horizontal movement in the field, is also given.     

北衙露天转地下开采隔离矿柱的稳定性分析

露采边坡和隔离矿柱稳定性分析是露天转地下矿山经常面临的问题,对于金属矿山地下开采安全生产极其重要。根据北衙金矿矿段隔离矿柱的厚度以及边坡工程地质条件,采用有限差分法数值软件对露采转地下的隔离矿柱进行了不同厚度的模拟计算。结果表明,露采边坡在地下开采期间隔离矿柱设为50m较为可靠,边坡基本处于稳定状态,为该矿体安全高效回采提供了理论依据和技术指导。     

露天矿山开采境界动态优化圈定

按不同边界品位对矿床模型进行优化参数属性赋值,形成一系列静态价值模型,运用动锥法及L-G法进行初步优化,获得一系列静态境界方案,通过编排进度计划等方式将时间属性植入矿床块体模型,计算不同境界方案的年现金流,经贴现获得净现值(NPV),综合比较各方案NPV及资源回收情况确定最终方案。以某大型露天铜矿为例,利用矿业软件Surpac及进度计划软件Min-esched实现了最终境界的动态优化圈定,结果显示,原静态最优方案为不可行方案,而动态优化最终方案在经济效益上占绝对优势。     

Recent findings in open pit optimization

ABSTRACT

This paper reports on research in which pit designs using the Lerchs-Grossman and Moving Cone Algorithms were individually compared with those of the Dynamic Cone Algorithm. The comparisons wore on the basis of total final pit economic values. Details of the study are described and the results obtained discussed. The results showed that each algorithm in the pairs tested, gave several higher final pit economic values than the other. It is concluded that a correct approach to open pit optimization is to use several different algorithms and then select the beat valued pit from among the resulting designs.     

露天转地下矿山边坡挂帮矿开采数值模拟研究

利用ANSYS有限元大型数值模拟分析软件,通过建立某铁矿追脉开采露天高边坡三维数值模型,进行数值模拟计算,分析残采边坡的稳定性,得到结论:平硐追脉开采对某铁矿露天边坡整体稳定性影响不大,残采边坡是稳定的,但应加强平硐硐口和采空区顶板的支护和管理.     

露天矿山爆破质量优化措施

介绍了爆破过程中遇到的问题及改进措施.通过不断优化完善爆破施工规范,有效地保证了施工质量,提高了爆破效果.     

露天高边坡开挖预裂爆破技术

洛界高速公路No.4标段地处丘陵,附近有国家一级文物保护区龙门石窟.在复杂环境下进行路堑开挖爆破,对钻孔方向及角度的控制、不耦合装药、线装药密度及装药结构、微差起爆控制单响药量起爆网路等方面进行了全过程控制.有效降低了爆破震动对高陡边坡的伤害,保证了边坡成型和稳定以及被保护对象的绝对安全,取得了良好的爆破效果.     

露天矿分期开采联合运输的转载(上)

在总结国内外联合运输方式中转载经验的基础上，阐述了转载方式的分类、转载位置、转载能力，并提出了一些新的理论计算方法和公式     

大平掌铜矿露天采场滑坡体处置方法研究

开采过程中,大平掌铜矿露天采场东南部边坡顶部出现了局部裂缝,变形破坏范围大,程度深,局部出现了坍塌,给矿山安全生产造成了较大的隐患。通过对大平掌采场东南部露天滑坡体边坡的工程地质调查,确定造成滑坡的主要因素,提出3种处置方案。采用敏感分析法和正交试验设计,对采场东南部边坡稳定性进行了系统分析研究,并借助MicroMine软件对滑坡主轴方向所取剖面进行边坡岩土体参数反演分析,直观反映工程内部结构和分析结果。综合考虑本矿山所处地理位置、地震记录及矿山生产经营的需要,选出最优处置方案。采用最优方案进行处理后,大平掌矿东南部滑坡体得到有效控制。     

露天矿汽车斜坡提升系统

露天矿汽车斜坡提升系统，是一项低成本，效率高的新型装备与技术。从技术经济、安全等方面，阐述了在开采深度较大的露天矿运转系统中，利用该提升系统代替传统汽车一斜坡道运输系统是十分合理的。     

Truck dispatching in an open pit mine

Abstract

In an open pit mine operated by trucks and shovels, the trucks should be dispatched from the crusher to the shovels in such a way that the productivity of trucks and shovels in maximized while maintaining a rational production plan as well as obtaining target grades and other objectives with small variations at the entrance to the concentrator.

To solve the dispatching problem we present a three step approach. First we select shovel locations with a man-machine interactive system. This step combines operator expertise and linear programming optimisation. In the second step, we establish an optimal strategy (production plan) for a certain period of time by solving a network problem with non-linear costs associated with estimates of trucks' and shovels' waiting times and the quality objectives. The solution gives, for each shovel, the best access paths, the trucks' and shovels' estimated waiting times and an estimate of the number of trucks loaded per unit of time. In the last step we dispatch each truck in real-time by solving an assigment problem, taking into account the next 15 trucks, which are becoming available for dispatching in order to get a series of dispatches which will realize the optimal strategy.     

露天矿裂隙岩体边坡离散单元法模拟分析

离散单元法能够分析节理裂隙岩体沿离散界面产生滑移、张裂、垮落等大变形问题,是岩石开挖工程中分析非连续介质问题的重要方法。徐东沟露天矿最终境界边坡上下部均由坚硬块状结构岩体组成,而边坡中部则为岩性较软的绿泥石英片岩构成,且为典型的顺坡向层状结构,分析表明,绿泥石英片岩构成的局部边坡区域位移较大,模拟开采至最终-348m水平时,水平位移最大达1.6m,垂直向下位移达1.4m,应用强度折减法得到边坡安全系数仅为1.05,开采出露后极有可能产生边坡失稳,影响矿山的安全生产。     

晋陕蒙接壤区露天矿不同质地土壤水分运动特征与模拟

分析了晋陕蒙接壤区不同质地土壤水分运动规律,为构造一种理想的层状土体提供参考依据。设置沙土、砒砂岩、黄绵土和红黏土4种均质土柱,利用室内土柱自动观测系统测定4种矿区土壤入渗及蒸发过程,结合HYDRUS-1D模型反解土壤水力参数,并利用反解的参数模拟土壤的入渗与蒸发过程。通过湿润峰运移、入渗速率、累积入渗量评价土壤入渗性能,对比蒸发强度和移动能力评价土壤蒸发性能。研究结果表明,不同质地土壤入渗性能与蒸发性能差异较大,入渗性能从大到小排序为：沙土、砒砂岩、黄绵土、红黏土,蒸发性能从大到小排序为：黄绵土、红黏土、沙土、砒砂岩。4种土壤入渗过程模拟结果的Re（相对误差）绝对值都在11.0%以下,R2在0.90以上,沙土、黄绵土、红黏土蒸发过程模拟结果Re（相对误差）绝对值在6.1%以下,R2在0.94以上,砒砂岩因质地特殊,蒸发过程模拟结果Re（相对误差）绝对值为14.0%,R2仅为0.44,整体评价利用HYDRUS-1D结合入渗、蒸发过程剖面含水量变化反演土壤水力参数具有较高的精度。不同质地土壤水分运动特征的测定与模拟,对指导露天矿区排土场新土体构筑提供了参考。     

Short-term planning for open pit mines: a review

This review examines the current state-of-the-art in short-term planning for open-pit mines, with a granularity that spans days, weeks or months, and a horizon of less than one to two years. In the academic literature, the short-term planning problem for open-pit mines has not been as widely considered as that for the medium- and long-term horizons. We highlight the differences between short- and longer term planning in terms of both the level of detail to which a mine site is modelled, and the objectives that are optimised when making decisions. We summarise the range of techniques that have been developed for generating short-term plans, capturing both mathematical programming-based methods and heuristic approaches using local-search and decomposition. We identify key challenges and future directions in which to advance the state-of-the-art in short-term planning for open-pit mines.