共查询到20条相似文献，搜索用时 31 毫秒
1.
P. S. N. Murthy 《Mathematical Geology》1989,21(4):443-461
This paper presents the results of disjunctive kriging applied to a supergene iron ore deposit of Bailadila Range of India. Disjunctive kriging is applied firstly to compare estimates of the blocks by ordinary kriging and secondly to estimate benchwise local recoverable reserves of the orebody. Good agreement exists between block estimates by ordinary kriging and disjunctive kriging except for peripheral blocks with less borehole information. Estimation of benchwise reserves shows that the behavior of the distribution of grades is different in various benches. The study shows that disjunctive kriging can be applied successfully for estimation of local recoverable reserves in the case of a good grade hematite iron ore deposit. 相似文献
2.
Roland Froidevaux 《Mathematical Geology》1984,16(4):327-350
One of the tasks routinely carried out by geostatisticians is the evaluation of global mining reserves corresponding to a given cutoff grade and size of selective mining units. A long with these recovery figures, the geostatistician generally provides an assessment of the global estimation variance, which represents the precision of the overall average grade estimate, when no cutoff is applied. Such a global estimation variance is of limited interest for evaluating mining projects; what is required is the reliability of the estimate of recovered reserves or, in other words, the conditional estimation variance. Unfortunately, classical linear geostatistical methods fail to provide an easy way to estimate this variance. Through the use of simulated deposits (representing various types of regionalization)the present paper reviews and discusses the effects of changes in cutoff grade and selective mining unit size on the conditional estimation variance. It is shown that, when the cutoff grade is applied to a pointsupport (sample-size)distribution, the conditional estimation variance appears to be readily accessible by classical formulas, once the conditional semivariogram is known. However, the evaluation of the conditional estimation variance seems to be less straightforward for the general case when a cutoff is applied to the average grade distribution of selective mining units. Empirical approximation formulas for the conditional estimation variance are tentatively proposed, and their performance in the case of the simulated deposits is shown. The limitations of these approximations are discussed, and possible ways of formalizing the problem suggested. 相似文献
3.
克里格法在离子吸附型稀土矿勘查储量估算中的应用 总被引：1，自引：1，他引：0
我国在离子吸附型稀土矿勘查工作中,一般采用地质块段法估算储量,块段法是将矿体划分为不同厚度的块段投影到水平或垂直方向上,块段的划分、各块段的面积和厚度、品位都会影响储量估算结果。本文以赣南某离子吸附型稀土矿床作为研究对象,基于先期勘探钻孔数据资料,运用三维建模软件创建了该矿床钻孔数据库,建立了矿区内矿体的三维DTM模型;采用克里格法对矿体进行稀土氧化物品位分析,将克里格法的储量计算结果与块段法的储量计算结果作对比分析。结果显示,克里格法计算的矿体体积比块段法增加了11.8%,稀土氧化物储量增加了15%,与实际勘探数据相比较,克里格法的计算结果基本合理,且具有快速、准确、方便的特点。本文利用自主开发的以克里格法为基础的三维数字矿山经济评价系统中价格-边界品位敏感性分析模块,动态设置边界品位,灵活圈定不同价格下经济可采的矿体边界,如当精矿的市场价格从10万元/吨变化为12万元/吨时,通过计算获得了此矿山经济可采矿体的空间扩展范围。基于克里格法的三维估算系统能够帮助矿山选择合理的采矿工程布置,有利于满足矿山动态管理的需要以及保证矿产资源的合理利用。 相似文献
4.
Forecasting of recoverable reserves aims to predict the tonnages and grades that will be recovered at the time of mining. The main concern in this forecasting is the imprecision in the selection of ore/waste resulting from both the so-called information effect or information that becomes available during grade control, and the support effect or mining selectivity during mining. Existing approaches to recoverable reserve estimation account for mining selectivity; however, they largely ignore the information effects from future data becoming available through grade control practices. An application at the Morila gold deposit, Mali, is utilized in this paper to document a new simulation-based approach for recoverable reserve forecasting that incorporates the potential effects of future grade control data. This accounts for the information effect as well as changes in data quantity and quality over time. In addition, the case study at the Morila mine elucidates the use of a newer, very efficient, and practical alternative to traditional simulation techniques. This direct block simulation method forecasts recoverable reserves directly into the selective mining unit (support) size under consideration. The case study demonstrates the practical uncertainty assessment of the recoverable reserves within the deposit, so that expected inaccuracies in the selection of ore /waste can be accounted for. This allows for fully informed mining decisions to be made that incorporate the effects of information and selectivity while quantifying the potential impact of uncertainty on the mine operation and its final economic outcome. 相似文献
5.
Geostatistical estimation techniques were customized to allow forecasting of production figures at the Silver Bell uranium mine (Uravan District).Surface drill hole data were used to provide a block model of kriged estimators of average uranium grades. Figures for recoverable ore grade and the ore-waste ratio are then deduced from regressive curves previously obtained from underground information and production data. Cross-validations of the entire model were performed and were found positive. 相似文献
6.
Models for Support and Information Effects: A Comparative Study 总被引：1，自引：0，他引：1
The recoverable reserves in an ore deposit depend on several factors, in particular the size of the selective mining units (support effect) and the misclassifications when sending these units to mill or dump according to their estimated grade (information effect). Both effects imply a loss of selectivity and have to be correctly forecasted. In this work, several models are reviewed and applied to a synthetic ore deposit characterized by a highly skewed grade histogram and a spatial connectivity of high grades. The affine correction, mosaic correction, and discrete Gaussian model are compared when assessing the global recoverable reserves, whereas local estimations are performed by indicator kriging with affine correction, bigaussian disjunctive kriging, and multigaussian conditional expectation. Despite their convenience and simplicity, distribution-free methods like affine correction or indicator kriging have a poorer accuracy than the other methods. In the global framework, the discrete Gaussian model is a better alternative and is based on mild assumptions. Local estimations are not accurate and may be improved by resorting to a more suitable parametric model or to conditional simulations. 相似文献
7.
敦煌金滩子金矿床系20世纪70年代初,在区调工作中检查古代采矿遗迹时发现,80年代开展过普查,经2014~2015年详查提交的一处中型金矿床。矿区由梭子山、八卦图和金滩子3个矿段组成。金矿化受断裂破碎带控制,加里东晚期石英闪长岩为八卦图和金滩子矿段石英脉型金矿的赋矿岩石,华力西中期二长花岗岩为梭子山矿段蚀变岩型金矿的赋矿岩石。目前控制主矿体长151~320 m、斜深155~350 m、矿体平均品位7.61×10~(-6)~17.94×10~(-6),矿体延伸较稳定,金品位较高。黄铁矿、褐铁矿、石英、方解石为主要载体矿物。据对金滩子金矿各矿段深部矿化特点及走向上控矿因素的分析,认为该矿床具有较好的找矿前景。 相似文献
8.
随着国内煤层气勘探开发技术的逐渐成熟,国内油气公司开始着眼海外煤层气资源勘探开发。但由于国外煤层气盆地资料匮乏,有效评价其可采资源量是一个难题。选取国外几个典型煤层气盆地,将地质类比法引入煤层气可采资源量估算中。结合煤层气富集成藏的基本要素,依据煤层气盆地实际资料,优选了影响煤层气可采性的10个地质参数作为刻度区和预测区的相似系数,二态定性量化不同地质参数。以等温吸附法确定刻度区的采收率,结合实际采收率经验,采用蒙特卡洛组合抽样估算了可采系数的变化范围。通过对北美、俄乌哈和澳大利亚3个地区10个煤层气盆地的可采资源量计算和对比,发现澳大利亚的鲍恩盆地煤层气可采系数大,可采资源量丰富,具良好的勘探开发潜力。该方法可为国外其他煤层气盆地的可采资源量计算提供借鉴。 相似文献
9.
B. K. Verma 《Mathematical Geology》1972,4(1):25-34
The Kolar Gold Fields are some of the best known gold deposits in India. An example of ore valuation utilizing 49 ore blocks of the Oriental lode of the West Reefs, explored and developed in the Nundydroog mines, is given. In this reef system, there are large ore reserves of sulfidebearing quartz reefs, and the gold distribution is erratic both along strike and downdip. Ore valuation at present is based on the arithmetic mean of samples taken at peripheral positions of the blocks. Samples taken from internal portions of the blocks give a totally different picture of the value. To correct this discrepancy, normal regression and lognormal regression of internal block and total block values, over peripheral block values have been used to evaluate the deposits. The valuation efficiency criterion shows the logarithmic variance for distribution of ratios of unregressed and regressed block values with the corresponding arithmetic mean of internal stope values as observed inside the blocks. The studies have shown that the logarithmic variance is minimum if the logarithmic regression is used, thereby indicating maximum efficiency. Further, the undervaluation and overvaluation of low- and high-grade blocks is less for the logarithmic example. With help of the logarithmic regression equation an effective pay limit of 177.8 in.-dwt has been found for selective mining, for peripheral block values corresponding to the official pay limit of 240 in.-dwt.NGRI contribution number 71-281. 相似文献
10.
《International Geology Review》2012,54(11):1450-1456
Early ideas of rapid decrease in ore in grade and reserves with depth has led to considerable pessimism on calculation of C2 reserves. Increased efficiency of mining methods, technology, and equipment has made it possible to mine many of the larger low grade deposits, lower grade deposits, and lower grade fringe deposits thereby greatly increasing the life of mines and mining districts. Most old mining districts have had productive lives far beyond known reserves at any one time. Ore zoning, except for unusual type of deposits, only rarely is of much practical importance in considering the depths of deposits. Geologic ore reserves of the C2 category have been greatly underestimated in Russia. This category is not used for planning the immediate development of deposits and as a result there are many errors of planning and development. C2 reserves should be calculated much more realistically than the present conservative practice and the results should be used in the proper economic development of ore deposits. - - J. A. Redden. 相似文献
11.
Marat. Z. Abzalov 《Mathematical Geology》2006,38(4):393-411
Recoverable mineralisation at a given mining selectivity is traditionally modelled from sparse data grids by non-linear geostatistical techniques such as Uniform Conditioning. This method estimates the tonnage and grade of mineralisation which can be extracted as small selective minable blocks from large blocks (panels), whose grade is modelled by Ordinary Kriging. Uniform Conditioning technique estimates the proportions of recoverable mineralisation in each panel without specifying the actual locations of the economically extractable blocks. This inability to predict a spatial location of the recoverable mineralisation is a major disadvantage of the conventional Uniform Conditioning method. A new approach, called Localised Uniform Conditioning, has been developed to overcome this limitation. This method applies the grade–tonnage relationships modelled by the Uniform Conditioning technique to the spatial grade distribution patterns approximated by direct kriging of the small blocks from the sparse data grid. This approach estimates localised selective mining units grades conforming to the proper grade–tonnage curves obtained by the Uniform Conditioning method as well as maintaining the relative spatial grade distribution pattern indicated by the directly kriged small block grades. The advantage of this approach is essentially dependent upon the data available for ranking the small blocks within a panel in increasing order of their grade. Ordinary Kriging of the small blocks can be used for their ranking providing the kriged estimates produce a meaningful indication of the relative grade pattern. Where the data is sparse and not close to a panel, or their distribution is characterised by a strong short-range variability, the advantages of using the Localised Uniform Conditioning approach are more limited. 相似文献
12.
13.
In open pit mining, cutoff grade is one of the most important factors in production planning, which is simply defined as a grade that discriminates between ore and waste. It is also a sensitive parameter can have a major impact on the net present value and cash flow of the projects. On the other hand, dilution is one of the most important and sensitive parameters in the mining projects, which is closely related to the cutoff grade. Choosing the optimum cutoff grade is of considerable importance, since it has a significant impact on the mining operations. One of the most popular algorithms for determination of the optimum cutoff grade is the Lane’s algorithm. But in the Lane’s algorithm, mining dilution and its cost is not considered during the cutoff grade optimization. In this paper, effects of dilution on the cutoff grade are studied using Lane’s theory. Dilution and its cost is inserted directly into cutoff grade optimization process. The cutoff grades obtained using suggested method will be more realistic rather than ones by using the original form of the Lane’s formulation. Results of the study showed that with an increase of dilution, average grade decreases and consequently the cutoff grade increases. As a result of dilution, the quantity Q m increases and the quantities Q c and Q r decrease. Therefore, the annual profit and NPV of project is very significantly reduced. 相似文献
14.
天津地区属于典型的中低温沉积盆地型地热区,地热资源丰富,现已被广泛地应用于地热供暖、生活用水、温泉洗浴等各个方面,取得了显著的社会经济效益。雾迷山组地热资源在天津地区分布广泛,是天津地区最主要的开采层之一。本文通过收集截至2015年底150眼雾迷山组地热井的数据资料,计算得出区内雾迷山组热储在回灌条件下地热资源可采量为14.108×10~8 m~3,地热流体可采热量47.021×10~(16) J/a,折合标准煤1 604.814×10~4 t/a,并对雾迷山组热储层的地热流体热量开采系数、最大水位降速和地热流体热量潜力模数三个指标综合考虑,确定地热资源开发利用潜力,可为今后雾迷山组地热流体的勘查和开发利用提供参考。 相似文献
15.
16.
The Arsen’evskoe deposit with large tin reserves is traditionally considered as a reference object of the Kavalerovo ore district. New data obtained allow us to draw genetic conclusions. It is shown that the deposit combines the products of three tin-bearing stages and final tungsten mineralization. Ores of different stages related to different magmatic complexes represent tin-sulfide, cassiterite-sulfide-silicate, and cassiterite-quartz formations and are complex in composition (Sn, Pb, Zn, Cu, Ag). Large volumes of multimetal ores of the Arsen’evskoe deposit are prepared for mining; their reserves can be doubled at minor additional costs. The inferred reserves of complex ores of the Arsen’evskoe and other ore fields of the Kavalerovo district are an order of magnitude higher than the known reserves and are large enough for highly profitable mining production. 相似文献
17.
Kateri Guertin 《Mathematical Geology》1987,19(5):407-423
A nonlinear correction functionK(Z*) is proposed to transform any initial linear grade estimatorZ* into a conditional unbiased estimatorZ**=K(Z*) with reduced conditional estimation variance. Such a corrected estimator allows more accurate prediction of ore reserves at any level of selection performed during the mine lifetime. The correction is based upon an analytical or isofactorial representation of a bivariate distribution model of true gradeZ and its estimatorZ*. This correction model allows derivation of conditional estimation variances for both estimatorsZ* andZ** and provides a solution to the problem of change of support. A case study is presented and performance of the proposed correction model is evaluated in terms of actual conditional bias and mean squared errors. Results obtained stress the practical importance of the correction model in selective mining operations. 相似文献
18.
Rafael Prez-Lpez Antonio M. lvarez-Valero Jos Miguel Nieto Reinaldo Sez Joo X. Matos 《Applied Geochemistry》2008,23(12):3452-3463
São Domingos is one of the most emblematic Portuguese mining districts in the Iberian Pyrite Belt (IPB). The beginning of mining exploitation in the area has been dated back to pre-Roman times, remaining in activity until 1966 when it was definitely halted. The intense mining labours are reflected in the presence of a huge amount of sulphide-mining wastes and downstream production of acid mine drainage (AMD). The mining wastes in the area are highly heterogeneous, and numerous different types may be recognized, including slags, iron oxides, smelting ashes, brittle and blocks of pyrite, leaching tank refuses, industrial landfill and other residues coming from ore extraction (gossan wastes and country rocks). The chemical speciation of potentially toxic elements (As, Cd, Cr, Cu, Fe, Mn, Pb, S, Sb and Zn) in all mine wastes from São Domingos was determined by modified BCR-sequential extraction procedure (European Community Bureau of Reference) and combined with the mass/volume proportions of each waste to quantify the potential risk of this mining district at regional scale. Analytical recoveries by sequential extraction, with respect to a pseudo-total metal content digestion, were generally acceptable (100 ± 17%). The oxidizable fraction corresponds with metals bound to sulphides and released easily under oxidizing conditions in AMD production processes. This is the most polluting fraction for the environment in this type of residues. Part of this fraction is retained by precipitation of soluble secondary minerals in warm periods, moving to the bio-available fraction that is dissolved in rainy periods. Just considering the bio-available fraction, all mine wastes from São Domingos may leach up to 172514 ton of Fe, 10564 ton of S, 6644 ton of Pb, 2610 ton of Zn, 1126 ton of Mn, 1032 ton of Cu, 183 ton of Cr, 109 ton of As, 34 ton of Sb and 0.9 ton of Cd. The process of precipitation and re-dissolution of efflorescent salts formed directly by oxidation of the oxidizable fraction is seasonally repeated, which causes an annual self-feeding and releasing of the bio-available fraction. Thus, the present study shows the pollutant potential of this IPB mining district and explains the spoiled state of the fluvial courses in the region. 相似文献
19.
Xavier Emery 《Mathematical Geology》2006,38(7):801-819
Multigaussian kriging aims at estimating the local distributions of regionalized variables and functions of these variables
(transfer or recovery functions) at unsampled locations. In this paper, we focus on the evaluation of the recoverable reserves
in an ore deposit accounting for a change of support and information effect caused by ore/waste misclassifications. Two approaches
are proposed: the multigaussian model with Monte Carlo integration and the discrete Gaussian model. The latter is simpler
to use but requires stronger hypotheses than the former. In each model, ordinary multigaussian kriging gives unbiased estimates
of the recoverable reserves that do not utilize the mean value of the normal score data.
The concepts are illustrated through a case study on a copper deposit which shows that local estimates of the metal content
based on ordinary multigaussian kriging are close to the optimal conditional expectation when the data are abundant and are
not dominated by the global mean when the data are scarce. The two proposed approaches (Monte Carlo integration and discrete
Gaussian model) lead to similar results when compared to two other geostatistical methods: service variables and ordinary
indicator kriging, which show strong deviations from conditional expectation. 相似文献