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By M. Samuels

"Block and panel cave mining methods are being increasingly proposed as they allow massive, deeply situated ore-bodies to be mined economically at a time when discovery rates of significant near surface deposits are declining. Cave-to-Mill, a mine-to-mill approach for block cave mines, defines ore block models with respect to both mine and mill performance. A cave-to-mill study for the New Afton block caving operation focused on identifying value opportunities related to fragmentation and sorting for a future lift as development progresses deeper. The lack of selectivity and potential for dilution associated with the block cave mining method results in many caving operations having to mine and either dispose of or process material that is below cut-off grade at certain stages of production. As an outcome of the study, the variation in cave fragmentation size and the sensitivity of mill throughput to feed size was examined. To evaluate the amenability of bulk and particle sorting, Prompt Gamma Neutron Activation Analysis and X-Ray Fluorescence sensors were tested. A conceptual bulk and particle sorting flowsheet is presented. Grade data from regular underground sampling was used to predict the performance of a bulk sorter. A heterogeneity analysis of material reporting to drawpoints helped to identify areas of the extraction level that experience high variations in grade and thereby stand to benefit from dedicated ore and waste material handling systems should underground bulk sorting be implemented.INTRODUCTION Block and panel caving are low-cost underground mass mining methods that are suitable for excavating weak, massive and steeply-dipping orebodies. Accordingly, cave mining methods have predominantly been used to mine copper porphyry and diamond bearing deposits. Due to the increasing depletion of near-surface orebodies, it is expected that block and panel caving methods will be increasingly used in the copper-gold industry. Their implementation holds significant potential to extend the life of existing open-pit operations by providing an economic means to access ore located at depths that are beyond the practical limits of open-pit mining. Examples of cave mines proposed for British Columbia include the Kwanika Mine, Red Chris underground, Kemess Underground project, and the Iron Cap and Mitchell cave mines of the Kerr-Sulphurets and Mitchell (KSM) project (Moose Mountain Technical Services, 2017; Imperial Metals, 2017; Golder Associates, 2017; Tetra Tech, 2016)."

Jan 1, 2018

By N. A. Beier, R. Amos, Smith. L., C. Atherton, D. R. Barsi, D. Blowes, D. C. Sego

"Waste rock is one of the most abundant materials at mine sites and must be properly characterized and managed to limit acid rock drainage and other harmful byproducts. An experimental waste rock pile—part of the test piles research program—located at the Diavik diamond mine (Northwest Territories, Canada) was deconstructed and sampled to study the spatial variability of material properties. Bulk samples were classified based on the amount of material finer than 4.75 mm. Hydraulic properties of each sample were estimated and particle size distribution analysis was completed. These datasets and classification methods might be used to improve the understanding of hydraulic and geochemical behaviour of the material and to study waste rock at other sites. ¦ KEYWORDS Acid rock drainage (ARD), Material classification, Particle size distribution (PSD), Waste rock RÉSUMÉ Les stériles font partie des matériaux les plus abondants sur les sites miniers et, en tant que tels, doivent être correctement caractérisés et gérés afin de limiter le drainage rocheux acide (DRA) et la pré¬sence d’autres sous-produits nocifs. Dans le cadre du programme Test Piles Research Program, un amas de roches stériles expérimental situé à la mine de diamant Diavik (Territoires du Nord-Ouest, Canada) a été décomposé et mis à l’essai afin d’étudier la variabilité spatiale des propriétés des matériaux. Les échan¬tillons en vrac ont été classés en fonction de la quantité de matériaux plus fins que 4,75 mm. Les propriétés hydrauliques de chaque échantillon ont été estimées et l’analyse de la composition granulométrique effectuée. Ces ensembles de données et méthodes de classement serviront à mieux comprendre le com¬portement hydraulique et géochimique du matériau et à étudier les stériles sur d’autres sites. ¦ MOTS CLÉS classement des matériaux, composition granulométrique, drainage rocheux acide (DRA), stérilesINTRODUCTION Statement of problem The characterization of mine waste rock remains a challenge in active mining sites. The large volume of material and the large size of particles make it difficult to collect representative samples. Sampling techniques are often dis-ruptive to mining operations because they alter the structure of the waste rock pile or interfere with mine traffic. The convention at most mine sites to collect little to no information on waste rock material means that models and predictions of how waste material will behave and interact with the surrounding environment are based on general information that might not be site specific. This could lead to environmental damage or higher costs if environmental effects are underestimated during the construction of waste rock structures."

Jan 1, 2019

By Denis Blackburn

La Direction générale du développement de l?Industrie minérale (DGDIM) du ministère des Ressources naturelles et de la Faune (MRNF) du Québec tient un inventaire de toute l?activité minière sur le territoire. Cet inventaire s?est enrichi, au cours des dernières années, d?un grand nombre de projets dédiés au fer ou à des substances qui y sont associées (titane, vanadium, phosphate). Actuellement, cinq régions du Québec sont principalement touchées par la recrudescence de projets dédiés au fer : Fermont, Schefferville, Baie d?Ungava, Baie-James et Chibougamau. Fermont et Schefferville sont les régions les plus actives. Les infrastructures en place, telles que les routes, les chemins de fer, les ports, les lignes électriques et les municipalités, ont atteint, dans certains cas, leur capacité et de nouvelles infrastructures devront être construites pour satisfaire les besoins. À la Baie-James et sur le flanc ouest de la Baie d?Ungava, des projets d?exploration sont aussi en cours. Le manque d?infrastructure pourrait peser lourd sur le développement de projets miniers dans ces régions. Enfin, dans le secteur Chibougamau/Matagami et à quelques sites ailleurs au Québec, des projets d?exploration qui visent le vanadium, le titane ou le phosphate pourraient aussi fournir comme produit secondaire des concentrés de fer. Tous les projets, décrits dans cet article, sont situés sur le territoire du Plan Nord du gouvernement du Québec.

May 1, 2011

By J. D. Campbell

"Coal is one of Alberta's major fuel resources, but its distribution, especially in the flat plains region, has been somewhat obscured by surficial deposits. After a period of neglect, easily strippable plains coal is presently approaching a position of dominance in electrical power production, a position it is likely to retain for a number of decades in the face of strong competition from hydro and nuclear power. Accordingly, the Research Council of Alberta has undertaken an inventory survey of the province's supplies of this resource.In the southern part of the province and in the north-central forest-fringe area, some strippable coal is found in the Belly River Formation and its equivalents, but major strippable coal reserves in large areas of central Alberta occur within the Edmonton Formation. The survey is planned on a reconnaissance scale, drilling test holes at 2-mile intervals in selected large areas. It appears to show that, in well-settled regions, large reserves of strippable coal are only to be expected where they have long been known; major presently unknown bodies of coal must be sought in unsettled regions or at depths too great for strip mining. However, such bodies might still be economically competitive with hydro and nuclear power in the production of electric power for some time to come."

Jan 1, 1967

By M. Tanaka, T. Oishi, K. Koyama, S. Alam

"A novel hydrometallurgical process for copper recovery from waste printed circuit boards has been proposed, which consists of selective leaching of copper metal as Cu(I) by Cu(II) in ammoniacal alkaline solution, purification, and electrowinning. The distinct feature of this process is much lower power consumption during the electrowinning than that during the conventional one from acidic copper sulfate media, because the deposition of copper metal from Cu(I) at the cathode and the oxidation of Cu(I) to Cu(II) at the anode take place in the present method. In the laboratory-scale tests using waste printed circuit boards, high purity copper which contains 1.1ppm of impurities was obtained in a chloride system. INTRODUCTIONThe recovery of various metals from waste materials is an important issue in order to conserve the environment and metal resources. Copper is used for cables, electric appliances, etc., and is currently a very important material for industries and will continue to be in the future. Among the wastes that contain copper, one of the most complex recycling materials is electronic scrap like printed circuit boards (PCB), which generally contain 10-30% copper as well as plastics, fibreglass and other metals. There are two ways to recover copper, either pyrometallurgical or hydrometallurgical. Hydrometallurgical treatments generally have more flexibilities in the process scale and control. The separation processes tend to become complicated because of the poor selectivity during the leaching in the sulphuric and hydrochloric acid media. On the other hand, the use of ammonia as a complexing agent, gave a higher selectivity for copper leaching (Nigo, Majima, Hirato, Awakura, & Iwai, 1993; Majima, Nigo, Hirato, Awakura, & Iwai, 1993; Zhou, Shinme, & Anezaki, 1995; Koyama, Tanaka, & Lee, 2006) .In this study, recycling process containing leaching, copper deposition at a cathode and oxidation of copper(I) at an anode from ammoniacal alkaline solutions containing Cu(I) or Cu(II) is introduced. Furthermore, copper recovery from a waste printed circuit boards and impurity behaviour was examined in ammonia-ammonium sulfate (sulfate system) and ammonia-ammonium chloride (chloride system) systems."

Jan 1, 2012

By Hani S. Mitri

Overhand cut-and-fill mining of narrow vein orebodies inevitably leads to the creation of horizontal pillars. As the thickness of the overlying crown pillar diminishes, stresses build up in the pillar. More often than not, this situation causes an increased level of seismicity and possible pillar burst. One well-known strategy to reduce the hazard of crown and sill pillar burst in cut-and-fill vein mining is that of destress blasting. The paper first reviews the methods used for the monitoring and assessment of potential pillar burst in narrow vein cut-and-fill mining. The influence of horizontal stress, mine depth and pillar thickness on stress build-up in the crown pillar is examined through a characteristic narrow vein numerical model. The paper then presents, with reference to three mine case studies, the benefits of destress blasting and the factors affecting its success as a ground control technique.

Oct 1, 2001

By M. Specht, D. Pörzgen, W. Lorenz, A. /. Buhr, R. P. Racher

The introduction of the near net-shape casting process at CORUS Staal IJmuiden in January 2000 required changes of secondary metallurgy processes including a development towards more aggressive slag compositions in the steel ladle. Therefore the steel ladle lining has been changed from fired andalusite bricks to magnesia-carbon bricks and, most recently, to fired spinel bricks to withstand the severe slag conditions. In comparison to the andalusite bricks the new steel ladle linings have a higher thermal conductivity. This requires the capability to keep the lining warm by ladle preheaters to sustain the overall thermal stability of the steel ladle in case of interruptions during hot cycling of the ladles.

Jan 1, 2004

By Min-Yuan Cheng

Heavy rainfall and typhoon oftentimes cause the collapse of hillslopes across mountain roads. Disastrous consequences of slope collapses necessitate the approach for predicting their occurrences. In practice, slope collapse prediction can be formulated as a deterministic classification problem with two class labels, namely ?collapse? and ?non-collapse?. Nevertheless, due to the criticality and the uncertainty of the problem, evaluating the collapse susceptibility of an area is a challenging task. This study proposes a novel Artificial Intelligence (AI) approach, named as K-Nearest Neighbor Based Bayesian Classifier (KNNBC), to deal with slope collapse assessment. In the proposed model, Bayesian inference is used as a framework to achieve probabilistic prediction of slope collapse. Meanwhile, K-Nearest Neighbor (K-NN) is employed as a density estimation technique. Equipped with probabilistic outputs, the K-NNBC is able to yield predictions with different levels of confidence and diminish misclassified cases. Experimental results point out that the proposed model is very helpful for decision-makers in slope collapse assessment and disaster prevention planning.

Aug 1, 2013

By J. Hendry, K. Brady, J. Yorzyk

Drawing from the experience of nickel, copper, aluminum and mineral borates, this paper illustrates the business value that the mining, minerals and metals industry as a whole can gain from applying life cycle assessment (LCA) to products and operations. Through the use of case studies, the paper explores how companies and industry associations have used LCA to their advantage: from evaluating capital investments, meeting customer information needs, supporting new product applications, and developing credible marketing information on the environmental performance of their products. It also explores the dynamics of LCA adoption and integration within companies, and provides recommendations to further strengthen institutionalization of LCA.

Jan 1, 2010

By Wei Wang

The SMCO copper plant is located in DR Congo, and was designed by China NERIN Engineering Co., Ltd. The process is a typical hydrometallurgical plant with Leach-SX-EW, with the project treating the oxide minerals with agitation leaching, followed with three stage of solvent extraction and two stages of stripping, and using permanent SS cathodes to produce LME grade copper. Because of the special characteristic of the ore, what contains 2 different type of oxides (one high carbonate oxide and the other low carbonate), there are several new technical measures that have been developed and adopted for the plant. For example, different grinding, leaching, and filtering are used to treat different oxides. This paper, presents the project process, engineering design, construction and commissioning. The paper also describes some of the problems encountered during plant commissioning, such as the agitation leaching tank issues, and corrosion in the settler-mixer. This paper discusses some NERIN solutions to these problems, and explains the use of the CN filter, which is used to filter PLS to treat high level suspend solids, instead of the traditional sand filter. Finally, this paper also proposes steps / measures for further improvement for future plant operation.

Jan 1, 2014

By Zhiqiang Wang

This paper mainly focuses on the method of ?three-zone? definition (a caving zone, a fissure zone and a curve subsidence zone) for full height cutting in a thick seam. Based on criteria of a caving zone and a water conducting zone, as well as existing research achievements, it is believed that there exists great error for calculation of height of the ?three-zone? area using cutting height and the coefficient of bulk increase. Dynamic factors should be considered, so, based on the theory of key rock strata and combining this with several other factors, such as mining area, this paper presents a new method to determine the overburden ?three-zone? definition. The results are as follows: (1) geometric models of a working face and key stratum are established through the rock displacement angle, with consideration of the influence of mining on the key stratum (the range of key stratum influenced by mining is enlarged as the mining area increases); (2) because there is always a cavity below the key stratum of the thick coal seam with full seam cutting, and the key stratum gradually fracture with face advancing, based on the geometric dimension of strata, the maximum fracturing interval expression has been presented, including the working face advancing range. This can theoretically lead to the location of the key stratum influenced by mining, and its stability before mining, helps to confirm which zone the key stratum and following-up strata belong to, using the criteria of sliding instability or deformation instability; (3) the new method of ?three-zone? definition which is based on the theory of key rock strata is first proposed for full height cutting in thick seam. Finally, combined with practical engineering, and comparing with field data, it is believed that the proposed method is more objective than existing methods.

Aug 1, 2013

By M. Greyling, C. Panaou, M. Bellino

Commonly the most frequent method of calculating the overall mass balance of a multi mineral platinum-group metal (PGM) concentrator circuit in Southern Africa has been through the use of spreadsheets, typically Microsoft EXCEL®. While there are some advantages in using spreadsheet based mass balances during the conceptual design phase of the project, their use becomes limited in the detailed design phase of the project. This paper discusses the successful application of METSIM® for mass balancing of a PGM concentrator and highlights the benefits gained during the conceptual and design phase of the project.

Jan 1, 2005

By X. G. Zhao, M. Cai, L. K. Ma, P. F. Li

"Crack initiation stress is one of the characteristic stress thresholds in the rock deformation process under compression. By analyzing AE responses of brittle rocks in uniaxial compression, a new method which is called cumulative AE hit (CAEH) method is proposed for determining the crack initiation stress. An advantage of the CAEH method is that the method removes the user's subjective judgment. To verify the CAEH method, uniaxial compression tests with AE measurement using 77 crystalline rock specimens were conducted. The test specimens cover eight rock classes with different mineral grain distributions. Crack initiation stresses of these specimens were determined by the proposed CAEH method and the LSR method, and the resulting mean crack initiation stresses determined using the two methods were comparable. In addition, taking one rock class with 20 specimens for example, the mean crack initiation stresses determined using the CAEH method and those from several established strain-based and AE-based methods were similar. Hence, the CAEH method can be used as an alternative method for crack initiation stress determination.INTRODUCTIONExperimental observations indicate that the failure process of brittle rocks is associated with crack initiation, crack propagation, crack damage and final strain localization (Brace et al., 1966; Bieniawski, 1967; Lockner, 1993; Wawersik & Fairhurst, 1970). Compression tests on cylindrical specimen are often used to characterize the crack development process. The crack initiation stress (sci), crack damage stress (scd), and peak stress (sc) represent important stress thresholds during the failure process of brittle rocks. Among the three characteristic stress magnitudes, sci is difficult to be determined objectively, directly from examining the stress–strain curves. Some researchers argued that sci obtained from laboratory compression tests is an important parameter for estimating the spalling failure observed in brittle rocks around underground excavations (Andersson et al., 2009; Diederichs, 2007; Martin, 1997). sci can also be used to estimate rock tensile strength and Hoek-Brown failure criterion parameter mi (Cai, 2010). Over the last 40 years, various strain-based methods have been proposed to determine the crack initiation stress in compression tests (Brace et al., 1966; Diederichs, 2007; Eberhardt et al., 1998; Lajtai, 1974; Martin & Chandler, 1994; Stacey, 1981). Nicksiar and Martin (2012) proposed a Lateral Strain Response (LSR) method for establishing sci for low-porosity rocks. Meanwhile, they also used different strain-based methods to evaluate sci of Äspö diorite, and the results showed that all strain-based methods gave acceptable crack initiation stress values. Subsequently, they utilized the LSR method to further investigate the crack initiation stresses in igneous, metamorphic, and sedimentary rocks in compression tests (Nicksiar & Martin, 2013). Compared with previously proposed strain-based methods, an advantage of the LSR method is that it removes the user judgment when interpreting sci. However, the use of the LSR method relies on accurate determination of scd and on having a polynomial fitting equation to find the maximum LSR value."

Jan 1, 2015

By C. A. Campbell

"There has been a significant reduction in maintenance hours and improved performance by maintenance crews at the MacLeod mine since the introduction of a Maintenance Control system which includes the use of maintenance standards. This paper deals with the steps taken to develop and implement the program. The objectives of the program and the organization and training of the control group are outlined. The work-order system, standards application, classification of work and the preventive maintenance procedures will be discussed.All maintenance information is processed on a Model 360-20 IBM computer, which turns out maintenance records and control reports for management action. Information in these reports, and reasons for reporting, will be discussed and the benefits resulting from the program reviewed."

Jan 1, 1973

By B. Dyck, L. Verhelst

"Colloidal silica in Key Lake’s Solvent Extraction (SX) feed solutions has presented an operational problem for the mill throughout its history. The colloidal silica stabilizes aqueous continuous emulsions, resulting in elevated solvent losses and operational downtime. Through the years, many attempts have been made to solve this problem, but no viable solutions were found. By revisiting an idea dating back to the 1979 feasibility study and re-evaluating it under current operating conditions, a practical solution was achieved. This paper discusses Key Lake’s history around colloidal silica removal, starting with coagulation using a polyethylene oxide polymer (PEO), and ending with coagulation using a polyethylene glycol (PEG) polymer. The results of a mill trial using POLYSIL® RM1250 introduced at doses up to 300 ppm into the counter current decantation (CCD) circuit to clarify SX feed solutions are discussed with a focus on the benefits to SX.INTRODUCTION Colloidal silica has historically been a significant operational problem in the Key Lake mill. Silica originates from clays in the ore as well as concrete backfill intermixed with the ore resulting from the mining method used at Key Lake’s ore source, the McArthur River mine. The silica is dissolved as silicic acid into solution in the mill’s sulphuric acid leaching circuit. Once in solution, silicic acid polymerizes (Hearn, Smethurst, & Boskovic, 2016) forming a fine suspension of stable colloidal particles. These silica colloids are unaffected by flocculants and sand filtration reporting to the pregnant leach solution (PLS) as a fine turbidity in solution. Silica concentrations typically ranged from 700 to 1200 mg/L Si in the PLS fed to SX. Throughout Key Lake’s history, silica interactions in the Solvent Extraction (SX) process have made SX a mill bottleneck and a source of significant reagent costs."

Jan 1, 2018

By S. A. Briggs

Bioremediation has been accepted as a treatment technique for groundwater contamination in subsurface soils and shows promise for contaminated fractured rock environments. Biological growth in fractured rock is expected to occur predominantly as biofilms attach to the fracture surfaces. Biofilms in rock fractures are subject to a complex system of forces and other phenomenon due to the dynamics of the bulk fluid in which they grow. In this paper, through the applications of computational fluid dynamics (CFD) to rock fractures, where the boundaries are rough and the flow is complex, a precise analysis was conducted of the interaction of a fluid flow and the rock fracture. Specifically, hydraulic parameters and velocity profiles of an actual rock fracture were calculated and compared to a fracture of equivalent aperture. From the analysis it is clear that it is important to use more complex models such as the Lattice Boltzmann Method used is this paper to describe fracture flow.

May 1, 2009

By T. Alan O'Hara

"Annual mining revenue can be computed by formulae relating metal prices, smelting schedules, concentrate grade and recovery to known ore grade and an assessment of core samples. Operating costs at different daily tonnages are related to orebody shape, mining method, milling process and general plant services. Capital costs are related to sizing of mining equipment, mine development, plant-site topography, climate and accessibility, plant services and personnel housing. IntroductionA crude guide to the average 1978 cost of mine projects is shown in Figure 1, but the costs of many mine projects have differed widely from the graphed average costs of $800,000 T0.6 for underground mine/mill projects and $400,000 T 0.6 for low-grade open-pit mine/mill projects.High mine project costs and high operating costs are characteristic of open-pit mines with high stripping ratios, underground mines with thin orebodies, mills with complex metallurgy, and projects located in isolated regions with severe climate, mountainous topography, and lacking access to existing roads, towns and electric power. When none of these adverse conditions prevailed, the mine project cost was typically much less than the graphed average cost. Virtually all the conditions likely to cause high capital and operating costs are known from knowledge of the local topography, climate or accessibility, or can be assessed by tests on core samples, as soon as the orebody has been outlined by drilling .A more accurate estimate of over-all project capital cost and operating cost can be made from a summation of items of cost after judging the effect of specific local conditions on each item of capital and operating cost. This paper offers guides in judging the effect of local conditions on the sizing and 1978 cost of specific items of capital cost and operating cost and operating cost of mine projects. When the specific items of capital cost and operating cost are totaled and measured against expected net revenue and taxes over the life of the mine using the net-present-value or discount-cash-flow methods, the result should show whether the mine project development is clearly feasible, doubtfully feasible or clearly uneconomic. If the development of the mine project is clearly feasible, or probably feasible, a detailed feasibility study by experienced consulting engineers should be commissioned before any financial commitments are made; but if project development appears to be uneconomic, the time and cost of a detailed feasibility study is not warranted."

Jan 1, 1980

By C. Jay Hodgson, P. J. MacGeehan, T. Sanders

"The orebodies of the Campbell and Dickenson mines are localized within an anomalously fissile and deformed zone that transects the eastern margin of a dominantly mafic volcanic complex close to its contact with a synchronously formed sedimentary basin containing clastic and chemical sedimentary rocks. The ore zones are mainly quartz-carbonate fissure veins and siliceous replacement zones formed during deformation and metamorphism, although there are some syn-volcanic exhalative ore zones in the mines. On a regional scale, the volcanic rocks have been affected by syn-volcanic spilitic alteration which has involved the leaching of Fe, Mg, Au and As from, and the addition of Na and variable amounts of Si to bleached zones enveloping primary permeable structures in the rocks. The leached constituents were deposited on the contemporaneous sea floor as iron-rich chemical sedimentary rocks. Although this alteration is not closely related, spatially, to the ore zones, it is characteristic of the general environment, and may serve to distinguish gold-prospective from gold-barren areas on a mining-camp scale.Closely associated spatially with gold deposits is a zone of feldspar-destructive alteration within which the volcanic rocks are characteristically feldspar-free, enriched in As, Au and to a variable degree in Si, and depleted in Na, Ca and to a variable degree in Mg, Fe and K. The alteration zone is also characterized by abundant, variably transposed, small quartz-dolomite to ferrodolomite veinlets formed during deformation and metamorphism, and includes, but extends outside of, the anomalously fissile zone hosting the orebodies. The alteration zone is interpreted to have formed syn-volcanically within the upper part of a major submarine hydrothermal discharge zone."

Jan 1, 1982

By A. J. Reed, W. R. Bergey, Carr. J. M.

"The Highmont copper-molybdenum deposits are at Gnawed Mountain in the Highland Valley porphyry copper district, 125 miles northeast of Vancouver. This district is near the center of the lower Jurassic Guichon Batholith, where a north-trending swarm of porphyry dikes is crossed by west-northwesterly structural belts in which fracturing, intrusion of porphyry and breccia, and mineralization areconcentrated.The Highmont deposits are 2 miles southeast of, and in the same southernmost structural belt as, the Lornex deposit. The main deposits occur on either side of a composite dike of granodiorite, porphyry and breccia which strikes west-northwestward in fractured quartz diorite. North of the dike, the adjacent Nos. 1 (East) and 2 (West) zones together contain 150 million tons of open-pit ore mineable in two separate pits. These two zones will support a 25,000-tpd mill with a grade in the first five years of approximately 0.46 per cent copper equivalent. South of the dike, the Nos. 3 and 4 zones are partly explored and will provide large additional reserves. In these various zones, chalcopyrite, bornite and molybdenite form disseminations and fracture-fillings accompanied by quartz, K-feldspar, tourmaline, sericite, specular hematite and other minerals. Bornite extends for varying distances north of the dike, beyond which chalcopyrite is locally accompanied by pyrite. Higher-grade mineralization tends to coincide with fracture swarms, or with shear zones and faults which largely parallel these swarms. The ore zones are reflected by geochemical soil anomalies which show some glacial dispersion. LP. surveys gave weak but significant responses, expressed as per cent frequency effect. The ore zones occur within a strong magnetic gradient, but do not show a significant magnetic response."

Jan 1, 1971

By Garston Blackwell

Abstract - During geostatistical estimation of block grades, the kriging process produces a measure of error, the kriging variance or the kriging standard deviation. Estimation of the block error depends on the semi-variogram model for a deposit, which reflects fundamental characteristics of a deposit such as (1) nugget effect, (2) range of influence of grades, (3) different local spreads of data as a function of average grade (proportional effect), (4) nested structures, and (5) underlying anisotropies in the data; this model may be affected by sampling or assaying limitations, however. Because the kriging error incorporates so many features of both the deposit and data to be used for estimation, it may offer a substantial improvement on block classification over traditional procedures such as data density. Practice indicates that the relative kriging standard deviation (RKSD) is particularly useful for block classification in measured, indicated and inferred categories. Plots of RKSD in plan and section also can be used to demonstrate where extra drilling and sampling would be most advantageous for upgrading the class of some blocks. Moreover, the use of grade and RKSD filters can show where material near cut-off grade is poorly defined, indicating sampling target areas to improve block classification in the vicinity of the ore-waste boundary.

Jan 1, 1998