Search Documents

By Louis R. Bernier

Most systematic studies carried out on passive treatment systems incorporating the use of limestone drains, under aerobic or anaerobic conditions, essentially deal with the treatment of effluents from mines in the USA. A limestone drain typically comprises a trench filled with crushed limestone rocks surrounded by impervious materials. In the case of anoxic drains, the trench is generally isolated under a geomembrane liner covered with soil. Contaminated mine effluents flow by gravity towards these limestone drains where the passive treatment consists in bringing the carbonates into solution, thus increasing the pH and alkalinity. Factors to be considered in the design are: chemistry of the contaminated mining effluent ([metals, [Al], [sulfates], dissolved oxygen, acidity, pH), desired residence time, nature of the rock, grain size, density, void ratio and mass of the limestone rock used, alkalinity, life span and hydraulic behaviour of the drain. Certain secondary effects (saturation by sulfates, co-precipitation, adsorption) may either be beneficial (lowering the sulphate and metal load) or harmful (armoring the limestone rock and clogging of the drain). This paper gives a brief status report on the available knowledge on the use of limestone drains for passive treatment of mining effluents heavily loaded with metals. Examples given include the old Lorraine mine (Ni-Cu), Témiscamingue, where limestone and dolomite rock drains were installed in 1998 when a cover with capillary barrier effects was placed over the tailings site.

Nov 1, 2002

By S. Nakamura, K. Fujiwara, S. Hirosawa, S. Tsukamoto, Y. Koshino, Y. Aruga

"In this study, hardness test, differential scanning calorimetry(DSC)and transmission electron micros copy were carried out to investigate the age-hardening behavior of Al-Mg-Si alloy with a Mg+Si concentration of 1.5mass%, and a Mg/Si ratio of 1.0. Pre-aging treatment was conducted for the solution-treated and then water-quenched specimen at 100, 80, 60, 40, 20 (natural aging), 0 and -20°C for 20min or 5h, followed by artificial aging at 170°C for 20min. It was found that when pre-aging time is prolonged from 20min to 5h, the bake-hardening response is deteriorated irrespective of the pre-aging temperature. In particular, the specimens subjected to pre-aging at 20-40°C for 5 h hardly increased the hardness with the subsequent artificial aging. From the results of DSC measurement, it was suggested that as pre-aging temperature is lowered, the amount of solute clusters formed during pre-aging, i.e. Mg-Si clusters and Si-rich clusters, is decreased, but the ratio of Si-rich clusters is increased, resulting in the deteriorated bake-hardening response.INTRODUCTIONIn recent years, Al-Mg-Si alloys have been widely used forautomotive body panels due to their excellent characteristics such as high strength-to-weight ratio and good formability. Their strength is increased not only by artificial aging during paint-bake treatment; i.e. “bake-hardening”, but also when kept at room temperature(RT);i.e. “natural aging”, in association with the suppressed bake-hardening response. Such a “negative effect of two-step aging” has been a serious problem because Al-Mg-Si alloy coils are unavoidably maintained at RT in the manufacturing process of body panels; e.g. shipping and storage. However, it was reported that pre-aging above 70°C before the two-step aging can restore the bake-hardening response, and such an improvement is related to the formation of solute clusters(Sato, 2006; Abidet al., 2010; Takaki et al., 2014; Zandbergen et al., 2015). From the comprehensive analysis by three-dimensional atom probe (Aruga et al., 2014 and 2015), it is believed that Mg-Si clusters formed during pre-aging transform into the strengtheningß"" phase, whereas Si-rich clusters formed during pre-aging act as a detrimental precursor of ß""phase. In this study, it was aimed to investigate the effect of pre-aging conditions, especially pre-aging temperature and time, on the formation of solute clusters during pre-aging, in order to elucidate the mechanism of the age-hardening behavior of an Al-Mg-Si alloy."

Jan 1, 2018

By Robert B. Parsons

"It is generally felt that flow-through shares face a bleak future under the set of tax rules proposed in the federal government's tax reform white paper. Industry and government circles are beginning to give thought to alternatives to flow through as a mechanism for facilitating equity financing in the exploration industry. Despite suggestions that grants and tax credits may someday be on the table, industry is sticking to its position that there is no substitute for flow-through. Alternatives toFlow-throughProposals in the federal government's tax reform white paper have cast significant doubt on the ability of the mining industry to raise risk capital after 1989by way of flow-through shares. There is serious concern that introduction of the ""cumulative net investment loss"" (CNIL) rules, the phase-out of the mining explorati0! 1 depletion allowance (MEDA), and the Increased capital gains inclusion (750/0 versus 50%, at present) will make the economics of flow-through so unattractive after 1989 that these shares will hold little appeal to most investors. The question might be raised, then, as to what alternatives exist by way of tax or other government assistance that could help the exploration sector.The purpose of this paper is to survey the types of government incentives that could be of some value to explorationists and to the mining industry in general. For the past several years, flow-through has been in the spotlight insofar as incentives to the exploration industry are concerned. Other potentially useful and attractive incentives have been partially hidden in the shadow of flow-through. These incentives, in certain circumstances, can be of considerable benefit, and should not be ignored."

Jan 1, 1988

By Jorge Blanco, Joaquin Gotor, Enrique Delgado, Carlos Frias

Since 2009 Cobre las Cruces (CLC) has successfully operated a sustainable mining business near Seville, Spain, applying the most advanced hydrometallurgical technologies to process secondary copper sulphide ores through atmospheric leaching in ferric sulphate media and using oxygen sparging in a cascade of ten reactors. In comparison to conventional copper smelters, the CLC hydrometallurgical process does not generate SO2 gas, airborne emissions or slags. The copper ore is ground and sent directly to atmospheric leaching reactors; flotation is not required, and consequently, copper extraction is maximized at 93-95%, while producing 72,000 t/y copper cathodes of the highest purity (99.999 wt.% Cu, Grade A). Reserves for the CLC deposit were estimated at 16 million tonnes of ore averaging over 6 wt.% Cu and containing principally a chalcocite mineralization. Other copper bearing species include digenite, covellite, chalcopyrite, bornite and enargite. Pyrite represents over 70 wt.% of the ore. In the CLC leaching process, chalcocite reacts with ferric sulphate at approximately 90 ºC and copper is released into solution while ferric ions are reduced to ferrous ions. The ferric sulphate leachant is regenerated continuously by oxygen injection and consumes sulphuric acid. It is remarked that pyrite plays a crucial role to yield high copper leaching rates. When pyrite is oxidized, a small proportion of iron is co-leached and some sulphuric acid is generated. The CLC leaching technology has been designed to allow a certain level of pyrite oxidation, which is positive in many ways: (i) to maintain a Fe/Cu ratio in solution; (ii) to facilitate Fe(II) oxidation; (iii) to produce a high redox potential; and (iv) to counterbalance a bleed solution that removes some iron. Moreover, galvanic interaction between pyrite (cathode) and chalcocite (anode) can substantially increase atmospheric leaching kinetics and efficiency (copper recovery).

Jan 1, 2016

By Bert Taylor

"The Mining concessions of Quemont Mining Corporation, Limited, are located at 48°16'N latitude, 79°00'W longitude, in Rouyn township, northwestern Quebec. Six hundred and forty acres in area, they lie directly north of, and contiguous to, the Horne mine of Noranda Mines Limited. The north arm of Osisko Lake covers a large area of the southern part of the property. The orebodies lie below the Jake with one body extending through to the bedrock surface.The property was staked in 1922, and was originally known as the Murray Claims. The group attracted interest from numerous exploration companies because of the proximity of the Noranda orebodies.The United Verde Extension Company, of Arizona, optioned the claims in 1926. They sank a shaft to a depth of 235 feet, at a short distance from the Noranda boundary. From a level established at a depth of 215 feet they completed 3000 feet of exploratory driving from which 6000 feet of diamond drilling was done. Only a small body of siliceous gold ore was found before they dropped their ·option.In 1928, The Mining Corporation of Canada purchased a 90 per cent interest in the property. An operating company, later named Quemont Mining Corporation, was formed. An electrical survey was carried out on a portion of the property, followed by deepening of the shaft to 922 feet. Levels were established at 500 and 900 feet, and 4,800 feet of driving and more than 3000 feet of diamond drilling were carried out from them.Geological knowledge at that time recognized that a major break, the Horne Creek fault, lay not far inside the south boundary. Striking north 80 degrees east, the fault dipped south at 85 degrees. The rock on the north side of the fault was massive rhyolite; to the south, meta-diabase and a little rhyolite. A left-handed movement was indicated by a 600-foot offset on a north striking diabase dyke. The small body of siliceous gold ore, referred to previously, was confined to the 215 level."

Jan 1, 1949

This paper generalizes open stopes into elliptical cross sections and applies the results of calculations based on the mathematical theory of elasticity to indicate stress distribution on the boundaries of such stopes. These show both compressive and tensile stresses and provide an ex-planation for the development of excessive dilution in shrinkage toping. Introduction T HE stress pattern around shrinkage stopes is identical with that around other stopes under the same physical conditions. However, a shrinkage stope ends as an unsupported open stope, and the method i limited to the stress range within which the rock is generally self-supporting. If it is acceptable to generalize the outline of a shrinkage stope into an elliptical cross section, then the graphs of Geldart & Udd (1) (see also Panek (2) and Denkhaus (3)) provide a good base for approximating the stress distribution as mining progresses. However, with failure conditions in the walls, the axis ratio, as cut

Jan 1, 1964

By S. Jordanov

The nature of processes that take place on top of copper bearing grains during the suppression of copper acid drainage from mine tailings was studied on a grain model. Cyclic voltammetry (C.V.) was employed as an experimental technique suitable for indirect measuring of copper leaching. Experiments were done in sulfuric acid (pH=2) at electrodes that progressively approach the real situation during acid main drainage, starting with Cu-metal, then with CuO and finally with CuO covered with CaSO4. Oxidation was found to be the only process that takes place on metallic copper electrode anodically polarized up to 2 V vs. Cu/CuSO4 reference electrode. Dissolution is intensive and reaches up to 50 mA.cm-2. When the same was repeated, but on CuO electrode, anodic currents were some 4 times lower than on the bare metallic surface. This indicates that the electrode material is not completely oxidized to copper(II)oxide and the Cu(O) or Cu(I) residues are oxidized during the anodic polarization. This explains the diminished dissolution. Dissolution is further restricted at electrodes covered with CaSO4. It is some 20 times lower than on the bare oxide electrode. When the second layer of CaSO4 was applied, anodic currents were another 15 times lower. Total decrease of anodic currents when transition is made from Cu-metal to CuO covered with 2 layers of CaSO4 reaches up to 7.500 times. C.V. measurements produced a proof that mechanical blockage is the way how lime prevents leaching of copper bearing grains in immobilization experiments referred elsewhere.

Jan 1, 2007

By G. Vibert Douglas

"Gold occurs in Nova Scotia in three ways, saddle reefs, fissure veins, and fossil placers. Of these the saddle reefs are the commonest. They have been the source of most of the gold and have also been the subject of most of the literature on the gold occurrences.The Meguma or Gold-bearing series of Nova Scotia is a conformable succession of quartzite's and slates, possibly Precambrian in age, which have been folded into a number of anticlines and synclines that strike (Fig. 1) roughly east and west. This folding has been termed Acadian and is probably a westward continuation of the Caledonian revolution in Britain. It may have started in the Ordovician and continued through the Silurian and into the Lower Devonian. It was followed by the intrusion of the great Devonian granite batholiths. It is thought that the mineralization is connected with the late phases of the cooling of the granite. As the name saddle reef implies, the veins form on the crests and flanks of the anticlines, possibly in the synclinal troughs as well. The beds favoured by the solutions are the slates. The reason for this is apparent when it is realized that in order to fold over 30,000 feet of sediments (the thickness of the Meguma according to E. R. Faribault) through p radians of arc it is necessary to have a differential movement between the top and bottom beds of p times the thickness of the sediments. In the case of the Gold-bearing series, in which strong quartzite beds lie between incompetent slate beds, most of this differential movement was taken up in the slates. The evidence for this is the remarkably fine drag folding and the intense shearing and comminution of some of the beds of slate (Fig. 1). The quartzites exhibit some shearing and faulting, but there is little doubt that the greater permeability lay along the incompetent slate beds. The mineralizing solutions followed these beds and also passed from one slate bed to another through a joint or fault in the intervening bed of quartzite. These joining veins are called angulars in Nova Scotia. Within the veins the gold is in shoots and the real problem is to find out what controls the position and extent of the shoots."

Jan 1, 1954

By J. E. Dutrizac, J. B. Sunstrum

"Lead was among the first metals known to man, and there are indications that lead was produced by the reductive smelting of galena in the mountains surrounding the Black Sea as early as 3000 B. C .(1). The early metallurgists soon discovered that silver could be recovered from lead bullion by cupellation techniques, and that the litharge product of the cupellation process could be reduced to give silver-free lead metal. By the Graeco-Roman era, lead-silver ores were being extensively exploited for both their silver and lead contents. Although silver was always of prime concern, a number of industrial uses existed for lead that included piping and sheeting. Subsequently, lead metallurgical practice developed steadily in different parts of the world, and was a relatively mature technology by the time of the European colonization of North America. In the United States, lead was produced on a small scale as early as 1720, and by 1800, the extensive Pb-Zn deposits of Missouri-Kansas and the upper Mississippi Valley were being developed(2). Many of the early American lead ores were low in silver, and seemed to have been worked primarily for their lead contents. Major uses of lead at the time included bullets, pipe and sheeting. During the period 1860-1890, the silver-rich galena ores of the western United States were exploited, and a number of lead smelters were operated. Although all the smelters produced lead metal, the recuperation of the associated silver and gold values was generally of prime concern. In Canada, lead deposits are abundant, and galenarich outcrops frequently attracted the attention of the early explorers and prospectors. In fact, the first record of a Canadian ore deposit seems to have been the observation of an argentiferous galena vein near Lake Temiscamingue in 17 41(3). The presence of silver-bearing lead deposits naturally attracted the attention of the mining community, and many outcrops were worked throughout the country. Because of the problems associated with transporting lead concentrates to existing American or overseas smelters, attention soon shifted to the establishment of local lead smelting facilities. The purpose of this article is to examine those early smelting efforts and to try to identify the first ""successful"" Canadian lead smelter."

Jan 1, 1999

By S. Ivanova

The results presented in this paper show that the gold solution dilution is a key parameter to control the dispersion of gold on ?-Al2O3 the selected support. The variation of concentration leads to changes in pH which modify the nature of gold complexes from HAuCl4 formed in the solution. These complexes are presented. Some of them (AuCl3(OH)- and AuCl2(OH)2 -) react with the surface of alumina and give interesting interaction. AuCl2(OH)2 complex has been considered as an ideal complex because of the strong anchorage of a bidentate species on the alumina. This complex is formed mainly in a solution of gold with a concentration of 10-4 M giving a pH of 3.5-4.5. The nature of the anchorage and the amount of chlorine, has an influence upon the formation of Au-Cl bridges which modify the dispersion of the gold on alumina of the final catalyst as shown by TEM.

Oct 1, 2003

By Marc Tardif

"The way alarm information is provided to an operator can make a huge difference in the minutes following an upset. Process alarms are often looked at as a way to help avoid catastrophic failure and serious accidents. But knowing that mineral processing is so energy consuming and that raw material is not consistent, all small upsets should also be seen as a catastrophe because they can have significant impact on product cost and quality.This paper will demonstrate how it is possible to use data from process alarms to provide operators with real time, value added information that will help them take the right decision at the right time and in turn, reduce unplanned downtime by 20 to 80% and incidents by up to 50% (number and cost),and optimize energy and capacity usage.In the era of Big Data, living in a world where we are submerged with information, one of the biggest challenges is to find the right information at the right time.Alarm rationalization projects will often focus on alarm quantity, but alarm quality is also very important. It is possible, by following a simple 6-step process to turn “alarms” into truly valuable information for operators. Based on known standards (ANSI/ISA 18.2 and EEMUA 191), this process will capture the knowledge of the best and most experienced operators and process engineers, and make it readily available to everyone, right on time, when it matters the most.INTRODUCTIONWhen spending some time in a modern control room, it is easy to notice the huge quantity of information that is available to the operator. Modern operation stations feature multiple screens with HD capability. These screens display information like process display, history trends, alarms and events list, maps with geo-located information, images from live cameras, etc. However, it is harder to assess whether all this information is really helping operators: Is all the information relevant? Are process screens overcrowded? Is the information easy to understand? Does the operator know what to do with all the information? Are there too many alarms?"

Jan 1, 2016

By Ajit K. Sinha

"Electromagnetic surveys were conducted over the Yava sandstone-hosted lead deposit in Nova Scotia to evaluate the usefulness of such surveys for detecting and mapping sedimentaryhosted metallic ore deposits. Both transient and multifrequency systems were used for that purpose. The deposit consists of three zones of disseminated galena which also contain minor amounts of pyrite and sphalerite filling the interstices of the sandstone grains. Each zone overlies a basement depression and is separated from the adjacent zone by an intervening basement high. A conductive shale layer underlies the galena-rich sandstone formation at all three zones.Because the concentration of galena (3070 to 4% ) and other sulfides is too low to affect the resistivity of the sandstone formations for detection by ground electromagnetic (EM) methods, the strategy for our survey was to look for areas of basement depressions and the presence of conductive shale in those depressions by EM depth soundings. The presence of the galena-rich sandstone formations could be inferred because of the close association of these two features with the deposits in the Yava area. Both transient and multifrequency EM systems were successful in mapping the basement depressions and detecting conductive shale at the three known mineralized zones. The technique, therefore, seems to offer good prospects for mapping similar stratabound sedimentary-hosted sulfide deposits."

Jan 1, 1993

By T. Saksala

In this paper, the embedded discontinuity approach is applied to finite element modeling of rock fracture. A rate-dependent constitutive model based on the embedded displacement discontinuity theory is developed to describe the mode I, mode II and mixed mode fracture of rock in tension and compression. The bulk material is described as linear elastic until reaching the elastic limit. Beyond this limit, a ratedependent exponential softening law governs the evolution of the embedded displacement jump. The present approach incorporates the rock heterogeneity by random description of the mineral texture of rock. Moreover, the inherent initial microcrack populations of natural rocks are accounted for as randomly oriented embedded discontinuities. Numerical examples demonstrate the model behavior in uniaxial compression and tension. The effect of loading rate and confining pressure is tested as well in 2D numerical simulations. These simulations show that the model captures the main features of rock in confined compression and uniaxial tension. The developed method has the computational efficiency of continuum plasticity models. However, it has an important advantage of accounting for the orientation of introduced microcracks.

Jan 1, 2015

By M. Remillard, M. Garon, M. Thérien, D. Hodouin

"Nineteen streams in the copper and zinc flotation units of the concentrator of the Matagami division of Noranda Inc. have been sampled for particle size distributions chemical assays, and gold and silver contents in each particle size interval. The data are upgraded by the mass balance package BILMAT. These results, in conjunction with microprobe analyses, are used to quantify the silver losses in the copper clean¬ing flotation stages and to determine how overall silver and three silver-bearing minerals are recovered in the plant final products.RESUME Dix-neuf produits des circuits de flottation du cuivre et du zinc de la division Matagami de Noranda Inc. ont été échantillonnés pour leur distribution granulométrique, analyses chimiques et le contenu d'argent et d'or des fractions granulométriques. Le bilan métallurgique a été obtenu à l'aide du programme BILMAT. Ces résultats couples avec une etude minéralogique à la microsonde sont utilises pour quantifier les pertes argentifères aux diverses étapes de nettoyage du circuit de cuivre et pour de¬terminer la repartition de l'argent et des trois minéraux argentifères dans les produitsfinals de l'usine.INTRODUCTION The Matagami division of NORANDA INC. produces copper and zinc concentrates from a sulphide ore which contains a small amount of gold (0.34 g/t) and silver (20 g/t). Only a small part of the silver (~-30%) is presently recovered in the copper concentrate. The objective of this study is to evaluate the metallurgical behaviour of silver, and secondarily of gold, in the flotation circuit for a possible increase of its recovery in the copper concentrate to improve its economic value. For that purpose it is worthwhile to study the minerals which bear silver and to determine the critical flotation stages where they are lost in the tails. The methodology proposed here is based on a coupling of a mineralogical study and a detailed mass balance calculation in the flotation circuit."

Jan 1, 1986

By Robert B. Parsons

"The customary onslaught of government budgets this spring offers lots of interesting reading to the mining industry.While the favourable changes tend to get all the fanfare, there are some ""sleepers"" in the host of proposed changes which will be bitter pills for some mining people to swallow.IntroductionOn a scale of one to ten, the Canadian mining industry will probably give this year's federal and provincial budgets a score that is pretty close to five. Although some budgetary proposals are generally perceived to be favourable to the industry, there are other provisions (and lack of provisions) which are considered to be negative.This month, Tax Notes examines in a summary manner the principal features of the 1985 federal and provincial budgets which are of particular interest to this country's mineral industry."

Jan 1, 1985

By Li Qihou, Liu Zhihong, Liu Zhiyong, Yao Wei

Black copper sludge, which mainly contains copper, arsenic and a little antimony, bismuth, selenium, tellurium, is an important recyclable secondary resource. In this paper, selective removal of arsenic from black copper sludge by alkaline oxidative pressure leaching was studied. The influences of alkali concentration, leaching time, leaching temperature, oxygen pressure, liquid-solid ratio and other variables on the leaching rate of arsenic, copper and tellurium were investigated. The results were as follows: when the leaching process was conducted at initial alkali concentration of 1mol/L, liquid-solid ratio of 10, stirring rate of 500r/min, leaching temperature of 140°C for 5 h and oxygen pressure of 2.5MPa, the leaching rates of arsenic and tellurium were 85.43% and 59.7% respectively, and copper, antimony, bismuth were not leached. Hence, arsenic has been removed effectively from black copper sludge, while the valuable metals such as copper, antimony and bismuth remained in the residue that can be further recovered easily. INTRODUCTION Black copper sludge is a byproduct in the purification process of copper electrolyte. Arsenic, antimony and bismuth are major harmful impurities in copper electrolytic refining system. The accumulation of these impurities will cause adverse effects, such as the increase of electrolyte resistance and power consumption and deterioration of cathode copper quality (Wang, Liu, & Zhang, 2001). Hence, electrolyte purification is an essential part of the electrolysis process (Liang, Chen, & Guo, 2009). Electrolyte purification methods include electrowinning (Davenport, King, Schlesinger, & Biswas, 2002), solvent extraction (Navarro, Simpson, & Alguacil, 1999), ion exchange (Arroyo et al., 2017), coprecipitation (Wang et al., 2003, 2018; Xiao et al., 2007; Xiao, Cao, Mao, Shen, & Ren, 2014), activated carbon adsorption (Navarro & Alguacil, 2002), electrodialysis (Cifuentes et al., 2015), redox process (Zhou, Peng, Zheng, Ma, & Cui, 2011; Peng, Zheng, Zhou, & Chen, 2012; Zheng, Peng, Ke, & Chen, 2013), among which the electrowinning method is simple in operation and effective in impurities removal, making it the main process for current electrolyte purification. Some copper ions can react with harmful impurities to form complex black copper sludge by controlling the operation conditions of electrowinning process. Based on the estimated data provide by Davenport et al. (2002), an annual output of 400,000 tons cathode copper could produce 432-2168 tons of black copper sludge by electrowinning method. Black copper sludge contains 30~50% copper, 15~30% arsenic and a small amount of rare elements such as selenium and tellurium. Thus, recovery of valuable metals can bring huge economic interests. Moreover, arsenic in these sludges could cause significant environmental pollution. Therefore, effective removal of arsenic from these sludges is urgent and significant.

Jan 1, 2019

By Y. Obara, A. Sato

"Limestone is one of the most important mineral resources, and in Japan it is only one mineral which can be fully supplied by the domestic product. Generally limestone mines in Japan located at mountainous regions, and the combination between bench-cut method and the carry-out system using vertical shaft is widely used in the domestic mines. During mining operations, the occurrence of the blockage in the vertical shafts is very serious problem. Once the blockage in the shafts is occurred, a lot of works and dangerous procedures are necessary to solve the problems. It is thought that blockage is influenced by the cohesion and friction coefficient due to clay minerals thrown into the vertical shafts, however, the quantitative and precise reason is not revealed yet.In this study, the process of blockage occurrence was simulated by 2-Dimensional Discrete Element Method (DEM). In the 2D-DEM analysis, discontinuous circular particles are generated, and the individual movement of each particle is calculated by forward difference method. In the analysis, several typical ore distributions are applied, and the DEM analysis was conducted under the various combinations of cohesion and friction coefficient. From analytical results, it was found that the friction coefficient strongly influences to the occurrence of blockage and there were a threshold values which blockage does not occur. Several kinds of shaft shape were also simulated towards different ore size distributions, and those influences to the blockage occurrence were also discussed."

Jan 1, 2015

By Bo-Hyun Kim

Outline ? Strainburst criteria and hypotheses adapted for this study. ? Influence of excavation method on rock mass properties. ? Excavation disturbance factors vs. deformation modulus, etc. ? Estimation of blasting damage zone around excavation. ? Considerations of energy on burst-prone ground. ? Literature review & closed form solution. ? Numerical simulations. ? Summary and future works.

Oct 1, 2010

By David Meadows, Elmer Palmer, Steve Dixon

As part of the Goldcorp Inc growth plan Minera Peñasquito SA de CV has developed its polymetallic deposit with a large “state of the art” concentrator to process lead and zinc ores. The plant consists of two grinding lines including 38ft diameter SAG mills and 24ft diameter ball mills. During mid to late 2009 concentrator commissioning activities commenced. First concentrates were produced in October 2009 and now the plant is meeting its design basis of 65,000 mtpd per line. This paper describes the design and operational experience to date for its grinding circuit design, together with the recently commissioned HPGR crushing circuit.

Jan 1, 2012

By L. Dekker

"In 1979 Chevron Standard Limited and Irving Oil Limited intersected a thick, high-grade sylvinite zone in the Windsor Group in the Chevron Irving Malagawatch No. I well in central Cape Breton. This well was the third and final hole of a program designed to evaluate a non-commercial oil discovery made by Chevron Standard's Mineral Staff in 1978 while carrying out base metal exploration. Nine holes were subsequently drilled to evaluate the significance of the potash discovery. The delineation drilling proved the Malagawatch structure to be complex with the potash zone showing erratic grade and thickness distribution. Based on the drill information the potash accumulation at Malagawatch is uneconomic, however, other salt ""structures"" in the Bras d'Or Basin may in time prove to have better potential.History of DiscoveryIn 1972 Cuvier Mines discovered the Gays River lead-zinc deposit (MacEachern and Hannon, 1974) which prompted Chevron Standard's Minerals Staff to carry out a study of the Windsor basins in Nova Scotia (Figs. I and 2). As a result of this program several carbonate-hosted lead-zinc prospects were identified in the basal Windsor carbonate; one of these was at Malagawatch on Cape Breton Island . In 1978, after preliminary exploration surveys, a diamond drill program commenced consisting of 5 BQ holes (Fig. 3), three of which tested the basal carbonate. Instead of the reefoid bank facies of the Gays River Formation (Giles et al., 1979), the favoured host for economic base metal mineralization, this carbonate was developed as a laminated, pelletoidal, lime packstone more characteristic of the facies equivalent Macumber Formation (Schenk, 1967). While drilling one of these holes, No. 3-78, oil scum was intermittently detected on the drilling mud. The hole was abandoned at 191 m in anhydrite, without having reached the basal limestone."

Jan 1, 1985