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By F. Nava-Alonso, E. Pérez-García, A. Uribe-Salas, J. C. Fuentes-Aceituno, A. A. González-Ibarra, E. N. Castillo-Ventureño

"Precious metals cannot easily be recovered from tellurides by the standard cyanidation process. This work assesses the cyanidation of synthetic samples of precious metals tellurides and explores some alternatives for the leaching of these species (i.e. cyanidation in presence of lead nitrate and thiosulfate leaching). For this purpose, three chemical systems were studied: (1) cyanidation of silver telluride and the effect of lead (II) nitrate addition, (2) cyanidation at high alkalinity and high cyanide concentration of a gold-gold telluride sample containing tellurium and tellurium dioxide, and (3) thiosulfate leaching of silver telluride employing cupric sulfate as oxidant and EDTA as complexing agent for copper. Results showed that standard cyanidation dissolves 10.5% of silver from silver telluride in six hours, while with the addition of 100 mg/L lead increased the silver dissolution up to 100% in the same time. The standard cyanidation of the gold-gold telluride sample dissolves only metallic gold in six hours, while when cyanide concentration and pH were increased, gold and gold telluride were simultaneously dissolved. Finally, thiosulfate leaching dissolves 43.1% of silver from silver telluride in six hours.INTRODUCTION Precious metals tellurides are classified as refractory ores due to the difficulties associated with processing them by the standard cyanidation method. The increasing presence of gold/silver tellurides in some deposits around the world, specifically in Sonora, Mexico, requires new approaches to the cyanidation process, or the development of new leaching techniques. Treatments have been proposed for the recovery of gold and silver from their tellurides, including roasting, preoxidation, cyanidation with lead nitrate, and the use of leaching agents other than cyanide (Zhang, et al., 2010; Ellis and Deschenes, 2016). This work presents preliminary results of three options to recover precious metals from pure tellurides: the cyanidation of gold telluride at high cyanide concentration and high alkalinity, the addition of lead nitrate to the standard cyanidation process, and the use of sodium thiosulfate as leaching reagent."

Jan 1, 2017

By Keith C. Hendrick

"Metal prices are frequently the most critical and least predictable element in determining the profitability of mining operations. Short -term fluctuations can be offset in varying degrees by hedging or other market actions. Such solutions are not practical for the longer term, The paper investigates the nature and extent of metal price risks and evaluates methods to reduce them.IntroductionIt is management's responsibility to improve the odds by managing the-risks by identifying them clearly, assessing them accurately, minimizing them where possible-and, then, timing decision s success fully.In determining the profitability of current operations, preparing forward plan s or developing feasibility studies for new projects or expansions, pr ices are usually the most critical input. Being market determined rather than cost based, they can also be the most unpredictable As a result, commodity prices are frequently the greatest of all risk factors.Nature of Commodity PricesThe cyclical nature of commodity prices is well known. They are stable only when supply is in balance with demand and forecast to remain that way. An imbalance on either side of the equation can lead to a price reaction completely out of proportion to the actual or perceived surplus or shortage.This exaggeration arises through the cumulative effect of market forces. When the market senses an uptrend, consumers buy for the expected increase in activity. They also seek additional quantities for inventory before price s rise. Merchants defer spot sales anticipating higher price s, speculators go along for the same reason, and producers raise prices in response to demand. Events tend to confirm the expectation of each party and strengthen their reaction causing prices to move higher."

Jan 1, 1983

By Ali M. Ghazi, Ronald J. Goble, Lowell S. Whiteside

"Geerite (Cu1.6S) is a rhombohedral copper sulphide which occurs naturally in epitactic replacement of sphalerite; cell dimensions closely approximate those of the host sphalerite.Geerite-type structures can be produced by leaching digenite (Cu1.8S) in ferric sulphate solutions. X -ray diffract ion and electron microprobe studies indicate that eight metastable geeritetype structures can be produced, depending upon the concentration of f erric sulphate solution used and the duration of the each. Although compositions cluster on or near values observed for natural phases, optical properties indicate that we are dealing with polymorphs of these phases. Leaching of chalcocite (CU2Sj in dilute f erric sulphate solutions produces similar results. In contrast, leaching of chalcocite in more concentrated solutions seems to produce true analogues of natural minerals.During froth flotation, sphalerite is activated with a monolayer of floatable copper sulphide with the composition, CuS, of the mineral covellite. However, covellite is not significantly more floatable than sphalerite, and has an incompatible structure because of the presence of covalently-bonded atoms of sulphur. Leaching ofdigenite was used to produce a polymorph of covellite with a geerite-type structure, compatible with that of sphalerite. This polymorph has a flotational behaviour similar to copper-activated sphalerite, suggesting that the monolayer has a geerite-type CuS structure. IntroductionIn an ideal close-packed sulphide structure the distance between sulphur layers, D, is equal to 2R 2/3, where R is the radius of the sulphur atoms. In sulphides with covalently-bonded sulphur layers, such as covellite (Fig. I), D will be an average of the number of covalentl y-bonded and close-packed sulphur layers, weighted as to the relative number of each type of layer. Both D and R are spacings which are readily identifiable structurally and on X-ray diffraction patterns. Goblel has shown that for copper-iron sulphides with metal-to-sulphur ratios between 0 and 2 and copper-to-total metal ratio s between 113 and I there are strong correlations between composition and measured D and R distances (Fig. 2). D can be represented by a single empirical equation relating interlayer spacing to composition; R must be represented by three equations relating the radius of sulphur atoms to composition. One of these equations (R, in Fig. 2) represents ideal close-packed behaviour, the other two represent sulphur radii greater than (R1) or less than (Rh) the ideal."

Jan 1, 1988

By D. C. Carter, J. P. Anderle

"Exploration drilling of evaporite sequences in eastern Canada has undergone significant changes in equipment, techniques and philosophy since the early 1970s. The result has been the recovery of full-size cores from properly conditioned and stabilized holes, high quality open hole geophysical logs, and high quality metallurgical samples. The majority of modifications have resulted from the necessity to preserve the integrity of the evaporite deposit, and thus ensure the potential development, combined with the need for cost-effective high quality information. This is particularly evident in the priority placed on the development of non-erosive drilling fluids, casing and cementing procedures. The results are applicable to diamond drilling exploration of evaporite deposits anywhere in the world.IntroductionThe majority of current technical and scientific literature and expertise available on such subjects as drilling fluids or cementing procedures is applicable to large diameter, deep (several thousand metres) oil-field type drilling . The differences between oil-field drilling and wire-line core diamond-drilling are dramatic: large diameter, deep holes drilled with a low rpm tricone bit using large volumes of fluid pumped through a large annulus versus small diameter, shallow (less than 600 m) holes drilled with a high rpm diamond-set core bit using small volumes of fluid pumped through a small annulus. Exploration drilling of evaporite sequences in eastern Canada in the early I970s was conducted using oil-field equipment and techniques to complete holes of moderate (1000 m to 1500 m) depth . The prohibitive cost of these operations has necessitated that subsequent exploration drilling employs modified diamond-drilling equipment and techniques developed as part of a transition away from oilfield methodology. The result has been full size core, recovery approaching 1000/0 and the ability to run open hole geophysical logs; a combination of factors enhancing the collection of high quality information (Carter, I989a)."

Jan 1, 1990

By E. A. Cleveland

A glance at the map discloses the fact that the Pacific Great Eastern railway either traverses or crosses some of the most important rivers of the province: the Squamish with its branches the Stawamus, Mamquam and Cheakamus; and the Green, Lillooet, Birkenhead, Fraser and Quesnel rivers. Each of these and some of their tributary streams, having their ?sources and upper reaches in the higher altitudes in regions of abundant snowfall, is capable in greater or less degree of furnishing water under suitable heads for the economic production of power. Beginning at its present terminus at Squamish the railway has the only hydro-electric development within its territory among the whole list of streams mentioned. A 225 horsepower installation at the edge of the East branch of the Squamish river, using water from Stawamus river, a branch of the former, under a head of 418 feet, is a modest beginning. Two or three additional sites, where water may be used under somewhat similar heads, may be found on this little stream. Next above Squamish, along the route of the railway, is the Mamquam, a long tributary of the Squamish from the eastern slopes. It has a drainage area of something like 130 square miles with widely varying discharges of from less than 50 to about 14,000 cubic feet per second. The preliminary investigations so far have disclosed no suitable storage sites, so the Mamquam may be regarded as a small continuous power stream - probably less than 1000 horsepower.

Jan 1, 1925

By M. R. Coffin

Since the plant startup in 1972, the leaching and jarosite precipitation circuits at the zinc plant of the Kidd Metallurgical Division have been reconfigured several times to improve overall performance, and/or to respond to market conditions. For the most part, the circuit changes have been driven by two market factors: the price of zinc and the price of silver. Until recently, circuit modifications undertaken to improve zinc extraction and recovery came at the expense of silver recovery, and vice versa. In 2004, the plant was modified once again to produce a precious metals-bearing residue, but additional leaching circuits were added to ensure that zinc extraction and recovery did not suffer as a consequence. The development of the zinc plant of the Kidd Metallurgical Division is updated in this paper, with a focus on the recent circuit modifications and associated control strategies that were implemented to maximize zinc and precious metals recoveries, and control the quality of the jarosite residue.

Jan 1, 2006

By N. Bakhshizadeh

In this investigation, the aging effect on creep behavior of A12024-10%SiC composite fabricated by powder metallurgy was studied. P/M bars were manufactured by hot powder extrusion method at 450°C with a ratio of 16 to 1. Creep specimens were over-aged at 187 ºC for 43 h. It was found that almost full density composite with relatively homogenous distribution of reinforcing particles throughout the aluminum alloy matrix could be attained by direct powder extrusion process. Creep tests were conducted at temperatures from 275 to 325°C under stresses from 25 to 60 MPa. The analysis of the creep mechanism determined that dislocation glide was the predominant mechanism of plastic deformation. The activation energy of the creep process was found to be higher than that of lattice self-diffusion in pure aluminum.

Jan 1, 2007

By J. E. Nesset

"This paper discusses the importance of considering residence time distribution (RTD) in the design of flotation and mixing circuits and in the analysis of operating problems. The experiences and successes of Brunswick Mining in this area are covered and include: the development of a practical RTD measurement technique using pulp conductivity, baffle installation to improve the RTD of existing process equipment, and the method in which RTD considerations have been used to design the newest flotation and conditioning operations. IntroductionThe use of residence time distributions (RTDs) in the design and analysis of unit operations is well understood by the chemical engineering profession in while mineral processing engineers have tended to rely on empirical and rule-of-thumb factors. For example, in scale up from laboratory and pilot test results to full size flotation plant design, empirical rule s are often used to establish residence time and number of cells in the bank. Coleman suggests a factor of at least 2, and up to 5 for gold ores, be applied to laboratory determined flotation times. This is further illustrated in Table I, taken from Denver equipment.The number of cells in series to achieve the required retention time while minimizing short-circuiting has generated a variety of conclusions (Table 2). Obviously there is less than complete agreement on the subject. Young notes that a clear difference of opinion has emerged and cites as extremes, (i) the publications of Outokumpum showing unimpaired recovery for its largest machines (38 m3) compared to equivalent retention times for numerous smaller machines, and (ii) the experiences of Eastern European countries where the practice is to install banks of 30 unit s or more, operating in series, often with unit retention times of only a fraction of a minute.The empirical factors used by engineers presumably account for other than tested feed conditions, inefficiencies in large continuous machines, inevitable day-to-day circuit disruptions, gradual equipment deterioration and any other safety factor the engineer feels compelled to incorporate. An understanding of RTD concepts and techniques should help the practicing mineral engineer to develop more soundly based factors. This paper relates the experiences of Brunswick Mining in using RTD techniques in the unit operations of flotation and mixing."

Jan 1, 1988

By Bradford P. Simser

Increasingly sophisticated rock mechanic tools are becoming more and more available for today?s ground control specialist. However many problems are still beyond our ability to explicitly calculate or measure. There is often a gap between the ?art? and the ?science? of rock mechanics. This paper focuses more on the ?art?, giving relatively simple examples of underground observations and micro-seismic records to help explain ground control issues. Ground support techniques such as in cycle shotcrete with high pressure water scaling, mesh and bolting, pumpable resin bolts/cablebolting, and yielding bolts with load spreading straps are discussed. The use of primary/secondary type blasthole sequences in moderate to high stress situations is also discussed with several examples of the micro-seismic response to the stoping. Relatively erratic geology with high material strength contrasts is currently being mined with blasthole methods at Nickel Rim South. Although the mine is still in its? ?early? days, over 1 million tonnes has been extracted and some empirical experience is highlighted with potential longer term issues also being discussed.

Oct 1, 2010

By Lanny Pasternak

"This article is directed at plant production, engineering and maintenance personnel. Seldom does any industrial operation take the time to study the costs involved in the generation of what is probably their most expensive plant utility energy source.IntroductionIn the typical industrial plant in Canada, a 200 hp, 900 cfm, air compressor costs about $60,000* per year to operate (Fig. 1). In 1989 when BC Hydro embarked on their industrial energy management program Airflow Energy Ltd. were asked to spearhead the “Efficiency Compressed Air” portion of that program with a mandate to perform onsite overview surveys and physical hands-on testing of some 300 selected industrial plants throughout British Columbia for compressor efficiencies and wasteful air leaks (Fig. 2). The program duration lasted until 1995, during which time a tremendous amount of data were amassed relating to equipment types, clients’ operating habits, end-use applications and operating costs.During the past six years, Airflow Energy also performed somewhat similar surveys but on a smaller scale in Alberta, Ontario, the United States and the Republic of China. It was no surprise to find some inherent equipment concerns related to efficiency as well as neglected energy wasteful air leaks, so British Columbia was not alone and the problems appear somewhat universal."

Jan 1, 1996

By Horace Freeman

The sulphur consumed in Canadian pulp mills and acid plants is worth approximately three million dollars annually and amounts to one hundred and fifty thousand long tons, all of which is imported from the United States. Concurrently with a decline in the value of newsprint there has been a gradual increase in the price of this raw material. Most pulp mills in Canada are situated within reasonable distance of domestic pyrite deposits; nevertheless it has not yet been found possible to mine these deposits and utilize the contained sulphur in competition with the imported material. It is the purpose of this paper to elucidate the reasons therefor, and to describe? a commercial-scale experiment undertaken with the object of introducing a native raw material into the Canadian pulp industry on the purely economic basis. Reasons for the Preferred use of Sulphur The known sulphur deposits in the United States are very large, so that at least a twenty-year supply of this material is assured. It is recovered cheaply and in pure condition. Although large deposits of pyrite are known in Canada, nothing has yet been developed to compare in size, cost of mining, or purity with the United States material. It has been necessary to handle and transport more than two tons of pyrite to equal a ton of sulphur.

Jan 1, 1930

By David J. T. Carson

"The metalliferous deposits of Vancouver Island have generally been assigned to the Mesozoic ""Coast Range Orogeny."" However, a metallogenic study by the writer has revealed that several important classes are early or middle Tertiary. Included are porphyry coppers, and gold-quartz, arsenic and copper-arsenic veins.The porphyry coppers and many gold-quartz veins are within and adjacent to Oligocene-Eocene quartz diorite intrusive complexes. Arsenic and copper-arsenic veins have a close spatial relationship to sills and laccoliths of Oligocene dacite porphyry which intrude the late Cretaceous Nanaimo Group.Other deposits of demonstrable Tertiary age include a molybdenum stockwork related to a relatively potassic Eocene plug and a few small copper-skarn occurrences. Some copper stockworks and a mercury deposit are probably also Tertiary.The copper deposits of previously recognized Tertiary age are those of the Sooke area that occur in Eocene basalts and Oligocene gabbros."

Jan 1, 1969

By W. N. Wallinger

The mine and concentrator of Cyprus Anvil Mining Corporation are situated in south-central Yukon, some 120 miles north of Whitehorse. The large lead-zinc concentrator employs conventional crushing and grinding , followed by differential flotation, to produce selective lead and zinc concentrates, as well as a mixed lead-zinc (bulk) concentrate. Since the commencement of operations in 1969, the concentrator has undergone expansions and modifications which have increased the capacity to 10,000 tons per day, and afforded some metallurgical improvements.

Jan 1, 1978

By E. Swartzman

"IntroductionGENERALLY, the necessity for mining coals of higher impurity content, the drive for lower costs by intensive mine mechanization, changing market requirements, and the increasing competition of oil and natural gas, have continued to result in an upward rise in coal preparation, and have necessitated a more intensive study of coal preparation problems.Increasing adoption of •continuous mining equipment, for example, is introducing new problems in coal preparation. Limited experimental work in the United States (1) shows that the effect of the continuous miner on size distribution varies with the characteristics of the seam. In some seams, the fines problem is lessened, in others it is greatly aggravated. Generally there is a decrease in the relative amount of the top sizes (plus 2 in.) and a substantial increase in the intermediate sizes (down to about 1/8 in.). Contrary to expected results•, where continuous miners with vertical-moving cutting heads are used, an increase in impurities in the slack sizes does not necessarily occur where draw-slate is taken. This is because the draw-slate tends to be kicked out in lump form. However, if a seam contains bands •and lenses of impurities they are bound to be in the mined product."

Jan 1, 1952

By H. Arima

The Akita Zinc Company is the only refinery which produces hematite from the iron content in the zinc leach residue. The Akita Hematite Process consists of five stages, which are SO2 pressure leaching, the first neutralization stage, the de-arsenic process, the second neutralization stage and pressure hematite precipitation. In order to strengthen its cost competitiveness and stabilize its operation, the Akita Hematite Process has been modified continuously. Most recently, two process modifications were carried out. The first was an improved ability to maintain a lower arsenic concentration in the de-arsenic process, and the second was an increased throughput in the hematite precipitation autoclave. The details of these recent changes in the Akita Hematite Process are presented in this paper.

Jan 1, 2006

By Gang Mei, Nengxiong Xu, Yanlin Zhang

After open-pit mining finishes, an iron mine with steeply inclined ore-bodies will generally transform to underground mining. Non-pillar sublevel caving method, with horizontal slice mining from up to down, is commonly used for mining deep ore-bodies under the open-pit bottom. As horizontal slice mining proceeds, a gradually enlarging goaf will be formed under the open-pit bottom, the rocks surrounding the handing and heading sides of the goaf will collapse continuously, and then these results in rock-mass failure with large deformation and displacement in the open-pit slope. Based on FLAC3D, a modeling approach to predict pit slope deformation and failure induced by transitioning open-pit to underground mining is proposed in this paper. This method mainly consists of three procedures of modeling, i.e., mining modeling, landslide modeling, and filling modeling, of which landslide modeling is the core of the proposed approach. In the procedures of modeling with FLAC3D, iteration non-convergence is taken as a local failure criterion of pit slope. When iteration calculation cannot converge, the sliding modeling will start by deleting some elements with large displacements, and finish until convergence. Before modeling landslide, several displacement contours of rock-masses in the pit slope are searched out, and each contour is an approximate possible sliding surface of the open-pit slope. From these contours, the most proper one is selected as the slope sliding surface by using the iteration calculation convergence and minimum element deletion as the judgment condition. Landslide modeling is then realized by removing the elements outside the slope sliding surface. Finally, to demonstrate the effectiveness, the proposed approach is used to simulate the process of open-pit to underground mining at Yanqianshan Iron Mine, and to predict the deformation and failure characteristics of open-pit slope during underground mining. The case study results show that: the prediction of the slope stability determined by using our method is consistent with that calculated by using the limit equilibrium methods.

Jan 1, 2015

By Miguel A. Cuba

Trends in the mean and/or variance are a longstanding challenge in mineral resource modeling. Geologic modeling and/or grade domaining are often employed to account for heterogeneities in mineral grades; however, this is only practical up to a certain point since the number of data available for reliable model construction can be severely reduced. In such cases, trends remain present in certain geologic/grade domains and directly impact the modeling methodology; the trend must either be handled explicitly or a suitable approach is adopted to implicitly account for it. This is highly dependent on understanding the source of the trend. We propose an approach that detects the source of non-stationarity, which is based on quantifying the impact of non-stationarity in the mean and the variance via the semivariogram. By expanding the methodof- moments approximation of the semivariogram, we decompose the experimental semivariogram is into three terms: 1) trend in mean component, 2) trend in variance component and 3) stationary component. We can then assess the source of trend by calculating the contribution of each component at every lag. Two cases are presented to illustrate this tool. Firstly, a synthetic reference model is simulated and different trend patterns are added; the influence of these patterns in the experimental semivariogram calculation are analyzed and discussed. Secondly, a real dataset is considered where the impact due to the presence of trends in the mean and variance are assessed. The results of this paper reveal the semivariogram to be a tremendously powerful tool in determining the source of the trend. This insight may be useful in the selection of a suitable modeling approach for resource estimation.

Oct 1, 2009

By L. Vu, V. Popov, J. Beland, R. Darling

"The Ferderber gold deposit is of Archean age. It consists of a series of gold-bearing quartz lenses within a shear zone that crosscuts the central part of the quartz dioritic Bourlamaque batholith. On average, this zone strikes N70E and dips 65SE. The Ferderber shear zone, which hosts the ore lenses, has been affected by a succession of tectonic events. A possible early period of brittle shear, accompanied by the formation of quartz lenses, resulted from strike slip movement along the zone. These early quartz veins were subsequently folded and boudinaged during reverse movement that accompanied a prolonged period of ductile shear. More quartz veins were emplaced in the shear zone at this time; these were also deformed by the thrusting. The latest tectonic event to affect the shear zone was a period of brittle fracture.Early dextral strike-slip movement on the shear zone is suggested by the local occurrence of Riedel shears, the preferred association of ore with east-northeast oriented segments of the zone, and by the apparent en echelon arrangement of some ore lenses. The most important event, a reverse movement, is indicatedby the attitudesoffoliation, folds, boudins, COS tectonites and slip planes. The late brittle fracturing formed narrow gouge filled faults, locally flanked by brecciazones, whichrun generally within and parallel to the shear zone, and also conjugate fractures that crosscut the zone.The Ferderber and six other adjacent gold deposits were formed in a structural regime dominated by a generally horizontal north-south regional compression. The Y axis of the strain ellipsoid is east-west and varies from horizontal to a plunge of 25 0 w."

Jan 1, 1987

By F. Flores

With the World Summit for Sustainable Development planned for 2002 in mind, nine of the world's largest mining companies decided to initiate a project to examine the role of the minerals sector in contributing to sustainable development, and how that contribution could be increased ? the Mining, Minerals and Sustainable Development Project (MMSD). This project assumed from the start that sustainable development could provide a useful framework to guide the minerals sector which main goal was integrating economic activity with environmental integrity, social concerns, and effective governance systems. The broad steps of MMSD project strategy can be grouped into four major categories: increase understanding of sustainable development; create organizational-level policies and management systems for implementing the principles of sustainable development; collaborate with others with common interests to take joint steps towards sustainable development, and; increase our ability to work towards sustainable development at the local, national, and global levels. In opinion of the article's author, to go ahead with the MMSD strategy and achieving the sustainable development objectives, it is necessary to consider the concept of self-organization, fundamental of the emergent new scientific paradigm, and the consequent epistemology and values that conform a supporting culture for sustainable development.

Jan 1, 2007

By Anthony J. Deevy

"The Magino gold mine is located 45 km northeast of Wawa, Ontario. There was limited gold production in the late thirties. The present operation was officially opened in October 1988 and produced gold until September 1992. It was a 635 tonnes per day, decline-accessed mine, with ore coming from several small blast hole and shrinkage stopes.The host for the gold is the Webb Lake granodiorite stock which was intruded into the Goudreau Lake Deformation Zone. This east-northeast-striking deformation zone overprints the generally east-west- striking isoclinally folded metavolcanic and metasedimentary rocks, which make up the east end of the Michipicoten greenstone belt. The ore-shoots are controlled by dextral delatancy associated with the Goudreau Lake Deformation Zone. Shearing, bleaching and silicification accompanied the gold emplacement. IntroductionThe following is a general information paper on the Magino gold mine which is located 45 km- northeast of Wawa toward the east end of the Michipicoten greenstone belt. This paper summarizes the discovery, exploration and development history of the deposit. The geological characteristics are described, including regional geological setting, local mine geology, mineralization, alteration and structural history. The mining methods and the contribution of the geological staff to the successful development and mining of the gold deposit are also mentioned."

Jan 1, 1994