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By Kenji Koga

In order to derive the population distribution of gold nanoparticle morphologies as a function of size, highresolution electron microscopic (HREM) observations and structural analyses were done for over 4000 particles (3-18 nm) grown by an inert gas aggregation (IGA) source using helium. To obtain structural features threedimensionally and not to skip high-contrast images, twenty photos were taken for each particle by changing tilting angle of a specimen holder in combination with the through-focus procedure. For the reliable structural determinations, HREM images and their tilting sequences were directly compared with multislice-simulation results for icosahedral, decahedral and face-centered cubic morphologies, and finally the population distribution of each morphology was obtained as a function of size. In the present sample, icosahedral particles were dominantly populated over the whole observed size range and decahedral particles with non-spherical truncated bi-pyramid shape were secondly dominant. Even though a large number of sampling has been done, few crystalline particles were observed.

Oct 1, 2003

By C. Derek Martin

"Predicting the ground response for tunnels in weak shales remains challenging. Predicting the ground response is challenged by difficulties in characterising the material, and our ability to predict deformations that are driven by coupled hydromechanical processes, when this material yields. The techniques that are used for characterizing weak shales are reviewed, and three case histories are examined that demonstrate the behaviour of these weak rocks during tunnelling. A general framework is provided for assessing the squeezing potential for weak shales.1 INTRODUCTIONGeologically, shale is an argillaceous fine-grained sedimentary rock that forms from the compaction of silt and clay-size mineral particles commonly referred to as ""mud"". Because of this grain size, the material is generically classed as Mudstone (Figure 1). Shale is distinguished from other mudstones because it is made up of many thin layers (laminated) and readily splits into thin pieces along the laminations (fissile). While the geological classification of shale appears straightforward, the classification for engineering purposes is often confusing. Underwood (l967) provided the first description of shale that made the distinction between “soil-like” compaction shales and “rock-like ""cemented"" shales. He coined the term ‘clay shale’ to capture the characteristics of hard clay yet recognizing its origin as a shale. In this paper weak shale is synonymous with clay shale and have strengths that typically range from R1 to R2 (1 to 25 MPa). Characterising these materials draws on methods from both soil and rock mechanics."

Jan 1, 2015

By J. M. Simard, S. Morissette, P. Coursol, P. Mackey

A new, powerful model is presented that focuses on plant logistics and scheduling aspects of the smelting, converting, fire refining and casting operations at the Horne smelter. This plant complex is the largest custom copper smelter in North America. It handles a wide range of feeds and utilizes a number of proprietary continuous and batch technologies that require good scheduling in order to maximize plant capacity and efficiency. The present model was developed by Xstrata Process Support, in collaboration with the Horne smelter, and uses the Arena® software to evaluate the impact of a number of plant variables on the annual copper capacity of the plant. Model development was carried out by Xstrata Process Support, in collaboration with the Horne smelter, through the effective combination of process chemistry knowledge and detailed knowledge of the plant operation (including all material flows and transfers, as well as information such as operating on-line times, plant stoppages and also scheduled and unscheduled maintenance activities). A number of case studies were then examined, including the impact of anode furnace and casting cycle times on annual copper capacity and the impact of a one-crane mode of operation in the converter aisle, which normally operates with two cranes in service. The model predictions were found to match actual plant results very well. The present modelling of plant logistics and the scheduling aspects were found to add important dimensions at the plant with regard to projections of the real-life plant capacity. As demonstrated in the present case, this type of model and application can have a significant impact on optimizing operations at a given plant. This impact is particularly important in the current market environment, where emphasis is on maximizing plant output and lowering costs. These models can help yield the easily obtained gains that are clearly desirable in these times. Xstrata Process Support has developed Arena models for other operations and is available to explore new applications for a win-win situation at other plants, including mines and concentrator operations.

Jan 1, 2009

By Hans von Michaelis

"INTRODUCTIONThe renaissance in gold and silver recovery technology has continued to unfold and it is appropriate to review some of the useful new technologies as well as try to identify some of the industry's future needs and frontiers.The remarkable strengthening in the US dollar has resulted in a relatively low gold price in US Dollars of around $310/oz at the time of writing and silver at $6.25/oz. This general softening in the dollar prices and the recent confusion as to environmental compatibility of cyanidation tailings and effluents, has led to a slowdown in announcements of new operations. Another reason for the slackening off in the USA is that in the past few years a large part of the capital has come from oi I and gas companies that now seem to be losing interest in mineral ventures, and foreign investors for whom the dollar is becoming out of reach. In the author's opinion this represents an unprecedented window of opportunity.Elsewhere in the world where local currencies have weakened, the price of gold is at or close to its all time high.For example, in South African Rands, the gold price was R571.00/oz when the rand was US$1.47 and the gold price reached US$800. Now at US $309/oz and with the Rand at US$0.51 = Rl .00, the local gold price is R600. The price of si Iver in Mexican pesos is not much less than it was when silver reached US$50/oz. Gold, and silver prices in local currencies outside North America are still buovant and at levels where additional investment in new projects is more encouraging.Even in Canada where the dollar is worth about US$0. 75, this provides a smaller but significant cushion compared with US operations. Considering the present strength of the US dollar and even the Canadian dollar relative to many other gold producing countries, there should be significant investment opportunities at today's prices. Mining companies have started to descend on Brazil, for example, where in a matter of just a few years annual gold production has increased from 10 to 70 tons. In South Africa, a Canadian company backed by Swiss financing has been able to take over a Witwatersrand gold mining operation and is installing a huge new tailin9s retreatment plant to process about 1 million tons per month of tailings."

Jan 1, 1985

By S. Nikolic, O. O. Kehinde-Philllps, O. T. Djamgouz, D. H. Rousell

"A bulk mining method is employed at the Lockerby mine resulting in the formation of large muck-piles. If these muckpiles remain in the stopes for some time they may agglomerate to the extent that the muck cannot be removed by a scooptram. A laboratory investigation was undertaken with sulphide material from the mine in order to detemine the time that oxidation begins and the flowability of the material as a f unction of several factors. The laboratory results are applied to the conditions in the muck-piles.The time of the beginning of oxidation of the material decreases as the sulphide composition, water content and availability of air increases. Oxidation is retarded by the addition of a copper sulphate solution instead of water. The unconfined yield force (strength} of the material increases with an increase in the sulphide composition, water content and time. The material ceases to be free-flowing before there is visible evidence of oxidation and this suggests that oxidation actually begins earlier and that agglomeration is also due to the capillary action of water.Broken ore should be removed from the stope prior to the time a muck-pile ceases to be free -flowing-perhaps as early as two days f or high-grade ore and 5 days f or low-grade ore. In order to control dust, 1.4 weight per cent of a 5 per cent solution of copper sulphate should be added 10 the muck-pile rather than water. This inhibits oxidation and increases the time that a muck-pile remains free-flowing."

Jan 1, 1984

By R. Simkus, J. K. Gowans

Polaris Operations, a Cominco Ltd. lead-zinc mine, is located on Little Cornwallis Island, Northwest Territories, at Latitude 75°23' N and Longitude 96°75' w. When the Polaris Mine went into operation in late 1981, it became the world's most northerly base metal mine.The Polaris Concentrator, housed in a unique process barge, is a basic lead-zinc concentrator where flotation is used to produce the lead and zinc concentrates.The paper describes the ""coarse lead"" flotation feature incorporated in the concentrator flowsheet and describes the start-up problems and continuing operation of this circuit.

Jan 1, 1984

By M. W. Lewis, J. Werner

Fluctuating metal prices, declining head grade, and increased operational costs are forcing many open pit mining companies to look to their balance sheets for significant cost reductions in order to remain competitive. Maintenance continues to represent a significant proportion of the total operating costs in the mining industry. Compared with the other major cost components of the mining process, very little effort has gone into maintenance optimization. The potential payoff from maintenance optimization on the cash cost of the commodity is enormous. A large percentage of these costs are incurred in unscheduled maintenance events, which typically cause serious disruptions to the production process. These maintenance-induced production losses can be a significant contributor to the overall operating costs. A structured proactive maintenance approach using the latest advances in technology can achieve dramatic cost reductions and productivity improvements. Remote condition monitoring systems are becoming increasingly commonplace and have the potential to identify problems prior to failure. Detection of equipment degradation prior to failure will enable repairs to be scheduled thereby reducing costs and interruptions to production. Remote condition monitoring technology has evolved rapidly in recent years, with a host of new tools becoming available to assist mine operators in improving their maintenance operations. These tools have capabilities such as remote real-time vital signs and performance monitoring, alarm/event handling, trend analysis, and maintenance workflow management. When these monitoring tools are used in conjunction with a mine management system, the vital signs data can be integrated and associated with maintenance history, predictive maintenance data, operational information, and geographical information. This integrated approach to the management of vital maintenance data will help shift the mobile equipment maintenance paradigm from reactive to proactive. This paper will introduce a proactive approach to the management of the maintenance process and the tools required to facilitate this process.

Jan 1, 2005

By R. T. Jones

"Technical publications in the field of mining and metallurgy have existed for a long time. Recent developments in electronic publishing on websites make it possible to disseminate information more widely and cost effectively than before. Professional societies have an opportunity to serve their members and their industry by publishing high-quality peer-reviewed papers on their websites as well as in printed form. Older publications can be scanned, and optical character recognition can be used to provide searchable text. Various business models exist around this process. This paper outlines the approach used by the Southern African Institute of Mining and Metallurgy (SAIMM) to provide free open access to their journal papers and conference proceedings, as well as the work being done by OneMine.org to collect technical papers from a number of international societies and make them available to subscribers via a large database. An approach is outlined that should be of benefit to authors, readers, and society at large.INTRODUCTIONGeorgius Agricola (1494-1555) was not the first writer on the subjects of mining and metallurgy, but is well known as the author of De Re Metallica (‘of things metallic’ or ‘on the nature of metals’), a book that documents and illustrates the observations he made in the course of his extensive travels in the 1500s. Agricola wrote extensively about mining methods and metallurgical processes that were in place in the Middle Ages. The original Latin version of De Re Metallica was published in 1556, the year after Agricola died. It was translated into English by Herbert Hoover, a mining engineer and later President of the United States, and his wife Lou Henry Hoover, a geologist and classicist. The English version of De Re Metallica was published in 1912."

Jan 1, 2012

By P. Choquet, F. Miller

"The development and testing of a simple low-cost gauge for measurement of tension in a cable bolt grouted in a borehole are presented. Its principle is based on a resistance wire which is wound on a 70 cm length into the spiral grooves of the wire strand cable bolt. Readings are then taken by a robust automatic data logger with a several day autonomy or by a portable readout. In order to have a complete profile of tension along the cable bolt, a number of tension gauges can be installed along its length.This paper provides a description of the development and laboratory calibration of the tension gauge and addresses the two modes of loading for a cable bolt in a rock mass, namely pure tension and shearing at a joint location.In the second part of the paper, four field tests in underground and open pit mines are reported. The first test was used to substantially modify both the gauge and the readout unit principles while the other tests which are still on-going show a very satisfactory behaviour of the modified version of the tension gauge. IntroductionCable-bolting is often used as ground support in Canadian mines for a variety of applications. In underground mines, cable bolts can be installed vertically at the back of cut and fill stopes or in an inclined fashion in the walls of large open stopes. Alternatively, cable bolts at Mines Gaspe (Noranda Inc.) are used in a fan-shaped pattern from a drill drift to stabilize the inclined roof in 25 m wide open stapes. This new application oriented our research efforts toward the design of a novel instrumentation to monitor the efficiency of most commonly used 5/8-inch cable bolts."

Jan 1, 1988

By L. D. Haig

"The Texada Mill is a unique iron operation producing High Grade sinter iron concentrate and a by-product copper, gold, silver concentrate. The plant is complex and extremely flexible to handle the many varieties of ore. Two iron concentrates are made and blended. A coarse iron concentrate from primary grinding and a fine concentrate after rougher flotation to remove all the sulphides.All the tailings from iron processing are collected, dewatered, reground and floated for additional copper recovery.The entire milling operation has been carried out in all sea water for seven years and mixtures of sea, fresh, and reclaimed water for ten years prior to that.A very stable float results from the use of sea water at the natural pH8. Reagent Consumption is lower and Metallic Corrosion of mill liners and grinding media is actually less than local fresh water or mixtures of fresh and sea water.Marine growth in pipe lines can be periodically removed by violently bubbling high pressure air up through the water filled mains.Location:Texada Mines is located on tide water on the west side of Texada Island 100 miles northwest of Vancouver, B. C.The Island is served by a 30 car ferry, tug and barge and a scheduled air service from Vancouver to a company maintained air strip near the mine.The climate is moderate with about 30 inches of rain during the winter and relatively dry summers."

Jan 1, 1974

By John Stubbles

Data are presented on the global warming issue to reinforce the decision by the U.S to reject the Kyoto protocol. The evidence that CO2 is a problem rather than a benefit is inconclusive and will be discussed in this paper. Nevertheless, for economic reasons alone, the US steel industry will continue to minimize CO2 emissions (and the release of real pollutants) per ton of steel through energy reduction programs. However, relative to inevitable increases in absolute CO2 emissions from the utility industry and the transportation sector, future reductions by the steel industry will be inconsequential in the "big picture."

Jan 1, 2004

By J. A. Abols, P. M. Grady

Recovery via gravity is one of the oldest mineral processing methods available. Unfortunately, the use of gravity techniques for gold recovery has been in decline for the past century as more effective chemical processes such as flotation and leach/CIP have been developed. Recently, with the push towards more sustainable environmental outcomes, the benefits of gravity separation have become more apparent. While gravity as a unit process is not usually capable of achieving as high a recovery as flotation or whole ore cyanidation, a combination of gravity devices alone or in conjunction with these processes can offer significant advantages to the operator. This paper reviews the range of gravity devices available, their application and the results that can be achieved by maximizing gravity through the use of a combination of gravity recovery devices. Three case studies are provided.

Jan 1, 2005

Risk management has taken on renewed vigor since the economic crisis of the late 2000s. The resources of governments, individuals, and corporations are being stretched to a point where only the most promising projects move forward. Risk management is a crucial part of the decision making process, yet it remains a broad term that includes disciplines from engineering to finance. A collaborative effort will be necessary to ensure that the most auspicious and appropriate projects are the ones moving forward. Risk management can be quantified to an extent by comparing the likelihood of an instance with the result of consequence of the instance occurring. In this manner it is possible to assign risk factors to instances and ultimately, begin to associate monetary value to the instance. Carbon sequestration is an emerging field that has a number of unique challenges. Risk management and mitigation must be an integral part of the overall picture. This begins with the planning and design phase, continues through implementation and production, site closure, and does not cease until termination of liability. The ability of carbon sequestration projects to successfully assess, mitigate, and recover from leaks will be a decisive characteristic of overall success. The costs of mitigation and failure will need to be analyzed on a test level, but will still need to be reliable enough to extrapolate to a commercial level operation. This paper will build a risk management profile based on case studies and field tests in Tennessee and Virginia. These tests are scheduled to commence in late 2013 and consist of small-scale injection tests in unconventional storage reservoirs with an emphasis on enhanced coalbed methane (ECBM) recovery and enhanced gas recovery. The ultimate goal will be to provide a clear and concise direction to move carbon sequestration from the test phase to commercial scale. While it is necessary from a risk management perspective to analyze all risk points, the scope of this paper will focus on pre-injection risk assessment for carbon dioxide (CO2) leakage potential. Despite the differences between the two tests, CBM compared to shale among other differences, a framework for analysis and mitigation can be developed pertaining to leakage risk. The probability of each type of failure will be assessed and analyzed, and plans to mitigate or reduce these risks will be reviewed.

Aug 1, 2013

By Balakrishnan Nanthakumar, Marek Pawlik, Dennis Grimm

"The anionic flotation of a high-iron phosphate ore from Agrium - Kapuskasing Phosphate Operations was investigated through batch flotation tests in the presence of soda ash. The flotation data were supplemented by titration of the flotation pulp with soda ash, analysis of process water chemistry, and determination of the mineralogical composition of the ore. The results of lab tests were applied to the flotation circuit design allowing the flotation plant to efficiently process problematic ores. Process control measures (pH, conductivity) were also developed.Calcium cations and sulfate anions were identified as the dominant ions present in the process water when the difficult-to-process ores are beneficiated in the flotation plant. The concentrations of calcium and sulfate ions were consistent with the presence of a small amount of a calcium sulfate mineral in the ore although an oxidation/weathering process of iron sulfide minerals present in the ore could also be responsible for the observed water chemistry and subsequent flotation problems with the ores. The latter possibility suggests that the long-term stockpiling of such ores may have a highly negative impact on the flotation process.The role of soda ash in the flotation circuit is to precipitate metal cations from the pulp thus allowing the tall oil-based collector to selectively interact with the phosphate components.INTRODUCTIONPhosphorus minerals are the main source of this element for the production of fertilizers, and the froth flotation process is the most important technology for beneficiating phosphate ores. The flotation concentrate from Agrium-Kapuskasing Phosphate Operations (KPO) is transported to Redwater Fertilizer Operations in Alberta (also operated by Agrium) where the phosphate concentrate is converted into a phosphate fertilizer and other important chemical products. The KPO phosphate ores differ widely in mineralogy and phosphate grades, and are broadly divided on-site into three classes. The easy-to-float A-type ores do not pose any major flotation problems, but the B-type and “marginal” ores, which are quite common in the KPO igneous phosphate deposit, are not always readily-floatable using the current reagent suites and process parameters (pulp density, feed particle size, pH). In fact, marginal ores are presently considered impossible to process by flotation. A-type ores contain normally more than 15% P2O5 and less than 8% ferric oxide equivalent (Fe2O3). B-type ores are approximately of the same P2O5 grades as A-type ores but their iron content may reach 30% Fe2O3. Any material containing less than 15% P2O5 is rejected as waste rock."

Jan 1, 2008

By Claude Deveau

"With ever decreasing feed grades, finer mineralogy and increased demand for product, it became obvious that a major step in equipment performance was required to reduce operating costs and increase production. Offsite testwork indicated that a Centrifugal separator was capable of recovering fine tantalum and that the newly developed C Series Falcon concentrator would be capable of replacing many pieces of aging equipment and provide improved performance. Further investigation led to the rental and the purchase of a Falcon C20 concentrator followed by a C10 to maximize circuit performance.Falcon Concentrators Inc’ s practice of working with the customer mirrors Tantalum Mining Corporation of Canada’s (Tanco) philosophy of continuous product development. This synergy honed valve design for continuous operation in a highly abrasive ore environment.Tanco has recently purchased two more Falcon concentrators for the recovery of additional tantalum from its spodumene circuit. These new units have additional user friendly operating features partially based on developments made at Tanco.The Falcon C Series units have enabled Tanco to maximize recovery of tantalum that was otherwise lost while using the original conventional gravity circuit."

Jan 1, 2000

By J. A. McLennan

Geological uncertainty is an unavoidable characteristic of all mining projects since only limited information is available from sampling. Mine planning and development decisions with significant economic consequences are made when the geological heterogeneity is inherently uncertain. Geostatistical simulation is preferred over kriging because the methodology provides alternative property realizations that can be combined into a model of geological uncertainty. Geological uncertainty can be transferred into production uncertainty, which can help characterize the economic risk of the project. This paper presents a case study for the Pogo property, being prepared for development near Fairbanks, Alaska. The exact dimensions, grades and production predictions have been modified; however, the methodology is illustrative. The geostatistical methodology consists of (1) assembling the relevant drillhole data and establishing a suitable coordinate system, (2) calculating the target distribution, (3) creating a model of spatial correlation, (4) generating multiple realizations at a small scale and (5) linearly averaging all the realizations to the chosen selective mining unit (SMU) support size. The geostatistical model is then used to calculate production uncertainty.

May 1, 2004

"The measurement of error in assays collected as part of a mineral exploration program or mining operation historically has been undertaken in a variety of ways. Different parameters have been used to describe the magnitude of relative error, and each of these parameters is related to the standard measure of relative error, the coefficient of variation. Calculation of the coefficient of variation can be undertaken in a variety of ways; however, only one produces unbiased estimates of measurement error: the root mean square coefficient of variation calculated from the individual coefficients of variation.Thompson and Howarth’s error analysis approach has also been used to describe measurement error. However, because this approach utilizes a regression line to describe error, it provides a substantially different measure of error than the root mean square coefficient of variation. Furthermore, because regression is used, Thompson and Howarth’s results should only be used for estimating error in individual samples, and not for describing the average error in a data set. As a result, Thompson and Howarth’s results should not be used to determine the magnitudes of component errors introduced during geochemical sampling, preparation, and analysis.Finally, the standard error on the coefficient of variation is derived, and it is shown that very poor estimates of relative error are obtained from duplicate data. As a result, geoscientists seeking to determine the average relative error in a data set should use a very large number of duplicate samples to make this estimate, particularly if the average relative error is large."

Jan 1, 2007

By A. T. Robles, L. Buckingham

"When certain gold ores containing pyrite, graphite, humates and fumates or other organic compounds which are possibly adsorbed on clay minerals are treated with aqueous solution of alkali metal cyanide, the aurocyanide complex which forms is adsorbed by these ""pregrobbing"" species in the ore. Dissolution of gold proceeds until chemical equilibrium is attained between the cyanide complex adsorbed by the ore and in solution.Sodium lauryl sulfate (SLS) may be used to decrease the adsorptive activity of the prerobbing species in the ore. It has successfully improved recovery at Holt-McDermott Mine and is highly biodegradable.INTRODUCTION Precious metal-bearing ores containing preg-robbing species are poorly amenable to standard cyanidation techniques. The ""preg-robbing"" impurities with which they are associated tend to adsorb the gold cyanide complexes and carry them through the circuit to the tailings. Also, gold may be associated with these impurities in the ore and not be leached by the cyanide complexing agents used in conventional cyanidation techniques.Methods for dealing with the problem of preg-robbinq impurities in gold ores are:Carbon-in-Leach (CIL), in which granular activated carbon is added to compete with preg-robbing species for the gold cyanide complexes. This process can improve gold recovery in mildly preg-robbing ores especially when fine carbons with very high activities are used. However, with severely graphitic ore, the carbon associated with the rock may outperform the granular activated charcoal.Chemical Oxidation, in which the ore is subjected to preliminary chemical oxidation techniques to oxidize carbonaceous materials using such diverse reagents including ozone, sodium hypochlorite, calcium hypochlorite, chlorine gas, permanganates, perchlorates, chlorates and oxygen prior to subjecting the oxidized ore to standard cyanidation treatment to extract gold. This is generally a costly method and will not prove economical on a low-grade ore."

Jan 1, 1992

By K. Meyer

"The largest cost centres of the David Bell Mine concentrator are grinding, leaching and effluent treatment. Optimizing results during the 6th year of operation are listed below: o SAG mill slurry density control and operating strategies improved liner life and media consumption by 10 and 25%, respectively.o Poly-met liners clad the SAG mill except for the feed end. Lower noise levels and reduced mill downtime have resulted in an improved and more efficient workplace (time required for liner changes is 2 to 3%).o A comparative grinding media study using seven different marked media at the same time showed media wear rates range 120 to 198 mg/kWh and ball mill charge replacement frequencies of 8.3 to 13.1 per year, and that a meaningful wear test must include all media to be tested at the same time in the same mill. High quality carbon steel cylinders had the best economics.o Pre-aeration, using pure gaseous oxygen is accomplished in pipe reactors. Small bubble generators provide oxygen in the first three leach tanks. 1500 to 3000 kg of oxygen is consumed per day. Leach kinetics have improved and trends indicate increases in gold recovery of three to seven ounces per day at reduced costs. Effects of reduced cyanidation of accessory metals on the effluent treatment plant will be discussed in a separate paper."

Jan 1, 1991

By The Staff

THE object of the work was to increase the capacity of the plant and, if possible, to reduce costs of the actual unit grinding while doing so. The accompanying assays of an infra-sizer analysis of the cyanide tail (Table l) illustrate the problem in hand. The cyanide tail is a combination of two products, gangue and FeS2. The assay alters by virtue of a change in gold value due to grinding and the relative quantity of FeS2 in the sizes, which itself varies with the grind. The disposal tail is the residue after the cyanide tail is scavenged by flotation, most of the pyrite being removed for roasting. It presents a somewhat different problem, since grinding gangue is all gain, but -10 micron FeS2 does not float nearly as well as + 10 product. This results in compromise in the final size to be aimed at. Extra grinding has hardly any appreciable effect on the gold extraction from the FeS2. (See Milling Investigations Into the Ore as Occurring at the Lake Shore Mine; Trans. C.l.M.M., Vol. XXXIX, 1936).

Jan 1, 1940