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This paper discusses three case studies conducted at Highland Valley Copper mine (HVC) that illustrate operational improvements and insights which resulted from using the McGill University gas dispersion sensors. In the first study, the superficial gas velocity (Jg) sensor was used to implement a gas profiling control strategy for the rougher, scavenger and first cleaner cells in the Cu/Mo separation circuit. The data showed a 40% reduction of down-the-bank Cu recovery at constant Mo recovery which resulted from operating the cells at the target profiles. In the second study, the bubble size analyzer was used to better understand two mechanisms of bubble formation in the two flotation columns that make up the final Mo cleaning stage: the conventional rubber-sleeve sparger and the Microcel(TM) system. The data showed a considerable reduction of bubble size in the Microcel column which resulted in a significant increase in concentrate quality (1-2% Mo absolute) and a dramatic (4-5 fold) increase in concentrate production rate compared to the typical operation. The estimated economic benefit resulting from the improved column flotation operation was an overall 4% increase in Mo circuit recovery. In the third study, real-time measurements obtained from the gas holdup and bulk density sensors were used to infer the pulp density (% solids) in a rougher cell of the bulk flotation circuit. Validation tests demonstrated that this approach provides reliable pulp density measurements. Although promising, more work is required before implementing this approach at HVC.

Jan 1, 2009

By J. C. Loretto, H. A. Simons

The paper discusses how, in the routine testing of ores, insufficient communication between the laboratory and the design personnel can lead to misunderstanding or misinterpretation of test results and consequent design errors. A number of examples are given together with suggested modified interpretations and the resulting dollar savings indicated by these new interpretations.

Jan 1, 1972

By Jean-Guy L. Gauthier

"With the Ontario Ministry of the Environment stipulating that the cumulative concentration of copper, lead, zinc and nickel in mine mill effluent must be no greater than 1.0 milligram per litre, it has become necessary for the mining industry of find some form of treatment for the removal of heavy metals from effluent waters.To comply with these guidelines, it became necessary for Mattabi Mines Ltd., which is situated 50 miles Northeast of Ignace in Northwestern Ontario, to develop a compact, cost effective and technically sound treatment process to remove heavy metals from their tailings overflow. A design committee consisting of mine metallurgists, environmental engineers, a Dutch research and development team and the equipment supplier engineering staff was set up to accomplish this.Using some new and innovative wastewater treatment equipment, the guidelines established by the Ontario Ministry of the Environment can now be met. The sludge produced from the precipitated heavy metals is sent directly to the concentrator, thus eliminating the danger of re-dissolution of the metals in a landfill site, while recovering some of the valuable metals that would otherwise be wasted in a sludge landfill."

Jan 1, 1980

By B. Dyck, L. Verhelst

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

Jan 1, 2018

By D. Bernard

Over the last decades, the wrought aluminum casting industry has made significant progress with regards to process consistency by the introduction of new technologies in the field of liquid metal processing and casting. These technologies, combined with the application of best practices, have led to increases in productivity as well as better process performances and product quality. The competition in the addedvalue aluminum products (by opposition to P1020 production) is, however, very strong and involves players that did not hold a major role five years ago but who are now exerting a strong competitive pressure on our industry even sometimes from far abroad. There are still technical and technological challenges remaining in the different areas of aluminum casting production, amongst which metal pre-treatment, furnace operations, in-line treatment and casting hold a predominant influence. The comprehension of the contribution of each individual process step to the entire process chain is a key element and must be considered in future process optimisations. This paper presents the technological position of the casting industry and tries to highlight areas where further progress can be made.

Jan 1, 2006

By R. S. Adhikari

This paper presents an innovative computer vision method for condition assessments of bridges with multiple defects in bridge elements using digital images. This work utilizes 3D model of existing bridges and overlays digital images on 3D model to simulate on-site visual inspection. The analysis of element condition index (ECI) of bridges requires information about the severity and extent of defects in elements. In general, ECI is evaluated manually during routine bridge inspection considering the severity of dominant defects. The evaluation of ECI with multiple defects needs to be addressed with consideration of dominant defect as well as the interaction among defects. However, Image-based quantification techniques largely depend on geometry of objects (i.e. shapes). Shape vectors of a given object change as they are translated, rotated, and scaled with different magnitudes. This work considers shape preserving algorithms such as, affine and projective transformation for proper image alignment. Semi-automated approach for detection and quantification of concrete distress such as cracks and spalling are considered for the defects analysis. The proposed methodology ensures the consistency in reporting ECI and eliminates the shortcoming of traditional approaches.

Aug 1, 2013

By Eric D. Marks

Fatalities resulting from ground workers colliding with objects and construction equipment accounted for approximately 18% of the total construction fatalities experienced in 2010. Current injury and fatality measuring methods have proven to be inadequate due to their use of passive measures of safety rather than a more active approach, such as the use of leading indicator data (also called near misses) of hazardous proximity situations between ground workers and heavy equipment on construction sites. The objectives are to create and evaluate the effectiveness of a reliable algorithm for collecting and analyzing the resulting leading indicator data from hazardous proximity situations. Numerous experiments emulating typical interactions between workers-on-foot and heavy equipment are used to evaluate the proximity sensing and detection technology. Safety leading indicator data (also called near misses) generated by the proximity sensing and detection technology during the experimental trials are used to create and assess the resulting algorithm. Results from the experiments indicate that leading indicator data generated from these systems can be processed and analyzed to identify hazardous proximity situations and incidents on construction sites.

Aug 1, 2013

By D. F. VanDine, H. George

"The possibility of spoil pile failure at the Kara Kara bauxite strip mine, Guyana, South America, is of major concern to the mine operators. The current mining technique requires the continuous operation of an 11 ms bucket capacity walking dragline on top of 18 metres of freshly spoiled uncompacted overburden material consisting of varying mixtures of kaolinitic clay and quartzitic sand. A field biased geotechnical study of undisturbed overburden and corresponding spoiled material has identified site-specific, non-linear correlations between vane shear strength, standard penetration resistance and spoil pile composition. Readily available geological exploration borehole logs has enabled a composite clay isopach map of the entire mining property to be drawn and critical areas to be zoned according to expected slope stability. Stability has been assessed using simple hand calculation techniques. Use of the resulting stability map provides the mine operators with a means of forecasting the need for appropriate preventative measures at varying stages of mine development, throughout the life of the mine.A similar investigation procedure could be employed at many presently operating and future strip mines.IntroductionThe Kara Kara bauxite stripe mine is located at Linden within the bauxite belt of Guyana in South America. The mining property covers a total area of 88 hectares of flat to gently sloping ground of which some forty per cent is being actively mined or being preparatorily stripped of overburden, prior to eventual mining (George and Gordon, 1979). The regional climate is tropic and humid. Temperatures vary from 16°C to 38°C and yearly rainfall averages 2600 mm, with at least 55 per cent of this precipitation occurring during the 'wet season' months of May to July and December to January."

Jan 1, 1983

By David C. Mulder

As a result of the dramatic growth of Edmonton, Alberta during the past decade and the rapidly increasing price of natural gas, Edmonton Power has received provincial government approval to construct and operate an 8O0-megawatt- capacity coal-fired thermal generating station at Genesee, about 50 km southwest of Edmonton. The power plant will consist of two 400-megawatt steam-driven thermal generators, with provision in the future for two or more additional units. The coal will be hauled by truck from the nearby three-million-tonnes- per-year strip mine, with economically recoverable reserves exceeding two hundred million tonnes. Edmonton Power controls a major part of the coal leases in the area, and is working with other lease holders in developing the most efficient mining plan. A natural depression was selected as the site for the 600-hectare cooling pond to provide water for the power plant. Edmonton Power is working closely with the people in the area to ensure that their rights and concerns are communicated and recognized by all parties.

Jan 1, 1981

By M. P. Filion, K. Ferguson, L. L. Sirois

Acidic drainage is the largest single environmental problem facing the Canadian mining industry today. Technologies to prevent acidic drainage from occurring in wasterock piles and tailings sites, and on the walls of open pits and underground mines, need to be developed and demonstrated. There are two groups in Canada which have accepted this challenge: the national Mine Environment Neutral Drainage (MEND) program and the British Columbia Acid Mine Drainage (BCAMD) Task Force. This paper summarizes the activities of these two organizations.

Jan 1, 1990

By Jean-Luc Collins

"This new tool can be used as a quick guide f or the assessment of the potential economic wealth of any risky capital project. It does provide an unambiguous recommendation of the type ""go or no go"" to the decision-maker simply by comparing two different ratios profit/investment. One ratio determines the minimum value required to at least break even while the other measures a probable value based on the asymptotic theory of statistical extremes.Its application is briefly illustrated by means of an underground gold mine extension project, an oil sands mine project and a polymetallic open pit project.Once a favourable recommendation has been obtained then a detailed ""cash flow after taxes"" analysis can be carried out for the project.IntroductionMany tools are used in financial decision-making such as the payback period, the discounted cash flow, the internal rate of return and the wealth growth rate (Berry , 1971).These tools are useful and meaningful in evaluating normal projects closely related to regular business where the number of assumptions made is usually very small and where the cost of capita! is usually selected as a discount rate or a hurdle value. In situations where a significant number of assumptions have to be made,two problems can emerge, namely:I. the risk involved is underestimated leading to a potential financial disaster; or2. a good opportunity is lost because the approach used in evaluating the project is too conservative.Each assumption has its own degree of uncertainty and it is well known that combining uncertainties together can lead to a total uncertainty of critical proportion. The easiest way to account for risk is to increase the discount rate or the hurdle value, but this approach alone is quite subjective and can easily lead to the problems described above."

Jan 1, 1993

By L. E. Puddington, A. L. Mular

"Since the inception of spherical agglomeration, few investigations to exploit commercially the technique in the metallurgical field have been conducted. Of these, none appear to have been carried sufficiently far to demonstrate commercial feasibility.This paper describes a continuous agglomeration-separation process that can rapidly handle large tonnages of ore material. A small pilot plant de-signed from information obtained with the semi-batch unit described herein is currently in operation.In the absence of a reagent recovery system or cheap reagents, the process is probably not economically attractive for many common ores. However, for iron ores, the fuel content of the agglomerates can be used in a subsequent step such as direct reduction."

Jan 1, 1968

By L. S. Beck

"IntroductionThe Beaverlodge District is an important mineralogenic province of pitchblende and occupies about 1300 square kilometres centred on Beaverlodge Lake near the north shore of Lake Athabasca in northwest Saskatchewan (Fig. 1). Uranium City is the main settlement of the area and is serviced by scheduled aircraft from Edmonton, some 700 km to the southwest, and from Prince Albert which lies a similar distance to the south.During the summer, boats and barges supply the area from the railhead to Fort McMurray via the Athabasca River and Lake Athabasca, a distance of about 550 km. For the past few years a winter road has been maintained across Lake Athabasca to Cluff Lake to connect with Highway 155.The topography of the area is typical of the Precambrian Shield with generally low relief and a disorganized drainage of numerous lakes separated by hummocky rock ridges, muskeg and drift-covered areas. Local topography in the area is, however, extremely rugged, particularly south and east of Beaverlodge Lake, where resistant rocks form prominent hills and ridges extending as much as 180 m above lake level. Rock exposures are abundant and form over 50 per cent of the land area.History of Exploration and DevelopmentEconomic interest was first aroused by Tyrrell (1896) who described an occurrence of iron formation at Fish Hook Bay; however, subsequent evaluation of the deposit indicated it to be uneconomic."

Jan 1, 1986

By Keith Jones, Largo Albert

"Decelerometer testing of a rigid guide system in a mine shaft pro vides usefuI information to operating and maintenance people. High acceleration/deceleration rates can lead to high maintenance costs to bath conveyances and shaft and can also present an operating risk . Possible disastrous results in the shaft have been avoided by restricting the maximum conveyance speed until the shaft and/ or conveyance problems have been solved.The test instrument is a valuable aid especially during commissioning or updating of a hoisting installation. High acceleration/deceleration rates also lead to reduced hoist rope life. During the past fourteen years, a total of 15,000,000 feet of testing was performed in 74 assorted shaft compartments.Based on this experience, it is possible to establish acceptable conveyance maximum speeds provided that all other conditions in the shaft compartment are normal. The body of the paper will present examples of several tests made under actual operating conditions.IntroductionMore and more mine operators are recognizing the real value in the use of the decelerometer for determining the state of shaft guide alignment in their shaft compartments , not only during the initial mine start-up periods, but also on a regular basis while the mine is in production.Decelerometer testing, is a technique in which an accelerometer , commonly known as a decelerometer, is used for measuring conveyance acceleration/deceleration in a lateral plane. lts purpose is to determine the severity of shock loads produced by misaligned shaft guides. Testing is performed by mounting the instrument on the conveyance and operating the conveyance (empty and loaded) at various speeds up to and including full speed . However, full speed may not be attained due to conditions indicated by the tests. These conditions may present an operating risk to the plant."

Jan 1, 1984

By R. J. Grant, D. W. Scott, M. A. Cooper, E. R. Shannon

"The Brunswick No.12 site concentrator processes 10,500 tonnes per day of a complex lead, zinc, copper and silver ore producing four concentrates by differential flotation. Research over the years has led to increased understanding about the mineralogical and flotation characteristics of the ore. A pilot plant study conducted at Lakefield Research, primarily designed to investigate the technical feasibility of semi-autogenous grinding, provided an opportunity to test recent theories about grind size,, reagent schedule and flowsheet configuration.A fundamental approach was taken with each of the unit processes involved in grinding and flotation. Basic operating and metallurgical criteria were established in each area and a step-by-step implementation program initiated in the plant.Significant improvements in metallurgical and financial performance have been realized through the application of basic grinding and flotation principles using conventional milling equipment and without major capital expenditure. Current operating practice is detailed and metallurgical advancements cited.INTRODUCTIONBrunswick Mining and Smelting operates one of the world's largest lead and zinc mines near Bathurst, New Brunswick. Brunswick is a publicly traded company with majority ownership held by Noranda Minerals (63%). In addition to the No. 12 underground mine, the company operates a lead smelter and phosphate fertilizer plant in Belledune, N.B. and maintains a 25% interest in a joint venture with Noranda Minerals' Heath Steele mine near Newcastle, N.B. Through the four operations, a total of 2000 people are directly employed with fixed assets totalling Cdn$187 million (BM&S, 1991)."

Jan 1, 1993

By M. Gangal, M. Grenier, D. Mchaina, S. Hardcastle

"Exposure to airborne respirable silica in surface and underground mine operations is known to be the cause of industrial lung diseases. For this reason, silica is a regulated substance and worker exposure must be monitored regularly. Diesel exhaust also contains substances which are potential caricinogens. In an underground setting, diesel particulate may be the main component of what is referred to as respirable combustible dust (ReD). Although diesel particulate or soot is not at present a rigorously regulated substance, new epidemiological data is prompting North American institutes and agencies to regulate diesel soot or RCD exposure. This paper describes a method where by silicaand RCD exposure may be determined using a single personal sample. In this method, an airborne respirable dust sample is obtained and analyzed nondestructively for silica components using an on-filter X-ray diffraction method. Filters are then ashed at 500°C in a muffle furnace over a four-hour period to determine mass loss due to RCD burning. Using on-filter X-ray diffraction analysis as opposed to redeposition of dust samples onto another analytical substrate allows the"

Jan 1, 1992

By Jie Zhu

Coal bumps are a special form of release of geologic strain energy that has already been one of the most dangerous hazards to underground mining safety in China. A number of coal-bump models have been developed to quantify coal failure under assumption that a bump is a kind of non-gas induced outburst. However, some technical experts in charge of micro-seismic and gas monitoring have found unusual gas emissions before and after bump, which suggests that it is possible for gas to trigger coal bumps. Considering the coal reservoir as geological body composed of the coal matrix and gas, a new model based on Lippmann?s bump model is proposed to understand the initiation of coal bumps. The redistribution zone from excavation of a roadway has been calculated and analyzed regarding its relation with mining depth. It is shown that high gas pressure may push the coal seam to overstep the critical state due to extension of the plastic disturbed zone, and this is harmful to the stability of coal seam. This model successfully explains the bump phenomena of the Xinzhouyao mine at shallow depth.

Aug 1, 2013

By R. Hammen, J. Lifton

"The purification of rare earth elements (REE) at mining operations is traditionally accomplished by multiple chemical phase-transfer processes including precipitation, solvent extraction, and ion exchange. We describe REE purification results with Solid Phase Extraction (SPE) columns that were developed to improve the speed and economy of REE purification. The SPE columns have the properties of enhanced equilibration kinetics, so that residence time of a few seconds will accomplish selective chemical transfers from solution phase to solid phase. We describe the separation of REE’s as a class from leach solutions and the further purification of REE salts. INTRODUCTIONHistorically the rare earths were first chemically separated from each other and purified by fractional crystallization. This slow, cumbersome, and laborious process was not suited to commercial production. Solvent Exchange (SX) technology was applied to the problem of separating and purifying the rare earth elements when it was determined in the late 1960s that there might be commercial uses for them individually. At the same time the very slow and expensive technique of ion exchange was applied either for ultra-purification of the desired “light” rare earths, or for the recovery and purification of the tiny amounts of higher atomic numbered, “heavy,” rare earths. Solvent Exchange (SX) has today become the standard for separating the rare earths across their atomic number spectrum. Whereas the separation of the light rare earths commercially may take 30 “cascades’ in a modern Chinese plant, the total separation of all of them from each other may take up to 80 such “cascades,” and is only even “practical’ with preconcentrated feed stocks, such as those produced in China by heap-leaching techniques performed in situ on very low grade radio-nuclide free ionic absorption clays.. Ultra-pure materials of all types are produced today by ion-exchange processing of ionic species already separated by solvent exchange.Hard rock deposits and refractory residues of tin mining and residues from uranium mining have been identified outside of China with very high ratios of dysprosium and other heavy rare earths to the majority lighter ones. Several issues face those who wish to process these materials so as to separate the heavy rare earths commercially:"

Jan 1, 2012

By M. H. Allan

SASKATCHEWAN POWER CORPORATION is a Provincial Crown Corporation responsible for the production transmission and distribution of electric power and natural gas in the Province of Saskatchewan. Through the electric power responsibility, we became interested in the coal reserves in Saskatchewan, which, although still somewhat of an "orphan fuel" in the early and mid 1950's, gave the promise of providing a low-cost source of energy for electric generation. Coal in Saskatchewan, a lignite with an "as-received" heating value of from 5000 to 6500 Btu's per lb and up to 40% moisture, was first recorded in 1853 . By the end of the 19th century, many small mines were in operation in the Estevan, Coronach and Shaunavon areas supplying local inhabitants with a cheap source of heat. These small mines, some of them prosperous, some of them not, continued operation right up to the late 1940's, when oil replaced coal in the market place. The year 1930, however, saw the introduction of the new technique of strip mining in the Estevan area. This technique revolutionized coal mining. It was now possible to use large machinery to uncover the coal and cast the overburden to one side instead of burrowing through thin seams of coal varying from 2 to 10 feet thick. The overburden cast aside by these large mechanical shovels, or later draglines, created heaps of spoil which at that time, during the depression, were a sure sign of prosperity and the welcome news that people had jobs. By the late 1940's, coal production had dropped off, but the spoil piles remained and were now labelled by some as "scars on the landscape", even though there had been some natural succession of grasses. In addition, some people had planted trees in experimental plots and even some aerial seeding had been done.

Jan 1, 1978

By S. Akhlaghi

In many electronic/optoelectronic devices, interaction between the metal stack and solder is undesirable. If a reaction happens, a nonuniform joint containing spikes and voids is likely to form and as a result the heat dissipation deteriorates significantly, which in turn, leads to the degradation of the bond. In the present work the interaction between Ti/Mo/ Au metallization system, which was sputter deposited on AlN substrates, and Pb-Sn solder was studied by using scanning electron microscopy (SEM). Also, an EDX system was used to trace the changes in chemical composition of the layers after solder tests. The microstructural examinations show that the Ti and Mo layer from the Ti/Mo/ Au metallization system are not impermeable enough and thus Ca from the surface of the substrate moves all the way up to the interface of Au/Mo and forms an intermetallic at the interface, which grows over time.

Jan 1, 2006