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By Vlad Ruzicka

"Uranium deposits in the Rabbit Lake-Collins Bay area are associated with the sub-Athabasca unconformity which separates crystalline Archean or Aphebian basement rocks from Helikian clastic sedimentary rocks of the Athabasca Group. The basement rocks are a part of Wollaston lithostructural domain.Most of the high grade deposits, such as Collins Bay ‘A’ and 'B' Zones and Eagle Point are associated with altered rocks of the basal unit of the Wollaston Group. Some deposits, such as Raven and Horseshoe are confined to the uppermost unit of this Group. The Rabbit Lake deposit occurs in the middle, meta-arkose unit of the sequence. Locations of some deposits (Rabbit Lake, Collins Bay ‘A’ and 'B' Zones) are also controlled by thrust faults, such as Rabbit Lake Fault and Collins Bay Fault.The deposits contain either monometallic (uranium) mineralization (Rabbit Lake, Raven, Horseshoe) or polymetallic (mainly uranium-nickel) assemblages (Collins Bay “A’ and 'B' Zones).IntroductionThe Athabasca Basin region, a part of the Churchill Geological Province of the Canadian Shield, is composed of Archean and Aphebian crystalline basement and younger, Helikian, unmetamorphosed supracrustal rocks. The Rabbit Lake-Collins Bay area is situated at the eastern margin of the Athabasca Basin region, which hosts a substantial proportion of Canadian uranium resources.The crystalline basement complex was subdivided by Lewry and Sibbald (1979) into lithostructural domains and these domains were grouped into major crustal units designated, from northwest to southeast, as Western Craton, Cree Lake Mobile Zone, consisting of Wollaston, Mudjatic and Virgin River domains, and Rottenstone Complex (Fig. 1)."

Jan 1, 1986

By J. C. Kurnia

Presence of fine dust in air causes serious health hazard for mine operators resulting in such serious problems as coal workers? pneumoconiosis and silicosis. Major sources of dust appear of course along the mining face where the minerals are extracted. Proper control and management are required to ensure safe working environment in the mine. Presented here is the use of a computational fluid dynamic (CFD) approach to investigate the flow and dust behaviour in mining tunnels. The objective of this study is to propose and examine various strategies to mitigate dust dispersion from the mining face and reduce dust concentration to a safe level for the operator. In a companion study, the authors investigated various methods for mitigating dust dispersion from the mining face to ensure safe dust concentration levels in the mine tunnel. Among the examined methods, implementation of brattice to direct the flow from the main airway to the mining face is the most effective method to disperse dust particles away from the mining face. The installation of brattice, however, will limit the movement of mine operators and vehicles in the tunnel. Hence, application of a hybrid brattice which is a combination of a physical brattice along with suitable directed and located air curtains is proposed and examined. Based on the CFD simulation results, over a range of parameters of interest, it was found that the physical brattice blocks the ventilation air and directs it to the mine face while an air curtain located along the brattice outlet offers flexibility in keeping the dust away from the operator allowing more freedom for the operator and the equipment. Results of the modelling over a range of parameters of interest are presented and discussed with the goal of managing dust concentrations within safe limits for the operator.

Aug 1, 2013

By L. Sun

A numerical model has been developed to study the air flow in the flow plate and gas diffusion layer assembly on the cathode side of a PEM fuel cell. The flow plate in this type of fuel cell often has serpentine channels and the porous layer is adjacent to the flow plate to diffuse the air to the catalyst layer. Flow cross-over of air through the porous diffusion layer from one part of the channel to another can occur. This flow cross¬over is a result of the pressure differences between different parts of the channel, and it causes the flow rate through the channel to vary with the distance along the channel. A numerical study of pressure distribution and flow cross-over through the gas diffusion layer (GDL) in PEMFC flow field using a serpentine channel system has therefore been undertaken to compare the cases of a single channel and two parallel channels, with the channels having a trapezoidal cross-sectional shape. The purpose of the present work was to study the effect of the flow plate geometry on the basic fluid flow through the plate. The flow here has been assumed to be three-dimensional, steady, incompressible, isothermal and single-phase. The flow through the porous diffusion layer has been described using the Darcy model. The dimensionless governing equations have been solved by using the commercial CFD solver, FIDAP. From the results obtained, it can be found that the single channel systems have greater maximum flow rate difference than the parallel channel systems under the conditions considered in the present study. Also, the size ratio R of trapezoidal cross-sectional shape has a significant effect on the flow cross-over and pressure variation in the flow field.

Jan 1, 2005

By E. Busse, J. E. Burgener, J. G. Eacott, M. C. Robinson, P. E. Burgener

"This paper presents a preliminary assessment of the technical and economic feasibility of a caustic leach - electrowinning process for the recovery of zinc and lead from electric arc furnace baghouse dust at a mini-steelplant. Recent studies and literature are referenced briefly as they pertain to the formation and characterization of dust, toxicity considerations and alternative dust treatment and disposal options.Laboratory testwork results, published data, pilot plant experience and anticipated influences resulting from recycling residues are used for the purpose of developing a conceptual design for a caustic leach - electrowinning plant to treat 15,000 tonnes/year of dust at a one million tonnes /year capacity steelplant in Canada.Target economic studies, comprising preliminary estimates of capital and operating costs, revenues and rate of return are presented. Economic and commercial considerations concerning the relative merits of dust treatment at a centralized facility compared with an on-site plant are discussed.IntroductionThe treatment or disposal of mini-steelplant electric arc furnace (EAF) baghouse dust has been given increasing attention in recent years for two principal reasons. Firstly, the dust is now classed as a hazardous waste material under V.S. EPA regulations which prohibit its disposal in dumps other than controlled landfill sites. Secondly, the dust contains certain metal values, notably zinc and lead, which may be economically recoverable, depending on the costs associated with disposal resulting from enforcement of the EPA regulations. Other metallurgical dusts and waste materials, from both ferrous and non-ferrous operations, may require the same considerations as EAF baghouse dust.Several studies have been carried out to examine various aspects of dust treatment but few commercial plants are in operation. Technology employed uses pyrometallurgical techniques. Commercial-scale hydrometallurgical plants are not known to exist although small-scale plants are frequently more economically attractive than their pyrometallurgical counterparts which generally require economies of scale to be viable.The concentration of mini-steelplants in northeast V.S.A. and southeast Canada merits study to determine whether or not dust treatment for metals recovery is a commercially feasible alternative to disposal.This paper examines the technical and economic feasibility of a caustic leach - electrowinning process for the recovery of zinc and lead from EAF baghouse dust at an on-site ministeel plant processing carbon steel scrap and discusses economic and commercial considerations pertaining to dust treatment at a larger, centralized facility."

Jan 1, 1984

By G. M. Ritcey, M. Silver

"The processing of uranium ores produces tailings that could constitute environmental problems. At most operations the tailings are dumped into a designated area, with the ultimate acid drainage occurring if sulphides are present, together with the release of metal constituents to the rivers and streams. If the chemical reactions occurring within the tailings could be predicted, perhaps methods could be developed to either increase or decrease 'the rates of reaction. One such study has been in progress at CANMET during the past three years. The paper describes the use of Iysimeters containing low-grade and complex uranium tailings to determine the effects and interactions of bacteria, sulphides and solvent extraction organics on the release of radionuclides and on acid production. A simulated rain cycle nine-fold the normal was used and the Iysimeters were subjected to timed intervals of light and darkness. As a result, the tests simulated a 25-year period.IntroductionAlthough Canadians derive major benefits from uranium, there are environmental and health consequences, not yet fully understood, from the associated mining and milling operations. A major project at CANMET (Canada Centre for Mineral and Energ y Technology) has the ultimate goal of ensuring that any adverse effects on man and environment, now or in the future, resulting from the processing of uranium should be acceptably low. The magnitude of the task was exacerbated by the fact that the increased demand for electrical energy and the resultant increased prices for uranium oxide during the 1970s led to a rapid expansion in the industry. Annual world demand for uranium was expected to increase 12-15 fold in the next quarter century, with annual requirements of between 200,000 and 300,000 metric tonnes anticipated by the year 2000. Currently, the demand is low and the prices for the oxide have decreased."

Jan 1, 1982

By K. J. Brouwer, J. P. Haile

"Construction of the first stage of the tailings disposal facility for the Montana Tunnels Project was completed in October 1986. The project is located 37 km south of Helena, Montana, and involves mining of42 million tons of weathered diatreme are at a rate or 13 500 tpd to produce a gold/silver dore, as well as lead and zinc concentrates. The tailings disposal facility for the project includes a fully drained tailings impoundment for storage of the tailings solids, and a process waterpond for storage of all decanted water prior to recyling to the mill. The over-all facility is designed to achieve the basic objectives ofminimizing seepage to the environment in the short- and longterm, and achieving a fully drained stable tailings mass suitable for immediate reclamation on completion of mining. Specific features of the design include a soil bentonite seal and drainage system within the tailings basin, a free draining embankment with a design flow-through capacity of 4000 US gpm and an ultimate height of 230 ft (70 m), and a soil bentonite lined make-up water pond with a capacity of 420 acre-feet (530 000 m'). The tailings will be discharged in a rotational sequence through multiple spigot offtakes to achieve a thin-layer low energy laminar flow. This 'sub-aerial' deposition results in higher stored densities and maximizes liquid-solid separation on the tailings beaches. The over-all design played a major role in the successful permitting of the project, and was significantly cheaper than a conventional wet disposal system, with overall unit costs for tailings disposal of less than US$0.36 per ton.This paper outlines the site characteristics and the tailings material properties and their influence on the design. Extensive use was made of naturally occurring free draining materials as well as bentonite modified soil liners within the tailings basin, embankment and retention ponds. General construction procedures for the various components are described, as well as on-going construction requirements utilizing materials from the open pit. Finally, the over-all costs and unit costs for tailings disposal are presented."

Jan 1, 1988

By D. A. Trotter

"Low-pressure sodium light sources have been available for several years, but have not received wide acceptance in underground mining. This is because they are difficult to operate using DC power, they are not an intrinsically safe light where explosive gases may be encountered and they give poor colour rendition.With the need for energy conservation, several Canadian hard-rock metal mines are now changing their lighting to low pressure sodium, as it has the highest efficacy of any light source in terms of lumens per watt. Studies have pointed out several other advantages as well. Glare can be controlled, they penetrate fog well, they are easily maintained, they have a long life and they give the highest visual acuity when compared to other types of lighting. As well, in an underground mine, contrast is much more important than colour for task identification. For close work, the colour problem is alleviated with the use of cap lamps.Case studies are presented from Canadian practice. These show how the lights are modified for underground use, calculations preceding light installation, and how and where the lights are installed in the underground environment. Mention is made of worker reaction to the lights and possible physiological effects.IntroductionThe importance of good underground lighting to the total environment of mining cannot be overemphasized. In addition to the obvious benefits of improved worker morale, available studies show that good lighting practices reduce accident severity and frequency as well as increase production."

Jan 1, 1982

By W. D. Fogwill, P. J. Clarke

"The Dawn Lake uranium deposits are located 340 km north of La Ronge, Saskatchewan, in the Athabasca Basin between the Midwest Lake and Rabbit Lake deposits. Four zones of uranium mineralization, called the ""11, 14, 11A and 11B Zones,"" lie within the Athabasca Sandstone, at the sub-Athabasca unconformity and in the basement.At Dawn Lake, approximately 100 metres of Helikian Athabasca Group clastic sediments overlie Aphebian Wollaston Group pelitic and calcareous metasediments and pegmatites. Uranium with some nickel, cobalt and copper, occurs near the sheared stratigraphic contact between calc-silicate gneiss and graphitic, pyritic pelite. The mineralization lies in an area of low magnetic susceptibility which is thought to represent a rock sequence lying stratigraphically high within the Wollaston Group. There is no obvious vertical displacement of the unconformity by faulting, despite considerable brecciation, shearing and slickensides seen in the basement rocks. This suggests horizontal displacement on steeply dipping wrench faults as the main tectonic control along the 11, 11A and 11B trend.Below the Athabasca unconformity, the Wollaston Group rocks are altered to fine-grained mixtures of clays, chlorite and silica commonly called regolith. Along the mineralized trend post-Athabasca fracturing and (or) compaction have occurred through this clay-rich alteration zone, causing the steeply-dipping primary foliation to become contorted. This ""crenulated"" horizon can reach depths of 35 metres below the unconformity and is thickest along fault zones in the calc-silicate rocks. The ""crenulite"" is a distinctive unit which at Dawn Lake is commonly found above pods of ore located deep below the unconformity.Much of the mineralization in the 11A and 11B Zones occurs above, beside and below the thickest part of the crenulated zone, although the crenulated rock itself contains negligible amounts of carbonate, pyrite and uranium. Intense vuggy alteration and collapse breccias are found in calc-silicate rocks deeper and to the west of the 11A and 11B mineralization. There are at least two ages of uranium deposition in the basement zones, shown by small bright cubes of ""pitchblende /"" overgrown and replaced by duller botryoidal ""pitchblende II. ""Sooty pitchblende and yellow secondary minerals are the result of still younger reworking.The geological setting of mineralization, along the contact between carbonate-rich calc-silicate rock and pyritic pelite, suggests that the uranium was concentrated at a pH/Eh boundary located between deeply weathered, carbonate-rich and sulphide-rich basement rocks."

Jan 1, 1986

By D. Letzig

Wrought magnesium alloys are of special interest as lightweight structural components as a result of their more homogeneous microstructures and improved mechanical properties compared to cast components. Extrusion as a shaping technology offers the possibility to produce a wide variety of magnesium alloy profiles. In this contribution we describe the role of extrusion parameters such as extrusion speed, ratio and temperature as well as the type of extrusion process on the microstructural development of AZ-series magnesium alloys and the resulting mechanical properties. The effect of microstructure on the tensile/compression deformation behavior of the alloys has also been investigated. Aspects of process optimization designed to overcome technical and economic limitations and thus establish magnesium alloy profiles for industrial applications will also be discussed.

Jan 1, 2006

By J. L. Dion

"A study of the techniques to integrally cast copper tubes in copper tuyeres for use in blast furnaces has been carried out. The work has been performed in support of current efforts to produce two-compartment tuyeres having improved water-cooling capacity. A test pattern corresponding to a vertical section of a two-compartment tuyere, and including a cast-in-place copper tube, was used to investigate such variables as tube preparation, tube coolant, pouring temperature, pouring rate and gating design. Successful castings, either with a good metalfurgical bond or good intimate contact between the tube and the casting, were produced, with all combinations of gating system and position of the tube tried. However, the pouring temperature, the pouring rate and the effectiveness of the coolant are interrelated and must be controlled to produce a good metallurgical bond.IntroductionAs part of its contribution to, and in collaboration with, the Copper Casting for the Steel Industry Committee, CANMET has undertaken research into the methods and techniques needed for the integral casting of copper tubes into high-conductivity copper castings.The objective was to produce two-compartment copper blast furnace tuyeres in which the water-cooled nose compartment consists of a copper tube metallurgically bonded to the wall of the high-conductivity copper casting. This design, developed in the UK, has demonstrated a much extended service life with attendant economies; unscheduled shutdown of blast furnaces due to tuyere failure is a significant problem in the steel industry. The Canadian steel industry believes that this design will replace the currently used single-compartment tuyere in blast furnaces within a few years.The technology to produce these tuyeres does not exist in Canada. One of the main features is the inclusion of a smooth-walled cooling channel in the nose, which permits high velocity cooling water to be employed. A second compartment acts as a reservoir backup, should failure in the nose occur. This would allow continued use of the tuyere for a period of time, permitting a scheduled shutdown for repair s. To assist the Canadian producers of tuyeres to maintain their market, and the Canadian steel industry to have a reliable domestic supply, it is important that the necessary technology for the production of two-compartment tuyeres be developed and transferred to industry."

Jan 1, 1982

By L. I. Kiss, S. Perron, D. Toulouse, S. Poncsák, A. Perron

Bubbles play an important role in many industrial processes. In a Hall-Heroult cell, used for aluminum production, bubbles contribute to induce flow in the cell. The induced flow is important for the thermal balance of the cell as well as for the distribution and dissolution of the alumina. The existence of the bubble layer does not have advantages only. It increases the voltage of the cell and causes deformation along the cryolite-molten aluminum interface. The role of the anode inclination in the behaviour of the bubble layer as well as in the hydrodynamics of the bath is not clearly understood. In this work, the effect of the anode inclination angle on the bubble driven flow is studied in an industrial scale air-water model. The inclination angle is varied up to 5° from the horizontal. The instantaneous flow field is captured by Particle Image Velocimetry (PIV) system. The mean velocity fields were calculated by ensembleaveraging the instantaneous velocity fields measured at different time. The existence of the counter-flow in the interpolar space and the vortex in the side channel has been confirmed. Furthermore it has been observed that the effect of anode slope on the velocity field is weak.

Jan 1, 2006

By A. Montini, M. H. Moys

"A conductivity probe mounted in the shell of the mill has been used to measure the behaviour of the load in the mill as a function of operating variables. It was found that certain properties of the conductivity signal correlate strongly with the per cent solids of the slurry passing through the mill; in particular the angular location ?D of the shoulder of the load is an increasing function of the per cent solids. A method for measuring the viscosity of the pulp discharging from the mill has also been developed. The use of the measurements in mill control is illustrated by simulating various control strategies for open circuit milling. It is shown that the use of ?D allows very tight but imprecise control of the slurry rheology in the mill, while the use of viscosity is subject to severe limitations in speed of response. A cascade control system involving both measurements provides adequate control of slurry rheology within the mill. Applications to closed circuit milling are discussed.IntroductionMultivariable control of milling circuits continues to receive a lot of attention in the literature. Hulbert and co-workers and Niemi, et al. have described the use of Inverse Nyquist Array (INA) techniques while Herbst has recently described the use of Optimal Control. It is significant that in neither of these three projects was any variable associated with the grinding mill itself (e.g. power or properties of the mill discharge) used in the control strategy. Pauw, et al.do, however, use mill power in their multivariable peak-seeking controller for pebble-mill control. Little work has been published on the use of measurements of the properties of the slurry being discharged from grinding mills, in spite of the fact that milling efficiency is known to be strongly affected by slurry rheology».Moys has recently developed a technique for measuring the dynamic behaviour of the load in the grinding mill. This method involves the monitoring of the response of a conductivity probe mounted in the shell of the mill which gives a measurement of the orientation of the load inside the mill. It was found that the load behaviour was strongly influenced by slurry rheology. In this project a technique was also developed for the measurement of the viscosity of the slurry in the mill discharge. It was, thus, decided that it would be worth investigating the use of these measurements in mill control schemes since direct control of the slurry rheology in the mill must inevitably increase the efficiency and productivity of the grinding circuit as a whole.This will be done by using the dynamic responses measured by Moys and Montini to simulate the behaviour of an open circuit ball mill. While the control of open circuit mills is of little interest, this simulation provides a simple but powerful demonstration of the advantage provided by these measurements, advantages which should apply to closed circuit operation of any mill type (including autogenous milling). Investigations into multivariable control of a closed circuit ball mill are currently nearing completion and will be published soon."

Jan 1, 1987

By L. A. Melis, A. R. Marchbank, S. A. Webster

"Certain northern Saskatchewan uranium ores have a high content of nickel and cobalt which offer the potential for recovery as a by-product to uranium. A nickel/cobalt recovery process has been developed as a viable method of recovering a marketable concentrate from typical uranium raffinate solution.Impurities are first removed from the raffinate and the pure solution is then treated with sodium carbonate to recover a bulk nickel/cobalt carbonate precipitate for sale to a primary nickel producer. All contaminants of concern are removed to very low levels and the product is free of radioactive contamination with gamma emissions significantly below natural background. Cost estimates have shown that installation of a nickel/cobalt recovery circuit within a uranium process plant is economically feasible.The testwork that led up to the selected process is described along with recommendations for further investigations such as additional testing of hydroxide precipitation as a possible viable alternative to carbonate. The selected process is described and project economics are briefly reviewed.PROCESS TEST PROGRAMBackgroundExtensive metallurgical research has been performed over the years to develop a process for recovering uranium from the Midwest deposit in northern Saskatchewan. During the course of this research, a certain amount of information became available which suggested that recovery of nickel and cobalt from uranium raffinate could be economically feasible. It was decided to undertake a test program which would investigate methods of separating nickel and cobalt from radioactive and other metal contamination to permit production of a saleable product.Available technology suggested that three general approaches could be taken to recover nickel and cobalt. The first and simplest approach would be to selectively precipitate the impurities of concern, primarily arsenic, iron and radium, and then recover a bulk concentrate from the purified raffinate. The second approach would be to purify the raffinate and then remove cobalt from solution by solvent extraction producing pure nickel and cobalt solutions for further treatment. The third approach would be to precipitate all metals from solution and then selectively re-dissolve nickel and cobalt in ammoniac solution which would be further treated by solvent extraction for nickel recovery, leaving cobalt for further treatment."

Jan 1, 1993

By John H. Schloen

"The object of this paper is to review electrolytic copper refining as it was in 1954(1), as it is now in 1984, and to comment on the many improvements which have been made in the last thirty years.In 1954, and even in 1984, the ASTM specification B 115 for cathode copper was 99.90% minimum copper plus silver content and 100% minimum electrical conductivity, IACS standard. However, to meet competition and to satisfy the requirements of the fabricators and the electrical industry, the electrolytic refinery must supply a product of 99.95% to 99.96% minimum copper content, and 101fJlo minimum electrical conductivity.The range of cathode impurities reported by 20 major copper refineries in 1954 are given in Table I.The much more rigid British Specification, DD 78, for high-purity cathode copper, specifies individual elements, as well as groups of elements, as shown in Table 2.The Svenska test has been replaced by a similar procedure which uses 2.r mm diameter wire. The ISO test is the one listed in the DD 78 specification. In Table 3, corresponding values for the Svenska and ISO test s are given for various wire bar coppers."

Jan 1, 1986

By C. J. Mwenifumbo

Preservation of groundwater quality is a major environmental concern. The disposal of hazardous material from urban waste dumps, milling wastes in tailings ponds, and industrial wastes in injection wells may contaminate potential sources of potable groundwater. The containment or migration of contaminants in the subsurface depends on bedrock characteristics and type of overlying sediments. Fractured bedrock and permeable sediments that may provide pathways for the transport of potentially harmful contaminants should be avoided when selecting a disposal site. The role of borehole geophysics in hazardous waste-site investigations is reviewed in three categories: (I) site selection; (2) determination of the extent of contamination at existing sites; and (3) long-term monitoring of migration of contaminants. In the first category, borehole geophysical techniques developed for lithology and fracture identification, and for porosity determination, provide some of the necessary information for understanding the subsurface hydrogeology. Lithological information can be obtained from gamma-ray, electrical resistivity, induction, magnetic susceptibility, and sometimes induced polarization logs; fracture detection and characterization can be accomplished with the use of caliper, density, resistivity, temperature, and acoustic televiewer logs. Estimates of porosity are derived primarily from neutron-neutron, resistivity, density, and soniclogs. Borehole geophysical techniques used in water quality determinations include self-potential, fluid resistivity, Eh (redox potentials) and pH measurements, and these can be used to map the extent of contamination at an existing waste site. Cross borehole and borehole-to-surface electrical methods can also be used in this application. Long-term monitoring of contaminant migration in boreholes can be accomplished with techniques that respond to changes in electrical conductivity, temperature and fluid chemistry caused by the presence of contaminants.

Jan 1, 1993

By M. P. Kat, R. J. Barclay

"In 1984, a provincial inquiry into ground control and emergency preparedness in Ontario mines was commissioned by the Minister of Labour for Ontario. One of the recommendations put forth by the committee conducting this inquiry was that the Ontario mining regulations be modified to address more effectively the assessment of mine design. Mining regulations now require that every mine in the province annually assess its design with respect to ground stability. Subsequently, the Ministry of Labour has embarked on a ground control audit program to gather as much information as possible about the ground control programs in place at Ontario mines. In 1988, 47 underground mines were audited. The audits are intended to provide an overview of the level of engineering effort that is devoted to ground control on a provincial basis, by identifying the type of geotechnical information that is collected by each mine and how this information is used for stability analysis purposes in rationalizing excavation and support system designs. Also, the audits serve as an indicator of the severity of ground stability problems at individual mines, and how these problems are dealt with.This paper consists of information that has been extracted from the first series of ground control audits that were conducted in 1988. Specifically, the paper describes the types of support systems that are used in Ontario mines. It also discusses the rationale for local ground support selection, and the quality control programs that are in place for assessing the performance of installed ground support. As well, the type of geotechnical information that is collected, and to what extent it is used for the purpose of designing ground support systems, is reviewed"

Jan 1, 1991

By G. T. Lapidus, R. M. Luna-Sánchez

In the present study, a series of cyanidation experiments were performed on a bulk sulfide concentrate which contained silver in four distinct phases, to determine its extraction rate, varying the oxygen concentration. The results showed that three of the four phases were refractory, aguilarite (Ag,iSeS) being the only leachable phase, and that the effect of the oxidant concentration is minimal. Mathematical simulations were performed, adjusting only the Damkohler number to adequately fit the experimental data. This model, and the mechanism implied, was compared with that found for acanthite (Ag2S) in a previous study, and the differences between the two discussed.

Jan 1, 2005

By Gerald H. Luttrell, Lance Christodoulou, Jaisen N. Kohmuench, Michael J. Mankosa

The efficiency of the froth flotation process has long been known to be strongly dependent on particle size. For sulfide minerals, good recoveries are typically achieved in industrial flotation circuits for particles in the 30 to 200 µm size range. Particles outside this critical size are typically lost in industrial operations and rejected to tailings streams due to inherent constraints associated with the physical interactions that occur in the pulp and froth phases of conventional flotation equipment. In response to these limitations, a series of experimental studies were conducted to determine whether particles previously lost as tailings could be economically recovered using a suite of novel flotation technologies developed for upgrading ultra-coarse and ultra-fine particles in the industrial minerals industry. For the case of ultracoarse particles, a fluidized-bed flotation system called the HydroFloatTM separator was tested. The data obtained using this novel flotation device in both laboratory- and pilot-scale trials showed that good recovery of previously lost sulfide values up to 850 µm diameter could be achieved. Similarly, for ultrafine particles, a high-intensity cavitation-based column cell was tested. This technology, which utilizes highshear contacting of slurry and gas, was capable of recovering valuable ultra-fine sulfide that were previously lost due to the low capture efficiency of conventional flotation processes. The objectives of this article are (i) to describe the unique operating principles of these two advanced flotation technologies and associated ancillary classification equipment, (ii) to present laboratory- and pilot-scale experimental test data showing the metallurgical benefits of the proposed novel flowsheet for sulfide tailings processing, and (iii) to provide a generic cost-benefit analysis of the proposed system for recovering lost values in existing sulfide tailing streams.

Jan 1, 2016

By F. Mallozzi

"With the requirements of air pollution codes becoming more and more critical, the role of the ventilation engineer in industry has become an extremely important one. The ventilation engineer must provide the expertise for the selection of equipment and the design of systems which will reduce pollution to an acceptable level. Because pollution control systems involve considerable capital and operating expense, he must have the ability to select, from a wide range of products, the collector which will provide the required performance with a minimum of down time for maintenance. This paper discusses the principles of wet collection and the forces used to separate particulate matter from a gas stream. Important factors in the selection of equipment, such as collection efficiency, horsepower requirements and water consumption for the various types of collectors, are discussed in detail, as well as the construction features normally incorporated to circumvent potential problems."

Jan 1, 1971

By John E. Udd

"Mining research at CANMET is delivered by the Mining Research Laboratories Division (MRL), with facilities in Sydney, Nova Scotia; Bells Comers, Elliot Lake, and Sudbury, Ontario; and Val d'Or, Quebec. This paper gives an overview of the work of the Division as of early 1993. An addendum, at the end of this paper, describes the organizational changes that will take place in April 1994. IntroductionCANMET, the acronym for the Canada Centre for Mineral and Energy Technology, is the name by which the organization founded in 1907 as the federal Mines Branch is presently known. The name was changed in 1974, in order to give recognition to the importance of both minerals and energy technologies in the activities of the Branch. Further reorganizations have taken place since 1987. As a result of these, CANMET has assumed the status of a Sector (equivalent to the Geological Survey of Canada) and has been organized into four branches.The organization as a whole functions in an environment of semi-matrix management. Some of the ""line"" Divisions report to Directors-General for the appropriate branches while other, larger divisions, report directly to the Assistant Deputy Minister.The second dimension of the organizational matrix is composed of a number of ""staff' divisions which report to the DirectorGeneral for Policy and Planning. Each of these Divisions performs a function which is common to all of the ""line"" divisions. For example, the Research Projects Office is responsible for monitoring the range of research activities of CANMET and for recommending allocations of funds for both research contracts and operating budgets. The Library and Documentation Services Division is responsible for CANMET publications and information services. Likewise, the Engineering and Technical Services Division provides support through, among other services, the construction of specialized laboratory equipment."

Jan 1, 1994