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By A. Shakoor, T. P. Gautam

The long-term slaking behavior of clay-bearing rocks in the field can be quite different than the short-term slaking behavior in the laboratory. To assess this difference, 12 replicate samples of each of 20 clay-bearing rocks, including 5 claystones, 5 mudstones, 5 siltstones, and 5 shales, were exposed to natural climatic conditions for 12 months. After each month of exposure, one replicate sample of each rock was removed from natural exposure and its grain size distribution was determined. Disintegration ratio (DR), defined as the ratio of the area under the grain size distribution curve of the slaked material for a given rock to the total area encompassing all grain size distribution curves of the tested samples, was used to quantify the amount of disintegration under natural climatic conditions. DR values of naturally exposed samples were then compared with the corresponding values of second-cycle slake durability index (Id2) determined in the laboratory. The relationship between Id2 and DR after, 1 month of exposure, exhibits an R2 value of 0.65 but the relationship deteriorates when DR values for 6 and 12 months of exposure are used, with R2 values of 0.63 and 0.25, respectively. However, when DR values for laboratory samples, computed from grain size distributions of slaked material after second cycle, are compared with DR values of naturally exposed samples for the three periods of exposure, the relationship improves with the corresponding R2 values being 0.61, 0.71, and 0.41. These results suggest that DR may be a better parameter for assessing the long-term disintegration behavior of clay-bearing rocks than Id2.

Jan 1, 2015

By T. Vovan, A. Galibois, M. Fiset

"In order to establish some links between the 22 specimens found on the site of Les Forges du St. Maurice, their slag inclusions have been analyzed by electron microprobe. Comparison between their contents of various specific oxides allowed us to segregate them into two major groups and even to isolate two sub-groups possibly characterized by some equilibrium between their oxides and/or the type of ores used.In all probability, limes/one coupled systematically with a soil rich in hydrated aluminum silicates was used as a flux.Based upon the existence of a pseudo equilibrium between the slag and the metal, the elaboration of the bulk of the specimens can be ascribed to the indirect rather than the direct method whereas the process temperature can be estimated at at least /400°C.RESUMEDans le but d'etablir des liens entre les 22 objects provenant des Forges du St-Maurice, leurs inclusions de scories ont été analysées par microsonde. La comparison des teneurs en divers oxydes a permis de les séparer en deux groupes majeurs et même d'y distinguer deux sous-groupes pouvant être reliés à la forme d'équilibre entre certains oxydes et/ou au type de minerai utilisé. Selon toute vraisemblance, le fondant utilisé était de la pierre à chaux à laquelle on ajoutait systématiquement une terre riche en silicates hydratés d 'aluminium.Des considérations sur l'existence d'un certain équilibre entre les scories ei le métallaisset croire que la plupart des objets ont été élaborés plutôt par la méthode indirecte que directe et que la température d'élaboration se situait à au maint 1400°C."

Jan 1, 1984

By Z. Xie

Gas diffusion electrodes (GDEs) for high temperature polymer electrolyte fuel cells (PEFCs) have been prepared using ZrP-modified Nafion ionomer. The performances of these GDEs as cathodes and anodes were evaluated and compared with conventional Nafion ionomer GDEs using Nafion 112 as the PEM under elevated temperature and reduced relative humidity. ZrP-modified Nafion ionomer was incorporated into the catalyst layer to enhance water retention and/or increase the protonic conductivity. The fabrication of ZrP-GDEs was implemented by the ion exchange of Nafion solution with zirconyl chloride, followed by the impregnation of GDEs in H3PO4 solution. The composite electrolytes in the catalyst layer possessed a ZrP content of 20% by weight. GDEs were characterized by TGA, SEM, XRD, and CV. Scanning electron microscopy (SEM) indicated evenly distributed elemental Zr and P within the catalyst layer. Cyclic voltammetry shows a reduced electrochemically-active surface area when the ZrP is incorporated into GDEs. Polarization and impedance analyses indicate the cathode with ZrP-modified Nafion ionomer did not show an enhanced or decreased performance, compared with conventional Nafion ionomer GDEs under elevated temperature and decreased humidity. However, when GDEs with ZrP¬Nafion ionomer were used as the anode, an improved performance was observed. Preliminary experiments show that the anode is more sensitive to dehydration than the cathode under elevated temperature and/or low humidity. Improving the anode water retention capability will help to reduce losses at the anode. However, the incorporation of hygroscopic agents in the cathode catalyst layer is not essential because it is self-humidified by electrochemically-produced water even under elevated operating temperature and lower humidity.

Jan 1, 2005

By Robert B. Parsons

"The new Ontario Liberal government introduced its first budget in October. The changes to The Mining Tax Act proposed in the budget are mean t 10 simplify the current system without any loss of revenue to the government. It goes without saying that some operators will benefit from the changes while others will pay more taxes after 1985.With regard to ongoing matters at the federal level, the proposed carve-out legislation and the issue of northern allowances are being discussed with government officials, and a small victory has recently been scored with regard 10 the laxation of certain share transactions of prospectors and grubstakers. A report on these issues is provided herein.Ontario BudgetOn October 24, 1985, Ontario Finance Minister Robert F. Nixon tabled a budget proposing several significant changes to both the Ontario Mining Tax Act and the province’s income tax legislation.Mining Tax ActA flat rate of tax and reduced processing allowances highlight proposed changes to The Mining Tax Act. The proposed changes, with a comparison to the existing system, are set out in Table I.The most significant change is the replacement of the graduated tax rate schedule with a flat 20010 tax rate. This is a welcome change for most mine operators who viewed the high rate of 30% on profit over $20 million as counter-productive.However, the flat rate of ta x may not be welcome to all operators. Generally speaking, operators with less than $ 10 million annual profit are better off under the graduated rate system, while operators with annual profit exceeding $10 million will benefit from the 20010 tax rate."

Jan 1, 1986

By R. H. Keyes Duval

"The one point left off the table was pumping costs, i.e. the cost of pumping to the cyclones.At East Malartic 5 x 5 S R L pumps that had been used to pump the classifier overflow were used to pump the rod and ball mill discharges to the cyclones. Maintenance costs on the pumps rose from $105 in 6 months to $1000 per month. The pumps had to be operated at 1150 rpm and impellers lasted only 5 to 6 days. These pumps were replaced by 6 x 6 S R. L. pumps operating at 825 rpm, but at this speed the coarser sands settled and plugged the pipe lines and the speed was increased to 925 rpm. The maintenance cost is now $100 per m::rnth which is 0 003 cents per ton milled. The impellers now last 1 month and the casing linings 6 months.Density meters are often used on cyclone overflows and sometimes on the cyclone feed. Haliburton weighted tube density meters are used in some plants. They are cheaper than the radioactive density controller, $2500 as compared to $ 6000The angle of the discharge spray from the apex can be used to judge the quality of perform1nce of a cyclone.For ordinary metallurgical applications the inside slope of the cyclone is not too important but for fine separation steeper slopes are used.The cyclone is a versatile tool and will handle considerable variations in feed tonnage - probably up to 15%. Above this variation the number of cyclones used has to be increased or decreased or the tonnage fed to them has to be adjusted"

Jan 1, 1965

By T. A. Postolski, A. J. Sinclair

"Abstract - Where block (selective mining unit) grade distributions can be determined, the effect of average random errors of block grade estimates on metal recovery can be evaluated quantitatively. That is, for a given estimation error and cutoff grade, it is possible to calculate the quantity of metal that is lost as a result of misclassifying ore blocks as waste, as well as the dilution that ensues from misclassifying waste blocks as ore. Example calculations using a computer program GAINLOSS and realistic block grade distribution parameters for both a porphyry-type deposit and an epithermal gold deposit illustrate some fundamental relations that are important in quality control of estimation and in reconciliations concerning a comparison of ore estimates with production.Where the cutoff grade is on the lower tail of the grade distribution, metal arising from dilution can be much less than metal lost through misclassifying ore as waste. Hence, average grade of milled material could possibly be higher than expected (estimated) and tonnes milled will be smaller than estimated.Where the cutoff grade is on the higher tail of the grade distribution, tonnes arising from dilution will be greater than tonnes lost by misclassifying ore as waste. Thus, tonnage mined will be greater than estimated and the average grade milled will be less than estimated.The software GAINLOSS permits rapid comparison of the tonnes and average grade for all blocks selected as ore for a variety of levels of block estimation errors. These comparisons can be incorporated in a financial analysis to evaluate whether or not it is worthwhile to improve a high, average block estimation error to some lower value."

Jan 1, 1998

By L. McFarlane, D. Rollwagen

"Madawaska Mines produces a uranium precipitate (83-85% u3o8) using a magnesium oxide slurry to precipitate the uranium from solution. The solution, at approximately 9""0 g/l u3o8 is neutralized to a pH of 7.0. At the Eldorado Nuclear Refinery in Port Hope, the precipitate is not acceptable as a single feed to the refinery process. It was discovered that a 2% silica impurity caused emulsion problems in the solvent extraction column.After extensive studies of possible solutions, such as two-stage precipitation and solvent extraction, an acceptable solution was found. The selective precipitation of uranium at a pH of 3.5-4.0 using Hydrogen Peroxide produces an almost silica free product of higher purity (90-93% u3o8) to that of straight magnesium oxide precipitation. Introduction Madawaska Mines Limited is located four miles southwest of Bancroft, Ontario. The annual production of u3o8 is approximately 610,000 pounds. To produce the final product or yellowcake, nine separate steps are required. These are (1) grinding, (2) dewatering, (3) leaching, (4) acid filtration, (5) clarification, (6) ion exchange, (7) precipitation, (8) washing, and (9) drying and packaging. To illustrate these steps, a complete flowsheet of the mill is displayed on page three.The yellowcake is sent to Eldorado Nuclear Limited in Port Hope, Ontario for further concentrating and refining. As part of their routine specification check, a test called the amenability test is performed. This test indicates how a particular dissolved yellowcake product reacts to solvent extraction. The Madawaska yellowcake did not pass the test."

Jan 1, 1982

"In today’s world of complex projects, where engineering and execution are supported by a high level of project management and systems, how critical is the human factor in design engineering. Based on his involvement on a variety of projects, Tony Lipiec will relate his experiences as the impact of 4 factors: the ‘team’ involved in the design and execution of the project; the project and information systems supporting the project; the impact of scope, time, and budget; and finally the selection of the proper success criteria to judge the project and the people who have enacted the project.The discussion of the team will relate to the quality of people and the impact of their knowledge, attitude and experience. It will also look at the relationships and interests of the various stakeholders. Decision making and taking responsibility will be discussed.Supporting the team are the management, document and information systems. The value that these systems bring to the project as a whole will be examined. How project size impacts the applicability of the systems will be discussed.Scope, time and budget are recognized as critical. Reference will be made to the interplay between these components which are vital to project success. The issue of iterative design and whether it is necessary will be considered together with the development of supporting technical information.Finally the selection of the proper success criteria and the awards provided to the team can have a big impact on the final, production success of the project. The author will discuss his views on the impacts of these on EPCM projects."

Jan 1, 2016

By B. A. Sparkes, J. H. Reeves

"The St. Lawrence Granite hosts vein-type fluorite mineralization that was mined until 1977. Recent drilling identified a significant fluorite-bearing structure hosted in adjacent meta-sedimentary country rocks. Several phases of vein fill and brecciation indicate there are three phases of fluorite mineralization, of which the later two phases are volumetrically significant. The earliest fluorite is purple and occurs along joint and fracture surfaces, in fault-breccia matrices, and as stockwork veins. The second phase comprises primarily red, yellow, blue-green, and white colours of fluorite. The latest phase is green with lesser clear fluorite. Identification of fluorite veins in the meta-sedimentary rocks opens up new areas for exploration.RÉSUMÉ Le granite St. Lawrence contient une minéralisation filonienne de fluorite, laquelle a été exploitée jusqu’en 1977. De récents forages ont permis d’identifier une structure importante contenant de la fluorite encaissée dans des roches métasédimentaires adjacentes. Les nombreuses phases de remplissage de filons et de formation de brèches indiquent qu’il y a eu trois phases de minéralisation de fluorite et les deux dernières sont importantes d’un point de vue volumétrique. La plus ancienne fluorite est mauve et se trouve le long de surfaces de joints et de fractures, dans les matrices de brèches de failles et en tant que stockwerks filoniens. La deuxième phase comprend surtout des fluorites de couleurs rouge, jaune, bleu-vert et blanc. La fluorite de la plus récente phase est verte avec des quantités moindres de fluorite claire. L’identification des filons de fluorite dans les roches métasédimentaires ouvre de nouveaux secteurs pour l’exploration."

Jan 1, 2016

By William H. Pomroy, Kenneth E. Hjelmstad

An underground mine fire can seriously threaten the lives of all personnel in the mine. This fact makes fire emergency planning a high priority in the mining industry. A fire emergency plan includes a means of warning miners of the existence of a fire, and the need to evacuate or retreat to a place of refuge. The warning alarm must be fast and must reach all miners, regardless of their location or work activity. Means of fire warning are varied, and include such methods as stench, flashing lights, telephones, and word-of-mouth (messengers). Unfortunately, none of these methods are entirely satisfactory. Stench can be slow and seldom achieves total mine coverage, especially in high-back room-and-pillar mines with low ventilation velocity. Telephones are effective only where personnel are close enough to hear the phone ring. A novel fire warning alarm system has been developed by the U.S. Bureau of Mines which enables instantaneous warning of all underground personnel. The warning alarm is sent by an electromagnetic signal which penetrates through mine rock from a transmitter to small person-wearable receivers. Each miner's cap lamp battery could be equipped with a small receiver and when a fire or other emergency occurs the miner could be alerted to the danger by a blinking of the cap lamp. Testing of prototype equipment has demonstrated that the transmitted signal is capable of penetrating through over a mile of mine rock and activating the receiver. This paper describes the theoretical basis for through-the-rock ultra-low frequency electromagnetic transmission, design of the prototype transmitter and receiver, test results, and status of commercial development of systems utilizing this technology.

Jan 1, 1994

By Leon J. Perrier

The paper describes the equipment in use, haulage grades, road conditions, tire sizes, tire performance and related problems. Various types of failures and causes, corrective action taken, tire records and reporting for control are also discussed.

Jan 1, 1977

To date, improved thickening of clay mineral dispersions presents major technological and environmental challenge to mining and mineral processing industry worldwide. Flocculant-assisted dewatering processes currently employed during thickening are far from being efficient, requiring further development and process optimisation for dramatic improvement. In this paper, recent studies carried out to modify (i) pulp chemistry, (ii) flocculation performance and (iii) particle interactions to significantly improve the dewatering behaviour of flocculated, model and plant smectite and kaolinite clay dispersions are presented. It is shown that pulp pH-mediated hydrolyzable metal ion hydrolysis and specific adsorption in tandem with high molecular weight flocculant and shear may synergistically act to significantly enhance the dewaterability of both clay mineral pulps. Furthermore, polymeric flocculant structure type is demonstrated to show clear links with floc shear sensitivity, and hence, flocculation performance and pulp dewaterability. The implications and relevance of the findings plant clay mineral waste tailings thickening operations are drawn.

Jan 1, 2006

By W. L. Ennis

Introduction This paper outlines the causes of underground fires at Noranda Mines and the precautionary measures taken to guard against such fi res. Shafts There are six shafts (Figures and lA) on the property, of which N os. 1 and 2 are abandoned. Nos. 3, 4, and 5 are the present working openings from surface and No 6 is an internal shaft. No. 3 is used primarily as a service shaft, while Nos.?1 and 5 are the main hoisting shafts. Orebodies The orebodies are of two distinct types. There are the massive sulphide bodies, and the areas of mineralized rhyolite containing gold values and a silica content high enough for fluxing purposes. The massive sulphide bodies contain chalcopyl'ite, pyrite, pyrrhotite, and minor amounts of sphalerite and magnetite. The concentration of particular sulphides varies even within the same body. It is the areas high in pyrite, and to a lesser degree those, high in pyrrhotite, that are of particular interest.

Jan 1, 1950

The dissolution of chalcopyrite has received a significant amount of attention. The predominant paradigm of investigation is that its rate of dissolution is limited or passivated by a surface coating or film of material. The common candidates for such a passivating coating are numerous: polysulfide coating, metal deficient layers, copper sulfide coating, bornite layers, jarosite precipitates, and elemental sulfur films. While this line of explanation, that is, the explanation based on passivation, seems to have won some form of consensus with researchers, there is another explanation for the results that can account for all the results observed. Crundwell (1988) proposed that the solid state properties of chalcopyrite, in particular, the semiconducting properties, are responsible for the observed behaviour of chalcopyrite. The purpose of this paper is to outline the semiconductor mechanism of dissolution, and to show how this mechanism accounts for all the observed phenomena recently reported in the literature. The paper outlines the semiconductor mechanism of dissolution, shows how this mechanism accounts for the dissolution

Jan 1, 2014

By C. Samuelsson, G. Carlsson

Characterization of dust from Boliden Mineral AB’s copper-plant in Sweden was carried out using chemical analysis, X-ray diffraction analysis, energy dispersive analysis and wave length analysis using electron microprobe equipment. Dust from four different locations was characterized: the electrostatic precipitator (ESP) after the roasting furnace; the ESP after the copper smelting furnace; from the copper converter ventilation bag house filter; and from the bag house filter collecting dust from the settling furnace and tap gas ventilation. The results showed that the dust is composed of small solid and/or liquid particles from the furnace reactor which have been transported with the process gas to the dust collecting devices. This portion of the dust is mechanically formed. It also contains compounds that have been vaporized in the process and then condensed from the process gas at lower temperature, chemically formed dust. The proportion of mechanical and chemical dust varies with the process generating the dust.

Jan 1, 2001

By B. J. Walsh

ABSTRACT Segregation of sphalerite minerals in zinc concentrates into christophite, marmatite and ordinary sphalerite by means of magnetic fractionation is investigated. A Frantz ferromagnetic filter, 1.2 amp., and a Dings magnet, 0.3 amp., is used to fractionate seven zinc concentrates produced in the Province of Quebec. The Dings magnetic product contains the pyrrhotite, and the sphalerite as christophite. The Frantz magnetic product contains sphalerite as marmatite, while the Frantz nonmagnetic product contains ordinary sphalerite. The results indicate that the magnetic susceptibility of sphalerite increases with increasing isomorphous iron content and that a satisfactory separation into christophite, marmaite, and ordinary sphalerite may be accomplished by magnetic fractionation. INTRODUCTION SPHALERITE, the chief ore of zinc, is almost never pure zinc sulphide. Iron is almost always present isomorphously replacing an ?equivalent amount of zinc. What may be referred to as 'ordinary' sphalerite contains up to 10 per cent iron. More highly ferriferous varieties, with 10 to 26 per cent or more iron, have been named marmatite .and christophite.

Jan 1, 1951

By T. Gerritsen, C. Martinez, F. Stober, T Ma, J. R. Frias, M. Sedighy, J. Janzen

Electrode control systems regulate power by physically positioning electrodes. Due to the weight and inertia of the electrodes and hoist equipment, this is a relatively slow process where power fluctuations of less than a few seconds are not fully corrected. Nickel laterite AC furnaces operating in high voltage, shielded arc mode typically incur frequent power variations of approximately +/- 20% or more around the power set point. To provide enhanced power control, Hatch has recently supplied, at commercial scale, a thyristor-switched reactance system called an SPLC. The SPLC incorporates predictive control software to operate furnaces at the maximum transformer rating by reducing the large power swings experienced without the SPLC. The resulting higher average power enables higher production, without increasing transformer or power plant capacity. A 60 MW production version of the SPLC has been commissioned on Falconbridge Dominicana's laterite nickel furnace, yielding excellent results with a 3 to 1 reduction in power fluctuations.

Jan 1, 2005

By G. J. Govett

THE RESERVES of industrial minerals of the Western Plains are probably several times more valunable than all the known deposits of metallic minerals of the Canadian Shield, though sharing little of the latter's popular appeal. Because of comparatively low value per unit weight or volume, an adequate and accessible supply of industrial minerals is essential for the full development of any territory; assessment of the value of deposits should consider fully the proximity to cheap transportation, and existing and potential markets. Production statistics of industrial minerals are probably a more reliable guide to economic development than, for example, those of petroleum, and the relative importance of industrial minerals increases with growth of the population. The development of a high-volume natural deposit such as petroleum naturally favours an increase in population, and thus industrial minerals form an integral part of an expanding industrial economy. This situation is clearly demonstrated by the relationsl1ips of industrial minerals production, petroleum production, and population growth, in Alberta (Figure 1).

Jan 1, 1959

By E. C. W. Perryman

BEFORE describing the methods used for fabricating uranium into various shapes and sizes it is necessary to illustrate briefly the unusual conditions under which uranium has to operate when used as a fuel element in a reactor. During reactor operation, for every fission that occurs two atoms of intensely radioactive fission products are produced together with two or three neutrons. The neutrons that are ejected possess several m.e.v. of energy and when one of them strikes an atomic nucleus, that atom acquires up to 105 e.v. of kinetic energy. This is large enough to displace the atom from its lattice position and send it shooting through the crystal, displacing other atoms out of their lattice positions. The net result is that a large number of vacancies and interstitial atoms are formed within the crystal lattice which sometimes have profound effects on the physical and mechanical properties of the material in question.

Jan 1, 1957

By Wm. D. Jr. Sheldon

THIS paper presents practical data to aid in the selection of a mine ventilating fan, and outlines considerations to be made to ensure satisfactory operation and optimum efficiency of the fan. Much has been published on the general subject of mine ventilation, but the writer has found few specific data on factors and considerations which govern the selection of a fan-data which should be available to the operator if his fan is to give satisfactory service within the range of the high-efficiency portion of its performance curve and deliver the specified air capacity when operating against the anticipated range of resistance of the mine. The total quantity of fresh air furnished by the ventilation system must be adequate to provide, and to ensure at all times, safe and healthful working conditions in the mine. It is assumed that the mine operator is able to determine the air quantities required for the various parts of the mine.

Jan 1, 1941