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By M. Y. Solar, W. G. Davenport

Most of the recent growth in nickel demand has been for the production of stainless steels and virtually all of it has been satisfied by new ferronickel and nickel pig iron projects. But "good" laterite resources are more and more difficult to find: Ni grades are decreasing while Fe contents are increasing and SiO2/MgO ratios vary from 1 to 3 and even higher if limonites are included. Predicting the smelting behaviour of such ores requires a more fundamental understanding of the thermodynamics of these systems in commercial operations. One valid question is thus whether these furnaces are at thermodynamic equilibrium or not. The present paper investigates this question, compares calculated and measured O2 partial pressures and mechanical/chemical slag loss ratios and concludes that ferronickel furnaces are not at thermodynamic equilibrium. This departure from expectation is actually to the operators’ advantage: the targeted ferronickel grades can be obtained at lower reduction potentials than calculated from pure thermodynamics.

Jan 1, 2014

By Daniel Hodouin, Claude Bazin, René del Villar

"A traditional linkage has long been established at Laval University's Department of Mining & Metallurgy between the Mineral Process (MP) and the Mining Exploitation (Min) on one hand, and between the Extractive Metallurgy (EM) and the Materials Engineering (Mat) on the other. This academic separation of Mineral Processing from Extractive Metallurgy at the educational level has become increasingly at odds with today's industrial practice in which both disciplines are not only complementary but also often intertwined. For instance, in gold ore processing, comminution, flotation, and gravity separation units are interfaced with atmospheric or pressure leaching modules and with carbon adsorption and electrowinning units. The new copper plants in South America combine comminution and flotation circuits with heap leaching, solvent extraction and electrowinning processes.In order to reflect this new industrial reality and to harmonise the options offered in both its engineering programs, the Department of Mining and Metallurgy of Laval University has introduced major changes in its curriculum in 1996. These changes reflect also the recognition that the somewhat secondary status given so far to Mineral Processing and to Extractive Metallurgy within their ""mother"" programs, Mining/Mineral Engineering and Materials metallurgical Engineering respectively, was in sharp contrast with their actual significance for the Canadian economy. Leading industrial voices have raised similar concerns and the Canadian Engineering Accreditation Board has also addressed this problem in its latest program evaluation.The changes implemented at Laval aimed at a) better representing MP and EM within the two undergraduate programs; b) training top-level versatile and multidisciplinary engineers, fluent in all aspects of MP and EM, irrespectively of which of the two ((mother)) programs they had chosen and capable of meeting today's industrial requirements; c) training students in process analysis, optimisation and automatic control using state-of-the-art software, and d) taking into account the co-operative nature of both undergraduate programs.Results are very encouraging in terms of student enrolment and industrial response. However, some concern is expressed on the sustainability of the renewed curriculum considering the drastic budget restrictions in effect at Laval as in most other Canadian universities."

Jan 1, 1999

By C. Kennedy, S. Jensen

Traditionally, mineral processing plants are designed to achieve the highest recovery of valuable material with limited regard for the cost of managing waste products-both solid and water components. As an industry, we are confronting ever more stringent environmental standards and lower grade deposits requiring more intensive processing. The most profitable processing route can, in fact, lead to costly issues downstream. Issues or risks associated with waste management include water treatment and handling and storage of potentially acid generating material. The capital and operating costs of dealing with these issues are significant and should be considered as a consequence of plant design and optimisation. The authors of this paper are involved with a number of projects where process operation changes offer opportunities to mitigate risks associated with water and waste management. Examples of these changes will be discussed along with the estimated benefits to the value of the project and reduction of long-term environmental risks. Process changes include 1) the application of in-plant water treatment as opposed to dealing with the entire tailings management facility and 2) the potential to reduce metal leaching and acid rock drainage through the preferential liberation of carbonate minerals in the grinding process.

Jan 1, 2014

By F. P. Hassani, H. B. Poorooshasb

"A kinematically admissible velocity field is applied to study the arching phenomenon in a cohesionless granular backfill placed between two rough vertical inflexible walls. The study is different from the previous works which are almost entirely based on statically admissible stress fields. It is shown that the development of arches is strongly influenced by the previous loading history of the backfill which controls the nature of the constitutive laws that govern the mode of stress deformation of the backfill. This preliminary study employs simple models in order to show the potential use of such an approach in evaluating and understanding mine backfill behaviour in the underground excavation. The pressure exerted on the floor supporting the backfill is also studied in some detail.INTRODUCTIONAlthough the importance of the design of mine backfill has been discussed extensively by a number of authors, i.e. Hassani et al. (1985), such theories have not as yet been incorporated in design criteria for underground mine backfilling operation . One factor that such theories must incorporate is the so-called arching action .The phenomenon of arching has been the subject of study by many researchers in the field of civil engineering and mining engineering. Among these scholars the works of Terzaghi (1943), Krynine (1945), Lusher and Hoeg (1964) and Handy (1985) are noteworthy. All these authors use a statically admissible stress field as a starting point to develop their theories. The approach taken by the authors of the present paper is completely different because they employ a kinematicallyadmissible velocity field. It is their belief that the arching phenomenon is closely linked to the interlocking of grains as manifested by the degree of dilatation of the granular mass when subjected to a shearing process.This paper is written in the following sequence. To define the interlocking quantitatively it is necessary to state the constitutive law governing the stress deformation characateristics of the granular mass. This is done in the next section as the law proposed by Poorooshasb and Pietruszazck (1985, 1986) is stated and simplified to suit the present analysis. Next the mode of formation of an arch in a simple system consisting of a mass of backfill sandwiched between two vertical rough walls of infinite extent is examined. The velocity field obtained from the above example is used to obtain solutions to two more complicated situations. The first situation assumes that the backfill is supported, in addition to the vertical rough walls, by a Winkler foundation at its base. The second situation assumes that the Winkler foundation has been replaced by a horizontal beam of uniform section and simply supported at its extremities. The findings of the study are summarized and their practical implications discussed in the concluding remarks."

Jan 1, 1989

By Maarten van de Vijfeijken, Marco Rufli

"By using the latest generation of medium voltage frequency converters, new possibilities have arisen to improve the grinding process. Beside all the direct and indirect advantages, several dedicated functions have now been implemented for ring geared grinding mills in the minerals industry. The advanced operational functions ensure a smooth, safe and reliable operation with minimum stress for the mechanical equipment and therefore highest availability of the mill. Several papers have already been presented concerning the benefits of using this state of the art technology for mill drives (Ravani von Ow and Bomvisinho, 2010; Ravani von Ow and Gerhard, 2010). However this paper will not only show and explain the operational benefit of these functions, but will focus on the experiences gained with this kind of sophisticated ring geared mill drive system. Several measurements of different operating conditions (starting, frozen charge remover, controlled roll back, backlash, etc.) made on an installed and commissioned 2 x 5 MW dual pinion ring geared mill drive system will be shown and discussed. Also the accuracy of the load sharing between the two 5 MW motors during starting, normal operation and stopping will be demonstrated using real measurements from an operating system. Finally the inherent features of these drive systems are briefly discussed.INTRODUCTIONLooking at the demands of grinding mills, we can split them into operational, maintenance and protective demands. For smooth and safe operation, it is important that critical situations are avoided as much as possible. Maintenance functionality must be quick and easy to execute, while protection of the system is important during all operating conditions. ABB has considered all these demands during development of their dedicated mill functions. By adding an additional controller (mill controller), not only a lot of application related functionality and protection is included, but also the interface between the mill drive system and the customer’s distributed control system (DCS) is simplified."

Jan 1, 2011

By H. C. Counsell, R. Webber

"The mill at Denison Mines' Elliot Lake Operations started up in 1957, with a capacity of 6,000 tons per day. Over the years various plant modifications expanded th.is to 7 500 tons per day. In 1976, management decided to carry out a major expansion of the milling capacity, and during 1980 the grinding capacity was increased to 15,000 tons per day.The original comminution system consisted of a conventional crushing plant feeding minus S/s-inch material to rod and pebble mills, in closed circuit with mechanical classifiers. The key decision that had to be made was whether the expansion should include conventional or autogenous grinding flow sheets.During 1977, extensive pilot plant studies at Lakefield Research showed that two-stage semi-autogenous grinding, with some steel media in the primary mill and with pebble media in the second stage, produced stable grinding conditions. This type of circuit was selected by Denison for the expansion, and went into production in 1980. Primary millThe flow sheet of the semi-autogenous grinding circuit is shown in Figure 1. The primary grinding mill is a Koppers 28 foot by 10 foot mill, driven by a 4,000 h.p. synchronous motor. It is fed with a minus 8-inch run-of-mine ore, and 4-inch grinding balls are added as supplementary grinding media. There are two Koppers 15.5 foot by 22 foot secondary pebble mills, driven with 1500 h.p. synchronous motors. Each grinding stage operates in closed circuit with cyclones, and the primary cyclone overflow is the feed to the secondary mills. The circulating load in the primary stage can be controlled by adjusting the cyclone apexes."

Jan 1, 1984

By Christine Hansen

?Kiss my Asteroid? Unofficial Title Human life is tied to minerals It?s worth noting that: The living human body consumes minerals. The minerals we take in multivitamins show the close linkage between human beings and mineral resources. Unlike tourism or specialized manufacturing, a human being could not live without mineral consumption. Minerals and their consumption is a tangible part of human life.

May 1, 2013

By Y. Bai, J. J. Liu, D. Q. Li, S. Z. Liu, X. T. Wang

"This paper presents the results of an industrial test using 8 t/d of Baotou concentrate (50% REO) of a clean metallurgical process, which includes: 1. Roasting with H2SO4 at low temperature (220~260 0C) in a batch roasting furnace followed by water leaching to obtain a leach liquor as feed with a yield of >95% RE and Th, recovering F as fluoride, producing a leach residue amounting to 1/3 of an equivalent high temperature residue and containing <0.03% Th and radioactivity < 3×104 Bq/kg compared to the normal high temperature residue containing 0.2-0.3% Th and 1×105 Bq/kg. 2. Separating Th with N1923 and extracting RE by P507 has been completed in mixer-settlers. Test results indicate that the ThO2 product has a purity of > 95% with a yield of 99%, and the RE has a yield of >95%, in which ThO2/REO <5×10-6, and that P507 loaded RE connect straight with separating RE using P507-HCl system. 3. Treatment and multipurpose use of "three wastes" (water, gas and solids) are discussed in some detail."

Jan 1, 2014

By C. Jay Hodgson

Hydrothermal systems form on land where and when an impermeable cap-rock unit ( either natural or self-sealed) , a permeable aquifer. and permeable discharge and recharge channels (cross-stratal permeability) develop in an anomalously hot part of the crust. A consideration of the relationship between magmatic and tectonic events in volcanically active areas indicates these conditions arise during: (1) the resurgent doming stage of the resurgent caldera cycle; (2) following movement on the bounding faults of tilted fault blocks ; and (3) as a result of hydrothermal boring associated with the intrusion of major sills. On the assumption that the submarine hydrothermal systems which deposit volcanogenic massive sulphide ores are comparable to subaerial hydrothermal systems, it is suggested that: (1) the horizon of mineralization corresponds to the time period when conditions favour the development of hydrothermal systems, as outlined above; (2) exploration for Cu-rich Cu-Zn-Pb or Cu-Zn ores should be directed to paletopographically high areas near discharge conduits , whereas exploration for Cu-poor ZnPb ores should concentrate on paleotopographically low areas down slope from conduits; (3) deposits with stringer zones lying above normally permeable units may be underlain by regionally extensive weakly mineralized and altered zones (self-seal caps) ; (4.) in the absence of a self -sealed cap, the ore horizon may be underlain by a naturally impermeable unit (e .g. a fine clastic sediment) ; (5) the condition of cross-stratal permeability may be evidenced by features such as dykes. alignment of vari ous magmatic and hydrothermal phenomena, abrupt thickness changes in stratiform units indicative of ponding against syn-volcanic faults, and fault-scarp slump deposits; (6) the condition of high heat flow may be evidenced by near-surface magmatism and steep thermal gradients preserved in metamorphic mineral assemblages.

Jan 1, 1977

By Ray Walton, Ron Colquhoun, Ken Thomas, Dwayne Fentie, Barney Burke

"The new Roasting Facility at Barrick’s Goldstrike Mine in Nevada, U.S.A. was developed to process 12,000 tons per day of refractory gold ore. The process consists of crushing, dry grinding, roasting, extensive gas purification, calcine quenching and leaching in the presence of activated carbon. The new plant is integrated into the existing Goldstrike facility, treating ore from both open pit and underground sources.The process design, procurement, construction and commissioning of the Roaster facility was performed successfully over a 3% year period with peaks of 400 engineering personnel and 950 construction personnel supporting the project. The US$330,000,000 project was completed ahead of schedule and under budget. The commissioning was well planned and proceeded smoothly through a rapid start-up to achieve all primary goals within three months of the start of processing of ore.BACKGROUNDAs early as 1992, Barrick’s Goldstrike Mine, located north of Carlin, Nevada had indications of the ore becoming ever increasingly carbonaceous in nature. As the open pit and underground exploration programs proceeded to step out over the years that followed, the accumulative amount of carbonaceous refractory ore and tons had become significant. By 1997, 29 million tons of double refractory carbonaceous ore containing an estimated 11.6 million ounces of gold had been identified. By 2000 the resource had increased to 14.3 million ounces."

Jan 1, 2001

By A. J. MacRae

Metallurgical furnaces are made up of complex multi-component systems that must function either together or in parallel for safe, and reliable operation. Thermal expansion of single material components experience induced stresses during heating and cooling, which can lead to cracking or failure. Multi component elements and systems can experience significant thermally induced stresses during both steady state and transient temperature conditions. Examples pertaining to temperature effects on refractory, copper cooling blocks, furnace shells, and complete systems will be discussed. The purpose of the paper is to highlight how stresses and strains are developed due to differential thermal expansion.

Jan 1, 2015

By Yves-Laurent Turcotte

Notre conférencier, Monsieur Yves L. Turcotte, Vice-président et Directeur général chez Promaintech Novaxa est diplômé en génie industriel de l?Université du Québec à Trois-Rivières et détient une maîtrise en gestion de projets de l?Université du Québec à Montréal. Il est une véritable sommité canadienne dans le domaine de l?amélioration de la performance des organisations. Provenant d&apos;entreprises manufacturières et de services, il possède plus de 20 ans d?expérience en tant que développeur de technologies, conseiller et formateur auprès d?entreprises. Il a à son actif la réalisation de mandats dans plus de 400 entreprises. Il est reconnu pour sa grande capacité d?analyse et pour trouver des solutions novatrices et profitables aux problèmes des organisations les plus complexes. Aujourd&apos;hui, il dirige Promaintech Novaxa, une division de DMR, qui a célébré son dixième anniversaire en 2006. Cette organisation ayant des places d?affaires dans la région de Montréal, Québec et Vancouver compte plus de 50 professionnels et a une carte de visite dans 16 pays. Les axes d?intervention sont le Management, la Productivité, la Fiabilité, l?Innovation et l?Amélioration Continue.

Feb 1, 2008

By B. Dubé, R. Friedman, J. Oliver, R. Aubertin, M. Burson, G. Panneton, M. Hamilton, J. Ayer

"The Detour Lake gold deposit is located within the northwestern limit of the Archean Abitibi Subprovince of the Superior Province. Mineralized zones are hosted by a sequence of pillowed and massive flows, hyaloclastite units, and altered ultramafic rocks, and are commonly oriented parallel to a series of high-strain zones that are co-planar to the regional-scale Sunday Lake Deformation Zone. Early in its kinematic history, the Sunday Lake Deformation Zone placed older (2.72 Ga) volcanic rocks of the Detour Lake Formation over younger (2.70 Ga) sedimentary rocks of the Caopatina assemblage. Gold mineralization is also parallel to the position of a laterally persistent siliceous rock unit, the 2.725 Ga ‘Chert Marker Horizon.’ The Chert Marker Horizon coincides with the boundary between the mafic-dominated upper Detour Lake Formation and the ultramafic-dominated lower Detour Lake Formation. Stratigraphic and geochronological data suggest that the Chert Marker Horizon is a deformed felsic volcaniclastic unit. At a cut-off of 0.6 g/t Au, the Detour Lake deposit contains 17.26 million ounces of Au within 445.9 million tonnes of rock grading 1.20 g/t Au. Gold occurs in shear-hosted and extensional vein arrays within rocks of the upper and lower Detour Lake Formation and within the Chert Marker Horizon. The Detour Lake deposit has many of the characteristics of a greenstone-hosted, quartz-carbonate vein deposit; its very large size may be attributed to large-scale rheological controls resulting in the formation of dilatant sites in permissive rock units."

Jan 1, 2012

By J. Y. Hascoet, M. Marya, S. Marya

Additive manufacturing (AM) brings disruptive changes over the ways parts and products are designed, tested, qualified, assembled, inspected and marketed. With these changes come real technical challenges, therefore, concerns that mainly stem from the maturity and diversity of today’s AM processes, the feedstock materials, and the interactions between the numerous process parameters. Additive manufacturing is somewhat similar to laser and electron-beam conduction-mode welding and involves a multitude of dynamic physical events between projected feedstock and moving heat source that influence process robustness, thus deposit properties. For this paper, a simple air vent, selected for its size, thin-wall, hollow geometry and materials (specifically 316L) was made using a laser-based powder blown technology (Construction Laser Additive Direct or CLAD) and systematically inspected by optical microscopy, microhardness indentations, and electron-back-scattering diffraction (EBSD). This exemplary part is first analyzed to broadly discuss metallurgical phenomena in additive manufacturing, particularly solidification and texture development. The paper then expands to other alloys and continues correlating metallurgical observations to process parameters and part properties, also borrowing from past experience with the same 3D printing CLAD system.

Jan 1, 2014

By Marius Jacobs

"Safety performance in many companies and even industries has stalled in the few years. Accidents rates are at a "plateau" and yet, serious accidents and fatality rates are not. In more dramatic cases, such as in the BP Texas disaster, organizations that have "exemplary" safety statistics, suddenly have a catastrophic or multi-fatality event occurring. Other classic examples are the Piper Alpha disaster and NASA’s Challenger and Columbia disasters and even the Chernobyl nuclear reactor. Looking into the root causes of these accidents provides an insight into the events and deficiencies that led up to the accident, but what are the common features in the organization’s mindset? What characterizes these organizations’ decision-making, their approach to safety and to risk and are there specific cultural features that can be delineated? The research and review presented in this paper covers a period since 1994, which started in the Australian resource industry and since then covered international events. The features of these organizations are summarized as the seven deadly delusions, based on extensiveresearch since 1997 of organizations that suffered unexpected disasters.The Piper Alpha Oil Rig disaster in the North Sea, on the 6 July 1988, was one of the most pivotal events in safety around the world. It changed the thinking and focus of governments, whole industries and led to numerous books and papers. It resulted in new legislation, textbooks and a critical self-examination by the oil and gas industry.In short, an explosion and fire occurred when a pipe started leaking gas and ignited. A temporary flange, with no safety valve, was used to block off this pipe during a maintenance operation the previous shift. The permit to advise operators not to start the pumps on this line was misplaced and lost. Several deficiencies, problems and system failures coincided. A key factor was that the water deluge system was inoperable at the time and failed to extinguish the large fire that erupted, followed by an even larger gas explosion. The accommodation unit, situated on top of the oil rig, was the main "killing field" - most men gathered here to await instructions (which never came) and where they died from smoke inhalation. Later, a large explosion of the gas pipeline from an adjoined rig exploded and killed more people.The line of events and the associated system failures are all very relevant in the analysis of the accident, and provide the only insight into what caused the accident. But much "further back", inside the organization’s culture, lurks more dark matter. The first inclination is to ask what was "deficient" in the culture. Did they not care enough about safety, or about their people? Did they have a culture where production decisions were more important than safety considerations? Did they ‘coerce’ supervisors and employees to ignore safety precautions or did they just "fly by the seat of their pants"?Not surprisingly, it is very difficult to identify the true nature of the culture in that business because in such an aftermath of death and destruction, no one dare say that the safety culture was a ‘positive one, focused and caring’ or that the company was doing well in safety and that this is only a freak accident. Indeed, there were many deficiencies in the organization’s systems and procedures, such as the permit to work system.But there are some niggling questions: How is then that the Piper Alpha Oil Rig was actually considered the company’s most productive and safest oil rig in the North Sea? Why would this rig win a safety competition, 6 months before the disaster, with the deficient permit as its most outstanding successful system?"

Jan 1, 2014

By Andre Vien, Jean-François Dupont

"Over the past several years, Svedala has developed a continuous charge monitor (CCM) for tumbling mills. It consists of a strain gauge embedded into a rubber lifter and associated electronics. This paper describes the installation and use of such a device on a SAG mill at the Holt-McDermott Mine. Comparison to measured static volumetric load and bearing pressure and inclusion of the measurement into a control strategy and its potential for condition monitoring is discussed. INTRODUCTIONWhile the measurement of load is very important in all kinds of grinding applications, the biggest benefits are expected from AG and SAG milling. This is what motivated Holt-McDermott to take a closer look at this problem, with a view to optimizing SAG mill performance.In many cases, the SAG mill control problem can be stated as maximizing throughput while avoiding a volumetric overload, with the other constraints (e.g. power, grind size, upstream/downstream equipment constraints, etc.) playing a less important role. This is certainly true at Holt-McDermott where the SAG mill is the production bottleneck about 90% of the time, and anything that can be done to increase SAG mill throughput will have a significant impact on operating profit.Although the goal of maximizing throughput while avoiding volumetric overload is simple to state, it has proven to be much more difficult to achieve. The mineral processing industry has expended a great deal of time and effort to devise control strategies in the pursuit of this objective. While much progress has been made, there is still room for considerable improvement. Across the industry it is probably fair to say that overloads occur relatively infrequently, but the real losses accrue as a result of the tendency to run rather conservatively."

Jan 1, 2001

By Roger Payne, John R. Goode, Feng Gao, James Brown

The Eco Ridge deposit is located in the Elliot Lake mining camp in Northern Ontario, Canada. Between 1955 and 1996, the area produced more than 138,000 t (300 million pounds) of U3O8 and very significant amounts of thorium and heavy rare earths. Based on the NI 43-101 Preliminary Economic Assessment by Roscoe Postle Associates (RPA) dated June 2012, and the economic review by RPA as announced in Pele Mountains’ Press release dated September 12, 2013, the Eco Ridge Mine Project would extract and process 46 Mt of material to produce about 19,000 t (42 million pounds) of U3O8 and about 65,000 t of rare earth oxide (REO) over a 14-year life. This paper discusses process optimization studies including beneficiation and hydrometallurgical testwork. The proposed modified flowsheet includes the flotation and processing of 1) a pyrite concentrate, 2) a dominantly light rare earth elements (LREE) concentrate, 3) a concentrate containing most of the balance of the uranium and heavy rare earths (HREE), and 4) a relatively inert tailings.

Jan 1, 2014

By Brian A. Ferguson, Raynald O. Vezina, Marielle Gaudet, Raoul R. Boissonneault

"Kiena has been committed to developing a fresh management and employee relations approach since the commencement of production in 1981. The functional organizational structure encourages joint participation and commitment on the part of all employees to common goals in safety and production. The results over the last four years have been extraordinary. Kiena won the John T. Ryan Canada Trophy for 1983 for its safety record and has experienced a steadily increasing productivity through the application of new mining equipment and technology in the hands of a well-trained and motivated team of employees.This paper serves to highlight the fact that productivity, safetyand technical innovation are closely linked to employee participationand involvement which are likely to be the key to theCanadian mining industry&apos;s survival in the years ahead.This presentation follows up on an earlier unpublished paper, given at the 84th Annual Meeting of CIM in Quebec City in April, 1982, which discussed the philosophy and the planning which took place before implementation of the management and employee relations system at Kiena. This present paper reviews and expands on material given in the earlier work. IntroductionThe mining industry, which has always been considered as rather conservative in its approach, has experienced with some regularity, cyclical periods related to metal prices. These cycles, previously foreseeable to some extent have become less coherent over recent years during which time the industry has had to face fierce international competition. The issue to productivity is without doubt the major concern of the mining industry in Canada today and it represents the greatest challenge facing us during the present decade. Developments that have been made in mining technology over the precious two decades have failed to completely produce the significant advancements in higher over-all productivity that were expected."

Jan 1, 1987

By D. W. Zandee

"IntroductionHaving mined an economic mineral bearing rock which is of insufficient grade to warrant direct smelting, upgrading or beneficiation is required to make it an economically viable ore. The first step in effecting the concentration process is comminution or sequential breaking of the rock to allow liberation and subsequent recovery of the desired mineral particles. Desirably the ore could be broken down to the point where the valuable mineral is completely liberated to maximize the chance of recovering as much of it and in as pure a form as possible. The number of energy intensive stages of breakage required to attain this goal depends on many physical characteristics of the ore such as hardness, friability, toughness, grain size, existing fracture planes and particle shapes.Commonly the distinct stages are primary, secondary and often tertiary crushing and finally grinding. To increase the efficiency of each stage of size reduction, pre-treatment sizing is common.Crusher feed is commonly scalped of large pieces or screened for reduction crushers and classified for secondary grindingcircuits.Although crushing and screening is employed for many different products, this chapter reviews current practice in larger tonnage metalliferous ore treatment plants.Current practice is to use large gyratory or jaw crushers for primary crushing and some sort of gyrating or cone crushers for additional stages of reduction. For autogenous or semiautogenous grinding circuits only the primary crushing stage is necessary, the balance of the work being performed in the grinding stage. For conventional grinding circuits using ball mills or combinations of rod and ball mills, secondary, tertiary and even quaternary crushing stages are normally required.Older type crushers such as stamp mills, double rolls, sledging mills and hammermills are no longer common but are used for small tonnage special processes.Important to efficient crushing are a variety of sizing devices such as grizzlies and vibrating screens. Products at different stages must be stored to give surge capacity and allow controlled feeding rates through mechanical and gravity feeders. These storage piles, bins and feeders as well as crushers and screens are commonly integrated into a total facility by means of conveyor systems. Most often these are endless rubber belts driven by simple or multiple drive mechanisms usually consisting of electric motors and speed reducers."

Jan 1, 1989

By N. M. Soonawala

Detailed regional geophysical and geochemical surveys, ground surveys and drilling were undertaken to follow-up the federal-provincial Uranium Reconnaissance Program (URP) over the 27,OOO-km2 Kasmere-Munroe area in northwestern Manitoba. An analysis of the URP data showed a fair correlation between the regional airborne radiometric results and lake-bottom geochemical results, both of which also correlated with the regional geology. More detailed surveys defined anomalies with greater precision within the broad zones outlined by the URP. The ground follow-up indicated that URP anomalies can be caused by varying degrees of uranium concentration in the rocks. Mineralization of interest was found in leucogranites at several locations within the survey area. Anomalous uranium concentrations were also found in coarse pegmatites and Hudsonian granitic intrusions. It can be concluded that large-scale regional surveys can be followed up in relatively short periods of time to yield meaningful results if a properly planned exploration sequence is employed, each stage of which successively narrows the area of interest.

Jan 1, 1979