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By Thomas J. Ferree

"There has been a major evolution of mineral processing technology in the past decade. The evolution has been driven by recognition of broad environmental changes which have impacted various areas of the world. Numerous government regulations have required many mining and mineral processing organizations to introduce changes to reduce the undesirable effects on the environment; many mining companies have voluntarily introduced new technologies and practices which surpass the limits imposed by the regulations. Surprisingly, some of the 'new' technologies are modifications of concepts developed decades earlier. Gravity separation technology is in this category.Mineral Deposits Limited, an Australian company, has been a world leader in the development of mining concepts, reclamation practices and equipment technology that is environmentally suited to today's requirements. This paper relates to equipment used for gravity concentration and electrostatic separation systems, including Reichert cones, spirals, and electrostatic separators. The basic devices and technologies were developed more than forty-five years ago, but use of the systems was quite limited until environmental and conservation practices were recognized and introduced. Spiral concentrators, for example, were patented in the mid-l940s by I.B. Humphreys in Denver , Colorado. The two types of spirals marketed (the Model 24A for minerals and the Model 24C for coal) remained essentially unchanged until expiration of the patents. During this early period most spirals were used in iron-ore wash plants on the Mesabi Range to recover fine iron which previously had been discarded. About the same time sand mining plants in Florida incorporated spirals to recover titanium minerals and zircon from lowgrade beach sands. The Labrador Trough opened new opportunities for spirals when hard-rock iron-ore deposits were developed; approximately 10 000 Model 24A Humphreys spirals were installed between 1958 and 1966. About 5000 spirals of this model are still operating in the same capacity, in spite of the fact that extensive improvements have since been made in gravity separation technology."

Jan 1, 1993

By G. Pouskouleli, T. A. Wheat

"The role and benefits of using statistical methodology in the development and optimization of materials and processes is examined. It is shown that considerable benefits accrue from the use of an appropriate design in which a number of factors (process parameters) are varied simultaneously while the system response such as percent recovery, degree of separation, purity, etc. is monitored and ultimately optimized.Compared with the commonly encountered one-factor-at-a time approach, this schema exploits reduced experimentation (thereby requiring reduced resources [staff, time, dollars, etc.]) yet yields quantitative information on the significance of each factor and their combinations on the measured response."

Jan 1, 1992

By J. R. Pronovost, P. M. Tiley, D. W. Watts

"In 1980, J.S. Redpath Limited were retained by Dickenson Mines Limited to increase hoisting capacity from 700 to 1000 tons per day. The hoisting capacity of the present skip-over-cage system could not be increased significantly through design modifications. The other constraint was a minimum of disruption to the current production. The Dickenson shaft was a three-compartment shaft from surface to the 8th level and four compartments before the 8th to the 23rd level. The solution to the problem was to remove the services from the shaft man-way compartment from the 8th level to surf ace by drilling a borehole close to the shaft and rerouting those services through the borehole to the 8th level. A service compartment would then be available from surf ace to the 23rd level.By providing a service hoist in this compartment, the skip hoist would then be free to produce the 1000-tons/day required production. This paper will describe the search for the required hoist and the friction hoist selected for the project, and trace the design modifications required to modify the hoist to suit the Dickenson application and satisfy the Department of Labour safety requirements.The paper has been co-authored by J.S. Redpath Limited and C.L. Tiley Associates, who participated in the design changes and eventual commissioning of the hoist.IntroductionIn the earl y part of 1980, J.S. Redpath Limited conducted an engineering study on the Dickenson Mines Limited No. 1 Shaft materials handling system. The object of the engineering study was to investigate the possibility of increasing the tonnage hoisted from the No. 1 Shaft complex by adding a service cage compartment and service hoist. This would permit utilization of the existing hoisting plant solely for production hoi sting. A further consideration of the engineering study was that any alterations had to be accomplished with little, or no, interruption to production."

Jan 1, 1982

By J. R. Pronovost, P. M. Tiley, D. W. Watts

"In 1980, J.S. Redpath Limited were retained by Dickenson Mines Limited to increase hoisting capacity from 700 to 1000 tons per day. The hoisting capacity of the present skip-over-cage system could not be increased significantly through design modifications. The other constraint was a minimum of disruption to the current production. The Dickenson shaft was a three-compartment shaft from surface to the 8th level and four compartments before the 8th to the 23rd level. The solution to the problem was to remove the services from the shaft man-way compartment from the 8th level to surf ace by drilling a borehole close to the shaft and rerouting those services through the borehole to the 8th level. A service compartment would then be available from surf ace to the 23rd level.By providing a service hoist in this compartment, the skip hoist would then be free to produce the 1000-tons/day required production. This paper will describe the search for the required hoist and the friction hoist selected for the project, and trace the design modifications required to modify the hoist to suit the Dickenson application and satisfy the Department of Labour safety requirements.The paper has been co-authored by J.S. Redpath Limited and C.L. Tiley Associates, who participated in the design changes and eventual commissioning of the hoist.IntroductionIn the earl y part of 1980, J.S. Redpath Limited conducted an engineering study on the Dickenson Mines Limited No. 1 Shaft materials handling system. The object of the engineering study was to investigate the possibility of increasing the tonnage hoisted from the No. 1 Shaft complex by adding a service cage compartment and service hoist. This would permit utilization of the existing hoisting plant solely for production hoi sting. A further consideration of the engineering study was that any alterations had to be accomplished with little, or no, interruption to production."

Jan 1, 1982

By J. G. Bensley, K. S. Detheridge

"Many plants use computers for process control and most have computerized Management Information Systems but few have been able to have these systems interact with one another. Developing this system interaction is not a one-step process but requires careful planning and implementation. This paper describes two projects that were implemented to provide the bridge between the process control and management information systems of Cominco Limited. Both projects include the replacement of essentially process control systems installed in the late 1960s. These original systems provided an enhanced level of control in the form of Direct Digital Control (via computer/manual analogue control stations) and a management reporting capability of process data. The experience gained from the use of these systems over a period of fifteen years formed a basis for the evaluation and planning for the new systems. The new systems were commissioned in 1985 and 1986 and operating and further developments leading to a totally integrated process information and control system are underway. INTRODUCTIONThe concept of hierarchical control involves a control structure consisting of a number of defined levels. Each level performs a defined function with information consolidated and combined as it moves up through the hierarchical structure. The commonly accepted structure of a hierarchical control system echoes the structure of the plant which is being controlled. Referring to Figure 1:Level 0 - Sensors and ActuatorsSensors and actuators, such as thermocouples and flow control valves, interface directly to the process and are generally connected directly to the controllers or multiplexers at Level I.Level 1 - Regulatory ControlThis level provides basic PID control (proportional/integral/ derivative) typically using microprocessor based controllers and programmable controllers for digital control of motors and machines. Systems at this levelare usually segregated by plant unit, e.g, crushing, flotation, drying. Control is concentrated on achieving optimum conditions for a particular feed rate."

Jan 1, 1989

By William M. Luff

"The Bathurst area has recorded mining production as early as 1837, although the bulk of the production has come in recent years. Production has been mainly from the well-known massive sulphide deposits, but vein, gossan, and a variety of other deposits have also been mined. This paper summarizes the history of the mined deposits, along with tonnages and grades produced.A number of ""firsts"" have been noted in the Bathurst area. The A Zone deposit, located in the Heath Steele area, was the first in the world discovered using airborne electromagnetic methods. Heap leaching of gold from the gossan zone at Caribou was the first operation of its kind in Canada. The Keymet mine was the first base metal (lead-zinc) mine in New Brunswick. For the past few years, the Brunswick No. 12 mine has been one of the largest zinc mines in the world.IntroductionThe Bathurst area (Fig. I) first had mining production in 1837 when copper was mined from a deposit on the Nepisiquit river (MacKenzie, 1958). The majority of the production, however, has been in recent years from massive sulphide deposits, but there are also other significant operations.Table I is a summary of Bathurst area mineral production, showing concentrator feed tonnages and mill feed grades. The table does not include peat deposits, sand and gravel, dimension stone or rock quarries. Figure I is a general geology map of the Bathurst area, indicating deposit locations. The deposits are divided into four categories: massive sulphide, vein, gossan and other. The deposits in each category are described in chronological order of exploitation."

Jan 1, 1995

By Dieter Birk

"The Atlantic Coal Institute illustrates the potential for high technology employment in Maritime Canada, by using local talent and the latest equipment to address a national market. Since I983, contract research for industry and government has generated 31 man-years of high-tech employment, added $2.3 million to the local economy and contributed new technology for Canadian coal. Industry now has access to new procedures for coal minerals analysis, pyrolysis, and geochemistry applied to industrial problems of exploration, beneficiation, conversion and combustion.Research at the Institute is market-driven, based on cost recoveries from contracts. The financial performance to date exceeds that of similar industrial research institutes in major cities and demonstrates that small isolated laboratories are cost-effective. Economic renewal of Canada's resource industries will require increased R&D which in turn can be a source of local employment and pride. Small research teams are more efficient but require an enlightened policy of contracting-out by big business and big government."

Jan 1, 1987

By M. K. Abel

"The Strathcona Mine is located in Levack Township on the North Range ofthe Sudbury Basin. The main orebody consists of pyrrhotite-pentlandite-chalcopyrite mineralization associated with an embayment of the footwall of the Sudbury Irruptive. A zone of massive chalcopyrite-cubanite-pentlandite mineralization occurs in a complex vein system in a series of mixed gneisses and breccias in the footwall. Vein widths vary from a few millimetres to 6 metres. In December 1979, this zone was estimated to contain 976,000 metric tonnes, with a grade of 9.31% Cu and 0.46% Ni. The vein system has a general strike of N 68°W at an angle of 60 degrees to the average strike of the footwall contact of the Irruptive. The dip of the vein system is 45 degrees sw. The strike and dip of individual veins in the system coincide with the directions that would result if a compressive stress had acted in a direction normal to the footwall of the Sudbury Irruptive, producing a conjugate set of fractures. The strike of the Irruptive at the Strathcona Mine is parallel to the long axis of the basin.IntroductionThe Strathcona Mine, owned and operated by Falconbridge Nickel Mines Limited, is located in Levack Township on the northwest rim of the Sudbury basin (Fig. I) . It is one of a group of nickel-copper sulphide ore deposits present along an 8.2-km section of the North Range of the Sudbury Irruptive. In the mines of the North Range, subunits of the Irruptive, going from hanging wall to footwall , include felsic norite, dark norite and dark norite breccia. The footwall complex at Strathcona includes the late granite breccia, which hosts a large proportion of the nickel-copper ores, and a compositionally variable group of brecciated and migmatized rocks, herein referred to as the feldspathic gneiss complex. It is within this latter group of rocks that the vein system of the Copper Zone occurs."

Jan 1, 1981

By Henry Smith, Stu Brown

"The Williams Mine is Canada's largest gold producer, with annual production of some 500 000 ounces of gold from two million tonnes of ore. Highly mechanized and automated underground mining practices are utilized at the property in order to help achieve high levels of productivity and the most cost-effective mining possible.Planning and design parameters for the underground ore handling system at the Williams Mine are described in this paper. Particular reference is made to the considerations that were built into the system to provide maximum operating flexibility through the use of multiple orepass systems, portable low profile jaw crushers, underground conveyors and automated hoisting equipment.IntroductionThe Williams Mine is situated in the Hernlo area of northwestern Ontario, approximately 40 Ian east of the town of Marathon (Fig. I). It is operated by the Williams Operating Corporation, which is owned equally by Teck Corporation and Corona Corporation, and is one of three adjacent properties forming the HernIo gold camp.The mine commenced operation in October 1985 at a nominal production rate of 3000 tpcd. Through an ongoing capital development program, winch was completed in late 1989, the production rate at the property was increased to its current level of 6000 tpcd. This paper describes the mine planning process and the evolution of current mining strategies with particular reference to the underground ore handling system .HistoryGold mineralization was discovered in 1944 in the Hemlo area of Northern Ontario, near the north shore of Lake Superior. A year later, 11 claims were staked over the showing and subsequently patented by the late Dr. Jack Kerr Williams.Over the next 35 years, other claims were subsequently staked, explored and abandoned in the immediate area of the 11 patented claims . In 1980 a predecessor of the Corona Corporation acquired claims adjoining the Williams property to the east. Drilling on this claim group started early in 1981 and intersected the Hemlo orebody in May of that year. In December 1981, Corona Corporation entered into an option agreement with Teck Corporation to explore and develop the property.A drilling program by LAC Minerals on the II patented claims discovered the Williams orebody in March 1982. The mine started production in 1985, pouring its first official bar of gold on December 6 of that year. Corona Corporation was awarded ownership of the Williams Mine conclusively by a decision of the Supreme Court of Canada on August 11, 1989. The court's ruling ended a legal dispute with LAC Minerals over the property initiated eight years earlier."

Jan 1, 1991

By X. Grant Chen, A. R. Farkoosh, M. Pekguleryuz

Nano-scale Al-(Fe,Mo)-Si dispersoids form during solution treatment in grain interiors (intradendritic regions) of cast Al7Si0.5Cu0.3Mg alloyed with 0.3Mo (wt.%). Unlike the Q-Al5Cu2Mg8Si6 and ?-Al2Cu age-hardening precipitates which coarsen resulting in loss of strength in Al-Si-Cu-Mg alloys, these Mo-containing dispersoids are thermally stable and retain their strengthening effect at elevated temperatures. Consequently, the age-hardened Al7Si0.5Cu0.3Mg0.3Mo (wt.%) exhibits high strength and creep resistance at 300 °C.

Jan 1, 2014

By Pierre Beaudoin, Michel Bourassa, Robert Lanthier, Samir Chéfaï

"Mine Doyon, in collaboration with CRM's Process Control Division, improved the control strategy at the SAG mill I Ball mill grinding circuit. The project aimed at increasing operation stability and throughput. First, a needs analysis was achieved in order to define the control philosophy and to upgrade the process control equipments and instrumentation. The stabilizing control strategy has been developed and implemented successfully using single loop PID controllers. The monitoring feature as well as the rule based supervisory control strategy were implemented on 486PCs running Process Vision and COMDALE/C softwares. Main features of the control strategy are described in this paper while results are presented and discussed.RésuméLa Mine Doyon, en collaboration avec le service de contrôle des procédés du CRM, a optimisé la stratégie de contrôle au circuit de broyage. Les objectifs du projet étaient !'amélioration de la stabilité de !'ensemble de !'opération et la maximisation du tonnage usiné. Une analyse de besoins a été réalisée pour concevoir la philosophie de contrôle et déterminer les ajouts a apporter a I 'instrumentation et au systeme de contrôle. Une stratégie de contrôle à deux niveaux, integrant stabilisation et supervision, a été developpee et mise en opération. La regulation est réalisee par une combinaison de contrôleurs Moore de type PID. Le monitoring et la stratégie de contrôle a base de règles soot implantés sur des micro-ordinateurs de type PC/486 avec les logiciels ProcessVision et Comdale/C. Les principaux aspects de Ia stratégie de contrôle sont décrits dans cet article et les résultats obtenus soot présentés et discutés."

Jan 1, 1995

By D. R. Spink, G. L. Rempel, C. O. Gomez Bueno

"A morphological and chemical study of the Great Canadian Oil Sands Ltd. (GCOS) fly ash has been carried out. Extensive scanning electron microscopy, as well as light microscopy, showed that the GCOS fly ash consists of two fractions, one composed of unburnt or partially burnt irregular-shaped carbon particles and an ash fraction composed of transparent and opaque, often coloured, glassy spherical particles-some of them cenospheres (hollow spheres) and the others plerospheres (hollow spheres packed with smaller spheres). Microcrystals (0.1 to 0.3 um long) growing on the inner and outer surfaces of some of the spheres were also noted and found to contain more Fe, Ti, Ni and V than the spheres.The carbon-free GCOS fly ash particle size follows a lognormal distribution, with a geometric median particle size (by count) of3.8um and a geometric standard deviation of 1.84. IntroductionCanada's current energy situation strongly suggests that oil from the Alberta tar sands deposits will probably be recovered more extensively in the future. Today's commercially proven technology to recover oil from the Athabasca tar sands, as practised by Great Canadian Oil Sands Ltd. (GCOS), involves two major operations, namely: separation of the bitumen from the sand and upgrading of the bitumen to refinery oil; the production of significant amounts of petroleum coke and sulphur during the bitumen upgrading process. The bulk of the petroleum coke is burnt in boilers to fulfill the energy requirements of the entire operation. The boiler ash, which contains appreciable amounts of metals, such as vanadium, nickel, titanium, iron, aluminum and other elements, is collected in the boiler hoppers and cyclones of the petroleum coke-fired steam generation plants. Thus, as well as representing a petroleum resource, the tar sands represent a resource for vanadium and possibly other metals providing that metal recovery processes can be developed."

Jan 1, 1980

By Eric R. Skonberg

"Technology exists today to blind drill a mine shaft 20 feet in diameter, unlined, over 3,000 feet deep. These shafts must be lined in the most economical, safe and expedient manner possible. A new technique of stacking precast concrete cylindrical sections in the unlined shaft has been developed to yield a dry and hydrostatically lined shaft .These sections must withstand an external radial pressure of 3,000 feet of water yet take up as little room as possible in the shaft . Using high-strength concrete, wall thicknesses may be kept at 2 feet. The outside diameter of the sections has been chosen to be 18 feet to allow for some annular space between the liner and shaft wall. The concrete sections are produced in segments 10 feet long weighing 75 tons each. During drilling operations, the concrete sections are cast and cured. After drilling operations are complete, a headframe is situated over the shaft. The unlined shaft remains full of fluid. A special liner running tool is mated with the section in three steel ports at the bottom of the section. The section and running tool are lowered into the hole, and the tool is disconnected and returned to the surface. Subsequent sections are lowered and stacked using the same operation. Grout is placed behind the liner to result in a dry shaft."

Jan 1, 1981

By M. Mahdi, L. So, A. MacMillan, D. Metcalfe, J. Woloshyn, D. Sauter, N. Uys, JP. Janse van Rensburg

For city smelters, with limited real estate, efficient slag cleaning furnaces followed by water granulation to produce an iron silicate product is the preferred process approach. Water granulation, however, consumes large volumes of water and requires high maintenance due to abrasive slag/water slurries. Air granulation offers an alternative to water granulation, which eliminates water use and has low maintenance requirements. Although full-scale operation has not been implemented for copper slags, full-scale operation for platinum group metal (PGM) converter slag has been implemented. A review of full-scale air granulation performance for PGM converter slag is provided. Based on PGM converter slag granulation performance, parallels to copper slag granulation are drawn and full-scale operation for copper slag is modelled using computational fluid dynamics (CFD). INTRODUCTION Typical slag management practices in the copper industry include dumping, slow air cooling, and water granulation, as shown in Figure 1. Dumping is the most commonly used slag handling method for most metal production plants, but presents challenges including the requirement for a large slag pit, requirement for expensive/high-maintenance “hot” mobile equipment, risks associated with transportation of molten slag, and no value recovery from slag as a sellable by-product or from slag as a source of heat.

Jan 1, 2019

By S. Zador

"IntroductionIn the past decade, metallurgical and mining companies have shown an increased interest in the licensing of technology. When licensing technology, it is usually to the benefit of the parties, to have at least some of the technology to be licensed protected by a patent.This paper is intended to bridge the gap between the engineer in the field of mining, metallurgy and mineral processing who is interested in exploiting an invention commercially, and the patent agent or intellectual property lawyer whom he/she might retain to prepare a patent application and then prosecute the application to obtain a granted patent. It is also intended to encourage the inventor or a small business concern to consider the value of patents in the sale and licensing of technology. The lawyer may subsequently advise and assist the inventor in licensing his/her invention.A brief outline of some of the basic features of the patent system follows. The nature of the information, which the patent professional requires from the inventor to enable him/her to draft a patent application, will also be considered in general terms. Furthermore, various types of licenses which may be drawn up between a licensor of specific technical information and a licensee, will be listed and briefly discussed. No attempt, however, will be made to give a comprehensive and detailed account of the above aspects; the interested reader should consult legal publication and reference books, and patent professionals for further specific information.A granted patent is a document which describes an invention and how to practise it. The claims of the granted patent, figuratively speaking, fence off the intellectual property the inventor regards as his invention. The Commissioner of Patents, representing the Government, grants to the inventor or his assignee the exclusive right of making, constructing and using the invention, and selling it to others to be used, for a limited period of time, in exchange for disclosing the invention to the public. Thus, a patent prevents others from practising the claimed invention but it does not, necessarily, bestow the right to the patentee to practise his own invention. The term of a patent now in Canada and in most of the developed countries of the world, is 20 years from the date of filing the patent application. In the United States the patent term is still 17 years from the date of issuance of the patent. In Canada, the term was changed to 20 years in the new Canadian Patent Act which came into force on October 2, 1989. Any patent application filed prior to that date or granted before it, retains a 17 year life, commencing at the time of grant."

Jan 1, 1991

By N. Lecuyer

"During early 1980, pre-production work commenced at the ""Les Mines Gallen"" project, north of Noranda, Quebec. As a result of the acid mine water associated with this property, a major pre-production phase included the installation of a water treatment plant to render the water environmentally suitable.This paper emphasizes the planning, installation and operational factors of the treatment plant necessary to the success of the mining operations and the maintaining of a clean environment.Introduction,T he Gallen Project is a zinc, gold and silver open-pit mining operation approximately 10 kilometres north of Noranda, Quebec. This property has a long history, with initial diamond drilling done in the early 1930s and underground mining taking place between 1953 and 1962. This property was reactivated in 1980, with production scheduled a t a rate of 45,000 ton s per month.Included in the reactivation plans for the property was the installation of a water treatment plant to treat the acidic mine water.Plant DesignThe requirements for the Gallen water treatment plant were two-fold. Firstly, it was necessary to neutralize the acid water and secondly to produce a sludge containing metal hydroxides and sulphates which would be stable when stored, and a clarified overflow meeting governmental regulations to be discharged to the environment.The flow sheet (Fig. I) will explain the process in treatment of the acid water.Acid mine drainage is treated with lime to increase the pH to 9.50. Metals in solution are precipitated as metal hydroxides and the 504 as calcium sulphate. The precipitate slurry is then aerated to convert ferrous iron to ferric iron, which is more stable for storage and disposal.The precipitate is next flocculated with a polymer flocculant and settled in the thickener to produce a sulphate/Hydroxide sludge and a final effluent discharged to the environment."

Jan 1, 1983

By Douglas A. Sloan

"Recently, a number of major mining companies seemed unable to find a president from within the industry, and were searching outside the industry. From this, one could conclude that managers within the industry are either not being prepared or are not preparing themselves for presidential responsibility. Opinions were sought from a number of senior executives, to attempt to define the skills a prospective president should acquire and what actions a company could take or that a prospective president could take to acquire these skills.This paper contains summaries of the opinions obtained, along with the author's comments. The paper also describes the actions some companies are taking and the actions that an aspiring president can take to prepare himself for corporate management.IntroductionA manager is promoted up the management ladder when the manager's superiors believe that he is capable of handling a more senior position. Normally, the manager acquires this credibility by outstanding performance in his current management post, whether it be in a junior management (supervisory) or in a vice-presidential capacity.In most instances, the skills required for promotion can be acquired in the current position or, at worst, the abilities exhibited in a candidate's current role will convince his superiors that the necessary expertise for the more senior position can be acquired on-the-job. This is particularly the case when the new skills are felt to be an extrapolation of the old skills.However, in the case of appointment to presidential rank, there appears to be a need for new expertise which often is not acquired in normal management progression or, at least, boards of directors of some mining companies seem to believe this to be the case. The objective of this paper is to attempt to define the new skills that should be acquired by a manager who aspires to be the president, and to describe what actions might be taken by him to acquire them."

Jan 1, 1982

By George J. Simandl, Suzanne Paradis, Kirk D. Hancock, Jana Simandl

Traditional prospecting and boulder tracing are the two most important field techniques used in exploration for magnesite deposits hosted by sedimentary rocks. Consequently, success depends largely on the prospector's ability to identify magnesite. A density agent called sodium polytungstate (3Na2W04·9WOj'HPJ was successfully used to determine the presence of magnesite in sedimentary carbonate rocks of southeastern British Columbia. A rapid field method was developed and tested. This method permits discrimination between limy dolomites, dolomites, magnesite-bearing dolomites and magnesite-rich rocks.

Jan 1, 1993

By E. L. Day

"In the early 1930s during the course of test work with a simple gold ore, it was evident that the time required to dissolve the gold by cyanidation was very much longer than should have been needed theoretically for the maximum size gold particles in the ore, A similar conclusion appeared to be valid for other gold ores. In a cyanidation system there are many factors which can influence the dissolution rate of gold, and a decision was made to investigate the more obvious variables, because a literature survey at the time showed that with the exception of the work of Yamazarki on the dissolution of silver in cyanide solution, virtually no attention had been given to this subject, Our work was not reported because the intention was to do this on completion of the Study, but owing to the demands on the Section's personnel for other work the investigation was never completed. Although other investigators have since studied the problem, the methods which we adopted and some of the conclusions may be of interest to metallurgists concerned with gold ore treatment.Form of GoldExperiments with gold ores were not possible because of the number of uncontrollable variables present in a gold ore-cyanidation system, therefore pure metal and reagents were used. Initially some experiments were carried out with gold leaf, but it was soon apparent that metal in this form was unsuitable because the uneven thickness of the leaf caused it to break up into pieces and. there was difficulty in determining precisely when complete dissolution had taken place, Numerous factors both expected and unexpected were found to influence considerably the results and much experimental work was necessary to establish the procedures which were finally adopted, Experiments were carried out with gold in the form of foil, wire, rings and sols. Finally, gold foil in the form of cylinders was adopted for most of the experiments although some work with gold in the sol form was included in the programme. Also some experin1ents were carried out with a gold ore to see if effects which were obtained with sodium chloride on gold sols were applicable to gold ores."

Jan 1, 1967

By D. Kao, J. Gogal, S. Humphrey, T. Byrne, M. Davoodi

"High total and dissolved uranium values were noted in the process water at the Cigar Lake Operation (CLO) during early production start-up period, whereas significant levels of dissolved uranium had not been observed previously at similar operations. The excess dissolved uranium resulted in higher demands on the water treatment plant, along with higher operating costs, environmental risks and some unrealized revenue potential. A species balance indicated that uranium was leaching into solution in the grinding, dewatering, and storage circuits under normal operating conditions. Jet boring, water recycle, ball milling, and the use of Pachuca tanks for ore storage results in a highly oxidative environment, which is favourable to leaching.This paper will outline the testwork performed to identify the conditions under which the uranium leaches into solution and to determine required conditions for uranium precipitation. Maximum uranium leaching was found to occur under normal operating conditions (pH ranging from 7.0 to 8.5); testwork indicated that both lowering and raising the pH can significantly reduce the uranium leaching. Analytical results combined with the batch scale testwork indicate that the uranium solubility is associated with carbonate species in the ore. Uranium precipitation was maximized at pH values greater than 10.5 or less than 6, corresponding well to carbonate leaching and precipitation values from literature. Higher precipitation efficiencies were noted at high pH ranges.As a result of this work, a pH control system has been implemented in the Pachuca storage vessels and thickener prior to water treatment plant on a trial basis. Caustic soda is recommended for pH control due to ease of operation, economic viability and material requirements and downstream constraints."

Jan 1, 2016