Search Documents

By W. A. Gow, H. H. McGreedy

It is believed that many of the problems encountered in the operation of gold cyanidation plants are difficult to resolve due to the lack of sufficient and reliable in-formation regarding the variations and actual values of operating variables at any given time. The application of instruments to monitor the more important variables in the cyanidation process should result in more efficient plant operation and a better understanding of the process. The use of pH and conductivity sensing devices for alkalinity measurements, a monitor to determine the dissolved oxygen content of plant solutions, a continuous cyanide titrator and sonic control of grinding circuits are discussed. Although the discussion is oriented toward the cyanide process, much of the paper is applicable to other ore treatment operations.

Jan 1, 1966

By A. H. Lang

"The Cordilleran region of western Canada includes most of British Columbia and the Yukon and pares of Alberta and the Northwest Territories. The western part of this region was for about 50 years the principal mineral producing area of the Dominion. It lost this distinction in 1907 when production from the mines of the Canadian Shield took the lead, but it continues to provide about 15 percent of the total Canadian production. In 1945 the total mineral production of British Columbia and the Yukon was valued at $65,302,900, of which about 80 percent was derived from metals.This paper is intended to serve as an introduction co the more derailed Cordilleran papers. Part I includes a brief synopsis of the complex geology and diverse types of mineralization in the region and Parr II collates the main structural principles exemplified in the derailed papers, and draws some conclusions regarding the application of this information to prospecting."

Jan 1, 1954

By F. Tanaka

Copper losses to discard slag have long impacted on the profitability of copper smelters. Businesses based on the treatment of secondary materials have also revealed that copper losses are indices of precious-metals losses. Many custom smelters are thus required to obtain more reliable controls for reducing copper losses than ever before. Mitsubishi Materials Corp. has cooperated with academic research institutes in conducting research projects on the pyrometallurgical fundamentals of copper smelting systems, including mutual evaluation of magnetite behavior between synthetic and industrial slags. The state-of-the-art pyrometallurgy has subsequently been introduced to Naoshima smelter for controlling the Mitsubishi process. The revised controls function successfully and the operational results demonstrate that avoiding the discharge of solid magnetite from the S-furnace is quite effective to reduce copper losses. Magnetite behavior has been controlled over the Mitsubishi process so as to reduce copper losses while satisfying the needs of recycling businesses growing in Japan. In-situ estimation of magnetite behavior using the absorbed heat from the melts to cooling water will also be discussed.

Jan 1, 2007

By C. Bourgoin

"The factors constraining productivity in the mining of narrow vein ore deposits are numerous and often interdependent. This paper concerns mining techniques capable of reducing some of these constraints in the case of vein deposits whose dip is less than 45 degrees. Modifications of conventional mining methods as well as suggested new developments are presented, as are matters pertaining to the mechanization of operations as a mean of increasing both productivity and work safety. IntroductionThe mining of vein deposits, whose width (thickness) is generally less than 2 metres and whose dip is often variable, calls for the use of varying stoping procedures as well as appropriate infrastructure and equipment. In the case of intermediate dips (15 degrees to 45 degrees), it is generally conceded that the degree of mechanization is limited and that ore removal via gravity is impossible. This paper proposes certain innovations in matters of equipment use and stoping methods, together with certain technical data pertaining to the application of these new procedures Stoping MethodsTo mine vein deposits, one must choose a method that can adapt to irregular ore limits and allow, as well, for good ore recovery with as little dilution as possible. In addition, it is important to minimize development work in waste rock. In principle, one selects a method that is both safe and profitable; this method will be defined mainly by the nature of the vein deposit and its dip, by the competency of the rock formations and by certain technical considerations. Moreover, the stoping procedure in a given deposit may well change with time as a function of new layouts or new equipment."

Jan 1, 1994

The comminution circuit at Tarkwa Gold Mine was commissioned as a Single Stage SAG mill operated in closed circuit with hydrocyclones designed to process 4Mtpa. The circuit was later expanded by adding a secondary ball mill in closed circuit with hydrocyclones with a view to treat 12Mtpa. The change in the circuit configuration and assigning the low aspect ratio SAG mill for primary grinding application makes the Tarkwa experience unique in terms the optimisation strategy and operating philosophy. This paper reports the findings from a series of surveys performed on this plant. The surveys reported include data obtained when the SAG mill was operated as a single stage mill in closed circuit with hydrocyclones and also SABC mode under two different feed conditions. The differences in operating philosophy between the initial single stage SAG circuit and the current SAG/Ball mill circuit are discussed.

Jan 1, 2012

By J. S. Stewart

THIS paper was prompted by a persistent demand for what information we have that will throw light on the oil and gas possibilities of the Maritime Provinces. The problems involved were made familiar to the writer during three seasons of field work in New Brunswick and Nova Scotia. The reasons for renewed interest are: (1) In many parts of that region, the surface is underlain by a thick series of unaltered sedimentary rocks. (2) Oil seepages occur, and oil in commercial quantity has been exploited' near Moncton, New Brunswick, for many years. (3) In recent years, a new method of attack has been developed toward the finding of stratigraphic traps. This method is based on a detailed study of the geological history of the region, as revealed in surface outcrops and samples from deep wells. The well samples show the lateral variation of strata, far from any possible surface outcrop of the same beds. Sufficient work has now been done in the Maritime Provinces to reveal the broad features of the geological history and the character and distribution of the various rock formations. Comparatively little deep drilling has been done in this region, but the holes are widely scattered and the samples from them have added much to the information obtained from the numerous outcrops of bed-rock. The following discussion gives a summary of available information that has a bearing on the subject.

Jan 1, 1943

By A. Todd Davis

"Introduction“CAN YQUR Company afford not to train?"" This question was asked by Jack Taylor in the Factory Management Magazine for June, 1950. Mr. Taylor went on to say, ""No, it can't; no Company can"". It's true that many training programmes have not done the job they were designed to do because of a number of factors such as parts of management resenting training, management failing to understand the abstract values of training, and management giving impossible assignments or picking the wrong trainers. However, Mr. Taylor summarizes his article by saying that a properly-designed and •conducted training programme brings a company or a corporation to the point where the question is: ""Can my Company afford not to train?""About two years ago, in July, 1952, Nevada Mines Division of the Kennecott Copper Corporation embarked on a training programme, the same type of programme that had been inaugurated earlier at the •Utah Copper Division at Bingham, Magna, and Garfield, Utah. President Charles Cox of Kennecott, in •a speech made •before the Utah Bankers Association in June of 1951, stated that, ""I think that our programme of employee training is one of the most important phases of our entire operation"". That statement might be said to be one of the guiding principles of training at Nevada Mines Division. Training is supported by top managements and down the line to Division managements. As the years go by, the Company expects to receive many benefits from training."

Jan 1, 1954

By D. Berkley

Off-gas systems often become the limiting factor in production increase and environmental projects. Any upgrade or new off-gas project needs to address control instability issues, instabilities that can result in safety hazards, significant loss of system capacity and/or emissions to the environment [1]. In addition, the design engineer must optimize system configuration and equipment size for the new operating conditions, to have a technically feasible and economically viable project. Dynamic simulations can be used for addressing both the control stability and the design optimization issues. This paper illustrates how the dynamic simulation of transient processes and of their control system can be used in "real life" situations for these purposes, presenting the example of an electric furnace off-gas system design.

Jan 1, 2005

Research, whether applied or fundamental, is a human endeavour which increases our understanding of nature. It is insufficient to simply observe, explore, record and classify. It i necessary, as well, to fit the observations into a satisfying theoretical scheme; that is, to synthesize. Two examples of successful research programs in physical metallurgy are di cussed from this point of view. A pessimistic view is taken of the prospects for rapid growth of research activities in the Canadian metallurgical industry. THE term "research" is used indiscriminately to describe any intellectual or experimental activity which leads to a change in society. Proponents of various activities, ex-tending all the way from alloy development to subliminal advertising, use the status of the term for special advantage. With the Canadian Government entering upon a project of support to industrial research, it might be well to determine what definition is most in the public interest. As an academic, I have a rather jealous attachment to the definition that research, whether applied or fundamental, is a human endeavour which increases our understanding of nature.

Jan 1, 1963

By Robert Maquil, Gilles Didier, Walter Steiner

"The 1580 m long dual-tube motorway tunnel Markusberg near Schengen, Luxembourg experiences strong swelling phenomena in each tube related to a 35 m wide diagonally crossing rock layer, some150 to 200m from the east portals. Overburden over the roadway is 26 to 30 meters. Tunnel construction started in 1998 and the tunnel was opened in 2003. The tunnel was driven downgrade from the West, the heave phenomenon started to occur as the tunnel approached completion. No indications of the presence of anhydrite and dissolved sulphates were known prior to tunnelling. Water samples had been taken from the beginning of construction and the concentration of anions and cat ions determined. Sulfate content was substantial, in one well it reached 22 mg/l, this high concentration requires the presence of other ions, in particular sodium and chlorine. Based on the knowledge at the time of construction heaving ground was removed from the tunnel invert and a free space was left below the roadway that is covered by a transversely spanned slab. In addition a series of posttensioned tiebacks were installed below the sidewalls. The void left in 2003 was 1.7m high and closed to less than 0.5 meters in 2007 then it became necessary to widen the free space. A central trench was dug with a height of about 2.5 meters and the benches were lowered.Level surveying had been carried out since 2002. In 2006 two extensometers were installed, one in the zone of strongest heave, the second at the edge of the swelling zone. The extensometer in the center of the swelling zone indicated heave with an essential constant rate with seasonal variations, the heave is concentrated in layer from 2 to 5 meters that heaved by nearly 300 millimeters within 5 years or 60 mm/year, which equals to approx. 1% extension per year. At the abutments heave rates of 20 mm/year where the support resistance is higher were observed. With data from other case histories a relation of heave rate with support resistance was established. Based on the numerous field observations hypotheses for the complex in-situ swelling processes, involving rock mechanics, mineralogical, soil mechanics and hydrogeological aspects were developed"

Jan 1, 2015

By M. Fafard, M. Dupuis, P. Goulet, J. Bédard

Start-up of a Hall-Heroult cell is a delicate task that can affect pot performance and pot life. Modem practices for high amperage cells involve preheating the lining before the molten electrolyte is poured in. Different preheating methods and heat-up schedules are used throughout the industry, and the optimum between a short start-up and damage minimization to the cell is elusive. Direct electrical coke-bed preheating is one of the most common techniques. This practice typically results in a non-uniform surface temperature distribution and can generate detrimental thermal gradients in the cathode blocks. Numerical modeling is an invaluable tool to study this complex problem and can help improve the preheating procedures. The modeling of the mechanical response of the lining is critical to detect risks of cathode block cracking or the development of gaps where liquids could leak into. Taking into account the baking of ramming paste, the quasi-brittle nature of carbon and the contact interfaces between different materials are examples of key elements to consider. A finite element slice model of a cell was built and simulations of different electrical preheating scenarios were performed using the inhouse code FESh++ to demonstrate what can be learned through thermo-chemomechanical modeling. The potential industrial application of the model is discussed.

Jan 1, 2006

By Alan Rice

Abstract-The mechanism by which stratiform ore deposits of PGE (platinum-group elements) are laid down in ultramafic igneous complexes is not completely clear. Early studies by the author and coworkers on numerical analyses of the convective cooling of low-Rayleigh-number magma chambers examined the effect of suspended crystal load on fluid density, and raised the possibility that the growth of the suspended crystal load during cooling could split a magma chamber into several convecting layers. The lower layers would have a higher content of refractory phases than the upper layers, which would consist of more evolved melt. This paper considers numerical modelling, as well as theoretical and experimental work in other fields dealing with suspended loads in fluids. The calculations, which are based on the physics of convecting magmas, yield quantitative relationships consistent with the observation that economically interesting stratiform PGE deposits are restricted to large magma bodies, and also yield estimation of the depth in a magma chamber at which certain grades of mineralization may occur.

Jan 1, 1997

By Alan Rice

The mechanism by which stratiform ore deposits of PGE (platinum-group elements) are laid down in ultrama?c igneous complexes is not completely clear. Early studies by the author and coworkers on numerical analyses of the convective cooling of low-Rayleigh-number magma chambers examined the effect of suspended crystal load on ?uid density, and raised the possibility that the growth of the suspended crystal load during cooling could split a magma chamber into several convecting layers. The lower layers would have a higher content of refractory phases than the upper layers, which would consist of more evolved melt. This paper considers numerical modelling, as well as theoretical and experimental work in other ?elds dealing with suspended loads in ?uids. The calculations, which are based on the physics of convecting magmas, yield quantitative relationships consistent with the observation that economically interesting stratiform PGE deposits are restricted to large magma bodies, and also yield estimation of the depth in a magma chamber at which certain grades of mineralization may occur.

Jan 1, 1997

By R. J. Mitchell

"Centrifuge modelling of earth structures is a well-proven technique for evaluating the performance of prototype structures using physical models. The applications of this technique have increased dramatically during the last decade such that even the modelling of dynamic responses in structures has been accomplished.This paper presents the first model test results used to design a mine backfill. The models were tested using a 3 m radius 30 g-tonne geotechnical centrifuge which was constructed at Queen's University specifically for model studies on mine backfill stability and subsidence. The models represent the first production blast-hole stope to be mined at Westmin Resources Ltd. 's H. ~ Mine on Vancouver Island. This paper includes photographs of:model failures in the centrifuge and correlations of model test results with analyses based on unconfined and triaxial test data.IntroductionDuring the feasibility study and development stages for the H.W. Mine, Westmin Resources Ltd. conducted a comprehensive rock mechanics and backfill engineering program. The results of these studies indicated the need for assurance of backfill stability during pillar recovery on the initial blast-hole mining block. The cemented tailings backfill had to be free standing for heights up to 25 m and the potential for surcharge loading from a weak hanging wall zone, the potential for fill block sliding down-dip and the potential for seismic loading had to be considered in the design of the fill strength. The basic questions to be answered were: what cement content is required and will the resulting backfill costs be economic relative to the proposed mining method and sequence? Figure I shows a typical cross-section through the first mining block . The up-dip stope is to be mined first and backfilled with cemented tailings . The down-dip stope would then be mined and filled. Depending on ground conditions encountered, the complete intervening pillar could be recovered and the void backfilled with uncemented tailings or it could be recovered in small sections by exposing limited back and wall areas, backfilling with waste rock and I or cemented tailings . This latter method is commonly referred to as the Avoca method"

Jan 1, 1987

By V. G. Papangelakis, S. Peters

Pressure oxidation of refractory gold ores can be conducted on ores with high carbonate content using just water or water with alkaline reagents to promote fast kinetics, and suppress the formation of elemental sulphur and CO2. In this work, a fundamental study was conducted to explore the silica-pyrite interaction in the presence of calcium and sodium carbonate. It was found that an alkaline environment increases the pyrite decomposition kinetics on one hand, but on the other dissolves silica, which encapsulates the dissolving pyrite thus hindering ultimately its complete decomposition.

Jan 1, 2011

By D. Raicevic

Interest has recently been revived in the recovery of tantalum from the Bernie Lake pegmatite deposit. A gravity concentration process was developed to give satisfactory recovery and concentrate grade. The application of high-intensity magnetic separation was also stud1ed. A pilot-plant investigation that confirmed the laboratory testing and provided a commercial-grade concentrate 1s described.

Jan 1, 1968

By M. Krasowska, K. Malysa, M. Krzan

The paper presents fascinating, in our opinion, observations on mechanism and course of processes occurring during bubble collision with hydrophobic and hydrophilic solid surface. Hydrophobicity of particle surface is a necessary condition for the particle attachment to bubble. We have observed that even in the case of such hydrophobic solid surface as Teflon, the bubble attachment didn't occur at first collision. In distilled water the bubble bounced a few times without attachment. Influence of a-terpineol and n¬pentanol on bubble local and terminal velocity and the phenomena occurring during bubble collisions with hydrophobic and hydrophilic solid surfaces was studied. Bubble collisions with the solid surfaces were monitored and recorded using the high-speed (1182 frames per second) camera. It was found that in distilled water the velocity variations of the "approach-bounce" cycles were identical for Teflon and glass. Four distinct "approach-bounce" cycles were detected both at Teflon and glass surfaces. Moreover, the amplitude and frequency of the velocity variations were identical on collisions with the hydrophobic (polished) and hydrophilic surface. There was no immediate three phase contact formation, with the hydrophobic Teflon surface, what we found really astonishing. Roughness of Teflon surface seems to be important parameter, which affects probability of the bubble attachment as a result of a presence of micro-and/or nano-bubbles at the surface. It was detected that the presence of the micro-bubble affected attachment of the colliding bubble even in distilled water. Presence of a small amount of a-terpineol or n-pentanol affects dramatically the bubble velocity, but their role in mechanism of the bubble attachment needs further study.

Jan 1, 2004

By Andrew Dobson

The assessment and control of environmental noise from mines has become increasingly important in recent years, due to urbanization and population growth, increased regulation of environmental factors, and overall awareness and sensitivities to noise exposure. Minimizing adverse effects on communities and achieving compliance with local ordinances is now commonplace, and consideration of noise during the design and/or operation of a mine cannot be ignored. Ventilation equipment can represent the loudest and most bothersome equpiment at mines, however there are complexities when attempting to control the assocaited noise, due to the acoustical nature of mine vent fans. In fact, the utilization of traditional and/or industry standard methods can intensify the noise impact, or simply not work as intended. This paper provides recommendations on specific noise control methods that are suitable for mine ventilation equipment, based on recent assessment work and field experience.

Oct 1, 2024

By K. Adham

Both the dry and the wet fluorination systems require hydrogen fluoride (HF) for the process of uranium conversion to uranium hexafluoride (UF6). The dry methods depend on the electrolysis of HF to generate the fluorine (F2) required for the high temperature pyro-fluorination. The wet methods require aqueous HF in water solutions for the low temperature hydro-fluorination (Argonne, 2019). This paper uses the available HF safety guidelines and industry information to discuss the issues of transportation, storage and utilization. Health effects and environmental considerations are reviewed. Safe practices for handling the HF (both as anhydrous and as aqueous) are considered. Proper selection of different materials of construction are discussed, for both the anhydrous and the aqueous HF.

Jan 1, 2020

By Kazuhide Nakaniwa

In this research, we devised a measurement method using total stations (TSs) which have ?the Baum? which is a concentric circle reticle, as substitute for crosshairs. The Baum owes its name to the similarity between the concentric circles and trees (Baum in German). By setting one circle on both of edges of cylinders, operators can set their sights on points on the center line of the cylinders, and also can measure positional coordinates of the points. Also, by measuring two different points on the center line, operators can measure the position and tilt of the axes of the cylinders. Furthermore, we developed a pile driving navigation system. Foundation piles are used for various structures, and their forms are generally cylindrical. Especially, although it is difficult to drive tilted pile foundations, their usage are expected to expand due to their high earthquake resistance. Yet, a method to accurately measure the tilts of piles has not been established. However, we proved that operators can obtain adequate accuracy to control foundation piles through the measurement experiment using this system. Using this system, the information of the pile is measured using a TS, transferred to a PDA, and displayed from the operator?s view of the piling machine.

Aug 1, 2013