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By Hilden. M.

"As the Cadia mill was the first 40ft diameter SAG mill, commissioned in 1998, its performance, liner and discharge design attracted considerable international attention. Twelve years on, the liner design and the control philosophy are being readdressed to further improve the mill’s performance. A comprehensive series of 3D liner scans, over life of the liner, have been used to calibrate liner mass loss and progressive changes in the liner profile. This data is being used to provide true charge mass and mill filling, plus progressive trajectory profiles over life of liner. This information, along with measures of mill performance over liner life, is being used to select the optimal operating conditions as the liner wears, and hopes to inform future liner design. INTRODUCTIONSince the Cadia mill was the first 40ft diameter SAG mill, its performance, liner and discharge design has attracted considerable international attention, as reported in previous SAG conferences. The mill experienced particular challenges with regard to pebble and slurry discharge, which necessitated a discharge redesign, incorporating a considerably greater pebble port open area and curved pulp lifters (Hart, Valery, Clements, Reed, Song & Dunne, 2001). Packing between lifter bars on the shell liner was found to dramatically reduce mill throughput over the first half of the liner life. In response, the liners were redesigned to a 2/3 spacing so as to open up the space between lifters. Due to ongoing high liner wear issues, the liner was redesigned based on the discrete element modelling (DEM) of Conveyor Dynamics conducted by Nordell and Potapov (2001). This aimed to maintain mill throughput with new liners and provide an extended liner life. This design was kept proprietary for many years, so has not been open to review."

Jan 1, 2012

By A. Taylor

This paper considers mineral processing in zero gravity dry environments typical of asteroids or comets. The electro-dynamic separation technique using pneumatic flow systems is explored. Pneumatic delivery of solids is used because of extreme temperature changes and the possible scarcity of water. The present earth-based process and how it can be modified for these conditions is examined.

May 1, 2001

By R. D. Brown

For the first time in years, the spring budgets of federal and provincial governments have not brought down major new proposals affecting the tax burdens of the mining industry in Canada. It seems appropriate to use this unaccustomed period of tranquility to set out an extremely abbreviated summary of the principal features of the federal and provincial income and mining tax rules affecting the mining industry.

Jan 1, 1977

By M. C. Villeneuve, P. A. Siratovich

We present an integrated analysis of laboratory-based thermally induced fracturing and results of numerical models to give insight to the role of thermal shock fracture on geothermal reservoir rocks. Thermal stimulation is a reservoir permeability enhancement technique applied to commercial geothermal reservoir rocks to enhance fluid injection capabilities for spent power plant working fluids. The process is well known to enhance permeability but the thermodynamic and physical constraints of the process are less certain. In an attempt to constrain the interaction and the ideal conditions that lead to permeability enhancement, experimental procedures were carried out to mimic the conditions that a reservoir rock would experience during a thermal stimulation using temperature differentials ranging from 50-300°C. Samples underwent such thermal gradients under controlled laboratory conditions and were characterized for the changes to permeability, porosity, ultrasonic velocities, dynamic elastic moduli and petrological changes. The thermal stimulation was simulated in a FLAC2D thermal numerical model to investigate the nature of the thermally induced changes in the sample. The development of this model also allows us to investigate the relationship between geological characteristics and the ability to thermally stimulate any type of rock. The results indicate that numerical thermal shocking experiments are corroborated by laboratory-based results. The implication of this study is that the refined numerical models present an insight to the conditions and constraints under which thermal stimulation can prove to enhance permeability that could not be gained through purely laboratory-based studies.

Jan 1, 2015

By A. J. Vivyurka

"This is a talk about the experiences that Rio Algom Mines Ltd. has had in the Elliot Lake uranium area trying to make the tailings more compatible with the surrounding environment. To get a better idea of the problem that we are associated with we have to go back to the location. The Elliot Lake uranium area is situated about half way between Sault Ste Marie and Sudbury and is about 20 miles north of Lake Huron. In 1950, uranium was discovered along the north shore of Lake Huron and by 1961 we had up to 9 mines operating in the area. Then the United States Atomic Energy Connnission withdrew their contracts so that at present there are only 2 mines operating. From all the mines that we had operating, we ended up with 7 tailings areas. From these 7 tailings areas we have 5 sites where we have active treatment or rehabilitation. There is the Pronto site where we are treating uranium tailings and copper tailings. There is the Lacnor-Nordic site which is located just out of Ellio Lake. The Milliken-Stanleigh site is in the Crotch Lake area. The Panel tailings is off the north end of Quirke Lake and finally there is the operating property of Rio Algom Mines at Quirke Lake.To understand fully the problem with this rehabilitation we have to look at the constituents of the ore. The ore body is a quartz conglomerate with uraninite and brannerite as the uranium bearing minerals in a fine ground mass of quartz, sericite and pyrite which separates the larger quartz pebbles. The approximate composition of the ore is: 80% quartz, 13% chlorite, 7% pyrite and 0.2% uranium minerals. The processing method also adds a few constituents to the final tailings."

Jan 1, 1975

By R. A. Horn, S. M. Telfer

"Canada has a per capita GDP second only to Japan among the G7 countries and a positive trade balance which ranks third among the world's major economies. International trade represents a very large part of the national economy and as a proportion of GDP is larger than that of all the other G7 countries with the exception of Germany. On the negative side the Canadian current account deficit relative to the size of the economy is significantly worse than that of all major industrial countries, due mainly to the cost of servicing an immense foreign debt and to a large and worsening negative trade balance in manufacturing.The outflow of money may be reduced by increasing the productivity and competitiveness of those sectors of the economy in which Canada already has a leading competitive position and which have the potential for further growth. The mining industry is uniquely qualified in this respect in that Canada is the western world's largest producer of metals and mineral products and has the geology and the exploration skill to replenish reserves assuming that an adequate level of investment is maintained. In 1989 the minerals industry contributed $8 billion to the country's balance of payments and with the exception of forestry is the only sector of the economy which has shown consistently increasing foreign earnings over the long term.In recent years there has been a decline in exploration in Canada and a significant increase in countries such as Chile. The demand for hard currency to finance the development of the newly emerging capitalist economies of the CIS and Eastern Europe is also driving these countries to seek foreign investment to allow them to exploit their natural wealth more efficiently. Canada is therefore facing growing international competition for risk capital and in the future its trade surplus will probably decline in the face of lower cost foreign production.Canada rightly exercises a high level of environmental control on its mining operations; however a significant deterrent to investment is the fundamentally unjust application of the many provincial and federal environmental laws, under which a mining company, even if it takes every measure to protect the environment, runs the risk of eternal and unlimited future liability. If this situation is not rectified the effect will be an increase in global pollution as mines in countries with more lax application of law and regulations controlling environmental damage replace those of Canada. Tax benefits and incentives are a more efficient means than arbitrary regulations in minimizing environmental damage."

Jan 1, 1994

By R. V. Typliski, G. J. Labarre

"Hudson Bay Mining and Smelting Co., Limited, Flin Flon, Manitoba, has developed a metallurgical wastewater treatment system employing two-stage lime neutralization, sludge recirculation and conventional mechanical thickening.Laboratory investigations, initiated in 1970, led to the construction of a pilot-scale minewater treatment plant, at Schist Lake Mine, in early 1971. This plant, treating 600 cubic metres /day of wastewater containing 30-60 mg/1 zinc. demonstrated metal extraction efficiencies of 99% under normal operating conditions.On the basis of this pilot work, a second pilot-scale treatment system was established in 1975 at the Flin Flon metallurgical plant to treat zinc refinery process waste water. Through numerous improvements, including automatic con¬trol equipment, the system has evolved to a full-scale operation capable of treating 800 cubic metres/day of wastewater containing 4-11 gm/1 zinc. Treated effluent contains 0.2-20 mg/1 zinc. The hydroxide sludge produced returns to the metallurgical process for the recovery of metals while clarified effluent discharges to waste.With the system, Hudson Bay Mining has achieved its original goal: the reduction of environmental contamination, while realizing a return from metal recovery.IntroductionWith the goal of reducing environmental contamination, Hudson Bay Mining and Smelting began laboratory testwork, during the late 1960's, into the methods and technology for neutralizing and removing heavy metals from acid mine drainage. Based on lime treatment, early tests showed much promise and culminated in the construction of a pilot-scale test plant at Schist Lake Mine in early 1971.This pilot system utilized technology developed in laboratory studies, and related to work then underway by state authorities in Pennsylvania coal mines. The basic operation consisted of a lime slurry tank, baffle reactor and a free-settling basin. Through three summers of operation, the Schist plant, capable of treating 600 cubic metres/day of minewater, produced a heavy-metal extraction of 99% under normal conditions. Although successful in proving the treatment chemistry, the plant displayed deficiencies in sludge densification and handling."

Jan 1, 1980

By K. Fumimura, T. Nishimura, M. Kohno

When applying numerical techniques to problems of deformation of rocks, the body to be analyzed is divided into small portions and is represented by a system of points linked together with the neighboring points. In the so-called distinct element modeling, the particles in the system are directly connected by springs and a contact law is used to specify forces on the particles to simulate the mechanical behavior of the body. The relation between the spring stiffness and commonly measured material properties, such as the Young’s modulus and the Poisson’s ratio, should be known a priori. For the general case of a random packing of particles, the relation is found by means of a process in which a system of particles and set of parameters are prepared to simulate a set of specimen-size test and then the input parameters are chosen to match the measured material properties. The validity of the numerical result is only demonstrated by comparison model behaviors with the measured responses. The process includes trial-and-error manner, therefore, no model is complete to reproduce the mechanical properties. In this paper, a relation between the spring stiffness and the elastic constants; the Young’s modulus and the Poisson’s ratio, is introduced to a three-dimensional distinct lattice spring method. Two simple numerical examples will be presented to demonstrate the performance of the method with the procedure for the determination of the spring stiffness.

Jan 1, 2015

"The Dome Mine, located in South Porcupine Ont. has been in operation since 1910 and is owned and operated by Placer Dome Inc. The current milling facilities were constructed in two phases with the first being commissioned in 1982. It consists of a grinding, gravity separation, thickening, and leaching circuits. The second phase was commissioned in 1988 with the addition of the CIP, stripping, electrowinning, and carbon regeneration circuits.It is now common practice in the gold processing community to add liquid oxygen to leach circuits to increase both recovery and kinetics. Along with these benefits the metallurgical group at the Dome realized the potential to replace compressed air with liquid oxygen as a source of oxygen for the dissolution of gold. A plant trial of liquid oxygen was undertaken during the fall of 1991. The results of this first test were favourable enough to warrant further investigation, and a second plant trial was conducted in December 1991.The data generated as a result of each trial revealed that oxygen could be economically substituted for compressed air as a source of dissolved 02. The energy savings in required horsepower enabled a rapid payback period. Thus the project was approved in the spring of 1992 and l should be operational during the final quarter of 1992. INTRODUCTIONIn a continuing effort to reduce operating costs and improve recovery at the Dome mill it was decided to investigate the feasibility of adding liquid oxygen (02) to the leach circuit. It is now common practice in the gold processing community to add 02 to the leaching process to increase both kinetics and recovery. It was anticipated that an increase in kinetics would allow us to eliminate one or more leach tanks while maintaining acceptable recoveries. The metallurgical group felt that along with these benefits, the potential was also there to reduce power consumption through the reduction in the processing of compressed air which is quite costly (12 cents/1000 cubic feet per minute in 1991)."

Jan 1, 1993

By Angeles Mendoza Sammet

Based on the analysis of issues associated to conflicts between communities and mining companies in Mexico, this paper suggests actions to make mining more sustainable in Mexico. Interviews with key informants and a revision of documental information available on the internet provided information on 15 cases of conflicts in various parts of the country. The issues varied from incompliance with environmental law to assassination of community members opposing mining. The analysis concludes that mining is not sustainable in Mexico. Both mining companies and the Government of Mexico can make changes to improve sustainability. Mining companies could take a proactive approach and engage in consultation with communities before starting operations. Sharing information with communities on environmental management programs and monitoring results can be a way to start building trust and demonstrate environmental commitments. Companies can implement and evaluate CSR policies to ensure that all staff and contractors are trained on them to reduce and/or prevent corruption and violations of human and indigenous rights. Only 3 of the 15 companies had clear social responsibility policies or sustainability targets, but no reports evaluating them. Complying with the law does not make a project sustainable because of corruption, deficient enforcement, and gaps in legislation. The Government of Mexico should address the following points to make mining more consistent with sustainable development. Update the mining legislation to introduce sustainable development principles and consultation. Incorporate the notion of Free, Prior, Informed Consent (FPIC) for Indigenous People (IP) on all applicable Mexican laws or regulations. The government should not grant concessions on protected areas or indigenous lands without extensive meaningful consultation with the public, IP and land owners. Finally, it is vital to increase SEMARNAT?s capacity to review impact assessment reports and inspect and monitor environmental compliance along the life cycle of projects.

Aug 1, 2013

By Colin Jones

Canadian Clay Products Inc., which mines bentonite in Saskatchewan near Truax and operates a plant at Wilcox, is the sole producer of swelling bentonite, often called western bentonite, in Canada. Seven products produced by the company are used in binders, sealants, water and waste water treatment, plasticizing agents, foundries and absorbents. Reserves are reported at about one million tonnes for the deposit but the area in general contains significant additional reserves.

Jan 1, 2001

By Michel Noël

This paper presents a partial compilation of adopted measures of waste rock dump closures at mine sites located in Canada and Alaska, where the climate includes cold winters. The paper also presents the selection process that was followed for some of those mine sites. Mining operations usually generate waste rock that can sometimes result in very large quantities. Additionally, the nature of the ore body and the host rock will often introduce environmental impacts. These impacts need to be managed not only during the operations but also in the long term. Mine closure plans consequently have to address the long term issues that sometimes require perpetual treatment. Closure planning often involves the evaluation of risks associated with environmental and financial liabilities. It needs to consider the science, some common definition of objectives, and there will be a need to manage resources and schedules. Closure planning is essentially an exercise in constrained decision making. A performance and risk based ranking matrix is often developed during this selection process to identify the preferred option(s). The case studies presented in this paper provides a few examples. The level of knowledge on acid rock drainage from waste rock dumps has increased considerably over the past decades. It did not necessarily increase the level of complexity of the adopted closure methods, as the selected closure methods are often kept simple. A common approach consists of stabilising the slopes of the waste rock dumps material by resloping and then covering the waste rock with a growth media to support vegetation. Such covers prevent direct contact of animals with the waste rock material, minimise erosion and reduce infiltration to various degrees. The inclusion of water treatment is obviously dependent on the water quality being released.

Nov 1, 2008

By O. Guyot, A. Broussaud, M. Revalor, G. Legrand, D. Kok, E. Roux

"The paper describes the advanced grinding control system implemented at Newmont Ahafo gold mine, Ghana in 2009 and 2010. It shows how the different components of the Advanced Process Control (APC) system cooperate for increasing plant performance.The SABC circuit processes hard rock from different pits mixed with a variable proportion of oxides. The control strategy is designed to address specific disturbances, including start/stops of pebble crushers, unavailability of oxides, changes in rock size distribution resulting from segregation in the stockpile, and changes in ore type and hardness.The system consists of an expert system per se with extensive use of fuzzy logic, supplemented by an online dynamic model of the process used as a soft sensor, a VisioRock™ rock size measurement system over SAG mill feed before addition of recycled pebbles, and an AudioMill™ system to analyze the SAG mill sound and detect impacts on liners. All these components are embedded in the same OCS© software platform, which, among other benefits, makes it easy to support the entire system remotely. The paper details the physical constraints and the variables that are manipulated. It describes the control strategy and the contribution of each component of the system. It also describes the project implementation and the performance of the system. In addition to a strong involvement and support of management, the very good acceptance of the operators has been facilitated by the remote access system that made it possible to immediately modify the system each time it was needed during the baby sitting phase.The system made it possible to increase gold production significantly through increases in tonnage and recovery thanks to a better control of the grind size through a stabilization of the secondary ball milling circuit and an improvement of the operating conditions of the classifying cyclones."

Jan 1, 2012

By I. J. Burgess, B. C. Barlow

"The electrodissolution of nickel pellets with different controlled electrical variables was investigated in an effort to mitigate plating residue in Watts bath based electroplating cells. During galvanostatic dissolution at 0.4 A dm-2, the anode potential was seen to oscillate between passive and pitting potentials. In-situ microscopy and ex-situ characterization has shown that lacy-pit formation and large, partially perforated, pit covers form during the potential decay from pitting potentials. In general, covered pitting at low current density shows increased plating residue. Using potential pulses is one way to maintain greater control over surface pitting by creating a higher density of pit nuclei while at the same time controlling their growth. Pits generated from a series potential pulses were examined ex situ for a range of pulse times and stages of pit growth were identified. An alternative method of anode dissolution was devised using potential pulses and duty cycles that allowed average current densities comparable to industrial plating conditions to be achieved. By restricting the time at pitting potentials to 0.05 s, plating residue was reduced more than six-fold in comparison to an equivalent galvanostatic experiment run at a comparable current density.INTRODUCTIONIn typical galvanostatic (direct current) nickel electroplating cells employing soluble anodes, some amount of plating residue is produced which consists of metallic nickel and impurities that detach from the bulk in the form of small fines. Significant buildup of residue requires plating operations be halted and the anode assembly cleaned of residue before operation can resume. While variables in the refining process have been shown to affect plating residue, more precise control of electrochemical variables may provide an attractive route to mitigation of residue."

Jan 1, 2016

By Gabriel Voicu, Marc Bardoux, Ross Stevenson, Nuno Machado, Jean Lafrance

"Abstract - Paleoproterozoic gold is found in two different volcano-sedimentary sequences and intrusive bodies separated by 600 km within the Guiana Shield. The 2148 Ma St-Élie granite intruded volcanic-arc sequences of the Paramaca Group, whereas the 2096 Ma Omai stock penetrated backarc/ island-arc sequences of the Barama-Mazaruni Group. Positive ?Nd values suggest that both suites lack Archean crustal contaminants, which is consistent with an origin in an oceanic arc setting.The St-Élie deposit is characterized by quartz-dominant vein systems with minor metallic minerals, represented chiefly by pyrrhotite and pyrite. Biotite, calcite, and chlorite are the main gangue minerals. The alteration haloes at St-Élie feature a strong potassic zone, which is absent at Omai. The ore-controlling structures are ductile and the vein emplacement is related mainly to contemporaneous, high-angle ductile shear zones. The St-Élie deposit formed at temperatures >350°C. The stable isotopes values are compatible with a magmatic or metamorphic source.The Omai deposit is characterized by quartz-dominant vein systems with minor metallic minerals, represented mainly by pyrite. Ankerite, scheelite, albite, and chlorite are common gangue minerals. The vein emplacement is syn- to post-deformation and it is related mainly to brittle shear zones with low-angle, stockwork networks and breccia zones. The Omai deposit formed in a temperature range between 250°C and 170°C, much lower than the St-Élie deposit. The stable isotope values are compatible with mixing between deep-seated fluids of metamorphic or magmatic origin with surface- derived fluids.These differences between St-Élie and Omai are interpreted in terms of their depth of formation. Alteration patterns, structural elements, and paragenetic assemblages indicate that the gold at St-Élie was most probably emplaced at a mesozonal depth, whereas the Omai setting yields evidence for epizonal conditions."

Jan 1, 1999

By Rodnei Graça, Jorge Silva Bettencourt, Lena Virgínia Soares Monteiro, Baruch Spiro, Tolentino Flávio De Oliveira

Abstract - The Vazante Mine is located in the Vazante District, the largest zinc district in Brazil. The Vazante deposit consists dominantly of an unusual willemitic ore. Small sulfide bodies are tectonically imbricated with the willemitic ore, within the Vazante shear zone. Structural styles of deformation and petrographic and isotopic evidence indicate that willemitic mineralization and deformation occurred synchronously during the Neo-Proterozoic. Various generations of hydrothermal veins and hydraulic breccias may pre-date, accompany and overprint the mineralization. Ore-formation temperatures are deduced from stable isotope geothermometry and mineral chemistry of both sulfide bodies and willemitic ore. Temperatures during the main stage of mineralization range from 206°C to 294°C (willemitic ore) and 317°C (sulfides), and reflect the prevailing metamorphic conditions within the shear zone. The fluid from which the gangue minerals of the sulfide bodies precipitated (at 250°C) had an oxygen isotopic average value of ?18O = +19.4‰. This value appears to reflect the interaction of metamorphic fluid with the carbonate rocks of the Vazante formation. At 250°C, the fluid in equilibrium with the vein mineral phases and willemitic ore assemblage exhibits a uniform oxygen isotopic composition, with an average value of ?18O = +11.5‰. The positive linear covariance of ?18O and ?13C ratios of the carbonates is most likely due to the mixing of metamorphic and meteoric fluids. The ?34S values of sulfides indicate a direct crustal origin for the sulfur. It is suggested that the sulfur is largely derived from pre-existing sulfide bodies and has been transported by metamorphic fluids. The willemitic ore may have originated from the precipitation of metal in sulfur- poor fluids under oxidized conditions, within the Vazante shear zone.

Jan 1, 1999

By L. Lamothe, C. H. The

"Pilot precipitator tests were conducted at Noranda's Horne Smelter in late 1978 to evaluate methods of improving converter dust collection efficiency. A bout 35 Nms/min. of converter off-gas were isokineticatly diverted from the converter flue to the pilot precipitator leased from Flakt (Canada) Ltd., consisting of three fields, one transformer-rectifier set per field and 77-m2 total collecting plate area. The effects of gas volume flow rate and conditioning the gas with sulphur trioxide and/or additional moisture were tested. II was found that gas flow rate and moisture level had the most pronounced effect on collection efficiency. Based on a techno-economic assessment of different options for improving converter Courell efficiency, waffle hoods and water sprays were installed on the converters to reduce air infiltration and increase the moisture level in the gas.BackgroundThe Horne Smelter of Noranda Inc. is situated in northwestern Quebec and, since the closure o f the min e in 1976, has been operating as a custom smelter. The concentrates treated at the smelter come from various mines with mixed sulphide ores , many o f them containing significant amounts of lead and zinc which makes dust collection in electrostatic precipitators mo re difficult than normal.As part of a continuing program on reducing smelter dust emissions, the No . 6 Cottrell was installed in 1972 up stream of Nos. 2 and 4 Cottrells (in parallel) in a n attempt to improve dust collection by increasing the over- all precipitator capacity ( Fig. I). However, it has never per formed a t its designed efficiency o f 94%. The average efficiency established in various test s was in the range of 60 – 65%."

Jan 1, 1985

By G. J. Kipouros, P. W. Kingston, W. F. Caley

"Current practice in advanced materials processing has involved the dispersion of a second-phase, commonly SiC, glass, or other non-metallic fibres/whiskers/particulates to enhance physical characteristics of the matrix. These matrices may be either ceramic or metallic but in either case it is important that the physical and chemical properties of each phase be compatible. The dispersed, finely divided second phase is often both expensive and foreign-produced and may exhibit chemical instability at elevated temperatures. Thus, it would appear that certain naturally-occurring industrial mineral fibres/whiskers/particulates might offer an attractive and low-cost alternative. Suitable candidates, such as wollastonite and sillimanite, are available in Canada and may be milled to produce particles whose shape is appropriate for this application. It is suggested that wollastonite, in particular, may be a useful modifying agent in metal matrix composites utilizing AI, Al-Si, Zn-Al or other light metals and alloys. In addition, the possible use of these minerals in ceramic matrix materials is also addressed, with reference to a preliminary thermodynamic analysis of the systems involved.IntroductionBackgroundA composite material may be thought of as consisting of a matrix component, the properties of which are improved by the addition of a second component or dispersed phase which forms a distinct three-dimensional interface with the matrix. This matrix is commonly either metallic or ceramic, which leads to the two most popular types of composites: metal-matrix composites (MMC); and ceramic-matrix composites (CMC).Such materials are by no means new. Early composites include fiberglass, mixtures of plaster and horsehair in wall plastering, as well as use of natural materials such as bamboo in fishing rods. Some of the newer applications include high strength, low-weight bicycle rims, as well as the more familiar role in aircraft and automobile engine components."

Jan 1, 1993

By J. R. Shouldice

"IntroductionREEFS of Silurian age are recognized in southwestern Ontario, both in outcrop and from subsurface information. This paper deals with the so-called 'pinnacle' reefs which are known only in the subsurface. For the purpose of this paper, the pinnacle reefs are arbitrarily defined as those structures having a height of over 250 feet and a length of less than two miles. This definition eliminates numerous mounds and other broader, more subdued, structures of less certain origin, found in subsurface beds.The term 'pinnacle reef' is perhaps unfortunate, but it is in common usage in Ontario and is used elsewhere for different types of reefs. A new name is justified by the unusual environment and structure of the Ontario reefs, but it is unlikely that any other term would gain acceptance. Rather than propose a new term which would be ignored or result in further confusion and misuse, the name 'pinnacle', as defined above, is used in this paper.Pinnacle reefs have been found over a fairly large part of southwestern Ontario. The known reefs of this type parallel the southeast edge of lake Huron and •follow the strike of the structure contours which circle the Michigan basin (see Figure 1). In total, twenty-five such reefs have been discovered in southwestern Ontario."

Jan 1, 1955

By Y. Hanada

Electrorefining at higher current density is desirable due to the increase in productivity attained without expanding the plant size. However, increasing the current density in common commercial practice causes problems such as anode passivation, dendritic deposition, cathode impurities and energy consumption. In general, agitation of the electrolyte is effective in suppressing these problems. To apply the agitation to commercial practice effectively, the method of agitation is important. One possible method is agitation by gas injection. In this study, fluid motion characteristics with gas injection between electrodes were investigated using a water model. Flow patterns were observed and fluid velocity was measured using a particle tracking method. It was found that the time-averaged velocity near the electrode walls was of the order of 0.1 m/s in the conditions. The flow was highly turbulent. The turbulent component of velocity was the same order as the time-averaged velocity. The mass transfer coefficient between the wall and fluid doubled when the effect of turbulent intensity was taken into account. The effects of gas injection on the electrolysis behaviour at high current density were discussed in terms of the mass transfer. It is suggested that gas injection could suppress the problems at high current density.

Jan 1, 2007