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By Alan E. Gallie

FOR many years the Witwatersrand has been the leading gold mining r camp in the world and, to a Canadian mining student, could not fail to be of overwhelming interest. The vast scale upon which the operations are conducted, the enormous production accomplished, and the perfection of the operative technique, have all so forcibly impressed themselves on his memory that it is difficult to select any one feature as more outstanding than another. For the purposes of this paper, however, the author has selected the very first feature of mine operation with which he came in contact, namely, shaft sinking, as it reflects, quite as well as any other, the spirit of mining in South Africa. Early mining in Johannesburg was by open cuts or trenches, dug along the outcrops of the reefs. The ore was thrown from bench to bench to the surface. As the depth increased, rock was hoisted by bullocks. In 1887, the first shafts were sunk and true underground work began. At the same time, boreholes were put down to test the continuity of the reefs at depth. The first was at the Village Main reef. It cut the South reef at 517 feet and the Main reef leader at 581 feet. The Main reef leader assayed eleven penny-weights. Subsequent boreholes proved the reefs down to thousands of feet. Many companies secured deep-level claims as a direct result of the information obtained from the early holes. These companies then held land on which there was no readily available ore. In order to get to their pay rock, vertical shafts through the upper strata were necessary. Shareholders were impatient, and shafts had to be sunk as speedily as possible. The old methods of shaft sinking were investigated, new methods developed, and soon all records were being broken. In the last thirty-five years, the record has been slowly advanced, and last summer it was again broken to stand at 430 feet in a 31-day month. During the period from 1915 to 1935 inclusive, in the Witwatersrand district, 96 miles of shafts were sunk. Today, with the advance in the price of gold and the increase in the mining area, there are over twenty-five major shaft-sinking operations being carried on.

Jan 1, 1937

By E. S. Moore

GOLD was discovered previous to the year 1900 on the east shore of Emerald lake, Afton township, Timagami Forest Reserve. It was found in a small cavern in banded iron formation, close to the water's edge. This occurrence of gold was mentioned in several reports that referred briefly to this area, and prospectors evinced considerable interest in the region. It was not, however, until the Golden Rose Mining Company, which was incorporated in 1909, started operations that much work was done on the property. In 1915-16, this Company, under the direction of E. J. Townsend, the President, did a considerable amount of work. A small mill was built and ore was extracted from pits, trenches, and a one~ hundred-foot shaft. In 1927, Afton Mines, Limited, was incorporated to take over the property, and about thirty men were employed for a time. During 1934, the New Golden Rose Mining Company was organized to handle the property, and the Consolidated Mining and Smelting Company of Canada, Limited, undertook to develop the mine. In March of the following year, this Company began deepening the shaft from 100 feet to 500 feet. A considerable amount of drilling had previously been done on the hill of iron formation in which the mine is located. Further drilling was done from the surface, and altogether about twelve holes have been put down to test the formations. Over 2,000 feet of drilling has also been done from the underground workings. The mine is now known officially as the New Golden Rose mine, although to many it is better known as the Afton. To reach the property during the summer months, there is a boat trip of about thirty miles from Timagami, a wagon-road portage of one mile to Obabika lake, a boat trip of ten miles on this lake, and finally a wagon-road portage of one and one-quarter miles to Emerald lake. The mine lies about three-quarters of a mile down the east shore of the lake. A 75 h.p. Diesel engine and compressor were taken in over this' route last summer, and it is evident that the transportation problem is quite a serious one. Airplanes have been much in use, and a winter road runs from the mine to Chudleigh, on the .Canadian National railway near Sudbury.

Jan 1, 1936

By Ahmad Ghahreman, Lin Li

"In this study, the Fe(II)/Fe(III) redox reaction kinetics on the surface of pyrite, have been investigated in a 0.5 mol L-1 sulfuric acid solution for a temperature range of 22 to 65°C. Based on mixed potential theory, chronoamperometry is introduced to study the Fe(II)/Fe(III) kinetics by subtracting the current density of pyrite oxidation in an iron-free acidic solution from that in an iron-containing solution at the same applied polarized potential. Tafel behavior was established by this method to analyze the kinetics of the Fe(II)/Fe(III) redox reactions. The results showed that exchange current densities increased slightly with temperature, however remained on the order of 10-5 A cm-2. The activation energy for Fe(II) oxidation and Fe(III) reduction on the pyrite surfaces was calculated to be 102.0 and 32.7 kJ mol-1, respectively. Anodic transfer coefficients also increased, from 0.24 to 0.39, with increasing temperature, which indicates a weakened n-type semiconductor property at higher temperatures. Electrochemical impedance spectroscopy measurements have indicated that at lower anodic over potentials the charge transfer is the rate determining step of pyrite oxidative dissolution in sulfuric acid solution. In the presence of Fe ions, the major contribution of the total current density comes from the Fe(II)/Fe(III) redox reaction. INTRODUCTION Pyrite, an abundant sulfides mineral in the nature, is commonly considered a valueless gangue mineral frequently associated with other valuable sulfide minerals such as chalcopyrite, or metals such as gold, or coal (Lin & Say, 1999). Pyrite oxidation has been the subject of extensive research in view of gold metallurgy, as oxidation of pyrite is the initial step to break down the pyrite lattice and expose the encapsulated fine gold particles (Gasparrini, 1983). Fe(III) ion and dissolved oxygen (DO) have generally been considered as the two most important oxidants with respect to pyrite oxidation, having been studied extensively in previous research (Zheng, Allen, & Bautista, 1986; King Jr & Lewis, 1980). The process of pyrite oxidation can be viewed as a series of reactions amongst pyrite, ferrous, ferric and oxygen in which pyrite is initially oxidized by the dissolved oxygen in water forming ferrous (Eq. 1), and then the ferrous also is oxidized by he dissolved oxygen to form ferric (Eq. 2). The ferric, produced by reaction 2, then could potentially oxidize pyrite (Eq. 3) and convert to ferrous."

Jan 1, 2017

By Brian Hart, Zhe Chen, Liuyin Xia, Mana Pourdasht, Stamen Dimov

"Gold losses related to carbonaceous matter (CM) during processing are a significant problem in the gold processing industry. Inherent CM in gold ores can behave similarly to activated carbon in its ability to adsorb gold cyanide. This phenomenon is termed preg-robbing as the surface adsorbed gold cannot, for the most part, be recovered. Research has identified that gold adsorption by inherent CM is linked to the specific surface area, pore structure, degree of C disorder and surface functional groups. One of the strategies to inhibit CM preg-robbing prior to leaching is a chemical oxidation; a process linked to modification of the surface functionality. In this study, the variability in gold cyanide adsorption due to oxidation with different reagents has been investigated. Variability in gold cyanide adsorption by CM is examined in relation to structural and surface modifications using TOF-SIMS, XPS and Raman spectroscopy.INTRODUCTION A major obstacle for effective gold recovery during carbon in leach (CIL) or carbon in pulp (CIP) processes carbonaceous gold ores is the presence of carbonaceous matter (c-matter) which has the ability to adsorb, or preg-rob gold from the cyanide leach solution. It can be responsible for poor recoveries as the carbonaceous materials (CMs) within the ore competes with activated carbon used during the leaching and adsorption phase of processing (Cay, 2014). Preg-robbing capacity can vary significantly with mild preg-robbing ores showing absorption capacities of less than 1 g Au/t ore, while severe preg-robbing ores may have CM with the capacity to preg-rob more than 500 g Au/t ore (Dunne, 2007). Research by a number of groups have shown that the degree of C disorder has some influence on the ability of the carbonaceous material to adsorb Au(CN)2- (Miller et al, 2005, Helm et al, 2009, Hart et al, 2010). It is also apparent the adsorption characteristics of carbonaceous material is affected by changes in surface chemistry (Dimov, 2016). Various treatment including; flotation to remove the carbonaceous material (Wills, 2010), addition of surface blinding agents (for example kerosene) to passivate or blanket the carbon surfaces (Dimov, 2016), addition of strong adsorbents (eg. activated carbon or resin) to compete with the carbonaceous material and passivation or surface coating by oxidation (pressure, roasting, chlorination and biological oxidation), have been employed prior to leaching in an attempt to minimize the gold losses (Dunne, 2013)."

Jan 1, 2017

By Ali Montaser

Hauling trucks are important part of equipment fleets for large earthmoving operations such as those encountered in dams and highway construction projects. This paper presents an automated methodology for tracking and estimating productivity of hauling trucks fleet operations in near-real-time. Recent advancement in automated site data acquisition technologies made their use in tracking and monitoring of construction operations feasible. However, these technologies fail to track hauling truck fleets due to the change in the cut and fill locations from one cycle to another; making tracking and progress reporting difficult and inaccurate. In addition, there is very little work done utilizing data sensed directly from equipment, for example sensing when truck dumping bed is raised during the dumping process. The technologies deployed in the developed method are Radio Frequency Identification (RFID) and equipment control sensors. Low cost passive RFID tags are attached to hauling trucks and fixed RFID readers are attached to loaders or excavators. The read range of the used RFID tag is centimeters, to be activated only when a loader with an attached RFID reader is loading a truck. On the other hand, control sensor is connected to the truck control system and operated by the motion of its movable bed. The function of control sensors is to record the signal time when the truck operator gives order to the truck control system to raise or lower truck bed. The captured data is then transferred wirelessly from the RFID reader and control sensor to a computer housed in one of the temporary offices onsite and subsequently to the main server in the contractor?s head office. Fusing the data captured from RFID reader and control sensor is used to identify loading, travel, dumping and return time that constitute the hauling truck cycle time. The collected data is analyzed and processed automatically, without human intervention, to calculate the productivity of the hauling truck and to report it directly to onsite personnel. Relational database is developed to support the implementation of the proposed method. The developed database is used to process the data captured by the RFID and the control sensor to calculate the productivity achieved in cutfill operations in near-real-time. The developed methodology is expected to facilitate early detection of discrepancies between actual and planned performances.

Aug 1, 2013

By S. D. Anitha Kumari, T. G. Sitharam

"The huge urbanisation of the world cities have invariably resulted in enormous requirements of development in transport and other facilities. As the surface space available for the construction of these infrastructural facilities is found to be inadequate, underground space is widely used recently for this purpose. However, to understand the behaviour of these underground structures through experiments under various loading conditions is not practically feasible. Hence numerical methods have widely been used to model these structures and predict their behaviour. The underground structures generally rest on soil or rock. Depending upon the properties of the material surrounding the tunnel, the deformation pattern and the stress contours vary. If the tunnels are placed on soft ground at a shallow depth, the presence of existing structures will add to the stresses and strains developed. In the case of densely populated cities, tunnelling operation may result in huge damages if the settlements are not within the desirable limits. This may in turn lead to the collapse of the tunnel along with adjoining structures. So the determination of stress levels associated with the yield of wall due to excavation is very important and necessary supports and reinforcement should be provided. Numerical simulations using discrete element method (DEM) and finite element method (FEM) have been done to understand the stress variation around single and twin tunnels. Studies are also done to quantify the improvement of stability on the introduction of lining around the tunnels in a weak cemented soil mass like sandstone.INTRODUCTIONMost of the life line facilities which include pipelines for electricity, water, communication, sewage, gas, roads, metro, utility tunnels etc in modern urban areas are underground structures. Infrastructure development is crucial for any city and sustainable development urges for underground constructions. Accordingly, there is already a great demand for tunnels to be constructed in difficult and crowded urban settings. This results in the fact that a large number of risk factors are associated with tunnels in these densely populated urban areas. These constraints pose threats to tunnel construction and also demands for minimal disturbance to the public and to the surrounding utilities. One of the most important factor to be considered while designing an underground structure is its stability with respect to the surrounding medium and adjoining existing structures. In this study, a comprehensive presentation of the numerical modeling of single and twin tunnels adopting two different methods is presented."

Jan 1, 2015

By R. Clarkson

"Free gold particles occur in many base metal and precious metal mines throughout the world. Due to the high density and malleability of gold, large circulating loads of free gold particles can build up over time in grinding circuits. This gold is often deposited in unintended traps throughout the mineral processing system.These unidentified free gold deposits represent a serious security risk as well as an inaccessible inventory of gold. Deposits of free gold particles often remain undetected by mine management until they are accidentally discovered while repairing mill equipment.Nuclear tracers have been used to determine the free gold recovery efficiency of gravity recovery equipment, drills, and sampling equipment (Clarkson, 1994, 1995; Walsh and Rao, 1986; Walsh and Kelly, 1992). In November, 1993, the author inspected the grinding circuit at La Mine Doyon in Rouyn-Noranda, Quebec and made recommendations to recover coarse gold and to eliminate gold traps from the circuit. In 1995, the author salted mineral processing circuits with radioactive gold particles. The gamma and X-ray radiation from gold’s nuclear isotope (Au198) were detected through steel, in pipes, and in moving equipment using scintillometers. The radiotracers proved to be a safe, rapid and accurate method of identifying gold traps and improving security.Nuclear TracersWhen particles of gold are placed in a nuclear reactor, some of the gold atoms (Au197) absorb another neutron in their nucleus to form gold’s radioactive isotope (Au198). In the process of radioactive decay, this isotope emits high energy gamma rays and X-rays which are easily detected (even through steel) with scintillometers.Radioactive gold (Au198) has a very short halflife of 2.7 days. At the relatively low activity levels used for tracing, the particles remain detectable with a small hand-held scintillometer for about 10 to 14 days. After 14 days the irradiated gold is close to background levels and within two months it is essentially non-radioactive. The radiation has no effect on the recovery characteristics of the gold particles. The gold radiotracers are very safe due to their very low level of radiation, short half-life, and their inherent physical and chemical stability. However, the use and possession of even mildly irradiated gold is strictly licensed and regulated."

Jan 1, 1997

By Hans Lundberg

The magnetometer which was developed during the war for detecting submarines has proven exceedingly valuable in outlining deep-seated structures in oil exploration, and will be useful also to geologists in outlining regional structural features in the Precambrian. Our magnetometer has been developed to outline local and detail structures. 1 am quite sure that all geophysicists and geologists would agree with me that, in ore prospecting, it is important to obtain as much detailed information as possible. We know that, as we ascend from the ground and get away from the magnetic ore-bearing structures and orebodies, the magnetic intensity decreases rapidly, but, worse than that, we lose the details even faster. Figure l shows two strong, very sharp, magnetic 'highs' over two orebodies which, as our distance increases, rapidly merge into one fairly broad, moderately strong anomaly. If we drilled on this maximum, we would not encounter any of the orebodies. Therefore, we should fly the airborne magnetometer as close to the ground as possible in order to duplicate the results of the magnetic ground surveys. The first chance to accomplish this came with the helicopter, which is an exceedingly maneuverable aircraft. It can be landed in a cleared space not much more than fifty feet square. With floats, it can be landed anywhere, even in a swamp, on thin ice, or on soft snow. It can stand still in the air, hovering over a given point. It can ascend and descend vertically, fly sideways and even backwards, at the will of the pilot. It flies forward at any speed up to l00 miles an hour. The helicopter can be taken to any desired position at a given time. It can fly at any useful altitude from a few feet to several thousand feet above the ground. It can fly very close to the ground with safety. In bare areas, the survey flight may be performed a few feet above the ground. In forested areas, however, the flights, to clear the trees, must be made at l00 to 150 feet. To mark out a certain point, a small parachute-like marker may be draped over a tree or laid on the ground. This can be done from the helicopter without touching the ground.

Jan 1, 1947

By R. D. Livingstone

"THE LETHBRIDGE COAL FIELD lies mainly .to the north and west of the city of Lethbridge. Mining carried on in this area for over eighty years until 1965. Before the building of a railway the coal was carried by bullock wagon to Montana for use in smelting, and for a while by river boat to Medicine Hat for railway use. The single, almost flat, worked seam is designated the ""Galt"" seam and is about 1.5 metres thick. It belongs to the Belly River formation and is under cover of 80 to 180 metres of weakly stratified sediments. A complex system of cross faults adds to the mining difficulties. Close timbering required in the entries and rooms reflected in a high timber cost and lower output per man shift. The coal is High Volatile"" C"" bituminous in rank with maximum gross calorific value of 11,200 Btu per pound and with a well defined cleavage. Roof conditions in the field range from very tender and very heavy on the south end of the field and west of the Oldman River to a more stable character to the north. Relatively speaking, the whole field would earn a rather tender rating and definitely so in relation to many U.S. fields. Floor conditions are characterized by a bentonitic type heaving in the south end of the field west of the Oldman river to a more stable situation in the north, which can tolerate shuttle car operation if kept drained. Water problems are minimal, except paralleling the Oldman River, where the seam dips below the river level. While vigilance is necessary to prevent accumulations of gas, the volume is rather limited. The seam was entered by shafts, except where small mines were located along the Oldman river banks and gained access by drifts. The coal seam was developed by driving either 3 or 4 Face entries 2 1/2 metres (8 ft) wide on 18-metre ( 60-ft) centres. Sets of dual butt entries driven at right angles to the Face entries completed development work. Normally rooms up to 8 metres wide were turned off the butt entries on up to 11 - metre centres. These were worked in groups of three to five, depending on the roof conditions, and normally advanced 60 m (200 ft). In some areas rooms had to be abandoned short of their objectives due to roof pressure, heaving floor and intermittent work."

Jan 1, 1985

By D. W. Heard

Electrospark Deposition (ESD) is a low heat-input, high energy density, micro-welding process. The short pulse duration and high-pulse frequency, in combination with the small amount of material transferred during each pulse, results in the evolution of extremely rapid cooling rates, believed to approach 105-106 °C/s [1]. This rapid solidification event results in the refinement of the microstructure to the nanostructured or amorphous level [2, 3]. Figure 1 displays the resultant microstructure of an Al-17%Si alloy deposited by the ESD process. Furthermore, it was determined that the microstructure of the deposit remained unchanged after subsequent layers were welded onto the presented layer. Freeforming of materials is a rapid prototyping process in which the deposited feedstock is built-up to the desired geometry in a near-net shape manner. Figure 2 displays the automated set-up employed produce three dimensional freeformed objects via multiple deposition trials of the ESD process. The automated XYZ table is equipped with CNC software to transform CAD renderings into three dimensional tool paths. Figure 3 displays an Al-12Si freeformed gear (2" diameter, 12 teeth) produced by the ESD process, prior to removal from the substrate. An SEM analysis of the freeformed component showed that the microstructure did not coarsen during the deposition of subsequent layers during the freeforming process, as depicted in Figure 4, resulting in the production of a bulk nanostructured component. This paper represents a summary of the capabilities of ESD to fabricate advanced materials possessing refined microstructure. In particular, results on the microstructural evolution obtainable for various wear-related systems will be presented. In addition, the feasibility of using the ESD process to freeform three-dimensional objects via multiple deposition passes will be presented and accompanied by a characterization of the properties of the freeformed component. [1] R. N. Johnson, "ElectroSpark Deposition: Principles and Applications," in Society of Vacuum Coaters, 2002, pp. 87-92. [2] J. Milligan, D. W. Heard, and M. Brochu, "Formation of nanostructured weldments in the Al-Si system using electrospark welding," Applied Surface Science, vol. 256, pp. 4009-4016. [3] S. Cadney and M. Brochu, "Formation of amorphous Zr41.2Ti13.8NilOCul2.5Be22.5 coatings via the ElectroSpark Deposition process," Intermetallics, vol. 16, pp. 518-523, 2008.

Jan 1, 2010

By W. H. Gauvin, N. J. Themelis

I N ADDITION to its practical importance in the beneficiation of iron ores and in direct-iron processes, the study of the reduction of iron oxides involves many aspects of challenging theoretical interest. The complexity of the reduction process combined with the fact that under different experimental conditions the controlling stage for the reaction may not necessarily be the same, has led experimenters in this field to a wide diversity of opinion regarding the reaction mecl1anism. As a rule, each investigation has been restricted to the study of one or two variables over a comparative]~• narrow range of experimental conditions, and consequently, it be-comes necessary to examine the significance of each published work in the light of the results of other experimenters in the field.

Jan 1, 1962

By J. S. Kirkaldy, W. J. Slater, G. R. Mason

Activation analysis for copper and manganese in 10 mg samples machined from aluminum-base diffusion couples has been used in the study of ternary diffusion in the Al-Cu-Mn system. The accuracy, economy and convenience of the method are considered to be very competitive with other methods for analysis of such small samples. Neutron-activated aluminum-zinc alloys in the range from 10 per cent to 100 per cent zinc have been equilibrated with a known volume and the vapors subsequently condensed and collected. The vapor pressures relative to pure zinc (the thermodynamic activities) have been determined at 550°C' by recording the relative count of /'-rays from zn65 in the collected samples. The method is a sensitive one, although subject to serious obstacles to experimental accuracy.

Jan 1, 1961

By W. A. MacWilliams, R. G. Reynolds

"This paper describes, for the first time, a patented method of extracting sodium sulphate from a natural deposit in Western Canada. The method resembles, but is not, strictly speaking, solution mining. The fact that a plant based on this method has been in successful operation since late 1969 will be of added interest. The deposit in question is located near Metiskow, Alberta, and conventional surface recovery methods could not be applied because of heavy concentrations of mud. Considerable pilot work went into the separation and recovery process on which the plant operation is based. The history of the industry is covered briefly as background to this development. Today it is clear that the method has broader application within the industry and, in concept, may generate interest in many other applications."

Jan 1, 1973

By M. Aushouri, S. H. Mansouri, N. Aminizadeh

A thermo-chemical model of the Peirce-Smith copper converter in blowing the copper stage has been developed to predict the molten temperature. The key assumption of the model was that white metal and gas phases in the converter were in thermal and chemical equilibrium. In this model, the chemical reaction of white metal and oxygen was accomplished completely. So long as sulfur existed in the bath, the generation of Cu2O was frozen. The reaction rate was considered to be constant and controlled by the reacted sulfur. The converter temperature was calculated by heat balances over time. The model was validated by a detailed comparison with measured industrial data. A good agreement was obtained. The converter temperature depended on process parameters such as oxygen efficiency, molten emissivity and oxygen enrichment.

Jan 1, 2007

By P. Gautier

Current feedstock in the aluminum hot forging processes can be used in the cast or extruded forms. The microstructural variation between as-cast and extruded materials could result in different mechanical properties and corrosion resistance for hot-forged products. Corrosion performances were examined for forged parts produced by two AA6082 feedstocks at different conditions using the following corrosion tests: open circuit potential, anodic polarization, salt spray exposure and corrosion fatigue. With the help of optical and scanning electron microscopes, metallographical investigations were carried out on cast-forged and extruded-forged materials before and after corrosion. The corrosion behavior of both materials was compared in both as-forged and aged tempers. Results show that there is no significant difference in the corrosion performance for final cast-forged and extruded-forged products.

Jan 1, 2011

By S. Duvah Pentiah

The transformation of an open pit coal mine to a horizontal-punch underground mine is subject to a number of challenges. These include scheduling the operation of various sizes of trucks over a long period, as well as updating delivery routes and dump site locations as the mine transformation progresses. In this process, rock is excavated from a quarry through earthworks. The bulk earthwork and quarry material delivery were initially drawn from traditional planning and experienced issues in their early phases. As a result, a traffic simulator was developed in order to validate schedules and predict achievable throughput, likely delays or blockages in the long term. The dynamic traffic simulator was also used to provide traffic density and vehicle arrival data at selected intersections in order to identify possible safety and efficiency issues.

Aug 1, 2013

By E. Demedde

Carbon anodes in aluminium reduction cells are continuously consumed during electrolysis. In prebake cells the anodes are replaced at regular intervals. The spent anodes, called butts, are often allowed to cool in air while emitting fluorides into the building from the hot alumina cover and the adhering bath. In modem smelters spent anodes are placed inside enclosures and fluoride emissions during cooling are effectively reduced. Fluoride emissions from spent anodes were estimated by considering the kinetics of fluoride formation, a heat transfer analysis of the cooling anode butt and the ventilation flow from a cavity. Fluoride emissions from large anode butts cooling inside enclosures were compared with those cooling in air. Good agreement with published experimental values was obtained for enclosures having different leakage opemngs, when a hydrofluorination reaction of the spent anodes was included.

Jan 1, 2006

By James L. Parks, David M. Kjos

"Designs, installation procedures and performance characteristics of martensitic cast steel concaves are reviewed. Longer wear life, fewer pieces to install and eliminating the need to scarf joints are the principal benefits of using martensitic steel to replace austenitic12% Mn (Hadfield's) steel, the traditional concave material for large gyratory crushers. Installation procedures that reduce the risk of breakage are described. Operating practices that affect concave performance are also discussed.IntroductionThe crushing machine considered to be the forerunner of the modem gyratory crusher was patented in 1878 by Charles M. Brown of the Gates Iron Works(1). The earliest gyratory crushers with receiving openings of 6 to 12 inches were fed by hand, and the crushing capacity of a mine was increased simply by installing more small crushers. The introduction of the steam shovel to open pit mining around the tum of the century provided an incentive for much larger primary crushers, and gyratory crushers with a 48 in. receiving opening were being built by 1910, followed not long afterward by machines with 54 in. and 60 in. openings to . Fortunately for the crusher maintenance people of that era, an austenitic 12% Mn steel with exceptional toughness was already available, having been discovered by Robert Abbot Hadfieldoi in 1882. Although small gyratory crushers working soft- to medium-hard rock reportedly used chilled cast iron (white iron) wear parts, these newer and much larger machines were fitted with ""Hadfield's manganese steel"" concaves and mantles to withstand the impact associated with handling large rocks .M E International first challenged the long-standing convention of using 12% Mn steel concaves in large gyratory crushers in the late 1960s when they supplied upper row concaves in martensitic cast steel for a 60-109 primary crusher at a taconite plant on the Iron Range. Since then, martensitic steels have been successfully substituted for 12010 Mn steel in concaves for more than seventy primary gyratory crushers processing iron, copper and precious metals ores, industrial minerals and crushed stone.This paper reviews materials, designs and performance characteristics of martensitic steel concaves in large gyratory crushers. The principal benefits include significantly longer wear life, fewer pieces to install and the elimination of scarfing. Obtaining the full measure of these benefits and minimizing the risk of breakage is strongly dependent on installation procedures, which are described in some detail. Operating practices that can affect performance are also discussed."

Jan 1, 1993

By F. Flynn, P. Downey, G. Ritson

"Bell Creek Mill which has been in continuous operation since 1987 has undergone numerous operational changes in the past three years. The addition of over 2. 5 million tons of resource at over 13 git from Hoyle Pond Mine precipitated an expansion program for the Bell Creek Mill. This paper discusses the major changes that have occurred over the past two years to increase throughput and efficiencies. In addition, the refractory ore treatment options are also discussed.IntroductionThe Bell Creek Mill is located in the Timmins Goldcamp approximately 8km NE of porcupine Ontario. (Fig I.)The mill was originally constructed by Camamax in 1987 to treat the Bell Creek ore at a design throughput of 350tpd. The flowsheet (Fig 2.) consisted of two stage crushing, grinding, thickening, leach and drum filtration with gold recovery by Merrill Crowe.As ore depleted at Bell Creek, the Mill was purchased by Falconbridge to process ore from their Hoyle Pond property. Kinross purchased the Hoyle Pond property and Bell Creek Mill from Falconbridge in 1992.The successful exploration program at Hoyle Pond has led to several expansions and process design changes, with further changes planned over the next twelve months.In 1994, the mine produced 61,865 oz. of gold at an average cost of 197US$ per oz. In 1995 production was 91, 611 oz. at a cost of 187US$ per oz. Projecting the nine months ended September 30, production for 1996 will be 155,000 oz. at a cost of 165US$ per oz.In early 1997, the CIP expansion will be complete, with a target of 175,000 oz. at a cost of 176US$ per oz for 1997. The mill throughput will have increased from 400tpd to 1500tpd between 1994 and 1997.The changes to Bell Creek since 1994 have been numerous with very little of the existing equipment still in operation. The total cost of the expansion to date is 15 million C$. This paper discusses the major projects carried out during in this time. The focus will be to highlight the justification of each project, the design and engineering, some of the initial start-up problems and solutions.Figure 3 shows a plan of the existing mill facility together with the various additions that were carried out."

Jan 1, 1997

By Alexander Levran

The main thrust of this presentation is to illustrate the growing contribution of solar energy to the mining industry by replacing existing mechanical and pneumatic tools and equipment with more effective and efficient electrical tools due to the increased efficiency and lower cost of solar energy generation. LCOE (levelized cost of energy/electricity) for solar energy is becoming highly competitive with other conventional sources of energy. The distributed architecture of solar power plants allows the supply of energy to highly remote and abandoned geographies. We will focus on the trend for this contribution to the mining industry over the next three years. Water desalination and delivery to the mining area will be topic of discussion regarding the contribution of solar systems in Latin America (LATAM) and other geographies. INTRODUCTION Increasing price pressure on the mining industry has generated a strong interest for mining companies to investigate energy costs and consumption. Currently, energy costs in mining economics contribute15% to 25% of the total commodity cost. In the past, most mines were operated by diesel gensets. Very high logistics costs for diesel supply, high and fluctuating diesel prices and theft led to very high energy prices. To overcome this problem, the mining industry has turned to solar energy, employing two main solutions: (i) adding a small scale (single level MWp energy supply) solar to an existing diesel system to create a hybrid solution operating as a microgrid environment; and (ii) replacing the existing diesel system with a large scale grid connected photovoltaic system financed by utilities or private IPP owners that signed a long-term power purchase agreement (“PPA”). In both applications, the near-term trend is to add storage and weather controls to optimize the electrical performance of the system. Use of concentrated solar solution (CSP) in the past was employed in a few remote sites to provide electrical energy to the mines. Currently this technology is not competitive with the photovoltaic (PV) systems. In some installations we have seen usage of a small hybrid system that is designed as relocatable, containerized and delivers scalable electrical power. In addition to the evolution of electrical energy sources, we see the trend of reduction of energy consumption in the mines by optimizing energy efficiency and generating load shifting solutions. Many studies of electrical energy in the mining industry support the growth of this trend in the mining industry.

Jan 1, 2019