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By Anthony J. Deevy

"Abstract -The Magino gold mine is located 45 km northeast of Wawa, Ontario. There was limit­ ed gold production in the Iate thirties. The present operation was officially opened in October 1988 and produced gold until September 1992. It was a 635 tonnes per day, decline-accessed mine, with ore coming from several small blast hole and shrinkage stopes.The host for the gold is the Webb Lake granodiorite stock which was intruded into the Goudreau Lake Deformation Zone. This east-northeast-striking deformation zone overprints the generally east­ west-striking isoclinally folded metavolcanic and metasedimentary rocks, which make up the east end of the Michipicoten greenstone belt. The ore-shoots are controlled by dextral delatancy associated with the Goudreau Lake Deformation Zone. Shearing, bleaching and silicification accompanied the gold emplacement."

Jan 1, 1994

By Baisheng Nie, Longlong Yang, Tao Yang, Wenjie Jia

"Gas adsorption in coal is an exothermic and physical process. Temperature might change during the dynamical process. In order to get the temperature variation of gas adsorption process, the experiment system which can test the temperature variation and analyze the thermal effect was established. Gas adsorption experiments under different conditions were done by using the test system. The results show that temperature increases during the adsorption process. It is an exothermic reaction process. Also, the temperature variation and the variation gradient increase with the increasing of equilibrium pressure. The temperature variation value is smaller if the experiment temperature is higher. The paper will provide basic experimental data for explaining gas adsorption mechanism better.INTRODUCTIONChina is the largest coal producer in the world while it also has the most serious coal mine disasters. According to the statistics, there are nearly a thousand coal mines in China including more than 110 the key state-owned mines risking to happen coal and gas outburst. Hundreds of coal and gas outburst occur each year which often causes serious casualties and economic losses (State Administration of Work Safety, 2007). With the continuing exploitation of the coal resources, the depth of the Chinese coal mines increases about 100 meters every year which causes the situation of gas accident becoming more and more serious (Xie et al., 2006).At present, the real mechanism of gas adsorption, desorption and the diffusion process in coal and the influence factor of it are not so clear. And because of the limit of prediction method and the technological level caused gas accident prevention theory and technology not so valid."

Jan 1, 2015

By Z. Farhat

In spite of advances in cutting tool technology, the understanding of the basic wear behavior and failure mechanisms needs further study. Tool wear is the main factor contributing to geometrical error and thermal damage in machined components. Manifested as a reduction in tool life, it also affects the workpiece surface finish, increases cutting forces and induces residual stresses. Furthermore, the emergence of high and ultra-high speed machining processes necessitates the investigation of tool wear under these severe working conditions. Tungsten carbide-cobalt composite material has been used traditionally as wear resistant materials for many years. One main application of this material is in cutting tools. WC-Co tools consist of hard WC particles imbedded in a tough Co matrix, which functions as a binder phase. More recently, Cubic boron nitride (CBN) tool material have attracted special attention due to its high hardness and excellent wear resistance. Boron nitride in its cubic form is known to be the hardest material next only to diamond. In this paper microstructural and tribological properties of commercial grade WC-Co and CBN cutting tool materials are investigated under high speed cutting conditions. The CBN cutting tools were found to be superior to tungsten carbide (WC) tools. Four-fold increase in productivity and significant reduction in chipping and cratering was achieved for CBN as compared to WC. Wear mechanisms are proposed and are related to the observed wear characteristics in the cutting zone.

Jan 1, 2006

By V. G. Papangelakis, M. Cheung, M. Dry

The high pressure acid leaching of laterite was modelled and simulated using a combination of two commercially available software packages, namely Aspen Plus 11.1 and the OLI Stream Analyzer. New kinetic parameters for the acid-controlled metal dissolution and precipitation reactions at temperature were first determined from previous experimental data on the leaching of limonite. A grain model with cylindrical pellets was used to model the solid-liquid dissolution reactions. Precipitation reactions were modeled via aqueous equilibrium chemistry. A dedicated thermodynamic database previously developed at the University of Toronto was used in conjunction with the OLI software to model the solution chemistry and calculate the concentration of hydrogen ions in solution at the leaching temperature. Mass balances were handled by Aspen Plus. The simulation gave good predictions of nickel dissolution under industrial and laboratory conditions, for the dissolution of limonite and limonite/saprolite blends. Computational

Jan 1, 2005

By Rick Coleman, Chelvan (Chevy) Veloo

"P.T. Freeport Indonesia's lrian Jaya Operation has been producing copper concentrate continuously since 1972. Numerous ore discoveries and five mill expansion programs have seen the initial milling rate of 7,200 MTPD escalate to the present rate of 125,000 MTPD, producing 2.5 million pounds of copper and 3,500 troy ounces of gold per day. The latest expansion, commissioned in February 1995, incorporates a 34 foot Semi- Autogenous Grinding (SAG) Mill, two 20'x30' Ball Mills, conventional roughing, cleaner column flotation, and attendant upgrades to the existing concentrate pumping and dewatering facilities. This paper will describe the SAG Plant flowsheet, and focus on the key training issues which contributed to a successful plant start-up.IntroductionP.T. Freeport Indonesia's operations in the Ertsberg mining district are located in the Jayawijaya Mountains of Irian Jaya, the easternmost province of the Republic of Indonesia. P.T. Freeport Indonesia (PTFI), the operator, is owned by Freeport MacMoRan Copper and Gold (81.3%), the Government of Indonesia (9.4%), and private Indonesian investors (9.4%). Geographical location, and sailing distances are provided on the attached location map.The operation stretches over 7 4 miles ( 114 km) from the dewatering and concentrate shipping facility at the Port of Amamapare on the Arafura Sea to the Grasberg open pit located at 3400m. The regional geology is covered in detail by Van Nort et al (1991 ), with current proven and probable reserves estimated at 1.13 billion metric tonnes grading 1.30% Copper, 1.42 ppm Gold, and 4.06 ppm Silver. The Grasberg open pit mining operation provides 92% of the mill feed, and is described in detail by Hickson (1991). The remainder of the mill feed is derived from several underground block caving operations. Current production rates provide a mine life in excess of 25 years. However, very favorable geology in the area leads to expectations that additional reserves will extend the life of the operation considerably."

Jan 1, 1996

By G. A. Young

THE Geological Survey was created in 1842 to aid the development of Canada's mineral resources. Although the institution has been in existence for nearly 100 years and has accomplished an immense amount of work, the need for its services remains as great as ever and, indeed, it is difficult to imagine a time when the country will no longer require a Geological Survey. This is so because of the tremendous effort required to make an adequate geological examination of so large an area as is embraced by Canada and partly because what today may seem an adequate geological examination proves, later on, to be inadequate. The ultimate objective of the Geological Survey is to complete the study of all phases of the geology of Canada, that is, to determine how and when the physical features originated, how and when the soils and other unconsolidated deposits were formed, and how and when the solid rocks and associated deposits were produced and assumed their present conditions. When the study has been completed, any only then, will it be possible to make a reliable estimate of the country's mineral resources. This appraisal embraces more than determining the value of already discovered deposits: it also involves attempting to establish what kinds of undiscovered deposits may be present and where they may occur. The estimating of the potential mineral wealth can be clone only after the geology of the country is known. Not until then will it be possible to forecast what types of valued deposits may occur in a district and what types will almost certainly be lacking. A thorough knowledge of the geology of the country is desirable not only to permit estimating the potential mineral resources but also as an aid in locating and developing mineral deposits whether these are of the nature of a bed of limestone, a seam of coal, a reservoir of petroleum, a vein, an irregular body of sulphides, or any other type of deposit.

Jan 1, 1940

By Roger V. Pierce

"WITHOUT mineral wealth, modern man would not exist. True, man could survive on a stone-age basis with an average life expectancy of, say, 25 to 30 years -once he got past infancy.However, no metal would tip his arrow in a hunt for protein; no steel plough would break the soil for the organized planting of seed; and no coal, nor oil, nor natural gas nor uranium fuels would pro-vide him with light or beat or safety from either beasts, or other men, or an unkind nature that threatened him and his family.Modern agriculture, fishing and forestry represent the other three wealth-producing industries. With-out metals, non-metallics and energy minerals, however, it would be impossible to fit any of these to man's modern needs."

Jan 1, 1967

By R. E. Bou Serhal

Many miners are exposed to dangerously high levels of noise on a daily basis. Over the past 15 years, a continually increasing number of occupational hearing loss has been reported from the mining community in the United States, of which, more than 95% is attributed to prolonged noise exposure. Although the noise exposure levels may differ between coal miners and metal and non-metal miners, in the absence of noise control at the source, the solution is the same: use of personal hearing protection devices (HPD). While protecting the miners? hearing it is also essential to no longer hinder their ability to communicate. With access to an advanced HPD that is customized to the miners? ears we are able to combine these two requirements. Using an intra-aural instantly custom molded HPD miners are protected from high levels of noise. The HPD is equipped with wireless capabilities, and contains both a speaker and an In-Ear Microphone (IEM). Therefore, the miners? speech may be captured from inside the ear and transmitted to the remote listener. This IEM signal is relatively noise-free since it is isolated from the background noise. The IEM speech signal, however, is ?boomy? and is missing some high frequency content, making fricative consonants hard to understand. Nonetheless, the IEM speech signal is correlated with the natural speech signal and may be manipulated through statistical techniques to more closely resemble natural speech. By improving the intelligibility and quality of the IEM signal, numerous applications may be enabled. One use of the enhanced IEM signal will be for radio communication. Using wireless radio communication in a noisy mining environment is sometimes the only practical and affordable solution to allow communication between miners equipped with personal hearing protection devices. Traditionally, one of the weaknesses of such wireless radio communication lies in the lack of designating receivers: whether they are the intended receiver or not, all those carrying a radio receiver are subjected to the broadcasted signal. The current work will detail a new concept of a "radio-acoustical virtual environment" where the radio signal will only be received by miners within a given spatial range, such range depending on the user?s vocal effort as well as the ambient and perceived background noise levels.

Aug 1, 2013

By Xiang-dong and Zhu, Xia-jie Hao, Yi-lin Fan, Quan Jiang, Lian-xing Hu, Xia-Ting Feng, Shao-jun Li

"Columnar jointed basalt (CJB), which typically originates from lava flows, is characterized by a special geological structure. The joint network inside the CJB is self-organized into a rough hexagonal arrangement. The field test and measurement during the unloading excavation showed that the columnar joint sets and other internal joint sets not only are important for determining the mechanical properties of the CJB, but also induced its asymmetric unloading deformation and failure. A constitutive model, which considered mechanical deterioration of both the joint sets and rock blocks, was also developed to simulate the unloading behaviour of the CJB. The crack-confinement supporting method for surrounding CJB was developed to overcome the failure of columnar jointed rock mass in the diversion tunnel. Application to the CJB segments of the diversion tunnels in the Baihetan project indicated that this supporting method was reasonable and efficient. INTRODUCTIONColumnar jointed basalt (CJB) rock mass, which typically originates from lava flow, is characterized by a special joint structure. The joint network of the CJB is self-organized into a roughly hexagonal arrangement and leaves behind an ordered colonnade. The widely accepted current view regarding the formation of columnar jointing involves a thermally induced contraction–cooling mechanism (Peck and Minakami, 1968; Degraff and Aydin, 1987; Budkewitsch and Robin, 1994; Lore et al., 2000; Goehring et al., 2006). Although the columnar basalt formation mechanism is fairly understood, the geotechnical characteristics of such rock mass are not well established. In practice, joint sets always induce the multi- failure modes of surrounding rock in the tunneling space (Ibarra et al., 1996; Waltham and Swift, 2004; Mahendra and Bhawani, 2008).According to conventional wisdom in rock mechanics, structural joints affect the mechanical response of rock mass by introducing strong anisotropic effects (Barton and Bandis, 1980; Hudson and Priest, 1983; Brady and Brown, 1985). The columnar jointed rock mass should be considered an anisotropic material given that the joint sets are distributed with some principal directions and characteristic spacing distributions (Cundall and Fairhurst, 1987; Hoek et al., 1998; Wu and Wang, 2001; Budetta and Nappi, 2011; Fortsakis et al.,2012). Columnar jointed rock mass would result in structurally controlled failure patterns, even serious disasters during underground excavation because of the low shear and tensile strengths of intensely joints (Gencer,1985 ;Ishida and Uchita, 2000; Jia and Tang, 2008). The CJB rock mass in the Baihetan hydropower station has exhibited serious stability issues, including sliding, fracturing and even collapse (Shi et al.,2008). Therefore, the geotechnical and geomechanical characteristics of such rock mass should be assessed through in situ investigation and numerical analysis to minimize future accidents during underground unloading excavation."

Jan 1, 2015

By W. B. Boggs

Part 1 Originally, the copper produced at the Noranda ?smelter was shipped in the form of blister bars to the Laurel Hill refinery of the Nichols Copper Co., New York. In 1930 a refinery was built at Montreal East for the purpose of refining Noranda copper and copper from the Hudson Bay Mining and Smelting Co., at Flin Flon. After investigation of the probable costs of making anodes at Noranda and at Montreal, it was decided to make them at Noranda rather than to continue to make blister bars there. Fuel is a major item of expense in making anodes: and since less fuel would be required in making anodes from molten copper than in making them from blister bars, a lower anode furnace cost could be expected at Noranda than at Montreal. Further, the expense connected with making blister bars at Noranda would be eliminated. The cost of treating anode and wire bar furnace slags is a serious item in a refinery, and it was found that the cheapest method would be to ship such slags back to Noranda. With the anode furnace at Noranda, much less anode furnace slag would be made at the refinery. Against these savings which would be effected by making anodes at Noranda must be set the high operating cost of an anode furnace at Montreal, using only tank-room scrap and the Flin Flon copper. This furnace would be handling a comparatively small tonnage and would have a high cost per ton. The usual equipment for making anodes from. liquid copper consists of either a stationary reverberatory furnace or a tilting Tacoma-type furnace together with an anode wheel of the Clark or Walker type. The reverberatory type of furnace has been developed from the furnace used in the old Welsh process of smelting and refining copper, while the tilting furnace is a development of the holding furnace, which is essentially a Peirce Smith converter without tuyeres and provided with burners.

Jan 1, 1932

By K. D. Peaslee

Slag splashing is an important development that has dramatically improved BOF vessel campaign life and reduced operating costs. This paper highlights research from physical modeling work using a 1/8-scale room temperature model BOF and slag characterization studies from several plants in North America and China. In the model studies, gas flow rate during blow and viscosity of the liquid were found to be two of the most important factors to changing the overall rate of liquid splashed onto the vessel sidewalls. When the flow rate was increased or viscosity decreased, the lower regions of the walls were splashed at a much greater rate. It was also shown that by changing the lance height, more liquid was deposited in the upper regions of the vessel at the expense of lower regions. Reducing the number of nozzles was found to be the most effective method of selectively coating a particular vertical section of the wall. Studies of BOF's using slag splashing in North America and China showed a difference in the melting characteristics of the final slag. Generally, slag splashing is successful when the melting point of the slag is 220-270°C below the tap temperature to maintain a balance between fluidity and refractoriness.

Jan 1, 2004

By Mi, Dong Liang, Jingyuan Bai, Victor Zhou, Xujun

Squirrel cage induction motors are the mostly used motors at present. Currently, the rotors of the squirrel cage induction motors are produced by aluminum die casting technique with the advantages of low cost of rotors. It is well known that the copper’s electrical conductivity is around 40% higher than that of aluminum. If copper is used to replace the current widely used aluminum in rotors, the total loss of motors will be reduced, hence increasing the overall motor efficiency. Copper rotors can be used to produce high efficiency and even super premium efficiency motors without enlarge the motor frame size. Considering the huge quantity of motors, the die casting process is the best solution to produce copper rotor with economic cost. Because of the characteristics of copper, it is difficult to produce copper rotors by casting similar to that done in aluminum rotors. In order to improve the die casting quality of copper rotor, a new tooling structure was developed and the casting process of copper rotor was simulated and analyzed by Any-casting software. The filling process, solidification process, inner gas distribution and residual melt modulus were analyzed. It was found that the design of symmetrical runner and inner runner on both sides was helpful to reduce the impact of molten copper to the cavity surface during the filling process. The use of Slag traps array can reduce die casting defects inside the end rings. That will be helpful to improve the rotor quality. INTRODUCTION Squirrel-cage AC induction motors are most widely used in the world. In 2017, the total installed capacity of AC motors in China has reached more than 1.2 billion kW, and the annual power consumption accounts for about 60% of the total national electricity consumption. To improve the efficiency of squirrel-cage motor will be helpful to energy conservation and environment protection. There are several ways to improve efficiency of induction motors, using copper rotor is one of the most effective solutions. It is well known that the copper’s electrical conductivity is around 40% higher than that of aluminum. If copper is used to replace the current widely used aluminum in rotors, the total loss of motors will be reduced, hence increasing the overall motor efficiency. Copper rotors can be used to produce high efficiency and even super premium efficiency motors without enlarge the motor frame size.

Jan 1, 2019

By L. Li

To accommodate the large payloads and harsh operating conditions associated with heavy vehicles in the mining industry, off-the-road (OTR) tires are typically used with heavy mining vehicles. These tires have increased abrasion and wear resistance due to their thicker tread, sidewall and bead thicknesses. Given these features, OTR tires are much stiffer than conventional passenger vehicle tires and cannot be mounted to a single-piece rim without damaging the structural integrity of the tire during the mounting process. Therefore, multi-piece wheels are used with OTR tires to facilitate mounting. While these assemblies are necessary, several instances of their failure have been reported to result in injuries or fatalities within the mining workplace. Many of these failures were specifically reported to be caused by the disengagement of the wheel lock ring - a component used to securely engage the assembly during operation. In this study, a threaded-connection locking mechanism has been proposed in place of the traditional lock ring design. The performance of this threaded-connection was numerically evaluated in a pull-out test against a conventional five-piece wheel assembly. The pull-out test was devised as a means of quantifying the engagement ability of each wheel?s locking mechanism. A high degree of modelling accuracy was maintained throughout the analysis by validating the vertical and horizontal static loaddeflection behaviour of the rim model of the five-piece wheel assembly against experimental data. Through validation, the model data were found to be within 10.5 and 4.80 %, for vertical and lateral loaddeflection behaviour, respectively. Results from the pull-out analysis found that the threaded-connection demonstrated a 113 % increase in the force required for disengagement to occur relative to the conventional five-piece design - a force of 9,550 kN in total.

Aug 1, 2013

By K. S. Raja, B. Pesic, S. Kshetri

"We investigated the electrochemical corrosion behavior of commercial permanent magnetic material (NdFeB alloy) in 0.1 M NaH2PO4 solution (pH:4.75) containing 0 – 1000 ppm of chloride at room temperature (298 K). The material was evaluated in magnetized and demagnetized condition with different surface preparations such as: Ni-Cu-Ni coated, uncoated (bare), and anodized (in fluoride containing ethylene glycol at 60 V for 15 minutes to form a thick nanoporous oxide surface). The nickel coated magnetic sample showed reasonable pitting corrosion resistance up to 100 ppm chloride addition. The uncoated samples showed passivity in chloride free phosphate solution. Chloride additions caused pitting and the pitting protection potential was equal to the corrosion potential with 100 ppm chloride addition. Demagnetization did not alter the electrochemical polarization. However, the passive film formed on the magnetic sample showed higher charge carrier density than the film formed on the demagnetized sample. INTRODUCTIONSintered NdFeB permanent magnets exhibit excellent magnetic properties such as large energy product [(BH)max > 450 kJ/m3], high saturation magnetization (1.6 Tesla), and high coercivity (1.2 – 2.08 x 106 A/m) (Sugimoto, 2011). However, the NdFeB magnets are prone to corrosion attack because of the presence of Nd-rich intermetallic phases, such as Nd4Fe (Jurczyk & Jakubowicz, 2000). Nd-rich and B-rich intermetallic phases are distributed in a matrix of Nd2Fe14B tetragonal ferromagnetic compound in a permanent magnet. Generally, several types of Nd-rich phases are present in the magnet with Fe:Nd ratios ranging from 1:1.2 to 1:7. The volume fractions of Nd-rich and B-rich (Nd1+xFe4B4 type) phases are about 10% and 7% respectively (Li, Ma, Li, & Wang, 2011) . Among these intermetallic phases, Nd-rich phase has the most active electrochemical potential. Therefore, dissolution of this phase occurs in preference to other phases by galvanic corrosion when exposed to moisture. Since Nd-rich phases are present at the grain boundaries of the Nd2Fe14B matrix, corrosion leads to disintegration of the magnet."

Jan 1, 2012

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 A. J. Hyett, R. D. Reichert

"A laboratory and field research program was conducted to investigate the major factors influencing bond capacity of grouted cable bolts. The results indicate that cable bolt capacity most critically depends on the grout uniaxial compressive strength (UCS), the radial confinement, and the embedment length.In the laboratory &apos;split-pipe&apos; tests were conducted using P VC, aluminum and steel pipes to provide radial confinement, and field test sites were chosen in granite, limestone and shale rock masses. For both datasets higher capacities were obtained under conditions of higher radial confinement. A correlation between the two was obtained through a comparison of the radial wall stiffness of the laboratory pipes with that of the field boreholes as measured using a high pressure dilatometer. Cable bolt capacity was found to increase with embedment length though not in direct proportionality.The use of low water cement ratio grouts (<0.40) can increase cable bolt capacities by 50% to 75%. This effect is maximized under conditions of high radial confinement. However, the use of super thick grout paste (0.30 and less) may be both impractical and undesirable, first because of their limited pumpability and second because of their inconsistency in strength. Grouts with a water cement ratio of between 0.35 and 0.40 are recommended for practical cable bolt applications."

Jan 1, 1992

By Fred E. Gray

The mill of Bralorne Mines, Limited, is located on the government highway in the Bridge River mining district of British Columbia, approximately fifty miles northeast of Shalalth, the shipping point on the P.G.E. railway. Prior to 1931, the property now owned by Bralorne Mines, Limited, was operated by Lorne Gold Mines, Limited. During the early operation of the mine, the ore had been treated at various times in one of three small amalgamation mills on the property. With the succession to ownership by the Bralorne Mines, Limited, work was started on construction of a new mill of approximately 100 tons capacity per day. The new mill was put into operation in the month of February, 1932, and since that date has been in continuous operation, milling an average of slightly over 3,000 tons of ore a month. The ore treated in the Bralorne mill is a gold-bearing quartz containing a very small amount of silver. About 75 to 80 per cent of the gold is in the form of free gold, the principal remaining portion being intimately associated with pyrite and arsenopyrite. The gangue rock is quartz, together with varying but relatively small amounts of altered diorite or albitite. In some of the ore, usually the higher grade portions, there is also considerable talc, which forms much slime in grinding. The mill is situated near the portal of the main haulage tunnel and the ore is received directly from the mine ore-trains, which dump on to the grizzly over the coarse-ore bin of the crushing plant. Figure 1 shows the flow-sheet of the mill as it is now being operated. Various changes have been made in the flow-sheet and in the reagents since the commencement of operations, and doubtless minor changes will continue to be made in order to increase the efficiency of the mill. Among the more important changes were those from two-stage to single-stage grinding, and from amalgamation plates to blankets. The change in the crushing was made because too much crushing was done when both primary and secondary mills were employed.

Jan 1, 1933

By C. Liu

Zeta potentials and settling rates of an oil sands tailings sample taken from Syncrude Canada Ltd&apos;s Aurora Stacker Pilot Operation were studied. Two clay minerals, kaolinite and illite, were also studied since these are the major constituent minerals in the fine oil sands tailings. Process water, decanted water as well as distilled water were used. It was observed that the zeta potentials of the tailings solids showed maximum negative values in process water at pH 8-10, which coincides with the pH of commercial hot water bitumen extraction process. The settling rates of the tailings sample were very low, at 0.008 m/hr in decanted water and 0.04 m/hr in process water. The rates were increased to 1.0 m/hr in decanted water and 0.13 m/hr in process water at an addition of 50 g/t Ciba AF1235. Although the settling rate was higher the supernatant was cloudier in decanted water than in process water. Further increase in the dosages of Ciba AF1235 did not increase the settling rates in decanted water but gradually increased it in process water, reaching 0.46 m/hr at 100 g/t. The results indicated that lower concentrations of Ca2+ and Mg2 (in decanted water) benefited settling rates but did not benefit supernatant clarity. Test results also indicated that Ciba AF1235 caused selective flocculation of the tailings sample, since the top sediments had higher illite and lower quartz contents than the bottom sediments.

Jan 1, 2006

By T. C. Holmes

Introduction The Dome mine, in the Porcupine mining camp of northern Ontario, is one of the important gold mines of the country, having produced over 139 million dollars worth of gold from the commencement of production in &apos;1910 to the end of 1944. The geology of the mine is complex and a number of types of ore are known, each occurring under particular conditions. The mine workings are very extensive and by far the greater part of them have been geologically mapped only in reconnaissance fashion. By 1940, when the writer joined the mine staff, the orebodies in the sedimentary trough and the &apos;nose&apos; orebodies, the first types to be developed, were almost worked out and many workings were inaccessible, so the descriptions of these types are based largely on study of the plans and records. The same applies to a lesser extent to some other types. At various places in this paper, statements are made as to the mineralogical or chemical composition of the rocks. Most of these determinations are based on examinations made with a hand lens and cannot, therefore, be regarded as very reliable. General Geology As there are several types of ore in the mine, occurring under quite diverse conditions, a brief outline of the geology is given here, sufficient to provide a general picture into which the fuller descriptions given with each type of ore can be fitted.

Jan 1, 1947

By P. J. Le Roux

"Mining worldwide and definitely in South Africa, is constantly under pressure to reduce its cost structure so as to sustain profitability. In underground gold mines where an open stope mining method is employed, dilution often has a significant effect on the viability of sustaining profits. Target Mine practices Open Stope mining Method and it was found that in some open stopes dilution was in excess of 10%, which has a significant impact on the sustainability of the mine.Dilution in excess of 10% can result in the reduction of the recovered grade from 5,5 to 4,5 grams per ton (g/t). The reduction of 1 g/t in recovered grade results in a potential loss of about ZAR21 Million per month bases on a gold price of ZAR240 000 per kilogram. Based on Life of Mine projections the potential loss of income could be as much as ZAR3,3 Billion. A reduction in dilution would have the opposite effect. There are a number of factors which affect dilution of which falls of ground in open stopes is a major contributor. The falls of ground can be attributed to a number of factors such as beam failure as a result of a larger than normal expected roof area (hydraulic radius too large), poor ground conditions, and poor blasting. The cost of damage to or loss of trackless equipment as a direct result of the falls of ground in open stopes, is very significant. The review of financial figures has indicated that this could be as high as ZAR491 million. This combined with the added cost of transport, hoisting, secondary blasting, milling and plant treatment costs of ZAR293 results in an estimated opportunity loss of ZAR784 million.Currently there is a significant amount of data available in the mining industry which could be effectively used to develop suitable back analysis techniques but to date this has not been used effectively. If dilution can have such an impact on current and future mining ventures then the optimization of back analyses for the prediction of dilution in open stoping could assist significantly in the reduction of dilution in massive open stopes. Rockmass classifications, geotechnical information, blast techniques, blast design, the stress strain environment and hydraulic radius all have an effect on, or play a role in the evaluation of dilution. Each of these factors will be taken into consideration to ultimately determine a measurable or calculated percentage of dilution in massive open stopes.The amount of overbreak in an open stope can be determined by subtracting the planned stope volume in m3 from the actual measured final stope volume in m3, which is obtained from the CMS (cavity monitoring system). This is in turn divided by the planned stope volume in m3 to determine the percentage overbreak. The CMS wireframe is imported into the geological model and its grade re-evaluated. From this the actual percentage dilution for this open stope can be determined. The dilution obtained can result in a major reduction of recovered grade for the open stope, but can also increase the recovered grade. The latter is normally the exception rather than the rule.When analysing data from Target mine the following was achieved:• Using 11 years of data a method of measuring and predicting the percentage dilution in open stoping was developed. This took into account rock mass quality, stress-strain state, and the hangingwall hydraulic radius (size of stope hangingwall exposed).• Implementation of this prediction method resulted in a reduction in falls of ground in open stopes. The benefit of this was a reduction in the damage to mechanised equipment resulting from less falls of ground which had a positive effect on the profit margins of the mine. As a direct result the recovered grade from the open stopes increased due to the reduction in the amount of dilution.• A design criterion, Dilution Stress-Strain Index (DSSI), was developed which allows the user to calculate, with certainty, the stability of the open stope and determine if m"

Jan 1, 2015