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By Brett Triffett, Mark Weidenbach, Christopher Treloar

OZ Minerals owns and operates the Prominent Hill copper-gold concentrator in South Australia, built in 2008 and commissioned in early 2009. The concentrator operates via semi autogenous grinding in a thirty four foot ThyssenKrupp Polysius mill followed by a twenty four foot Polysius ball mill in closed circuit with hydro cyclones, designed for an ore throughput of eight million tonnes per annum. The main aspects of designing the circuit are discussed along with the issues faced in the early stages of operation. A review of the optimization strategy applied to the milling circuit such as cyclone optimization, advanced process control strategy implementation and reline management to improve availability is then discussed highlighting areas of significant process improvement that have seen the plant exceed nameplate throughputs above nine million tonnes per annum.

Jan 1, 2012

By Martin G. Wafforn, George J. Greer

"In early 2014, Pan American Silver Corp. commenced a project to construct a second shaft at its La Colorada underground mine located in Zacatecas State in Mexico. This was the first new shaft development project undertaken by Pan American Silver in the history of the company. The existing mine workings permitted the use of a raise bore for the excavation of the shaft opening, utilizing directional drilling in poor ground conditions to advance the pilot hole. This was an interesting project with many challenges and successes, and numerous lessons learned. The project was successfully completed in 2016, with the shaft operating at full mine production capacity within weeks. INTRODUCTION The La Colorada Mine has a long history dating from at least the 1920’s. The mine is located in the northern portion of Zacatecas State in Mexico in the Chalchihuites area, an approximate two hour drive south from the city of Durango. Pan American Silver acquired the La Colorada mining concessions in 1998, with mine production at that time consisting of only a few hundred tonnes per day. Over the course of the following 15 years, with the addition of an oxide processing plant and some expansions to the sulphide processing plant and site infrastructure, production was eventually increased to a maximum of 1,250 tonnes per day, all of it generated from conventional cut-and-fill stopes in the underground mine. An existing shaft was used to hoist the ore to surface, and over the years Pan American Silver had deepened the shaft and had changed out some of the hoisting plant. However, there were historic workings in close proximity to the shaft that made it unsuitable for personnel transport, and shaft maintenance was becoming difficult. The shaft was increasingly considered as a risk to the long term production continuity, and also to further deepening of the mine. In addition, expanding the capacity of this old shaft was not possible. Drilling of the La Colorada mineralization at depth commenced in 2010, with very good exploration success. As a result, by the end of 2013, the mine reserves had grown to a total of 6.5 million tonnes of high grade ore (388 g/t Ag, 0.36 g/t Au, 2.4 % Zn, and 1.3% Pb). Furthermore there were more (and higher grade) sulphide reserves than oxide reserves at depth. Following the completion of an internal study in 2013 with assistance from one of the international shaft contractors, a decision was made to increase the production from the mine with the construction of a new shaft and a new sulphide processing plant, a project with a calculated payback of 2.2 years."

Jan 1, 2019

By K. C. Sole

In most copper solvent-extraction operations, an important consideration in choice of extractant is the requirement for high selectivity of copper over iron. Ester-modified aldoxime extractants presently offer the best Cu:Fe selectivity. In some plants, however, the process feed liquors contain significant amounts of manganese but little iron. Although manganese is not chemically extracted by oximes, trace amounts are carried over to the electrowinning circuit by physical entrainment. This may result in anodic oxidation of manganese which, in turn, can cause oxidative degradation of the organic phase when returned to the solvent-extraction circuit in the spent electrolyte. Many of these operations prefer to operate with higher levels of iron reporting to the advance electrolyte, as appropriate control of the Fe(II)/Fe(III) couple will ensure that manganese remains in the benign Mn(II) form. A new reagent, LS 4202, designed by Cytec, now offers the possibility of tailoring the iron co-extraction, so that appropriate Cu:Fe selectivity can be achieved in the solvent-extraction operation to maintain an electrolyte Fe:Mn mass ratio of >10:1, while retaining the other benefits offered by ester-modified aldoximes. The results of an integrated solvent extraction-electrowinning pilot-plant trial are presented, in which the performances of the conventional extractants ACORGA® M.5774 and LIX® 984N are compared with LS 4202. The Cu:Fe selectivity is demonstrated, along with results on the transfer of other impurities to the advance electrolyte.

Jan 1, 2007

By Parsons. Robert B.

"Starting this year, corporations that conduct business in Ontario face a new tax a corporate minimum tax. This tax is in addition to the myriad of other taxes that make up a corporation's total tax burden including federal and provincial capital 1oXJ!S, payroll tax and sales taxes. Mining companies with gross revenues in excess of $10 million or total assets exceeding $5 million may be liable for this new tax. IntroductionOn December 8, 1993, the Ontario government introduced legislation to implement the corporate minimum tax (CMT promised in its May, 1993 budget. There are very few differences between the final legislation and the budget proposals.The CMT is effective for taxation years commencing after 1993. Subject to certain specific exemptions (detailed below), the tax applies to all corporations liable for Ontario Corporate Income Tax that have either gross revenues in excess of $10 million or total assets in excess of $5 million. These measurements apply to the aggregate gross revenues and total assets for all corporations in an associated group and a corporate partner's share of partnership assets and revenues must be included in the determination.In essence, the CMT is an income tax that is based on financial statement profit instead of an income amount that is determined separately under a statute. Accordingly mining companies (including so called ""junior"" exploration companies), which traditionally sheltered their taxable income by claiming generous exploration and development deductions, could find that they have a CMT liability."

Jan 1, 1994

By M. Oliazadeh, A. Vazirizadeh

"The inclusion of small amounts of silicon, phosphorus and sulphur in iron ores or concentrates can have a profound effect on the steel making process and thus on the final iron and steel products. In nature however, it is inevitable that iron deposits contain unwanted elements. Each element has its own distinct effect on the final steel product. The effect of high silicon is the formation of gray iron. Phosphorus mainly increases hardness and strength, lowers solidus temperature and increases fluidity and cold shortness. Finally sulphur contamination causes cracks in the iron texture when smelting and forms white iron when casting. Overall, the acceptable level of phosphorus, sulphur and silica in the iron concentrate should be less than 0.04%, 0.15 % and 1.5 % respectively.Scarcity of high grade iron ores necessitates using lower grade ores with higher amounts of impurities. The purpose of iron concentrators is to increase iron grades to an appropriate level suitable for steel making as well as removing impurities. Although many impurities can be traced in the ore, the most predominant impurities are limited to one or two elements. In this paper the beneficiation methods for removing SiO2, P and S are presented, including flotation, and the parameters that need to be considered in the design of beneficiation plants are discussed. Finally industrial cases are discussed along with their metallurgical performance.INTRODUCTIONIn metal sector, value of iron ores and concentrates is determined by iron percentage as well ascontent of:• Useful elements (Mn, Ni, Cr, V, Ti): natural alloying elements in steel• Deleterious impurities (S, P, As, Zn, Pb, K, Na): impair metal properties or complicate operational process in blast furnace• Fluxing components (Si, Ca, Mg,, Al)Sulphur and copper result in red-short, phosphorus is the cause of cold brittleness and arsenic and copper decrease welding characteristics. Sulphur should not exceed 0.15 in commercial ore. Acceptable sulphur content in ores and concentrates for producing sinter and pellets is 0.6%max, as sintering and heat hardening of pellets remove sulphur 60-90%. Phosphorous content in ores, sinter and pellets is limited to 0.07%-0.15%. 0.00.1% As max, 0.1-0.2% Zn max and up to 0.2% Cu are allowed in iron-ore part of the blast furnace burden for the production of standard conversion pig iron. Slag-forming components are divided into basic oxides (Ca, Mg) and acidic (Si, Al). Higher ratios of basic to acidic oxides are preferred since this reduces raw fluxing material."

Jan 1, 2016

By S. E. Malouf, R. Hinse

"The Mineral possibilities of the Chibougamau area were first recognized by Richardson in 1870 and Low in 1885, both of the Geological Survey of Canada. The first record of interest by the Quebec Bureau of Mines is in 1904, when J. Obalski reported on the discovery of copper and asbestos by Peter McKenzie in the previous year. Reports of 1906 and 1907 covered the McKenzie Gold Mine find and other deposits. In 1908 Prof. Dulieux described the quartz vein on Merrill Island and the mineralized zone on the near-by mainland. In 1910 the Chibougamau Railway Commission, though commenting favourably on the possibilities of the area, concluded that a railway was not then warranted.In spite of this, prospecting in the district continued. The main Campbell Chibougamau deposit, the Blake showing on Merrill Island in Dore Lake, was found in 1920, and other discoveries were made soon after. Between 1927 the work of Mawdsley, Retty, and Norman tor the Geological Survey and the Quebec Bureau of Mines stimulated further interest. In 1934 Consolidated Chibougamau Goldfields Ltd., a subsidiary of Consolidated Mining and Smelting Co. of Canada Ltd., acquired the Merrill Island and Cedar Bay holdings of Chibougamau Prospectors Ltd. They embarked on an aggressive campaign, directed essentially at the gold quartz veins at Cedar Bay. Exploration there included a 522-foot shaft, 4,732 feet of drifts and crosscuts, and about 34,000 feet of surface and underground diamond drilling. Thirteen holes were also drilled on the replacement sulphide lens at Merrill Island. Operations were suspended in 1936, as the occurrence was too low grade for development at the existing metal prices and under difficult operating conditions.The completion of the Quebec Bureau of Mines highway from St. Felicien to Chibougamau in 1950 was followed by a project of detailed geological mapping by the Bureau. It also encouraged Campbell Chibou-gamau Mines to acquire the assets of Consolidated Chibougamau Gold-fields and commence a program of surface exploration. Between August 1950 and April 1951, 41,183 feet of diamond drilling was done on the Cedar Bay and Merrill Island holdings. The Blake showing off the west shore of Merrill Island developed at depth into a major orebody. A lease was obtained on adjacent ground from Merrill Island Corporation, and underground work commenced in November 1951. Development at Merrill Island to June 1st, 1955, included a four-compartment shaft to 1,225 feet, with 8 levels at 150-foot intervals, 5,317 feet of raises, 16,709 feet of drifts and crosscuts, 52,514 feet of surface and 96,593 feet of underground diamond drilling."

Jan 1, 1949

A Joint Venture between Hope Bay Gold Corporation and Miramar Mining Corporation recently acquired the Hope Bay project in Nunavut, which represents the first discovery of a major new Archean greenstone gold belt in Canada since the discovery of Hemlo in 1982 and the Yellowknife belt in 1938. Located some 685 km North of Yellowknife, the Hope Bay Belt is geologically comparable to the other major gold producing regions of Canada. The initial discovery of gold mineralization in 1992 led BHP to acquire virtually all of the Hope Bay belt. Over the subsequent 6 years, BHP expended C$85 million on exploration, including 180,000 meters of drilling, 2.3km of underground workings and a 27,000 tonne bulk sample, as well as extensive environmental and economic studies. Hope Bay Gold and Miramar acquired the Hope Bay property in December 1999 for a cost of C$27 million, considerably less than the C$85 million spent by BHP in exploring the property. They both hold 50% of the project, and share expenses equally. Hope Bay Gold is the manager of all exploration phases and Miramar will manage feasibility, construction and operations. The Hope Bay Joint Venture controls 1,117 sq. km., covering virtually the entire 80 km long Hope Bay and adjacent Elu greenstone belts. We believe that Hope Bay is one of the best-undeveloped gold projects in Canada. Work to date has defined a global resource in excess of three million ounces of gold in three principal deposits, each of which is open to extension along strike and to depth. A C$17 million work program for year 2000 focused on advancing a significant portion of the gold resource to a measured and indicated category. This will provide the basis for initiation of a feasibility study in 2001. The 2000 drill program was one of the largest undertaken in Canada last year, and is a clear indication of our confidence that Hope Bay will develop into a major gold producing district. The majority of the potential mineable areas known to date lie within 350m of surface and would be accessed through a combination of open pit and declines. Currently, development of a 1,800 to 2,000 tpd gold mine producing in excess of 300,000 ounces of gold per year at cash costs below $US200 per ounce is envisioned. In addition, the exploration potential on the 80 km gold belt at Hope Bay is clearly tremendous.

May 1, 2001

By T. Patching

"MINING operations at the Star Key Mine provided an example of a small-scale prairie-type coal mine that employed several interesting procedures and achieved good productivity with low capital expenditures. The mine was located about 11 miles north of the city of Edmonton, on the north side of the Sturgeon River valley. It opened in 1945 and operated until 1979. Output in the winters reached about 500 tons a day in the late 1940s, but in the spring and summer periods activity was usually limited to only servicing and development work. In the later years of the mine's life sales fell to less than 100 tons per day. Most of its output was bought for domestic use in furnaces and stoves so production of large sizes was desired. A modest market for stoker coal did exist for a time. Screenings (-5 / 8 in.) were sold to the city's power plant until it converted to natural gas and were also used for thawing frozen ground for work on pipelines. These markets were comparatively small and the small sizes did not command as high a price as did the larger sizes. However the extension of natural gas services to rural markets cut into the domestic heating market and finally led to closure of the mine. The coal was strong when freshly mined, but because of its high inherent moisture content, about 25%, it did not store well on surface but tended to disintegrate. It was of subbituminous Crank with a heating value of about 8000 Btu per pound and burned with a clean flame. The seam mined was in the Edmonton Formation, of Upper Cretaceous age, at a depth of 60 to 80 ft below the surface. The seam in the mine area was about 11 feet in thickness but thinned gradually to the north and south and split to the west (1). It was approximately horizontal but gentle rolls in the floor of several feet in height necessitated brushing in places to produce suitable haulage grades. The floor material was of bone and clay, overlying a thin layer of coal. Above the seam there were only a few feet of mudstones and weak sandy shales while the remainder of the overburden was clay and unconsolidated glacial till and surface soil. Because of the soft floor and weak roof material the miners usually left about a foot of coal in the floor to provide a firm working surface and about a foot of coal above the rooms and two feet of coal above the entries to provide a competent roof."

Jan 1, 1985

By K. E. Haque

"Radium is selectively leachable from uranium ores with various types of lixiviants. Among a number of lixiviants tried on Midwest Lake uranium ore, KCl provided the highest per cent of radium extraction (60%-65%). Leach results further confirmed that a certain portion of Ra is not amenable to KCl leaching. More than 99% of the dissolved radium could be removed by treating the KCl leach liquor with barite or with radium selective complex resin (XFS-43230 resin of Dow Chemical Inc.) or by precipitating as RaBaSO4. Uranium leachings from the Ra-preleached uranium ores indicate that radium leaching prior to uranium may be applied as an extension to the conventional or alternative (i.e. acid chloride) leaching process of uranium ores in order to yield environmentally acceptable tailings (in terms of radium in the solids).IntroductionAt present, radium is considered as an environmental issue, particularly for uranium ore mine mill operations, rather than a commercial commodity. Radium was once a highly priced commodity ($180/mg during the first great war) but now it hardly has any commercial value. Its principal applications were in the field of cancer treatment and in the manufacturing of lwninous dials for watches. Nowadays readily-available synthetic radioisotopes are finding applications in place of radium.Because of scarcity and high toxicity, further commercial applications have never been explored.Radium was first discovered and extracted from uranium ore by P. Curie, M. Curie and G. Bement in 1898. Radium is widely distributed in nature but in exceedingly minute quantities. It is one of the daughter products of uranium or thorium and its maximum concentration is 3.3 x 10-7 part/part of U(21). Because of its short half-life (approximately 1620 years) in a geological time scale, its occurrence in nature as a distinct mineral is most unlikely.The details of the original radium leaching process developed by the Curies and Bernont are in the literature. This process essentially involved the roasting of uranium ore with caustic. carbonate followed by sulphuric acid leaching. The precipitated RaSO4 and BaS04 were treated with boiling Na2CO3 to convert them into the corresponding carbonates which later were dissolved in HCI. RaCI2 and Ba02 were separated and concentrated from the chloride liquor by fractional crystallization. But, in the course of time several modifications were made or proposed to the original process. Regardless of the process employed 226Ra extraction from the uranium ore was seldom better than 90%, and further as much as 20% 2URa loss took place during the concentration and purification process."

Jan 1, 1987

By Changmiao Liu, Dong Dong

"Magnesite is a major mineral resource in China, whose output and export are massive and quite important to the world. Flotation performances of eight anionic collectors on magnesite were studied to find the proper ones. Micro-flotation results indicated that collectors of HOl, SDBS and AEP had outstanding flotation performances on magnesite, with the recovery ratio all reaching above 90% in a wide range of alkaline pulp. Solution chemistry calculation, Zeta potential and FTIR measurements were employed to reveal the interaction mechanism between anionic collectors and magnesite surfaces. Solution chemistry analysis indicated that the main active components of HOl, SDBS and AEP were anions and association complex anions in alkaline pulp. Magnesite surface was negatively charged in the alkaline pulp. The active sites on magnesite surface were mainly the components of MgOH-, Mg (OH)2, and MgCO3 when the pulp pH was over 8. Anionic components of HOl, SDBS and AEP reacted with Mg in magnesite surface to make the insoluble anionic salts. And the chemical adsorption was confirmed by the FTIR measurement evidences.INTRODUCTIONAs an important industrial mineral, magnesite has been widely applied in metallurgy, building materials, chemical industry, agro-pasturage and other fields (Hu et al., 2006). It is a major mineral resource in China with abundant reserves. Its output and export are massive and quite important to the world. Liaoning province is rich in magnesite, whose reserves and production both come first in China. So far the proven reserves have reached 2.91 billion tons, accounting for more than 90% of total reserves in China, and more than 25% in the world (Li et al., 2012).Magnesite ores in Liaoning province mainly contain crystalline magnesite, and the gangue minerals of quartz, dolomite, talc, tremolite, chlorite and carbonaceous materials. Some ores also contain a little pyrite, chalcopyrite, hematite and apatite. Most of the ores must be preprocessed to separate the useful parts from the large amount of gangue minerals, so that their value and industrial application can be enlarged and promoted.Flotation is commonly used to process the magnesite ores, and the conventional flotation methods include anionic and cationic flotation. In the former, gangue minerals of silicates were separated by using amine type cationic collectors. After the impurity minerals were removed, high qualified magnesite concentration could be gained. For the cationic flotation method, it had some drawbacks of lower recovery ratio and poor performance in the lower temperature pulp (Li et al., 1995)."

Jan 1, 2016

By S. Bantubani, I. Mc Dougall, S. Arjun, H. Joubert, R. Hansraj

The requirements determining the design of the Söderberg electrode columns used in base metal applications are different to those of other industries. There is a strong trend to position the contact shoes above the furnace roof in order to reduce the risk of water leakages directly onto the furnace bath. Tenova Pyromet has adapted its proven electrode column design for application on base metal electric furnaces based on these requirements. The design modifications implemented as well as considerations regarding the overall electrode-roof-furnace arrangement are discussed. Equally important is the management of the Söderberg electrodes to prevent over or under baking. Tenova Pyromet has developed the AutoFurn™ furnace controller to not only optimise furnace operations, but to improve electrode management. An overview of the electrode management control philosophy implemented by AutoFurn™ is provided, focusing on intelligent electrode regulation, slipping and baking. INTRODUCTION Tenova Pyromet has developed an electrode system for use in base metal furnaces, which builds on the experience that Tenova has gained during the past 30 years with electrodes in the ferroalloy and base metals industries. In base metals applications, an important safety consideration is the minimization of water within the furnace and on the furnace roof. In addition, direct contact between copper equipment such as contact shoes and pressure rings and the contents of the furnace is discouraged. In a 3 phase AC furnace, three electrode columns transfer the electrical energy to the furnace bath. Both Söderberg and prebaked carbon or UHP graphite electrodes are in use in base metal furnaces. In each column, the electrode is held in position by a hydraulic slipping and regulating device, a pressure ring and contact shoes. The electrodes can operate in a submerged-arc or brush-arc configuration, where the electrode is immersed in the slag or a short distance above the slag (Mc Dougall 2013). The electrode equipment is divided into an upper and a lower electrode assembly. The self-baking Söderberg electrode is made from lengths of steel casings that are added to the top of the electrode column and welded into place. Carbon electrode paste is added to the inside of these casings and is baked to form a solid tip in the region of the contact shoes. The working platform that surrounds the area where new electrode casings are added, is electrically isolated from the building and each electrode is isolated from the others to ensure the safety of the personnel who perform the electrode casing additions.

Jan 1, 2019

By A. Mcdonald

"An X-Met Analyzer was purchased from Outokumpu in late 1983for use in the Hudson Bay Mining and Smelting smelter. Its first use was in the fuming plant to give zinc assays of each charge of slag tapped from the fuming furnaces. This quickly told the operators exactly when each charge had reached its economic tap-out point, and gave supervision a fool-proof method of identifying good operation. These and other factors led to major improvements in coal utilization in the fumers and to major increases in zinc oxide production. A second unit was later purchased for the reverberatory furnace to give silica and iron assays of the slag, and these were used to make adjustments in the feed composition to maintain the desired SiO2:Fe ratio in the slag. Since purchasing the units for the furnace, the oil consumption and copper content of the slag have dropped significantly. IntroductionSmelters have lagged far behind concentrators in process control by mean s of rapid product analysis. The on-stream X-ray analyzer was developed about seventeen years ago, and soon concentrators around the world were getting assays of the incoming ore, .concentrates and tailings every fifteen minutes, and using these to control reagent additions and other process variables. Almost always, the concentrate grade and recovery improved.In smelters, product streams are solids or molten materials, not the more easily handled slurries, and until seven years ago no inexpensive equipment was available to provide rapid analysis of this type of material. In approximately 1980, several companies developed instruments based on irradiating solid samples with low-intensity gamma rays from radio-isotope sources, and measuring the secondary X-rays emitted from different elements in the sample to provide an analysis of the elements desired.The smelter staff had a close look at what was needed and listed the following points as being critical:1. ability to provide Zn assays of a sample of slag within 15 minutes of taking it, in order to achieve optimum fuming times (zinc fuming , being a batch process, had the greatest potential benefit from rapid slag analysis);2. ability to give Cu and Fe assays on the slag, and on other smelter products, such as matte and converter slag;3. ability to give Si02 assays since the SiO2 content of the slag has a strong effect on fuming rate; and4. ability to stand up to an industrial atmosphere such as exists in the fuming plant."

Jan 1, 1987

By Ferri P. Hassani, Riadh Bouzaïene

"Selected methods of pressure loss predictions in horizontal slurry flow in pipelines are presented. For a given combination of flow velocity, solids concentration and particle size, the slurry and its flow conditions are described, and an appropriate method of pressure loss prediction is outlined. The wide range of conditions treated in this paper may be found in practice in areas varying from the hydraulic transport of low concentration slurries to dense-phase conveying of paste backfill in underground mines.IntroductionThe hydraulic conveying of solid particles in pipelines is a major component of the mining and mineral processing industry. Whether the objective is to transport ore to the processing plant or to make use of mill tailing as backfill material; the need for well designed, economical hydraulic conveying systems is recognized.The contribution of this paper is part of an on-going research program at McGill University involved in optimizing and developing techniques for total mine waste disposal. One of the main concerns in the conveying of solid-liquid mixtures is the prior knowledge of the pumping power input required. This energy requirement is directly proportional to the pressure losses incurred in the pipeline system. Understanding the sources of such pressure losses and predicting their magnitudes should enable the system designer to make informed decisions regarding the optimum mode of hydraulic transportation commensurate with the over-all requirements of the operation.This paper is an attempt to classify pressure loss prediction methods encountered in the literature for solid-liquid mixtures. In spite of the large number of publications spanning thirty years of research in the field of slurry transportation, it is sometimes difficult to correctly identify the appropriate methods applicable to a given situation. This is partly due to the inherent complexity of the mechanics of slurry flow and the ensuing uncertainty about the nature of the flow regime under investigation.Our approach is to use three fundamental parameters, namely: flow velocity, solids concentration and particle size (for solid particles with a given density) to characterize the slurry and the flow conditions, and to match them with an adequate pressure loss prediction method. For each combination of flow velocity, solids concentration and particle size, a description of the most likely prevalent flow conditions and some known methods of dealing with them will be presented. Qualitative definitions of ""high"" and ""low"" magnitudes of the aforementioned parameters will be given as a general guide to the classification scheme presented in this paper."

Jan 1, 1992

By Vern Evans

Saskatchewan has historically been recognized for farming, but in 1943 while drilling for oil, potash was discovered. The initial attempt to gain access to the potash beds was unsuccessful, however, subsequent attempts were successful and today there are ten operating potash mines in Saskatchewan. In this paper we will provide a brief overview of the historical and current Potash industry in Saskatchewan.

May 1, 2011

By N. Bahrani

Knowledge of the state of stress in the Earth?s crust is very important to the safe and efficient development of underground excavations in mining and civil engineering projects. A number of methods have been developed over the past 40 years to assess the stress field in the rock mass. These range from local estimates derived from compilation of regional stress databases to back-analysis of field observations to dedicated in situ measurements. The Geomechanics Research Centre (GRC) at MIRARCO has a long history of undertaking in situ stress characterization and measurement. In this paper, the stress measurement techniques used by the GRC, including overcoring and undercoring in addition to borehole breakout back-analysis, are briefly reviewed. The limitations and application of each technique for different ground conditions and the challenges involved during the field work and in interpretation of the results are discussed. A successful stress measurement campaign is not limited to acquiring valid local measurement, but must include a careful interpretation and integration of the measurement with other geological and geotechnical context information. Based on our experience, it is suggested that all available stress indicators and data are combined and integrated with the local geological and geomechanical conditions to derive a consistent stress characterization for a given site.

Aug 1, 2013

By Marco Quirion

The Daniel-Johnson dam, formerly named Manicouagan-5 (Manic-5), is located 800 km northeast of Montreal (Quebec) in Canada. This is the largest multiple-arch concrete dam in the world consisting in 13 arches and 14 buttresses. Since its construction in 1969, various type of cracks have appeared on both downstream and upstream faces of almost all the arches of this concrete dam. As a part of the Daniel- Johnson’s dam safety assessment program, Hydro-Québec is currently performing structural analysis of the dam with advanced numerical models to better understand and predict the dam behaviour. Because the buttresses transmit all the arch loads to the rock mass, determination of the properties of the dam foundation should not be neglected in dam global safety analysis and also to insure that reliable input parameters are used in the dam numerical simulations. This paper summarizes the past and the more recent investigations of this foundation used to assess its safety and stability. Moreover, the use of rock mass classification to estimate the deformation modulus, based on empirical equations, gives values in the range of 30 to 40 GPa that are higher than expected values. Using those values in the numerical simulations for dam structural analysis gives an excellent correlation with displacements monitoring of the buttresses.

Jan 1, 2015

By A. A. Abdul-Latif, A. Sahin

"The phosphate deposit, located in the Abu Tartur plateau between the Kharga and the Dakhla Oases in the southern part of the Western Desert of Egypt, is the largest of its kind in the country. The phosphates are found in two horizons referred to as the Lower and Upper Phosphate Horizons within the Late Campanian Sibaiya Formation which belongs to the Nubia Group.This paper presents the results of a geostatistical study on the main phosphorite bed at the base of the Lower Phosphate Horizon which contains almost all the commercial reserves in the area. After semivariogram modeling for the phosphate thickness and accumulation, ordinary block kriging was employed to estimate the values of these variables in blocks of400 m by 400 m dimensions. The kriging results, which are presented in the form of contour maps, can be of considerable use in both future exploration and exploitation of the deposit. The grade-tonnage relationship based on the grade estimates derived from the corresponding thickness and accumulation estimates indicates the existence of 453.9 x 105 tonnes of phosphate above a cut-off grade of 18% P2O5. The mean grade of this tonnage has been estimated to be 25.77% P205"

Jan 1, 1990

By A. C. Atenas

The majority of refineries that operate with traditional starting sheet technology ?starting sheet- uses a relatively low current density of 250 A/m2. Industrial tests at high current density with conventional technology were carried out in Refinery of Potrerillos, getting satisfactory results that are similar the results obtained with permanent cathode technology. The series of copper refining electrolyses electrolysis trials were carried out between 300 to 325 A/m2. Electrolysis conditions, in accordance with industrial practice, were kept constant in all sets of experiments and were as follows; 45 g/L Cu 2+, 210 g/L H2SO4, 62 °C, electrolyte circulation of 14-18 L/min. The same Dosing dosing of Additives additives used in permanent cathode technology was required in these tests. In general, only not importantminor operational modifications were necessary in comparison to normal practice in the Refinery to assure the good results. Different quality of starting sheet and anodes were examined. The test included starting sheets from smelter and laminated process. Results indicate that the charge physical quality of the electrodes and the control of the process during the two first days of operation are the keys to get the best results.

Jan 1, 2007

By Mark Stephenson, Paul Henharen

"The objective in the mineral processing of primary ores is to liberate and effectively recover each individual economically viable diamond with minimal reduction in its potential value.There are three distinctive phases in diamond processing:Feed PreparationWhere the diamonds are liberated and waste material finer than the economically selected cut-off size is rejected. In this section we will discuss the various techniques utilised worldwide to effect feed preparation.Primary ProcessingWhere the diamonds are recovered into a high grade concentrate suitable for the more expensive and selective final recovery process. In this section we will discuss the development of primary processing from jigs and pans to the more current techniques utilised worldwide.Final RecoveryWhere there is selective rejection of waste particles until only diamonds remain. The diamonds may then be acidised prior to packing and marketing.Within these distinct phases a variety of unit processes have been utilised and this paper will discuss their relative merits, limitations and suitability in respect to the various stages of diamond project development from prospecting through to production.Basic capital and operating costs are compared for the autogenous milling route developed in the CIS and the crushing and scrubbing route utilised in the west."

Jan 1, 1994

By R. G. Gillies, C. A. Shook, W. H. W. Husband

"The current state of knowledge concerning pipeline transport of coal in water slurry form is summarized for the four categories: coal-water fuels, conventional fine coal slurries, coarse coals and stabilized mixtures of coarse and fine particles. Surface chemistry is of dominant importance for coal-water fuels and considerable progress in understanding the role of surfactants has been achieved in recent years. Little generalized research on the flow of conventional fine coal slurries has been done in the past 17years, although innumerable conceptual designs and feasibility studies have been undertaken. Coarse coal slurries are fairly well understood but the model which explains their flow requires more data to be established fully. Stabilized flow mixtures should probably obey the same model as coarse coal slurries but experimental results for stabilized mixtures have not yet been incorporated in a comprehensive theory.IntroductionPipeline transportation of coal in a water vehicle has been employed for many years in coal washeries. It has been used less frequently in hydraulic mining and thermal power station fuel supply systems. The suitability of coal for pipeline transport arises from its moderate specific gravity relative to the carrier fluid and the fact that throughputs are often large and steady over long periods of time."

Jan 1, 1990