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By Smortchevskyk N. J.

THIS paper describes the electrical features of the locomotive now (August, 1962) under construction for Craigmont Mines. Intended for non-specialists, it avoids details of design and calculations interesting to electricians only. The paper is divided into three sections. The first deals very briefly with the mine layout and with operating conditions -existing and expected. Reference is made to economic considerations leading to the selection of the type and size of locomotive, as well as to traction diagrams and the calculations. This material is not included in the paper because of its length and because it does not represent anything new. The second section deals with engineering and economic considerations and shows, in some detail, why the A.C. system was chosen. The third section describes the basic components of the locomotive, including the voltage regulator, the rectifiers, the control arrangement and the filter, and deals with considerations affecting the selection of their rating and design. A concluding sub-section describes, very briefly, the track and trolley details and the power distribution switchgear.

Jan 1, 1963

By E. G. Charlesworth, M. J. Robertson

"Abstract - Gold mineralization in the Main Reef Complex at Sheba Gold Mine is hosted within shear zones in a sequence of shales and greywackes of the Fig Tree Group. Competency contrasts between these rocks and a steeply dipping chert unit provided a locus for the development of right lateral steeply dipping shear zones. A set of flatter dipping shear fractures crosscut these zones with their intersections defining a system of en échelon ore shoots.Mineralization is both of vein type and disseminated strata-controlled replacement type. The latter occurs mainly within the wall rocks to the shear zones. Arsenopyrite and pyrite are the major sulfides, with arsenopyrite being confined largely to greywacke beds and pyrite to the more iron-rich shale units. Gold was introduced, together with minor sphalerite, pyrrhotite, chalcopyrite and early arsenopyrite, toward the end stages of a first pyrite phase. The mineralizing fluids were introduced along dilated cleavage planes and, emanating from these, produced a series of replacement fronts. Mineralization was syntectonic to late tectonic and occurred under conditions of progressive deformation, resulting in sulfides which are concentrated in the hinges of shear-related folds and semi­ massive sulfides within tension fractures which are folded, attenuated and fractured .An analysis of the structures shows a sequence of events in which an initial ductile simple-shear event with a steep sense of movement was succeeded by a more brittle strike-slip event. Mineralization is temporally related to the latter. This evolution in structural style was probably related to reactivation of the Sheba Fault as a transcurrent fault during emplacement of large granitoid bodies."

Jan 1, 1994

By G. Forté, R. Girard

The Alcan Bayer Process Experimental Centre (BEC) is an essential development tool for the Bauxite & Alumina researchers at the Alcan Arvida Research and Development Centre in Jonquiere, Quebec. Between the laboratory tests and the industrial prototypes or the industrial applications, the BEC is a key element for technology transfers. The Bayer process is the extraction of aluminium oxide (or alumina) from the bauxite ore. The Bayer Experimental Centre's history and flowsheet are presented. The major pieces of equipment are described. Safety and design considerations are presented. Finally, examples of applications, double digestion and pressure decantation, are briefly described.

Jan 1, 2004

By Y. Chengxian, F. Yaorong, Xinzhe. L.

Many factors about the HIC (hydrogen-induced cracking) resistance of pipelines are discussed in this paper. The main factors that influence the ability of HIC are environmental and material factors. The chemical compositions, non-metal inclusions and microstructure are discussed in detail, while a group of tests on HIC resistance are done according to varying C, S, Mn and P contents in pipeline steels, different experiment time and different strength to the coupon. It is concluded that decreasing the amount of C and S can obtain good HIC resistance; the test time has an effect on the different microstructure of X70; microstructure is the most sensitive factor for the initiation processes of HIC.

Jan 1, 2005

By Derek Perkins

"Brenda Mines Ltd. operates an open pit copper and molybdenum mine located in south central British Columbia. The main economic mineralization is chalcopyrite and molybdenite. Pyrite, galena and sphalerite are also present in varying quantities. The mineralization is present in small veins and fractures in a porphyritic quartz diorite host rock.The mill processes approximately 30,000 tonnes of ore daily. The ore is crushed in three stages and then ground in conventional rod mill - ball mill circuits with cyclone classification. The cyclone overflow is fed to the bulk flotation circuit as a pulp with a density of 50% solids. The particle size distribution is approximately 35% plus 65 mesh. Bulk rougher and cleaning flotation produce a concentrate grading approximately 20% copper and 4% molybdenum. This concentrate is fed to the separation circuit, where the copper is depressed with sodium hydrosulphide and the molybdenum is floated. These products are further ground and then upgraded by column flotation. The molybdenum concentrate is pumped to the leach plant to reduce concentration of lead and copper. It is then washed, filtered, dried and packed for shipment to Europe. The copper concentrate is filtered, dried and subsequently shipped to Japan.Prior to November 1977, the mill flotation control was carried out by the assay laboratory using a Philips PW 1540 sequential x-ray spectrograph. The assay set consisted of twelve samples, analysed on a two hourly basis for copper, molybdenum, lead, iron and silica.In order to provide elemental composition information on a much shorter sampling interval and to produce speedier control analysis for automating process control, an Applied Research Laboratories PCXQ on stream analyser was purchased. The installation of this analyser, reduced the turnaround time of the control analyses from (2) hours to (20) minutes. At Brenda, the following assays are used in the mill control strategies."

Jan 1, 1989

By N. Bahrani

Photogrammetry surveys were used to document a footwall slab failure that occurred at a surface coal mine located on the eastern slope of the Rocky Mountains. Photographs taken before and after the failure provided the pre- and post-failure geometry of the slope and the failed slab. A 2D finite element model was constructed using slope profiles. The model contained joint elements that represented the bedding surface upon which the slab slid and the model was used to analyze the footwall slope. The in situ stresses, rock properties and the bedding surface shear strength and stiffness properties are discussed. The process of mining out a valley and exposing a highwall was modelled. As expected, elastic valley rebound occurred in the model, but shear stress and shear displacement reversals along the slip surface were also observed. The modelling results provided new insight into shear strength degradation that occurs when the pit floor approaches and then passes a specific point in the highwall.

Jan 1, 2009

The most expensive unit operation in the beneficiation of ores is grinding. The correct design of the grinding circuit is crucial to prevent unnecessary use of energy. Proper design and evaluation of SAG grinding circuits require the specific grinding energy, which is determined experimentally. The most common tests in SAG grinding are the Drop Weight Test, from the Julius Kruttschnitt Mineral Research Center (JKMRC) in Australia, and the SAG Power Index, from MinnovEX Technologies in Canada. The application of these tests to the same ore sample commonly produces different results. The work reported here aims at comparing the application of these two tests in the determination of the specific grinding energy for sulfide copper ores from Sequeirinho and Sossego deposits, Sossego Project, Companhia Vale do Rio Doce - CVRD, in Para state, Brazil.

Jan 1, 2007

By H. L. Noblitt, Pauline Moyd, Louis Moyd

The deposit, which forms a ridge -adjacent to the York river, in Mont-eagle township, is held by Monteagle Minerals Limited, of Toronto. The ore is in a Precambrian gneiss which is composed of nepheline, scapolite, andesine and microcline feldspars, muscovite and biotite micas, and -corundum. The major orebody is tabular and is exposed for 1,200 feet along the crest of the ridge. It aver-ages about 90 feet in thickness, dips at about 70°, and was intersected by drilling at a vertical depth of 600 feet. The deposit was prospected for corundum in the early 1900's. Recent exploration was undertaken to deter-mine its potential as a source of high-alumina ceramic material, with by-product corundum and white mica. The program included prospecting, mapping, trenching, diamond drilling, bulk sampling, beneficiation research, a large-scale beneficiation test, product evaluation, market investigations, and plant design. Reserves, to a depth of about 300 feet, are estimated at about 3 million tons.

Jan 1, 1962

By B. Erdem, N. Çelebi

An important problem associated with tandem dragline systems is that of matching the productive capability of individual draglines in the combination. In this paper, a dependence mechanism among draglines in a tandem system is described, and possible consequential problems in a poorly-matched system are defined. The rate of linear advance and the cost of stripping are determined as two major indications for an efficient operation. The proposed decision criteria and the underlying mechanism to select a synchronous couple are introduced and used in simulating tandem dragline systems. The developed model is tested on a hypothetical strip mine where pullback stripping is applied with a tandem dragline system.

Jan 1, 1999

By D. J. Charlton

"IntroductionMaintenance is a business, which to be successful, requires good management, systems and reporting. The prime objective of the maintenance management group, be they large or small, must be to anticipate and prevent interruptions in operations by keeping equipment in good mechanical condition. This objective should be carried out at minimum cost consistent with maximum productiveness.The objective of this chapter is to give an insight into the various aspects of maintenance management that must be considered to effectively and efficiently operate a mill complex. The degree to which the maintenance sub-systems are developed in an operating mill will be determined by the size of the mill and the needs of the operation.The criterion of the management system used is that the system serve the operation and not vice versa. The systems presented should be considered as tools and, as with all tools, they must be sharpened and replaced as the need arises or as more effective tools become available.To understand what is involved in maintenance management, it is worthwhile to consider a systems approach to analyzing management problems. This approach was developed by J.A.B. Rae while reviewing maintenance management systems for Cominco Ltd.A very simple system involving managing results and objectives is shown diagrammatically in Figure 1.The systems approach to organizational development involves four basic elements: an objective, a result, an activity and feedback. In the analysis, the activity element is broken down into individual actions that people could be held responsible for. If we introduce the action of operating into the diagram of Figure l, we arrive diagrammatically in Figure 2."

Jan 1, 1989

By W. E. Cockfield

This paper is not intended as an original contribution to this subject, but rather as a review of the main theories which are held with regard to placer deposits, with, of course, particular reference to the placers of British Columbia. The present interest in gold mining has, however, brought the subject of placers to the fore, and possibly a brief outline of the geology of such deposits will serve as a basis for discussion on the subject. In Canada, the most valuable of our placers are deposits of gold, and consequently the discussion will centre largely on placer-gold deposits. The same principles apply, of course, to placer deposits of other metals. The Origin of Placer Deposits As a starting point, the idea which is prevailingly held is that placer or alluvial gold is detrital in origin, that is to say, the gold originally existed in veins, lodes, or disseminations in the country rock of the regions in which the placer deposits are now found, and that, through the various erosive forces of nature, it was liberated from those veins or lodes and concentrated in the form in which we now find it. 1 have not time to go thoroughly into the proof of this, but the lines of evidence are many. If we take the Cariboo district as a typical example, Johnston and Uglow(l) have shown, first of all, that the placer and vein gold are identical in character. Crystals occur both in the placers and in the lodes, but the crystals in the placers are nearly always slightly worn, indicating transportation.

Jan 1, 1932

By Matej Petružálek, Tomáš Svitek, Tomáš Lokajícek

"Migmatite from the Skalka region (Czech Republic) was chosen as the experimental rock material. It has macroscopically visible plane parallel structure (foliation). The foliation was caused mainly by biotite grains arrangement. The cylindrical samples of migmatite with subhorizontal, subvertical and oblique foliation were uniaxially loaded up to the failure. Network of 8 broad band sensors was employed for acoustic emission monitoring and ultrasonic sounding. A grid search method with anisotropic velocity model was used for AE hypocenters localization. The source types of successfully localized events were determined from the average first arrival amplitude. Structural anisotropy of tested rock material caused the anisotropy of its mechanical properties (peak strength, Young’s modulus) as well as a different way of fracturing process in dependence on the angle between axial stress and foliation plane. The combination of splitting, shearing and sliding was found to control the fracturing of sample with subhorizontal foliation. The shearing and sliding was dominant in fracturing of samples with oblique foliation. With greater dip of foliation, the role of sliding increased at the expense of shearing. Due to the favorably oriented system of microcracks already present, the shearing and splitting was at the same level during fracturing of the sample with subvertical foliation before nucleation began.INTRODUCTIONThe process of failure of low porosity rocks depends on their mechanical properties and actual stress and temperature condition. At the low pressure and low temperature, the most common way is brittle failure, which is a progressive process requiring the initiation, growth and coalescence of cracks (Lockner, 1993). Stress strain behavior of low porosity crystalline rocks, during the laboratory compression experiments, is divided into four characteristic stages: crack closure, elastic region, stable crack growth and unstable crack growth which leads to the brittle failure, Brace et al. (1966) , Bieniawski (1967), Lajtai (1974), Cai et al. (2004), Nicksiar and Martin, 2012 and 2013.The fracturing process of stressed rock begins with the crack initiation (sci), which for low porosity rocks occurs approximately at 40-50% of peak strength (sp) (Cai et al., 2004; Nicksiar and Martin, 2013). After the sci, the dilatancy begins and stable crack growth follows up to the crack damage threshold (scd), which is approximately at 80% of sp (Cai et al., 2004). After crossing the crack damage level, there is an unstable crack growth accompanied with nucleation of fault plane (sn) at 97-100% of sp. (Rao et al., 2011). The stress drop accompanied with formation of macro scale shear failure plane follows after peak stress is crossed."

Jan 1, 2015

By F. Sorenson, P. A. Castellarini, F. Garbarino, M. N. Garcia

"Recently, significant efforts to improve productivity from the tight intervals of the Mulichinco Formation within the Sierra Chata Field in the Neuquén Basin have been ongoing. Because conventional high quality reservoirs were being developed in this field, a proper reservoir understanding and completion approach was applied. After developing these high permeability reservoirs, the operator began evaluating the tight intervals and new areas within the field, but a completely different approach was necessary to achieve motivating production improvement.An extensive study to help enhance reservoir understanding and identify key factors controlling productivity of these tight intervals (which tend to be in the range of 5 µD) has been ongoing. Some of the issues discussed in this study are 1) petrophysical review, 2) rock properties calibration, 3) geomechanics understanding, 4) faulting and micro faulting/lineaments description, 5) stimulation and completions review and, 6) understanding key production drivers.As in many other tight reservoir projects, a considerable area of the reservoir must be effectively stimulated during the hydraulic fracturing process to achieve economic productivity. Two critical issues hinder these objectives. First, the low permeability in addition to a pore pressure close to or even lower than hydrostatic are critical characteristics when attempting to flow back the well and clean up fractures. Second, very high horizontal stress anisotropy resulting from a strike slip stress regime promotes the generation of simple planar bi-wing fractures. It is well-known that this fracture geometry will contact much less reservoir area compared to more complex fractures, as the operator would normally intend to create at very low permeability reservoirs.This paper discusses these issues and how they were addressed. A pilot drilling and completion program was initiated during 2012 to validate this study. Key factors include well location relative to formation unconformities, their orientation relative to the far field principal stresses, hydraulic fractures generated, and overall completion design."

Jan 1, 2015

By C. J. K. Purdy, H. E. Jamieson

"The comprehensive assessment of the environmental impacts of mining rare earth element (REE) deposits depends on a sound knowledge of the mobility of REEs in low-temperature aqueous environments. Temperature, pH and water chemistry are important factors controlling the aqueous mobility of REEs, while REEs are known to readily form complexes with both inorganic and organic ligands, and it has been shown that sorption and colloid formation may play an important part in dictating REE transport in the low temperature weathering environment. Ore and host rock mineralogy is also a key factor controlling the extent to which REEs are leached from mine waste. INTRODUCTIONThe aqueous mobility of rare earth elements (REEs) has commonly been explored in the past due to their potential application as tracers of geochemical processes in aqueous systems. REE mobility in low-temperature solutions has been shown to be dependent on the pH, temperature, ionic strength, and solution chemistry. For example, the aqueous transport of REEs can be modified by complexation with organic and inorganic ligands (Johannesson & Zhou, 1999; Klungness & Byrne, 2000; Luo & Byrne, 2004; Schijf & Byrne, 2004; Tang & Johannesson, 2010; Wood, 1990, 1993), or through sorption to suspended particles and colloids (Bau, 1999; Quinn, Byrne, & Schijf, 2004, 2006a, 2006b, 2007; Sholkovitz, 1995). Here we review the coordination chemistry, sorption behaviour and potential colloid association of REEs with respect to low temperature aquatic settings.RARE EARTH ELEMENT CHEMISTRYREEs include lanthanum to lutetium of Group IIIA in the periodic table. All share very similar chemical and physical properties. Often included in REE studies is another Group IIIA element, yttrium owing to its similar properties, and occasionally scandium, although its considerably smaller ionic radius makes for different properties and will not be discussed further here. The REEs are often subdivided into the light REEs (LREE), La to Sm, and the heavy REEs (HREE), Eu to Lu, which also usually include Y (hence are often referred to as YREE). The REE may be subdivided further into the LREEs, middle REEs (MREEs), and HREEs, in which case each classification includes La-Nd, Pm to Ho, and Er to Lu as well as Y, respectively, although definitions vary throughout the literature."

Jan 1, 2012

By Lindsay A. Robertson

The long term management of acid generating tailings at mine closure is a common issue, however, management of ARD is significantly impacted by local conditions, including climate. Acid generating tailings, over time, will produce acid rock drainage (ARD) if left exposed to water and air, which both contribute to the sulphide oxidation process. The long term closure of tailings storage areas is a concern from both environmental and engineering perspectives, with long term acid generation and dam stability the main risks. Several approaches can be taken to minimize ARD from tailings facilities using cover systems. Three tailings facility cover case histories, in areas of net positive water balances, were investigated using unsaturated flow modelling software to determine the long term potential for limiting ARD by increasing saturation of the tailings and decreasing oxygen ingress. Each case study demonstrates the importance of integrating the tailings dam engineering into tailings cover closure design. Model predictions are compared to measured saturation levels to assess the accuracy of the calculations.

May 1, 2011

By J E. Curfman

This paper deals with using track-type and rubber-tired machines in the ripping and handling of overburden and ores. The techniques and proper attachments pertaining to the ripping of materials are covered in some detail. Production and relative costs of ripping, as against other methods, are covered in cases pertaining to the mining industry. The use of the refraction seismograph in predetermining the rippability of materials, including a chart relat-ing velocity to rippability, is covered. This operates on the principle that sound waves travel through subsurface materials at different velocities, depending upon the degree of consolidation of the material. It is known that the same factors that affect consolidation also affect rippability. Proper equipping of the tractor to insure maximum efficiency is also covered in some detail. Introduction T HE idea of loosening consolidated materials prior to further handling and processing is probably as old as man. The purpose of ripping is to provide fragmentation of rock and loosening of consolidated materials.

Jan 1, 1965

By A. K. Debnath

The water resource is key to survival of the mankind and this resource is now becoming critical in many parts of globe including India. As per an assessment of Central Ground Water Board (CGWB) of India, a huge shortfall of about 58 billion m3 of water is anticipated by the year 2050. In order to counter this shortfall, there is thrust from Government of India to adopt water conservation measures. National Environment Policy, 2006 of Government of India also stresses upon the need to take up water conservation measures for water security of the country. The coal mines in India provide an excellent opportunity to take up water conservations measures therein. The mine water is not acidic unlike western countries and it conforms to the prescribed regulatory standards. This nature?s gift is utilized in Coal India Limited by allowing mine voids to get filled with mine water. The net recharge potential of the opencast mining area is found to be about 5% in comparison to 2% in non-mining area offering good prospects for ground water recharge. The seasonal rainwater is also diverted into mine voids left at the end of mining operations which act as huge reservoirs/ pit lakes for storage of the water. They also serve as surface water bodies for recharging of water table in the surrounding areas. The area and space left from where coal has been extracted completely in underground mines and will not be entered by any man or machinery after the extraction, called goaf, are also potential source of water conservation. These additional water resources created are being utilized for meeting the industrial, domestic, irrigation and other requirements of the projects and local communities eliminating the need to tap other fresh water resources including ground water. Presently, 75% of the water demand of the coal mining project is being met from the water stored in the mine pits. In future, CIL is likely to create about 3.3 billion m3 of water resource, on an average, in its opencast mines alone. In the mine closure plan of opencast mines, the last cut is proposed to be developed into water body for recharge of ground water and creating additional water resources. A clean potential source of potable water is thus developed after mine closure. This will ensure water security of the country.

Aug 1, 2013

By K. G. Markkola

Since 2005, Compafifa Contractual Minera Candelaria (CCMC) has defined various strategies which aim to optimize the usage of the available energy in each of the SAG grinding circuit modules (SABC-A configuration). For this purpose, the use of larger size balls along with operating with an optimum balls/load ratio has been implemented. Additionally, in the ball mills, the amount of balls in relation to the equipment's usable diameter has been optimized. In the pebble crushing circuit, the percentage of material passing 12 mm (112 in) product has been increased by 15% by: (1) modifying the crusher mantle profile, (2) implementing a strategy for maximizing the power in each crusher, (3) using continuous improvement tools (Lean - Six Sigma), (4) redesigning SAG mills discharge grates, and (5) changing discharge grates in order to control the crusher feed size distribution profile. All these activities have improved plant throughput by 1,000 t/d with no significant capital investment. As part of the energy consumption optimization study, we have considered determining the optimum operational rate of each SAG mill, in relation to the mill liner life and also the improving the control strategy in conventional grinding.

Jan 1, 2007

By Jean-Francois Magnan

"The old conventional process to produce lithium raw material dates from 1954 (CA patent #504477A). This process produces low purity lithium carbonate (Li2CO3) only. To obtain battery-grade carbonate, another polishing process is needed. To further obtain lithium hydroxide, another chemical conversion process is needed. That is why historically, the value of lithium hydroxide has always been higher than that of the lithium carbonate precursor. With the old conventional process, the low quality lithium carbonate is precipitated from a lithium sulfate solution (Li2SO4) by adding soda ash (sodium carbonate and its impurities). The resulting reaction produces significant quantities of sodium sulfate (salt cake) as a by-product with amounts larger than the impure Li2CO3 recovered with part of the soda impurities. When this conventional process was invented, the salt cake by-product was not an issue: it was discarded in a river near the plant. This practice cannot be done today in North America. While looking to find a solution for salt cake, electrolytic salt splitting of Na2SO4 into NaOH and dilute sulfuric acid appears as a technically feasible solution to get a rid of the salt cake. However, the sodium sulfate salt splitting process has difficulties to economically compete with the chlor-alkali process, which produces millions of tons of NaOH from sodium chloride (NaCl) every year.In contrast, the process developed by Nemaska to directly produce LiOH by Li2SO4 salt splitting not only solves the environmental problems related to the conventional process to produce lithium carbonate raw material, it also produces very high purity lithium hydroxide monohydrate directly at very competitive OPEX cost in comparison with industry peers (Figure 1). It also drastically reduces the amount of reagent and the direct greenhouse gas emissions."

Jan 1, 2016

By C. Moreland

Fluidized low-temperature carbonization of coal, a recent development, offers a possibility of reducing fuel costs of coal-burning electric ?generating plants. The Research Council of Alberta have built a pilot plant and are conducting a programme to -develop a carbomzation plant for Alberta sub-bituminous coals which will produce char suitable for use as a .boiler fuel, and tar of a potentially high value as a ?chemical raw material. The economies of the process as a whole, and the value of the tar, have yet to be assessed.

Jan 1, 1958