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"In the first half of 1990, Cambior earned $1104 million, or $0.37 per share, on revenues of$66.4 million. The company's strong cash position, attained late in 1989 and in the beginning of1990 through the exercise of warrants, put working capital at $83.8 million as of June 30, 1990. Long-term debt was reduced by over $10 million during the weak gold market, leaving the company with a debt to equity ratio of only 0.03. Production for the six first months of 1990 was 107 720 oz. Au, an increaseof24% over the corresponding period in 1989.Financial Profile/Results and Corporate Financial StrategiesTotal revenue for the 1989 fiscal year was $116,883,000 compared to $109,848,000 for 1988. The 1989 results achieved despite a lower average gold price, resulted from a higher level of commercial gold production and a 115% increase in investment income over 1988. Investment income rose to $3,568,000 in 1989 due to higher levels of cash assets.Cambior's mine operating costs increased 19% to $68,561,000 in 1989 from $57,472,000 in 1988. This increase resulted from rising operating costs at the Doyon Mine ($250/oz to $274/oz) due to the shift from open pit to underground operations, as well as from the start -up of three new mines with relatively higher costs. These costs have reached a stable level that should be maintained for the next few years.In 1989, net exploration expenses were $6,838,000, down 31070 from 1988, partially due to the Canadian tax reforms introduced since 1987. Depreciation and depletion grew by $1,432,000 in 1989, reflecting a higher volume of commercial production from the Pierre Beauchemin, Lucien C. Beliveau and Chimo mines.Net earnings for 1989 amounted to $17,661,000 or $0.73 per share compared to $17,438,000 or $0.74 per share in 1988.Cambior has an exceptionally liquid and strong balance sheet. As at December 31, 1989, net working capital stood at $85.6 million, with a total assets base of $338.6 million. With a long-term debt (including gold loans) of $21.5 million and shareholders' equity of $277.2 million, Cambior has a debt to equity ratio of 8%. All but about $100,000 of long-term debt is in the form of gold loans.The total market value for Cambior's stock as at September 10, 1990, stands at $420million, based on recent stock market prices. Cambior's stock and warrants are traded on the Montreal and Toronto Stock Exchange."

Jan 1, 1990

By Nn Li

Energy consumption in commercial buildings has been increasing rapidly in the past decade. The knowledge of future energy consumption can bring significant value to commercial building energy management. For example, prediction of energy consumption decomposition helps analyze the energy consumption patterns and efficiencies as well as waste, and identify the prime targets for energy conservation. Moreover, prediction of temporal energy consumption enables building managers to plan out the energy usage over time, shift energy usage to off-peak periods, and make more effective energy purchase plans. This paper proposes a novel model for predicting heating, ventilation and air conditioning (HVAC) energy consumption in commercial buildings. The model simulates energy behaviors of HVAC systems in commercial buildings, and interacts with a multiagent systems (MAS) based framework for energy consumption prediction. Prediction is done on a daily, weekly and monthly basis. Ground truth energy consumption data is collected from a test bed office building over 267 consecutive days, and is compared to predicted energy consumption for the same period. Results show that the prediction can match 92.6 to 98.2% of total HVAC energy consumption with coefficient of variation of the root mean square error (CV-RMSE) values of 7.8 to 22.2%. Ventilation energy consumption can be predicted at high accuracies (over 99%) and low variations (CV-RMSE values of 3.1 to 16.3%), while cooling energy consumption accounts for majority of inaccuracies and variations in total energy consumption prediction.

Aug 1, 2013

The dynamic breakage process of rocks by the impact of a hydraulic hammer is more complex than one normally assumes. It is even more difficult when one has to conduct the breakage under water. In such cases one does not know exactly what the surface topography and composition are at the bottom of the sea or river and, hence, it is more difficult to select the best position of the hammer before starting the hammering. Typically, an industrial hammer has a diameter of about 250 mm, a length of about 1.25 to 1.75 m and a mass of several tons. The hammer frequency can be up to 50 impacts per minute. The general principles of rock hammering can be easily summarized, but this knowledge is not sufficient to adapt adequately the method for less common rock conditions (e.g. less brittle rock, presence of vertical and subvertical fractures, etc.). That is the reason why we initiated a research project, whereby a scale model has been developed to conduct experiments in the laboratory and whereby discrete element simulations are being conducted. Both aim at a better understanding of the basic mechanisms of rock hammering. The scaled experimental model allows varying the impact energy and the static weight independently. Within the experiment, the hammer is in contact with the rock specimen under a certain confining pressure and with a certain contact pressure due to the static weight. A weight falls on the hammer, creating the dynamic action or impact; the height over which the weight falls can be varied. The penetration is recorded after each impact. After a certain penetration the test is stopped and the internal crack patterns are described. Some simulations have been conducted, allowing the modeling of individual fracture initiation and growth during the penetration of the hammer by either a constant displacement rate (using the UDEC-code) or by introducing the dynamic process (using the PFC-code). Some of the observed features in the laboratory experiments can be visualized in the simulations. However, further research is needed to allow the simulations being an adequate tool to well understand the dynamic process in laboratory experiments, as well as the in-situ behavior.

Aug 1, 2013

By Y. Wang, J. D. Miller, C. L. Lin, Virginia Tech

Conventional flotation machines are typically limited to a particle topsize of 150-200 microns due to inherent constraints created by the pulp and froth phases. To overcome these limitations, a novel fluidized-bed flotation system called the HydroFloatTM Separator has been developed specifically for the purpose of floating coarse particles containing only small amounts of exposed hydrophobic minerals. Over the last decade, this technology has been successfully applied to industrial minerals with several full-scale units installed to recover particles up to and exceeding 3,000 microns diameter. More recently, sulfidebased test work has shown that this novel device is also capable of recovering metalliferous values at a grind size that is much coarser than currently used in industrial concentrators. In the current study, high resolution X-ray microtomography (HRXMT) was used to experimentally compare the degree of exposed grain surface area necessary to recover coarse particles using the HydroFloatTM technology to that attainable using a traditional mechanical flotation cell. The data indicate that exposed grain surface area is a critical factor for coarse particle flotation. For the gold-bearing sulfide ore examined in this study, the HRXMT data suggest that near complete recoveries of coarse (850x500 µm) multiphase particles containing as little as 1% exposed grain surface area were realistically attainable using the HydroFloatTM technology. As such, this new technology may offer a unique opportunity for increasing concentrator capacity by increasing the primary grind size needed for rougher/scavenger separations.

Jan 1, 2016

By Rakesh Kumar, Rajabrahma K., A. K. Verma, V. Mukesh

"In this study, laboratory investigation as well as numerical investigation is carried out to ascertain the transition from one mode to another for Semi-circular bend setup. Laboratory investigation is carried by varying the span length (s/2R); crack length (a/R); notch angle (a); and notch thickness (t). The specimen consists of cement, sand and water mixture in a ratio of 1:1:0.5 by weight and are prepared as per the ISRM standards (2014). Tests are conducted by a servo controlled universal testing machine at a strain rate of 0.2 mm/ min. The results are collected in terms of failure load, crack mouth opening displacement (CMOD) and images of crack initiation and propagation.Image analysis of laboratory tested samples shows that crack initiates at the notch tip when the notch inclination angle is 0°. As the notch angle increases (i.e. 30° and 60°) the fracture begins to initiate behind the notch tip. The direction of crack propagation in front and back side of the sample is same for notch inclination angle is 0° whereas it differs more and more as crack inclination increases. The transition represents the change in mode of failure from mode I (0°), mode II (30°) and mixed mode I/II fracture (60°).Finite element method used to find the transition based on MTS failure criterion. The inclination of notch is varied like 40, 42, 44, 45, and 50 deg and FEM analysis shows that the transition from mode-I to Mode-II take place at 49 deg. The same procedure can be extended to find the transition from mode-II to mode-III."

Jan 1, 2015

By F J. Pearce

The Steel Company of Canada, utilizing the S-L process, has produced partially and highly reduced pellets for use in the blast furnace. Experimental blast furnace tests, using reduced pellet burdens, have been carried out. The changes in production rate, fuel rate and general performance of both the S-L and the blast furnace processes are indicated. Introduction T HE ore burdens for a blast furnace may be improved in two ways: chemically, by concentrating the ore to a high degree of purity; and physically, by agglomerating or closely sizing the ore particles. Today, many b1ast furnaces are charged with closely sized agglomerates, some of which contain upwards of 66 per cent iron. The further improvement of these burdens by chemical concentration may, in many instances, be uneconomic due to the large losses of iron that occur during processing. Assuming that it would be possible to reject all of the gangue minerals, the maximum level of concentration of iron in the hematitic ores would be only about 70 per cent.

Jan 1, 1964

Uranium mining remains controversial in many parts of the world, especially in a post-Fukushima context, and often in areas with significant uranium resources. Although nuclear proponents point to the relatively low carbon intensity of nuclear power compared to fossil fuels, opponents argue that this will be eroded in the future as ore grades decline and energy and greenhouse gas emissions (GGEs) intensity increases as a result. Invariably both sides fail to make use of the increasingly available data reported by existing uranium mines through sustainability reporting ? allowing a comprehensive assessment of recent trends in the energy and GGEs intensity of uranium production, as well as combining this with reported mineral resources to allow more comprehensive modelling of future energy and GGEs intensity. In this study, detailed data is reported for numerous uranium mines around the world, including production, energy and GGEs intensity and reported mineral resources. An important aspect included ? arguably unique and never before published ? is the relationship between ore grade and recovery, which is crucial in future projections of uranium mining. Overall, the paper shows the importance of continuing to improve reporting by the uranium sector as well as the ability to analyse key trends and future projections in energy and GGEs intensity of uranium production.

Aug 1, 2013

By S. Orangi

A representative sample of ramming paste from a peripheral seam in an aluminium electrolysis cell was taken in order to develop a process to fabricate ramming paste samples in the laboratory. To this end, paste material was compacted in multilayers in a mould designed to be representative of peripheral seams in Alcoa's smelters. The density distribution in the representative sample was measured ranging from 1.51-1.76 g/cm3. The density range obtained by the proposed methodology in laboratory is 1.47-1.77 g/cm3. The results demonstrate that the proposed fabrication method adequately duplicates paste density from the cell for both one and two layer compaction. Finally, preliminary results related to the compressive strength and Young's modulus of laboratory samples were obtained at various temperatures and are presented in this paper.

Jan 1, 2011

By E. Nejati, S. Khoshkooei, V. Firouzdor, M. Akbari, F. Khomamizadeh

In this study the effects of Si content on mechanical and thermal fatigue properties of Al-Si casting alloys were investigated. Repeated heating and cooling cycles were applied on the samples at 230°C to develop thermal fatigue cracks. Crack growth mechanisms and microstructural influences were investigated by optical and scanning electron microscopy. Thermal fatigue behaviors were improved successively by increasing of silicon content up to 7wt%. However, addition of more than 9wt% silicon decreased the thermal shock resistance of the alloy. Silicon contents of about 9wt% presented the best mechanical and thermal fatigue resistance in the alloy.

Jan 1, 2006

By Jacek Paraszczak

Possibility to move human workers away from dangerous places ?enhanced safety and improved working environment; ? Increase of actual operational time: ? Less losses due to shift changes, regulatory breaks, blasting periods, ventilation after blasting, etc.; ? Possibility to work in extremely dangerous conditions where man-operated machine could not be used (for example: ST-14 loader in backfilling operations in the Kemimine, following roof collapse). Reduction of the production cost through: ? Lower maintenance cost (less damage due to operator?s mistakes and no machine abuse); ? Higher productivity and effectiveness of the equipment (less machines to meet production targets, less operators required, lesser maintenance cost...). ? Although personnel health and safety are key drivers behind autonomous operation of mobile equipment in U/G mines, with significant capital and operation costs one expects to achieve: ? Productivity higher, or at least equal to that offered by man-operated equipment and systems; ? Lower production cost. Therefore, high effectiveness of the autonomous equipment is crucial to succeed.

May 1, 2010

By R. O. Burt

The original flowsheet of the TANCO mill consisted of a simple two-stage gravity circuit for the recovery of the tantalum concentrates. With decreasing grade and grain size of the tantalum minerals, considerable modifications to the circuit have been required. This paper discusses the various recent improvements carried out 011 all stages of the flowsheet, which have resulted in a 10% increase in recovery. Future improvements, including on stream analysis, and the possibility of tantalum flotation , are also discussed.

Jan 1, 1979

By L. J. Bryson, C. A. Biley

"Anglo American Platinum’s Rustenburg Base Metals Refiners (RBMR) produces Ni and Cu cathode from slow cooled converter matte after Platinum Group Metals (PGMs) are magnetically separated for further processing. In 2010, execution of the RBMR expansion project was commenced to increase the production capacity to 33 ktpa Ni. The expansion, which is currently still in a ramp-up stage, brought about several fundamental changes to the circuit chemistry, including the installation of a dedicated Pressure Iron Removal (PIR) autoclave. This provided an independent outlet for iron from the refinery, which previously deported to the residue from the leach circuit and was toll refined. At the same time as changes in the circuit associated with the RBMR expansion were being made, the plant experienced a significant increase in iron and copper units per nickel unit in the feed. The decoupling of the leaching and iron removal process steps has had significant advantages for the robustness and control of the overall circuit, in particular pertaining to the preparation of a nickel electrolyte of sufficient purity to produce LME grade nickel. This paper details the primary changes to the RBMR circuit chemistry with a particular focus on iron deportment and the benefits derived from the installation of the PIR autoclave.INTRODUCTIONAnglo American Platinum mines and refines Platinum Group Metals (PGMs) through a complex processing pipeline in its South African operations. Mined ore is first treated through several mineral processing stages, geared to the recovery of base metals and associated PGMs, followed by smelting and refining operations that aim to separate base metals from PGMs and recover the value components to purified, saleable products. The focus of this paper is the Rustenburg Base Metals Refiners (RBMR) complex which receives a PGM-containing converter matte, then physically separates PGMs and base metals, and recovers nickel and copper to cathode by utilising leaching, precipitation and electrowinning processes.With new mining operations coming online and the continued increase in PGM ore arisings, it was necessary to undertake an expansion project at the Base Metal Refinery (BMR) to increase production capacity from 21 ktpa to 33 ktpa Ni. Complicating the expansion project was the requirement of continued production through all stages of design, construction and implementation and, due to stringent capital constraints, the utilisation of all existing equipment installed during a previous expansion in 1981. Against this backdrop, the expanded BMR flow sheet involved significant changes to the chemistry, especially iron management. These changes in iron management allowed for the separation of iron and copper residues and significantly increased the robustness of the plant to changes in feed mineralogy as well as the potential to increase production duties of the existing equipment."

Jan 1, 2016

By R. Tremblay, M. Burrows

"In the summer of 1990, pilot scale testing of a Jameson cell was carried out at Falcon bridge Limited, Kidd Creek Division. The Jameson cell is self aspirating and has fewer mechanical parts, thus it has a lower operating cost compared to conventional cells. This lower operating cost combined with positive pilot scale results, justified the evaluation of two full scale cells in the plant. The plant test had two mandates:1. Gain a thorough understanding of the cells operation and design constraints.2. Develop a flow sheet to replace three divisions of copper cleaner flotation.This paper provides an overview on the installation, commissioning and evaluation of the two Jameson cells acquired. The current status of the test program is also discussed.IntroductionThe Falcon bridge Limited-Kidd Creek Division concentrator is located in Timmins, Ontario. The concentrator, commissioned in 1966 and expanded in 1978, consists of four parallel grinding and flotation divisions utilising small cell (60 ft3) technology. With increasing pressure to maintain low operating unit costs a series of studies were undertaken to assess the impact of new technologies in the flotation circuits. The goals of the project were to improve productivity through increased metallurgical performance and/or reduced operating costs.One of the technologies investigated was the Jameson cell designed by Dr. Graeme Jameson of the University of Newcastle and marketed by MIM Holdings Limited, Australia. This style of column technology was chosen based on its potential for reduced capital and operating cost versus large conventional cells.The success of pilot testwork in 1990 led to the installation of two production sized Jameson cells beginning in October 1991. The units were to be used to confirm pilot results and determine equipment requirements for flotation modernisation. This paper will discuss the results and experiences Kidd Creek has had with the Jameson cell from pilot scale through installation and commissioning of the plant units."

Jan 1, 1993

By J. O. Yeboah, V. Boakye, P. A. Bepswa, M. Lombard, G. Nutor

The comminution circuit at Tarkwa Gold Mine was commissioned as a Single Stage SAG mill operated in closed circuit with hydrocyclones designed to process 4Mtpa. The circuit was later expanded by adding a secondary ball mill in closed circuit with hydrocyclones with a view to treat 12Mtpa. The change in the circuit configuration and assigning the low aspect ratio SAG mill for primary grinding application makes the Tarkwa experience unique in terms the optimisation strategy and operating philosophy. This paper reports the findings from a series of surveys performed on this plant. The surveys reported include data obtained when the SAG mill was operated as a single stage mill in closed circuit with hydrocyclones and also SABC mode under two different feed conditions. The differences in operating philosophy between the initial single stage SAG circuit and the current SAG/Ball mill circuit are discussed.

Jan 1, 2012

By W. A. Gow, V. F. Harrison, H. H. Mccreedy

A semi-continuous bench-scale, countercurrent-decantation system, in which the ore was moved countercurrently to the flow of leaching solution, was used to conduct acid-leaching tests on uranium ore with the aid of bacteria. This method, which involved a low degree of agitation, was successfully applied to extract uranium in practical amounts and at practical rates. The acidity of the leaching solution was the main variable investigated in the bench-scale tests done at the Mines Branch, Ottawa. Over 90 11er cent of the uranium was extracted in a six-stage system. The results suggest that this technique could be ap-plied in the utilization of bacterial oxidation and leaching as a method for treating Elliot Lake uranium ore.

Jan 1, 1969

By V. K. Karra

"A simplistic algorithm jar simulating the rod or ball mill Bond grindability test applied to ores and minerals is presented. A performance comparison between the present algorithm and a previously published algorithm by Kapurot, modified in this work jar a fair evaluation, is also given. A worked example is furnished jar leading the reader through the various calculations.IntroductionThe Bond grindability test is widely used for the prediction of the power requirement of an industrial grinding mill. The procedures for conducting this test in either a ball or a rod mill are available(1). In the case of a ball mill, batch grind abilities have been correlated to Bond grindabilities to help monitor day-today variations in ore grindability for the purpose of plant control( 2,3). Of special interest is the algorithm presented by Kapur(3) for the simulation of the Bond test. In practice, the test lasts from 6 to 14 cycles (4 to 10 hours). With this algorithm, one can predict the Bond grind ability using information available from only the first two cycles.Sometimes the prepared feed for the grindability test contains too much fines compared to the total product desired at the mesh of grind under consideration. In such a case, the operator separates the fines from the test feed and adds to the remaining coarse fraction an equal amount of fresh feed. This combined feed then forms the feed to the first cycle of the test. In the present work, Kapur's algorithm is modified to include this special case. A new and relatively simpler algorithm is also presented. Statistical equations relating work index to pertinent variables are also given."

Jan 1, 1981

By A. Manohar Rao

Underground mining in general and more so the coal mining is a hazardous venture as it is a struggle against nature and natural forces. The stability of roadways has a direct impact on production and productivity. The roadway stability can be strongly influenced by the direction of the drivage. The stress studies are useful to provide a frame work for understanding the influence of drivage direction on roadway conditions, and to illustrate how mapping techniques can enhance this understanding. The act of mining can concentrate and re-orient the original stresses. Whenever coal is removed, the overburden weight that it carried is transferred. Vertical stresses are similarly affected when the roof is deformed or failed. The Singareni Collieries Company Ltd., a joint Public sector undertaking of the Government of Andhra Pradesh and India is conducting coalmining operations in the Godavari Valley Coalfield and is catering to the needs of a large part of South India. With the technology update, it is looking for safe mining and to achieve higher production. As a part of this, an attempt is made to understand the stress conditions prevailing on the mine blocks by different ways and means in terms of geology, structure and tectonics of the Godavari Valley coalfield, satellite imagery studies, cleat pattern, stress measurement studies conducted in different mine blocks, and stress mapping technique.

Aug 1, 2013

By G. Anger, J. Enser, H. Antrekowitsch, S. Koch

Homogeneous chemical composition and microstructure are always necessary, but not always attained in practice. As-cast aluminium alloys tend to have a segregation microstructure. Features of the cast structure, which affect subsequent processing or properties, can be altered by the homogenization. The main task of the Department of Nonferrous Metallurgy was to investigate the effect of homogenization treatment on precipitation hardening of aluminium alloys 6061 and 6082. The effect of the solution heat treatment (SHT) temperature on the mechanical properties was also analyzed. The homogenized and non-homogenized rolling slabs were produced according to the usual conditions and methods. The metallographic investigations were carried out on the as-cast samples, after homogenization, after the hot and the cold rolling mill, and after natural and artificial ageing. Then, Brinell hardness measurements and tensile tests were conducted on both alloys in order to examine the influence of the homogenization.

Jan 1, 2006

By M. J. deBastiani

The uranium producing division of Denison Mines Limited operates a 6,000-ton-per-day integrated mining unit in the Algoma area of Ontario. The property is located approximately one and one-half miles from Highway I 08, eight miles north of the town of Elliot Lake. The property was staked in 1953, diamond-drilled in ?late 1954 and 1955, and put into production in 1957. Since that date, the operation has produced $250,000,000 worth of uranium oxide from approximately 11,000,000 tons of ore milled, and paid $18,000,000 in dividends to its shareholders. The operation employs about I000 people, and monthly operating costs are approximately one million dollars. From these figures alone, it is obvious that it was necessary to develop and institute an adequate set ?of controls for effective management at all levels of supervision over a period of four years, a system of production and cost control was developed that enables us to effectively measure the pulse of the various phases of the operation at any given time.

Jan 1, 1963

By Hilden. M.

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

Jan 1, 2012