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By V. Aprahamian, G. B. Harris, C. W. White, M. Tangen

"In 2005, the Royal Canadian Mint (RCM) commissioned a new silver electrorefining circuit. This circuit was intended to operate with a minimal electrolyte bleed for the control of copper. However, by the time of start-up, the levels of copper-rich silver doré to electrorefining had increased, and despite partial pyro-conversion in a small Top Blown Rotary Converter (TBRC), copper concentration in the silver anode still averaged 7.5%. This necessitated frequent replenishment of the electrolyte with fresh silver nitrate since copper displaced dissolved silver during electrolysis, and therefore requiring a robust copper bleed treatment step in order to maintain cathode silver flake purity at 99.99%. The originally-installed bleed treatment system could not meet the RCM’s needs. A thorough review of known technologies, however, did not indicate one capable of handling the copper load, and resulted, therefore, in the development of a novel copper hydrolysis approach for removal of copper as an insoluble basic nitrate salt, and recovery of the associated nitric acid for re-use in the circuit. Laboratory-scale trials showed reproducible results, and existing equipment was subsequently modified.INTRODUCTIONIn 2005, the introduction of a new silver electrorefining circuit at the Royal Canadian Mint (RCM) initiated changes in the way customer silver, collected from the gold doré circuit, was processed. These circuit changes were discussed in a recent paper (Aprahamian, 2015). A wastewater treatment plant had not been budgeted at the time, and this represented a significant constraint when considering the introduction of a wet processing circuit. After a review of various options, a turnkey silver electrorefining circuit was purchased from a European firm. Initially, enough cells were ordered to produce 2 million oz of fine silver (999), with the option to increase to 5 million oz. The selected equipment was based on a Moebius cell design combined with a silver grain pressure dissolver to produce make-up silver nitrate solution. Additionally, an evaporator/hydrolysis unit included in the package appealed to the Mint Refinery, on the basis that it offered a simple way to bleed dissolved copper in electrolyte without generating effluent."

Jan 1, 2016

By D. Kulchyski, R. Thibault, D. Lamoureux

"Mine tunneling applications are sensitive to the leakage and friction performance of ducting systems. Improvements in performance can help project economics through reduction in drift height, booster fan spacing, fan electrical power requirement, and deferral of ventilation raise construction. Semirigid plastic ducting has enjoyed significant adoption in mine tunneling in recent years. This paper explores technical properties and performance aspects of this relatively new material application.INTRODUCTIONUnderground mining projects are sensitive to mine development cost and schedule to meet first production—both of which are defined to a substantial extent by mine access construction. The very nature of mine access development requires driving accesses into new areas and even mechanized and automated tunneling methods require ventilation. Until underground airways are connected, allowing a flow-through circuit, ducted ventilation is required to establish ventilation within any single-access (i.e.: dead-end) heading. See Figure 1 as an example of ducted ventilation. Improving performance of ducted ventilation systems impacts project cost and schedule in several ways:For drifts whose height is defined by overhead clearance above haul trucks or tall equipment, smaller diameter ducting will decrease heading size.With higher ventilation flows, activities can be less ventilation-constricted; secondary headings can be worked without restriction, which improves schedule.Given the ability to provide more air for a given fan power, blasting gasses can clear the face and mine more quickly so crews can return to work more quickly - allowing higher advance rates.Lower electrical costs – both due to lower power consumed by fans and with the requirement for fewer electrical stations to power booster fans."

Jan 1, 2019

By Renliang Shan

Site conditions of China?s coal roadways are complex and changeable, and scientific classification of them is the fundamental basis for coal roadway support design, with great significance for ensuring proper roadway service. Upon analysis of the issues, a commentary regarding the research progress on classification of the stability of rocks surrounding coal roadways in China has been achieved from the point of view of classification methods and indexes. The shortcomings and applicable scope of rock stability classification methods related to coal roadways have been analyzed. It has been asserted that combining artificial neural networks with fuzzy mathematics, combining fuzzy mathematics with grey theory, applying new avenues such as support vector machine algorithms or unascertained average classification, and making classification indexes more scientific are future directions for development of rock stability classification for coal roadways.

Aug 1, 2013

By D. Marcotte

The Rock Quality Designation (RQD) is a standard scalar measure of rock quality used in common rock mass classification systems (e.g. RMR, Q system). RQD is measured along diamond drill holes. RQD interpolation between holes is nontrivial. Despite the inherent limitations of drill hole data and the local complexities of structural geology, it is often the only information available for mining and major civil engineering projects. Therefore, maximizing the usefulness of this data is warranted. We derive a correction for directional effects that help reduce the bias and improve the accuracy of the estimations. The correction is derived with the aid of numerous simulations. It relies on simple information, the angle between the joint normals and the borehole axis (JO). A reference direction is identified as the borehole direction with smallest JO. A multiple linear regression model based on JO statistics in the various boreholes defines the correction model. The corrected RQD values are then interpolated. It is shown the method enables reducing the bias on RQD estimation by 50% and improves the accuracy of the estimates by 30%. The corrected RQD values show stronger spatial continuity than the raw values. The benefits of estimating the RQD indirectly by using joint frequency measures are also assessed.

May 1, 2003

By H. R. Huffman

"This paper reviews the history of iron powder production, and outlines the varions production methods. The uses of iron powder and the reasons for its use are also covered. The paper concludes with a look at future trends in powder metallurgy.INTRODUCTION TO POWDERSTHE IRON POWDER INDUSTRY is enjoying a very rapid growth. The annual consumption of iron powder is now at the 100,000-ton level, twenty times higher than it was at the end of World War II, and the yearly in-crease bas been almost consistent at 20 per cent. This is expected to increase, bringing the tonnage to 200,-000, or even (according to some experts) to 270,000, in 1970. In any event, powder metallurgy is expanding at high speed and making an important impact on the production of iron and steel products. Some indication of the faith in the future market may be indicated by the commencement of three new powder production plants in Canada with a total capacity of 136,000 tons annually."

Jan 1, 1969

This paper presents the results of research aimed at proposing new solutions in the area of belt conveyor elements. Many factors, such as energy consumption costs, and operating costs of belt conveyor elements, including belts, idlers and drives have an impact on the operational costs of conveyors. The paper presents special tests of new materials for the bottom cover of an energy-saving belt conveyor, which decrease rolling resistance. It also presents large-scale in-situ tests of a high-output belt conveyor for the purpose of simultaneous measurements of various types of conveyor belts (standard vs several energysaving types) under typical operating conditions of a lignite surface mine. Improvements in materials used for the bottom belt covers, supported by specially developed comprehensive tests of the new types of belts have provided valuable results of various proposed solutions. Since the tests of belts were done at exactly the same time and in the same operating conditions, direct comparison of the results is valid and should lead to a substantial decrease in the conveyors? drives? energy consumption, which will improve the effectiveness of belt transport and minimize its negative influence on the environment.

Aug 1, 2013

By Jonathan Peck, Jim Gray

"While the mine developer looks for bigger and better orebodies in countries offering lower risks to development capital, the opera-tor of existing mines is looking for bigger and better ways to use his existing resources. Mining operations today utilize a variety of stand-alone systems for planning and managing their operations. In both small and large mines, payroll, accounting, inventory, planning, and engineering requirements are met using a combination of manual and computer-based systems.Technical advances and new enabling technologies are changing how mines are doing business. PC-based systems are allowing small operations to join the larger mines in using advanced computer-based systems. Advanced monitors are being used in maintenance to track, predict and correct the health of production equipment. Production monitoring systems are used to measure the performance of operating equipment and personnel in real time. This detailed information on how much, where, when, and by whom is being used for proactive management and planning. Ultimately, this information can be used to optimize and control the machines’ activities, eventually leading to robotic and autonomous operation of mining equipment.As the use of technology increases in mining, specific information objectives are being met but other problems are being created. The life cycle of technology is small, and as current systems are replaced by newer ones, integration problems and additional end-user training are created. In addition, onboard monitoring systems can create large volumes of data, data which are frequently archived without being analyzed. Mine operators are also duplicating efforts applying new technologies in an effort to be more competitive, but in doing so are creating interfaces which are only compatible with their own facilities. As system development moved from the centralized mainframe computer to the PC environment, the fragmentation of these systems became more pronounced.To efficiently continue in adapting and utilizing advancing technology, the mining industry needs to develop a system architecture that readily integrates as many sub-systems as possible. This will provide a framework for existing system integration and design guide-lines for future development. The Total Mining System (TMS) concept will allow a network of stand-alone functional modules to be readily integrated with minimal effort. This paper will discuss some of the current technologies cur-rently in use in some surface mine operations.In addition, a description of the information system and communications requirements that will be needed to integrate these components in the future, will be discussed."

Jan 1, 1996

By J. C. Roy, S. Couture, C. Barbeau

The chemical composition of the asbestos tailings from different mines in the Eastern Townships of Quebec are fairly uniform in composition. The serpentine minerals antigorite and chrysotile form about 85 to 90 per cent of the total. Iron oxides add another 7 to 10 per cent; magnetite represents about 70 per cent of the oxides. Chromite is present in amounts of about 0.5 per cent. The average contents of elemental magnesium, iron and nickel are 23, 6 and 0.25 per cent respectively.

Jan 1, 1972

By S. J. Cook

Outstanding advances among the metals, marked the mineral production records for Canada during the first half of 1925. Production of metals and non-metals reached a total value of $90,347,698. as compared with $84,307,385. in the first half of 1924, an increase of 7.16 per cent. Metals and non-metals produced during the calendar year 1924 were valued at $17 4,202,537.; production during the first half of 1925 showed a sum equal to 51.86 per cent of this total. Advances among the metals were general. Gold rose to a new record. Lead advanced 62.41 per cent over the high mark attained in the first half of 1924. Nickel production was well maintained. Copper was up a million pounds. Silver showed increased values. Zinc followed the trend in lead to almost double the output recorded in the first half of 1924. Cobalt production continued to improve. Despite the loss due to the protracted strike in the Nova Scotia coal mines which reduced the output of coal in that province; during the six months ending June, to less than half the tonnage reported in the first six months of 1924, improved conditions throughout the rest of the non-metal mining field resulted in the production of non-metals during the half-year reaching a total value of $31,199,233. as compared with $36,844,286. in the first half of 1924; the loss in the value of coal output al one amounted to $5,723,873, while the decrease in the aggregate value of non-metals amounted to only $5,645,053.

Jan 1, 1925

By Douglas R. Schmitt

In general, knowledge of the state of stress within the Antarctic lithosphere remains largely unconstrained due in part to Antarctica?s inaccessibility and because of the paucity of seismic focal mechanism solutions. As such, an important component of the ANDRILL project was to acquire new information on the stress directions and magnitudes within the upper crust. Extensive fracture mapping of the core and oriented ultrasonic televiewer logging were carried out to provide strong constraints on both stress orientations and the faulting regime. The first hydraulic fracturing stress determinations in Antarctica were also carried out to provide complimentary stress magnitudes. These measurements were accomplished using a wire-line transported hydraulic fracturing system consisting, essentially, of two synthetic polymer packers that were inflated to isolate the 1-m long pressurization interval. The tests were conducted at the end of the drilling and logging in a ~130-m section specially drilled below 1000 mbsf (nearly 1500 m from the rig floor) for hydraulic fractures. This zone was drilled primarily through competent, dense, and low permeability diamicts. The core fracture and televiewer logging information was used to site twenty separate measurements. Classic hydraulic fracturing pressurization records with unambiguous breakdown and fracture closure pressures were obtained in about half of the measurements. The remaining tests provided fracture propagation and closure pressures that are consistent with the classic breakdown curves, but they did not include a clear breakdown pressure and are indicative of the reopening of either natural or drilling induced fractures in the wellbore wall. The preliminary analysis of the results are in generally good agreement with the stress directions indicated by the core fracture logging and the stress regime suggested by the character of the drilling induced core fractures.

Jun 1, 2012

By Ralph Harris, Javier Jara

"Oxygen is essential in gold cyanidation. It is supplied to the leaching media by sparging oxygen or compressed air into the cyanidation tank. The rate of oxygen transfer is critical to achieve the desired oxygen concentration in solution.The performance of a novel device for gas sparging recently developed at McGill University is compared to the mass transfer characteristics of the two spargers most used in the gold industry: the four lance configuration and the inverted cone. The distribution of gas and the kinetics of oxygen desorption of the three types of spargers was studied in a 140 litre tank. The oxygen dissolution of the new device is three to five times faster than the other spargers. This could increase the leaching rate and/or decrease the cyanide and oxygen consumption.IntroductionIn hydrometallurgical processing, it is often necessary to bubble gas through a pulp to carry out the wanted reactions. The gas can act to agitate the pulp and it can also supply reactant. The rates of the reactions which require a reactant supplied by the gas are often dependent on the rates of mass transfer from the gas to the solution.A common example of this is gold cyanidation which requires oxygen for gold dissolution. Since the gold containing slurry is rich in other oxygen consuming substances (sulphide like pyrrhotite), it is important to provide enough oxygen to allow complete gold dissolution within the residence time of the cyanidation reactors. It has been demonstrated that the rate of gold dissolution is directly proportional to the dissolved oxygen concentration of the pulp which in turn is proportional to the oxygen partial pressure in the bubble 1 2 3. Improving the rate of mass transfer of oxygen increases the dissolved oxygen concentration of the slurry and therefore improves the rate of the reaction.The rate of mass transfer from a bubble to its surrounding solution increases with decreasing bubble size and increasing gas bubble residence time which in turn increases with decreasing bubble size. The generation and dispersion of small bubbles is thus critical to achieving high rates of mass transfer. Different configurations and devices used to inject gas have different effects on the bubble size and the residence time, influencing the overall rate of mass transfer. Therefore better mass transfer can be achieved by adopting a more efficient method.The methods tested in this report are the four lance configuration (wall spargers), the inverted cone and a new device, designated HCD. The wall spargers and the inverted cone are used widely in the industry today."

Jan 1, 1994

By T. Billotte, G. Tirand, J. Zollinger, V. Robin, B. Rouat, D. Daloz

The grain structure prediction of metallic alloys during a welding process is often an issue. In addition to the welding parameters and the alloy nominal composition and properties, the base metal grain structure and chemical homogeneity also play an important role in the formation of the final microstructure. In this paper intensive characterisation of solidification structure in gas tungsten arc welding of Ni base alloy 600 are described. It is shown that in transverse section of the weld, while the grain structure shows some texture following constrained solidification growth, grain density in the weld is similar or greater than grain density in the heat affected zone. This suggests that simulation of the welding structure needs, in order to be predictive, to take into account : epitaxial growth, secondary nucleation events and 3D growth inside the weld pool.

Jan 1, 2015

By Y. Chengxian

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 Mark Kennedy, Allan MacRae, Cameron Hams

New technology projects, particularly those involving first-of-a-kind metallurgical facilities, have a poor track record of achieving their overall financial targets, as they incorporate technological risks in addition to normal project risks. Traditional project management tools focus on risk from concept development through implementation, but typically fail to address the additional risks associated with a new technology project including slow start-up, slow ramp-up, and failure to achieve design performance (quality or throughput). These additional risks affect future cash flows produced by the project and hence its value, typically measured as net present value (NPV) or internal rate of return (IRR). Common accounting practice is to reduce the present value of future cash flows by applying a chosen discount rate, often reflecting the corporation's cost of capital. This discount rate does not contain an allowance for technological risk, which is often underestimated or misunderstood by both the financial and engineering project managers. This paper will focus on the topic of project risk and new technology, and how these play a role in the probability of achieving the predicted future cash flows. By properly addressing technological risk in the form of risk-weighted returns, marginal projects can be prevented from proceeding, while sound projects can be given the additional time and resources required to achieve the optimal level of front-end-loading (the level which returns the maximum risk-weighted net present value). A simple set of mathematical tools should enable engineers and financial professionals to establish a common level of understanding, thereby leading to a more accurate assessment whether a new technology project is ready to pass through its next level of approvals.

Jan 1, 2011

By V. Labiouse, F. Orellana

"Hollow cylinder samples can be tested for both the characterization of rock properties and the physical modelling at reduced scale of engineering applications. Particularly, this type of experimental setup can be used to simulate different stress conditions around underground openings, as already developed in the petroleum engineering field e.g. to study the instabilities around deep wellbores during either drilling or the oil production phase. Some authors have also used this technique to successfully characterize the damaged zone around underground openings in the tunneling engineering field looking for an efficient design of their support.This article presents a new hollow cylinder testing device developed at the Rock Mechanics Laboratory of the Ecole Polytechnique Fédérale de Lausanne (EPFL), Switzerland. It allows a full and independent control of the confining pressure and pore water pressure conditions at both the inner and outer boundaries of Thick-Walled Hollow Cylindrical samples. In order to mimicking a tunnel excavation in a porous rock mass, after initial recovery of the in-situ stress and pore water pressure, the hollow cylinders are subjected to a decrease in the internal confining pressure. Moreover, X-Ray Computed Tomography scans of the specimens are performed through the testing cell before and after the mechanical unloading to monitor the displacements undergone and the sample damage. The equipment, testing procedure and data analysis techniques are briefly presented in the paper.The good performance of the apparatus has already been checked on weak rock specimens, among others on Boom and Opalinus Clay samples. In many configurations, the mechanical unloading is found to induce a Damaged Zone (DZ) around the central hole. Its geometry and extent show a great similarity with in-situ observations around tunnels driven in the Boom and Opalinus Clay formations. Such similarities contribute to increase confidence in the understanding and modelling of the ongoing processes."

Jan 1, 2015

By P. E. Cavanagh

THE Ontario Research Foundation has developed a family of dry magnetic concentrators which, when used in conjunction with a dry grinding mill such as an Aero-fall mill, will allow the production of a completely dry magnetite concentrate. Previous experience with extrusion of iron ore and with pelletizing of fine iron concentrates suggested that it might be possible to develop a method particularly suited to the agglomeration of completely dry concentrates which might have some practical advantages over other methods of agglomeration. Pelletizing is the preferred method of agglomerating very fine iron ore concentrates. Magnetite concentrate is fod to the pelletizing equipment in the form of a moist filter cake. Binders and plasticizers may be added if necessary, and the moisture content must be increased or adjusted to the percentage necessary to give good balling action and satisfactory green strength in the resulting moist pellets. The moist ore with a closely controlled water content of about 7 to 12 per cent moisture may be rolled into pellets by a snow-balling action in a pelletizing drum, a Lurgi pan, or a Mac-Dowell disc pelletizer. The resulting green pellets are fired by one of several alternative processes to produce a hard pellet which has sufficient strength to withstand handling and shipping.

Jan 1, 1957

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 Roger K. M. Bellows

The last coal-fired power plant to be built in Canada came into operation in 1994. Since then, Canada?s electricity requirements have grown substantially but no new coal-burning plants have been built. This country has abundant resources of coal from coast to coast, but in recent years, this has not affected our choice of fuel. In many other countries this is not the case, and the use of coal is growing rapidly. Although this presentation covers the topic from an Alberta perspective, some of the conclusions can be extrapolated to the rest of the country, and perhaps even to other countries. The coal found in the Alberta plains is particularly attractive because of its low cost and low sulphur content. Yet coal is no longer the fuel of choice, and a long-standing provincial government policy to favour coal for electricity generation has been ignored for more than a decade. Considering the lack of good alternatives, it seems obvious that we should look to coal as our primary energy source in the generation of electricity and for other industrial applications. This paper discusses some of the reasons that coal has fallen out of favour, particularly with respect to electricity generation. The significance of the deregulation of the electricity industry will not be ignored. In addition, the author will offer his opinion on the question of what it will take in order for coal to once again become the favoured fuel.

May 1, 2001

By V. A. Chanturiya, T. N. Matveeva, N. K. Gromova, T. A. Ivanova

"The research is aimed at solving the problem of increasing the extraction of gold from refractory ores, which are the main source of growth in gold production in the next decades. The purpose of the research is the development and scientific substantiation of the reagent modes for flotation extracting of gold from refractory ores using eco-friendly low-cost herbal modifiers (HM), providing increase in gold recovery and quality of gold concentrates. In the course of research laboratory techniques for the preparation of experimental samples of HM were developed, which included the sequence of operations of grinding Heraclium leaves and stems grinding, 2-stages extraction at a temperature of 50-60 °C, short-term ultrasonic treatment, filtration and subsequent unification of extracts. According to the developed method, the experimental samples of HM and conducted research were tested to analyze their sorption and flotation activity related to the extraction of gold from refractory gold ores.New data on adsorption and flotation properties of Heraclium stems and leaves extracts (HSE) in selective flotation of Au-sulfide minerals were obtained using UV-spectroscopy, scanning electronic and laser microscopy and atomic force microscopy. The dimensions and shapes of adsorbed hydrophilic films of herbal reagents were identified and mechanism of formation of stable insoluble compounds on the surface of minerals in flotation was explained.Research flotation tests carried out on samples of refractory gold ore of one of Russia deposits showed the possibility of effective use of herbal modifiers to improve qualitative and quantitative indicators of enrichment compared with the standard reagent regime. New reagent modes, using herbal modifiers in an amount of 5 to 10 ml of the extract (300 - 600 g / t, respectively) improves the quality of the concentrate: gold content attains 14.7 g / t, 1.34 times higher than in the baseline experiment and provides a gain of 3.13% extraction.The developed reagent regime with herbal modifiers is the author's original design, patented (patent of the Russian Federation) and have no analogues in the world of mineral processing. (Application number 2015116125 from 04.28.2015, ""The method of flotation separation of sulfide minerals using herbal modifier"", Russia). Actual application of new plant extracts as modifiers in flotation of sulfide minerals is the possibility of replacing of highly toxic chemical compounds by environmentally safe substances of plant origin. Implementation of the developed methods of extracting gold from refractory minerals with herbal modifiers will help to improve gold recovery at 3-5% and the quality concentrate of not less than 1.2 times, leading to higher productivity and a reduction of the negative man-made effects on the environment ."

Jan 1, 2016

By G. M. Ross, I. M. Ross, J. A. Scott

"The otherwise waste heat in many water streams in the mining industry can be used to provide space heating of adjacent infrastructure including laboratories, workshops, and offices. This can be achieved by using heat pump systems, which can work as a replacement or in conjunction with existing space heating. In the example investigated—process cooling streams at an ore smelter—the analysis provided illustrates that annual heating costs can be 19% lower and a simultaneous 62% reduction in CO2 emissions can be achieved.RÉSUMÉ Dans l’industrie minière, la chaleur qui serait normalement perdue des circuits d’eau pourrait servir à chauffer des structures adjacentes incluant les laboratoires, les ateliers et les bureaux. Cela pourrait se faire en utilisant des systèmes de thermopompes, qui pourraient remplacer ou s’ajouter au chauffage existant. Dans l’exemple étudié, des circuits de refroidissement de procédé à une fonderie, l’analyse fournie illustre qu’il est possible de réduire les coûts annuels de chauffage de 19 % et d’obtenir une réduction simultanée de 62 % des émissions de CO2."

Jan 1, 2016