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By C. Poon

For slope stability, knowledge of major and minor discontinuity sets that form the rock mass fabric is paramount for pit slope designs. Due to the increased awareness of health and safety in mining projects, efforts have been made to limit structural mapping in order to minimize the risk to personnel associated with approaching potentially unstable areas. Recognizing the importance of such safety precautions, Golder Associates Ltd. is applying a combination of techniques including 3D photogrammetry, conventional mapping and drilling with core orientation to enhance structural data collection. Photogrammetry uses digital photographs to produce a virtual model of a rock mass surface. The application of these techniques will be exemplified through an expansion design of an existing open pit. A comparison of stereonets obtained using these techniques showed some agreements, but also highlighted limitations of each method. The application of photogrammetry was found to be very useful in complementing the other existing techniques.

May 1, 2009

By A. S. H. Kabir, I-H. Jung, J. Su, S. Yue, M. Sanjari

The final mechanical properties of wrought magnesium alloys are mostly controlled by microstructure and crystallographic orientation or texture. In common magnesium alloys, grain coarsening occurs during annealing process and formation of undesirable basal texture cannot be changed markedly. The aim of this work is to investigate the effect of static precipitation on microstructure and texture evolution during annealing at 250 °C after warm rolling of Mg-Al-Sn alloy. Mg-3Al-3Sn (wt. %) alloy has been designed using thermodynamic modeling software, FactSageTM, based on forming target stable and incoherent Mg2Sn precipitate within the industrial deformation temperature range. Microstructures and precipitation were investigated by optical and scanning electron microscopes and macro-texture was measured by X-ray diffraction (XRD) techniques. It was found that static precipitates form in a large scale at the recrystallized grain boundaries and retards the grain growth during annealing. Slight weakening in basal texture was also observed during annealing.

Jan 1, 2014

By Roger Lacroix

Fuel cell application to mining has been indicated to be potentially beneficial to underground mine worker health and to energy efficiency. In order to define the economic advantages of using hydrogen fuel cell vehicles, a detailed study of operating and capital costs associated with underground loaders and power supply infrastructure has been carried out. The results show that for a typical medium-size mine, operating costs and infrastructure costs are less for the fuel cell option versus diesel. The reverse occurs for capital costs owing to the currently higher cost of fuels cells versus diesel engines. This disparity is expected to decrease given the decline in price associated with fuel cell technology advances. Related market issues for fuel cell manufacturers are also presented. Despite the difference in cost, the resources and mine infrastructure required to operate loaders, and base design of the mine loader, is similar for diesel and fuel call versions.

May 1, 2007

By Hung-wei Liu, Kevin Plucknett

Early attempts to manufacture titanium aluminides using blended elemental powders, through powder metallurgical processes, have been obstructed due to serious swelling during sintering. Although the use of pre-alloyed powder can avoid this undesired expansion problem, there are limited commercial powder sources available. Therefore, in the present research, fundamental studies on the synthesis of dual-phase (? plus a2) Ti48Al intermetallic materials is undertaken, in particular assessing powder manufacture. In order to produce pre-alloyed powders, highly porous Ti48Al pieces are initially sintered from elemental Ti and Al powder blends, and subsequently pulverised into powders. The powder size is then further reduced by use of either dry or wet milling processes (i.e. shatterbox grinding, attrition, or ball milling). Among these methods, shatterbox grinding has shown the highest efficiency, with a slight mechanical alloying effect observed. The manufactured powder morphologies and phases, as well the sintered material, will be discussed.

Jan 1, 2015

By Robert B. Parsons

"The annual onslaught of provincial budgets and tax changes is complete, and once again the Canadian taxpayer is being asked to dig deeper into his pocket to fund old and new programs. It is noteworthy that 1987 tax reform promised lower taxes, but a broader fax base. Five years later, we still have the broader tax base, but the lower faxes have gradually crept up to pre-tax reform levels. Surprise! Surprise!IntroductionThe last edition of Tax Notes commented on some important proposals announced in Manitoba's 1992 budget. In this issue, Tax Notes summarizes the 1992 budget proposals of British Columbia, Ontario and Quebec. These budgets reflect the continuing trend of transferring responsibilities and the related costs-from the federal government to the provinces. As well, the budget papers bear witness to the respective governments' political stripes. British Columbia, Ontario and Quebec are seeking higher tax revenues. Only Quebec continues to acknowledge the importance of the mining industry in its annual budget documents."

Jan 1, 1992

By A. P. Williams

"This paper presents an overview of plant electrical systems in general, a discussion of the problems that may occur due to plant growth, the maintenance required to maintain the reliability and safety of the electrical system, and the selectivity of the relay protection system. It is divided into two main areas: short circuit levels within the plant electrical system; and relay protection systems.This information is directed at maintenance supervisors, mine managers and electrical superintendents who have been away from detailed short circuit and relay coordination calculations for some time. It points out the potential problem areas within an operating plant electrical system. Short Circuit LevelsTheoryThe electrical equipment in a plant such as breakers, switches and starters has two short circuit ratings, the momentary rating and the interrupting rating. These ratings may be given in MVA or current (amperes) depending on the equipment and manufacturer's preference. Since for a three-phase system MVA and amperes are related by the formula"

Jan 1, 1987

By Sean Dessureault

Technological Revolution ?Information age ? brought about by: ?Low-cost processing, storage, information sharing ?Shared & integrated data ? Increasingly more sensors & data sources From data collection to data use ??Data mining??analyzing the huge volumes of data ?Key example used in MBAs: ?Wal-mart, Google Explosion of data, trickle of information ?Paralysis of action Outline Trying to provoke- What drives innovation now? ?Challenges in mining Data Action Approach ?Examples from research & consulting upon request Conclusions ?Unaddressed challenges (Research Opportunities)

May 1, 2006

Carrying Energy ?Energy ?Power, data, signal, hydraulics, pneumatics? ?Needs to be conveyed from a stationary point to a system in motion ?Cable Carriers (steel and plastic), Festoon Systems, Cable Reels and Bus Bars Polymer Cable Carriers ?Life Line for modern machinery ?Transmitting power, data, signal, hydraulics or pneumatic energy ?Constructed and designed to work in harsh environments, at high speeds and to do this continuously ?Meet a wide variety of cable (Media) requirements ?Virtually maintenance free ?High efficiency

Nov 1, 2011

By Heinrich Möller

The electro-oxidation of 0.1 M ethylene glycol at gold, platinum and gold-platinum alloy electrodes in different heat treatment conditions has been studied in 0.5 M NaOH, at room temperature. Poisoning of all the electrodes occurs. However, the alloy electrodes poison at a faster rate than the pure gold and platinum electrodes. This indicates that the initially higher activity of these electrodes cannot be the result of decreased poisoning through a "third-body" effect.

Oct 1, 2003

By R. A. Triglavcanin

Delivering dilution water and mixing this water with incoming feed slurry, addition of flocculant, maximising flocculant-slurry interaction to build aggregate size, unabsorbed flocculant percentage, volume average of solids volume fraction, momentum dissipation ratio, dilution recycle ratio, volume average shear, maximum shear rate at exit, aggregate size on exit, uniform discharge profile and more ? all of these need to occur in the right order and in the right proportions within the thickener feedwell, the secret to thickener performance.

May 1, 2009

By T. C. Cheng, G. P. Demopoulos

It is the object of this paper to discuss various options for improving the hematite process in terms of increased throughput hence lower capital cost and production of saleable quality hematite. With reference to increasing the throughput of the process, it has now been determined via the analysis of Akita Zinc Co's continuous industrial autoclave performance data that the process kinetics is limited by the rate of the hydrolytic precipitation reaction. By correlating the hydrolytic precipitation rate to supersaturation ratio, it is shown that accelerated kinetics can be achieved via the following measures: (1) in-situ neutralization with addition of zinc calcine; (2) elevation of temperature; and (3) dilution of feed; of which, the first one was retained for further evaluation. According to presented estimates, addition of calcine, amounting to only 2.6% of the total zinc calcine processed, can allow for shortening the retention time by at least 50%. Such drastic shortening of retention time may be either used to increase the throughput of a given autoclave circuit or alternatively to release autoclave capacity for clean hematite production. Hydrothermal treatment of the crude hematite product proved effective in producing clean hematite as according to laboratory tests, hence allowing the sulphur content of hematite to be reduced from around 4% to less than 1%. A conceptual flowsheet incorporating in-situ neutralization for accelerated kinetics with hydrothermal upgrading of crude hematite without sacrificing production capacity and with minimum upset of the plant's water balance is described.

Jan 1, 2004

By K. C. Corin, M. S. Manono, J. G. Wiese

Depressants play a crucial role in the flotation of PGM bearing ores as they prevent naturally floatable gangue (NFG) from reporting to the concentrate. This action is regarded as critically important because less dilution of the concentrate means lower costs for downstream processes. However, abnormal water conditions (such as high concentrations of ions) in the flotation system can modify the selectivity of these depressants. It is well known that the existence of selected electrolytes in water can alter the behaviour of some polysaccharide depressants by enhancing their adsorption onto gangue minerals and thereby prevent naturally floatable gangue from moving into the froth phase. Concurrently these same electrolytes may enhance frothability, owing to their stabilising effect on the bubbles within the system. Plant water at various ionic strengths was investigated against depressant type and dosage in order to understand electrolyte-depressant interactive effects during the flotation of a Merensky ore, using entrainment, rate of NFG recovery, and total gangue recovery as proxies. The study showed that the rate of NFG recovery per unit mass of water decreased with increasing ionic strength at all dosages, however the total amount of gangue reporting to the concentrate increased with increasing ionic strength at all depressant dosages. Thus, this paper attempts to consider the effects of both ionic strength and depressant dosage as individual factors within flotation. It further looks to investigate whether any interactive effects exists between these two factors when considered simultaneously.

Jan 1, 2016

By J. Lobel, M. Bourassa, J. A. Kozinski, B. Peng

Non-isothermal kinetics studies of the reduction phenomenon of electric arc furnace (EAF) dust generated in stainless steelmaking have been carried out. The dust was mixed with carbon as a reducing agent and dolomite as a binder to form pellets. A Thermo-Gravimetric Analyzer (TGA) was used to determine the weight loss of pellets heated at an average rate of 40 K/min. up to a temperature of 1500°C. The degree of metal reduction was calculated by considering the pellet weight loss, and evaporation of moisture, dust, zinc and lead at high temperature. The reduction process was divided into three different steps. The first covers the 300°C to 760°C temperature range (from 7 to 18 min.), the second step ranges between 760°C and 980°C (18 to 24 min.), and the third covers temperatures above 980°C. Each step is characterized by different chemical reactions. Non-isothermal reduction kinetics equations were set up to describe each step. The kinetics parameters such as apparent activation energies and frequency factors were established. It was found that the first step was chemically controlled, while the second step was diffusion-controlled. Reduction behaviour in the third step was strongly dependent on the initial carbon content in the pellet. Chromium oxide (CrO) could only be reduced in this last step. High temperatures and higher initial carbon content favoured the reduction of CrO.

Jan 1, 2001

By Piotr Malkowski

Studies on the properties of rocks heated to high temperatures are rather rare. Such research is occasionally conducted for example; in areas around nuclear power plants. The national Polish coal gasification (underground coal gasification, or UCG) project has, however, forced the analysis of the geomechanical properties of heated rocks in the vicinity of a designed geo-reactor. Ukrainian experience with UCG show that rocks up to 2 m from the burned coal seam be at a temperature > 600ºC. Such a high temperature will undoubtedly influence their physical properties. This paper presents studies on the strength and deformation properties of carboniferous rocks in the Upper Silesian region, where the UCG process is planned. Three types of rocks were tested: claystones, mudstones and sandstones. Laboratory tests of these rocks evaluated compressive strength, elastic modulus and weight loss. An evaluation of the results of the tests comparing the thermal conductivity of rocks and their specific thermal capacity was then carried out. All of the rocks studied were heated to 300, 600 and 1000ºC, and also evaluated at room temperature. This procedure shed new light upon the behavior of heated rocks in relation to their distance from the designed geo-reactor. The test results presented were developed within Research Task No. 3 ?Developing a technology of coal gasification for efficient production of fuels and electric power?, financed by The National Centre for Research and Development under strategic research and development programme ?Advanced Technologies for Energy Generation.?

Aug 1, 2013

By S. Gößling-Reisemann

Most copper ores contain valuable co-products such as molybdenum, gold, silver, nickel, etc. Sulphuric acid and steam are valuable by-products, which are generated dur¬ing copper production. The environmental impacts from mining and refining therefore need to be shared between these by-products and co-products, an issue in Life Cycle As¬sessment (LCA) referred to as allocation. There are different, recognised methodologies for doing so: burdens can be allocated based on the market values of these commodities, they can be allocated by mass, volume, molar amount, functionality, or other physical, technical or economic factors. All of these methodologies have their respective merits and restrictions, and the choice is usually case specific. Nevertheless, the choice between alternative methodologies can have dramatic effects on the LCA results. Recycling in LCA has to be handled in a similar way, as it essentially constitutes a special case of co¬production. The existing standards (ISO 14040 ff.) allow different methods for imple¬menting recycling and allocation into metal LCAs (open loop, closed loop, value cor-rected substitution, etc.), which are still a subject of discussion in the scientific community. However, the methodology used can significantly influence the ecological profile of copper and copper products. We will present an overview of the different methodologies available for including recycling and allocation and give an analysis of how the meth¬odological choice affects the final LCA results. This work will be followed up by quantitative case studies.

Jan 1, 2007

By Y. W. Pan, Y. R. Liu

The disturbed natural rock mass tends to equilibrium state accompanying with non-equilibrium evolution process which has significant influence on the long-term stability of engineering structure. The deformation development in the non-equilibrium evolution is determined by two intrinsic processes, trend to equilibrium and damage development, which can be illustrated by evolution of excavated tunnel. Thus the creep and damage must be taken into account in study of non-equilibrium evolution process. Within Rice’s irreversible thermodynamics with internal state variable (ISV), the conjugate force function which equals to zero is a convex surface which divide the stress space into two parts, called equilibrium and nonequilibrium stress space respectively. The concept of effective stress of non-equilibrium has been proposed, in which the stress difference (d - d ) are the effective driving forces of non-equilibrium evolution process with hardening and damage effective. The formulations of inelastic strain rate and energy dissipation rate have been recast in the form of effective stresses. The inelastic complementary energy (ICE) is proposed to measure intensity of non-equilibrium evolution of material system. The specific equations of conjugated forces and kinetic equations of internal state variables are presented. The ICE and rate of energy dissipation are all calculated to be used to evaluate long-term stability of geo-engineering. The results show that rate of energy dissipation may be more convenience and flexible than ICE for internal state variable constitutive equation of rock mass.

Jan 1, 2015

By G. Riveros

A new, continuous fire refining process for copper has been developed and tested at the 5 tph pilot scale. During oxidation, the blister copper flows through a packed bed of crushed refractory bricks counter-current to a hot oxygen containing gas. The resulting desulphurized copper flows then directly into a packed bed of charcoal for deoxidation. By controlling the air to natural gas ratio, both temperature and reducing conditions can be controlled. Based on extensive laboratory scale measurements of the rate of copper oxidation and reduction, the process concept was developed aided by process modeling and simulation. The industrial-pilot scale installation built at the ENAMI Paipote smelter in Chile, consists of two cylindrical, compact reactors, operating in line, with a designed capacity of 5 t/h of blister copper. The results of the industrial-pilot tests confirmed the feasibility of the new process. The blister copper processing capacity was increased to 10 t/h with satisfactory sulphur removal. The degree of oxidation as well the copper temperature was controlled with relative ease. The specially designed siphon block allowed for smooth tapping of the oxidized copper and separation of refining slag. The reduction of oxidized copper in the packed bed of charcoal appeared to be very effective while control of the degree of reduction according to the height of the bed ensured control of the oxygen content in the refined copper at the required level.

Jan 1, 2007

By Sang-Kyun Woo

The electric power conduit (EPC) in Korea has been constructed since 1978. Facing the challenge of safety and sustainability of the EPC, it is urgent to develop an inspection strategy and maintenance system for the structure based on the concept of life-cycle management. This paper introduces the newly developed mobile inspection and diagnostic system of the EPC. The novel aspect of this particular system is the integration of non-destructive mobile inspection techniques with BIM (Building Information Modeling) and LBS (Location-Based Service). BIM is an ideal tool and platform for developing an inspection and diagnostic system, and RFID (Radio Frequency Identification) is a useful tool to construct USN (Ubiquitous Sensor Network) for LBS. The goal of this research is to establish an EPC inspection and diagnostic system concept based on BIM and LBS using RFID. In this research, a BIM model of OPENTBM tunnel for EPC will be established to show the integration of 3D CAD with the inspection data. An EPC?s maintenance database, which includes the deterioration types of the structure, inspection records, and repair methods, was designed to interact with the BIM. The system will be implemented by the BIM with the related database, in which the construction geometry and all related information are stored. The proposed system was designed to utilize the inspection and diagnostic system under the USN environment using RFID in EPC directly.

Aug 1, 2013

By H. Alzraiee

Traditional planning methods such as CPM and PERT have been useful tools to manage construction projects. However, the underlying model of these traditional methods often seems to fail to represent real projects as they tend to assume no interrelationship between project components. In reality, project components have complex dynamic feedback process that requires modeling of inherent uncertainty in the execution of these projects. Nevertheless, this dynamic nature and uncertainty have not been explicitly addressed by traditional planning methods. Project failure can be attributed to poor representation of the inner and outer aspects of operations that are responsible for project dynamics. Uncontrollable external forces are often cited but the real cause may be internal such as the feedback process among components of the project. An alternative perspective is offered in this paper through system dynamics (SD) that accounts for the feedback process and discrete event simulation (DES) for modeling the uncertainty. The proposed method utilizes SD method for modeling project dynamics and DES method coupled with CPM network for operational details and uncertainty, respectively. A case study that involves preparing engineering drawings in a design office is used to demonstrate the use of the developed method and to highlight its capabilities. Modeling the dynamic dimension is expected to enhance planning and scheduling of construction operations and to provide a better understanding of the impact of various internal and external factors on project schedule and productivity performance.

Aug 1, 2013

By P. Fleming, W. Pascheto

"Rod mills processing nickel and copper ore experienced recurring failures of liner bolts. In some cases failures became very frequent, requiring constant mill intervention and consequently impacting process stability and operating costs. Investigation related to the causes of bolt failures involved a multidisciplinary approach with the participation of engineering, maintenance and operation. It included the determination of bolt failure mechanisms as well as the assessment of mechanical properties, fabrication quality and handling and installation procedures. In addition, other parameters affecting bolt performance such as mill and liner design, operating parameters and maintenance practices were studied. This paper reports the failure investigation results and proposed solutions for failure prevention. INTRODUCTIONOccasional liner bolt failures are common in rod mills. However, chronic bolt failures developed in rod mills processing nickel and copper ore caused frequent shutdowns for bolt replacement to an extent that affected process stability. At first, it was thought that the cause of recurring failures was related to bolt quality. The operation then submitted several failed bolts to failure analysis. However, it became apparent that bolt quality was unlikely to be the main cause of failures. The determination of root cause (s) then became more complex, requiring a multi-disciplinary approach to failure investigation, requiring the assessment of bolt installation methods, mill design, operating conditions and maintenance practices. The results of the metallurgical failure analysis and investigation of other possible causes of failures are reported here."

Jan 1, 2016