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By Robert B. Parsons

"The mining industry is adjusting its sights to take a shot at the rising level of non-profit taxes which threaten to handicap the industry 's competitive advantage. In the case of this particular expedition, the industry evidentally has a strong ally - the country's mines ministers. It appears that an initiative is under way to assess the impact of non-profit taxes on mining in Canada as compared to other mining nations.IntroductionSeventy-five years ago, Canadians were unceremoniously introduced to something called income tax. Since then, income tax has been identified as the source of countless evils ranging from the common cold (attributed to stress) to the demise of the economy. Some years later, the provinces jumped on the bandwagon with their own income taxes, and later on with mining taxes. These profit-based taxes had some appeal to elected officials and to a segment of the populace. The onus of the taxes varied directly with the ability to pay (in theory, at least). Previously, the principal sources of government revenues had been property taxes and customs duties, which were viewed as possibly being somewhat regressive in nature.The mining industry has always had concerns about different aspects of income and mining taxes - the tax rate is too high or the depreciation rate is too low, and so on. Recently, though, the industry has turned its sights on the expanding array of taxes which are not based on profit, including payroll taxes, capital taxes, water taxes, sales taxes, fuel taxes, property taxes, environmental levies and user fees. The industry is seriously concerned that the rising level of non-pro fit-based taxes is not only hampering the industry 's ability to reinvest in Canada, but is also placing Canada at a disadvantage in terms of trying to attract new investment capital."

Jan 1, 1992

By K. Duckworth

The treatment of Turam data by conventional procedures does not permit the interpreter to make any estimate of induced current magnitudes. This problem may be overcome by using an alternative data treatment procedure. It is shown that the conventional and alternative procedures are equally satisfactory in terms of their ability to provide the location of line currents and estimates of conductor quality. A full description and evaluation of both procedures is presented in conjunction with field examples to show how the alternative procedure may assist interpretation when used to complement the conventional approach.

Jan 1, 1973

By C. Campero, C. Nicolau, L. Pagliero

The Chilean Congress has recently promoted desalination as a solution to meet the mining industry’s growing water demand. However, this rapid expansion of desalination infrastructure comes with trade-offs. This includes a significant energy cost for treatment, as well as socio-environmental impacts on indigenous communities, tourism, fisheries, and the marine ecosystem. This paper advances a regional-scale model for analyzing competing trade-offs through a case study in the Antofagasta mining region of Chile. Through geospatial data analysis in ArcGIS, new desalination infrastructure investments supplying water to mines are overlain with features of concern raised by communities during the environmental impact assessment (EIA) process, such as national parks, fisheries and exploitation areas for benthonic resources. The resultant model provides a test-bed for analyzing the cumulative effects associated with desalination expansion and for investigating scenarios to mitigate negative social-environmental impacts. The model simulates alternative scenarios for desalination locations and pipeline routes according to competing constraints (i.e. to minimize cost and energy constraints while also avoiding ecological and social hotspots). The ultimate contribution of the work is a demonstration of how the proactive adoption of a regional-scale infrastructure planning might have led to different desalination investment decisions. INTRODUCTION Chile represents the largest producer of copper globally, and holds approximately a third of the world’s estimated copper reserves. However, access to water represents a major constraint to industry expansion and creates conflicts with competing water users (Aitken et al., 2016; Côte et al., 2010). Recently, the Chilean Congress has promoted desalination as a solution to meeting the industry’s growing water demand, which is likely to lead to significant growth in desalination infrastructure to support large-scale mining projects that extract freshwater over a rate of 150 l/s1. By most recent projections, the Chilean copper mining sector is set to increase seawater use by 230% by 2029 (Faversham House Group Ltd, 2019). By the year 2015, Chile had 11 projects serving the mining industry and there are at least other 12 planned plants (Cochilco, 2015). While the use of seawater allows continued expansion of the sector without depletion of scarce underground aquifers, it is nonetheless accompanied with important socio-environmental drawbacks. One such challenge with desalination is the associated energy costs, expressed, both economic and environmental (e.g., CO2 emissions). This includes the energy required for reverse osmosis treatment facilities, as well as to pump water to inland regions at high elevations around 3.100 m.a.s.l in Chile. (Dixon, 2013; Knops et al., 2013). Additionally, the impacts of desalinated water use on flotation chemistry are generally poorly understood, necessitating the need for further research into the impacts, both positive and negative (Cisternas and Gálvez, 2018; Liu et al., 2011).

Jan 1, 2019

By J. Poplawski

In mineral processing plants, cyclones typically perform the classification duty prior to the downstream recovery process. Particle size distribution of the cyclone overflow is an important parameter and can be viewed as the product of the comminution process. Too coarse of a product will likely have poorly liberated valuable minerals and make recovery difficult. Too fine of a product may represent a missed opportunity to increase plant throughput and/or also result in low recovery due to poor kinetics. “Near-line” particle size measurement instrumentation has been in place for several decades, its availability and low measurement frequency have typically been inadequate for reliable use in automatic control. CiDRA Minerals Processing has developed a novel and robust technology that provides a highly reliable and low maintenance system for “on-line” measurement of the particle size in the overflow of individual cyclones. The system is based around a wetted sensor design with no moving parts and provides a real-time trend of the desired target grind size parameter. The system does not require sampling and associated sample transfer piping that is prone to plugging, thus avoiding high maintenance requirements. Plant data and benefits realized from the latest installations of the CYCLONEtrac PST will be presented. INTRODUCTION Impact-based real-time hydrocyclone particle size measurement Acoustic impact-based particle size tracking is a unique method for measuring and controlling the particle size in cyclone overflow streams. The implementation of this technology is centered upon a sensor probe that is inserted into the overflow slurry stream via a two-inch (50 mm) hole in the overflow pipe (Figure 1). Particles within the slurry stream impact the surface of the probe generating travelling stress waves within the probe. A sensor converts these travelling stress waves into an electrical signal and proprietary signal processing techniques convert these signals into a particle size measurement that is output every four seconds. The sensor is constantly in contact with many particles in the slurry stream, thus obtaining information from orders of magnitude more particles than traditional sample-based technologies. The sensor has no impact on cyclone performance because it is located downstream of the hydrocyclone and the presence of an air core ensures there is no change in the back pressure seen by the hydrocyclone.

Jan 1, 2019

By P. K. Chatterjee

"The operations of a large-scale open-cut mine are simulated to produce a user-oriented interactive digital model. SIMULA is chosen as the programming language and a sophisticated data base system is designed to consider the complex information network of large mines. The main features of the program are the mine planning and mine evaluation modules. These modules are responsible for the computation of truck-shovel performance and other equipment details in a mine. Stochastic methods are employed to generate event times. The use of a Data Base Management System and the data base provide an efficient method of information storage and retrieval. Truck allocation techniques have been examined in detail and comparisons between random dispatching and conventional methods are made. The model is intended for mine operators and engineers and the program is well structured and very readable. It is hoped that these features will make the model readily acceptable.IntroductionThe Department of Mining and Metallurgical Engineering at the University of Queensland has been conducting research into computer simulation methods in mining since 1972. The research has been mainly applied to actual operations, with both open-cut and underground mining being equally emphasized. The results of the research to date have not only strengthened the methodology of the approach to complex mining problems, but have also increased confidence in the use of modelling and computer simulation technique s in mining.The model described in this paper translates a complex LHD situation into a user-oriented interactive digital model using SIMULA. The present methods of evaluating truck dispatching and trolley assist are tedious and laborious. This model provide s the engineer with readily acceptable means of rapidly assessing the relative merits of these techniques in a large-scale open-pit operation. Poor utilization figures in many current operations (for example, 40% for trucks, 70% for shovels) are of serious concern to mine officials and computer-controlled dynamic truck dispatching systems have been considered by some of these mines to improve equipment utilization ."

Jan 1, 1981

By T. G. Joseph, A. Sharma

ABSTRACT: Ultra-class haul trucks operating in oil sand face operational and maintenance issues as a result of soft underfoot conditions (Joseph, 2002). With exposure to frequent high g loading events, tire life is reduced due to sidewall belt fexure and frequent ground contact. Therefore, an improved under-standing of the interaction between tires and oil sand is needed. This paper examines the outcomes of a series of static and cyclic loading tests, performed using a scale tire on rigid, sand, and oil sand surfaces. Geometric predictions are made regarding the footprint area and vertical deformation of an ultra-classtire on similar surfaces.

Jan 1, 2011

By M. P. Tixier

Abstract In a review of the application of electrical logging in Canada, examples are .given of long and short distance correlations by means of the electrical logs. The use of MicroLogging for the determination of permeable and porous formations is explained. The question of log analysis for the quantitative determination of fluid saturation and porosity is .discussed. An example is provided to illustrate the significance of the resistivity gradient. The advantages of the new method of the Laterolog are shown, chiefly for the case of wells filled with high-salinity mud. Introduction Electrical logging techniques developed rapidly in Canada at the time an intensive drilling activity started for the exploitation of the Devonian series in Alberta, namely, at the beginning of 1947. The conventional service was soon thereafter supplemented with the latest technica1 improvements. Canada has been among the first regions to take advantage of MicroLogging*, which has proved a most powerful .tool for the investigation of permeable and porous formations; also, the more recent development known as the Laterolog has ?been introduced in Canada. The Laterolog provides a better determination of .the formations, particularly in the case of salty mud where the conventional logging is greatly handicapped. The various methods of electrical logging are now commonly known in oil industry and have been described in numerous publications ( 1) ( 2) (3).

Jan 1, 1951

By G. M. Brownell

Introduction Within the past year a new deposit of gypsum has been opened up and brought into production in the Province of Manitoba. Until 1930, Manitoba's entire production came from Gypsumville, northwest of Winnipeg, at mile 161 on the Gypsumville branch of the Canadian National railway. However, during 1930 a gypsum bed was opened up at a point one mile south of the village of Amaranth, forty miles north of Portage la Paririe, on the west side of lake Manitoba (See Figure 1). Although no exposure has yet been discovered, the presence of gypsum below the surface in that district has been known for many years as the result of drilling for water. In 1929, J. R. Spear (1), of Winnipeg, interested some local capital in the possibility of .finding commercial deposits of gypsum, and, after some exploration work in the area with a well drill, the Amaranth deposit was located. Sixteen holes were put down at intervals of 400 or 500 feet, all of which encountered what appeared to be a continuous bed of gypsum, about thirty-eight feet thick, at a depth of 92 feet. The extent of the deposit has not yet been determined.

Jan 1, 1931

By A. P. E. Dirige

The stability design of cemented backfills is normally conducted using conventional approaches. Analytical or numerical models, backed by trial-and-error methods, are the primary means used to describe or predict the support performance of backfills during mining. The stability of paste backfill free-standing faces is a major concern due to potential consequences to production, ore dilution and safety. Available analytical or mathematical models are developed based on assumptions of the failure modes that may occur when vertical fill faces are exposed during adjacent mining. Numerical modeling serves to provide an understanding of backfill strength and deformation behaviour. Such approaches offer inherent limitations and generally result in conservative designs. In this paper, centrifuge physical modeling was conducted not only for performance evaluation studies, including stability analysis, but to develop an understanding of the strength and deformation behaviour of paste backfill exposed faces when the adjacent ore zone is removed. The failure mode and mechanics of failure observed in the centrifuge model of a given prototype situation are discussed in detail. Centrifuge model results were compared to numerical modeling and it was concluded that a sliding block failure mechanism that resembles a circular slip appears to be the predominant failure mode.

Aug 1, 2013

By Bhawani Singh, Mahendra Singh, N. K. C Samadhiya

"Inherently anisotropic rocks occur in abundance at many rock engineering project sites in Himalayan region. These rocks pose difficulty in analysis and design due to their direction dependent strength behaviour. Moreover the strength varies in a non-linear manner with confining pressure. Mohr- Coulomb strength criterion is widely used by geotechnical engineers for defining strength of rocks subjected to given confining pressure. However, the conventional Mohr-Coulomb (MC) criterion suffers from the limitation that the strength is treated to be linearly dependent on confining pressure. In the present article, the MC criterion has been modified by incorporating non-linear term while retaining the original parameters c and ?. The non-linearity with confining stress level has been imbibed through critical state concept (Barton, 1976). The criterion has been applied to a triaxial test data base comprising of more than 1140 triaxial tests conducted world-wide on anisotropic rocks. Statistical evaluation of the goodness of fit of the proposed criterion to the data-base has been carried out. Further the predictive capabilities have been evaluated by determining the error in estimation of triaxial strength if only few triaxial test data are available for determining the criterion parameters. The data base has also been back-analysed to assess the critical confining pressure for anisotropic rocks. Statistically the critical confining pressure, for the present criterion, may be taken nearly equal to 1.25?cmax, where ?cmax is the maximum value of the UCS out of all orientations of planes of anisotropy. It is concluded that reasonably good estimates of the anisotropic strength are possible through the proposed criterion.INTRODUCTIONMany rocks encountered in Himalayan region like shale, slate, schist and phyllite are inherently anisotropic and exhibit direction dependency in their strength behaviour. In addition, the strength of the rock also depends on the confining pressure and, the strength response is non-linear especially when the confining pressure may vary over large range. Conventionally, Mohr-Coulomb criterion is the most widely used criterion for rocks. However, the limitation of this criterion in its present form is that the strength is treated to be linearly dependent on the confining pressure. The present study attempts to address the following two main objectives: i) Include nonlinear response in the Mohr-Coulomb criterion while retaining parameters c and In their original form; and ii) consider anisotropic response of the rock for a given confining pressure. A nonlinear strength criterion, which uses shear strength parameters c and as per Mohr-Coulomb criterion, has been suggested based on critical state concept for rocks."

Jan 1, 2015

By Afshin Sadri, Wai Lai Ying, Brycklin Wilson, Zoe Coull

"Although there have been great steps forward to integrate corrosion engineering into operations, there is still an underlying tendency for maintenance tasks to be performed in a reactive manner. This is especially true when strategies focus on lagging indicators such as visual inspections, RCA (root-cause analysis), and FMECA (failure mode, effects and criticality analysis). This trend to “reactive maintenance” can be avoided by utilizing more inspection and monitoring methods to identify leading indicators of failures. Prevention is generally less costly than repairs; moreover, when paired with appropriate monitoring techniques, intervention of corrosion protection can be more effectively timed and based on more accurate data. Hatch asset reliability studies show nearly 80% of defects are introduced through operations and maintenance. Therefore, proactive corrosion management can provide the necessary feedback to optimize operations and maintenance strategies preventing costly corrosion losses. Understanding corrosion risks gives a clear picture of the benefits of a proactive approach to asset performance. Monitoring techniques (Non-Destructive Testing, field testing, sampling, etc.) by nature are a more effective means of improving maintenance efforts and preventing corrosion losses than other methods (RCA, FMECA). This paper will outline the importance of proactive corrosion management and demonstrate its benefits through industry examples.INTRODUCTION Over the past few decades, with the growth of technology and awareness of sustainable development many studies have shown the benefits of a proactive approach to maintenance strategies. However, in practice there is still an underlying tendency for maintenance tasks to be performed in a “reactive manner”. This is especially true when strategies focus on lagging indicators such as visual inspections, RCA (root-cause analysis), and FMECA (failure mode, effects and criticality analysis). This trend to “reactive maintenance” can be avoided by utilizing more inspection and monitoring methods to identify defects and leading indicators to failures."

Jan 1, 2017

By Garston H. Blackwell

For ageing open pit mining operations where the economic viability of another pushback is questionable, mine life can be extended by increasing the wall slope. If the steepening is started where ore intersects the pit wall, the capital outlay for waste stripping is minimal. Such a venture must be conducted safely, and a basic requirement would include loading equipment capable of working remotely. In the application described, alternatives in the choice of loader included equipment available on site, or the purchase and assembly of used equipment. Only electric cable shovels were in use at the operation, and it was thought that these would be more capable of digging high muck piles at the productivity demanded by an increasingly efficient mill, and in a challenging environment less suited to a rubber tired loader or hydraulic front shovel. A decision was made to convert an older electric cable shovel to remote controlled operation and to include the application of semi-robotic control. The conversion was completed successfully and is described, along with methods developed for remote operation of a shovel, and the application of various sensors for semi-robotic operation. A plan of operations to mine out several completed double benches and make two quadruple benches with wide catchment berms is depicted. On completion of this task, the working benches developed would be wide enough to operate at near full production. Prior to moving the remote controlled shovel back into the pit, a large wall instability became active, eventually closing the operation. The instability could have been safely mined using the remote controlled shovel.

Aug 1, 2013

By Jochen Petersen, Alison Lewis, Cledwyn Mangunda

Run-off and waste water streams high in dissolved metal content are generated in all mining operations. The metals pose a threat to life due to their persistent bio-accumulative toxic (PBT) characteristics. Hence, there is a need to treat mine waste water effectively. Lime precipitation is the technology of choice through which Fe, as the major metal species, is removed as Fe (III) oxyhydroxides with other metals co-precipitated and/or adsorbed. Sulphates are removed as gypsum or incorporated into the Fe phases. The resulting sludge has poor dewatering characteristics and is deposited in landfills, with an inherent risk of returning the Fe back into the water cycle through leaching. This study seeks to understand the mechanisms behind the formation of this sludge in terms of product quality. The relationship between process conditions and product characteristics has been investigated through exploring the effect of Fe (III) concentration on the precipitate product characteristics (particle size distribution (PSD), size, morphology and structure) and quality (in terms of filterability, settling ability, etc.) in a simplified system. Neutralisation of acidic synthetic aqueous Fe (III) sulphate streams containing 50, 400 and 800 mg/L Fe(III), respectively, was effected by mixing it in a continuous stirred tank reactor (CSTR) with dissolved calcium hydroxide for pH control at a residence time of 15 minutes. Precipitate samples analysed for morphology and PSD, using nanoSEM and Zetasizer respectively, showed a general decrease in PSD and zeta potential with increases in feed Fe (III) concentration. These results were used to infer the particle size enlargement mechanisms of Fe (III) oxyhydroxide precipitates under a given set of operating conditions. Preliminary product quality results indicate that a high concentration (800 mg/L) leads to the rapid formation of metastable precursors with poor product quality, whilst a low concentration (50 mg/L) leads to formation of thermodynamically more stable precipitates with good product quality. The approach demonstrates a potential route forward in terms of linking operating conditions to the attainment of desirable characteristics rather than specific precipitate phases which are difficult to identify.

Jan 1, 2016

By Barry W. Schmitke, J. M. Marino

"Cigar Lake Mining Corporation is presently operating an underground test mine in northern Saskatchewan, with a view to developing a high grade uranium deposit. The mining test is intended to demonstrate that the innovative mining methods designed are safe and economical. Two vertical mining methods are considered for the test:• box hole boring from the lower level;• blind boring from the upper level.In both cases, it is anticipated to freeze the ground before excavation to ensure hole stability and limit the inflow of water. Special care will be taken to minimize radiation exposure of personnel.Remote controlled equipment will be used where applicable.The access to the orebody was an important component of the test. After shaft sinking to a depth of 500 m, development work commenced at the 420 level in fractured sandstone which was grouted to restrict the inflow of formation water. The drifting continued in a section of poorly consolidated sand, clay and sandstone; this area was frozen to allow stabilization prior to excavation. At the 480 level relatively little water was encountered in the altered basement gneiss and grouting was not necessary; however, extensive ground support was required in the soft ground areas."

Jan 1, 1992

By Henry Smith, Stu Brown

"The Williams Mine is Canada's largest gold producer, with annual production of some 500 000 ounces of gold from two million tonnes of ore. Highly mechanized and automated underground mining practices are utilized at the property in order to help achieve high levels of productivity and the most cost-effective mining possible.Planning and design parameters for the underground ore handling system at the Williams Mine are described in this paper. Particular reference is made to the considerations that were built into the system to provide maximum operating flexibility through the use of multiple orepass systems, portable low profile jaw crushers, underground conveyors and automated hoisting equipment.IntroductionThe Williams Mine is situated in the Hernlo area of northwestern Ontario, approximately 40 Ian east of the town of Marathon (Fig. I). It is operated by the Williams Operating Corporation, which is owned equally by Teck Corporation and Corona Corporation, and is one of three adjacent properties forming the HernIo gold camp.The mine commenced operation in October 1985 at a nominal production rate of 3000 tpcd. Through an ongoing capital development program, winch was completed in late 1989, the production rate at the property was increased to its current level of 6000 tpcd. This paper describes the mine planning process and the evolution of current mining strategies with particular reference to the underground ore handling system .HistoryGold mineralization was discovered in 1944 in the Hemlo area of Northern Ontario, near the north shore of Lake Superior. A year later, 11 claims were staked over the showing and subsequently patented by the late Dr. Jack Kerr Williams.Over the next 35 years, other claims were subsequently staked, explored and abandoned in the immediate area of the 11 patented claims . In 1980 a predecessor of the Corona Corporation acquired claims adjoining the Williams property to the east. Drilling on this claim group started early in 1981 and intersected the Hemlo orebody in May of that year. In December 1981, Corona Corporation entered into an option agreement with Teck Corporation to explore and develop the property.A drilling program by LAC Minerals on the II patented claims discovered the Williams orebody in March 1982. The mine started production in 1985, pouring its first official bar of gold on December 6 of that year. Corona Corporation was awarded ownership of the Williams Mine conclusively by a decision of the Supreme Court of Canada on August 11, 1989. The court's ruling ended a legal dispute with LAC Minerals over the property initiated eight years earlier."

Jan 1, 1991

By J. Bakos

Solar Hydrogen Energy Corporation (SHEC Labs) recently constructed a pilot-plant to demonstrate a Dry Fuel Hydrogen Generation System that is powered primarily by sunlight focusing-mirrors. The pilot-plant consists of: A Solar Mirror Array and Advanced Solar Concentrator and Shutter System; and two thermo-catalytic reactors to convert Methane, Carbon Dioxide, and Water into Hydrogen. Results from the pilot study show that Solar Hydrogen generation is feasible and cost-competitive with traditional Hydrogen production. More than 95% of Hydrogen commercially produced today is by the Steam Methane Reformation (SMR) of natural gas, a process that liberates Carbon Dioxide to the atmosphere. The SMR process provides a net energy loss of 30 to 35% when converting from Methane to Hydrogen. Solar Hydrogen production provides a 14% net energy gain when converting Methane into Hydrogen since the energy used to drive the process is from the sun. The environmental benefits of generating Hydrogen using renewable energy include significant greenhouse gas and criteria air contaminant reductions.

Jan 1, 2005

By A. Zangooi, J. A. Finch

"A frother analysis technique based on the formation of a colored solution with UV-VIS absorbance proportional to frother concentration over a certain range has been developed. The calculation of concentration requires the comparison of the sample absorbance at a selected wavelength with a linear calibration (frother concentration vs. absorbance) constructed with values collected from solutions of known concentration (standards) at the same wavelength. It has been found that concentration ranges for preparation of standards can vary widely. An integration of our experiences into a databank can offer some guidance on the selection of standard concentrations. The databank includes results from the analysis of 37 chemical reagents, commercial frothers, and natural oils used in research work or at industrial sites. Grouping frothers by similar chemical structure or origin provides a good basis for selecting the standards to approach the maximum absorbance range for the spectrophotometer in use.INTRODUCTIONA technique to determine frother concentration on samples of industrial milling streams based on formation of a colored solution with UV-VIS absorbance proportional to frother concentration has been developed. The concentration is determined by comparison of its absorbance, at some selected wavelength, with those obtained by processing a series of solutions of known concentration (standards), at the same wavelength. It is desirable to have linear calibration (frother concentration vs. absorbance) over the widest concentration range. The upper concentration can be restricted by the instrument, as there is a maximum detectable absorbance (minimum transmittance), which can be reliably sensed by the UV-VIS detector (in most cases maximum absorbance is 3)."

Jan 1, 2016

By A. H. Onur

Spontaneous combustion of coal is a significant hazard in underground coal mines. It causes serious problems for miners for many years after the fact. It threatens workers? lives and causes economic losses for companies. It disrupts coal production and makes it necessary to abandon the main drift where the spontaneous combustion occurred. Coal fires have to be prevented before they occur; otherwise they are very hard to control. Precautions thus have to be taken in potentially risky areas. For coal to spontaneously combust, it needs 3 elements: fuel, oxygen and heat. If one of them is missing, the fire cannot occur. The best way to prevent spontaneous combustion is to prevent contact between coal and air. Coating of the coal surface with an air-proof lining material would be a practical and useful solution to prevent spontaneous combustion of coal. In the scope of this study, a lining material for coating the coal surface was designed at laboratory conditions. Lining material to be used for preventing coal fires should be airproof, cheap, sufficiently strong, have low rebound, be water- and heat-resistant, and easily obtained and applied. It should also be safe for human health when in contact with mine ventilation. By considering these obligations, 3 kinds of gypsum (plaster, satin plaster, molding plaster), as well as lime, cement and fly ash and different mixtures of these materials were applied in laboratory conditions to form a lining material. Samples of lining material were subjected to uniaxial compressive strength tests to determine their behavior against roof loads. Although there is no need to carry any roof load, the lining material has to be sufficiently strong to stay in place on the applied surface. If the lining material is broken, coal and oxygen can react again. Air permeability and curing time of the mixtures were also tested in laboratory conditions. Then the tested mixtures were applied on a wall with a pump to test the applicability of mixtures. After all tests were performed in laboratory, the most suitable mixture was determined as the optimal lining material to prevent coal fires.

Aug 1, 2013

By Robert Maquil, Gilles Didier, Walter Steiner

"The 1580 m long dual-tube motorway tunnel Markusberg near Schengen, Luxembourg experiences strong swelling phenomena in each tube related to a 35 m wide diagonally crossing rock layer, some150 to 200m from the east portals. Overburden over the roadway is 26 to 30 meters. Tunnel construction started in 1998 and the tunnel was opened in 2003. The tunnel was driven downgrade from the West, the heave phenomenon started to occur as the tunnel approached completion. No indications of the presence of anhydrite and dissolved sulphates were known prior to tunnelling. Water samples had been taken from the beginning of construction and the concentration of anions and cat ions determined. Sulfate content was substantial, in one well it reached 22 mg/l, this high concentration requires the presence of other ions, in particular sodium and chlorine. Based on the knowledge at the time of construction heaving ground was removed from the tunnel invert and a free space was left below the roadway that is covered by a transversely spanned slab. In addition a series of posttensioned tiebacks were installed below the sidewalls. The void left in 2003 was 1.7m high and closed to less than 0.5 meters in 2007 then it became necessary to widen the free space. A central trench was dug with a height of about 2.5 meters and the benches were lowered.Level surveying had been carried out since 2002. In 2006 two extensometers were installed, one in the zone of strongest heave, the second at the edge of the swelling zone. The extensometer in the center of the swelling zone indicated heave with an essential constant rate with seasonal variations, the heave is concentrated in layer from 2 to 5 meters that heaved by nearly 300 millimeters within 5 years or 60 mm/year, which equals to approx. 1% extension per year. At the abutments heave rates of 20 mm/year where the support resistance is higher were observed. With data from other case histories a relation of heave rate with support resistance was established. Based on the numerous field observations hypotheses for the complex in-situ swelling processes, involving rock mechanics, mineralogical, soil mechanics and hydrogeological aspects were developed"

Jan 1, 2015

By Hämäläinen M., O. Hyvärinen, E. Jääskeläinen

HydroCopperTM is a new hydrometallurgical process for the treatment of copper sulphide concentrates, which has been developed by Outokumpu. The process includes chloride leaching of copper concentrate, solution purification and precipitation of copper(I) oxide, an intermediate product, which is reduced and cast into copper products. The reduction can be carried out by pyrometallurgical methods or hydrometallurgically in an autoclave. This paper discusses the thermodynamic and kinetic aspects of the hydrogen reduction of copper(I) oxide in an autoclave. The results of the laboratory tests are presented and discussed. Finally, the autoclave method is compared with other options.

Jan 1, 2004