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By 12670

The Cigar Lake project will develop the world’s second largest high-grade uranium deposit. The Cigar Lake Phase 1 orebody contains approximately 226 million pounds U3O8 at an average grade of 20.7% U3O8. The mine, to be operated by Cameco Corporation, will use a unique water jet boring mining method to cut previously frozen ore. A distinctive ore handling design is required to handle the highgrade ore slurry exiting the mining machines. The ore will be crushed and ground underground, with the ore slurry then pumped to surface. Loaded into purpose-designed containers on tractor-trailer units, the ore slurry will be trucked to Cogema Resources Incorporated’s McClean Lake mill. McClean Lake will leach all of the ore. Forty-three percent of the resulting uranium solution will remain at McClean Lake for processing into yellowcake. The other 57% of the uranium solution will be shipped to Cameco’s Rabbit Lake mill for processing into yellowcake there. Detailed design for the Cigar Lake project is now underway. Barring regulatory or market delays, production could start up as soon as early 2006.

Jan 1, 2004

By Peter Claus

In the last years, supported gold catalysts with particle sizes smaller than 10 nm have attracted a lot of attention. While gold bulk metal is rather inert in chemical reactions and, thus, is of low interest for catalysis, highly dispersed gold particles supported on oxides as TiO2 or ZrO2 show surprisingly high activities in some reactions important for the chemical industry. The oxidation of carbon monoxide at low temperatures is mainly used as model reaction to study the unusual properties of gold catalysts [1]. On the other hand, to evaluate the catalytic potential of gold, other chemical reactions which allow to control also the selectivity have to be considered. The selective hydrogenation of ???-unsaturated aldehydes to allylic alcohols is of both commercial relevance (e.g. in fine chemical and pharmaceutical intermediate production) and specific scientific interest [2]. Note that thermodynamics favors hydrogenation of the C=C over the C=O group (stronger negative free reaction enthalpy of 35 kJ/mol), and for kinetic reasons the C=C bond is more reactive than the C=O group. Thus, in the presence of most of the conventional hydrogenation catalysts, based on Pt, Rh or Pd, -unsaturated aldehydes such as acrolein and crotonaldehyde are hydrogenated predominantly to the saturated aldehydes and only to a minor extent to unsaturated alcohols. Therefore, it is desirable to find catalysts which are able to control the intramolecular selectivity by hydrogenation preferentially the C=O group while keeping the olefinic double bond intact (Fig. 1).

Oct 1, 2003

By Eric Bain Wasmund, Lance Christodoulou, Julio Jairo Carmona Franco, María Fernanda Castillo, Jose Concha

"A number of technologies are in practice for selectively removing coarse gold from conventional grinding circuits. These circuits are often designed so that the grinding mill output is size classified, with large (or high density) particles being removed before the tails are returned to the mill. Because of the high relative SG of gold, and the fact that some forms of gold such as free gold do not break apart during conventional grinding, coarse gold can accumulate in the circulating load, and eventually be lost.Eriez has developed a flotation cell that uses fluidized water to enhance flotation of coarse particles. More than 40 units have been sold in industrial minerals, and we are now exploring applications for the HydroFloat® in the gold industry.Mineros S.A currently produces approximately 120,000 oz of gold per year by gravity concentrating alluvial gold ore with a mean particle size of 330 microns, followed by further concentration using a Falcon separator. A 400 mm diameter pilot-scale HydroFloat® was added to the tails of the Falcon to test whether additional gold could be captured. Enrichments of 50-600 times and recoveries normally in excess of 95% were achieved. This allowed direct smelting of the gold concentrate. Metallurgical results and operating parameters such as water addition and power will be discussed during the presentation.This result opens the possibility that the HydroFloat® could be used directly in the grinding circuit, for removing coarse gold in the circulating load. This work also shows the possibility that the HydroFloat® can produce a throwaway tail, which will reduce the size of the circulating load stream and the grinding requirements of the circuit."

Jan 1, 2015

By Jacques Ouellet, Ferri Hassani

"Within the mining industry paste backfill technology has evolved over the last two decades. This technology aims at producing safe and cost effective backfill of high strength. When used as cemented backfill underground the usual practice in the mining operations was to consider the backfill as a component under the production engineer responsibility. With its growing use in various site conditions some problems were encountered. Over time the mechanical characteristics of paste backfill could deteriorate. Investigations on these problems brought an increased understanding of paste backfill chemistry. Effectively, paste backfill is produced with tailings slurry having sometimes very complex chemistry and mineralogy. The bonding agents can be sensitive to the chemistry of these slurries. Today, a new understanding of the complex chemical reactions involved in cementing paste backfill is derived from concrete research literature. Cemented paste backfill is a manufactured product and as thus all steps involved in its making must be looked at. Both the processing engineers and mining engineers need to be involved. The proposed paper will go over the various developments and new understanding gained over the years on paste backfill chemistry. The authors had the opportunity to work with various Canadian mines that implemented paste backfill in their operations. Chemical alterations case study will serve to illustrate the importance of a good understanding of cement and paste chemistry. The authors will then conclude on research orientations needed to bring a more efficient use of paste backfill technology. The crucial role of the processing engineers in the paste backfill manufacturing will be discussed.INTRODUCTIONPaste backfill is usually prepared from a mixture of solids and water containing at least 15% particles smaller than 20 microns with the addition of binders for mechanical strength. Historically, tailings had been classified to extract the fines and only the coarse part was placed underground as sand slurry. Paste fill was researched in the last three decades to enable mining operations to use all the tailings, including fines, in backfill. The outcome of the early studies showed that paste fill provides high strength but due to preparation complexities and transportation problems is expensive. A greater understanding of the transportation mechanisms and advances in dewatering technology in recent years has resulted in more practical use of paste backfill."

Jan 1, 2002

By F. Dai

Due to difficulties associated with gripping in direct tension, indirect methods are commonly used to measure rock tensile strength. In this work, we adopt an innovative indirect tensile test method: Semi-Circular Bend (SCB) to measure the tensile/flexural strength of Laurentian granite (LG). The static tests are carried out with a servo-controlled material testing machine and the dynamic tests are conduced with a Split Hopkinson Pressure Bar (SHPB) system. Pulse shaping technique is adopted to achieve dynamic force equilibrium in SHPB to facilitate data regression. Finite element method is used to relate the failure load to the tensile strength. Strong rate dependence of the tensile strength is observed. The flexural strength is higher than the tensile strength measured using Brazilian Disc (BD). This difference is rationalized using the non-local theory. To further validate the method, a coupled Finite element/Discrete element method (Fem/Dem) in conjunction with the smeared crack model is utilized to simulate the fracture process during dynamic SCB tests. The resulting fracture patterns are qualitatively consistent with those from recovered samples. Both the experimental and numerical methods have validated the results and this new method is readily to be used for other rocks and other brittle materials.

May 1, 2009

By K. Wyper

"Gulf Minerals (Canada) Limited' s Rabbit Lake Uranium Operation is located in the northern portion of Saskatchewan, 198 miles southeast of Uranium City and 134 miles northwest of Lynn Lake Manitoba.This paper describes flow sheet changes to solve operating problems and briefly describes future changes to accommodate the new ""B"" Zone ore.The Rabbit Lake mill was designed to process 1600 dry tons per day of uranium ore, with an average grade of 0.370 percent u3o8. In 1981, the mill processed 2040 tons per day at a grade of 0.231 percent u3o8 . The process modifications and flow sheet changes that allowed this increase in tonnage will be discussed in relative chronological order. Mill feed was introduced on June 10, 1975, the original equipment consisted of an Ingersoll Rand hydraulic breaker mounted over a 24"" square grizzly. The - 24"" ore was fed to a 2011 X 6"" seflli autogenous grate discharge mill close circuited with 20"" cyclones, the mill discharge was screened on a tyler double deck screen with the undersize (8 rnesh) reporting to the cyclones, the screen oversize was returned by conveyor belt to the mill feed chute.The cyclone overflow (28 mesh) was thickened in a 100' diameter thickener to obtain 55 percent solids for the leach circuit.The leach circuit consisted of two slurry holding tanks and five leach tanks."

Jan 1, 1982

By Jr. Fackler

The ionization potentials of gaseous Group 11elements are similar, with Au(0) being 1.5 eV greater than the next highest member of the group, Cu(0). The ionization potentials are all very much greater than the alkali metals, making these ?coinage? elements rather unreactive to chemical oxidation. Ionization from the first oxidation state shows a different pattern, with Ag(I) being the most difficult of the Group 11 ions to lose an electron. Gold(I) is noble and only normally oxidized in the presence of strongly coordinating ligands such as thiols or cyanide. Gold(I) compounds are 2-, 3- and 4- coordinate, with 3-coordinate species generally showing visible photoluminescence under UV excitation. Dinuclear Au(I) compounds with strongly coordinating S or C ligands can be oxidized to form isolable metal-metal bonded Au(II) compounds which are often readily isolable. Many have been structurally characterized. T he ease with which electrons are lost from closed shell dinuclear sp ecies (with anti-bonding M-M interactions) increases when metalmetal bonded compounds are formed. T his observation was made by our group with oxidative-addition studies of dinuclear gold(I) ylide complexes. It was superbly demonstrated recently by Cotton?s group who reported the isolation and characterization of a dinuclear closed shell transition metal species which is more readily oxidized than cesium. Trinuclear Au(I) pyrazolates, TR(pz), carb eniates, TR(carb), and benzylimidazolates, TR(bz), are well known and undergo electron loss through oxidative addition forming Au(I,III) mixed valence species and ultimately trinuclear Au(III) species. Au(II) species are absent from isolation in these oxidations. These carbeniates and benzylimidazolates also are excellent bases for metals ions such as Tl(I) and Ag(I). The acidic, neutral trinuclear compound [Hg(C6F4)3]3 also interacts with these bases. We have also shown that the neutral organic pi acids C6F6 and TCNQ form stacked pi-acid pi-base products with the trinuclear Au(I) compounds. In this paper, the structure of the octafluoronaphthalene acid-base product will be described. It displays a feature not observed previously in that the product is photoluminescent with a bright yellow emission. The 3.5 ms lifetime is very long and reminiscent of the long lifetimes observed by Balch for the stacked methyl,methoxy Au(carb). The electrochemical oxidation of tetragold(I) clusters, [Au4(form)4] have been studied in 0.1 M Bu4NPF6/CH2Cl2 at Pt working electrode at different scan rates. Three waves are obtained at 0.75, 0.95, and 1.09 V vs Ag/AgCl at scan rate 500 mV/s. The potential of the three reversible waves is independent of the scan rate in the range 50 mV/s to 3 V/s. The current at the third wave is larger than those at the first two waves. These tetranuclear species app ear to be effec tive catalyst precursors for the oxidation in air of CO. Introduction. The electronic structural relationships of the coinage elements and the alkali metals are similar in the sense that each have a [closed shell]ns1 configuration, yet their ionization energies (Table) and chemistries are clearly vastly different. The Group 11coinage elements have an underlying nd10 level immediately below the ns1 level. Unlike the alkali elements, ionization leaves the filled d electron shell the next accessible for further ionization. The coinage elements are all relatively ?noble?, much less reactive to environm ental conditions than the alkali metals. With the coinage elements, oxidation becomes very much dependent upon the types of ligand s availab le to bo nd to the ionized state.

Oct 1, 2003

By Stephen A. Gasiorowski, Frank J. Hrach, James D. Bittner

Separation Technologies, LLC (ST) has developed a processing system based on triboelectric charging and electrostatic separation that provides the mineral processing industry a means to beneficiate fine materials with an entirely dry technology. The environmentally friendly process can eliminate wet processing and required drying of the final material. The process requires little if any pre-treatment of the material other than grinding and operates at high capacity - up to 40 tonnes per hour by a compact machine. Energy consumption is low, approximately 1 kWh/tonne of material processed. Since the only potential emission of the process is dust, permitting is typically relatively easy. In contrast to the other available electrostatic separation processes that are typically limited to particles greater than 75 µm in size, the ST belt separator is ideally suited for separation of very fine (<1 µm) to moderately coarse (500 µm) materials with very high throughputs. The triboelectric particle charging is effective for a wide range of materials and only requires particle-particle contact. The small gap, high electric field, counter-current flow, vigorous particle-particle agitation and self-cleaning action of the belt on the electrodes are the critical features of the ST separator. The high efficiency multi-stage separation through charging / recharging and internal recycle results in far superior separations and is effective on fine materials that cannot be separated at all by the conventional electrostatic techniques. Since 1995, this triboelectric process has been extensively used for the beneficiation of coal fly ash with eighteen separators in place and over 100 machine-years of operation at locations in North America and Europe. The technology has been also successfully applied to the beneficiation of a variety of minerals including calcium carbonates, talc, and potash.

Jan 1, 2012

By Jack Zhang, Chuck Edwards

"The versatility and specificity of rare earth elements (REEs) have led to their use in an ever increasing variety of applications in new technologies. Consequently, demand for REEs has increased significantly. However, to separate REEs safely and effectively is a complex and expensive process. While China has consistently invested in R&D of REE processing technologies, there have been only sporadic activities in REE mineral processing in North America in the past 20 years. This paper presents a review of REE mineral processing technology, providing an update on current capabilities in REE mineral processing. This paper reviews REE extraction from the major commercially valuable REE-bearing minerals such as bastnaesite, monazite, and xenotime, and also from the ion-absorption type of REE deposits. Currently, there are four major REE mining areas in China, one in the United Sates, and one in Australia. A review of the REE extraction processes in these major REE mining areas closes out the paper.INTRODUCTION The rare earth elements (REEs) include the 15 lanthanide elements, plus yttrium and scandium. The lanthanide elements are normally categorized in two groups: the light rare earth elements (LREEs), i.e. lanthanum through europium (atomic number (Z) = 57 through 63); and the heavy rare earth elements (HREEs), i.e. gadolinium through lutetium (Z = 64 through 71). Yttrium is usually grouped with the HREEs due to similarity in physical and chemical properties. Table 1 lists the REEs, atomic numbers, and abundances in earth’s crust (Taylor and McCleannan, 1985). Promethium is the rarest due to lack of stable isotopes. REEs with low atomic numbers are more abundant than those with high atomic numbers. More interesting is that the REEs with even atomic numbers are much more abundant than adjacent lanthanide elements with odd atomic numbers as shown in Table 1."

Jan 1, 2012

By Olli Aulio, Outokumpu Oy

"GENERALThe Outokumpu Company is today an important European producer of metals from its own mines: copper nickel cobalt, ferro chrome and zinc being the main products. In 1972 about 4 million tons of ore was hoisted from eleven mines.Outokumpu Oy has gained experiences on the various aspects of on line computer control since 1968. This knowledge has been combined to develop a standard computer control package for concentrator control. Before the development of computer control package was started Outokumpu Oy had three large computer control systems. The first system was at the Pyhasalmi Concentrator, thee second at the LokkolaPlant, and the installation of the third system at the Vuonos Concentrator was just started.The characteristics of general computer software packages - both control and executive ones - were thus well-known as well as the practical usage of control theory. Furthermore Outokumpu had developed the Courier analyzer which included a so-called minicomputer. This project had given experience both 1n totally self made real tire executives and in computer hardware and peripheral d=vices. The instrumentation of the Outokumpu concentrators was designed and installed traditionally by the engineers of Outokumpu themselves."

Jan 1, 1973

By Nick D. Rose

The importance of structural geology in open pit slope stability is overlooked in many mining operations due to pressures to cut costs and minimize mine personnel. As a result, mine geology staff are often unable to keep up with geological mapping of the pit slopes due to other day to day production oriented tasks. In some instances, key structural controls that contribute to slope instability may not be identified until after a slope instability has initiated, at which time it may be difficult or impossible to delineate these features in the field. Even for small slopes, understanding the engineering and structural geology of the rock mass, as well as the effects of groundwater and blasting practices, are of key importance to slope stability. Two case histories are presented as examples of mining operations that experienced slope instability with little more than anecdotal information about the structural and groundwater conditions encountered during mining. By conducting field reconnaissance, simple slope stability analyses and ongoing slope monitoring, practical remedial measures were implemented, allowing continued safe mining operation.

May 1, 2002

By Derek Ettie

"In the Hydrometallurgical processes, the presence of the so-called "crud" is a constant challenge in solvent extraction. Crud is a stable emulsion which forms along the interface between the aqueous and organic phase. The spread is influenced by the following parameters: first, wind blows the dust and impurities into the open sedimentation tanks. Second, the undissolved solids such as sand transported in the PLS causing problems in conjunction with incorrect agitator design.The crud fraction can decisively impact the efficiency of the hydrometallurgical extraction because the phase interface can constitute a large fraction and the sedimentation tanks cannot react flexibly to it. In the downstream process of the series-connected sedimentation tanks, they are thus all contaminated with crud. At the same time, the necessary mass transport is significantly impeded at the phase boundary between organic phase and aqueous phase due to the crud formation.The transfer of the organic phase into the electrolysis cell can result in a "burnout" of the cathode. The carryover of this electrolyte into the extraction can cause problems with the pH regulation. The carry-over of the organic components into the raffinate also leads to contamination of the leaching circuit. The continuous treatment of the crud with a 3-phase decanter centrifuge is extremely effective in combating this problem. This technology splits all three phases from each other and they are consequently continuously separated. All subsequent process steps exhibit a stable, uniform effectiveness. The main advantage for the customer is that fluctuations in the process are eliminated and the organic phase can be recirculated back to the extraction. The recycling of the solvent alone justifies the investment in less than 6 months as examples from South Africa and Chile show.To operate solvent recovery in daily operation fully automated online at the optimum limit, the decanter centrifuge is equipped with a concentration-dependent pond adjustment called DControl® by this means, we can guarantee our customers the maximum possible solvent recovery and minimize the solvent costs in this process step. This system is presented in detail in this paper."

Jan 1, 2014

By J. Lee, M. Peart, T. Bhambhani, D. R. Nagaraj, P. Riccio

"Over the past decade or so, our efforts have focused on developing the rationale and concepts for new technology in reagent development and optimization in the processing of base and precious metals. A major outcome of these efforts have been the development of a novel family of collectors, principally driven by the MAXGOLD® and Aero XD-5002® chemistries, for precious metals recovery from primary Au ores and Cu-Au ores. These chemistries was developed to be robust to address the complex mineralogy and gold deportment in these ores. Plant trial data for a variety of ores have confirmed that the both Aero® XD-5002 and MAXGOLD® chemistry are indeed versatile in recovering gold values occurring as gold alloys and/or associated with many types of sulfides, and in altering the deportment of certain sulfides (such as those bearing As, Bi etc). An overview will be given in this paper using plant data to highlight the application of these reagents.INTRODUCTIONThe subject matter of this paper is the flotation of Au containing minerals from their ores. The motivation from this manuscript comes from the several challenges faced with the processing of Au ores, as was articulated in detail by Nagaraj (2008). The biggest challenge is the complex mineralogy; most easy-to-treat free-milling ores bodies are largely depleted. The Au values are distributed in multiple host minerals such as pyrite, pyrrhotite, arsenopyrite and Cu minerals such as chalcopyrite. Au values also happen to be finely disseminated within the various minerals and are sometimes invisible in optical microscopy. Additionally, on any given day, some mines treat multiple ore types, and the mineralogy is different for each ore type.Xanthates continue to be the collectors of choice at most Au and PGM operations around the world. Most primary Au operations tend to consume very large amounts of collectors; the dosage ranges anywhere between 40-400 g/t and this has been attributed to both mineralogical and non-mineralogical factors (non-mineralogical factors include the low cost of xanthates and the mindset that “more is always better”, which is not necessarily the case). In addition, several studies now show that xanthates alone are never sufficient where multiple value minerals are present, and that supplementary collectors are required. The large doses present a substantial cost to the minerals industry, and many mining companies have expressed the need for more efficient reagents that can improve metallurgical performance at low dosages."

Jan 1, 2013

By K. Awuah-Offei

Long-term production scheduling optimization has been a challenging issue for the mining industry because of the size and complexity of the problem. The current planning algorithms have limitations in terms of addressing the stochastic variables underlying the mine planning problem. In this paper, an intelligent agent-based mine planning framework based on reinforcement learning is introduced. The long-term mine planning is modelled as a dynamic decision network. The intelligent agent interacts with the block model by means of a stochastic simulation and employs a Q-learning algorithm to learn the sequence of pushbacks that maximizes the net present value of the mining operation. The intelligent open pit simulator (IOPS) was implemented with an object-oriented design in Java®. A comparative application case study was carried out to verify and validate the models. The proposed method was used in planning an iron ore deposit and the results were compared to the Milawa scheduler used in Whittle® software. The outcome of the study demonstrates that the intelligent agent framework provides a powerful basis for addressing real-size open pit mine planning problems.

Jan 1, 2008

By D. Schleiss

Reduced access to knowledgeable workers is creating challenges for operations. We are doing more 4D Operations - dirty, dull, dangerous, and distant. Personnel costs in these environments are high, and it is not always possible to get the people where you need them. Integrated Operations is a strategy to integrate people, process, and technology for faster and better decision making. Adopting an integrated operations approach can help to relocate personnel, improve collaboration, and align objectives to deliver reduced costs and improved performance. In this paper, the authors will highlight the required infrastructure to enable an Integrated Operations platform. Key decision points for enabling this technology for both Greenfield projects and existing mines will be discussed. Furthermore, the benefits and improved return on investment that result from deployment of an Integrated Operations strategy will be presented.

Jan 1, 2014

By David R. Macedon

"Through the years, a wide variety of dust control methods have been utilized at mineral processing operations. While some have been successful, many have been highly ineffective. Dust Control systems currently in use include baghouse systems, fog systems, surfactant spray systems, and foam dust suppression. While baghouse systems can be effective, they are capitalintensive and costly to operate and maintain. Chemical dust control programs can be very effective. However, if applied incorrectly, they can have detrimental effect on mineral recovery. Thus, many operations utilize a combination of baghouses and water, often with limited success.Recent advancements in surfactant and polymer chemistry have resulted in substantially improved chemical dust suppression programs. These products range from non-corrosive surfactant/humectant combinations for road dust control to foam-based systems for crushers and transfer points, to advanced polymers for pile binding and soil stabilization. These advances are discussed in detail, citing results from fieldwork in the precious and base metals industries.INTRODUCTIONThe global nature of the mineral processing industry presents a unique set of challenges. Traditional thinking would tell us what works in one place should work in another. This could not be further from the truth in the area of dust control. We learn very quickly that there are a number of factors that can affect the efficiency and success of a dust control program and that these factors are not all chemical or equipment related. Some of these factors include facility maintenance, product selection, water quality and characteristics, and economic considerations.What has been learned from past experience is that each mineral processing plant presents a unique set of factors that will affect the ability to create an optimal dust control program. This paper presents a myriad of treatment options that will highlight the advancements in chemical dust suppression products and equipment."

Jan 1, 2004

By A. Bamber

Canadian leadership in a global mining context will depend not only on entrepreneurship and best practice but also on technological innovation. This paper argues for more ambition and commitment to R&D for technological innovation in Canadian mining. It focuses on underground hardrock mining, where past R&D initiatives have simply not stood the test of time, and it is important to examine why. Concerns arise because industry’s commitment to R&D has not been sustained over time. Innovation through exploration, processing, and environmental technologies has been more significant. Meanwhile, R&D capacity and synergies in government institutions and universities have not been exploited. There is a need for more commitment, coordination, and collaboration by industry, governments, and universities. This paper examines some corporate models that have achieved sustainable innovation, along with some that have not. A strategy for innovation is discussed that relates to culture, commitment, coordination, and collaboration.

Jan 1, 2005

By M. M. K. McCrank

"PRACTICAL SAMPLING TECHNIQUESIt is important to achieve reliability when sampling heterogeneous materials where there is a difference in composition, and non random distribution of the constituent particles. Throughout the design, construction and installation of sampling systems it must be borne in mind that the sampling point must be capable of:-allowing each particle in the stream an equal opportunity to be sampled.-accepting and collecting as large a volume or mass of material as necessary to satisfy the requirements of particle counting statistics.-establishing a sampling plan so that the sample is representative of the whole to a defined standard of accuracy.Design ConsiderationsFactors that may influence the design of the sample point include:-the mass, or volume flow rate of the material being sampled-the size and shape of the material or flowing stream-the physical condition of the material being sampled (i.e. temperature, wetness, size consist, density).-the chemical composition of the material being sampled -the location of the sample point and the space available for installation, extraction, reduction where necessary, secondary sampling, and return of the sample rejects downstream.-whether the process to be sampled is in an existing plant or one yet to be designed and built.-ease of access for servicing and maintaining the equipment.-whether the sampled material must be collected continuously or intermittently.-whether an existing sampling method is likely to be adequate or whether a new technique has to be developed."

Jan 1, 1989

By F. Hassani

This Paper describes a sudden spill of rock waste used for backfilling from a waste pass at one of the underground mine in Canada thus causing a major failure/accident. The mine operator immediately launched a detailed investigation to understand the causes of this accident and develop procedures to prevent any recurrence of such events in future. The investigators from McGill University were invited to collaborate with the engineers at the mine to examine this accident. The events leading to the accident were studied and appropriate measurements were taken and samples of the waste material was collected for further test and analysis. The field visit and the interview of the witnesses allowed a detail documentation of the events. The sequences of events related to the incident together with the experimental results obtained in the course of the investigation is detailed. The waste material was characterised in the laboratory with regard to its behaviour in the presence of water. This information is then discussed and the failure mechanism involved in this accident is identified. The full recommendation as well as the immediate operational measures implemented by the mine to prevent future occurrence of such events are discussed and presented.

May 1, 2003

By Dolea Gabriel Gheorghe

In the present paperwork is proposed an economical-mathematical model (fuzzy) that aims optimize the technological variants of the mechanized coal face. By fuzzification, the issues to solve become more flexible and allow the decision maker to acquire more variants for the functions objectively established. The description of technological solutions is carried out by a set of controllable variables of "category" type by which the type of the machinery is defined within the frame of the actual geological & mining conditions. In the paperwork are used concepts of "successions graph" and "matrix of compatibilities"; with their help a methodology to choose between different technological variants of coalfaces is proposed. It treats the problem of developing the functions that express the membership degree in vague concept. In the end it is presented an assessment procedure for the technological variants of mechanized coal face.

Oct 1, 2009