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By Bruno Bussière

Acid Mine Drainage (AMD) from mine wastes is one of the most environmental challenge currently facing the mining industry. AMD is the result of the natural oxidation of sulphides exposed to air and water. When mining wastes have the potential to produce AMD, these reactive wastes have to be managed to meet existing environmental regulations. The LTA site (property of Barrick Gold Corp.) contains sulphide tailings that have the potential to generate AMD. The closure option Barrick selected was to construct a multilayered cover with capillary barrier effects (CCBE). The main objective of this CCBE is to prevent the production of Acid Mine Drainage (AMD) from the tailings stack covering an area of approximately 60 ha. Since its construction in 1996, the cover has been monitored to evaluate its performance. Two of the measured parameters are volumetric water content and matrix suction. This paper presents some of the main results from the monitoring program that started seven years ago. The results show that the cover is largely able to maintain a high degree of saturation (greater than 85%) in the moisture-retaining layer. The actual performance of the CCBE on the flat surface of the 60 ha site is even better than expected at the design stage. The area that requires more specific attention with the LTA cover is the influence of slopes that can reduce the performance of the CCBE during dry periods. However, these effects seems to be local and do not significantly affect the overall performance of the CCBE to mitigate the production of AMD at the LTA site.

May 1, 2003

By Pierre Beaudoin

"This paper deals with the repairs made on two damaged mills. It investigates briefly the causes of the damage, explain its nature and the design of the repair. It explains the detrimental effect on operation and the solutions implemented to reduce them. Finally, to review the follow-up required for such repairs. LOCATIONThe Holt McDermott Mine is located 75 kilometers Northeast of Kirkland Lake and 30 kilometres west of the Quebec border in Northeastern Ontario. The town of Kirkland Lake is located approximately 500 kilometres north of Toronto. HISTORYThe discovery of gold in Holloway Township dates back to early 1920. In 1984 Barrick Resources, which amalgamated with Camflo Mines, acquired more claims on the property and initiated an extensive drilling program. By 1985, the drills indicated reserve increased to 2,500,000 tonnes grading 6.8 g/mt. In 1986 a production decision was made and in 1988 the mine was officially opened.As of December 31, 1998, 4,691,507 tonnes grading 5,66 g/tonnes have been milled from 4 ore-bodies. The mill started up in June 1988."

Jan 1, 2001

By W. R. Hopkins, J. A. Davis

"This paper presents a discussion of the mechanisms by which aerosols of the process electrolyte are entrained into the breathing environment of copper, Zinc and nickel eIectrowinning tankhouses. Literature outlining the health effects associated with worker & posure to the acidic and metallic contaminants found in the airbome aerosols is summarized and compared with existing North American regulations.A brief review of the existing technologies for the source reduction of these aerosols is presented. This paper outlines the industry experience with use of covers, balls, beads, shapes, fixtures and chemical surfaetants. Each of these devices is ranked according to its effusiveness in the process in which it is used, and rated according to its operator acceptance.The various forms of existing in-plant ventilation systems are reviewed with a discussion of their relative merits and effectiveness. Actual experience is related, detailing the methods of testing for ambient contaminant levels in a variety of tankhouse environments. Guidelines are provided for the site and process specific criteria which govern the selection and ultimate effectiveness of a particular form of ventilation system.Finally, actual project experience is cited in which hydraulic modelling is used a design tool in tankhouse ventilation design. These projects include the upgrading of existing traditional ventilation designs, and the ''grass roots"" design of a more efficient aerosol source control system to be used in high altitude, cold weather sites."

Jan 1, 1994

By A. Ghahreman, M. Oliazadeh

"Heap leaching is an attractive process for low grade deposits where the metal content of ore does not justify the high cost of milling and agitated leaching. In general, the heap leaching capital cost is low, construction is rapid, and production costs are low. The primary disadvantage of heap leaching is low recoveries (typically 65% of agitated leach recovery); thus, recovery improvements could convert more lower-grade deposits into minable reserves. This will also allow to process primary sulfide ores and result in a dramatic expansion of the technology, as ~80% of total ore types are sulfidic in nature. The old gold operations tailings are another massive source of low-grade gold material that can be retreated by the heap leach process. The major parameters affecting the recovery rates are ore characteristics (mineralogy, particles size of metal and host minerals, ore permeability), and operational conditions (segregation of ore, compaction, leach cycle time, lift height, and solution application rates). The design of a percolation leach process is based on a limited number of coarse ore bottle roll and/or column tests under ideal conditions. The economics of the projects and engineering design of the process facilities are developed based on the bench scale test work results and the application of the conventional engineering scale up factors. This paper will deal with the parameters affecting the HL efficiencies and focus on the potential improvement of gold heap leach recoveries. This would include design of heap leach operation and evaluation of processes such as fine crushing and bioleaching.INTRODUCTION Gold heap leaching is a hydrometallurgical process designed to treat amenable low-grade gold ores that contain typically 0.5 to 1.5 g/t gold (Marsden and House, 2006; Wong Wai Leong and Mujumdar, 2010). Ore is stacked by various types of equipment on an impermeable barrier, and a sodium cyanide solution is applied to the surface of the stacked ore. Gold, silver, and other metals contained in the ore are dissolved to various degrees by the cyanide application, as it percolates downward through the stack of the ore. The pregnant leach solution (PLS) is then collected at the bottom of the heap. The PLS is then sent to the gold recovery plant where the metals are extracted. The barren leach solution (BLS) is then reapplied to the top of the pad. Ore is placed on a pad or previously leached lift by various means, including ramp conveyor belts, radial-arm and self-leveling stackers, and trucks. Once trucks are used to construct the pads, the pad can be compacted and hence the pad should be graded and ripped or scarified (roughened up) with wheeled or tracked equipment to produce shallow cuts to increase surface area exposure to the leachate."

Jan 1, 2019

By Mark Ferra

Flotation is used in mining to produce concentrates of copper, gold and several other valuable ores. In 2017, a copper mine near Globe, Arizona improved their rougher cells productivity using technically advanced electro-hydraulic actuators in the flotation process by enabling excellent tank pulp level process stability. The new actuators controlled the dart valve position to allow pulp to leave the cell. Tank cell pulp level can change due to feed and discharge fluctuations from neighboring tanks. When traditional pneumatic actuators are used, they have sluggish response times and overshoot due to the inherent physical property of air being compressible. Electro-hydraulic actuators have the benefit of hydraulic stiffness to deliver accurate and repeatable (0.1%) dart valve positioning. The froth layer has more opportunity time to maximize mass transfer into the launderer. The results are an increase in copper recovery by 2-4%. INTRODUCTION In 2013 there was an international flotation technical conference well attended by respected flotation specialists for both mining companies and academia. During the technical session a leading metallurgist was discussing pulp level measurement and said that when he was on the cell deck he stated, pneumatic actuators air cylinders stroking up and down. The presenter then claimed with confidence that "I listened to actuator move so the pulp level in the tank was being controlled!" No one questioned his assumption and I can assert that the audience was quite technical and not shy in their critiques of speakers. The flotation community simply believed that the existing pneumatic technology was enough with no alternative. Having a stable flotation cell pulp level is critical to effective copper recovery. Controlling pulp levels in flotation cells is a complex task that includes modulating dart valves in each cell. The use of REXA Electraulic actuators will decrease the process dead time and maintain froth height in a controlled manner, especially from pulp slurry volume fluctuations from neighboring cells. By reducing flotation cell pulp level tank height variation, a copper mine in Arizona has realized a 2-4% recovery improvement by increasing the froth transfer to the launderers in the rougher cell circuits compared to pneumatic actuators. This paper examines the benefits of using an electro-hydraulic actuator to ensure proper pulp level control and reduce the process operational cost. It will focus on actuator positioning the dart valves to maintain pulp level setpoint at a copper mine in Arizona.

Jan 1, 2019

By Graham E. Brown

Since the beginning of time, people later to be known as engineers and architects have strained to create methods whereby they could improve technology to assist them in their various fields of endeavour. Some of these improvements would be the change from linen paper, french chalk and ink pens to drafting film , mylar an d pencil for the production of drawings, the drafting machine in lieu of the tee and set squares, even tap e to attach drafting media to the board instead of thumb tacks and man y, man y more. All of these taken individually are insignificant but combined evolve to the current state-of-the-art in the computerized engineering environment. Ten years ago the major topic o f conversation was the hand-held calculator which for a cost of around $150 would give most trigonometric functions. Today the equivalent calculator can be purchased for around $25, is about one third the size, and if inflation were included over the last ten year s the item should cost around $550 in today' s dollars, it can be seen that tremendous advances not only in the technology but also the cost saving. The following paper is intended to outline some o f the significant aspects o f the latest technology in the computerized engineering office namely Interactive Graphics Systems.

Jan 1, 1985

By D. Cronin, A. Plumtree, A. Hosseini

"Crack in corrosion (CIC) linepipe defects are hybrid defects not directly addressed by existing assessment methods. To investigate the collapse pressure of these defects, CIC defects were formed in 508 mm (20 in) diameter, 5.7 mm thick API X52 linepipe. These defects were 200mm long and varied in depth from 3.0 to 3.8 mm. The respective failure pressures decreased from 14.3 MPa for the plain pipe to 7.9 and 6.2 MPa respectively. A standard FAD method was applied to evaluate these defects as equivalent length and depth cracks, predicting the rupture pressure conservatively by 18% on average. However, when assessed as equivalent cracks with a reduced wall thickness corresponding to the corrosion depth, the predicted collapse pressures were more accurate, approximately 14% conservative on average.INTRODUCTIONPipelines are a safe and efficient method for transporting high volumes of oil and gas. However, aging pipelines may experience defects, such as cracks or corrosion. Present approaches include detection, assessment and repair of defects before they may become critical to the integrity of the line. There are different codes and standards for assessing pipeline defects, depending on the type of defect, with API 579 (API, 2000) being the most common code for the assessment of cracks in oil and gas pipelines . Corrosion is commonly assessed using RSTRENG (Kiefner & Vieth, 1989). Other methods such as the Finite Element method and the CPS method (Cronin & Pick, 2002) may be used for crack and corrosion, respectively.At present, there is no specific method or procedure for assessing crack in corrosion (CIC) defects, and as a consequence there is a need to provide an assessment and evaluation of the integrity of these defects in order to determine the requirements for defect repair or hydro line testing. Hence, the goal of this study was to provide guidance for the assessment of CIC defects for linepipe.CRACK IN CORROSION DEFECTS (CIC)Significant amounts of corrosion and cracking are not generally found together (Hosseini, 2010). However, a new hybrid defect including cracking within corrosion (CIC) has been identified in operating pipelines. In this case, cracking coincident with corrosion (schematic shown in Figure 1) provides the motivation for the current study."

Jan 1, 2012

By A S. Leitch

This paper is based on the accident prevention pro-gram carried out in the coal mines of Alberta. It defines the role of the Alberta Mines Branch and of The Work-men's Compensation Board, and relates how a safety pro-gram was initiated. The formation of the Alberta Class 1 Mining Safety Council is also described. The responsibilities of both management and the individual worker are then outlined, and the main features of a successful accident prevention program are delineated. T HE purpose of this paper is not to repeat generalities and platitudes about industrial safety, but rather to relate the experience of Alberta coal mines during the past number of years in their efforts to keep accidents to a minimum. It has been learned from experience that many basic principles are as sound today as they were 20 years ago. How-ever the complexities of modern mining methods and the modern man or miner have created problems that did not exist then.

Jan 1, 1964

By Y. H. Hatzor

"This is an extended abstract for a keynote lecture delivered by the author during the 2015 ISRM congress in Montreal on the application of the numerical discontinuous deformation analysis (DDA) method in rock mechanics practice. Due to the large scope of the topic this lecture will focus on studies performed by the rock mechanics group at Ben-Gurion University, alone or in collaboration which other research groups, and is not intended to provide a comprehensive review of everything that has been done on the subject worldwide during the past two decades. A forthcoming textbook (Hatzor et al., in preparation) will attempt to provide such comprehensive coverage.DDA has been developed by Dr. Gen-hua Shi while he was doing his PhD studies under the supervision of Professor R. E. Goodman at U. C. Berkeley (Shi, 1988). Dr. Shi has invented a new numerical discrete element method which provides a solution for dynamic deformation of block systems, hence its applicability to rock mechanics practice. The method is similar in essence to the finite element method in its implicit formulation of the time integration scheme and where in every time step the minimum potential energy of the entire system is sought, but here every element is a finite block with six degrees of freedom. The blocks are assumed to be stiff (simply deformable) so that most of the energy is consumed by slip along pre-existing discontinuities, the frictional resistance of which is assumed to obey the Coulomb-Mohr failure criterion for rock joints. The greatest advantage of DDA over alternative numerical discrete element methods is its robust area (volume) integration which ensures great accuracy even when the blocks are of irregular shapes, including non-convex blocks which may contain holes. The greatest disadvantage is the necessity to solve in every time step very large matrices of unknowns, imposing great CPU demand when the block system involves a large number of blocks. Another disadvantage is the sensitivity of the solution to the choice of the penalty parameter which is implemented in DDA in the form of stiff springs that are attached to contacts once detected automatically.The inherently dynamic formulation of the DDA method lends itself to solution of dynamic problems in rock mechanics. Dynamic analysis with DDA can be performed in different ways corresponding to different rock mechanics problems and loading conditions. Three main classes of loading conditions which are relevant to rock mechanics applications are discussed here: 1) dynamic loading of a single bock which rests on a stationary foundation, 2) response of a block to dynamic loading of the foundations, 3) wave propagation through a block system.The most common approach is to introduce the dynamic force to a specific block in an otherwise fixed block system and check the resulting deformation, typically the time dependent displacement or rotation of the loaded block. This approach is particularly useful for dynamic rock slope stability studies when a stability of a specific rock block against earthquake vibrations is in question. The first 2D-DDA benchmark test of this approach was performed by Hatzor and Feintuch (2001) who introduced harmonic acceleration functions into a block which rests on an inclined plane. The analytical solution proposed for this problem by Hatzor and Feintuch (2001) was later generalized by Kamai and Hatzor (2008). The first 3D-DDA benchmarking for this approach was presented by Bakun-Mazor et al. (2012) who studied single and double face sliding of blocks which rest on stationary foundations and subjected to harmonic input acceleration functions."

Jan 1, 2015

By Johnna Muinonen

"The Thompson Mill processes ores from the Thompson and Birchtree Mines. While the Thompson ore has very little magnesium containing gangue, the Birchtree orebody consists of veins of massive sulphide in a rock matrix that contains a high proportion of magnesium silicate minerals. A significant fraction of the magnesium is floatable, which lead to MgO levels varying from 3-11 wt% in the Birchtree concentrate. The magnesium in the concentrate causes a higher operating temperature in the smelter, reducing furnace life.Birchtree ore represented 20-30% of the mill ore receipts prior to October 2003. Since then the fraction of Birchtree ore has increased to 50%. A reduction of the MgO in concentrate to less than 3% in the total mill concentrate was required to allow safe and economic smelter operation.In October of 2002 a miniplant was set up to simulate the Birchtree plant circuit. Several flow sheet modifications were tested that led to a proposal for a circuit having increased cleaning capacity for the scavenger concentrate and a recleaner on this concentrate. Addition of CMC in rougher cleaner feed was also found to be required. The solution was confirmed through pilot plant testing in the mill in December of 2002. A full-scale installation was designed, engineered, and installed between February and September of 2003 with commissioning in September and October of 2003. Target metallurgy was achieved one week after start-up on slurry to coincide with the Birchtree Mine tonnage increase. This paper highlights the development, design and commissioning stages of the project.The new MgO rejection circuit has successfully allowed the processing of Birchtree ores producing concentrate consistently below 3% MgO. In addition, the new circuit increased overall nickel recovery in the mill.INTRODUCTIONThe Thompson Nickel Belt located approximately 700km north of Winnipeg was discovered in the early 1950’s. Inco first produced nickel from the area in 1960. Over the years the mill has processed several ores from different ore bodies in the area. Currently the Thompson Mill processes two significantly different ores from two mines, Thompson and Birchtree. The Thompson ore is a massive sulphide orebody hosted in schist, containing feldspars, quartz and biotite. Thompson Ore is characterized by high nickel recoveries and clean, low MgO containing concentrates (<2.5% MgO). The Birchtree ore is ultramafic and contains a high percentage of Mg-silicates such as serpentine, chlorite, biotite, amphiboles and talc. Some of these Mg-silicates report to the nickel concentrate and prior to commissioning of the MgO rejection circuit the Birchtree nickel concentrate typically contained 5-8% MgO"

Jan 1, 2006

By P. Stantke

Glue, thiourea and chloride are the common reagents which are used in copper electrorefining to achieve fine-grained and smooth copper deposition. While thiourea and chloride are clearly defined chemical substances, glue is a natural product consisting of a mixture of amino acids in different constituent parts. The amino acids are continually degraded in the electrolyte by hydrolysis until they finally become completely inactive. This effect is well-known, largely constant and balanced by the continuous dosing of glue. In contrast, the behaviour of glue in the batch container is not always foreseeable. The glue can become partly or completely inactive by contamination with acid or bacteria, for instance. Usually this is not noticed, and partly or fully inactive glue is added to the electrolyte over a longish period, with the result that the copper growth is significantly impaired. Examples from operational practice show that, with the help of the CollaMat system, partly or fully inactive glue batches can be quickly detected.

Jan 1, 2007

By L. R. Bower

"This paper describes a highly versatile variable speed unit with a torque multiplication feature as a direct replacement for a fluid coupling .The unit is comprised of a modulating clutch with torque converter and lock-up options.The UCD does not start or stop the motor. This is carried out in the normal manner.The UCD continually monitors and rapidly regulates the output speed to the requirement of a set point demand from input signals or a pre-set program with full manual override.The pre-set program can include start and stop ramps, top speed and minimum speed regulation and also mid-speed set point with security for man-riding, etc. Speed variation is from zero to 100% on a constant duty basis.The input signals can be from any source, e.g. belt weigher. load profile bunker probes, mine monitoring system, etc.The UCD when fitted with a torque converter has a torque multiplication feature which automatically provides a starting torque up to two and a half times greater than the full load torque without exceeding the normal motor power levels.IntroductionIt is common practice in the mining industry to drive conveyors, whether they be belt or chain, through a transmission system incorporating a fluid coupling between the driving motor and gear-box .However, there are drawbacks and in an effort to attain a better degree of drive and control, two-speed motors - inverters cycle- converters - hydrostatic drives, etc ., have been introduced."

Jan 1, 1986

By Poul Hansen

"In mid-I986, a world-class mining enterprise was created in British Columbia, bringing together the copper mining operations of Lornex Mining Corporation and Cominco into a new entity, Highland Valley Copper. This paper will focus on the background and rationalef or the formation of this partnership, the resulting operating changes and the productivity and cost benefits expected.IntroductionSince the deterioration of the world copper industry in 1981, the future of the Lomex and Cominco mines in the Highland Valley of British Columbia looked increasingly precarious. Despite the expansion of the Lomex mill complex in 1981 to one of the world&apos;s most cost-efficient copper and molybdenum concentrators, persistent low metal prices had made the remainder of the ore in the Lomex orebody marginally economic and had significantly foreshortened the expected life of the operation.Cominco had acquired the Bethlehem Copper assets in order to consolidate its ownership of the Valley orebody, and was feeding the Bethlehem concentrator with ore from the Valley orebody. In spite of the high grade and free-milling character of the Valley ore, profitability of the Cominco operation was severely restricted because of the limited capacity of the Bethlehem concentrator and its location high on the hillside above the orebody."

Jan 1, 1987

By R. Stach, S. Gola, P. Zgrzebski, K. Soroko

"The future of Polish copper mines KGHM Polish Miedz S.A. will be associated with mining at depth. At present, technologically advanced measures are being introduced to minimize the adverse influence of the environmental hazards on people working underground. Polkowice-Sieroszowice mine is the only mine in Poland where mining takes place in copper and salt deposits. On the basis of the current and anticipated methods of ventilation of a selected ore deposits the paper will analynze a number of solutions enabling planned mining of copper ore deposit, while minimizing the impact of natural aerological hazards in working areas. INTRODUCTION The future of copper ore mining, carried out by KGHM Polska Miedz S.A., will be based on mining from continuously greater depths (Butra, 2015). It is forecast that this will be accompanied by an increasing climatic hazard, resulting from an increase in the original temperature of rocks of more than 45°C as well as gas and geodynamic hazards (Soroko, 2015; Andrusikiewicz, 2015). Due to the safety of underground teams, a need arises to develop methods eliminating the adverse impact of the natural hazards, down to a level enabling the mining activity to be carried out on an industrial scale while maintaining favourable economic parameters. Current depths of the copper ore deposit being developed are effectively verifying the technical methods and measures employed to date for eliminating the natural aerological hazards. Amounts of air supplied to mining areas, with lengthy transport routes, are becoming insufficient for miners’ temperature safety, whereas increasing the power of cooling air-conditioning stations for cooling the air undermines the economic legitimacy. However, along with the temperature hazard, a significant problem at the current depths is an increase in gaseous occurrences in the headings’ areas. The concentrations of natural harmful gases found, even with the values below the permissible concentrations, in the case of limited amounts of air and/or low airflow rates, may pose a considerable danger to the workers. The hazards referred to are currently the major factors determining the advance of headings, above all in mining sections, being the outcome of geological structure and depth of lying of a deposit. However, at the current depths of mining minerals from deposits, room-and-pillar mining systems employed also have a decisive impact on the increase in natural aerological hazards."

Jan 1, 2019

By R. Stauffer, S. Lindsay

"Sherritt Gordon Mines Limited utilizes pressure hydro-metallurgical techniques to recover nickel, copper and cobalt from su1phidic concentrates, mattes and various other metal-bearing materials.A brief description of the nickel refinery operation is given. In the nickel refinery process, an ammonia pressure leach is employed to treat the feed materials to dissolve the non-ferrous metals as their respective ammine complexes. The resulting leach solution goes through a series of steps which removes copper as copper sulphide and further purifies the solution prior to nickel precipitation by hydrogen reduction. The reduction end solution, containing the cobalt which was originally present in the leach solution as well as residual nickel, is treated with hydrogen sulphide. The resulting nickel-cobalt sulphide precipitate feeds the soluble cobaltic ammine process, which separates the nickel and cobalt and recovers the cobalt as a pure powder.A detailed description of the cobalt recovery process is given. Included are the various steps, comprising: acid leaching of the mixed sulphides, solution purification, ammine complex formation and cobaltous oxidation, two-stage nickel precipitation, cobalt conversion and reduction. A brief description of cobalt powder handling is included, along with typical physical properties and chemical analyses of the cobalt product. In general, the purpose of this paper is to describe the present plant practices employed in the recovery of cobalt as a by-product of the nickel refinery operations."

Jan 1, 1967

By L. M. Guayacán-Carrillo, G. Armand, A. Noiret, D. Seyedi, S. Ghabezloo, J. Sulem

"The main purpose of this paper is to analyze the convergence measurements in a drift excavated in the Callovo-Oxfordian claystone. The drift axis is in the direction of the major principal horizontal stress whereas the stress state is quasi-isotropic in the drift’s section. The initial geometry of the drift being circular, the anisotropic character of the deformation is taken into account by assuming that the drift shape evolves in an elliptical shape. The convergence measurement data on six different points around the drift are analyzed to identify the main axes of the deformation ellipse, following the methodology proposed by Vu et al. (2013, Rock Mech Rock Eng, 46, 231-246). Then, using the semi-empirical law proposed by Sulem et al. (1987, Int J Rock Mech Min Sci, 24, 145–154), the convergence evolution is fitted independently for each axis of the ellipse. This method permits to distinguish two effects: the face advance effect and the time-dependent behavior of the ground. The results for the two directions of the ellipse axes show very close values for the parameters describing the time-dependent properties of the ground, the distance of influence of the face, and the extension of the decompressed zone around the gallery. Such model can provide valuable insights for predictions of the convergence evolution in the long-term. INTRODUCTIONDeep disposal of radioactive waste has been studied in France for more than two decades. The French National Radioactive Waste Management Agency (Andra) began in 2000 the construction of an Underground Research Laboratory (URL) with the main goal of demonstrating the feasibility of a geological repository in Callovo-Oxfordian claystone. Several research programs have taken place to improve the knowledge of the rock properties and its response to the excavation progress. The optimization of supports design for long-term behavior is an important point to develop. A network of experimental drifts has been constructed with variations on: excavation method, structure geometry, supports system and orientations with respect to in-situ principal stresses’ directions. In each drift different sections have been instrumented to monitor the convergence evolution and the rock deformation. Continuous monitoring of the excavated zone around the drifts revealed the development of a fractured zone (extensional and shear fractures) induced by the excavation. The extent of this fractured zone depends on both the drift orientation and the in-situ stress field (Armand et al., 2014). Indeed, the fractures distribution has an important influence on the convergence of the drifts."

Jan 1, 2015

By Oy Leuangthong

Red Dog mine is the world&apos;s largest Zn producer. The deposit consists of sulphide ore zones in sedimentary exhalative (sedex) deposits, and is characterized by the presence of multiple metals and multiple ore types. The objective of the case study is to characterize seven different minerals, Zn, Pb, Fe, Ba, sPb, Ag and TOC, within eight different rock types. Geostatistical models were constructed for each variable within the eight rock types, and subsequently assembled to give 40 realizations for six 25ft benches. The stepwise conditional transformation was used to account for the complex multivariate relations. In addition to reproducing the input data, histogram and variogram, the resulting models also respect multivariate relations locally and globally. This paper documents the methodology to construct these models. A thorough validation procedure was implemented. Comparisons with blasthole data show that the conditional simulations and the long-term models agree in expected value. The main advantages of the conditional simulations are (1) the explicit accounting of multivariate relations between the data in model construction, and (2) the ability to quantify variability and uncertainty at any scale. A small exercise comparing the profit from a kriged and a simulated model is also examined. Results show that the simulation approach showed a 3% increase in profit, relative to the conventional estimation approach.

May 1, 2004

High Pressure Grinding Rolls (HPGR) are said to be a good option in new grinding circuits. Due to their low energy consumption compared to other grinding systems such as SAG milling, there is a strong incentive to check their behaviour for certain ore types. With rising energy prices the operation will become even more beneficial in future. As published in the past, the HPGR is claimed to increase the liberation of the valuable mineral component within an ore. An investigation at the research centre of Polysius was conducted to substantiate the liberation behaviour in finish grinding operations. A pilot scale HPGR test unit (POLYCOM MAGRO) with a roll diameter of 950 mm and processing capacity of 80 t/h was used. Grinding tests were completed with a screen and a two stage drying air separation process (SEPOL). Analysis included standard screen analysis, fractional XRF and modern MLA technology. A technique was developed to oppose the amount of produced slimes (resuming bad flotation) against the positive effect of producing high mass fraction at flotation-easy sizes. The paper shows how effective the use of a dry grinding separation could be in terms of production of mass of liberated metal.

Jan 1, 2012

By Son Hye Jin

Abstract ? KHNP is participating in the construction of Nuclear Power Plant both in Korea and UAE. ? We want to improve our construction project management process. ? So we are now developing the process model on nuclear power plant construction management. ? For the effective adoption of this process, we are planning to develop IT system. ? For the first step, we were established the Information Strategy Plan

Aug 1, 2013

By Ron Jessulat

"IntroductionBrunswick Mining and Smelting Corp. Ltd. is a IO 500 tid base metal producer. Development is carried out by Jarvis Clark MJM-21 3-boom development jumbos, using Tamrock E400, 410 and 550 pneumatic drills. Typical drift size is 13 ft by 18 ft with a 12-ft advance per round. Blast holes are 1 ½ in. in diameter while reamed holes are 3 in. in diameter. AN/FO is the principal blasting agent, being loaded by C-I-L model60R intermediate loader. The detonators are NONELS and DETINELS. Sulphide dust explosions occur during blasting when dusts from certain minerals such as pyrite and pyrrhotite are ignited by name from the detonating shots. The result is a secondary unwanted explosion with a characteristic shock wave and name front that are very destructive to mine services such as ventilation ducting, electrical cable, and ventilation control doors.A typical reaction in the Brunswick orebody occurs according to the chemical formula:4FeS 2 + IIOs-2Fe2O3 + 8SO2 + 3458--(Enright , 1988)The hematite (FeO3) is deposited as a red dust in the blast area while the toxic sulphur dioxide gas (S00 contaminates the underground workings . The presence of S02 gas disrupts production until it is purged from the area by the mine ventilation system or dissipates slowly in those areas where the vent ducting has been melted by the name front or torn down by the shock wave.Sulphide dust explosions exact a high economic toll. Direct costs in damaged materials and wages are probably exceeded by the value of lost production and disruption to the mining cycle. In addition, the health and safety concerns associated with sulphide dust explosions cannot be ignored."

Jan 1, 1993