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By P. E. Hand

Coal is a complex heterogeneous commodity that can be mined in a number of ways and needs to be processed to a homogeneous quality that satisfies the customer?s requirements, while attempting to maximize revenues. Only a small proportion of coal is suitable for metallurgical use. Export coals cover a wide range of qualities and some coals can be used optimally in the raw state for energy production. Critical quality parameters vary and can be a combination of heat value, ash, volatiles, sulphur, phosphorus, sizing, amongst others. The level of beneficiation is generally dictated by the washability of the coal, mining contamination, and the target product quality. The steps in the coal chain covered in this paper comprise exploration, mining selections, production, the washing process, and product delivery. Many points of sampling are needed to maximize yield at the correct quality, and some of these will be described in the paper. Keywords coal chain, coal beneficiation, sampling.

Jan 1, 2014

By R. M. Lamya

The leaching behaviour of nickel?copper matte in an acidic?copper sulphate solution during the repulping stage at Impala Platinum Refineries has been studied. The base metal recovery process consists of a matte repulping stage prior to a series of pressure leach stages. Therefore, the repulping stage is basically an atmospheric leach stage in which the matte containing mostly Niand Cu is leached in copper-spent electrolyte from the tank house, resulting in dissolution of nickel and precipitation of almost all the copper. To understand the nature of the leaching process during this stage of the operation, the effects of temperature stirring rate and matte particle size on the rate and extent of base metal dissolution and copper rejection from the solution have been investigated. The leaching mechanism of the matte in the investigated system is alsoproposed.

Jan 1, 2006

By Emad Iskander

The seepage forces generated around pressurized water tunnels in rock are investigated using the analysis tools of geomechanics. The theoretical background of the two-phase material behavior is explained and the equations of motion and continuity are presented. Applications on two case studies typically occurring in practice deal with the required minimum rock cover for a pressurized tunnel and the separation between two tunnels carrying different heads. The rock mass behavior as described by the Mohr-Coulomb and Hoek-Brown material models is investigated by numerical analyses and the results are compared. The effect of key material parameters on the safety factors and the associated modes of failure is discussed.

Jan 1, 2008

The Electricity Generating Authority of Thailand (EGAT) Mae Moh coal mine is an open-cut coal mine in Thailand that produces about 16 Mt of lignite annually to generate 2400 MW of electricity. The surface mine pit covers is 4 km by 7 km with mining depths ranging up to 260 m. A large pit slope is formed with the progression of the mining operation. However, massive slides in the pit slope occur often due to the existence weak planes such as faults and bedding, and the weak mechanical properties of the rocks. Hence, 200 m to 300 m boundaries of rock block including coal seams are left in front of faults in order to prevent slides and maintain the stability of the pit slope. As a result, there are significant coal reserves beneath the abandoned area along the pit slope. Moreover, the mined coal seams are very thick and their thickness range from 15 to 30 m.This paper discusses the application of multi-slicing highwall mining system with stowing to this very thick coal seam left around large pit slopes by means of numerical analysis.

Dec 6, 2010

Fines and unnecessarily small rock fragments are created by as many as four identifiable breakage mechanisms which operate close to the charged section or sections of the blasthole. The peak blasthole pressure (Pb) should not exceed that value at which the rock starts to fail in compression. Excessive Pb values can be prevented by carefully selecting:1. the composition, density and/or diameter of the charge, and2. the initiation/priming system.The percentage of fines increases with:1. increases in the charge diameter:blasthole diameter ratio, burden distance, blasthole diameter, effective sub-drilling and size of blast, and2. decreases in blasthole spacing, stemming height and the length:width ratio of the blast block.Decked charges tend to reduce the percentage of fines.Excessive fragmentation is more evident in buffer blasting and sinking cut shots than in blasts fired to a clean free face. Initiation sequences which give effective burdens considerably less than drilled burdens encourage the minimization of fines, as does an inter-row delay time which promotes good progressive relief of burden.The wastage of explosive energy in creating fines is most pronounced where fully-coupled, energetic charges are fired in weak and/or highly porous rocks. This is especially so where forward movement of the strata is impeded by buffer rock, excessive burden distances and/or inadequate inter-row delay times.

Jan 1, 1979

By Javaid M. Alvi

This paper is an attempt to outline the emergence of Augered Cast-ln-Place piles as one of the more economical types of foundation for supporting high-rise buildings and heavily loaded structures recently constructed in the flood plains in and around the Greater Pittsburgh area. To understand the process of selecting foundation types, it is important to understand the general geology of the area and past construction activities that have taken place in the flood plains, especially along the riverbanks, during the last century. The first part of this paper presents a brief description of the general geology of the area; the second part of the paper concentrates on the historical evolution of the use of deep foundations and selected case histories; and the last part presents the results of load tests on large diameter Augered Tremie Concrete (ATC) Piles placed in sandy alluvium which suggests a much larger load-carrying capacity of these piles and also provides an insight into their future application. 2.0 GENERAL GEOLOGY 2.1 Soil Overburden Most of the high rise buildings in the Central Business District as well as along the North Shore and South Side of Pittsburgh are situated in the flood plain at the confluence of the Allegheny River and the Monongahela River where their combined flow forms the Ohio River. The flood plain consists of unconsolidated deposits of Quaternary age that overlie the bedrock of Pennsylvanian age. These deposits are called alluvium or valley fill, and include moderately to poorly sorted clay, silt, sand, gravel and some boulders. Their thickness varies from zero at the edges of the valley to about 80 feet towards the rivers (Figure 1).

Jan 1, 2001

By Yoshinori Iwasaki, Shosei Serata, Yutaka Mochida

A new comprehensive insitu instrumentation technique named this RCC Method has been developed for rapid assessment and improvement of the structural stability of underground openings. When applied to tunnel construction, the degree of present and prospective safety of underground openings can be determined in quantitative terms within 10 to 20 minutes of microcreep observation. When applied to mining, roofs and floors can be stabilized by controlling the stress conditions. This stress control method has eliminated the need for intensive roof bolting and extensive floor renewal in all cases where it was applied. Use of this technique is illustrated by field examples from the Seikan Undersea Tunnel of Japan and deep potash mining in Canada. NEW INSTRUMENTATION TECHNIQUE: THE RCC METHOD Failure problems in underground excavation usually arise in weak non-elastic grounds where conventional rock mechanics theories of elasticity are not only useless but also misleading. Presently, discontinuity planes in the ground are being considered a factor in assessing these failure problems, and while this development is interesting academically, it is not of much use in actual excavation work, where it is nearly impossible to identify and quantize all existing planes of discontinuity. Even if such an extraordinary task could be accomplished at an underground excavation site, effective use of the data would be difficult and impractical for rapid excavation work, with the possible exception of rare cases of ideally elastic ground.

Jan 1, 1976

Train services through the Channel Tunnel linking Britain and France where scheduled to be fully restored in February 2009 following several months of repairs after a major fire in the tunnel on Sept. 11, 2008. A lorry caught fire on a shuttle train carrying heavy goods vehicles bound for France through the 50-km- (31-mile-) long northern tunnel. The fire, that spread to other vehicles, raged for about 16 hours. The extreme temperatures of up to 1,000º C (1,832° F) caused extensive damage to about 600 m (2,000 ft) of the 7.6-m- (25-ft-) diameter tunnel?s concrete lining, approximately 11 km (7 miles) in from the French entrance. The Channel Tunnel operator, Eurotunnel, awarded the repair con-tract, estimated to be between ?50 to 60 million, to a consortium of Freyssinet, Eurovia Travaux Ferroviaires (ETF) and Vinci Energies. Freyssinet was appointed to look after the civil engineering works, while ETF would be responsible for track and overhead wire restoration and Vinci Energies responsible for other equipment. The technique of hydrodemolition, which uses high-pressure water jets to remove concrete from various structures, was specified as the method to remove the fire damaged concrete. Freyssinet subcontracted the concrete removal to the specialist hydrodemolition and industrial cleaning contractor Philip Lasserat.

Jan 1, 2009

By S. R. Dindarloo

Although blasting is one of the most widely used methods for rock fragmentation, it has a major disadvantage in that it causes adjacent ground vibrations. Excessive ground vibrations can cause a wide range of problems, from nearby residents complaining to ecological damage. Prediction of blast-induced ground vibration is essential for evaluating and controlling the many adverse consequences of surface blasting. Since there are several effective variables with highly nonlinear interactions, no comprehensive model of blast-induced vibrations is available. In this study, the support vector machine (SMV) algorithm was employed for prediction of the peak particle velocity (PPV) induced by blasting at a surface mine. Twelve input variables in three categories of rock mass, blast pattern, and explosives were used for prediction of the PPV at different distances from the blast face. The results of 100 experiments were used for model-building, and 20 for testing. A high coefficient of determination with low mean absolute percentage error (MAPE) was achieved, which demonstrates the suitability of the algorithm in this case. The very high accuracy of prediction and fast computation are the two major advantages of the method. Although the case study was for a large surface mining operation, the methodology is applicable to all other surface blasting projects that involve a similar procedure.

Jan 1, 2015

By João Carlos Jânio Gigolotti

O avanço tecnológico tem gerado demanda crescente por materiais que possam ser utilizados em alta temperatura e ambientes oxidantes, o que inclui ligas intermetálicas MR–Si–B (MR = metal refratário) com estruturas multifásicas. Assim, este trabalho teve por objetivo estudar a microdureza de ligas do sistema Hf–Si–B na seção isotérmica a 1600ºC, na região rica em Hf. Ligas Hf–Si–B foram fundidas com lâminas de Hf (min. 99,8%), Si (min. 99,998%) e B (min. 99,5%), em forno a arco e tratadas termicamente a 1600 ºC em atmosfera de argônio. As relações de fases nessas ligas foram identificadas por difração de raios-X e por contraste, em imagens obtidas via microscopia eletrônica de varredura no modo elétrons retroespalhados. As ligas tiveram sua dureza medida pelo método Vickers (microdureza) com cargas de 0,05 kgf e 0,2 kgf e tempo de aplicação de 20 s. Os resultados, obtidos da média aritmética das medições realizadas nas regiões heterogêneas de cada liga, mostraram uma dureza média de 11,08 GPa, com pequeno coeficiente de variação de 3,8%. Os boretos HfB2 (19,34 GPa) e HfB (11,76 GPa) apresentaram dureza mais elevada que os silicetos Hf2Si (8,57 GPa), Hf5Si3 (9,63 GPa), Hf3Si2 (11,66 GPa), Hf5Si4 (10,00 GPa), HfSi (10,02 GPa) e HfSi2 (8,61 GPa).

Aug 17, 2017

PERSPECTIVE ?Natural resources exploration, extraction and beneficiation is complex and challenging: ?Input costs rising, complexity increasing, rising stakeholder management needs, regulatory compliance issue, etc. ?With increasing costs and complexity of managing operations are we simply getting less bang for our buck?

May 1, 2013

By D. A. Douglass

This report describes the tri-n-butyl phosphate extraction of cerium (IV) from a sulfate leach liquor prepared from a bastnaesite concentrate as well as from pure eerie nitrate solutions. The work was done on a laboratory scale using separatory funnels. Extraction from pure cerium solutions entailed no great difficulties; however, extraction from the bastnaesite solution proved more difficult, mainly because of the inhibiting effect of the sulfate ion. Despite this, procedures were developed for obtaining good single-state cerium extraction (95+ percent) and a high-purity product (99+ percent), although the maximization of both cannot be achieved simultaneously. This necessitates a compromise in any extraction scheme.

Jan 1, 1959

By Daniel Su

This paper describes recent ground control challenges encountered at the longwall recovery areas of one of Bailey Mine?s two longwall faces and the proactive measures taken by CONSOL management and engineering to mitigate them. The challenges derived primarily from the following causes: (1) irregular roof coal and draw slate thickness, (2) presence of thick sandstone at the recovery area and extremely weak rocks below the sandstone, (3) close proximity to a regional anticline, (4) low shield set pressure and tip load, and (5) ineffective primary roof support that led to progressive failure of the headgate roof. The presence of the anticline contributed to extensive fracturing of the sandstone. Excessive pot-out in advance of the shields frequently occurred near mid-face due to the presence of thick draw slate and irregular roof coal near the recovery area. This, in turn, resulted in face heights that exceeded the maximum reach of the shields. Subsequently, during longwall meshing, when the advance rate slowed considerably, fractured sandstone would often break loose, causing the shields to yield, thereby reducing the height and inhibiting shearer movement. To improve the headgate and face conditions within the longwall recovery area, several actions were taken, including: (1) assessing site-specific roof geology by conducting in-mine roof coring around the recovery areas and by mapping immediate draw slate and roof coal thicknesses within surrounding entries, (2) increasing pump pressure and thus shield set pressures (3) diligently monitoring shield set pressures and longwall extraction horizon, (4) installing additional cable bolts and roof screening to prevent progressive failure of the immediate headgate roof, (5) fully-grouting supplemental cable bolts to improve headgate support stiffness, and (6) gluing the headgate roof within the recovery areas with polyurethane. As a result of these collective efforts, longwall recovery delays at Bailey Mine were reduced from 21 days in 2006 to nearly zero in 2009.

Jan 1, 2009

By V. Kecojevic

Environmental and economic costs related to equipment fuel consumption and carbon dioxide (CO2) emission present a substantial challenge to the mining industry. Haul trucks are an integral part of the overall surface mining system and they consume a substantial quantity of fuel. Consequently, they produce a significant amount of CO2. The objective of this research is to (i) establish a mathematical relationship among a truck?s fuel consumption, power and engine load factors and (ii) determine the amount of a truck?s CO2 emission and the associated cost that may arise from potential CO2 legislation. In order to achieve these objectives we have considered original equipment manufacturer (OEM) haul trucks, commonly used in surface mining operations. The research presented here may be used by mining professionals to help determine the cost and environmental burden of the trucks? application, and efficiently manage energy consumption.

Jan 1, 2011

By G Tripp, G Lorusso

The Velvet gold orebody (153 Koz Au) is located near the Kanowna Belle gold deposit in the Boorara Domain of the Kalgoorlie Terrane, a subdivision of the Archaean Eastern Goldfields Superterrane (Swager et al, 1990). Gold mineralisation at Velvet is hosted within an intrusion of intermediate composition that broadly follows a sub vertical hanging wall splay of the Fitzroy Shear Zone.Velvet was discovered in 2003 during an underground exploration drilling program targeting potential strike extensions to the Kanowna Belle deposit. Diamond drill hole KDU1595 returned a downhole intercept of 36 m grading 4.6 ppm Au approximately 500 m west of the deposit and at a vertical depth of 700 m below surface in the immediate hanging wall of the primary Kanowna Belle host structure, the Fitzroy Shear Zone. Subsequent drilling completed following the initial discovery, from both surface and underground collar positions, failed to replicate this result.In 2014, KDU1595 was resurveyed gyroscopically and the mineralised intercept correctly located. Additional drilling was undertaken to follow-up the repositioned discovery hole. Challenges included poor drilling angles through the Fitzroy Shear Zone, excessive deviation during drilling and the unknown geometry of the target. Navigational drilling helped to successfully penetrate the Fitzroy Shear Zone and in April 2015, drill hole KDU3234 returned a significant downhole intercept of 45 m grading 5.6 ppm Au.Additional drilling success resulted in a decision to develop a 600 m drive to serve as a dual-purpose access for further exploration and mining. This was a potential risk considering that the orebody geometry was unknown and all significant drilling results were clustered within a 50 m × 50 m panel. Development commenced in June 2015 and the first ore cut taken in April 2016. Geological mapping and structural interpretation, together with multi-element and spectral analysis of drill samples has enabled several other target areas to be identified for exploration. The Velvet mining area is critical to continued production at Kanowna Belle. Geological understanding must advance as mining progresses to ensure continued resource growth and optimal extraction of reserves.CITATION:Lorusso, G, Rogers, J and Tripp, G, 2017. Velvet underground exhumed – discovery and development of a new mining front at the Kanowna Belle gold mine, in Proceedings Tenth International Mining Geology Conference 2017, pp 169–174 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 20, 2017

Of late there have been various papers published on this subject by various authorities, in which certain definite factors influencing slime settlement have been brought forward. As the principles set forth by these writers are of great interest, and have, in most cases, been generally accepted, the author will review them in the hope that by discussion some more knowledge may be brought to bear on many points connected with the subject.The definition of slime at the present time is not a standard one, and varies according to different authorities, some defining slime as ore crushed to such a fineness that it will pass through a screen of standard size, say 150 or 200-mesh, in water (1, 2);others as that part of the finely-crushed material which is in the physical condition which causes it to remain in. suspension in water, and possesses pr?perties which render it almost unleachable (3). Authorities seem divided on this point, but of late American writers seem to prefer the former definition. On the contrary, B L Gardiner describes slime as a mixture of small particles of crushed ore of varying sizes which, when mixed with water, tend...

Jan 1, 1912

By Ron Bromenschenkel

The State of California, Department of Transportation is currently retrofitting a major interchange near the San Francisco area. The project is located in a highly traveled area of Oakland with light rail commuter service near many footings. Over 600 micropiles are being used in conjunction with CIDH piles for footing stabilization. A specially designed Soil Nail pile will support footings for a new light rail utility structure. Pile testing features in this contract serve as points of interest for future foundation designs. The presentation focuses on substructure issues of this incterchange retrofit. Both design and construction considerations will be covered. Design Considerations: ? Project Description ? Structure inadequacies ? Design criteria ? Design contraints ? Retrofit strategy ? Consultant analysis ? Pile Designs and Test Sites ? Contract Specifications ? Construction Plan and Cost

Jan 1, 1998

By Brad Thrall, Howard Bradley, Michael Samuels

"LOCATIONViceroy Minerals Corporation owns and operates the Brewery Creek heap leach gold mine located approximately 55 kilometers northeast of Dawson City, Yukon Canada. Dawson was home of the Klondike Gold Rush 100 years ago. Upon startup in November 1996, the Brewery Creek Mine was the northernmost operating heap leach gold mine in North America and one of the most northern in the world. Located at 64"" 02' latitude, the mine is less than 300 km south of the Arctic Circle. Access to the mine is available at Kilometer 14 of the Dempster Highway, linking Inuvik, NWT and the Klondike Highway, 40 kilometers east of Dawson City. The immediate vicinity is the only part of Canada not glaciated in the Wisconsin advance, which has resulted in an oxide ore deposit due to approximately 80,000 years of weathering - an area unique in Canada.DESCRIPTION OF OPERATIONSIn order to utilize heap-leaching technology successhlly in an extreme northern climate, a number of design features were incorporated into the process flow sheet to operate on a year round uninterrupted basis. Winter temperature may dip below minus 50 ""C, demanding an approach to mining and leaching that is different from heap-leach operations in more temperate climates. Because of the severe winter temperatures, the mine operates approximately 2 10 days per year, while the leaching process is continuous on a year round basis. Run of mine ore (ROM) is placed on the heap beginning in mid April until late October. Overall gold recovery is projected to be 78% over a 325 day leaching cycle with annual production levels of 2.3 million tonnes of ore placed on the pad, with an average of 75,000 ounces of gold recovered per year. The recovery process utilizes conventional sodium cyanide leaching, carbon adsorption, high pressure stripping, thermal reactivation and acid washing, and on-site smelting.HISTORYFollowing a comprehensive governmental and public review of the proposed project, a Class A Yukon Water license was issued in August, 1995. Construction started in 1995 and leaching commenced in October 1996.A Socio-Economic Accord with the Tron Dek Hwech'in First Nations provides for employment, contract, and scholarship opportunities for First Nations citizens."

Jan 1, 1999

By William D. Monaghan, Michael A. Trevits

Over the period 2000 to 2003, roof falls have accounted for 4 to 14% of the fatalities in underground mining operations. The National Institute for Occupational Safety and Health (NIOSH) is conducting research to reduce the frequency, exposure, and risk of these events through an ongoing program of field and laboratory studies. One area of research involves the evaluation of polyurethane grouting technology that is commonly used to stabilize fractured mine roof strata. Concurrently, NIOSH is conducting work to evaluate the application of ground penetrating radar for advanced delineation of problematic mining areas. In this study, NIOSH partnered with Sub-Technical, Inc. who injected a polyurethane grout (also known as glue) into a roof area of NIOSH’s Safety Research Coal Mine. The mine roof area was scanned using ground penetrating radar technology before and after grout injection in an attempt to determine the extent of grout infiltration. A comparison of the pre-and post-grouting radar records showed a significant change at a mine roof depth of about four to five feet. The interpreted radar records were then compared with drill core information, borescope evaluation of roof-bolt holes in the study area, and underground observations. At this site, the interpretations of the radar records correlated with data obtained from the core holes, borescope evaluations and underground observations. This study showed that ground penetrating radar technology can be a useful tool for detecting changes in mine roof due to the injection of the grout.

By Arun .. J. Basu

The paper introduces Intelligent Air Management (IAM) as the core activity of M&I Group of Companies (M&I) for providing a total solution to any air management problems for mining and mineral processing operations implementing a comprehensive systems approach through a world-wide network of strategic alliance partners and in-house engineering team and manufacturing facilities in Mississauga, Ontario, Canada. Recommendations for energy-efficient ventilation in a vibration and noise free environment are made with the patented and innovative solutions supported by extensive computational fluid dynamics (CFD) studies. The solution scope extends from an intelligent and integrated exhaust silencer to a complete ventilation sys-tem solution including inlet and outlet control design and ducting for diffusers and silencers.

Apr 1, 2005