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By Irwan S. Halim

For tunnels in horizontally bedded rock, geologic factors affect the selection and design of the initial supports, including the rock propensity toward parting along bedding and the resulting high potential for rock slabbing during excavation. To evaluate this ground behavior, numerical analyses and results with Mohr-Coulomb, Hoek-Brown, and Ubiquitous Joint constitutive models were used, using the Upper Rouge CSO tunnel in Detroit, Michigan as an example. The different rock models and other geologic considerations are shown to impact the selection of the tunnel initial support and design. This paper emphasizes the appropriate selection of an analytical model based on the site specific geology to achieve an optimum initial support design.

Jan 1, 2008

By D Rubery, C Croker

The Boddington Gold Mine (BGM) is located 120 km south east of Perth, Western Australia. The operation is managed by Worsley Alumina Pty Ltd and mined by contractor Henry Walker Eltin (HWE). The mine has been operating since 1987 with ore extracted from a series of pits along strike. Ore is contained within the basement rock, which is overlain by a cap rock layer and transition zone. Cap rock and basement zones require blasting.As the mine neared completion, a high-grade deposit was discovered within 50 m of an existing Western Power substation and 100 m from the processing mill. The substation provides power to the Boddington area and is a back-up power supply to the city of Perth. Due to the delicate nature of the transformers located at the power station, overhead power lines and the mill, blasting in the area was considered very high risk. As such blasting needed to be controlled for flyrock, airblast and most importantly peak vibration and frequency limits which had the potential to damage the transformers.The mine was due for closure in March 2001. The decision to mine the pit was based on its high grade, ability to be blended with lowering grades from other pits and changing of the processing technique with the expansion. This decision extended the life for a further six months.Due to the high potential risks a detailed risk assessment was conducted by Orica, Worsley and Henry Walker Eltin. The completed assessment and the major design parameters were presented to Western Power for approval. The ability to reduce the blasting risk was focused on limiting of vibration through controlling maximum charge initiated per delay, blast timing and firing direction, and other innovative control measures. OricaÆs SHOTPlan« and Sabrex« computer modelling packages were used to predict the outcome of blasts.The success of this project has opened the doors for other high risk blasting projects, which otherwise may be left unmined.

Jan 1, 2002

By B Kretschmer, G Bartel, B de Villiers, W Watt

"The Nyrstar Port Pirie Smelter, located on the eastern shore of the Upper Spencer Gulf in South Australia 230km north of Adelaide, began operation in 1889 to process lead concentrate from the Broken Hill lead and silver mines. The site still operates an updraft sinter machine, commissioned in 1955, with the product fed into a blast furnace. While sinter plant technology has changed and improved since 1955, development has reached the stage where further enhancements are not possible or economic. High purity lead concentrates command lower margins and for the smelter to remain economically viable a wider range of higher value materials must be treated. The current flowsheet cannot meet this demand. Additionally, community blood lead levels particularly in children below four years of age, are a critical indicator used to measure the site’s environmental performance. The smelter’s environmental licence to operate is dependent on meeting future community and regulatory expectations. To achieve this a major step change in the emission performance of the smelter is required. Since 2008 pre-feasibility work has been undertaken to develop a new flowsheet and business model to allow Port Pirie to operate sustainably into the future. The main requirements were for the smelter to reduce lead and sulfur dioxide emissions that impact on the local environment and community to meet current and future environmental expectations, as well as dramatically reducing current feed constraints and change the business case from a marginal business to a sustainable profitable business. After reviewing all practical options a decision was made to replace the sinter plant with an Outotec Top Submerged Lance (TSL) furnace. This paper describes how the new furnace technology was selected and how it will be integrated into the present flowsheet; the unique funding arrangements that are in place to deliver the redeveloped site; and future opportunities that are associated with the implementation of the new flowsheet. CITATION: De Villiers, B, Bartel, G, Watt, W and Kretschmer, B, 2015. Nyrstar Port Pirie redevelopment, in Proceedings MetPlant 2015, pp 325–337 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Sep 7, 2015

By E. C. Westman

Three-dimensional velocity tomograms were generated on a daily basis to image mining-induced changes to the overburden above a longwall mine. The hypothesis was that a coherent redistribution of seismic velocity, due to the development of high-stress zones, could be imaged at the mine scale. Seam depth was 360 m and source location depth varied from 100 to 1000 m. Sixteen geophones were distributed over a 600 by 600 m square area on the surface above the mine. More than 12,500 events were recorded over an 18 day period. The recorded seismicity provided input for the local-earthquake tomography code, SIMULPS. Eighteen tomograms were generated and high-velocity regions correlated well with high abutment stresses. Additionally, the high-velocity regions were observed to redistribute as the longwall face retreated. These results indicate that velocity tomography can be used to provide a better understanding of temporal changes within a rock mass, and can potentially be used to produce a better understanding of the mechanisms that lead to unanticipated ground failures.

Jan 1, 2008

By Matthew E. Fowler

The Central Subway will extend the recently completed 8.2-km long Third Street Light Rail line another 2.7 km north through the Union Square shopping district to Chinatown with a concourse-to-concourse connection to the Powell Street BART Station. One mined and two cut-and-cover subway stations are planned. Particular challenges include: tunneling under existing tunnels; variable ground conditions ranging from saturated alluvium to fractured bedrock; a congested urban setting and large-span caverns. This paper gives an overview of the project as it stands midway through the preliminary engineering stage along with a discussion of the rationale and design approaches that are being used to address the construction challenges of restoring light rail service in the most densely developed areas of San Francisco.

Jan 1, 2008

By Ernest E. Berger

"INTRODUCTIONOne of the outstanding problems in the normetallic industries, and one which involves two of the greatest of these industries, cement and gypsum, is the reaction of Portland cement with calcium sulphate. To all Portland cement clinker there is added in the manufacturing process, a small amount of retarder, as a necessary ingredient of the finished product. This retards the initial set, increases the strength, and adds to the plasticity of the cement so it will have the desired working and setting qualities. The retarder commonly used is gypsum, (CaSOA.2HO), which is the hydrous form calcium sulphate. Calcium sulphate is also available as plaster of Paris (CaSO4 1/2 HC) and anhydrite (CaSO4). The purpose of this inquiry was to determine the form or mixture of forms best adapted for retarder. The problem is complicated by the fact that cement clinker is a complex mixture of calcium silicates and aluminates, and that clinker from different mills, making cement of approximately equal quality, differs considerably in chemical constitution. Thus the same retarder may give very different results with different types of clinker, especially in the percentage of retarder required for the same degree of retardation.It has been known for some time that a small percentage of plaster of Paris will greatly retard the time of set of Portland cement as well as increase its strength and plasticity, but whether gypsum and anhydrite will have a similar effect is as such disputed question. The offects of gypsum have received little consideration in laboratory research because, even though it will not retard a clinker when the two are mixed in the laboratory, as has been noted in some instances, the cement will have a normal set when the two arc mixed in the large tube mill at the plant, so that practically, gypsum seems to be equally as goou as plaster of Paris, and because of the great saving in cost it has been used almost exclusively."

Sep 1, 1925

By David J. Hoadley

This report describes the development and underground operation of a semi-automatic, raise climber, Man and Supply Hoist System designed for stope access in underground metal and nonmetal mines. Demonstrated capabilities of the system include a 4000-lb payload capacity, control from the traveling cage and from up to five remote stations, operating in vertical or inclined raises 5 ft in diameter and up to 300 ft in length and a travel speed of 50 ft/min. The 'system has the capability of operating in crooked raises because the conveyance climbs two stationary wire ropes suspended down the raise. The drive unit is electrically powered with power and control signals supplied to the drive unit through an armored cable also suspended down the raise. The system has been designed for portability, ease of installation and minimum raise development. The system can be installed by two men in five shifts. The hoist has been demonstrated successfully in two underground applications. The first demonstration was in a 5-ft diam, 60 deg inclined raise over a 2-month period. The second demonstration utilized a vertical 5-ft diam borehole to access a blast-hole stoping area. The system successfully provided two shift-a-day service over a 7-month duration demonstration. This report provides a detailed description of the hoist design and its demonstrated performance in two mine applications.

Jan 1, 1981

By Jinhui Li

Silver is a very important metal used in a wide range of applications. It is necessary to recovery of Ag from electronic wastes for increasing of Ag price and circumstance protection. For separating and recycling Ag from Ag-Cu composite materials, thermodynamic data of reaction is calculated and some experiments have been proceeded with Ag-Cu composite material scraps, time, temperature, nitric-sulfuric mixed acid volume ratio and the volume ration of mixed acid vs. water have been discussed. The results show that the optimization conditions is that nitric-sulfuric mixed acid volume ratio 5:95, volume ratio of mixed acid vs. water 10:1, temperature 55?, time 25min. In the conditions, Ag can be selectively leached from Cu-based composite material, Cu base is not eroded nearly.

Jan 1, 2009

By J E. Nethery

At the Red Dome and Mungana deposits in north Queensland, Australia, it is proposed that mineralisation and alteration developed as a 'telescoped' overprinting continuum, ranging in style from hypothermal to epithermal, reflecting the major changes that developed in the regional setting over the period circa 325 - 290 Ma. Regional assessment suggests that this also applies to many other precious and base metal deposits within a 40 km length of the host Siluro-Devonian Chillagoe Formation.   A ten stage paragenetic sequence of structural preparation, multi phase intrusion and associated mineralisation, alteration and brecciation is postulated for the Chillagoe district.

Jan 1, 1995

By T. J. Batchler

Deformable materials are sometimes added to ventilation stopping constructions to prevent damage caused by convergence in coal mines. However, adding deformable materials can significantly reduce the capacity of a stopping to resist transverse loading. As part of its mining health and safety program, the National Institute for Occupational Safety and Health (NIOSH) has conducted research on the effect of various materials with different deformation properties on the transverse loading capability of a stopping wall. Based on a three-point hinge method of failure, a half-wall method of testing in the NIOSH Mine Roof Simulator was used to simulate full-scale wall behavior. This simulated the fracture initiation and eventual failure of the stoppings from transverse loading. The impact of the modulus of elasticity of various deformable materials was examined in this study. A polystyrene foam block with a low modulus of elasticity, which is commonly used as a deformable material, was shown to degrade the transverse load capacity of the stopping by as much 95%. Other materials with higher modulus of elasticity preserved more of the transverse load capacity of the stopping, but were not able to absorb as much convergence. This paper presents the results of a parametric study that quantifies the impact of various deformable materials in block stopping construction under transverse load conditions. Disclaimer: The findings and conclusions in this report have not been formally disseminated by the National Institute for Occupational Safety and Health and should not be construed to represent any agency determination or policy.

Jan 1, 2009

By B. E. Ydstie, B. F. Lund, K. R. Løvåsen, B. A. Foss

The paper presents sensitivity analysis for a dynamic model of submerged arc silicon furnaces. The model we study, called ?Simod?, was developed by Elkem in cooperation with NTNU and Sintef. It is today a much used tool in Elkem for operator training and analysis of the dynamic behaviour of the silicon production process. The aim of our work is to bring the simulator tool closer to industrial practice, and construct a mechanism to adapt the model to the behaviour of a running process, online. The paper presents the results of the sensitivity analysis that has been undertaken for important parameters in the Simod model. The parameters associated with the process inputs are electric power loss, loss of fixed C and reactivity of carbon. The output signals that have been investigated are fed quartz, tapped silicon and silica. The paper also interprets the results of the sensitivity analysis in a process operation context.

Jan 1, 2004

By Werner Burger

The Hallandsås project with a long history, first started in 1991, is well known in the tunneling community. In the past it has been stopped twice for technical and environmental reasons. The third attempt started in 2004 using a dual mode rock TBM. The heterogeneous highly fractured and abrasive rock mass as well as large areas of water bearing zones present most difficult subsurface conditions. The tunneling concept is based on the use of watertight segmental lining and a TBM able to operate in open mode, possibilities for extensive pre excavation grouting and high pressure closed mode operation up to 13 bar to cover exceptional conditions.

By Arnold Hammons

Automated temporary roof support (ATRS) systems have been incorporated into roof bolters since the 1970?s. During roof bolting, many injuries have occurred from large pieces of draw rock falling inby the ATRS beam and tipping back into the operator?s area. Other injuries have occurred due to smaller, sharp rocks falling onto the operator?s hand and arm during initiation of roof bolt drilling. These injuries are attributed to weak immediate roof, sometimes called roof skin failure. Even though ATRS systems support the roof and provide a measure of protection against roof skin failure, additional hazards sometimes do exist immediately inby and outby the supported roof. Design innovations such as the ATRS mounted rocker pad deflector systems have been designed to improve the roof bolter operator safety. This paper will inform the reader of the hazards, machine evolution through different design solutions, and the current state of the art in preventing roof skin failure injuries when roof bolting.

Jan 1, 2009

By D N. B Skinner, R L. Brathwaite, M S. Rattenbury

The Institute of Geological and Nuclear Sciences is undertaking a mineral resource assessment study of the Coromandel region, due for completion in July 2000. A key part of the study is the assembly of a geographic information system (GIS), a computerised tool for layering, analysing and presenting spatial information. The GIS is being assembled with ArcInfo/ArcView software and to date includes layers for a digital terrain model, an aeromagnetic map (open file mining company data), a geological map (from the QMAP project), areas of hydrothermal alteration, locations of mineral deposits (GERM database), stream sediment geochemical analyses (REGCHEM database), and a lineament map derived from satellite remote sensing data.

Jan 1, 1999

By Mathew Janes

"Sheet piles remain an economic solution to many shoring problems. However, installation of sheet piling suffers high noise and vibration with conventional impact or vibratory methods or low production and high expense with push techniques. Many projects simply will not allow sheet piling due to vibration concerns.Installing sheet piles with a tunable, high frequency Resonant vibrator provides high production with imperceptible ground vibrations. Recent projects in Canada have proven the technique on production projects where vibration sensitive structures are present immediately adjacent to the sheet piling. A project in Whitehorse, Yukon required a Waterloo style impervious sheet pile barrier be driven immediately adjacent to a sensitive, large diameter sewer line. The 1800 m2 Waterloo barrier was driven to prevent hydrocarbon leachate from entering the Yukon River. Proposed driving of the sheet raised concerned as the sewer serviced downtown Whitehorse. Monitoring of the sewer during Resonant driving proved the ground vibrations to be imperceptible. Use of the Resonant Driver prevented all concern over ground borne vibration of the sewer and allowed the contractor to progress at conventional, high production while maintaining low cost to the owner.Subsequent projects continue to prove that Resonant driving of sheet piles achieves high production while eliminating ground vibration.IntroductionA complex environmental clean-up problem required a unique solution. A historic oil and fuel transfer station in Whitehorse, Yukon is located on the Yukon River. The facility has been in use since the Second World War and witnessed much careless activity. The sand and gravel site provided ease of transmission of hydrocarbon leachates directly into the Yukon River. Continued use of the site required a barrier wall be constructed to prevent hydrocarbon from leaching into the Yukon River. A short construction season and restrictive fisheries window made for a compressed schedule. Along the shoreline of the property and within the required clean up zone a large diameter sanitary sewer collector line was present that serviced the majority of downtown Whitehorse. The design called for a barrier wall to be constructed along the waterfront adjacent to the sewer with cofferdams constructed out into the Yukon River to recover contaminated riverbed soils. The coarse sands and gravels meant high hydraulic conductivity into any kind of excavation, including slurried or drilled shafts that may have been used to construct a low vibration shoring system. Conventional hammer or vibrator technology would result in high ground vibrations that risked damaging the sewer. The Resonant Driver method was selected for its ability to drive sheet piles with high production and zero ground borne vibrations."

Jan 1, 2014

By R. K. Jade

Although several studies in combining and bifurcating flows in two-way junctions and splits are reported, deviations persist in the estimated shock loss coefficients (SLCs). Due to their complex nature, more work has to be done to be able to correctly predict flow losses at these locations. In two-way splits, the flow at bifurcation is known to be characterized mainly by two recirculating zones in the downstream branches, whereas, in a junction one recirculating zone is observed immediately downstream of the main branch. The relative flow rate in the branches (quantity ratios) is treated as the only parameter defining the losses at these locations. However, the effect of wall roughness, if any, on SLCs becomes important for mine ventilation. This paper presents the critical determinants of shock losses at splits and junctions at varying quantity ratios. The flow at 90º split and junction was examined both experimentally and numerically for Reynolds number in the range of 1.0×104 to 1.6×105. With a well designed laboratory setup, using precision instruments, velocity and pressure measurements were carried out, by using two scales of wall roughness. 3D numerical simulations for these experiments were conducted by using ANSYS CFX modeling tool. CFD simulations yielded results that are reasonably close to experiments, providing high degree of satisfaction in numerically predicting losses across the splits and junctions. However, comparisons of these numerical simulation results with existing literature standards showed significant under-estimation of shock losses by the standard literature by as much as 50%. A clear rise in the magnitude of shock losses was noted in both the approaches, with increased wall roughness. Based on the current studies, predictor equations incorporating quantity ratios are developed for accurate estimation of shock losses. Further investigations on roughness are needed, before one is able to incorporate wall roughness into the prediction of SLC.

Jan 1, 2009

By Adam K. Smith

Occupational hearing loss is a permanent illness with no recovery currently possible. For underground coal mine workers, Noise Induced Hearing Loss (NIHL) continues to be a serious health issue. One of the principal and fundamental machines used in underground mining operations is also one of the loudest. Noise generated on the continuous mining machine is the result of 3 operational components: the cutting system, the dust collection system, and the onboard conveying system. During underground acoustic evaluations, the conveyor system noise was observed to be dominant. In order to more closely examine sound generated by the continuous mining machine, sound power levels were measured in a reverberation chamber at the Pittsburgh Research Laboratory (PRL). Different chain types and configurations were installed on the conveyor system, and the resulting sound power level ranged from 118 dB(A) to 108 dB(A). Noise generated by the dust collection system was also examined and found to be 107 dB(A).

Jan 1, 2008

By Richard N. Spencer

"El surgimiento de los laboratorios combinados del Banco Minero del Perú en la industria minera facilitó las investigaciones y tratamientos en la composición de los minerales. Por tal motivo, el objeto del presente texto es remarcar la función del laboratorio químico del Banco Minero del Perú, en tanto le suministre información analítica y compleja sobre el campo mineral inorgánico, asi como garantice los resultados analíticos uniformes con la más alta calidad. Asimismo la disposición de dicha entidad química, abarca las compras del Banco Minero, plantas de beneficio del Banco Minero y el control químico requerido por las nuevas unidades de los laboratorios Metalúrgico y Petrográfico que son parte integrante de este Laboratorio Central. En este punto,el laboratorio petrográfico, como fuente permanente de información básica ayuda al geólogo o metalurgista y planifica mejor la función del laboratorio central, mientras que el metalúrgico, desarrolla pruebas de molienda de minerales, flotación mecánica y no mecánica, y pruebas de concentración por gravedad. Posteriormente están las secciones de recepción, trituración y muestreo del laboratorio, las cuales se componen del departamento de trituración, departamento de muestreo y departamento de archivo, respectivamente. Finalmente, este equipo de laboratorio, cuenta con un laboratorio de Microscopia, de preparación de muestras para el examen microscópico yde ensayos especiales, que en conjunto permiten un mejor tratamiento y descripción sobre los minerales a investigar."

Jul 20, 1956

By Zhou Wenbin

In this paper the mechanical properties of high carbon equivalent cast iron for automobile brake discs were analyzed through thermal analysis curves. Experiment results show that the mechanical properties have a strong correlation with thermal analysis curves and an effective way to predict the mechanical properties of high carbon equivalent cast iron was proposed based on the features of thermal analysis curves.

Jan 1, 2010

Coal bursts are one of the least understood yet the most critical hazards in underground coal mines. The ground motions induced by seismic events can trigger unstable failure of coal and rock mass and degrade the surroundings of an excavation. Therefore, the characteristics of ground motions should be fully investigated for an improved burst risk management. This paper analyzes ground motion features of a longwall panel from a typical underground burst-prone coal mine in China. The results showed that most of the ground motions on roadways were hardly initiate coal bursts due to insignificant energy input to the damage. The intensity of ground motions in near-field zone were nearly 20 times higher than those in far-field zone. The strongest vibration on roadway was induced by a coal burst with energy of 28,600 kJ, which can cause ground motion of 0.77 m/s and equivalent dynamic stress of 14.69 MPa. The findings of this paper can improve the assessment of seismic risks and its management.

Jan 7, 2020