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By S. Okubo, K. Fukui

Empirical equations established for estimating the rock strength of the working face based on the cutting forces of a tunnel boring machines (TBM) are further examined and discussed with respect to the dominant factors affecting TBM performance. Constants in the equations are related to TBM-specific parameters such as excavation (tunnel) diameter, cutter diameter, and cutter distance. The relationship between the constants and the TBM specifications is examined in this study on the basis of data collected at ten tunnels, and it is found that the constants are most strongly influenced by the cutter diameter and tunnel diameter. Zur Schätzung der Gesteinsfestigkeit an der Arbeitsfläche ermittelte empirische Gleichungen, die auf den Schneidekräften von Tunnelbohrmaschinen (TBM) beruhen, wurden weiter im Hinblick auf die vorherrschenden, die Leistung der TBM beeinflussenden Faktoren hin untersucht und diskutiert. In der Gleichung enthaltene Konstanten werden zu den TBM-spezifischen Parametern wie Auschachtungs- (Tunnel) Durchmesser, Schneidendurchmesser und Schachtlänge in Beziehung gesetzt. Die Beziehung zwischen diesen Konstanten und den technischen Daten der TBM wird in dieser Studie auf der Basis der bei 10 Tunnelbauten gesammelten Daten untersucht. Dabei wurde gefunden, dass diese Konstanten am stärksten von den Durchmessern der Schneiden und der Tunnel beeinflusst werden. Cette étude examine et discute les équations empiriques permettant d'estimer la résistance de la roche attaquée aux forces de coupe des tunneliers dans le cadre de l'étude des facteurs dominants affectant les performances des tunneliers. Les constantes de ces équations concernent les paramètres spécifiques des tunneliers comme le diamètre d'excavation (du tunnel), le diamètre du couteau et la distance de coupe. Cette étude examine le rapport entre ces constantes et les caractéristiques techniques des tunneliers d'après des données collectées dans dix tunnels et elle conclut que ces constantes sont principalement influencées par le diamètre du couteau et le diamètre du tunnel.

Jan 1, 2003

By B Vorster

Falls of Ground is one of the highest causes of incidents, accidents and fatal injuries in our mines today. These falls of ground may occur as soon as the face is exposed after blasting or after machine cutting. The falls of ground can also occur after support has been installed. There are many reasons why these falls occur before and after supporting of the face. It is therefore important to support the exposed face as soon as possible to prevent the falls of ground. It is also very important to support the face with the correct support products and to support the face as designed and required by the mining engineers. The possible reasons for falls of ground, possible support methods and the products available will be discussed in this presentation. In typical conventional narrow vein stoping operations, the use of conventional temporary support components to offer some support to workers, whilst the permanent and generally more elaborate support system gets installed or constructed, still results in injuries to people. The author wishes to discuss the following items in this paper:- ? Introduction ? Basic face behaviour after exposure ? Controllable Parameters ? Mining Engineers support designs ? Primary and Secondary Support ? Products available for prevention of falls of ground

Jan 1, 2008

By K Thorpe

Amorphous silica deposits have been identified at Tikitere and Taheke near Rotorua. Two areas at Tikitere have been surface sampled and drilled to establish a resource of amorphous silica in excess of one million tonnes. A pilot plant was established to develop a process to manufacture a high quality super pozzolanic material. This development process took two years before a commercial product was introduced to the construction industry in 1996. The amorphous silica product, marketed as Microsilica 600, is used as a pozzolanic material to produce high quality strong and durable concrete, sprayed tunnel linings, mortars and grouts. Microsilica 600 has been used locally and exported to 11 countries.

Jan 1, 1999

By M. Wong-Kian, L. A. Cornish, A. van Bennekom

Samples of four different satellite materials were prepared by either hot isostatic pressing (HIP) of the powder or tungsten inert-gas welding of rod onto a 316 L stainless-steel substrate. The samples were subjected to a series of comparative erosion corrosion tests, and generally the Hipped samples experienced between 13 and 24 per cent less loss in mass than the equivalent welded alloys. Resistance to erosion corrosion increased with increasing carbon, chromium, and tungsten contents. Metallographic studies indicated the differences in carbide content between the different satellite materials, and the differences in morphology between the Hipped and welded samples. Finer and more homogeneous microstructures were

Jan 1, 1995

By Elaine T. Cullen

Miners, like many skilled blue-collar workers, are not traditional learners. They have not generally been successful in classroom-type settings, preferring to learn on the job in a hands-on environment. U.S. miners are required to have annual safety training, but they rarely view this positively. In fact, it has been called “safety jail” by many of them, who regard it as a time to get a little extra sleep. The challenge then, was to find a way to develop effective safety training for these people, particularly in view of the fact that their work is among the most dangerous of all occupations. Miners are born story tellers. They share “near-miss” stories, stories about master miners they have known, and stories about how things used to be. These stories not only pass along information about what will happen if a miner fails to respect the mining environ-ment, they also instruct listeners in the culture of mining and the values it embraces. Stories, it seems, are a way to get safety messages to miners, especially inexperienced ones, and using older, wiser miners in these stories is an obvious choice. This paper will discuss how the training videos created to get safety messages to miners were developed, how “master miners” and story lines were chosen, and how the resulting videos have been received in the mining industry.

By G. Wren

As base metal sulphide resources become increasingly challenging to process, producers seek alternative options to treat concentrates. This study considers the mineral, elemental, and leaching character of a West Australian nickel sulphide deposit (Cosmos Nickel Project). After a brief review of the published work bench top leach tests were conducted to examine the factors which impact the kinetics of nickel sulphide leaching such as particle size, temperature, acid strength and type, concentration of copper sulphate and sodium chloride, and oxygen partial pressure. The effect of sodium chloride was considered due to the common occurrence of hyper saline water at West Australian nickel sulphide mine sites. Ultrafine grinding to an 80% passing size of 10 µm resulted in high nickel leaching efficiency. Moreover, higher concentrations of acid, copper(II) and sodium chloride also gave higher nickel and cobalt leaching efficiencies but arsenic precipitated as FeAsO4. Under the most suitable conditions the extractions of nickel, cobalt and arsenic at 90oC after 6 hours were >95%, 90% and <5%, respectively. The comparison with results from high pressure operations indicates the possibility of using a hydrometallurgical flowsheet based on fine grinding and atmospheric pressure leaching and warrants further investigations.

Jan 1, 2014

By R. V. Ramani

This volume, the first of a six volume final report, provides an executive summary of the research and results carried out under a grant from the U. S. Bureau of Mines on underground coal mine ventilation. Under the project, a mine ventilation simulator was developed. Sensitivity of leakage and friction factors on the total quantity and pressure requirements was studied. The simulator was applied to a new mine under development, and to an operating mine, to demonstrate the usefulness of the simulator in ventilation planning and in evaluating proposed changes to existing ventilation system. The titles of the other volumes are as follows: Volume II: Mine Ventilation Network Theory Volume III: User&apos;s Manual for PSU/MVS Volume IV: Sensitivity of Leakage and Friction Factors Volume V: Application of PSU/MVS to Ventilation Planning of a New Mine Volume VI: Application of PSU/MVS to the Analysis of Modifications to Existing Ventilation Systems

Jan 1, 1977

By R. Graeme, J. Komadina

Gold Fields acquired an option to purchase the Cerro Corona Project, located in Hualgayoc, Cajamarca Department, Perú, in December 2003. In January 2006, the option was taken up and the transaction closed. During the intervening months, Project development occurred against the backdrop of a Presidential election, increasing national social activism and environmental regulation, rapidly escalating operating and capital costs, as well as unprecedented demand for engineering and technical skills. Project “Lessons Learned” are outlined and discussed in the context of an evolving strategy.

Jan 1, 2007

By M O. Tade, M W. Sze

The particle dynamics of a mixture of coal and zircon system wasstudied in a scaled-down cold model of an industrial kiln. Thefactors investigated in the study were rotational speed (N),zircon-to-coal feed ratio (B), coal particle size (dpc) and the angle of inclination (*) of the kiln. The technique used is the residence time distribution (RTD) method. It was found that rotational speed and angle of inclination are important parameters that affect the residence time of particles in the kiln. A mathematical model for predicting the mean residence time of particles in the rotary kiln was developed. Comparisons with reported models for such systems are discussed.

Jan 1, 1998

By F. C. Wagner, E. P. Klier, D. E. Nulk

The presence or absence of plastic strain at a cleavarage surface is a question of much importance, and upon its answer depends future possible theoretical work. To investigate this question back-reflectinn X ray patterns were obained on the cleavage facets of ferrite grains. The test set-up consisting of FeK colli- mated radiation, single grain material and stationary cassette and specimen will not lead to a diffraction pattern, in general, but is an ideal arrangement for the exami-nation of surface effects. A pattern taken on hydrogen purified

Jan 1, 1949

West Virginia ranks second in the nation in coal production, surpassed only by Wyoming, and usually accounts for 15 to 20percent of the nation&apos;s total annual production. Cod occurs in seams of minable thickness in all but nine of the state&apos;s 55 counties. There are two coal- producing regions, the northern field and the southern field. West Virginia coal is mined by both underground and surface methods. Underground mines in West Virginia account for a major portion of its coal production. Surface mines are generally contour operations and, especially in the southern field, are in steep slope areas, with slopes greater than 20 degrees. Many of the surface mines remove multiple seams. Recoverable reserves in West Virginia total in excess of 55 billion tons of bituminous coal. West Virginia&apos;s regulatory program was conditionally approved on January 19, 198 1. Its Abandoned Mine Land Program was approved February 23,198 1, with emergency authority granted on August 26,1988.

Jan 1, 1992

By Daniel W. Su

This paper presents the results of a detailed geotechnical study on the potential multiple seam interaction between the No. 2 Gas (upper) and the Powellton seams, which are separated by an average interburden of 45 ft. The interburden consists of 4 ft of clay shale below the No. 2 Gas seam, 38 ft of massive sandstone, and 3 ft of shale above the Powellton seam. The No. 2 Gas seam was mined about 60 years ago, and many water-pooled areas were projected to be present. The deepest overburden over the No. 2 Gas seam is about 750 ft. To evaluate the potential interaction between the two mine works and to determine the pillar safety factor, Analysis of Multiple Seam Stability (AMSS) software was initially used to determine pillar dimensions to obtain a minimum safety factor of 2.0 for areas under pooled water, as well as a minimum safety factor of 1.5 for areas not under pooled water. Furthermore, to assess the quality of the interburden rock strata, two surface core holes were drilled, and rock cores were tested in the laboratory for their strength and elastic moduli. Using the experimentally determined strengths and moduli as part of the input parameters, the RocScience Phase2 finite element program was employed to model the stress field scenarios and estimate the safety factors of the interburden rock strata before and after Powellton seam mining. The pillar safety factors derived from the Phase2 analysis were in excellent agreement with those obtained from the AMSS analysis. Phase2 results also predicted that the effect of the Powellton seam mining, first mining only, would reach a maximum of 19 ft above the Powellton seam, which led to the proposal of drilling 25-ft deep test holes to detect water, instead of the 45-ft deep test holes mandated by MSHA. The proposed test-hole height was accepted by both Mine Safety and Health Administration (MSHA) District 4 and the state of West Virginia. Mining of the Powellton coal seam commenced in February 2011 and continued for eight months. To date, no 25-ft deep hole has encountered water under the water-pooled zone, which validates the RocScience Phase2 finite element analysis. Also, inmine observation of excellent pillar stability and roof condition confirms the validity of the AMSS analysis.

Jan 1, 2012

By Andrey V. Tarasov

To carry out a physicochemical substantiation of a transition to ?soft? modes of reduction of calcine obtained by desulfurizing roasting of nickel concentrate produced as a result of copper-nickel converter matte separation in a nickel anode production circuit, an analysis has been conducted of the macrokinetic behavior of actual calcine samples in the presence of gaseous H2-CO mixtures and solid reductant additives. Within a temperature range of 900°C to 1100°C the main regularities typical of the calcine reduction process with individual gases (H2, CO) also take place when using a gaseous mixture. Under the conditions of low-temperature (900°C to 1000°C) nickel oxide reduction with products of fuel oil conversion in the presence of coke, the role of the latter is insignificant from the technological viewpoint. As a result of the present investigations, we have obtained analytical expressions of macrokinetic parameters of the reaction interaction within the [NiO] calcine-H2-CO-C-CO2-H2O-O2-N2 system.

Jan 1, 2005

By Francisco Camus

El proceso de exploración en las campañas mineras es la primera fase del negocio y constituye una de los principales herramientas para su supervivencia, desarrollo y valorización de la industria. En este sentido, el presente texto señala la experiencia de Codelco en la exploración en Chile y su aplicación en Perú. Así, el conocimiento obtenido por Codelco realizado en el norte y centro de Chile, ha generado la formulación de modelos de exploración predictiva durantes los últimos diez años. Dichos modelos incorporaron el conocimiento logrado en el nivel de cada yacimiento individual, los entornos distritales y las franjas metalogénicas donde estos ocurren. En consecuencia, esta experiencia obtenida por Codelco y el reconocimiento de la continuidad en Chile, se extiende en el Perú y se presenta como una oportunidad de interés para el desarrollo de programas de exploración a futuro.

Sep 13, 2001

Newmont Waihi Operations is participating in the initiation of a community liaison forum in association with the local district council. The objective is to provide a forum for the free and regular exchange of ideas, concerns and information, and through improved communication seek to achieve a more comprehensive set of solutions to community, operating and closure issues associated with Martha Mine. A similar liaison forum has been operated on two previous occasions during earlier phases of the present mine&apos;s operation. This paper deals with the practical aspects of setting up a liaison forum to act as an effective conduit between regulators, mine operators, local businesses and the community. The mechanisms and procedures for identifying community issues and concerns are dealt with. The actions and structures required to ensure effective ongoing community &apos;buy in&apos; at all levels are discussed. Corporate philosophies are addressed. Specific examples from Martha Mine, Waihi New Zealand will be used to illustrate the paper. This will include a brief explanation of previous and current community issues, Newmont Waihi&apos;s operations both at Martha Mine and the proposed Favona underground mine, and the practical issues involved in setting up a liaison forum.

Jan 1, 2003

By A. Arik

An accurate estimation of mining block grades continues to be a challenging task for ore reserve practitioners. Two of the factors that affect the accuracy of the estimates are the estimation method used and the variability of the mineralization in the deposit. The objectives of the study are twofold: Firstly, to see how different estimation methods perform on a given deposit. Secondly, to determine the impact of particular nature of the mineralization on the results. The comparison of several estimation methods for the prediction accuracy is performed using the conditional simulation results as the basis.

Jan 1, 2000

By Jueun Lee, Jong-Hwa Yoon, K. Rider, Bernard J. Martin

Whole body vibration is known to affect movement accuracy [1], however little is known about changes in the organization of movement and movement strategies used to limit the influences of perturbations. The specific aim of this work is to analyze the motion and coordination of upper body segments of seated operators performing reaching tasks under whole-body sinusoidal vibration exposure and simulated vehicle ride motion. The long-term objective is to model reach coordination and predict the dynamic behavior of the upper body motion under vehicle vibration exposure. Method The reach task consisted of pointing with the right hand index finger to targets located on touch screens placed in front of the subject, 45° overhead and 90° to the right in the mockup cabin of an HMMWV placed on a 6 DOF ride motion simulator. The task was performed under stable (no vibration) and vibration (sinusoidal vibration or simulated ride motion) conditions. A motion capture system was used to record kinematic data of reflective markers to recreate body link trajectories. Joint angles (torso, shoulder and elbow; Figure 1) were then computed using quaternions. Coordination between body links was defined as a) the joints angle-versus-angle relationships between the upper arm and lower arm, and b) the joint motion onset relationships between torso, upper arm and lower arm in the time domain. Results Angle–versus-angle relationships. The relationship between upper arm vs. lower arm angle and torso vs. upper arm angle for a far forward reaching movement in the stable (solid lines) and vibration conditions (dotted lines) are illustrated in Figure 2. Fig 2A compares the control condition with a 4 Hz lateral vibration while Fig 2B compares the control condition with a 6 Hz vertical vibration. It appears that under vibration exposure the reduced upper arm extension is compensated by an increase in torso flexion. This effect is seen in the last phase of the movements (encircled areas). In addition, the lower arm extension is delayed under 6 Hz vertical vibration (Fig 2B left panel). Time of joint motion onset. The timing relationship between torso, upper arm and lower arm is largely a function of the target to be reached. Examples of delays between body links are illustrated in Figure 3. The control condition is compared to a 6 Hz vertical vibration for three

Jan 6, 2006

Blasthole deviation is a frequent, well documented and undesirable occurrence in mining operations. It is caused by the drill string mechanics, operating variables and the interaction between the drill bit and the rock mass characteristics. It is composed of three distinct components: collaring or marking error, alignment error and trajectory deviation. This study has focussed on the dependence of trajectory or natural deviation on the geological features of the rock mass being drilled.

Jan 1, 1996

Jan 1, 1967

By R. A. Reiley

Introduction Democratic countries are founded on the principle that all citizens have the right to participate in policy setting and decision-making processes. Citizen participation is especially evident in environmental issues and policies. In the United States, there are currently over 10,000 environmental organizations and new ones are being formed each year. Many of these organizations are formed on a watershed basis and are particularly concerned about the impact mining has on the environment. While the environmental issues vary from area to area, most concerns center around mining impacts related to subsidence, water pollution, and water diversion. Citizens have a number of avenues for participating in lawmaking that affects the mining industry. Some of these avenues include participation in litigation and citizen ballot initiatives. In addition, there are less formal methods of participation that include attending public meetings, commenting on agency rules or lobbying on specific legislation. The intent of this article is outline the various public participations mechanisms, highlight the latest legal developments that have affected mining industry through citizen participation, and briefly discuss emerging issues.

Jan 1, 2001