Search Documents

By L. Yan, C. Zhou, M. Reyes

"The MINER Act requires the installation of post-accident, two-way communications and electronic tracking systems for all coal mines. One communication system which can satisfy this requirement is an electrode-based, through-the-earth (TTE) communication system, which sends signal directly through the overburden of a mine. The performance of these types of systems relies on several controlling factors such as earth conductivity, overburden depth, operating frequency, TX/RX antenna length, TX/RX offset, TX/RX orientation angle and TX current. In an effort to estimate attenuation through the earth, NIOSH researchers developed an analytic solution for the electrical field distribution of an electrode-based TTE communication system for the extremely low-frequency (ELF) range (< 30 Hz) or DC excitation source. The analytic model was then validated using test data measured at an operating coal mine. The validated model can be used to optimize the operating frequency, estimate the required transmitting current, choose appropriate TX/RX orientation, and predict the performance of an electrode-based TTE system at a coal mine. INTRODUCTION One of the requirements of the Mine Improvement and New Emergency Response Act (MINER Act) of 2006 is the installation of post-accident, two-way communications and electronic tracking systems for all underground coal mines. As one of the through-the-earth (TTE) wireless communication methods available for the mining industry, the electrode-based, or linear, TTE systems establish communication by inducing a current within the earth medium by use of a pair of current probes. The resultant current is detected as a voltage by a similar set of distant probes. These probes could be an insulated piece of wire tied to two electrodes grounded at distant ends, or the grounded ends could be rails, roof bolts, or grounded electric rods. The analytical solution developed in a homogenous half-space, for this form for various transmitter/receiver (TX/RX) configurations, will be presented in this paper. The communication signals can be sent either from underground to surface (uplink) or from surface to underground (downlink). In order to achieve a successful communication link, it is necessary to understand the electric fields within the earth so that the appropriate size of transmitting antenna, TX/RX relative orientation, and operating frequency can be chosen. Hill and Wait gave the explicit forms of partial magnetic fields and partial electric fields of electrode-based TTE downlink communication with finite cable length [1]. In prior research, the E-fields of electric line transmitter were obtained for a static TX current [2] [3]. In this paper, the general and explicit forms for electrode-based TTE electric fields are developed and presented. The solutions for the extremely low-frequency (ELF) range (< 30 Hz) or DC excitation source obtained from these forms are presented. Also, factors that affect the E-field strength at RX are discussed."

Jan 1, 2017

By M. Shriwas, F. Calizaya

"Controlled recirculation may be considered as a beneficial means in mines of cold climate, where heating of air is required, and in deep or extensive mines, where cooling of air is required. Controlled recirculation can be designed by proper sizing of the booster fans with respect to main fan. Intuitively, it seems that the buildup of methane at the face will cease when a steady state condition is attained, and also that, at that same time, the maximum concentration at the face will remain same as in the return air. This supposition is proved by mathematical analysis that considers uniform mixing of methane in air in successive cycles of recirculation. This study includes two scenarios to show the effect of controlled recirculation on methane concentration in a sample network. Firstly, when recirculation crosscut exists near the working face; secondly, when recirculation crosscut exists away from the working face. The later scenario shows lesser buildup of methane concentration than the former one. INTRODUCTION The controlled recirculation is designed purposefully to allow a partial fraction of used air that increases the air velocity due to increased quantity of air and consequently allows effective dilution of contaminants to improve local ventilation condition at the working face. It can be designed by proper sizing of booster fan with respect to main fan in a ventilation network. Controlled recirculation may be categorized as crosscut, in-line or combined system based upon the configuration of the booster fan locations in a district ventilation network. Research on controlled recirculation has shown numerous benefits of controlled recirculation especially in deep or extensive underground mines, where further heating or cooling is required (Calizaya 1990; McPherson 1993 and Jones, 1987). However, fear of buildup of concentration has misled the mining communities to view the controlled recirculation as a hazard and deprived the mining industry to derive benefits from recirculation. Intuitively, it seems that the buildup of methane at the face will cease when a steady state condition is attained, and also that, at that same time, the maximum concentration at the face will remain same as in the return air. This supposition is proved by mathematical analysis that considers uniform mixing of methane in air in successive cycles of recirculation. This study includes two scenarios to show the effect of controlled recirculation on methane concentration in a sample network. Firstly, when recirculation crosscut exists near the working face; secondly, when recirculation crosscut exists away from the working face. The later scenario result shows the less buildup of methane concentration than former scenario result."

Jan 1, 2016

By Anne Kathrine Kalager

"Stretching from Norway’s capital, Oslo, to the city of Ski, a new railway line is under construction with a 20 km long hard rock tunnel. This is a major project with high demands regarding quality, cost and schedule. In addition, restrictions concerning locations close to sensitive urban infrastructure require execution with the highest level of precision and expertise. The new double track railway line forms an important part of the intercity rail development southwards from the capital and includes the longest railway tunnel to date in the Nordic countries. With its novel methods and solutions, this project offers a model for future railway project developments in the region. This paper provides general pertinent details and facts relating to this current railway project and includes a description of the project with information relating to concept and design of the tunnels, geological conditions, particular challenges, selected tunneling techniques and contracting strategies. THE FOLLO LINE PROJECT The Follo Line is a new 22 km long double track railway line under construction between Oslo Central Station and the city of Ski. The project is divided into four subprojects, as shown in figure 1. The main part of the project consists of a 20 km long hard-rock tunnel, which will be the longest railway tunnel in the Nordic countries to date.The Østfold Line is the existing double-track railway line running between Oslo Central Station and Ski serving 12 local stations. The new Follo Line will offer a direct service, without stops, between Oslo Central Station and Ski and reduce the travel time from 22 minutes to 11 minutes. After completion of the Follo Line, these two railway lines will, in combination, more than double the capacity for train transport in the region south-east of Oslo."

Jan 1, 2016

By Thomas A. Gray

The Dolph Mine fire site is located in Lackawanna County, PA, approximately three miles northeast of the city of Scranton. The fire was burning in both coal refuse (culm) and underground anthracite mine workings. It was reportedly begun by rubbish burning on top of a culm bank. A site investigation was completed in 2006 to define the extent of the fire and to recommend fire control measures. A cut off trench was selected as the principal control method. Plans and specifications were prepared in late 2006. The project was bid and a contractor selected in early 2007. The trench construction was completed in 2007. This paper describes the investigation and selection of the fire control method and discusses the trench construction.

Jan 1, 2009

By E. C. Roper

Landusky Mining, Inc. and Zortman Mining, Inc. are two registered Montana Corporations wholly owned by Pegasus Gold, Ltd. of Vancouver, B.C. The Zortman and Landusky Mines are located in the Little Rockies District of central Montana. The Zortman-Landusky mines produced 2,100 kg gold in 1982. A total of 3,250,000 t of ore per year are mined during the period March 1, to September 15, at an average grade of 1.04 gm/t (0.03 oz/t) gold and 13.4 gm/t (0.385 oz/t) silver at a cutoff grade of 0.35 grams of gold/ton (0.01 oz of Au/t) of ore. The stripping ratio during 1983 is anticipated to be 0.75/1 waste to ore. Combined average plant capacity of the two Merrill-Crowe plants is 9,840 lpm (2,600 gpm). The combined heap spray capacity of the two plants approaches 18,900 lpm (5,000 gpm). The mine employs approximately 200 people, about half of these work for the mining companies and the other half for the mining contractor, N. A. Degerstrom of Spokane, Washington. Net profit in 1982 for Zortman and Landusky Mining, Inc. approximated $4,900,000 at an average gold price of $11.40/gm.

Jan 1, 1983

By André Vervoort

At the 2017 ICGCM-conference in Morgantown, WV, a case study was presented with measurements of the upward surface movements or uplift after the closure of two neighboring coal mines (Winterslag and Zwartberg, Belgium). One was closed in the sixties, and the other closed in 1988. The study was based on satellite data (Radar-interferometry or InSAR). The analyses showed both a significant variation of uplift values above the mined area and the surrounding zones, and a variation of the uplift rate as a function of time. In other words, the phenomenon of uplift is complex. At that time, it also was clear that more research was needed to better understand this phenomenon, e.g., an identification of the various mechanisms that are relevant for the process of uplift and the quantification of the various impacts. A systematic analysis of all relevant parameters resulted in a framework that forms the basis for the analytical calculations of uplift values. These calculations show that the main impact is due to changes in the hydrostatic pressure. However, the expansion of the softest parts, i.e., the collapsed or goaf material, is not only important, but the expansion of the (stiffer) non-collapsed strata layers due to a change in pore pressure also must be integrated into the model. For the case study, the partial flooding of the underground after closure of the mine that was abandoned in the sixties is integrated into the model. Larger stiffness values also are applied for this mine, in comparison to the values of the more recently closed mine. Overall, a very good correlation is observed between the InSAR-measurements and the calculated values along a north-south transect.

By Nasib Al Habib, Hooman Askari-Nasab, EUGENE BEN-AWUAH

In-pit crushing and conveying (IPCC) is getting popular in deeper open pit mines as a suitable alternative to truck haulage because it offers a lower operating cost due to shorter haulage distance and less truck requirement. Semi-mobile in-pit crusher, currently the most popular IPCC system, is relocated every two to five years, and the short-term plan needs to be updated accordingly. To the best of our knowledge, short-term planning with IPCC is an area of research that has yet to be explored extensively, and hardly any model can generate a shortterm extraction sequence considering an IPCC. This research work proposes a mixed integer programming model to develop a short-term production plan within a time horizon of 12 months. The model's objective is to optimally allocate shovels to minimize the cost of material handling and maximize revenue subject to meeting plant requirements, maximum allowable tonnage variation and IPCC location constraints to achieve production and NPV targets set by the strategic plan. The proposed model will be implemented in an iron ore mine case study for verification. The model is developed and solved using MATLAB. The comparison of results between scenarios with and without IPCC justifies the use of IPCC in large open pit mines from a short-term perspective.

Jun 25, 2023

By Joshua Farmer, Mike Gianforte, Tao Jiang, William Gettings

The Two Rivers Water Reclamation Authority (TRWRA) in Monmouth County, New Jersey, is replacing its aging Pleasure Bay Interceptor (PBI) with a new 54-in interceptor in a 3,250-foot long 8 to 10-foot diameter tunnel and a new 50-mgd main pump station (MPS). A comprehensive phased geotechnical investigation was performed, including SPTs, CPTs and geophysics. A channel filled with soft marine sediments was identified. The tunnel is set in stiff to hard marine soil to enable using a less expensive open-face TBM. The thickness of tunnel cover under the channel is optimized through numerical analyses to avoid a deeper pump station yet maintaining tunnel stability with controlling seepage.

Jun 13, 2021

By Ademar Lopes, Victor Silva, Heitor Silva, Gustavo Usero, Roberto Rolo, Lucas Pereira, Gabriel Moreira, João Lague, Arthur Endlein, Matheus Feitosa

Grade control models are supposed to provide a higher resolution than long-term or interim models. However, available grids from diamond or reverse circulation drilling do not provide that required resolution. In this study, a geostatistical workflow is proposed to integrate available grade data from production blastholes with its operational parameters taken when drilling downhole. The step of geological logging can be replaced by machine learning models for classifying blastholes into lithologies and hardness classes. Next, indicator and ordinary kriging use the classified blastholes and previous data for estimating the model domains and the grades within each one. The workflow is applied in a world class iron ore mine in Brazil.

Jun 25, 2023

By Armando Z. Remacre

The purpose of this paper is to attest the effectiveness of conditional simulation technique&apos;s for determining the principal pre-mining control parameters during mine planning. These parameters include: determining the selective mining unit size, the optimum pre-mining grid spacing and the number of mining faces to be used. The research work was developed in an iron ore deposit located in the Minas Gerais State, Brazil. Phosphorus was considered the master control variable for the research work. This paper provides the structural analysis (variography) , a description of the steps the were taken for setting up the numerical model, the kriging studies which were applied to the numerical model and the final optimum grid spacing, block size and number of mining faces.

Jan 1, 1992

By C. Sampaio, C. Petter, M. Veras

"INTRODUCTION Use of sensor technology applied to the gravimetric beneficiation is intended for the selective preconcentration or separation of various minerals. Sensor Based Sorting (SBS) uses sensors to identify the particles and separate them by a mechanical process (flap) or pneumatic ejection valves (Wotruba et al. 2014). The principle of the SBS technology to separate mineral particles consists of three phases which cover feed,detection and separation. (killmann, 2009 Apud nienhaus et al. 2014). The applicability of the technique in an early stage of beneficiation enables free particles and poor grade to be a part of the process. The mass of tailings to be processed can be removed at the initial stage to save energy, water and equipment maintenance (Wotruba et al. 2014). Lindner (2010) suggested that the use of SBS technology would only will be possible if there exsists an electromagnetic interaction in all the wave spectra interacting with the solid ore. The interaction of electromagnetic waves depends directly on the characteristics of the material. The material receives a spectrum of electromagnetic waves by irradiation and this results in a reduced wavelength with differing types radiation such as fluorescence, reflection, remission, absorption, transmission and transmission. The frequency of the wave spectrum varies between 1000 and 1020Hz, illustrated by the data in Figure 1, which shows that each type of sensor emits a wavelength inversely proportional to the frequency ranging from 10-11pm to 104km, and the frequency that varies between EHz 103 and 1020kHz. The difference between the electromagnetic spectrum variations can only be visible to the human eye at wavelengths with intervals between 380nm and 780nm (Wotruba et al. 2014). One of the main advantages of operating with imaging sensors is the versatility of the images which can take on zero, one, two or three dimensions shown below as a point, a line, an area or a spatial image, as illustrated in Figure 2. According to Schubert (1988), to separate a mineral particle it is necessary to follow the characteristics of mineralogy, physics and chemistry with or without use of water. The use of new technologies can help reduce operating costs and improve utilization of mineral resources."

Jan 1, 2016

By V. R. Degner

Given: the process tonnage, performance objectives, and plant floor area, the paper will outline the metallurgical and machine hydrodynamic scale-up procedures for translating the lab flotation test results to the design of a full size flotation machine installation, including the machine number, size, and arrangement. Machine selection considerations for rougher, scavenger and cleaner duty, and special considerations relative to specific applications, will be summarized where appropriate. The value of kinetic modeling in quantitative metallurgical (lab to full size machine) scale-up will be reviewed considering a coal installation, and design information for additional applications such as copper, molybdenum, iron, phosphate, and potash will be discussed.

Jan 1, 1986

By Donald J. Worth

When Eugene Bailey asked me to contribute to this session on "Canadian exploration - 1976", it took a little coaxing before he got me to agree. My immediate reaction was, what could i say about Canadian exploration that already had not been said a hundred times in the past few years; secondly, why include a banking person in such a discussion? Everyone knows banks only come into the picture after the discovery has been made and feasibility well established and validated. Rather than wrestle with these misgivings, I decided to take the easy way out and go on blind faith in Eugene - that is, he asked me so he must think that I could come up with some useful thoughts and at least touch upon some of the pros and cons of exploration in Canada. The object of the whole exploration exercise is to Find economic deposits, once they are found, one cannot really move them elsewhere to mine them. It follows, therefore, that we should really be speaking about the pros and cons of mining In Canada and my treatise will eventually lean in this direction. In any event and before getting down to the pros and cons, let us take a quick look at the history of mineral resource development in our country since the end of world war II. At that time, we were producing well under one billion dollars worth of mineral products including hydrocarbons.

Jan 1, 1976

By Jean-Marie Deschamps

In an approach to the complicated study of bauxite from Les Baux de Provence it is necessary to consider the paleogeographical context of all the bauxites in southern France. These bauxites are of Karstic type, belonging to a metallogenic area extending from the Pyrenees Mountains to the Alpine Massif. Within this area each deposit does not always correspond to the same geological period. There are differing opinions regarding the origin of Karstic-type bauxite and a discussion of these various theories is beyond the scope of this paper. Bauxite of Les Baux, in Provence, was discovered in 1821 by the chemist, Berthier, near this picturesque village located in the region of Arles. It is Les Baux from which the name of bauxite originates. For a long time this bauxite was of no interest because of high silica &apos;and mediocre alumina content. Besides, the calcium carbonate content is somewhat high and is one of the main characteristics of Les Baux bauxite. The problem of exploration of the Les Baux deposit has been to prospect minable zones according to traditional norms where silica and carbonate are low.

Jan 1, 1977

By Erik S. Bernard

"INTRODUCTION Conventional steel bar reinforcement is used in many tunnel linings to provide high flexural and tensile load resistance. These Reinforced Concrete (RC) tunnel linings may suffer flexural cracking during service or, in the case of precast concrete segments, during production, handling, or installation. Cracks can lead to corrosion of steel reinforcement, so limits are placed on maximum acceptable crack widths to reduce the likelihood of corrosion during the intended design life (AFTES, 2013; MC2010, 2012). However, the relatively light level of reinforcement used in many applications can result in quite wide in-service crack widths, so either additional steel bar reinforcement is required to limit maximum crack widths, or fibers can be included to control crack widths. Numerous investigations have been undertaken into the efficacy of including steel fibers to reduce crack widths in conventionally reinforced members (Stang and Aarre, 1992; Abrishami and Mitchell, 1997; Bischoff, 2003; Dupont and Vandevalle, 2003; and Jansson et al, 2010), but steel fibers suffer the problem that they are at least as sensitive to corrosion at cracks as steel bars and therefore have similarly tight limits placed on acceptable crack widths (AFTES, 2013). An alternative means of maintaining narrow crack limits in RC members has therefore been sought. The current investigation was instigated following an observation that theories promoted as an explanation for the ability of steel fibers to reduce crack widths in reinforced concrete flexural members (Deluce et al, 2014) do not depend on the material composition of the fibers used but instead depend primarily on the tensile stress generated by the fibers across cracks. Since it is known that macro-synthetic fibers are capable of equaling the post-crack tensile capacity of steel fibers, it has been hypothesized that macro-synthetic fibers are also capable of reducing crack widths in reinforced concrete flexural members but with the added advantage that macro-synthetic fibers are completely immune to the effects of corrosion. Use of macro-synthetic fibers to reduce maximum crack widths in reinforced concrete flexural members subject to aggressive environmental exposure is more rational than use of steel fibers because steel fibers are very sensitive to the corrosive effects of environmental exposure at cracks. The current investigation was therefore undertaken to explore the potential use of macro-synthetic fibers to reduce maximum crack widths in reinforced concrete members subject to flexure. Barchip BC54 fibers were selected as they are one of the most widely used and competitive high performance macro-synthetic fibers currently available."

Jan 1, 2016

By L. R. Moore

The World Health Organization (WHO) considers contamination from oxyanions, such as selenium and arsenic, a global concern. While their elemental forms are toxic, the aqueous oxyanions are more so. These aqueous forms, which exist at a higher oxidation state, are the most common forms released during mining processes. Many technologies are capable of meeting the governmental discharge criteria for oxyanionic contaminants, but may possess limitations due to redox chemistry as well as the water matrices. An innovative technology was developed that can successfully reduce such aqueous forms generated during mining processes to a level below the discharge criteria. This paper discusses how an understanding of the sensitivities of this novel adsorbent towards these variations in water matrices and redox chemistry can be used to optimize its application.

Feb 27, 2013

By T. Lupek, M. Buxton, A. de Jong

"With regard to the EU funded project ‘Real-Time Mining’ a sensor-based acquisition, collection and transmission of data for the resource extraction process will be developed. The key concept promotes the change in paradigm from a discontinuous to a continuous process monitoring. Especially concerning material characterization, machine performance and underground positioning ‘Real-Time Mining’ will provide sensor solutions as well as the interfaces for integration, management and visualization of the collected data for a permanent updating process of the resource model with the aim of near real-time optimization of decisions. On the basis of ‘Real-Time Mining’-Output a permanent monitoring of costs can be performed as well in both, the installation and the production process of a mine. Due to the collected data in terms of machine performance connected with the underground positioning information added with personnel tracking and mine surveys a comprehensive overview of process performance is available. By evaluating those information in a specific manner costs per unit will arise for monitoring and possibly controlling actions. INTRODUCTION By having a look into the future of mineral extraction projects, a new challenge for the Ore Mining Industry will arise in the short and medium term. Due to the depletion of currently mined mineral reserves in addition to the persistently high demand of mineral raw materials, the extraction of complex reserves will be necessary. By characterizing such deposits as not constantly graded and geometrically varying, the extraction process, especially concerning the requirement of a minimized zero-value material handling, will become economically ineffective by utilizing the traditional mineral resource management methods. Regarding the state-of-the-art mineral resource management process along the mining value chain, an intermitted, discontinuous sequence of actions is applied (Figure 1). Recently data will be collected from drill hole cores. These rock samples are analyzed in a laboratory. Based on those analyses a resource model is created whereby unknown data between drill holes is interpolated. This resource model is the basis for all mine planning actions including the selection of the mining method, extraction sequencing and the prediction of the expected performance. With the start of the production, real conditions (concentrations of elements, hardness, stability, etc.) can be observed and measured. As the production process is running accordingly to the above described mine plan, the verification of the initial assumptions happens at the earliest after processing of the extracted material. Even if deviations between the predicted and the actual performance are now recognized, the execution of corrective actions is not possible anymore."

Jan 1, 2016

By A. Tarigan

The integration of the ESZ orebody and DOZ orebody resulted in a much larger footprint than the original DOZ Mine shape. The significant change in footprint geometry presented new cave front management challenges, specifically: longer undercut drifts. Using a constant blasting rate, more time is required to complete caving in each drift which ultimately influences the number of active faces at any point in time. The number of manageable active drifts is controlled by the planned square-meters of undercut blasting, lead/lag restrictions and other specific conditions such as the need to blast pre-charged explosives. In early 2008, an evaluation of the existing plan showed that significantly more active undercut drifts and longer cave fronts would occur in the next five years. Difficulties associated with the long cave fronts led to a decision to redesign the caving sequence. Several different boundary options based on operational, geotechnical and ore grade parameters were investigated. This paper describes the issues faced with long cave fronts, the constraints and requirements to effectively manage the caving sequence and the options considered to mitigate this situation.

Jan 1, 2010

By Saverio Agresti, Giuseppe Lunardi, Donato Basta, Roberto Trapasso

"At a distance of 10 years from the first application of the Nazzano Method, the widening under traffic of a tube of an existing motorway tunnel was realized near Ancona, along the A14 Motorway in Italy. This paper describes the works for the enlargement with conventional method of the second tube, very close to that already widened under traffic.This enlargement was realized very fast, taking into account the advantages of some interesting technological improvements of the Final Design proved in the first tube.INTRODUCTION TO THE WIDENING OF EXISTING MOTORWAY TUNNELSThe widening of a twin-bore motorway tunnel usually considers the double option of creating a third bore as an alternative or closure to traffic of one of the two bores with the resulting reduction in the level of service for users.On the contrary, the extension in situ of a road, motorway, railway or underground tunnel in the presence of traffic, made possible by an inspired idea of Prof. Pietro Lunardi, enables the level of service of the infrastructure to be maintained without the need to resort to alternative routes to create new permanent or temporary bores, not always feasible because of the lack of the necessary space.This construction technique, known as the ‘Nazzano Method’, is part of the technologies refined and offered by the ADECO-RS approach to tunnel design and construction (Lunardi P., 2008) which is increasingly used in the world, leading to the industrialisation of tunnelling (meaning respect for the times and costs set out during detailed design) both in conventional and mechanised (through TBM) excavations.The first true experimentation of the ‘Nazzano Method’ was carried out between 2004 and 2007 to enlarge the two-bore ‘Nazzano’ tunnel (Italy, Milan-Rome A1 motorway) in the presence of traffic, widening it to house from two to four lanes in each direction (Lunardi P. et al., 2007). Following the success achieved in this first application, the Nazzano Method was strengthened considering all the possible suggestions arising from the previous experience and then taken up to enlarge the north bore of the ‘Montedomini’ two-bore tunnel (Italy, Bologna-Taranto A14 motorway), in situ and the presence of traffic."

Jan 1, 2016

By P. Aparicio

The rheological properties of five kaolins, isostatically pressurized at 4 x10 Pa for 10 min in the presence/absence of water, was determined. Under dry conditions, measured viscosity values either decreased or remained the same. After treatment under wet conditions, measured viscosity values were 30-60% higher at high shear and 50-60% higher at low shear. These results correlate with variations in nanomorphology and structural order. Dry compaction degraded kaolinite crystals but wet-pressing appeared to cause an increase in the proportion of euhedral crystallites and a decrease in deformed crystals. Dry compaction decreased the low-defect phase proportion (ldp), but in contrast, the ldp in wet-treated kaolins remained constant or increased. Results show that hydrous pressure treatment produces a change in viscosity of kaolin suspensions, yielding the potential for improving paper coating performance, whereas anhydrous pressure treatment decreased or maintained the viscosity.

Jan 1, 2010