Search Documents

By Kevin G. Stricklin

Introduction Continuous monitoring techniques have been used in the US and abroad for many years. A continuous miner has a monitor that measures methane and automatically gives a warning if the methane exceeds 1%. It deenergizes the continuous mining machine automatically at a maximum concentration of 2%. Main fans are also continually monitored to ensure operation. Alarms may also be given at a remote location should a fan slow or stop. The systems being developed can continuously monitor various gases and equipment throughout the mine and transmit pertinent data to a surface monitoring station. At this station, conditions throughout the mine can be monitored and, in some instances, controlled. These are known as Mine Wide Monitoring Systems (MWMS). History The use of environmental monitoring systems began in 1976 when a federal court approved the petition of modification to use belt air at the face. The first mine to receive a modification did install a system to supplement existing safeguards. Later, the Mine Safety and Health Administration (MSHA) and the US Bureau of Mines (USBM) conducted tests dealing with the use of belt air. Findings from these tests are being used to set guidelines as requirements of a petition. These requirements include: • Velocity of air has to be 0.25 to 1.5 m/sec (50 to 300 fpm); • Monitors will be installed at each belt drive and tailpiece and at intervals not to exceed 610 m (2000 ft); and • An alarm level of 10 ppm, above the ambient level is appropriate. The early uses of environmental monitoring could only be used outby the last open crosscut. That may be a reason for an initial slow growth of these systems. In June 1982, MSHA began evaluating systems that could be used in returns to ensure that monitoring systems being used in areas where permissible equipment is required does not of itself pose an explosion hazard. This is known as the Mine Wide Monitoring Systems Evaluations and Sensor Classification program. The evaluations and classifications granted are based on electric currents and voltages. Use of mine wide monitoring systems The environmental aspect of MWMS in today's coal industry deals with carbon monoxide (CO), methane (CH4), and air velocity. Just as all mines are different and encounter different problems, the MWMS are diverse and can be used to provide necessary data in all areas of coal mines. Mine operators in an ultragassy seam, for example, may be concerned with monitoring methane, while a mine that used diesel equipment may want to continuously monitor for diesel contaminants. In a mine with roof fall problems, airflow monitors may be helpful as an indication of whether the air is flowing in its normal course and at its normal volume. Today's MWMS can monitor any or all of these parameters. Most systems can be expanded as mining needs require. For example, a mine is now being monitored for methane and five years from now CO monitoring would help increase safety. It may be possible to use the same system by adding additional equipment. In the US, 30 environmental monitoring systems were installed from May 1985 through May 1986. In 1984 and 1985, there were 38 and 44 environmental monitoring systems in operation, respectively. Due to mine closings, 11 of these are no longer in use. However, the number of mines using environmental monitoring systems increased to 63. Use of these systems are not limited to any geographic area or

Jan 9, 1987

By M. A. Rodrigues da Silva Enríquez

One of the rare consensual points among different resource-based economic analytical approaches refers to the strategic role of rent from mineral extraction, as a decisive tool to ensure that the temporary wealth generated in the present can turn into permanent income in the future. For this reason, evaluation, distribution and use of mining rent plays a central role in the sustainable development of mining cities. Brazilian legislation provides for this at the municipal level by means of participation in the financial results of mineral extraction accomplished in these municipalities, with the Financial Compensation for Mineral Exploration (CFEM). CFEM is a type of ad valorem royalty, which charges taxes of up to 3% of the net revenue of mineral production. However, legislation does not establish how these resources should be used. Therefore, there is wide variation in the use of CFEM income among Brazilian mining cities. A study from a sample of the 15 largest mining cities in eight Brazilian states made possible identification of two main patterns with regards to the use of CFEM which were labeled "sustained use" and " the pitfall of the single treasury." In that regard, this article discusses the pressuring factors that contribute to these patterns, as well as the institutional arrangements which may be more favorable to inducing more sustained use of CFEM.

Jan 1, 2011

By Jetson Lemos Ferreira

O presente estudo teve por objetivo verificar a independência tanto da Curva Limite de Tensão (CLT), quanto da Curva Limite de Deformação Plástica Efetiva (CLDPE) em relação à trajetória de deformação. Para tal, foram utilizadas Curvas Limite de Conformação (CLC) de aço livre de intersticiais (Interstitial Free - IF), determinadas, primeiramente, por meio de trajetórias lineares e, posteriormente, por trajetórias bi-lineares estabelecidas por níveis de pré-deformação nos modos de tração uniaxial e estiramento biaxial simétrico. As previsões da CLT e da CLDPE, calculadas a partir das deformações limites da CLC convencional em trajetórias lineares e bi-lineares, mostraram-se independentes em relação à trajetória de deformação. Entretanto, verificou-se que o critério de escoamento adotado tem grande influência na forma e posição destas curvas limites.

Aug 17, 2017

By T. T. Wang, T. H. Huang, S. S. Zhan

"Fractures with diverse features dominate the hydraulic behavior of fractured rocks and are one of the major subjects for hydrogeological characterization of a site. This study investigates curve patterns obtained by packed tests, and as well the influence of fracture features based on 59 sets of in situ packer tests with different fracture combinations and fracture features. The result shows that, in the example of Heshe site, neat and tidy fractures usually provide stable channel for water flow during testing, and the hydraulic properties of fractures infilled with breccia and mud may change during testing because of leaching and/or washed out of infilling breccia and mud. Different combinations of fractures with diverse features in packed test sections lead to different curve patterns for in situ hydrogeological tests. For groundwater flowing predominately through neat and tidy fractures, the pressure-discharge curve of modified Lugeon tests are usually linear curve pattern, and the pressure decrease while the discharge increase in pressure-discharge-time curves of single-hole double packer tests, which benefit statistically determining the transmissivity of dominant fracture sets. INTRODUCTIONFractures interlaced in rock masses are major channels for groundwater flow and generally account for the anisotropic and heterogeneous characteristics of permeability for fracture rocks. To describe reasonably the permeability of a fracture rock, the Discrete Fracture Network (DFN) approach and others with similar ideals have been developed. Many methodologies and associate equipment, for instance, the televiewer and the in situ hydrogeological test, have been proposed to investigate the spatial distribution and the transmissivity for different fracture sets, which are two main parameters necessary for the DFN or similar model simulation (Pearson & Money, 1977; Barker & Black, 1983; Hsieh et al., 1985; Bernard et al., 2006; Quinn et al., 2012). However, diverse outlooks for the pressure-discharge curves and the temporal pressure and associate temporal discharge curves often confuse the investigation results by significant deviations on derived permeability (Houlsby, 1976; Zlotnik, 1994; Royle, 2009; Camilo, 2010).Aiming on technical development for in situ hydrogeological tests and fracture investigation, an experimental well site with 10 wells has been established in Heshe in central Taiwan since 2011 (Wang et al., 2011; Song, 2012; Zhan et al., 2013). Extensive geological survey and well-hole scanning by a televiewer provide spatial distributions and outlooks of fractures in detail. Additionally, a series of Lugeon tests, double packer injection tests and pumping tests have been performed to investigate the permeability of fracture rocks, and dominate fracture sets as well. Based on the results obtained from the Heshe site, this study classifies the curve patterns of hydraulic packer tests. The features of fractures involved in packed sections for packer tests are then inspected in detail. Relationship between the curve patterns of hydraulic packer tests and associated features of corresponding fractures in rock are discussed and addressed accordingly."

Jan 1, 2015

By R J. Soriano, S Ciutina

The Masbate gold deposits are situated on the island of Masbate, 350 km south of Manila. A new plant was commissioned in April 2009. The grinding circuit consists of one semi-autogenous (SAG) mill Ø9.75 m × 4.27 m, two ball mills Ø5.6 m × 7.1 m and a pebble crushing circuit, which is usually called a SAG-ball mill-crusher configuration. The SAG mill was originally equipped with radial pulp lifters. The mill runs at fixed speed of 10.9 rev/min, which is approximately 80 per cent of critical speed (per cent CS). Due to the high speed of the mill the original radial design pulp lifters presented a high volume of recirculating load inside the chamber and consequently heavy wear on the outer circle (bottom pan).In order to address the high wear on the pulp lifters a number of avenues were considered in early 2011. The chosen solution was to change the geometry of pulp lifters from radial to curved design. The pre-existing drilling pattern on the discharge end of the mill was a major constraint. A number of designs were considered. The selection of the most suitable option was to be made based on 3D discrete element modelling (DEM) and smoothed particle hydrodynamic (SPH) simulations.The original radial design and two potential solutions for curved pulp lifters were simulated with 3D DEM and SPH software. The main three objectives were predicting the charge dynamics, the expected wear patterns and discharge efficiency. One of the solutions was chosen and implemented during 2012.Observations carried on after installation of the curved pulp lifters have confirmed, as expected, a reduction in wear intensity on the outer pulp lifters. In addition to this, at early stages of operation with curved pulp lifters, the mill operator noticed a reduction in energy consumed by the mill with no detrimental effect on mill performance.This paper is intended to further study the effect of curved pulp lifters on mill energy consumption.CITATION:Ciutina, S and Soriano, R J, 2014. Curved pulp lifters – can they save energy?, in Proceedings 12th AusIMM Mill Operators’ Conference 2014 , pp 109–116 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 1, 2014

By C. R. Kuzell

INTRODUCTION KNOWLEDGE of the thermal capacity of gases is of great importance in making metallurgical calculations. The metallurgist is, frequently called upon to investigate and determine furnace efficiencies in which the heat carried into or out of the furnace by gases is a large item in the heat balance. Not only do such problems present themselves in the determination of furnace efficiency, but also in the study of the application of heat is accessory apparatus, such as stoves, regenerators, waste-heat boilers, driers,.etc. The thermal effect of the use of excess air in the combustion of fuel, the theoretical temperatures of combustion, the quantity of heat in hot blast at various temperatures, the effect of hot blast on furnace temperatures, are a few more examples of frequently occurring calorific problems involving gases. So many are the applications of the data on the heat capacity of gases that the subject merits careful study. The heat in a gas maybe due to its heat of combustion, if it is a combustible gas, and to its temperature. The latter is called its sensible heat and is the heat absorbed or evolved by a gas as its temperature is raised or lowered. The heat of combustion of gases is well established and is commonly known. The values can be found in almost any mcdern treatise on metallurgy. The sensible heat of gases has not been so well established because it is in most cases a function of the temperature, and the values of specific heats of gases over a wide range of temperatures have only recently been determined. It is the purpose of this paper to deal with the sensible heat of gases.

Jan 8, 1914

By C. R. Kuzell

The Editor desires to call attention to the charts in the paper of the above title which were published in the August Bulletin on pages 2190 and 2191. It was impracticable to include in the Bulletin. charts of sufficient size to be used as working diagrams for the direct determination of operating values, but the Institute is prepared to furnish copies of these charts on a large-size scale, at a moderate cost, to those who desire to have them for this purpose. CORRECTIONS Page 2185, line 3. For "is accessory apparatus" read "in accessory. apparatus." Page 2188. Substitute for lines 11 and 12: Nitrogen, oxygen, carbon monoxide, Cp = 6.50 + 0.0010T Hydrogen, Cp = 6.50 + 0.0009T

Jan 9, 1914

By C. S. Parsons

Custom milling-plants have been operated successfully for a great many years on this continent. One of the outstanding examples in the United States is the Golden Cycle mill at Colorado Springs, which mills the gold-telluride ores from the Cripple Creek district. In eastern Canada, the Northern Custom Concentrators, Limited, at Cobalt, successfully treated the cobalt-silver ores of that area for a number of years. Flotation plants have entered the custom field in the past few years. The building of flotation concentrators to treat ores on a custom basis indicates the advance which has been made in flotation. In fact, three years ago it was considered almost impossible to treat successfully a mixture of miscellaneous ores by flotation. The methods used at that time were considered so delicate that any change, even in a single ore, would usually result in decreasing the effectiveness of the separation. Today we find four large custom flotation plants in the United States and one in Canada for treating complex lead-zinc ores from many different localities. The advent of these mills was brought about by the serious problem confronting the lead-smelting plants due to increasing amounts of zinc in the ores presented for treatment. It was necessary to penalize the mines shipping high-zinc ores. The penalty is justified, because high zinc in the lead blast-furnace charge not only decreases the tonnage of the furnace but increases the amount of flux necessary, as well as increasing the metal loss in the slag. It has been estimated that in the Salt Lake valley alone, 75,000,000 pounds of zinc was lost in the slag-dumps from the operations of three large lead blast-furnace plants. It has also been estimated that $150,000 worth of additional flux was required to slag this zinc. It was to avoid at least a part of this wste and to help maintain an ore supply that custom flotation concentrators were built by the smelters.

Jan 1, 1928

By Michael T. McCaffrey

The wide range of potential feed materials, process steps, and products in metallurgical facilities means that standard equipment might not be available to adequately meet the project technical and economic needs. Custom designed equipment should be considered only after rigorous research precludes purchasing standard equipment. However, the decision to use custom equipment introduces a new element of risk into the project. To manage the risk, custom equipment design should be developed through the same front end loading (FEL) phases as project development. If more than incremental development of custom equipment is required, appropriate test work or pilot trials are required to test key uncertainties. Important activities during custom equipment design include maintaining clearly defined performance objectives, conducting appropriate reviews, carefully crafting commercial and intellectual property agreements with design and fabrication partners, and assembling a multidisciplinary team with sufficient development expertise.

Jan 1, 2015

By R. B. Hopler

Explosives R&D has historically been motivated by coal mining. Whether to solve safety problems or to improve productivity and cost, the result has been the same: better explosives products and initiation systems. This process continues at an accelerated pace today due to the tools presently available to the explosives and mining industries.

Jan 1, 1993

By J. David Chapman

There are a variety of choices of materials for mineral extraction processing. Traditionally, end users have used metallic piping for fluid handling and little is known about the advantages (or limitations) of non-metallic piping systems. This presentation will review custom FRP pipe systems and their use in severe corrosive and erosive process streams. These systems can be designed to various pressure and temperature ratings and different components (such as resin and glass type) can be varied to suit the process conditions

As Coal Mining Areas develop, problems relating to strata control increase. The "easy" coal has been extracted and the future development lies in the direction of greater depths of cover and more difficult strata conditions. To provide solutions to the problems encountered the techniques of constructing and testing physical models have been developed and refined. With a sound knowledge of model theory allied to practical experience, mining research engineers use physical cemented material models to examine, assess and solve mining problems relateu to strata behaviour and environment. For a model to provide the answer to a particular mining problem it is essential that as much information as possible be obtained from the mine or area of a mine which the model is to represent. Details relating to the strata, geological malformations, and the stress environment must be collected and collated to ensure reliable results.

Jan 1, 1976

By Franz Kolmbauer

At Primetals Technologies Brazil Ltda. Rio de Janeiro Santa Cruz Workshop we electroplate mold coppers for continuous casting by tank plating. Tank plating submerges the copper in the bath of the plating solution. This is the most common method of plating and is applicable for both broadface and narrowface copper plates. Mold copper plates have a decisive impact on the product quality as well as the cost for maintenance and production. A perfect understanding of the operational influences on the plates and performance variables are the first step for the right selection of a copper plating method. Variable Hiper Coat keeps the Copper Plates 50% up to 100% longer in operation because of applying hardness on the Copper Plate where it is needed. Primetals Technologies Brazil provides the solution which meets and exceeds the requirements for todays and future demands.

Aug 16, 2017

By Daniel Hack

A few progressive mining software companies have recognized the benefit of broadening their capabilities to the sand and gravel (aggregate) industry. The most promising new developments have been designed for use with Surpac Vision, one of the world’s leading geological modeling, mine design, and production management systems. Surpac’s broad user-base, who have always had a propensity for customization, are now focusing on development of solutions in the Tool Command Language (Tcl), an interpreted scripting language. Surpac Software International made changes to TCL to add Surpac specific extensions, thus creating the Surpac Command Language (Scl). The Tcl interpreter, including Scl extensions, is bound into the Vision executable to provide a seamless interface to the data objects used internally by Vision, the GUI, and the 3D rendering system. Custom solutions can be incorporated as Vision extensions, or as stand alone-modules used in correlation with modeling, design, and planning functions.

Aug 25, 2002

To suppress the natural bacterial action in acid mine drainage (AMD), the major contributor to acid formation. Approach Recycle partially-treated affluent back to the source of AMD within a mine, or to the coal or coal-waste stockpile. This effectively eliminates any further biologically-promoted AMD by inhibiting catalyzed weathering or oxidation by acid-forming bacteria. How it Works AMO-type effluents can be largely reduced by "recycling" the acidic outflow back to the source of AMD within a mine or to the Input side of a waste pile to percolate through the reactive pyrite and bacteria mixture. The bacteria in the cell thrive on the oxidation of ferrous to ferric iron through the electron transfer, Fe2 +[=]Fe3 + + e. Its reaction product [s, therefore, essentially ferric iron. While small quantities of Fe3 + will not interfere with the exponential multiplication of the bacteria

Jan 1, 1982

By Johns A. L

The concept of the Melbourne Underground Rail Loop and the organ- isation to achieve its construction are covered in the companion papers (Reference 1, 2) and will not be repeated here. The Victorian Railways, as well as being the eventual operator of the Loop when it is completed by MURLA, have also been responsible as "Contractors" to MURLA for the construction of the "cut and cover" or "box" tunnels and related approach works located on existing Railway property. These tunnel connections link the existing suburban system to the new underground works. The following tabulation indicates the significant work volume involved in this cut and cover tunnelling exercise and which is covered in some detail by this paper.

Jan 1, 1981

Narrow vein mining, with enough challenge and also where the cutting edge technology can be applied, is still a very important and exciting portion of the mining industry. Based on the deposit characteristics, the most flexible mining method, cut and fill, has been being tested mining this high grade Northern Nevada property, Hollister, since the year of 2008. In the last three years, 254,000 tons of ore were hauled out of the portal and 23,000 feet of development were excavated underground with the winning of several safety and environmental awards. Together with mine geology, the essential segments include mining cycle, ground control, ventilation, grade control and backfill method in cut and fill stopes were covered in this paper.

Jan 1, 2012

By Sebastián H. Troncoso

Open pit mine planning is normally based on the selection of an economic envelope that has been generated by the Lerchs & Grossman algorithm, which requires individual economic valuation of each block of a geological block model. The selected envelope, usually called Final Pit, is later discretized in pushbacks and benches, which correspond finally to the fractions that the production schedule will allocate in time. This planning methodology has been widely used by the mining industry in countless projects to exploit open-pit mines, however, in many of the deposits can be found some undesirable elements such as arsenic, phosphates, ash among others that tend to reduce the value of elements of economic interest, either by disrupting the processes of concentration or as deemed impurities that affect the quality of the final product. Thus, a fair amount of blending would be required to capture the real value of the ore body. The traditional approach under estimates a block value by penalizing the block value by the amount of contaminant even when at the mine a set of blocks is amine at a time. This paper proposes a methodology for computing cut off grades over time that would maximize net present value allowing blending that should fulfill a set of metallurgical constraints. Preliminary results show significant increases in value and reserves quantity, questioning the use of fixed cut-off grades in generating a production schedule when blending applies to fulfill a set of geometallurgical constraints. Finally, the model allows the authors to show the importance of having adequate planning tools that will lead to the ability to look at the potential economic value of a mineral deposit.

Oct 1, 2009

By Sitotaw Y. Fantaye

"The first segment of the Second Avenue Subway extension is approaching construction completion. The new extension will operate along Second Avenue from 96th Street to 63rd Street, where it will divert west along the existing 63rd Street line, stopping at the Lexington Avenue/63rd Street Station. The new line will have stateof-the-art stations at 96th, 86th, 72nd and 63rd streets.Most of the two-track, twin-tunnel subway was constructed using bored tunnel methods (Figure 1), with a tunnel boring machine (TBM). The launch and retrieving box of the TBM was strategically located at the south end of the 96th Street Station where bedrock exists approximately 70 ft (21.3 m) below street level. The TBM launch box and the 96th Street Station (Figure 2), including the ancillary facilities adjacent to the station, were constructed by the cut-and-cover method. The cut-and-cover work required the contractor to design and implement a stiff, tightlybraced retaining wall, approximately 100 ft (30.5 m) long, to tie the existing tunnel constructed in the 1970s to the new station, temporary street decking over the entire excavation, and a wide range of excavation support systems at various locations.The cut-and-cover construction posed significant challenges including: installation of street decking on busy Second Avenue, relocation and suspension of the myriad utilities beneath the streets, and configuration of a lateral support system that would minimize movement of adjacent structures but not slow down excavation activities. This article describes the innovative solutions developed to manage and facilitate safe and efficient construction without disrupting Second Avenue, a major southbound one-way thoroughfare.The work was performed in several phases involving: (1) preconstruction condition survey of existing buildings, (2) installation of instrumentation and monitoring, (3) major utility relocation efforts to move vital utilities from within the alignment of the slurry wall on both the east and west sides of the avenue, (4) implementation of maintenance and protection of traffic plans, (5) installation of temporary street decking across the entire avenue and over the excavation to allow an orderly movement of traffic and pedestrians, (6) staged excavation and installation of an intricate temporary bracing system beneath the decking (7) step-by-step construction of the new subway station’s structure and (8) staged removal of the bracing as the structure gained sufficient strength to resist the lateral loads. The main focus in this article is the design and construction of the temporary street decking and lateral bracing systems; the utility suspension system and the north tie-in that allowed the daunting task of excavation and construction of a new subway station in bustling New York City, with minimal disruption to the community, businesses and everyday traffic."

Jan 1, 2016

By Joel K. Waterland

GENERAL DESCRIPTION Homestake Mining Co.'s operations are at Lead, SD. Production from the various methods used are: 1 155 753 t/a (1,274,000 stpy) by open cut-and-fill, 68 039 t/a (75,000 stpy) by square set cut-and-fill, 144242 t/a (159,000 stpy) by shrinkage stoping, 107 048 t/ a (118,000 stpy) by blasthole stoping, and 67 132 t/a (74,000 stpy) in development work for a total of 1 542 214 t/a (1,700,000 stpy). Mining takes place from the 616-m (2000-ft) level to the 2073-m (6800 ft) level (Fig. 1). The average travel time to the stope is 45 min. GENERAL ORE BODY REQUIREMENTS AND LIMITATIONS Size, Shape, and Dip of Ore Body Six major ledges varying from 914 m (3000 ft) long by 228.6 m (750 ft) wide to 305 m (1000 ft) long by 122 m (400 ft) wide are mined. Within these ledges are irregular-shaped areas of varying sizes. These ledges dip at approximately 1.2 rad (70°) to the east and plunge to the south from 0.26 to 1.57 rad (15° to 90°). Ground Conditions The ore is cummingtonite (chlorite schist) which is very competent except for major bedding planes and fracture patterns. The footwall is a slate but because of the dip presents very few problems. The hanging wall is also a slate which because of the dip and bedding is very weak and requires considerable rockbolting. No problem has been encountered with rock bursts to a depth of 2438 m (8000 ft). Ore Value The ore values vary somewhat from ledge to ledge, but the average ore delivered to the mill is approxi¬mately 6.2 g (0.2 oz) of gold per ton. A small amount of silver is the only byproduct of this operation. Annual production of gold is approximately 10 575 183 g (340,000 troy oz). Production Requirements The mine has a mill capacity of approximately 1 723 651 t (1,900,000 st) but because of several fac¬tors (manpower, depth, etc.) this mill capacity has not been attainable for the past several years.

Jan 1, 1982