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By John W. Stevenson, Ted L. Sartain

Underground booster fan installations are currently employed in hundreds of coal mines throughout the world. Such installations, when properly designed and maintained, have proven to be safe and effective tools to provide desirable airflow volumes on sections or in areas of mines where the ventilation requirements exceed the capacity of the main fan system. In cases where an airshaft cannot be justified due to surface topography, depth of cover, or limited reserves a booster fan can serve the same purpose, be operational in a fraction of the time and at a substantially reduced cost. Booster fans are currently non-existent in U.S. coal mines. This is primarily due to lack of acceptance by the Mine Safety and Health Administration (MSHA), which has failed to acknowledge the merits of a booster fan system. Also, the absence of booster fan provisions in Part 75 of the federal regulations has led to the misconception that booster fans are legally prohibited in U.S. coal mines. In 1986, Jim Walter Resources, Inc. (JWR) developed and submitted to MSHA a plan to install and operate an underground booster fan at the No. 7 Mine. Detailed computer simulations were used to substantiate JWR1s position, that the booster fan could effectively provide the needed airflow on a developing section without adversely affecting ventilation in other areas of the mine. JWR also realized that numerous safeguards and operating procedures were essential for providing a safe system. Thus, safety features such as electrical interlocking, independent power supply, remote atmospheric monitoring, etc., were incorporated into the plan. This paper is a case-study that discusses JWR's proposed plan to install and operate an underground booster fan at No. 7 Mine. Unfortunately, MSHA's continued negative response has prevented implementation of the plan.

Jan 1, 1989

By A. C. du Preez

The separation of nickel and cobalt from calcium, magnesium and manganese by solvent extraction using synergistic mixtures of carboxylic acids was studied. Addition of certain viable synergists to commercially available tertiary branched carboxylic acids, such as Versatic 10 (Shell) or Neodecanoic acid (Exxon), produced large synergistic shifts (?pH50) in the pH50values for nickel, and small antagonistic shifts (negative ?pH50values) in the extraction of calcium. Under the initial test conditions used (0.50 M each of Neodecanoic acid and the Mintek synergist, in xylene) a large separation (pH50Ca? pH50Ni= 3.09 pH units) between nickel and calcium in their extraction from 1.00 M sodium nitrate solutions was obtained, compared with only 1.11 pH units in the absence of the synergist. The selectivity series for the extraction of divalent base metals from 0.333 M sodium sulphate solutions by 0.50 M Neodecanoic acid and 0.25 M of the Mintek synergist in C12-C13aliphatic diluent was found to lie in the order (with pH50values in parentheses): Cu(3.42) > Ni (5.08) > Zn (5.58) > Co (5.73) > Mn (6.62) > Ca (7.48) >Mg (8.25). In batch counter current experiments, a simulated leach liquor containing (in gL-1): Ni 5, Mg 5, Mn 2, Co 0.5, Ca 0.5, Cu 0.1and Zn 0.1 was contacted with the mixed extractant in three stages at unit phase ratio and an equilibrium pH of 5.9. The recovery of nickel was 99.9 per cent and that of cobalt was 84.7 per cent, whilst the co-extractions of manganese, calcium and magnesium were 2.7,1.5 and 0.04 per cent, respectively. The recovery of cobalt can be enhanced by employing a slightly higher pH, although this will also increase the extraction of manganese, calcium and magnesium somewhat. Nearly quantitative stripping (99 per cent) of nickel from the loaded organic phase was achieved in a single contact at an organic-to-aqueous phase ratio of 4 using a simulated spent electrolyte containing 39 gL-1sulphuric acid and 33 gL-1nickel,thereby producing an ?advance electrolyte? containing 57 gL-1nickelat pH 3.5. Loading of acid into the organic phase was very slight, amounting to only 0.002 M H+in contact with the above-mentioned spent electrolyte. Keywords: solvent extraction; synergism; nickel; calcium; carboxylic acids.

Jan 1, 2004

By Marek Dworzanowski

Dense medium separation (DMS) is critical to the operation of coal and diamond beneficiation plants. It is also utilised in iron ore, manganese, chromite and andalusite beneficiation as well as pre-concentration for platinum-bearing UG2 ore. Gravity concentration plays an important role in the processing of diamonds, coal, gold, platinum, titanium minerals, zircon, chromite, iron ore and manganese. The DMS and Gravity Concentration operations and technology in South Africa conference will focus on the operation of DMS and Gravity Concentration circuits in the South African Mining Industry. The current status of the technologies and equipment employed will be presented as well as future developments. The conference was set up to showcase South African DMS and Gravity Concentration operations and provide a forum where operators, technology and equipment suppliers can engage in knowledge sharing. The papers cover a wide spectrum of topics, including descriptions of operations, optimisation projects, new capital projects, equipment applications, process monitoring and process selection. Most commodities and unit processes associated with DMS and Gravity Concentration are covered. The conference venue was selected to be the CSIR Convention Centre in Pretoria. The CSIR has contributed to DMS research in South Africa and it is located not far from many coal, diamond, gold, platinum and chrome mines that extensively utilise DMS and Gravity Concentration in their beneficiation plants. I believe that the papers and presentations submitted for this conference will provide a valuable future reference for DMS and Gravity Concentration, thus making the work of all the contributors to this conference highly rewarding and worthwhile.

Jan 1, 2006

By Jerome F. Kuzmick

Condusions. From the work on aluminum powder, the following general con clusions can bc drawn: I. The physical properties of aluminum compacts, such as density. strength and ductility, increase with increasing pressure, up to the practicable pressure limits. 2. Good properties ill aluminum con pacts can be secured only by the use of high pressures, because it is neccssary to rupture the refractory oxide film on aluminum powder. 3. Considerable softening of the specimens occurs upon sintering. regardlers of the pressure used. General Conclusions 1. For relatively short-time sintering. molding pressure is a very important factor in the final physical properties of the sintered specimens. 2. The effect of pressure. is difierent for each metal, so that few general rules can be drawn that would apply to all metals. 3. In many cases, fur a particular metal powder and sintering temperature there is a critical pressure at which the best physical properties can be obtained. 4. The principles of cold work and in nealing and their effect on grain structure applied to massive metal also holds true for sintered metals. 5. Particle size, at least for electrolytic iron powder, does not have a. great effect on ultimate grain six. DISCUSSION [E. E, Schumacher presiding V.. V. Crane. *—I was particularly impressed with Dr. Kuzmick's work on tin IF not the illustration, particularly the Second one. a very good illustraition of hot preessing. in that

Jan 1, 1945

Jan 1, 1967

By P. H. Morris

The profile of a delta formed by fine-grained mineral processing wastes, disposed of as aqueous slurries by subaerial deposition from a pipeline, has a significant bearing on the volume that is available for waste and water storage in a given containment structure. Earlier field data and laboratory experiments suggested that mine waste delta profiles could be predicted with high levels of accuracy using data from small-scale laboratory deposition tests. The relationships between the profiles of full-size and laboratory-model deltas were analysed using the principles of kinematic similarity and a recent theory of delta formation based on engineering hydraulics. Measured profiles of full-size and model coal-mine tailings deltas are compared and the prediction of full-size profiles discussed. It is shown that the data-derived laboratory-model deltas are insufficient to allow accurate prediction of full-size delta profiles. Initial slope data or other, equivalent data for the full-size delta are also required

Apr 1, 1996

By W. W. Anderson, D. G. Girton

The photoluminescence of Pr, Nd, Ho, Er, Tm, and Yb in CdS, and Ho, Er, Tm, and Yb in ZnSe has been observed from crystals Prepared by diffusion using rare earth metals and an excess chalcogen pressure. For a given temperature, time, and chalcogen pressure the spectral characteristics were very reproducible from run to run, and the emission intensity for Nd, Er, and Yb in CdS was as high or higher than the best vapor phase doped crystals we have grown. For a few rare earths it was found that certain conditions of diffusion tend to yield optimum rare earth emission intensity with respect to the background lattice emission. Photoluminescence measwements of Yb in CdS as a function of depth gave a profile which was neither a Gaussian nor complementary error function. Part of the profile appears to arise from a fast component of the diffusion and the other part from a slow diffusing component. At 960°C and 33 atm S pressure, a com -plimentary error function approximation of the slow diffusing component gave a diffusion coefficient of D = 1.3 x 10-9 sq cm per sec. MOST of the studies of emission from rare earth ions in II-VI compounds have been reported on crystals doped during growth,1,2 although Kingsley and Aven prepared ZnSe:Er by diffusion for paramagnetic resonance and fluorescence studies. Pappalardo and Dietz prepared CdS:Yb by diffusion, but they made optical absorption measurements., We know of no study on the properties of rare earth diffusion in the II-VI compounds. To date we have diffused Pr, Nd, Ho, Er, Tm, and Yb into CdS, and Ho, Er, Tm, and Yb into ZnSe and observed the rare earth emission spectra. For a given temperature and chalcogen pressure, the emission characteristics are very reproducible from run to run and for Yb, Nd, and Er in CdS, as good as the best crystals we had prepared by doping during vapor phase growth.2 The emission of Pr, Ho, and Tm has been observed in CdS prepared by diffusion for the first time. Previous attempts2 to prepare these later three materials by vapor phase growth were unsuccessful. The problem of obtaining reproducible characteristics in II-VI semiconductor compound work is well known.5 Not only is it difficult to reproduce results from one laboratory to another but it is sometimes difficult to reproduce results from one growth run to another under ostensibly identical conditions within one laboratory. This situation has been particularly bothersome in research on the luminescence of rare earth activated ZnS1 and Cds2. Crystals from one vapor phase growth run would show very strong rare earth line emission while crystals from a nearly identical run would show no rare earth emission. It was also observed on occasion that the intensity of the rare earth emission was not constant over the entire volume of a single crystal. MATERIAL PREPARATION AND INSTRUMENTATION Vapor phase grown boules of CdS were supplied by Dow Corning. This material was characterized by a free electron concentration of n - 3.5 x 1015 cm-3 and Hall mobility of 350 sq cm per v sec at room temperature. There were microscopic voids and decorated precipitates in some samples. The precipitates annealed out at diffusion temperatures but the voids remained. Single crystal rectangular samples of mm dimensions were sawed from the boules. The ZnSe was polycrystalline, UHP grade from Eagle-Picher. Poly-crystalline samples were sawed from the ingots. The samples were lapped, polished on one side, etched in a solution of 0.5 M K2Cr2O7 in 16 N H2SO4, and thoroughly washed in distilled water. A sample, excess sulfur (or selenium), and 5 mg of rare earth metal (turnings) were sealed in a 3.6 cm3 quartz ampoule at about 2 X 10-5 torr. The high chalcogen pressure used (1 to 30 atm) prevented thermal etching of the crystals and affected the diffusivity and solubility of the rare earth ions in the crystal lattice. For meaningful or reproducible results, it is thus necessary to specify the vapor pressure at which the diffusion was carried out. It is assumed that a negligible amount of the chalcogen was used in the formation of rare earth sulfides or selenides Our sulfur vapor pressure calculations are based on data assuming S2, S6, and S, molecules only in which case the equilibrium constants are given by6 where the pressures are expressed in torr. Selenium vapor consists of a mixture of Se2, Se4, Se6, and Se6 molecules. The selenium vapor pressure was calculated using equilibrium constants given by The status of the rare earth source during diffusion is unknown, i.e., the partial pressures of the rare earth metal and of the rare earth chalcogenides has not been determined. All emission spectra were recorded at 77°K on a Perkin-Elmer model 98-G spectrometer using a 640 line per mm grating. No correction was made for the spectrometer and detector spectral sensitivity. Excitation was by means of an XBO 1600 w xenon arc

Jan 1, 1970

By R. Altindag

The rock brittleness is one of the most important rock properties that affect the drill-ability of rocks. It is supposed that the increase in rock brittleness causes the increase in penetration rate. The drill-ability of rocks depends on many factors. These factors can be separated as two parts depending on a machine, bit type, rotational speed, thrust, blow frequency, flushing, and rock properties, brittleness, compressive strength, structure, hardness, etc. In this paper, the relationship between brittleness and drill-ability index, which is used in the prediction analysis of the penetration rate of rotary blast hole drills, were examined using regression analysis. It is also seen that significant correlations exist between brittleness and the drill-ability index.

Jan 1, 2002

By Donald Leroux, Ralph Dahlke, Dave Scott, Finch. James A., Cesar O. Gomez

"The efficiency of the flotation process depends on how effectively air is dispersed into small bubbles. Bubble surface area flux - the surface area of bubbles per unit time per unit cross-section area of a cell - is emerging as the parameter to characterize gas dispersion. One of the approaches proposed to measure bubble surface area flux in industrial cells is based on the measurement of two variables: gas velocity and gas holdup, using separate sensors. Plant testing of the gas velocity sensor gave evidence of a series of operational problems which may be necessary to correct before attempting to characterize gas dispersion. Problems such as uneven air distribution within a cell and along a bank, faulty air and slurry valves detected during attempts to redistribute air, and poor control of pulp level and gas flow became evident. Detection of these problems from gas velocity measurements is illustrated.INTRODUCTIONBubble surface area flux is considered a key variable in the optimization of flotation circuit performance (Gorain et al., 1997; 1998). The Mineral Processing Group at McGill University has devised and developed a method for estimating bubble surface area flux in industrial flotation cells (Finch et al., 1999). The method is based on measuring gas holdup and superficial gas velocity using two separate sensors and applying drift flux analysis to estimate bubble size (Dobby et al., 1988; Banisi and Finch, 1994). With bubble size and superficial gas velocity known bubble surface area flux can be calculated.This method was selected by Noranda to characterize gas dispersion in cells as part of a program to model and optimize flotation circuit performance. However, initial testing at Brunswick Mine with the gas velocity sensor provided some unexpected results indicating operational problems and equipment malfunctions that needed to be addressed before systematic measurement of gas dispersion could be initiated.The subject of this communication is to illustrate the detection of these problems from gas velocity measurements. The line 3 Zn Cleaner circuit comprising four stages of Denver DR cells was the main subject of analysis, including the effect of correcting these problems on the metallurgical performance of the Zn 3rd cleaner bank of ten DRl 00 cells."

Jan 1, 2001

By Choon Kooi Quan

Water availability is essential for mining and minerals processing. To provide government and industry with recent data for water use planning and management, the Bureau of Mines canvassed a number of U.S. producers of nonfuel minerals to determine their water use in 1984. Data were analyzed and compared with previously published data in order to examine historical trends in water utilization in the nonfuel minerals industry and to estimate water requirements in the year 2000. Total water use in the domestic nonfuel minerals industry during 1984 was estimated at 2,267 billion gal, of which 571 billion gal was new water and 1,696 billion gal recirculated water. The largest users of water were the phosphate rock, iron ore, copper, sand and gravel, and crushed stone industries, together accounting for almost 90% of total used. More than one-half of all water was used in Florida, Michigan, and Minnesota. In the year 2000, total water use will amount to an estimated 2,679 billion gal, of which 810 billion gal will be new water and 1,869 billion gal recirculated water. Most of this water would be used in producing the foregoing suite of minerals,

Jan 1, 1988

Microorganisms are finding more use in the mineral industry, with extensive research efforts being reported in 1991. Most of these research efforts were presented in two major meetings, the SME Annual Meeting in Denver (February, 1991) and the Engineering Foundation Conference about Mineral Bioprocessing in Santa Barbara (June 1991). In addition, several articles were published in the IMM Transactions, Minerals and Metallurgical Processing and Water, Air. and Solid Pollution Journal. The literature can be categorized as: • Review articles presenting an overview of the activities in the use of biotechnology in mineral processing. • Research efforts into genetic manipulation of microorganisms to perform a specified job. • Studies in bioleaching of metals from different types of ores. • Biotreatment of wastes from the mineral industry including acidic mine waters, uranium tailings, cyanide destruction, etc. • Investigations into the role of microorganisms in the energy materials, such as oil, coal, tar sands, oil shales, etc. Smith (Mineral Bioprocessing Conference) presented a review of research efforts as well as practical applications of biotechnology in the mineral industry. In another article, Smith et al. (Minerals Engineering) emphasized that extensive fundamentals and applied research work should be pursued to explore the fundamentals, potential and practicality of the various possible uses of microorganisms in mineral engineering.

Jan 1, 1992

By F. G. Pickard

"The Strathcona Concentrator is one of three concentrators presently operated in the Sudbury District by the Nickel Division of Falconbridge Nickel Mines Limited. Production commenced in 1968 at a milling rate of 6,300 tons per operating day. Milling capacity was increased in 1970 to 7,200 tons per operating day. 7he ore contains iron, nickel and copper primarily in the form of pyrrhotite, pentlandite and chalcopyrite, while the common gangue minerals are feldspar, quartz, mica, talc and chlorite. The primary function of the concentrators is not only to liberate sulphides from silicate gangue minerals but also to separate pyrrhotite from the more valuable minerals pentlandite and chalcopyrite.SummaryExcessive wear on steel liners and blinding of grates in a regrind pebble mill of the Hardy Concentrator was corrected by the use of rubber liners and grates. The success of these resulted in their installation as original linings In all grinding units except the rod mills at the Strathcona Concentrator. The operation of rubber liners and grates when sized mine ore was used as the grinding medium was satisfactory confirming the Hardy Concentrator experience. Problems developed when the grinding medium was changed from sized mine ore to steel balls in that blinding of the grates occurred. This resulted in conversion of the units to overflow type mills through removal of the grates. The lifter bar life was significantly increased by using higher lifter bars.Grinding PracticeOperation of a regrind pebble mill commenced in 1961 in the Hardy Concentrator. This operation demonstrated the economic feasibility of using sized mine ore as grinding medium. Problems caused by excessive wear of metal liners and grates combined with blinding of the grates were corrected in 1964 through installation of rubber liners and grates."

Jan 1, 1974

By G. Luttrell

Coal preparation plants play an important role in modern society by providing high quality feeds for coal-fired utilities, industrial boilers and metallurgical coke facilities. Unfortunately, field data indicate that preparation plants are often not operated under optimum conditions, resulting in lower productivity and lost profits. In many cases, this shortcoming can be attributed to a failure by plant operators (i) to recognize the importance of correctly adjusting plant operating conditions to accommodate requirements dictated by coal sales agreements within different coal markets and (ii) to properly account for variations in product moisture with particle size across different plant circuits. This paper discusses the important influence of moisture constraints on preparation plant optimization and provides a case study to illustrate the potential gains that can be realized via proper understanding of plant moisture control.

Jan 1, 2009

By Ambarish Ghosh, Chitralekha Ghatak, Tanumaya Mitra, Tarun Sengupta, Sajib Das, Sankar Kumar Nath

"Currently construction of important structures like bridges, flyovers and high rise buildings in and around Kolkata are in full swing. These structures have mostly pile or well foundations. The design methodology and construction techniques are being employed keeping in view both the safety and economy of the project. The data presented in this investigation have been taken from Geotechnical Investigation report of Component B in connection with construction of Extradosed Cable Stayed Bridge over River Hooghly in Hooghly and Nadia district of West Bengal, India. The investigation site is located within close proximity of Eocene Hinge Zone which is being taken as the principal contributor of Earthquakes in and around Kolkata. Considering the importance of the project detailed and exhaustive geotechnical investigation has been carried out and site specific response spectra have been generated for analysis and design of the bridge. This paper presents site specific response spectra, liquefaction analysis and comparison of lateral load carrying capacity of pile using Winkler approach and IS 2911 guidelines.INTRODUCTIONPile foundations are used to transfer the load of the super structure through soft soil deposit to deeper bearing stratum by means of skin friction or end bearing or both. Pile foundations are regarded as a safe alternative for supporting structures in seismic areas and have been used for this purpose in non-liquefying as well as liquefying soils. But their design in case of potentially liquefiable soil is quite different from that of non liquefiable soil. In liquefiable soil the progressive buildup of excess pore water pressure will cause stiffness degradation and loss of strength which in turn will induce additional shear force and bending moment in the pile. The mechanism of pile behavior in liquefying soil has been investigated by several investigators in the recent years based on observations of pile performance during earthquakes and studies in the centrifuge and Shake Table tests. Exhaustive geotechnical investigation has been carried out along the proposed alignment of the Extradosed Cable Stayed Bridge i.e., along Baropara, Bansberia ROB, Ishwar Gupta Bridge, Saraswati River to collect disturbed as well as undisturbed soil sample, to develop average soil profile and to determine the design parameters. The proposed project site is very close to Eocene Hinge Zone, which is basically a strike slip fault, capable of generating an earthquake of Mw 6.7. Thus it is evident that the proposed Bridge needs to be designed considering the adverse geo-hydrological condition as well as the earthquake aspects needing special attention following the state-of-the-art technology as guided by relevant codes and published literatures. Considering the soil profile of these locations ground response analysis has been carried out using equivalent linear method to determine the site amplification. Site specific response spectra have been developed for the four zones and zone factors have been determined. The computed zone factors are 0.198g, 0.195g, 0.195g and 0.20g for the four zones respectively, much higher than the zone factor 0.16g, which is for zone III, as stipulated in IS 1893:2002."

Jan 1, 2015

By B. Samanta

A quality characteristic analysed through construction of the Shewhart control chart is required to be normally distributed. In mining applications, this assumption is often violated as many quality characteristics follow skewed or lognormal distribution. In this paper, two methods were investigated using a heuristic approach for setting up the control limits for a skewed population. Based on these approaches a Mode chart, and a Weighted Variance (WV) control charts were constructed. The performance of the proposed methods was compared with the normal based Shewhart method through a case study conducted in a surface mine supplying iron ore to a steel plant. A simulation study was also conducted to evaluate the effectiveness of the proposed methods over the Shewhart method. The study revealed that the Shewhart control charts generated more out of control alarms compared with the Mode and Weighted Variance control charts for a skewed population of Fe%. The simulation results also revealed that for extremely high skewed population, the WV control chart and Mode control chart provided higher probability of coverage than the Shewhart method; although the detection rate (probability of detection) of out of control condition for these methods was slightly reduced compared with Shewhart method.

Jan 1, 2004

THE Broken Hill mining field, approximately 31 miles in length, is at present being exploited by seven companies, viz. : North Broken Hill Limited, Junction North Broken Hill No Liability, Broken Hill Proprietary Block 14 Company, Broken Hill ProprietaryCompany Limited, Sulphide Corporation Limited, Broken Hill South Limited, and Zinc Corporation Limited.The variation in size and shape of the ore-bodies in the mines of these companies, together with the many alterations in pitch and dip, necessitates differences in methods of mining, each company working out its problem in its own particular way.In the matter of chute construction for the handling of the ore broken in the stopes, each mine belonging to the above companies has adopted a style particularly its own, though it may be said that one or two of the types approximate very closely to each other, slight minor differences only being noticed in the design. It is the purpose of this paper to give a brief description of the principal types of chutes now in use in th,e various mines on the field, and in doing so they may roughly be classified into three groups, viz:1. Bulk Chutes, 2. Circular Chutes, 3. Square-set Chutes.The Bulk type of chute is used in the North and British mines of the North Broken Hill Limited, the Central and Junction mines of the Sulphide Corporation, the South Blocks mine of the Zinc Corporation, and the Block 14 mine.The Circular type of chute is used by the Broken Hill South mine and the South Blocks mine.The Square-set chute is used in the Proprietary mine, the Junction North mine, and occasionally in other mines where the square set method of mining is a necessity, and more particularly as mullock passes.

Jan 1, 1925

By C. E. Wicks, J. E. Tress, F. E. Block

The Bureau of Mines investigated the effects of gamma radiation on materials and chemical reactions to obtain information that could be of value in modern metallurgical practices . Various combinations of metals and their ores and compounds were irradiated in attempts to effect reactions that might be applicable in the extraction and separation of metal values from minerals and The types of reactions studied included complexing of salts , decomposition of hydrated salts , metal chlorination reactions , leaching of ores and minerals , halogen exchange , and various reducing reactions . All irradiations were performed at the Materials Testing Reactor Gamma Facility of the U.S. Atomic Energy Commission at Idaho Falls , Idaho . Spent fuel elements were utilized as the source of the gamma radiation . Some irradiation - induced changes , ranging from mere color change to participation in chemical reactions , were noted . The greatest value of these investigations , however , was the experience acquired , which should be valuable in future explorations of similar nature .

Jan 1, 1964

By G. L. Oldright

[This paper is the fifth 4/ of a series of publications on smelting in the load blast furnace. The objects of this investigation are to determine the conditions obtaining within the blast furnace by direct experimentation, and to correlate the behavior of the furnace at various tines with the main factors governing the operation of the blast furnace, and metallurgical losses.]

Jan 1, 1929

By Lianhui Jia, Yali Han

"The key technologies of a large rectangular pipe jacking machine with dimensions of 10.12m × 7.27m (width x height) include selection of rectangular cross-section cutting modes, analysis on the strength and stiffness of the rectangular shield, integrated control of electro-hydraulic proportional thrust systems and ground conditioning for excavation are presented in detail in this paper. These key technologies have been successfully applied and verified on site during tunneling, providing a new concept for the building of large rectangular traffic and pedestrian tunnels in urban areas for the future.1 INTRODUCTIONIn the past, underground tunnels were mainly used for drainage, sewage, utilities, metro tunnel, etc. and most of them had circular cross-sections. Recently, as a result of economic development, gradually accelerating urbanization process and diminishing ground space, underground tunnels have already become a new trend for urban underground space utilization. Due to the heavy traffic flow, the demands for rectangular cross-section underground tunnels, such as pedestrian underpass and road tunnel, are increasing gradually.The Rectangular pipe jacking machine (hereinafter referred to as RPJM) was firstly developed in Japan for the construction of metro station, pedestrian underpass, underwater tunnel by-passes, etc. Kazunaki Kawai et al. introduced a RPJM developed and manufactured by KOMATSU in 2002 [1]. Tosikazu Kubota et al. confirmed the rectangular tunnels’ superiority to circular tunnels with regard to larger inner cross-section and lower construction cost in their RPJM construction reports [2]. Compared to circular pipe jacking machines, a RPJM also has the merits of a higher inner tunnel space utilization ratio and is able to excavate in shallow overburden areas. As shown in Figure 1, the effective area of a rectangular tunnel is more than 20% higher than that of an equivalent circular tunnel."

Jan 1, 2016

By L. K. Daneshmend

"Competitive pressures dictate that the mining industry moves to larger mobile underground haulage equipment with more advanced equipment mechanization, higher levels of autonomous operation of machines, and longer periods between access by maintenance personnel. Since such new machines will of necessity be more complex than existing designs, machine reliability has become a key issue in progressing toward advanced mobile underground haulage equipment. Reliability and maintainability models of such equipment are practically non-existent in the literature. This paper addresses the issue of reliability and maintainability of mobile underground haulage equipment on two fronts: reliability modelling to enhance decision making for maintenance planning; and reliability simulation to enable evaluation of more rigorous production planning scenarios. A case study from a gold mine in the Chilean Andes is presented, for which reliability models of mobile underground haulage equipment, specifically load-hauldump vehicles and underground haul trucks, are developed, and a reliability-based simulation implemented. IntroductionMaintenance accounts for 20% to 35% of the overall operating budget for a typical underground operation, and hence represents the largest portion of the mine’s controllable operating costs (Cutifani et al., 1996; Campbell, 1997; Goddard, 1998). This, coupled with the fact that industry today is faced with an ever more complex and demanding marketplace, has led to an increasing interest in methods to reduce maintenance costs.Although significant effort has gone into developing effective maintenance strategies for industry in general, application of these to the"

Jan 1, 2003