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By J. L. Carr

Continuous mining machines are extensively used in the underground coal mining industry. These machines are typically remote-controlled, and severe injuries and fatalities occur every year when a miner is struck or pinned by the machine. Proximity detection systems offer a means to prevent these types of injuries and fatalities by sensing the presence of a miner and disabling machine motion. Researchers at the National Institute for Occupational Safety and Health (NIOSH)have developed the Intelligent Proximity Detection (iPD) system to provide enhanced protection while minimizing false alarms. The iPD system uses a set of pre-defined rules to determine which machine motions are safe and which would present a potential hazard, and automatically disables only the potentially hazardous motions. This system has been installed and tested on a Joy 14CM continuous mining machine at the NIOSH Office of Mine Safety and Health Research in Pittsburgh. Under laboratory conditions, the achievable accuracy and performance of the iPD system has been quantified with respect to a number of variables including position of the conveyor boom, presence of the machine?s trailing cable, and orientation of the miner-wearable component. Disclaimer: The findings and conclusions in this report are those of the author(s) and do not necessarily represent the views of the National Institute for Occupational Safety and Health. Reference to specific brand names does not imply endorsement by the National Institute for Occupational Safety and Health.

Feb 27, 2013

By Michael J. Sapko, Gregory M. Green, Kenneth L. Cashdollar

The National Institute for Occupational Safety and Health (NIOSH) and the Mine Safety and Health Administration (MSHA) conducted a joint survey to determine the range of coal particle sizes found in dust samples collected from intake airways of US coal mines. The last comprehensive survey of this type was performed in the 1920s. The size of the coal dust is relevant to the amount of rock dust required to inert the coal dust, with more rock dust needed to inert finer sizes of coal dust. Dust samples were collected by MSHA inspectors from several mines in each of MSHA's 10 bituminous Coal Mine Safety and Health Districts. Samples were normally collected in several intakes at each mine. The laboratory analysis procedures included acid leaching of the sample to remove the limestone rock dust, sonic sieving to determine the dust size, and low-temperature ashing of the sieved fractions to correct for any remaining incombustible matter. The results indicate that particle sizes of mine coal dust in intake airways are finer than those measured in the 1920s. This finer size coal dust in intake airways would require more incombustible matter to be effectively inerted than the 65% incombustible specified in current regulations.

By R. P. Vinson, Abdurrahman Cetinbas, Joseph Cervik, M. G. Zabetakis

The effect of water infusion on the flow of methane and on the production of dust was investigated at an active face in the Pittsburgh coalbed. The average total flow of methane at the face decreased by approximately 79 percent, whereas the flow from the ribs increased about 24 percent after infusion. On the day after infusion, dust concentrations appear to have been reduced; however, the presence of large quantities of rock dust obscured the results on the following days.

Jan 1, 1972

By P Bellairs

The Hamersley Province is located 1000km to the North of Perth the Capital City of Western Australia and is of major economic significance due to the mining of extensive deposits of Haematitic Iron Ore for both domestic and export use. A small but significant proportion of the waste associated with these deposits presents problems due to its ability to spontaneously combust and react with explosives resulting in premature detonations.

Jan 1, 1996

By Thierry Bernard, J. M. Laboz

2000 HIGH-TECH SEMINAR Blasting Technology, Instrumentation and Explosives Applications

Jan 1, 2000

Whether you are an employee, contractor or consultant working in the mineral industry, there are pressures to deliver the best possible performance. Technical professionals are usually driven by an internal desire to perform to a high standard because of personal pride in their profession, but there are an increasing number of external requirements to demonstrate that the actions taken were based upon reasonable grounds and that the work conformed to current best practice. People expect these best practice procedures to be followed and governments are now requiring those tendering for contracts to be registered in some way and to be participants in quality assurance schemes. One is not immune to these pressures just because you are working in a less legislatively sophisticated developing country in the circum-Pacific rim (pacrim) region.   Among the external pressures are the general ethical requirements of the professional body to which the person usually belongs, e.g. The Australasian Institute of Mining and Metallurgy (AusIMM), which are further elaborated upon in various Codes and Guidelines on specific matters, e.g. JORC (ore reserves reports) and VALMIN (assessment and valuation reports). These are outlined and discussed. Also, AusIMM's Chartered Practicing Status (CPS) Proposal is outlined in the context of other Pacrim countries approach to registering of technical professionals, which is a way of ensuring that minimum standards of qualifications, experience, competence and repute are demonstrable to ones employer (or client), peers and the wider community, including government.   Today, in the external working scene, there are many laws (particularly those applicable to the corporate and environmental spheres), with which contractors/consultants and even employees must fully comply, or else face criminal sanctions involving huge fines and imprisonment. These, too, are outlined and discussed. One must be able to mount a due diligence defence to avoid or mitigate these consequences.   Personal liability in the context of the day-to-day performance of one's duties has thus become a major concern to the technical professional and the ways in which it can be ameliorated, or insured against, are described. However, for some mineral industry practitioners, the problem is exacerbated because. of their general ignorance of the extent of their personal liability exposure. This paper intends to address this ignorance and to heighten general awareness of personal liability issues, as well as proposing some simple ways to limit this liability.

Jan 1, 1995

Jan 1, 1967

By Fred D. DeVaney, C. W. Ambler

"Copper sulphate is a common flotation reagent for blende ores. Metallic iron also is present in the mill circuit, and a reaction between the iron and the salt would be in accord with well-known chemistry. The abundance of metallic iron in a flotation feed may be noted by even perfunctory examination. First of all the mine contributes metallic iron, then the coarse-crushing machines add their share, and finally the fine-grinding medium its portion. If the grinding is with cast-iron balls the amount of metallics is greater than when steel is used. Thus it is that much more metallic iron is present than would be indicated by noting the ball consumption. An estimate that the total amount of metallics is twice that supplied by the balls and liners might not be far amiss.That copper sulphate plates out on iron in an acid solution is well known, but since flotation is practiced commonly in solutions where acid has not been added this reaction has not been given sufficient thought.This problem has been the basis of a study undertaken jointly by the Mississippi Valley Station of the United States Bureau of Mines and the Missouri School of Mines and Metallurgy, at Rolla, Missouri. Its importance may be understood better when the tonnage of zinc ores now being treated by flotation in this country is considered. According to Gaudin4 5,536,244 tons of zinc or were treated by flotation during 1927. In these operations copper sulphate was employed as an activating agent; the amount per ton averaged 0.81 pound for straight sulphide zinc ores and 1.16 pounds for complex ores. Since such large quantities of zinc ore are treated by flotation and since metallic iron is always present, the importance of studying their reactions on each other and the effect of their reaction"

Dec 1, 1929

By Gaoming Wang

Outline 1. The Gangdese porphyry Cu-Mo belt 1.1 Regional geological background 1.2 Cu-Mo-bearing porphyries 1.3 Mineralization and alteration 2. Dating methods and results 2.1 Qulong porphyry 2.2 other porphyries 3. Geodynamic implications 4. Conclusions 5. Acknowledgements

May 1, 2004

By H. Boghosian

This paper presents the design and construction of a deep basement in a steeply sloping site in glacial till in Glasgow city centre. Existing foundations, adjacent structures and services, in tandem with asymmetric loading, presented particular challenges in the planning, execution and design of the project. The construction methods and temporary works, analysis by the Finite Element method and monitoring carried out are all described.

Jan 1, 2006

By Derek J. Cyr

Climate has an immense impact on the properties of Athabasca oil sands and the ease or difficulty with which it is excavated and extracted. During the winter months, exposed oil sands surfaces freeze. When hydraulic and electric shovels used in the various operations in the Fort McMurray area excavate the benches, large frozen lumps are created. These lumps are either destined for a lump dump where increased costs are incurred due to rehandle, or they are sent to the primary crushers where they can cause significant downtimes by jamming the crusher. The crusher down time can sometimes be in the order of hours of lost production. Studies on data from two consecutive winters at Syncrude Canada?s North Mine show a high correlation between climate and the generation of frozen oil sands lumps. Temperature, ground cover, traffic, bench exposure time, oil sands grade and moisture content all contribute to this problem. A 1D frost penetration model was used to predict the depth of frost expected in oil sands and the corresponding likelihood of frozen oil sands lumps. To combat the challenge of frozen lump generation, a number of proactive and reactive measures can be taken: artificial snow, shallow ponds, scheduling, blasting or ripping.

May 1, 2004

By S Jokanovic

At New Zealand Steel MiningÆs Waikato North Head operation a Bucket Wheel Excavator û shiftable conveyor mining system is used to excavate titanomagnetite bearing sand and clay. The system utilises two Bucket Wheel Excavators and two Beltwagons with a two shiftable bench conveyors and two common trunk conveyors to deliver material to a processing plant. The original system was commissioned in 1984 as a high capacity, low cost method of excavating. In 1996 a second Beltwagon was purchased, increasing the flexibility of the mining system.

Jan 1, 2002

Investigation on Multicomponent Semi-Autogenous Grinding

Sep 13, 2010

By Fred N. Kissell

In This Chapter [Instruments available to measure methane in mines and tunnels Using a portable detector in both accessible and restricted spaces Machine-mounted monitors: placement and response time Calibration of catalytic detectors for different gases and Misinterpreting warning signs This chapter gives guidelines for methane measurement in mines and tunnels. The emphasis is on the measurement procedure and the interpretation of the measurement rather than on the instrument itself.] The failure to properly sample for methane is a major contributing factor to methane explosion risk. Sampling errors are most likely to occur at mines or tunnels where the presence of methane is not suspected or during nonroutine tasks at mines or tunnels known to have gas. More specific information on methane sampling at continuous miner sections is in Chapter 3. Chapters 4 and 5 discuss sampling at longwall sections, and Chapter 14 discusses sampling at tunnels. METHANE DETECTORS FOR MINING Many models of gas detectors are available to measure methane concentrations, as well as most of the other contaminant gases found in mines and tunnels. An example is the iTX Multi-Gas Monitor, a portable gas detector available from Industrial Scientific Corp., Oakdale, PA. This handheld instrument measures several gases simultaneously. The cost (2004) ranges from $1,300 to $2,200, depending on the number of gases measured. Similar instruments are available from other manufacturers. Most methane detectors used in mining use a catalytic heat of combustion sensor to detect methane and other combustible gases. These have been proven through many years of reliable operation. For detection of methane, proper operation of catalytic heat of combustion sensors

Jan 6, 2006

By E. Ghali, W. Zhang, C. Su, N. Sorour, G. Houlachi

"Zinc electrowinning process is sensitive to the presence of metallic impurities such as lead ions that could substantially and negatively affect the power consumption and surface morphology. Effect of various concentrations of manganese ions and traces of lead ions up to 2.5 mg L-1 added to the electrolyte during electrowinning have been investigated by electrochemical polarization techniques such as galvanostatic, cyclic voltammetry and potentiodynamic. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) were applied to examine the surface morphology and crystallographic orientation, respectively. Microwave plasma-atomic emission spectrometry has been used to determine the lead content in the deposit and in the electrolyte after electrodeposition. It was found that lead ions added to the zinc electrolyte led to the increase of cathodic overpotential and current efficiencies of zinc deposit. However, addition of Mn2+ into the zinc electrolyte resulted in the decrease of cathodic potential and current efficiency of zinc deposit. It can be stated as example that galvanostatic polarisation at 40?C and 52.5 mA cm-2 in presence of lead up to 0.1-0.2 mg L-1 in the electrolyte and 8-12 g L-1 Mn could be better considered as practical working parameters for electrowinning process.INTRODUCTIONApproximately 85% of the global production of zinc metal is produced by electrolytic process (Sinclair, 2005). The main goal of the zinc plant is to obtain pure zinc deposits with high current efficiencies. Smooth and pure deposits with high current efficiency (CE) are always obtained from pure electrolytes (Alfantazi & Dreisinger, 2001). The presence of metallic impurities in the zinc sulphate electrolyte is a major problem for the zinc electrowinning industry, since decreases in current efficiency, changes in deposit morphology and cathodic polarization are observed for electrolytes containing small concentrations of impurities (Ault & Frazer, 1988; Muresan, Maurin, Oniciu & Gaga, 1996). Low level concentrations as parts per million of these impurities are reported to influence negatively the zinc electrodeposition (Beshore, Flori, Schade & O'Keefe, 1987)."

Jan 1, 2016

By T. R. Ingraham

The thermal decomposition of cupric sulfate and of cupric oxysulfate has been examined by deter-mining the equilibrium gas pressure generated over each pure compound. The equilibrium data have been used to calculate the thermodynamic properties of both compounds, and the results have been combined with previously published data to establish a predominance-volume diagram for the Cu-S-O system over the normal range of roasting temperature and gas composition used in the treatment of copper minerals. Copper oxysulfate recrystal-lizes at 1100°K with an apparently irreversible en-dothermic heat requirement of 2.9 * 0.3 kcal per mole. WHEN mixed sulfide minerals containing copper are roasted, either of two procedures may be followed, depending on the nature of the other metals. In the first procedure, the roasting is controlled to produce a maximum amount of water-soluble copper sulfate which may be removed selectively from the water-insoluble compounds of the other metals. In the second, control is directed toward the production of water-soluble sulfates of the other metals and an insoluble salt of copper. Effective control of either of these processes would be enhanced by knowledge of the thermal stability of cupric sulfate and of cupric oxysulfate. In this paper, established data for the thermal stability of cuprous and cupric sulfide and of cuprous and cupric oxide will be combined with new data for the therma1 stability of cupric sulfate and cupric oxysulfate, to designate the volumes of stability of the significant compounds in the Cu-S-O system in the temperature range 750° to 950°K. EXPERIMENTAL Materials, Apparatus, and Procedure. The copper source material used in all experiments was Fisher Certified Reagent Grade "anhydrous" cupric sulfate, for which the following analysis was supplied by the manufacturer: chloride, 0.002 pct; alkalies and earths, 0.2 pct; insoluble, 0.002 pct; iron, 0.020 pct. Cupric oxysulfate was prepared from the normal sulfate by two procedures. In the first, equimolar quantities of cupric oxide (prepared by decomposition of the sulfate) and cupric sulfate were ground together and heated under vacuum in a sealed silica vessel at 800°C. This procedure was subject to failure because of explosion of the silica vessels due to the pressure of the final traces of water released from the sulfate on the initiation of its decomposition. The second procedure involved roasting the cupric sulfate, with frequent rabbling, in a muffle furnace at 725°C for a period of 48 hr. This produced an excellent product, which was confirmed as copper oxysulfate by X-ray and chemical analyses. The experimental technique used was that of measuring the total pressure exerted by the sulfur trioxide, sulfur dioxide, and oxygen produced by the following reactions: 2 CuS04 = cuo • CuSO4 + SO3 [1] cuo . CuSO4 = 2 cuo + SO3 [2] SO3= SO2 + 1/2 O2 [3] The apparatus used in the experiments has been described previously.1-3 Its main feature of a U-tube mercury manometer in which the mercury is protected from corrosion by enclosure in a flexible Pyrex bellows. Before beginning a run, the interior of the apparatus, including the bellows-manometer and all connecting tubing, was thoroughly washed with hydrochloric acid and distilled water to remove any

Jan 1, 1965

By Judy K. Todd

Double benching has been utilized as an excavation technique in open pit mines for many years. This process involves drilling, blasting, and excavating the material for the design bench height. A second bench is then excavated without the creation of a catch bench, i.e. only minimal offset from the first bench face is allowed when drilling off the second bench. The result is a double high bench face or double bench. When drilling off the second bench, the offset of the drill from the bench face projects the lower bench face into the pit up to an extra five meters. This reduces the maximum attainable bench angle, enhances the probability of rock escaping the catch bench and increases the overall strip ratio. The generally utilized process of trim blasting also can impact on the final bench profile by contributing to blast damage of the face. BHP Billiton Diamonds Inc., Ekati Mine Diamond MineTM, has pioneered the usage of a technique that eliminates this offset. Double benching is accomplished by drilling a single, 30m pre-shear (two 15m benches) to define and protect the final bench profile. This article provides a comparison of the attained face angles obtained in the field utilizing both of the above methods, as well as a comparison with the analytically predicted angles prior to excavation.

May 1, 2002

By Kjell Karlsrud

"Abstract New semi-empirical design procedures for the determination of ultimate shaft friction and load-displacement response of axially loaded piles in clay are proposed. Hereunder also prediction of how the capacity will build up with time following the pile installation, primarily as result of reconsolidation. A main basis for developing the new procedures was detailed review and re-assessment of results from a series pile load test programs published over the past 30 years on piles well instrumented to monitor soil- and pore pressures as well as load distribution along the pile shafts. Two new alternative procedures are proposed for predicting the ultimate shaft friction; a-approach using the normalised undrained strength based on direct simple shear tests as a main correlation parameter, and ß-approach using the overconsolidation ratio, OCR. Both approaches include the effects of the plasticity index of the clay, Ip, which is shown to have an especially large impact on the correlations when Ip<25. It is recommended to use both methods in design practice, and select design values for the ultimate shaft friction that represents an average for the two methods. Pile diameter, length or stiffness, or whether the pile is open- or closed-ended seem to have little impact on the shaft friction. However, a moderate effect of pile length or flexibility on the total ultimate pile capacity comes out of the proposed t-z curves, which include some post-peak reduction. The proposed procedure for predicting the time for set-up is based on linear radial consolidation theory. The main input parameters are the insitu permeability and virgin modulus number (or virgin compression index) of the undisturbed clay. The same basic formula and correlations are applicable to both open and closed-ended or partially plugging piles.IntroductionThe design procedures presented herein are primarily based on observations and data collected in connection with “fully instrumented” pile testing programs that the author has been responsible for or has become involved with over the past 40 years, or that have been found in the literature.It was a pre-requisite for the test programs included that there were sufficient high quality soil data available to give a reliable determination of the true in-situ strength and compressibility characteristics of the clay deposits. The soil conditions range from soft NC clays with undrained shear strength down to about 15 kPa, to very stiff clays with undrained shear strength up to about 500 kPa and OCR up to 25. The plasticity index of the clays mostly lies in range 12 to 60 %."

Jan 1, 2014

By Juan Lucero

Como consecuencia de los factores externos e internos, las empresas mineras necesitan ser más eficaces a través de la implementación de nuevas tecnologías e informática. En este sentido, la compañía minera Milpo disminuye los costos de hardware para así generar un control de operaciones más minucioso, automatizado y oportuno. Los principales logros obtenidos son el control detallado de las operaciones, los sistemas operativos son la base para obtener los costos operativos, una mejor formulación y control presupuestal, control de servicios de terceros y el de los sistemas integrados.

Sep 13, 2001

By Calvin Konya, Anthony Konya

State and Federal construction specifications require the Blasting Contractor to prepare a Master Blasting Plan which is reviewed by the Owner’s Representative. The Master Blasting Plan requires the Contractor to submit the design of a typical blast. Most blasting specifications also require the Blasting Contractor to submit Daily Blasting Plans. The Master Blasting Plan and the Daily Blasting Plan require that the Blasting Contractor also submit the types and quantities of explosives and initiators used. The specifications also request that the Blasting Contractor submit the pounds of explosive used per delay for both production and presplit blasts. The Blasting Contractor may also be required to predict the anticipated ground vibration and air overpressure levels for the proposed blasts. There are equations that can be used to predict the ground vibration. There are also equations that can be used to predict the air overpressure levels. The data for these equations were primarily derived from quarry and surface coal mine and some construction blasts. Data from major construction projects were analyzed in this study to determine new air overpressure propagation equations for construction blasting. These new prediction equations compare calculated results analyzed from field data with other existing air overpressure prediction equations. Production blasting air overpressure values are also compared to air overpressure from presplitting

Jan 1, 2015