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The disasters between 1920 and 1979 in coal mines in Queensland and New South Wales due to underground fire, gas or coal dust explosion or to gas or coal outbursts, have been assessed. The evidence relating to disasters caused by gas explosion points strongly to divergence from safe mining practice as the main cause. There is a need for greater training and education of personnel, closer analysis of gas reports, better monitoring and testing procedures, improved ventilation standards and a policy where safe working practice is actively encouraged. Conditions in the New South Wales occurrences of gas explosion were similar to those at Collinsville, Queensland in that dykes, igneous sills, burnt out coal and faulting were common to all. Information on outbursts indicates that contributing factors were intrusions, depth of cover, fault zones and other geological disturbances, methods of work, pressure and type of gas.

Jan 1, 1982

The new legislative regime applying to the mining industry has been in force for nearly two years. However the parameters for the permits required under the Crown. Minerals Act 1991 and the resource consents required under the Resource Management Act 1991 are still being established. Mining operators will benefit from participating in the development of policies and plans currently being formulated by local authorities. The Energy Legislation Amendment Bill currently before the House contains amendments to the Crown Minerals Act to clarify points of uncertainty and to reduce transaction costs where possible.

Jan 1, 1993

By Ryan C. Linthicum

A system of steel sheeting and multiple levels of high capacity double corrosion protected soil anchors were used to restrain a major slope failure that occurred at the base of the Watchung Mountains mid-way through construction of a 650,000 SF retail center along Route 22 in Watchung, New Jersey. The implementation of a design-build earth retaining structure was necessary to stabilize and repair the disturbed mountainside in a timely fashion to permit completion of the retail center on a fast track schedule. The tied back steel sheetpile wall was approximately 2,000 feet long and varied in height from 12 to 25 feet. The hillside extended approximately 350 feet above and 600 feet beyond the wall with the main failure scarp extending 50 feet above and 90 feet beyond. The wall was constructed in a top-down manner and required the installation of 475 anchors to resist loads of up to 70 kips/ft produced by the creeping hillside and groundwater flows from both a series of springs and steady state seepage through an inclined zone of fine sand. Incorporation of a unique tie point connection eliminated the need for a waler, facilitating and simplifying modifications to anchor locations based on anchor load test results and conditions encountered during construction. Post grouting also proved to be an essential element in the successful construction. This paper presents the design and the construction methods used to restrain the significant earth lateral loads produced by a slope failure using steel sheeting tied back with high capacity soil anchors with anchor loads distributed to the sheeting through a unique tie point connection on a fast track schedule. Installation techniques, testing programs, and construction quality control are also discussed.

Jan 1, 2003

By T Hughes

Upward pressure on all mining operations is coming from the triple bottom line. To some extent this is being offset by the rise in mineral prices, but this may or may not continue. The other serious issue facing all companies is the replacement of economic reserves as exploration levels over the past decade continued to decline in line with falling mineral prices. In order to underpin the sustainability of the mining industry it is necessary to continue to reduce cost, reduce the mine environmental footprint, whilst increasing community benefit. At the same time it is imperative that we increase the economic reserves. The highest risk is in adding new mineral discoveries as the strike rate for economic discovery decreases. Gekko Systems Pty Ltd recognises that the most simple and risk averse route to increasing economic reserves is to reduce cut-off grade in the mine, thereby bringing formerly uneconomic reserves into the economic category. We have been developing a new process flow sheet which embodies the triple bottom line and the issue of economic replacement of reserves. This paper describes this flow sheet and presents four examples where this concept is/can be applied to bring about triple bottom line benefits. Sustainability can only be assured if we are the ones in control of our environment, costs and reserves.

Jan 1, 2007

By R. G. Gürtunca, J. A. Breslin

This paper briefly describes the progress in mine safety in the United States, with emphasis on recent events that have followed since the explosion at the Sago Mine in January 2006. Legislation following the mine accidents last year and areas of work carried out by the National Institute for Occupational Safety and Health (NIOSH) related to the accidents are discussed. American coal production in 2006 was 1,150 million short tons. Most of this coal is consumed domestically, with annual exports of coal about 50 million tons. One third of annual production is produced at surface mines and the rest from underground. This coal is produced by about 82,000 miners working at 1,400 coal mines. Major improvements in coal mine safety have been made in the US since the Federal Mine Safety and Health Act of 1977. The fatal injury rate in underground coal mines between 1977 and 2004 was reduced by 47.8% to 0.036. The annual number of fatalities dropped from 112 to 14 during that period. Likewise, the non-fatal days-lost injury rate was reduced by 42.6% from 10.87 to 6.24. The improvements in mine safety during this period can be seen in the graph of underground coal mine explosion fatalities and injuries from 1980 to present, which is shown in Figure 1. Between 1984 and 1993 (9 year period) there were 5 explosions and one major mine fire, for a total of 55 fatalities. Over the seven year period from 1993 to 1999 there were no fatalities from coal mine fires and explosions. However, in the six years since 2000 there have been 5 explosions and one fire, which have caused 37 fatalities. [ ]

By Li Shibo, C. Halls

The compositions of olivine, pyroxene and chromite from the Proterozoic ultramafic complex are analagous to those of cumulate ultramafic rocks of tholeiitic origin, suggesting that the parent magma may have been tholeiitic rather than komatiitic. The complex contains economically significant Ni-Cu sulphide mineralisation. The high sulphide/silicate ratio is best explained in terms of the segregation of sulphides from a large volume of magma, of which all but the ultramafic cumulate fraction has since been eroded. Platinum-group minerals that have been identified include sperrylite, moncheite, native platinum, froodite, merenskyite, michenerite and Pd-rich pentlandite lamellae exsolved from pyrrhotite. They are characteristically found in close association with chalcopyrite, either along the contacts between hydrosilicate and sulphide grains or in cracks within pentlandite and chalcopyrite, which may also be intergrown with galena. Crystallisation from a Cu-rich residual magmatic liquid also enriched in Pt, Pd, As, Sb, Bi, Te, Zn and Pb is postulated.

Jan 12, 1993

By George B. Clark

The purpose of this investigation was to determine the feasibility of designing and testing the elements of a small charge blasting system which will eliminate, or reduce to acceptable levels, most of the undesirable features of current underground drill and blast systems, i.e., 1) air blast, 2) ground vibrations, 3) flying fragments, 4) overbreak and fracture of surrounding rock, and 5) the cyclic nature of drill and blast operations. The experimentation was conducted in tunnels in granite and the results indicate that the basic technical concepts of the project were achieved. The next step is to design, construct, and test a prototype machine.

Jan 1, 1976

THE slide-rule, as a quick and convenient instrument for performing approximate calculations, is steadily growing more and more into favour with the engineer, and results obtained by it are considered close enough to enable him to satisfactorily dealwith a considerable portion of his work. To the surveyor, however, whose ordinary computations must be as precise as his measurements, the present makes of rule are insufficient, except for a very narrow margin of the scales and for rough work. Few will carry the rule when they can clearly see that it is unreliable for general routine, and the careful surveyor is inclined to look askance at those who do use it, recognizing the temptation there undtmbtedly must be to push it into work that the log book should be called upon to treat. From the fact that a surveyor's duties take him on the surface in all weathers, and underground in many wet and uncomfortable places, where the manipulation of a book of mathematical tables becomes both awkward and patience-trying, an efficient slide-rule must offer the mbst transparent advantages. Again, a surveyor being specially trained to read divided scales quickly and accurately, the slide-rule must commend itself as an apt addition to his outfit.

Jan 1, 1912

By M. A. Trevits, I. R. Houlison, A. C. Smith, T. P. Mucho

Timely and rapid intervention to underground combustion events (fires, explosions, and spontaneous combustion) is the key to the successful control of the mine atmosphere and restoring of a coal mine to production. The focus of this paper is the utilization of a GAG 3A jet engine system to combat either large out-of-control fires or to render an entire mine inert when access to problem areas is difficult or impossible. This system is based upon a Soviet designed agricultural jet engine which consumes aviation fuel with oxygen (O2) from the intake air and exhausts combustion gases, primarily carbon dioxide (CO2) and water (H2O), along with the nitrogen (N2) from the air and small amounts of carbon monoxide (CO) and hydrogen (H2). The system is designed to approach stoichiometric combustion (ideally, pure burning that scavenges all the oxygen from the intake air). Therefore, these exhaust gases are almost entirely “inert gases”- i.e., gases which do not contribute to, and in fact, can suppress the combustion process due to the lack of oxygen. Other methods to inert mine areas have been used in the US and internationally, but these methods usually use low flow inertisation equipment or methods. Use of these low-flow inertisation equipment and methods has been successful in proactively rendering gob areas inert and has the ability to inert the entire mine workings. Due to the low flow rate, however, a substantial period of

By Jesse A. Pfeiffer

CPAR, the Construction Productivity Advancement Research Program, is a new initiative of the Corps of Engineers to enhance U.S. construction industry productivity through the development and application of joint-funded research. CPAR seeks to balance the requirements of both the private sector and the Corps of Engineers construction program, to identify research needs that are common to both parties in a partnership for conducting research, and to achieve practical real-world products which will enhance productivity in the construction industry. Increasing costs of doing business has had a major negative impact on much of the nation's industrial base, and research and development (R&D) is among the areas hardest hit. The Congressional Budget Office estimates that since 1984 inflation adjusted R&D outlays in private U.S. firms have risen at an average annual rate of three percent, or about half the rate of gain of the preceding decade. And, despite a significant increase in foreign competition, the portion of gross national product (GNP) devoted to R&D is lower today than 20 years ago. For the case of the U.S. construction industry, the numbers are even more dramatic.

Jan 1, 1989

By Randhir Sehgal

Heavy media processes have been used for cleaning +28 mesh coals for a number of years, Two applications, i.e., the vessels and the cyclones are widely used in the U. S. for this purpose. The basic reason for the popularity of these systems is their extremely high efficiencies for particle sizes above 28 mesh, However, application of heavy media technology to fine coals below 28 mesh, has been limited due to the following reasons: o Inability to make size separations effectively at sizes below 28 mesh o Necessity of feeding large quantitites of magnetite to the separators o Difficulty of recovering magnetite in the presence of large quantities of coal o High levels of coal contamination in the recovered media, leading to high circulating loads and ineffective control of media gravity

Jan 1, 1981

By N. L. Ayres

Tendon support systems have been successfully used to stabilize excavations. Tendon support systems are routinely designed using the axial load-bearing capacity of tendons, namely the tensile strength. To attain tensile strength the tendon must be loaded along its length, which often does not occur in practice. Tendons should optimally be installed at 90° to the surface of the excavation to achieve maximum penetration depth, yet this is often not physically or practically possible, and installations at angles less than 90° occur. Furthermore, the intersection of geological features within the rock mass frequently results in complex loading situations on tendons. The position and angle at which loading occurs results in different combinations of tensile and shear forces acting on the tendon, which can impact on the support performance of each unit and ultimately the whole system. All factors that influence the support system should be understood and taken into account to ensure a sound support design. Combination loading situations are further investigated and tested to obtain a better understanding of the mechanisms involved and the effects on tendon load-bearing capacity. Tendon support units were tested at different installation angles to establish the tendon performance, mechanical behaviour, and load capacity during these loading situations. The results and outcomes are aimed at providing rock engineers with additional data and improved understanding of how tendons could perform under certain conditions.

Jan 1, 2014

By Brian Hart, Stamen Dimov

"The Time of Flight Secondary Ion Mass Spectrometer (ToF-SIMS) is unique in that it measures the outermost atomic layers of any material. The technique is particularly suited for determining surface chemical composition of mineral particles. It is most commonly used as a diagnostic tool to measure mineral surface chemical variability in plant and bench top flotation separation processes. Recently, research towards understanding the full capability of the instrument has resulted in the development of new diagnostic applications related to various Au extraction technologies and the development of the ToF-SIMS as a predictive tool for assessing the chemical reactivity of the ore.In this paper we will present a brief review of the ToF-SIMS technique with recent advances in instrumentation and methodologies including:•,?recent developments and advances towards a semi-quantitative approach to the evaluation of mineral surface modifiers (ex. Cu),•,?flotation case studies investigating activator, depressant and collector loading variability within a flotation process,•,?the recently developed chemical reactivity test which we believe has the potential to predict the behaviour of minerals in a flotation test in response to chemical transfer during grinding,•,recent applications for determination of surface Au preg-robbed in carbonaceous materials.A portion of this material has been recently presented at the COM 2009 meeting and at SIMS XVII (see Dimov et al 2009 and Hart et al, 2009).INTRODUCTIONIn flotation seperation surface chemistry is the principal determinant for selective separation of the various mineral phases (Ralston, 1994, Smart et al, 2003). Determination of this hydrophobic/hydrophilic balance by particle therefore requires correct identification and selection of the particular mineral phase(s) followed by a statistical analysis of the surface chemical characteristics of the particles with an estimation of the spread of values (Smart et al, 2003)."

Jan 1, 2010

By B. A. Zaharov, J. M. Shneerson, L. V. Chugaev, M. T. Zhunusov, A. M. Markelov, S. V. Drozdov

The main direction of research was the application of autoclave technology for the flotation concentrates or biooxidation feedstocks. The industry modernization also expects the possibility of increasing the yield of the flotation concentrate, to allow an increase in gold extraction in flotation circuit. This paper provides brief description of results obtained for concentrates with the yield of 4 and 8%, as well as corresponding biooxidation feedstocks. Technological efficiency of autoclave oxidation is shown for both concentrates and biooxidation feedstocks. The process has been evaluated on a laboratory and a continuous pilot plant scale. Gold extractions from POX discharge are ranging from 94-97% for each product, with only 5-7 kg/t cyanide consumed.

Jan 1, 2014

By Mario Samamé Boggio

El presente texto describe algunos aspectos de la inversión extranjera en tres períodos: fines del siglo XIX, la primera mitad del siglo XX y segunda mitad del siglo XX. Dentro de lo quince casos analizados se halló que 5 empresas son iguales: Northern, Southem, Santander, Santa Luisa y Madrigal; 4 empresas se han "peruanizado" total o parcialmente: Caylloma, Ticapampa (Alianza), Lampa (Minsur) y Ruaron, 3 empresas se han agotado aparentemente: Santo Domingo, Salinas y Minas Ragra, 1 yacimiento revertió al Estado y fue desarrollado por Minero Perú: Cerro Verde; y 2 empresas fueron expropiadas y estatizadas: Cerro de Pasco Corporation y Marcona. En todos los casos no hubo descubrimiento del yacimiento por el inversionista, quien compró las concesiones y denuncios, con excepción de Marcona que estuvo explorado y desarrollado y fue contratado para su explotación.

Mar 1, 1982

By Stanley R. Riggs

Onslow Bay is a broad, shallow, high-energy shelf system bounded by the Cape Lookout and Frying Pan shoals. It is generally a sediment-starved shelf system dominated by hardbottoms with a scattered and discontinuous veneer of mobile Holocene sediments. Phosphate-rich beds of the Miocene Pungo River Formation crop out in a belt 150 km long and up to 50 km wide across the continental shelf in Onslow Bay, North Carolina. Previous research has demonstrated that a few of these beds contain vast quantities of potentially economic phosphate resources that occur in the surface and shallow subsurface sediments. Onslow Bay contains five phosphate-bearing beds predicted to include up to 20.7 billion tons of in-place phosphate concentrate with total sediment grades ranging up to 22.9% P2O5 and adjusted average concentrate grades of 29.8% P2O5. These phosphates are lithologically and chemically similar to phosphates currently being mined in the nearby Aurora phosphate district in North Carolina. Various lithologies of the Pungo River Formation and associated rock units of Oligocene and Quaternary age crop out on the sea floor to form extensive hardbottom habitats that dominate almost 100% of Onslow Bay. A large proportion of these hardbottoms appear to be sea floor deserts, whereas others are virtual oases with rich associations of benthic organisms. These important differences in benthic community structure appear to be greatly influenced by one or more of the following variables: 1) geologic framework (geologic formation, hardbottom composition, morphology, and spatial orientation relative to dominant currents and waves), 2) texture, movement, and accumulation of surface sediments, and 3) flow rates and chemical composition of discharged submarine groundwater.

Jan 1, 1992

By Takuya Taguchi, Toshihiro Ogata, Atsuio Inoue, Shigeyuki Sasaki

Highly improved drilling machines and mucking machines have been used for the underground construction. To have rapid construction, the roles of blasting operation ha ve been growing more important. At the most tunneling of present, cartridged emulsion explosives have been used for a blasting in Japan. Under this circumstance, a blasting system of ANFO explosives using loading machine has been used recently for a tunnel blasting. However, ANFO has some problems, such as a useless explosives in wet boreholes, bad blasting fumes and the ammonia gas due to the decomposition of ammonium nitrate in contact with the sprayed concrete in tunnel.

Jan 1, 2005

By Marco D. Boscardin

Control and mitigation of building response to construction activities are assuming a greater role in design decisions for underground construction. Alternatives for controlling building response have multiplied with the continued development of ground modification methods, better control of construction activities that cause ground movements, and increased understanding of building behavior and response. This paper describes approaches to estimating building response to construction-related ground displacements caused by adjacent excavation and highlights the discussion with several case history examples. Examples discussed includes experiences with two, seven-story historic structures, supported by timber piles with granite block pile caps, which were underpinned in preparation for ground-freezing ground stabilization and tunnel construction beneath the buildings. The elevation of each building column was monitored and elevation adjustments were actively performed during construction. The second example examines the performance of a slurry wall braced cut, 45 to 50 feet deep penetrating through a stiff crust into a soft clay layer and associated building response. This cut was immediately adjacent to two, approximately 15-story office buildings, which were supported by deep foundations founded in the stiff crust.

Jan 1, 2003

By R. P. Maloney

The Bureau of Mines conducted a reconnaissance of the less accessible parts of the Beluga River coalfield in August 1957 to determine, if possible, which areas were most favorable for developing large reserves of coal suitable for open-pit mining. Several outcrops of subbituminous coal were observed within an area about 30 miles long and 3 miles wide; neither the length nor the width of the coal-bearing area was delineated by the examination. Coal beds 30 feet thick or more outcrop at two places, and beds 5 to 20 feet thick or more outcrop fairly abundantly along the Beluga River and its tributaries The coal measures appear to occur in a series of folds. The overburden comprises glacial gravels and poorly cemented sandstones and ranges from 20 to 400 feet in depth. Few partings were seen in any of the coal beds. Samples ranged in calorific value from 6,240 to 8,246 B. t. u. on an as-received basis. Adequate water is available for stripping by hydraulic methods.

Jan 1, 1958

By David Siu

Many problems were encountered with the mechanical wedge-type splices used for the 15-inch square precast prestressed concrete piles installed at an industrial plant site. Many of the wedges were breaking during installation of the splices and after pile driving resumed following splicing. Dynamic monitoring of the piles and uplift loading tests confirmed that the problems were associated with cracked or damaged wedges. More ductile, annealed wedges were subsequently used, and, while not completely satisfactory, they were found to perform better than the original more brittle wedges. Introduction Long precast prestressed concrete piles were installed to support heavy, settlement-sensitive structures at an industrial plant in Port Alberni, British Columbia, Canada. The piles were driven through soft compressible silts and clays to toe bearing in a dense sand and gravel deposit or on bedrock. Each pile consisted of two or three segments joined with mechanical wedge-type splices trademarked DYN-A-SPLICE. Shortly after construction began, problems arose during pile installation, and these problems were, later, identified to be related to the wedges, or clamps, used to connect the splice plates.

Jan 1, 1991