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By Terry S. Cory

This report describes the results of a measurement program to determine the broad spectral characteristics of both differential and common mode noise on phone lines in three coal mines; and, signal attenuation spectral characteristics on the same broad basis over phone line strings with taps/branches. The frequency range used was baseband -1000 Hz for resolution bandwidth ranging from 100 Hz near baseband to 30 KHz near I MHz. The signal attenuation measurements were performed on all three "legs" of taps where possible and applicable. Results were obtained comparing shielded and unshielded phone lines In one mine. The results include an improved electromagnetic noise chart for coal mines showing variations with types of mines, topology, and location of noise sources; also, fundamental high-frequency limit on untreated phone lines in coal mines is identified

Jan 1, 1981

By X Zhang, Y Zhu, P E. Ngoepe, P P. Mkhonto, W Xiong, L Han, L Lu

The triazine molecules have not been given much attention and they are potential collectors that may positively impact the mineral processing industry. The adsorption of triazine as collectors such as sodium 2,6-dithio-4-butylamino-1,3,5-triazine (SDTBAT) on pyrite form a basis in design of flotation collectors that may be applicable in a wide range of sulfide minerals. The SDTBAT collector was compared with the sodium normal butyl xanthate (SNBX) and sodium normal butyl dithiocarbamate (SNBDTC). All collectors were adsorbed in their neutral form containing sodium on the pyrite (100) surface. The computational calculations found that the adsorption energies followed the order: SDTBAT (-300.35 kJ/mol) > SNBX (-186.10 kJ/mol) > SNBDTC (-163.78 kJ/mol). It was observed that the SNBX and SNBDTC adsorbed through the S atoms, while the SDTBAT adsorbed through the S atoms and N atoms onto Fe atoms. It is clear that the SDTBAT had a strong binding energy which is attributed to the presence of the triazine group that is electron depositing to the active S atoms compared to the SNBX which possessed the oxygen that is electron withdrawing. Moreover, the SDTBAT collector was found to bind stronger than the xanthate. This was complimented by microflotation tests that showed fast floating and higher recoveries of pyrite when using the SDTBAT collector than the xanthate and DTC. This clearly demonstrated that the SDTBAT is a potential collector to replace the xanthate collector due to its high selectivity and flotation power.

Aug 24, 2022

By A D. Stewart Gillies

Resource rent taxes are taxes which only become effective at such a time as a pre-determined rate of return has been achieved by an operation. Resource Rent Taxes have from time to time been considered for implementation in bothAustralia and New Zealand. The offshore petroleum industry in Australia is already subject to RRT as is the Roxby Downs (Olympic Dam) Mine in South Australia. Both the mining and petroleum taxation regimes in Papua New Guinea include a resource rent tax component called Additional Profits Tax.   The implications of the current form of additional profits tax for shareholder cash returns are that the tax burden on the operation may suddenly increase at some stage in the life of the mine if and when the threshold level of profitability for the tax to be triggered is exceeded. From that point in time onwards the cash return to the shareholders on the capital invested is greatly diminished. For mining companies in Papua New Guinea, the effective tax rate increases from 35% to 57.75% as a result of the onset of additional profits tax. This tax rate penalty is so severe that there appears to be merit in considering the concept of managing profitability through time rather than purely maximising annual pre-tax profits as is currently the case in most mining operations. This would have the benefit of deferring or perhaps preventing altogether the onset of the tax. One possible method for the effective management of profitability is through the control of average mining grade by cutoff grade manipulation.   Traditional cutoff grade theory has usually considered taxation as a direct cost at a fixed or variable percentage of annual profits. As a result of this most analyses are conducted on a pre-tax basis. If tax is included in analyses it is usually present as a time independent function of gross profit. Additional profits tax is both time, and rate of return dependent and therefore not adequately accommodated by currently accepted cutoff grade theory.   A review has been made of the effects of resource rent taxes on both the investment decision-making process as well as possible development and mining strategies which may be employed by mining companies faced with resource rent taxes. The review includes examples based on the structure of additional profits tax which is levied in Papua New Guinea.

Jan 1, 1995

By E. D. Palmes

Phase I of these studies demonstrated the feasibility of measuring the efficiency and capacity of sorbents in tube-type samplers for contaminant gases. This was accomplished by measuring concentration at various points along the length of the diffusion path during sampling. Concentrations were measured by removing small aliquots with gas-tight syringes and gas chromatography. With hexane as the gas and activated charcoal as the sorbent the procedure was quite successful and we proceeded with Phase II of the study; this involved application of the principle to gases of importance in diesel exhaust using a variety of sorbents. When we worked with high concentrations of the test gas we clearly demonstrated the differences in both efficiency and capacity of the sorbents for each of several gases. The chief drawbacks of the system were that we were unsuccessful in determining more toxic gases at realistic occupational exposure levels or determining formaldehyde at any level using the flame ionization detector. It was concluded that, although the method is feasible, more sensitive methods of measuring concentrations of gas in the tube must be developed to make the procedure applicable to regions of chief industrial hygiene interest.

Jan 1, 1983

By W. E. Stephens, A. J. Boyce, D. Lowry

Paper presented at Mineralisation in the Caledonides, the Mike Gallagher memorial meeting held in Edinburgh, 27-28 June 1996. An integration of S isotopic, fluid and mineralogical data for granitoid-related mineralisation showed that the porphyry systems had a predominantly subcrustal magma source, but the inner magma pulse of two-mica granite in the Fleet pluton was derived mainly from reduced sediments. The porphyry-style mineralisation formed from boiling fluids at high crustal levels, with a moderately saline fluid percolating down to the upper veins as they cooled but not penetrating the deeper Talnotry deposit. Veins in peripheral greywackes have a significant magmatic component but also incorporated CO2-rich components and metals released by dewatering of host sediments in response to granitoid intrusion. The low grade of regional metamorphism resulted in the significant fluid input from country rocks which led to the more exotic mineral compositions, especially where argillaceous sediments were involved

Jun 19, 1905

By James M. Franklin

Research on modern hydrothermal systems provides quantitative measures of the processes of formation of hydrothermal fluids and of precipitation mechanisms from them. Studies of ancient deposits provide new information regarding volcanological processes that are related to the deposits, as well as data on their spatial and temporal compositional variations. Mew exploration guidelines result from both aspects of research. The most fundamental requirement for large metalliferous hydrothermal systems is an abundant heat supply for the upper two kilometers of the crust. This heat may come from a focused heal source (shallow-level subvolcanic intrusion), but ambient heat also may have provided enough energy for the reactions necessary to effect leaching of metals, especially where heat flow is particularly high (i.e. very large or high-temperature magmatic source, such as ultramafic environments). For most VMS systems, the majority of the metals were derived through leaching from footwall strata; in addition interstratal fluids may enter subvolcanic intrusions during episodes of magma a chamber "cracking," engendering some '?magmatic" component in the hydrothermal system. Direct contributions of metalliferous magmatic fluid also may be significant from arc-related or back-arc felsic or alkalis systems. These latter contributions may form exceptionally high - grade portions in some deposits. Subvolcanic intrusions, which are excellent indicators of high heat flow and may have been the direct driving mechanisms for some stems undergo two stages of alteration: On intrusion emplacernent. fluids may rapidly enter and react with their mesostatic portions, evident in the sills in the Middle Valley. High temperature interactions caused albitization and destruction of oxides and sulfides, releasing metals. During terminal hydrothermal stages, the metalliferous fluid collapsed into the intrusions, forming disseminated and vein sulfides.

Jan 1, 1998

By Susan P. Taite, Alain R. Charest, Peter D. Lewis

The El Sauzal deposit is a classic, high sulfidation, epithermal gold system located in the southwestern Chihuahua state of Mexico (Fig. 1). A Francisco Gold geologist discovered the prospect in1995. El Sauzal was encountered as a result of an extensive grassroots exploration program in the rugged, dissected volcanic terrains of the Sierra Madre Occidental, around the historical Batopilas silver camp. At El Sauzal, high grade gold is hosted within a series of more permeable, low-dipping, lithic and fine-grained dacitic rocks of early Tertiaryage. The mineralization appears tobe structurally and lithologically controlled. The alteration characteristics are typical of a high sulfidation system, including kaolinite, illite, alunite, dickite and pyrophyllite.

Jan 1, 2005

By Wang Shulan

The synthesis process of BaTiO3 from TiO2 and BaCO3 in the molten NaOH-KOH at 350oC was studied by the A.C impedance technique. The A.C. impedance of molten NaOH-KOH (xNaOH = 0.36) and the variation of the conductivity of the salt with time during the synthesized process were measured. The synthesized reaction of the BaTiO3 and the decomposition reaction of BaCO3 are fast and were finished in 10min. The interaction between TiO2, BaO and BaTiO3 and the molten salt was confirmed by the variation of the conductivity.

Jan 1, 2005

By M. Soleymani Shishvan

"Continuous mining systems containing multiple excavators producing multiple products of raw materials are highly complex, exhibiting strong interdependency between constituents. Furthermore, random variables govern the system, which causes uncertainty in the supply of raw materials: uncertainty in knowledge about the reserve, the quantity demanded by the customers, and the breakdown of equipment. This paper presents a stochastic-based mine process simulator capturing different sources of uncertainties. It aims to quantify the effect of geological uncertainty and its impacts on the ability to deliver contractually defined quantities and qualities of coal, and on the system efficiency in terms of utilization of major equipment. Two different areas of research are combined: geostatistical simulation for capturing geological uncertainty, and stochastic process simulation to predict the performance and reliability of a large continuous mining system.The process of modelling and simulation in this specific production environment is discussed in detail. Problem specification and a new integrated simulation approach are presented. A case study in a large coal mine is used to demonstrate the impacts and evaluate the results in terms of reaching optimal production control decisions to increase average equipment utilization and control coal quality and quantity. The new approach is expected to lead to more robust decisions, improved efficiencies, and better coal quality management.IntroductionContinuous coal mining systems containing multiple excavators producing multiple products of raw materials are highly complex and exhibit strong interdependencies between constituents. A network of conveyor belts is used for transportation of the extracted materials to different waste dumps or the coal stockpile.Optimal decision-making in short-term planning and production control are impacted mainly by geological uncertainty associated with incomplete knowledge of the coal deposit represented in the reserve block model. These uncertainties cause deviations from expected process performance. For more robust decision-making, understanding the impacts of these stochastic elements plays a key role."

Jan 1, 2016

By H. H. Schrenk, Carlton E. Brown

"The purpose of this paper are (1) to present a broad picture of the recognized methods of measuring the various forms of atmospheric pollution; (2) to evaluate the significance of such measurements; and (3) to suggest suitable methods for obtaining comparative information on the concentration of contaminants in city air.The atmosphere (the gaseous envelope surrounding the earth) consists of a mixture of gases. These gases and their usual proportions are:4/The volume of water vapor in the atmosphere ranges from almost zero (in very cold weather) to about 5 percent arid averages about 1.2 percent.Strictly speaking, any other substance in the atmosphere or an excess of any of the substances mentioned (with the possible exception of water) is a contaminant. Needless to say, there are many contaminants in the atmosphere.In accordance with their physical state, contaminants may be classified as gaseous or particulate, and the latter may be classified as solid or liquid matter. Particulate matter, especially when dispersed in some medium such as air or some other gas, sometimes is referred to as dispersoid, and the complete system of gas and dispersoid is referred to as aerosol.All substances on the earth are potential sources of atmospheric contaminants. Combustible materials (particularly fuel for heating and power), sea water, earth or soil, metals, and animals (including man) are some of the important sources of contaminants.Ordinarily gases are produced by chemical processes, whereas dispersoids are produced by both chemical and physical processes. There are two general dispersoid-producing processes: (1) Condensation, in which molecules join to form larger units or particles, and (2) disintegration, in which large units are reduced to the particulate range (which for the purpose of this article may be considered to be from 100 microns, or 1/254 inch, down to molecular size) by such processes as crushing, grinding, abrading, and atomizing.“Condensoid"" is a convenient term for dispersoids formed by condensation, and ""disintegrasoid"" for those formed by disintegration. Solid condensoids are sometimes called ""fume,"" solid disintegrasoids ""dust,"" liquid condensoids ""fog,"" and liquid disintegrasoids ""mist.""5/"

May 1, 1942

By J. R. Thoenen

In the summer of 1937 the authors began a series of time studies of the various processes employed in' the production of crushed stone. These studies, made at quarries situated in the eastern and southeastern parts of the United States, have not been completed, but to make results available to the industry as early as possible, it was decided to publish summaries of the studies made to January 1, 1939, as a series of progress reports. The first of these dealt with power-shovel loading and was issued as Report of Investigations 3461 in September 1939. The second, issued in September 1939 as Report of Investigations 3467, dealt with quarry haulage. The present report discusses analyses of time studies of primary drilling at the same group of quarries. OBJECT Or STUDY Pressure of business problems frequently requires the entire attention of quarry management, and in consequence internal plant economies often are neglected. Also, operating officials absorbed in their local problems are prone to overlook possible economies that would attract attention immediately were they critically examining another plant. The authors felt that technical studies at a number of plants, made by impartial engineers, might disclose opportunities to reduce costs or improve efficiency in internal plant processes.

Jan 1, 1940

By W. M. Myers

Jet is a substance of organic origin and has been defined by the U. S. Geological Survey as a "dense black lignite, taking a good polish, and sometimes used for jewelry". Jet is characterized by the lustrous, intense black surface it displays when polished. It is due to this property that the expression "jet black" is so commonly used to imply intense blackness.

Jan 1, 1923

By David Gatto, Nicolas A. Willig-Friedrich, Jeff A. Segar

"With the increasing demand for electricity, and requirements to generate this power cleanly, more producers are turning towards hydroelectric power. A project in Iowa currently under construction will retrofit an existing Army Corps of Engineers Dam with a hydroelectric generating facility. The design of the intake structure requires the construction of a diaphragm retaining wall. The T-shaped diaphragm wall elements retain an unbalanced fill height up to 21.3 meters (70 feet). The design required a single production element be constructed, tested, and instrumented prior to beginning construction of the rest of the elements. The testing included extensive concrete mix design development, coring, and Cross Hole Sonic Logging. Installed in the other production elements are 10 inclinometers, 4 pressure cells, 4 piezometers, and multiple survey monuments. Some of these instruments require manual readings while most are monitored by an automatic data acquisition system and instantly transferred to a website providing real-time graphical display of the data. This paper will discuss the construction of the diaphragm wall from the contractor’s perspective when working on a site only large enough for two service cranes and a Hydromill excavation unit, without any storage area on the construction pad, describe the testing performed and the quality control procedures employed, and investigate the information gained from the automated instruments providing real time measurement readings.INTRODUCTIONIn 1964 the US Army Corps of Engineers (USACE) constructed a dam by raising the surface grade approximately 34.7 meters (114 feet) above the natural ground line using a combination of fill types. This earthen dam stretched slightly longer than a mile intersecting the flow of the existing Des Moines River. The center of the dam is a concrete spillway consisting of 12 monolith sections. On each end, three of the sections extend 42.6 meters (140 feet) from the spillway to transition from the concrete dam sections to the earthen dam section. Adjacent to these three sections on the East end is where the contractor is actively working, for a private developer under a lease agreement with USACE, on this site to convert it to a Hydroelectric facility licensed for an output of 36.4 megawatts, enough power to meet the needs of about 18,000 homes. To create this, a powerhouse structure, housing two vertical Kaplan turbines is being added to the downstream side of the existing dam. From the power house, two penstock pipes will be cored through the existing concrete monolith sections and connect to the Intake structure on the upstream side of the dam. Protecting and reinforcing the dam adjacent to the intake structure is a new diaphragm wall. This wall is constructed using T-shaped diaphragm elements, acting as a cantilever retaining wall for the intake platform. Figure 1 shows a diagram of the upstream features of the construction."

Jan 1, 2016

By R Munoz, R González, J Vallejos, A Delonca

In panel caving in underground mines, it is essential to characterise and monitor the stress and stability state of production level pillars to ensure the extraction of the mineralised ore column and the safety of workers. Pilar Norte is a sector in the El Teniente mine that forms a pillar between the undercut fronts of the adjacent Esmeralda and Reservas Norte sectors. It exists in a high-stress environment, which may induce damage to the rock mass production pillars. Generally, numerical models are calibrated using observed damage in galleries. This procedure does not discriminate between the structural condition and/or the blasting damage effects. This paper proposes a technique that uses borehole cameras to measure stress-induced damage. This has the advantage of being at the intact rock scale, meaning that the effect of geological structures is negligible and the blasting damage factor is eliminated. Comprehensive geotechnical characterisation and tomography monitoring has been undertaken at Pilar Norte to describe and determine the rock mass behaviour of the production pillars. By combining analytical, empirical and numerical models, a correlation between the measured overbreak recorded by the borehole cameras and the stress level of the pillar was developed. The methodology can be routinely applied to estimate the stress state in the production pillars.CITATION:González, R, Munoz, R, Vallejos, J and Delonca, A, 2016. Characterisation and monitoring of the stress state of production pillars at El Teniente Mine, in Proceedings Seventh International Conference and Exhibition on Mass Mining (MassMin 2016), pp 197–202 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2016

By F. D. DeVaney

Manganese-bearing deposits f the Leadville, Colo., district are of two distinct types. Manganosiderite, a combined or intimately mixed ferrous and manganous carbonate, occurs in unaltered zones as the predominant mineral. From 50 feet below the surface to as deep as 900 feet, psilomelane and wad, both black manganese oxide minerals, are found in intimate contact with hematite and limonite. A typical analysis of the black oxide ore shows 20.08 percent Fe, 18.64 percent Mn, 15.91 percent insoluble, 14.91 percent moisture, 0.94 percent Zn, and 2.13 percent Pb. A considerable tonnage of the oxide ore has been mined for production of spiegeleisen and for other purposes.

Jan 1, 1940

By F. D. DeVaney

Manganese-bearing deposits of the Leadville, Colo. district are of two distinct types. Mangano siderite, a combined or intimately mixed ferrous and manganous carbonate, occurs in unaltered zones as the predominant mineral. From 50 feet below the surface to as deep as 800 feet, psilomelane and wad, both black manganese oxide minerals, are found in intimate contact with hematite and limonite. A typical analysis of the black oxide ore shows 20.08 percent Fe, 19.64 percent Mn, 15.91 percent insoluble, 14.91 percent moisture, 0.94 percent Zn, and 2.13 percent Pb. A considerable tonnage of the oxide ore has been mined for production of spiegeleisen and for other purposes.

Jan 1, 1940

By Gustavo Elói de Sá Lima

A estratégia de manutenção de locomotivas da VLI sofreu significativa modificação após a implementação de propostas de consultores americanos, baseadas principalmente, na execução de atividades fora de oficina, realizadas em estruturas chamadas de “Track Service”, estruturas as quais contam basicamente com uma vala para inspeção na parte inferior das locomotivas. Dessa forma, foi possível capturar diversos ganhos em custeio e redução de investimentos, como por exemplo o aumento de periodicidade entre manutenções preventivas e redução do projeto da nova oficina de Paulínia.

Oct 30, 2017

By J. Sottile, J. L. Kohler

Component failures in the electrical control circuits of mining machines account for a large percentage of the total downtime of the machine. Once a failure has occurred it is always a tedious and usually a time-consuming task to locate the failed component. Moreover, the pressure to quickly locate the cause of a delay can lead to compromises in safety. Thus an onboard diagnostic system, essential for an automated machine, would be a very useful addition to existing machines. This report details U.S. Bureau of Mines development of a generic procedure for synthesizing diagnostic systems for electrical-control-circuit failures in mining machinery. A continuous mining machine is used as the testbed to illustrate the application of the developed methodology. Substantive differences among mining machine control circuits made it impossible to achieve a generic diagnostic system, but a generic approach for the synthesis of the diagnostic system was possible. As the research progressed, it became apparent that an algorithmic approach was better than an expert- system-based implementation. A prototype system was constructed and used to evaluate the diagnostic system. Prototype implementation issues are also examined.

Jan 1, 1993

By Tristan H. Jones

Beginning in 1987, miniature dataloggers approved by the Mine Safety and Health Administration (MSHA) were publicly available for sale. The principal among these was the model CR21XQM, manufactured by Campbell Scientific, Inc. These dataloggers had been tested and were deemed permissible by MSHA and thus could be installed in the return air of an underground coal mine. In 1996, production of all permissible Campbell Scientific dataloggers ceased due to lack of sales. Data collection with these dataloggers has been a staple of ground control research in the United States for decades, and, without them, or a replacement, the capability to monitor ground behavior is severely impacted. Since that time, any party requiring a permissible datalogger has needed to borrow one that was purchased during the production years. In order to fill this technology gap and ensure its own data-gathering capabilities, the National Institute for Occupational Safety and Health (NIOSH) has developed and refined its own miniature data acquisition system (MIDAS). On February 16, 2010, MSHA deemed the MIDAS to be permissible and approved it for use in the return air of an underground coal mine. The MIDAS is an intrinsically safe, 16- or 24-bit datalogger, compatible with a wide range of resistive, single-ended, and differential-type instrumentation. It contains enough data storage memory to operate for over a year with typical data rates and is efficient enough to do this on a single C-sized alkaline battery for that entire period. It is menu-driven and requires no programming knowledge to operate. It supports wireless or hardwired communication for datalogger setup and data download. This paper describes the design, field and laboratory testing, and capabilities of the MIDAS datalogger. While not as fully -functioned as the CR21XQM, it is the only new permissible datalogger available, and there is intent to make it available to the mining industry for purchase.

Jan 1, 2012

By Yue-yuan Li

China has abundant magnesite resource, but the low-grade and powder ores have always been rejected, which influences the comprehensive utilization of resource and often causes circumstance problems. The present work investigated the preparation of magnesia whisker using magnesite tailings as starting materials by preparation magnesium carbonate whisker as precursor firstly in the route of calcination, hydration, carbonation and pyrolysis, follows by second calcination of the precursor. The influence of pyrolysis conditions and additives on morphology of magnesium carbonate crystal as well as the influence of calcination conditions on morphology of magnesia whisker was investigated. The results showed that thermal decomposition products was MgCO3?3H2O. Magnesium carbonate whisker with length of 10~60 µm and the length-to-diameter ratio of 10~20 was prepared when soluble magnesium salt was added. While temperature was elevated at 1°C?min-1, magnesia whisker with length of 10~60µm was obtained.

Jan 1, 2010