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By R. H. Grau

Improving the air quality in metal/nonmetal mines is important in protecting the health of miners. Air quality can be improved in metal/nonmetal mines by developing proper ventilation techniques. Mine ventilation systems require stoppings to direct the airflow and establish pressure differentials throughout the mine. Due to their large size, stoppings in large-opening mines are cumbersome and costly to construct and maintain. As part of its mining health and safety program, the National Institute for Occupational Safety and Health (NIOSH) designed and tested two novel stoppings (Super Stopping and the EZ-Up Curtain Stopping) at its Lake Lynn Laboratory (LLL). The Super Stopping is designed as a long-term permanent stopping for use in the main entries of the mine, while the EZ-Up Curtain Stopping, although very durable, is designed more for portability and ease of installation. This paper describes the design, materials, and construction methods used for these stoppings as well as their performance and durability when subjected to tests simulating actual production face blast pressures.

Jan 1, 2006

By Robert C. Speck

The U.S. coal industry has long utilized the pillar-extraction mining technique as a method for maximizing coal recovery. Like longwall mining, it causes large-scale movements that progressively propagate from mine-level to the ground surface and may affect the groundwater regime, surface drainage and surface structures. The U.S. Department of Energy, in an effort to foster in- creased use of total extraction mining techniques, has recognized the need for a better understanding of these movements that will lead to a greater compatibility between coal mining and present and future land use. As part of that goal, GAI Consultants, Inc. is currently in- stalling instrumentation to monitor the ground movements associated with pillar extraction mining at Kitt Energy Corporation's No. 1 mine in northern West Virginia.

Jan 1, 1982

By H. C. Roland Kammel

Stannous sulfate electrolytes are widely used nowadays in electrolytic tin production. Characteristic features of this electrolysis process are that dense cathode deposits can only be obtained by additions of organic additives and that so called ?black mud is formed on the anode surface which leads to an increase in cell-voltage. In order to prevent excessive cell-voltages or oxygen evolution the black mud has to be removed periodically. Studies in laboratory scale have been performed about the effect of different organic additives on electrolytic tin deposition and the formation of surface layers on pure and industrial tin anodes. Results reveal that organic addition agents are effective in reducing cathode roughening as well as extending the covering time of the anode ?by black muds.

Jan 1, 1985

By George R. McCormick

Because several new and unusual synthetic minerals were found in the system MgO-MgF₂ - SiO2 with Li * , or Nat a similar system with Geo₂ replacing Sio , plus Lit was investigated . In addition to the expected compounds of germanium , Ge - fluor - hectorite and a Ge - fluor- chrysotile were synthesized . Protoamphibole was not observed . Data are given for 69 compositions prepared in the system MgO- MgF₂ - Ge02 at 6.94 percent LiF .

Jan 1, 1964

By P. J. Watson

The objective of this study was to prioritize the potential risks nuisance and biologically active dusts and fumes present in metal and nonmetal mines. This was accomplished by ranking numerical values derived from a matrix formula calculation that took into account dose, mine population, and sampling size. Data used in these calculations were obtained from the Mine Inspection Data Analysis System (MIDAS). The dusts determined to have the highest risk potential were quartz respirable particulates, mine dust, cristobalite respirable particulates, welding fume components, and nuisance respirable dust. Other dusts and fumes that were not ranked in this study, due to small sampling population, but which show a potential risk, include asbestos, talc, hydrogen cyanide, organic compound dusts, arsenic, metal dusts, and metal and nonmetal fumes.

Jan 1, 1987

By R Castedo, L. M. Lopez, J. A. Sanchidrian

In 2014 the authors presented results from 13 tests made with two blasting seismographs on a vibration exciter. They measured coupling transmissibility as function of frequency (i.e. ratio of the velocity of the sensor mount to the velocity of the ground motion) from 16 to 200 Hz at one or two vibrations levels (5 mm/s or 0.2 in/s, and 20 mm/s or 0.79 in/s) with mounts freely placed, sandbagged, and anchored to a granite slab firmly attached to the plate of a vibration exciter. As the memory capacity of one of the seismographs prevented to cover low frequencies, e.g. 4-16 Hz, a new measuring campaign has been recently made to extend the study down to 2 Hz. In this campaign, two more techniques, in which the sensor mounts were fixed with thermal adhesive or a combination of duct tape and gypsum plaster, have been also investigated from 2 to 200 Hz at 5 and 20 mm/s. Free and sandbagged mounts lead to a weak coupling of the mounts to rock, so that transmissibility depends on the characteristics of the imposed rock motion (peak velocity and frequency). Measurements are accurate only at low frequencies (below 17 Hz for free mounts and 10 Hz for sandbagged) in the tested conditions (velocities up to 20 mm/s). Above these frequencies, ground motion in the measurement can be modified by a factor of 0.16 to 1.22. Anchored, glued and plastered mounts achieve a stiff rock-to-ground coupling, ensuring consistent measurements for the frequencies commonly found in blasting independently of the vibration level and the mount characteristics

Jan 1, 2015

By F. W. Gray

A GEOLOGICAL study seeking to determine, for economic purposes, the value of the Sydney coalfield as a source of coal supply. Limitations of the coalfield come under two main heads: (a) Areal extent of the undersea coalfield. (b) The distance from shore at which coal can be mined at a cost of production permitting its profitable sale. Conclusions reached are that the areal extent of seams below the Phalen seam is of. small economic importance, and that non-persistence of these seams in full thickness and quality in the undersea extension of the coalfield will put an end to profitable mining before any limitations connected with distance from the shore-line become operative. With respect to the Phalen seam, non-persistence or deterioration of the seam will become effective in the western part of the coalfield, and less certainly in the eastern part of the coalfield, before operation of limitations by distance from shore. In the central portion of the coalfield, the seam probably persists in commercially workable thickness and quality to beyond the limit of mining set by distance from the shore-line. With respect to the seams above the Phalen seam between the Mountain fault on the extreme western boundary of the coalfield and the assumed termination of the deposition area on the eastern extremity of the field near South Head of Morien, there appear to be only such limitations as arise from engineering approach, distance from shore, sufficiency of strata cover between the sea-floor and the upper coal seams, and quality of the coal (with certain reservations as to the continuity of the upper seams under Sydney harbour and in the Sydney Mines-Little Bras d'Or district). Some of these seams have fragmentary land outcroppings from which their persistence seaward is assumed, and there may be other and still higher seams in the strata column which are entirely submarine.

Jan 1, 1941

By D. M. Schubert

As a clean and renewable energy carrier, hydrogen is an important component of most alternative energy portfolios. Hydrogen combines very high energy content by weight with excellent environmental attributes. Since hydrogen reacts with oxygen to produce only water with release of energy, it can be used to power fuel cells, combustion engines, and turbines, without production of greenhouse gases at point of use. However, because of its low volumetric density, storing pure hydrogen is impractical. Thus implementation of hydrogen technologies requires materials that can safely store and release large amounts of hydrogen (1,2). In recent years, the U.S. Department of Energy (DOE) and other governmental agencies around the world sponsored extensive research on hydrogen storage materials, including those based on boron. These efforts have resulted in significant advances in hydrogen storage technologies. Boron materials stand out as leading candidates for hydrogen storage among the many options investigated. Combining excellent hydrogen densities, release rates, and safety characteristics, some boron materials can hold substantially more hydrogen by weight and volume than even pure liquid hydrogen (3-5).

Jan 1, 2010

By C. Vipulanandan, M. Dawood, Dongmei Pan

"With the aging infrastructure, there is a need to maintain and extend the service life of steel structures in general and steel piles in particular. Steel piles support not only vertical loads but also dynamic horizontal loads in onshore and offshore applications. In order to select the appropriate methods to repair corroded steel piles used in onshore and offshore application, corrosion mechanisms were investigated with the rate of corrosion in various environments. The corrosion rate of steel in soil, water and soil-water interface varied from 2 to 500 µm/year. Based on literature review and analyses, the repair methods can be broadly characterized as protective coating, electro-chemical methods, wrapping and encasement and partial replacement of steel. Also, methods to evaluate the repair materials and the repair configuration have been documented.IntroductionOne of the biggest challenges facing the aging infrastructure is the materials loss and deterioration due to corrosion. Many studies indicate that in the US alone, costs due to corrosion loss is more than $276 billion annually (Michiel et al., 2010). Corrosion is the major cause of deterioration of steel structures and components (MNC, 2005). Load bearing steel piles are used as foundations for various types of structures and hence corrosion is very much influenced by the environment such as soil, water and soil-water interface. Corrosion of steel pile foundations may result in reduced capacity in the axial and lateral directions. Hence, understanding the rate of pile corrosion is essential to select the appropriate repair methods to avoid excessive deflection and failure (Decker et al. 2008).To prevent the deterioration mechanisms that attack a pile, it is fundamental both to identify and understand the deterioration mechanism that has been the cause of damage. Understanding the deterioration mechanism allows the engineer to design a repair that will combat this type of damage. It is widely recognized that the corrosion of carbon steel in soil, water and soil-water interface proceeds according to the following simplified anodic reaction and cathodic reactions in the presence of oxygen (Decker et al. 2008)."

Jan 1, 2017

By Lewis Robert M.

The importance of phosphate in feeding the people of the world has been recognized by mining companies as they continue their search for new ore deposits and ways of improving phosphate production. An extensive phosphate-recovery research project involving investigation of beneficiation variables by batch testing, flotation pilot-plant processing of the major portion of the ore, gravity separation of the coarse fraction, and recovery of byproduct heavy minerals of a North Carolina phosphate deposit has been completed. Data obtained through batch tests enabled the development of an economical flowsheet which proved successful for the efficient recovery of a good quality phosphate concentrate in a pilot plant.

Jan 1, 1975

By X. J. Lyu, Q. Liu, M. J. Lian, X. Q. Cao, X. F. You, B. O. Erdenekhuyag, H. Y. Zang

The slag-tailings based artificial reef concrete (ARC) is made of CaO-CaSO4 activated granulated blast furnace slag (GBFS) as cementitious material and deslimed gold ore tailings as aggregate. In order to investigate the potential application of the material as ARC, the strength development, hydration characteristics and application performance were investigated under different preparation conditions. Results indicated that using seawater as the mixing water can effectively promote the hydration of slag and generate a large amount of hydration products such as ettringite, CSH gel, hydrotalcite and Friedel ’s salt in the early curing period and so render the material with good early compressive strength. Seawater curing can also accelerate the hydration reaction in the early stage of hydration. The hydration reaction of slag and the compressive strength of ARC can be effectively promoted by increasing the specific surface area of slag. The 28-day compressive strength of the slag-tailings based ARC prepared with 30-50% CaO-CaSO4 activated slag and 50-70% tailings can reach to 19.88-42.87 MPa. Also, the material has a low surface pH value, good resistance to chloride ion penetration, and sulfate corrosion. Keywords: Artificial reef concrete, granulated blast furnace slag, deslimed gold ore tailings, compressive strength, hydration characteristics

Jan 1, 2020

By O. A. Lima

Effective solids suspension is a necessary precondition for particle collection, and solids suspension is largely dependent on the hydrodynamics of the flotation cell. This study attempted to correlate the status of the suspension of apatite particles of different sizes in a Denver laboratory flotation cell versus the impeller rotational speed (N) adopted to operate the machine. The latter variable (N) influences the impeller capacity to lift the particles from the bottom of the tank and also to disperse them throughout the volume of the vessel. Such an impeller capacity can be characterized by the critical impeller speed for the accomplishment of solids off-bottom suspension (Nz) and also by the velocity of the radial water flow discharged by the impeller (U) divided by the particle terminal settling velocity (Us). This way, the status of the suspension of apatite particles inside the flotation cell can be characterized by one of three categories: ?segregation? (N/N2 < 0.60 and Us/U > 0.08); ?suspension? (0.60 = N/N2 < 1 and 0.06 < Us/U < 0.10); and ?dragging? (N/N2 = 1 and Us/U = 0.03). The range of impeller rotational speed (N), which was able to suspend the finest particles (Dp = 90 µm), was unable to suspend the coarsest particles (Dp = 254 µm). Conversely, the high value of N (N > 1,300 rpm), which is adequate to suspend the coarsest particles, may promote the entrainment of the finest particles to the froth layer.

Jan 1, 2009

By Thomas A. Cook

The effectiveness of tensioned roof bolt systems has been well researched and documented over the years (Stankus, 1990, 1991, 1997; Guo, 1997; Denton, 2000; Su, 2007). Higher and more consistent installed tension has been shown to improve the beaming effect and associated roof stability especially in highly-stressed, weak, laminated roof strata. To accomplish higher and more consistent bolt-installed tensions, various types of anti-friction washers have been developed and applied to many types of tensioned roof bolt systems. In addition to increasing bolt-installed tension, these washers also provide a lubricating effect that minimizes sparking during the bolt torqueing cycle. The most popular and widely used anti-friction washer configuration consists of a plastic washer that is used in conjunction with a standard hardened steel washer. This washer configuration has performed well in the field in terms of increasing the bolt-installed tension (or plate load) and the related tension/torque ratio (the amount of tension achieved per one ft-lb of applied torque). However, the installed tension does not always maintain consistency. One reason for this inconsistency is that the plastic anti-friction washer sometimes dislodges and shreds or tears before the bolt torqueing cycle is complete. This condition prevents the plastic washer from acting as an anti-friction medium for the entire torqueing cycle. Jennmar Corporation and Keystone Mining Services, LLC, developed the ?TT? washer in early 2012. The ?TT? anti-friction washer is comprised of two zinc-coated (galvanized) hardened steel washers that are joined together with an exclusive polymer. The ?TT? washer has been extensively tested and applied in the Sewickley, Pittsburgh, and Indiana #5 coal seams. The test results indicate an average increase in installed load and tension/torque ratio of 20%. More importantly, the installed load consistency improved, with a significant reduction in the standard deviation of values. This paper will detail the development and testing of the ?TT? anti-friction washer with case studies of actual mine applications.

Jan 1, 2014

By Allen S. Smith

Analysis of the helium content of a natural gas presents more than the usual difficulties encountered in applying the thermal-conductivity method because of the relatively small amounts of this inert as present and the wide variation in the other constituents. However, the numerous advantages of this method and its adaptability to Continuously recording and control instruments make it worthy of consideration. A specific application of the method described yields quantitative results only when used with gas mixtures of known qualitative compositions which Vary within predetermined limits. Periodic analyses for the helium content of a producing gas well may be conveniently made by an absorption method, and a continuums analytical method is not necessary for this purpose. Natural gas containing 1.75 to 1.90 percent of helium produced from Government-owned wells is processed in the Amarillo (Texas) Helium Plant of the Bureau of lanes. The helium extracted in the plant is supplied to the Army and Navy, and the processed natural gas is sold to a commercial gas company. As complete recovery of the helium in the raw material is not economically practicable, the processed gas contains 0.1 to 0.3 percent of helium, depending upon conditions of operation. Production is checked against the helium removed from the gas, which before the installation of the thermal-conductivity apparatus was calculated from the analysis of a cumulative sample of the processed gas. As conditions of operation affect the residual helium content to a large extent, a composite sample was an uncertain index of the efficiency of the process.

Jan 1, 1934

By Edgard Atencia, Cristian Cerrón

Los análisis y resultados del siguiente trabajo están orientados al desarrollo de los factores claves que impactan al incremento de producción de la mina subterránea SMEB, teniendo como objetivo el incremento del flujo económico en cada proceso de la mina subterránea (throughput).

Sep 29, 2023

By D. Minney

The quality of resin used in South African collieries is currently controlled according to South African Bureau of Standards, "SABS-1534:2002". It has however been found that resin which passed the SABS tests failed in underground short encapsulation pull tests. An investigation was therefore conducted to determine the characteristics of resins that are currently being used in collieries. A series of in situ short encapsulated pull tests was conducted to determine the effect of expired resin on support performance. The results showed that the longer the time after the expiry date the poorer the resin performance. A series of resin-torque tests has been performed using Anglo Coal&apos;s testing facility. The following parameters were investigated on different resins: Spinning speed, Mixing time, and Setting time. An attempt was also made to develop a new quality control procedure for resin. This procedure enables mining personnel to make sure that the quality of resin can provide the required support performance. The effect of spinning speed on resin performance was also investigated. The results showed the resin gelling times of resin decreases as the spinning speed increases. It is found that over-spinning with slow speed roofbolters may result in decreased bond strengths. It was found that a 30-second resin (10-second spin, 30-second hold) should never be spun more than 20 seconds, even with very slow roofbolters (100 rpm).

Jan 1, 2005

By D. Whittles, S. Kingman, S. Bradshaw, N. Miles

The influence of microwave energy at high electric field strength on ore strength has been investigated. Two ores of varying mineralogy were treated in both multimode and single mode microwave cavities. After treatment, any change in strength relative to untreated ore was established. It was shown that in the multimode cavity reduction in strength was related to the applied power level. Results of tests carried out in the single mode cavities showed that, for both ores, reductions in ore strength > 50% could be achieved in very short periods (<1 second). Thermal stress analysis showed that the mechanism of microwave induced failure was the development of tangential stresses at the grain boundaries. It was concluded that operation at 915 MHz with high power and short residence times gives feasible scale-up possibilities.

Jan 1, 2003

On April 1, 1982, the Bureau of Mines and the Department of Energy entered into an Interagency Agreement to develop an enhanced computer cost model for uranium in situ leach mining. The original computer cost model contained data base information related to two regions; the Wyoming basin region and the South Texas trend area. The enhanced cost model contains additional information on San Juan Basin type deposits. This addition is significant because it expands the model&apos;s capabilites to include one of the largest uranium producing areas in the United States and developes costs related to uranium production from in situ leach mining. The data base was expanded and modified to include changes necessary for San Juan basin type deposits. These changes included, but were not limited to, state and local taxes, royalty payments, depth of deposits, drilling costs, and electrical costs. Also site visits were taken to verify many of the base case parameters. Consequently, the data base has been incorporated into the computer program and existing software was modified to provide for the additional data. Information was obtained on drilling coats and therefore the current program more accurately reflects these costs to depths of 2500 feet. This depth parameter has been expanded to include Wyoming Basin and South Texas scenarios also. Verbal communications were held with one operator in the Crownpoint, New Mexico area as well as the state regulatory agencies to help validate the expanded model. As a result of these changes, several tables have been included, summarizing changes in the new default parameters and the overall range of input parameters.

Jan 1, 1982

By A. F. Silva, J. M. G. Sotomayor, V. F. N. Torres

Geotechnical monitoring plays an important role in the detection of operational safety issues in the slopes of open pits. Currently, monitoring companies offer several solutions involving robust technologies that boast highly reliable data and the ability to control risky conditions. The monitoring data must be processed and analysed so as to allow the results to be used for several purposes, thereby providing information that can be used to manage operational actions and optimize mining plans or engineering projects. In this work we analysed monitoring data (pore pressure and displacement) and its correlation with the tension and displacement of the mass of an established failure slope calculated using the finite element method. To optimize the back-analysis, a Python language routine was developed using input data (point coordinates, parameter matrix, and critical section) to use software with the rock mass parameters (cohesion, friction angle, Young’s modulus, and Poisson’s ratio). For the back-analysis, the Mohr-Coulomb criterion was applied with the shear strength reduction technique to obtain the strength reduction factor. The results were consistent with both the measured displacements and the maximum deformation contours, revealing the possible failure mechanism, allowing the strength parameters to be calibrated according to the slope failure conditions, and providing information about the contribution of each variable (parameter) to the slope failure in the study area.

Oct 1, 2021

By C Placzek, E Beattie, K Blake

Channel iron deposits (CID) consist of ferruginous chemical sediments, and are an unusual subset of Phanerozoic ooidal ironstone deposits almost unique to the Pilbara, where they constitute around 19 per cent of the Pilbara’s iron ore exports. These deposits occupy many of the ancestral river channels of the Pilbara region, especially the Robe River palaeochannels, incising and meandering through the Precambrian banded iron formations (BIF) of the Hamersley Group and the underlying Fortescue Volcanics.This paper explores the factors underlying geochemical variation in CID, particularly the chemical properties of goethite. The selected deposits in the western Robe palaeochannel and its tributaries show little or no secondary reworking by later water tables. There is a total absence of aluminosilicate clays with all the deleterious elements such as aluminium and silica. Instead, these are associated with the goethite mineral lattice, either within or adsorbed to the cortices of pelletoids.A thickly vegetated environment, and the presence of the Maddina Volcanics as potential source rocks for these western Robe CID is offered as an explanation for relatively high aluminium in the deposits studied, and, in turn, as the reason most parts of the palaeochannel are preserved as inverted topography.CITATION:Beattie, E, Placzek, C and Blake, K, 2017. Dirty goethite – a geochemical characterisation of some western Robe River channel iron deposits, in Proceedings Iron Ore 2017, pp 489–502 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 24, 2017