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By Donald P. Tuchman, Emanuele G. Cauda, Steven E. Mischler, Elaine N. Rubinstein, Jay F. Colinet

The PDM3600 and PDM3700 are two closely related person-wearable dust monitors manufactured by Thermo Fisher Scientific. Both are based on tapered element oscillating microbalance technology and provide nearly real-time, mass-based readings of respirable dust concentrations. From a monitoring perspective, the primary difference between the models is the PDM3600 has an integrated cap lamp with attached inlet, while the PDM3700 has no cap lamp and a revised inlet attaches to the worker’s lapel. Using coals of varied origin and employing a wide range of concentrations, side-by-side measurements from these instruments were collected under controlled laboratory conditions and then compared. By use of ordinary least squares and weighted least squares regression methods, followed by mixed model analysis, results suggest there is no statistically significant or practical difference in instrument performance. The two monitors are equivalent for the field dust concentration measurements for which they were designed.

Feb 28, 2024

During 2009 the technical services staff at Barrick Gold Corporation's Australian Business Unit conducted a review of their five underground mines that utilise pastefill as the backfill component for these operations. Of the five mines reviewed three use dry tailings and two use wet tailings plants. The primary aim for these reviews was to determine whether pastefill was the right option to be used, and if not, what where the alternatives. The reviews undertaken focus on several areas including, paste plant operation, reticulation and barricade techniques, the geotechnical requirements for pastefill in regards to the current mining methods, the consideration of alternative methods, capital and operating cost histories compared to initial estimates, and a cost benefit analysis of pastefill against other mining methods. The main benefits from the use of pastefill is increasing the extraction of the resource, reducing or eliminating the need to leave pillars. In some mines the use of pastefill is geotechnically driven, to manage high stress environments or mining induced seismicity. A third benefit of using pastefill in some circumstances is that it reduces dilution, however it is considered that this is not a valid argument for most of the mines reviewed. At two mines no alternative to pastefill was determined, whilst differing extraction and filling strategies were potentially identified at the other three mines. The reviews developed cost benefit curves for those sites that had alternative mining methods to assist in determining whether pastefill is the right option to use for any particular stope. At the grades typically mined in each operation, pastefill was the preferred option to use. In all mines, pastefill was determined to be the best option at this time.

Nov 25, 2010

By G. R. Hopkins, E. M. SEELEY

According to reports received by the Bureau of Mines, Department of Commerce, as of Jamary 1, 1930, there were 1,035 natural-gasoline plants in the United States, with a total daily capacity of 10,516,000 gallons. (These data do not include one small plant in Alaska.) The last similar survey, that of Jamary 1, 1928, showed a total of 1,155 plants of 8,048,000 gallons daily capa- city. This in two years time the number of plants has decreased by 120, but the total capacity has increased 2,468,000 gallons or 31 per cent. This is roughly equivalent to the gain in production over the same periodi Over half of the increase in total capacity was registered in California, where the development of flush oil production having a comparatively high gas-oil ratio in such fields as Santa Fe Springs led to construction of some new plants and material enlargement of others. Of the total plants, 999 were operating on Jamary 1, 1930, and 36 were shut down. This compares with 1,060 operating and 95 shut down two years ago, which indicates a tendency to dismantle plants as soon as they become obsolete or umrofitable. The total daily capacity of the plants operating on Jamiary 1, 1930, amounted to 10,278,000 gallons, or 98 per cent of the total, leaving only 238,000 gallons, or 2 per cent, for the shut-down plants. This contrasts with the refining industry, which usually has 5 per cent of its total capacity idle; the difference is due to the relative ease with which a refiner can secure a crude supply as against the difficulty the natural gasoline manufacturer has in reestablishing his gas connections. During 1929 the average total daily capacity of the operating plants was 9,899,000 gallons, while the average daily production amounted to 6,015,000 gallons. This indicates that the plants operated during 1929 at 61 per cent of their capacity. Although over 60 plants were dismantled in Oklahoma during 1929 the State continued to rank first in total mumber. California was second in mumber of plants with 165, and was one of the few States that showed a gain since the

Jul 1, 1930

By Levent Ozdemir

An extensive study involving laboratory testing and computer modeling has been performed to assess the technical and economic feasibility of utilizing the recently developed minidisc cutters on roadheaders for hard rock mining. The results show that heavy duty roadheaders fitted with minidiscs can excavate hard rock formations at acceptable production rates and cutter costs. This paper presents and discusses the results of this study together with the ongoing developmental efforts of this technology, which include laboratory testing of a roadheader cutting drum with minidiscs and full scale field testing of a machine in hard rock

Jan 1, 1995

By Nobuhiro Kuriyama

Electrochemical activation behavior of an AB2-Laves-phase type hydrogen storage alloy, Zr0,9Ti0.lNi1.lCo0.1Mn0.6V0.2 was studied to make clear activation process of pellet-type metal hydride electrodes. An alkaline treatment of the electrodes with heated alkaline solution gave alloy surface enriched with nickel, and the treated electrode was more easily activated. The treated electrode desorbed more hydrogen during the first charge-discharge cycle, and was activated without induction period. A cross sectional view of the activated electrode showed finer pulverization of alloy particles than the annealed alloy, and impedance spectroscopy indicated larger surface area of the electrode using the as-cast alloy. Since the as-cast alloy contains inhomogeneities, multi-phase microstructure and stress in the particle, the finer pulverization of alloy particles with hydrogenation are considered to increase surface area in an earlier cycle in the case of the as-cast alloy, which leads larger reaction area and faster activation of the as-cast alloy electrode.

Jan 1, 2002

By James McNally, Adam Stremcha, John MacGregor

With 13.7km of TBM tunneling in Atlanta’s hard gneiss well under way, drill and shoot work continues on several sites throughout the city. In order for the City of Atlanta to meet the consent decree imposed by the federal government, an aggressive construction schedule was a necessity. Construction consists of two deep, large diameter tunnels, four construction shafts, a pumping station, one overflow shaft, three large intake structures, and two connecting tunnels. Due to the multitude of blasting insensitive urban environments, a high standard of seismic and air-overpressure criteria, coupled with time restrictions, was adopted for the project. At any given time, drill and blast operations were under way at four of the seven sites requiring a certain amount of coordination between the TBM excavation, surface work, and the forces of Mother Nature. This paper addresses the challenges faced and the techniques used to safely and successfully complete the rock excavation of the West Area CSO Tunnel and Pumping Station project.

Jan 1, 2007

By E. Lentilucci, A. Dey, X. Liu, A. Datta, S. Ghosh

The segmentation of quarry blast smoke plumes is a crucial research area that has the potential to enhance safety, environmental monitoring, object detection, and regulatory compliance in the mining industry. Smoke plume segmentation can be used to identify the spatial extent and temporal evolution of smoke plumes generated by the blast. This information can be used to improve the understanding of blast dynamics and optimize blast designs. Furthermore, smoke plume segmentation can assist in identifying potential environmental and health hazards associated with the release of smoke and dust particles into the atmosphere during quarry blasts. However, many current smoke plume segmentation algorithms are designed for segmentation of smoke plumes from fires and are not suitable for segmentation of plumes from quarry blasts. The proposed method in this paper leverages the video frame captured before the blast as a stationary background image, which helps to reduce other confuser objects present in the image along with a selfadaptive clustering method. The color channels of the image are utilized based on the different contrast properties of the smoke, with a self-adaptive gradient compensation applied for edge detection of the smoke plume. This approach offers a novel and effective way to segment smoke in quarry blast analysis, with potential applications in the calculation of noxious gas volume and concentration within the plume. Compared to other algorithms, our method improves accuracy, decreases the false alarm rates, and reduces the overall miss rate. Overall, this paper contributes to the research on smoke plume image segmentation, particularly for quarry blast smoke plumes, which possess unique characteristics that require specialized algorithms for accurate segmentation.

Jan 1, 2024

By R. Heath Forbes

The route of a new, 4-mile long, electrical transmission line passed through residential neighborhoods and commercial areas of a small town in the South Carolina Coastal Plain. The new line consisted of 54 new poles and a one-mile underground section. Most of the new poles were constructed within 50 ft of existing structures, and in some cases, within 8 ft to 20 ft. A widely-space subsurface exploration consisting of 20 cone penetration test soundings indicated the subsurface conditions along the alignment generally consisted of saturated, loose to medium dense, fine slightly silty to silty sand. The pole foundations consisted of 20 to 30 ft long, prefabricated ?caissons? (essentially an open-end pipe pile with a prefabricated connection system at the top) with diameters of 28 to 56 inches. The steel caissons were installed with vibratory pile hammers. To help prevent damage and defend against possible allegations from nearby property owners, vibration and settlement monitoring was performed during all foundation installation activities. Limited structural condition assessments were also performed before and after foundation installation. For 53 of the 54 foundations, the ground vibrations recorded at distances coincident with the nearest structure locations ranged from 0.05 inches per second to 1.46 inches per second. With consideration of the dominant frequency, the majority of these values were below the commonly used USBM vibration limits. For a foundation installation that was only 8 ft from the nearest structure, a peak particle velocity of 3.06 inches per second was recorded, which exceeded the USBM limits. For all cases, the measured ground surface settlement was negligible (i.e., less than ¾ inch). Several spurious claims alleging vibration-induced damage were made, but the monitoring program provided an adequate defense. One claim involving artwork that fell to the floor during foundation installation at a distance of 8 ft from the house was deemed legitimate.

Jan 1, 2011

By L. E. Djingheuzian

"ForewordTHE FOLLOWING excerpt is taken from Fine Grinding Investigations at Lake Shore Mines (C.I.M., Trans., Vol. XLIII, 1940, p. 307):""MacCalman, who has carried out exhaustive testing on the accuracy of screen analysis, makes the following statement in his report, The Accuracy of Sieving Tests, Industrial Chemistry (London, England), Vol. XIV, p. 231:"" 'It will be shown that, as no specific relationship between the sieving value and the various dimensional features of the sieve is evident, though there is an apparent tendency for the sieving value to follow the average aperture size, it is apparently impossible to define the sieving value of a screen from dimensions alone, and the calibration of sieves for important tests on a specific material, whereby the sieving values of these sieves are related to that of an arbitrarily chosen master sieve by correction values, will be recommended."" 'It will be emphasized that these correction values are probably not applicable to other materials, or the same material of different size composition. Sieve users, for important tests or in cases of dispute, will be recommended to calibrate their sieves against a mutually acceptable standard with specified conditions of test, and to recalibrate at intervals' ""."

Jan 1, 1953

By F. B. Olender

Idler engineering, operation, and maintenance cannot be covered in depth in a short paper. Therefore, this will be a general look into the subject matter in light or the present-day technology. Depending on the source or reference used, belts for handling bulk material underground came into being between 1900 and 1920, while strip mining appeared in the thirties. The conveyor belt speeds in that era were in the 300 rpm to 500 rpm range. Belt speeds or 600-700 rpm were in vogue in the thirties, and the early sixties saw speeds or 800-900 rpm. Today, speeds or 1000 rpm are not looked at with dismay; in fact, speeds or 2000 rpm are being discussed. Among the driving forces moving the bulk materials handling industry to these greater heights have been the mining operators and engineers. Their appetite to increase output, yield, and reduced per-ton costs has constantly challenged the bulk material handling industry to develop products capable or handling these increased capacities. One or the products affected by this movement is the idler. Apart from the conveyor belt itself, it is one or the most significant parts or a conveyor system because or the sheer numbers needed in an installation.

Jan 1, 1971

By JOHN A. FULTON

THE Comstock Lode is in Storey County, Nevada, and extends in a north and south direction through the towns of Virginia City and Gold Hill, with a total length of 4.27 miles. Its mines have produced silver and gold to a known value exceeding $400,- 000,000 since 1859, when the work first began. More than $126.000,000 was paid in dividends by the mining companies, although much more than this was probably realized from the ore, because many milling companies were independent companies owned by the directors and superintendents of the mines. The milling companies' contracts called for an extraction of only 65 per cent and, as much of the ore was worth $100 a ton and up- ward, they must have recovered substantial amounts for their own accounts over and above this guarantee. Gold was discovered in the spring of 1850 by a party of Normons bound for California. The discovery was made at the mouth of Gold canyon near Dayton, on the Carson River, about 10 miles south of Virginia City.

Jan 1, 1929

By Y. Luo

The rock breakage process in drilling is a main source of noise in roof bolting operations, especially when hard rocks are encountered. Proper control of drilling operation can provide an opportunity to improve energy efficiency of drilling and to reduce noise and heat generated from bit-rock friction. Drilling tests have been conducted in laboratory settings to confirm this noise-reduction strategy. Preliminary results show that the drilling parameters, penetration and rotational rates can be controlled to achieve in a desirable range in drilling medium hard rock. Based on the theoretical and experimental studies, rational drilling control strategy is developed for noise control while maintaining a safe and productive roof bolting operation. Applying this strategy in underground roof bolting operation, the noise exposure of roof bolter operators will be significantly reduced.

Aug 1, 2013

Jan 1, 1885

One common public perception of mining is that financially it is an extraordinarily risky business. Another and contrary view, in certain circles, is that price risk and other financial risks can be relatively easily removed or shifted by a number of schemes or devices. In reality, beyond the orebody discovery stage, mining need not be any more risky than most heavy industrial businesses. Nevertheless, as stated by Rappaport, (1986): Risk is a parameter of central importance in establishing the economic value of any asset. The level of risk is determined both by the nature of the firm's operations and by the relative proportions of debt and equity used to finance its investments. These two types of risk are commonly referred to as 'business risk' and 'financial risk' respectively. The term financial risk is used somewhat more loosely herein to recognise the reality that any risk inadequately addressed in the design, construction and operation of a mining project can have significant financial consequences; usually negative. For instance, a specific area of business risk in mining is often called technical risk which definitely has severe financial consequences if not managed correctly. The various risk shifting, hedging and risk management tools available all have their place and range from merely useful to almost indispensable. However, in the long-term, financial risks are maintained at acceptable levels by the application of sound, more fundamental business management principles. There are many with a vested interest in perpetuating a perception that the conceptual foundations of sound management practice are extremely complex. In reality, most management concepts are prosaic, but their application requires incredible discipline and hard work. There is no magic formula or 'silver bullet'. It appears that a company whose activities are restricted to mining can analyse the range of risks specific to mine development and operations more clearly than companies in which mining is just one of many businesses. The almost universal failure of large oil companies in the mining business is probably the best example of lack of any clear comprehension of fundamental business characteristics and risks. Conversely, in regard to risk management, choosing to be in other business as well as mining does nothing to reduce the risks of the mining business. The individual shareholder can probably make such 'diversification of portfolio' decisions better than most management teams. It could be argued that diversification across a number of disparate businesses may actually increase overall corporate risk due to lack of management concentration and focus. These differences between the perceptions of financial risks and the realities in mining need to be further elaborated in relation to some uncompromising business concepts.

Jan 1, 1994

By F Djukic, T Fisher, G Irving

Questionnaires were sent to 12 underground metalliferous mines in Queensland to enquire how these mines control diesel emissions from mobile diesel engines used underground. Where responses or controls were absent, discussion has been provided. A significant finding concerns secondary ventilation design rates. Some mines were designing ventilation rates to meet the superseded Mines Regulation Act of 1989 which required 0.04 m3/s/kW. The current Queensland Mining and Quarrying Safety and Health Regulation (2001) is risk based. In line with other jurisdictions, including New South Wales (NSW) and most Provinces in Canada, a minimum ventilation rate of 0.06 m3/s/kW is acceptable. However, this design ventilation rate will vary in practice depending on the diesel engines and controls. Dedicated ventilation engineers and technicians should be appointed to evaluate the effectiveness of the ventilation system. Personal exposure monitoring is required to confirm that exposure standards are not being exceeded. The primary control practice should be to reduce the emission at source. This can be ensured by purchasing low emission (Tier 2, Tier 3) equipment. In addition, the use of ultra low sulfur fuel (et al, 2002). Diesel fuel with a low aromatic content such as Eromanga diesel fuel will also mean employees are exposed to lower levels of poly-cyclic aromatic hydrocarbons. These controls should be carried out in parallel with good maintenance practices. Preventative maintenance should be programmed and emissions be routinely tested, including both gaseous and particulate pollutants and compared against defined criteria. According to McGinn, 2002, there are a number of fundamental tools necessary to carry out preventative maintenance. These are outlined in maintenance guidelines and best practices for diesel engines in underground mining produced for the Diesel Emissions Evaluation Program (DEEP). An effective diesel emission management system needs to be fully integrated within the Safety and Health Management System. These requirements are further discussed in this paper.

Jan 1, 2007

By William J. Francart, Edward J. Miller

The utilization of computer based monitoring systems for fire detection in underground coal mines has grown significantly in the past seven years. In 1984, an annual MSHA survey identified a total of 38 systems being used in U.S. underground coal mines, while a 1990 survey indicated the number has risen to 112. The applications for mine monitoring have also changed according to the annual surveys. From April 24 to June 21, 1990, investigations were conducted by personnel of the Ventilation Division, Pittsburgh Health Technology Center, in cooperation with Coal Mine Safety and Health, concerning the installation and operation of Atmospheric Monitoring Systems in underground coal mines. These investigations were conducted to gather information concerning the ability of the AMS to detect fires and heatings, false and nuisance alarm frequencies, information related to system maintenance, and information related to employee training on system operations. This paper addresses current applications of the systems, fire and heating identification rates, application of systems in dieselized coal mines, system maintenance, and employee training requirements. While deficiencies were identified in some applications, results of the studies and survey indicate the use of atmospheric monitoring systems can be effective in identifying mine fires and heatings.

Jan 1, 1991

By Kimberly Conner-Mills

Due to increasingly stringent worldwide environmental regulations for gaseous, aqueous and solid waste emissions, conventional smelting technology cannot effectively process arsenic containing materials. Many globally significant copper properties have copper sulfide mineralogy that has a high arsenic content present as enargite with significant contained precious metals. As global copper, silver and gold demand increases while significant world resources decrease, treatment of sulfide orebodies with enargite is becoming increasingly important. Methods to selectively dissolve and fix arsenic, leaving behind clean copper and precious metals-bearing concentrates could effectively treat these ores.

By J. Font

The RAF or copper fire refining process at the Caletones smelter of CodelcoChile consists of several pyrorefining stages that successively lowers the levels of S, Fe, Pb, As, Sb, Te, Se and to some extent 0 in the copper melt, allowing the production of high quality fire-refined copper of 99.93 % purity (RAF copper). This chemical feature of the RAF copper is only achieved by quite long processing times, and a considerable consumption of fluxes and fuels in the RAF vessels. The main goal of this study was to improve the RAF process performance by thermodynamic considerations and industrial scale tests, i.e., an in situ approach for the process as featured by intensive sampling, characterization and subsequent modifications. Thus, both theoretical and industrial data were derived, and based on kinetic and thermodynamic evaluations, a higher operational standard was achieved for the RAF process. These new operational practices allowed enhancing the overall economic of the RAF process, by reducing the time and operational costs, and consequently increasing the availability of the vessels.

Jan 1, 2007

By A. Hutwalker, T. Plett

"Blast fumes are one of the major sources for NOx in underground mines. In 2016, the Occupational Exposure Limits for NOx in Germany were reduced by 90%. The task is to keep re-entry times after blasting at the present level and thereby ensure an economic operation of the mine. Measurements show that using ventilation solely is not sufficient. A new approach to reduce NOx from blast fumes is described. Laboratory experiments were performed and a reduction of NOx was observed. Measurements were conducted at an explosive factory’s testing facility and in an underground mine at blasting operations. INTRODUCTION Whether for production of ore or for drift development, the processes in an underground mine are always the same: 1) fracturing the rock, 2) loading the pile, 3) support the resulting cavity. The fracturing of the rock can be done mechanically, by cutting, for example by using continuous miners or tunnel boring machines, or by drilling and blasting. Drilling and blasting is more flexible than mechanical driving, as it can be used independently of the rock strength. Furthermore, this driving method allows a more flexible reaction to changes in geological and/or operational conditions. Thus, underground mining and blasting are almost inextricably linked with each other, and regardless of the size and level of technology of the mine, blasting is hardly avoidable. Depending on the mining method chosen and the existing framework conditions, such as the mechanical properties of the rock or the availability of machinery, blasting is an integral part of daily operations. Even in mines where blasting is not part of regular operations, it cannot be completely avoided. The blast fumes generated by the explosions are, in addition to diesel engine emissions, one of the two main sources of emissions of nitrous gases underground. Up to now, state of the art for dealing with blast fumes is ventilation. The fumes are diluted with fresh air and ventilated out of the mine. This treatment of blast fumes is more than sufficient with the former German Occupational Exposure Limits (OEL). The adaption of the OEL in Germany to the recommendations of the Committee on Occupational Exposure Limits (SCOEL), a committee of the European Commission, leads to big challenges for the mining industry in reducing the concentrations of these gases at the workplaces underground. On its meeting on May 2nd and 3rd 2016, the Committee on Hazardous Substances (Ausschuss für Gefahrstoffe, AGS), an advisory body of the German Federal Ministry of Labour and Social Affairs (BMAS), advised the BMAS to copy the OEL, as recommended by the SCOEL, to the Technical Rules for Hazardous Substances (TRGS 900). BMAS followed this advice, consequently the new OEL where published on November 4th 2016 and became part of the TRGS 900. Table 1 shows the former and new OEL for Germany. These new OEL became law after publishing, but two exceptions were made: For tunneling operations, they became law on October 31st 2017, for mining operations they will become law on October 31st 2021 (BAuA, 2004, 2016, 2017)."

Jan 1, 2019

By T. W. West

INTRODUCTION This paper presents an assessment of conventional flotation technology. In addition it presents some ideas which can be used to change the perception of what may be done with conventional flotation equipment to maximize its efficiency. Perspective of Conventional Flotation Technology 1. Flotation in many coal preparation plants is defined as something between a necessary evil and a non-viable concept because: -Too much art is required on a continuous basis to achieve uniformly acceptable results. -It is expensive, the capital cost in dollars per ton of circuit feed for flotation and dewatering is high. -It is a difficult process to use when SO2 reduction governs system design and equipment selection. -It creates a product (fine coal froth) that is difficult to dewater in the presence of BTU/lb as-received pressures. -It is a difficult process to control from a management standpoint, there are no dependable set points to rely on. 2. Many froth cell circuits are 0.5m x 0 (nominal 28 M x 0) feed which is sourced from screen/cyclone underflows. The original intent was to obtain maximum yield at acceptable product quality and moisture using disc filters. (See Figure #1) 3. An alternate to conventional flotation and its perceived to be limits of efficiency, capital costs, etc. is to move towards such developing flotation technologies as column flotation, reverse flotation, and microbubbles. A lot of work is being done to move these concepts thru pilot stages into full scale, commercial plant operation. The majority of the coal producers and coal preparation plant designers view these concepts as being in the development/pilot plant stages. OBJECTIVES Based on the preceeding comments of the perspectives of the coal producers and plant designers, the options are limited. They can make do with what they have available to them in the way of industry standard equipment and practices or they can move forward with developing technology. I feel there is a third option: what can we really do today with what is available to us, without reinventing the wheel? APPROACH 1. When processing coal against ash and SO2 restrictions, the fine clean coal stream can be the best stream on the clean coal conveyor due to the release by size and the ability to create a high BTU/low sulfur (dry basis) product. 2. Targets: -Consistent raw coal size consist in the plant feed . -Do not put pyrites in the froth cells. -Adjust criteria defining good flotation away from yield towards maximum BTU recovery at minimum ash. -Limit the froth cell feed size consist to 0.15 mm x 0 (nominal 100M x 0). -Establish and maintain a correct, consistent percent solids in the froth cell feed. -Select flotation reagents with care. -Introduce reagents in the proper sequence.

Jan 1, 1988