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The Objective: To reduce the noise generated by the exhausting air from a pneumatic roof bolting drill to a maximum of 90 decibels. Any attachment used for this purpose must be lightweight and must not cause a significant increase in back pressure. The Approach: Absorb the noise with a properly designed muffler that will permit sufficient airflow without affecting the normal operation of the drill. How It Works: The air exhausted by the drill enters the muffler through perforated disks into a resonator chamber. It then passes through a series of expansion and contraction chambers and is expelled to the atmosphere through another perforated disk. The basic muffler design for the pneumatic drill was established by using both digital computer analysis and experimentally simulated noise tests. The measured parameters used in the computer program consisted of inlet and outlet pressures, temperatures, airflows and exhaust areas. United

By K. J. Craig, M. A. Swart, Q. G. Reynolds, L. Hockaday

A solar reflector soiling study was carried out at a ferromanganese smelter in South Africa to assess the soiling rates at different locations around the plant. Several meteorological parameters were monitored to give insight into the conditions that lead to increased soiling. Mineralogical characterization of dust samples collected from the reflectors and the atmosphere revealed that only a certain size fraction is of importance with regard to soiling, and that the dust can be attributed to both raw materials and smelter products. Proximity to the dust source was the primary driver for increased soiling. The site that experienced the most soiling was very close to raw material heaps; this was deemed an outlier and was excluded from the summary statistics. The secondary driver for increased soiling was location relative to the smelter dust sources and the wind’s direction and speed. The reflector set at the best location experienced 13.1% less soiling than the set at the ‘worst’ (but still feasible) location, represented by an averaged mean daily reflectance loss of 0.0186. The study revealed that while there are periods of intense soiling at this particular site, proper planning of reflector location in relation to the smelter dust sources can significantly mitigate the soiling rate.

Jun 5, 2023

By J. N. Van der Merwe, D. P. Roberts

The two components of pillar design formula being used in South Africa are pillar strength and pillar load. While considerable effort has been directed to the determination of pillar strength, the other half of the safety factor equation, the load, has not received the same amount of attention. The load acting on pillars has always been calculated using the Tributary Area Theory (TAT). This paper summarises the recent studies on coal pillar loading using various numerical models. It concludes that although there are meaningful differences under certain circumstances, there is still a compelling argument to use the TAT in coal pillar design. Les deux parties composantes de la formule de conception de pilier généralement utilisée en Afrique du Sud sont la résistance de pilier et la charge de pilier. Tandis que des efforts considérables on été dirigés vers la détermination de la résistance de pilier, l’autre moitié du facteur de sécurité n’a pas reçu la même attention. La charge agissant sur les piliers a toujours été calculée avec la Théorie d’Aire Tributaire (TAT). L’étude présente résume les études récentes sur la charge de pilier de charbon utilisant des modèles numériques variés. La conclusion est que bien qu’il y ait des différences significatives selon les circonstances, il y a toujours un argument puissant pour utiliser le TAT dans la conception de pilier de charbon. Die in Südafrika für die Auslegung von Pfeilern verwendeten zwei Formelkomponenten sind Pfeilerstärke und Pfeilerbelastung. Während beträchtlicher Aufwand zur Bestimmung der Pfeilerstärke gemacht wurde, wurde der anderen Hälfte der Sicherheitsfaktorsgleichung nicht die gleiche Aufmerksamkeit gewidmet. Die auf die Pfeiler wirkende Last wurde immer unter Verwendung der Tributary Area Theory (TAT) berechnet. Diese Arbeit fast neuere Studien betreffend der Belastung von Kohlepfeilern unter Verwendung verschiedener numerischer Modelle zusammen. Die Schlussfolderung ist, daß obwohl unter bestimmten Vorraussetzungen bedeutende Unterschiede existieren, nach wie vor ein bezwingendes Argument besteht TAT in der Kohlepfeilerauslegung zu verwenden.

Jan 1, 2003

By H. Q. Fan

Construction equipment is an important type of resources of heavy construction contractors. Since equipment breakdowns can cause project delays and significant financial losses, the contractors are eager to know those factors causing equipment failures directly or indirectly, related to equipment design, maintenance, and operations. Although Bayesian network can be used for diagnostic analysis of failure events or making predictive analysis, building a Bayesian network for such purpose can be difficult as the cause-effect relations can be subjective and their conditional probabilities change with a wide variety of causal factors. A hybrid approach is proposed in this paper to update the Bayesian diagnostic network structures and parameters using real life data, the conditional probabilities and cause-effect relationships can be dynamically updated with observed failure records to reflect the real life situations of a complex equipment system. A case study is conducted to show the benefits of the hybrid approach in construction equipment diagnostic analysis.

Aug 1, 2013

By William E. Souder

The behavioral accident simulator (BAS) is a computer program that can be used to simulate accident situations. It demonstrates how the potential to have an accident grows or diminishes as a result of changes in various environmental, organizational, and behavioral factors. It calculates the number of fatalities that may result from various conditions and graphically displays these data. The BAS is useful for studying systems of accident causes, for demonstrating the various ways to diminish fatalities, and for training employees. This Bureau of Mines report provides the detailed instructions needed to use the BAS.

Jan 1, 1988

[Chairman ZAY JEFFRIES, Vice-chairman S. SKOWRONSKI, Chairman WILLIAM M, CORSE, Secretary Executive Committee J. R. FREEMAN, JR., Local Section G. E. JOHNSON R. S. ARCHER, Non-ferrous Data Sheets P. D. MERICA EDGAR C. BAIN, Journal Committee L. W. SPRING SAM TOUR, Papers Committee F. L. WOLF H. C. JENNISON, Membership Committee Local Section Committee J. R. FREEMAN, JR., Chairman R. J. ANDERSON, Cincinnati R L. DOWDELL, Minneapolis R. S. WILLIAMS, Boston G. H. CLAMER, Philadelphia W. A. SCHEUCH, Chicago R. F, Woon, New York Papers Committee S. SKOWRONSKI, Chairman F. H. DIx, JR.-Aluminum E. R. DARBY-Bronze C. S. WITH ERELL-Copper H. A. BEDWORTH-Brass W. K. FRANK-BRONZE F. W. HARRIS-Copper R. L. SUHL-Nickel H. M. ST. JOHN--Foundry Metallurgy R. S. DEAN-Theoretical Metallurgy]

Jan 1, 1928

Mercapto organic compound SDMP was used as a depressant for separation of copper activated marmatite from pyrrhotite in the presence of butyl xanthate. Flotation results show that SDMP has strong depressing effect on pyrrhotite recovery in the absence and presence of copper ion, but has promotional effect on marmatite recovery when added together with copper ion. The flotation test of mineral mixtures shows that copper-activated marmatite could be separated efficiently from pyrrhotite using SDMP as depressant. Infrared adsorption spectra demonstrate that SDMP has a strong adsorption on pyrrhotite surface through its functional groups such as ?SH, -S03.

Jan 1, 2006

By D. Kruse, M. Sanaei

"A three dimensional nonlinear finite element model was constructed to simulate and analyze the behavior of large diameter segmentally lined shafts when subjected to seismic waves. To reduce computation time, a less complex shell model was also constructed. Transient excitation was applied to the supported nodes of both models, at the base of the shaft, with a time-function representing the 1994 Northridge earthquake. The models are developed at the end of an original phased construction-stage analysis of the shaft. Displacements, forces and moments are monitored and compared during the analyses steps. During the initial 15 seconds of the earthquake, the top and bottom of the shaft show similar displacements. The maximum horizontal displacement within the shaft is approximately 3.5 inches in the solid model and the shell model results conform to this by a factor of 50%. Keywords: Segmentally Lined Shaft, Soil Structure Interaction, Seismic Analysis, Finite Element Modeling, Ground Modification INTRODUCTION TO SEGMENTALLY LINED SHAFTS Large diameter segmentally lined shafts (SLS) are underground systems, constructed sequentially using precast concrete segments to form a ring which provides both temporary earth support during excavation and permanent structural support. The segments are connected via alignment pins, bolts, packer material and other structural components that ensure the continuity of the SLS. In this analysis, the construction process uses a top-down sequence wherein each soil layer is excavated, damp-proofing is installed and concrete segments are assembled to form each ring. This process is repeated until design depths are achieved completing the shaft. It is known that cylindrical structures sustain lateral (earth) pressure mainly through the mechanism of hoop-stress. As Timoshenko’s ring theory goes, a cylinder shell structure is prone to buckling under external pressure [1]. In typical designs of small diameter shafts and tunnel linings with small diameter to wall thickness ratios, nonlinear buckling analysis (i.e., nonlinear geometric analysis) is not considered, since the buckling capacities for those structures are much higher than typical pressures encountered at their design depths. However, in shafts with large diameter to wall thickness ratios, buckling could become a critical issue. In any given mode, as buckling occurs in a ring, some sections of the structure move inward while alternating sections protrude. Although the presence of the surrounding soil could mitigate the buckling by resisting the movement (Soil structure interaction) seismic loads can cause ground movements and lateral pressures, exceeding the capacity of the structure. It is therefore essential to design the load bearing capacities of the shaft to minimize the possibility of any catastrophic failure due to earthquakes. This study explores the structural response of the SLS when subjected to seismic loads."

Jan 1, 2016

By Earl M. Frizzell, Joseph A. Dos Santos

"Conventional belt conveyors offer an economical method for transporting materials at inclines approaching 18 degrees. Sandwich belt conveyors may be used to transport materials at high angles, to 90 degrees, while maintaining the most positive features of conventional conveyors, that is, (1) proven conventional conveyor components. (2) high-speed operation, (3) high-single lifts, (4) continuous cleaning of the smooth surf aced belts, and (5) easy, quick repair by hot or cold vulcanizing. The present discussion deals with the evolution and development of sandwich belt conveyors to satisfy the operational requirements of the open-pit mining and materials-handling industries.A look at the limitation s of conventional shallow angle conveyors reveals the conveying angle at which a cover belt is needed. The relationship between conveying angle and hugging pressure by the cover belt is developed mathematically. A study of past and current developments reveals that the Loop Belt and Beltavator are significant advances in the state-of -the- art. The vertical radius of curvature constraints are discussed in detail and the constraint equations are developed. Criteria for future development is established as a basis for evolutionary developments in sandwich belt high-angle conveyors. The use of intermediate drives in sandwich belt high-angle conveyors is investigated.IntroductionIn connection with U.S. Bureau of Mines funded–study relating to continuous haulage from deep open-pit mines, the authors had occasion to study extensively, the use of high-angle conveyors as a means of hauling mine products continuously from the pit while maintaining optimum mine slopes to minimize total excavation. The many possible high-angle conveying methods investigated included skip hoists, bucket ladders, pocket belts, fin belts, cleated belts, sandwich belts, pipe belts, screw conveyors, slurry pipe lines, and others. The sandwich belt high-angle conveyor appeared to be the most operationally-appropriate and economical solution for the mining industry. The present paper presents the theory, historical development, state-of-the-art, and evolutionary developments in sandwich belt high-angle conveyors."

Jan 1, 1983

By Robert Stefanko

This report abstracts project work performed for the USBM Grant No. GO-133077 during the period 19 June 1973 to 15 October 1974. Five reports have been separately produced and are as follows: 1. Mine Electrical Systems Evaluation - Cable Splicing, 2. Mine Electrical Systems Evaluation - Explosion-Proofing of Mine Containers, 3. Mine Electrical Systems Evaluation - Transient Analysis, 4. Mine Electrical Systems Evaluation - Mine Power System Performance, and 5. Mine Electrical Systems Evaluation - Model Coal Mine Electrical System Specifications. Abstracts of each comprise the balance of this executive summary, and 50 copies of each volume have been forwarded to the USBM under the terms of the grant agreement.

Jan 1, 1974

By David Hurth

JOHN HAMRIC: Our next topic leader is David Huth, superintendent of sulfuric power generation, DAP, and shipping for IMC-Agrico, Nichols Plant, Mulberry, Florida. With a title like that it's no wonder he believes in empowerment. His topic today is "The Triumphs and Pitfalls of Using Empowerment Techniques." DAVID HUTH: Empowerment and its benefits are a desirable alternative to the traditional management structure. The difference between the two is the amount of decision- making authority and responsibility given to individuals by a supervisor. Just what is empowerment and how does it work? Empowerment is relinquishing to individuals the authority and responsibility to make daily decisions. Can everyone be empowered? What if they make a wrong decision? Will I empower myself out of a job? These are questions that all managers have when they hear the word empowerment. In today's fast-paced and high-pressure business environment, the old way of managing people must be replaced with a new approach. No longer can we, as managers, make all the decisions. The increased work loads due to downsizing, consolidation, and synergies have stretched us too thin. What about our employees? How can we motivate them into the high-performance teams that our companies are demanding? What possibly could satisfy both these issues? The solution to these problems can be solved with the power of employee empowerment. Employee empowerment will not only lessen the load on managers but will build teamwork, motivation, and pride into the employees who work for the managers who use it. American business was rudely awakened in the early 1980s when the Japanese companies not only caught up to American companies but literally flew by them. America was fat, dumb, and happy after World War II. Why wouldn't they be? They had all the factories. Everyone else had to rebuild. So for 40 years American business lounged in the limelight of very little true competition. But times change. Unfortunately, American business did not. Now the cry to perform in the new global economy has come down from the corporate boardrooms. Down through the ranks it has been felt. Guess who is supposed to make it work? But where are all those people who are going to make this rejuvenation and corporate renaissance possible? Many of them are gone-lost in downsizing, synergies, and rightsizings

Jan 1, 1998

By Edgar Schweitzer

The original Dorrance breaker of the Lehigh Valley Coal Co. was erected in 1883. The coal beds were clean and dry, consequently a dry preparation system was used, consisting of revolving cylindrical screens for sizing and hand-picking, to remove the few impurities from the run of mine coal. The picking or cleaning room contained long parallel rows of chutes with seats mounted on them, for the use of the breaker boy, who bent over the chute and picked out the refuse material from the coal as it gravitated down the chute. The introduction of dry mechanical pickers, of, the sliding frictional type, in the early nineties lessened the number of boys, but hand-cleaning on the coal and refuse discharge ends of the mechanical picker was necessary. The Pardee spiral pickers, which were brought out about 1900, were better than the gravity pickers and gradually replaced them. In 1912 the breaker was entirely remodeled, although the original frame was retained. The revolving screens were replaced by shaking screens, and Pardee spirals were installed on all sizes of coal from egg to pea coal, inclusive. Hand-picking still was necessary on the coal and refuse ends of the spirals, although the changes did result in a reduction of the former breaker force. As mining advanced, and the thick clean bed became exhausted, it was necessary to mine veins containing a high percentage of impurities, which complicated the preparation problem. The most serious difficulty was the increase in the quantity of damp or wet run of mine, which could not be fully cleaned on the spirals. When this quantity exceeded approximately 5 per cent. of the feed, it was necessary to send the excess of the wet coal to the company's Prospect colliery for wet washing. This plan worked well for a time, but as the amount approached 15 per cent., with the prospect of a further increase, the company considered the building of a wet-washing plant. The Dorrance breaker was the only dry-cleaning plant operated by the company. At the seventeen other collieries, wet washing was employed, and jigs, both plunger and pan, were used. All the practical methods used in the anthracite fields were investigated, and it was finally decided to adopt the Rheolaveur system. The decision was due largely to the experience gained from the the operation of a Rheo-

Jan 1, 1931

By Siyabonga Malevu

Chemical Initiatives? Umbogintwini plant is the production facility of Chemical Initiatives? business. Umbogintwini?s J Plant manufactures sulphuric acid. The plant was designed and built by Simon Carves, and was commissioned in 1974. The plant was designed to produce 500 tons/day of Sulphuric acid (H2SO4) at maximum rates. The Sulphuric acid manufacturing is through the famous contact process whereby liquid Sulphur is injected through dried air in a burner operating at 1000 °C to form sulphur dioxide (10.5% SO2). The SO2 gas is then cooled in waste heat boiler no.1 before being fed to a four pass converter which provides 99.5% SO2 conversion to sulphur trioxide (SO3). The SO3 gas is the absorbed by 98.5% H2SO4 through the inter-pass & final tower to make more concentrated acid and dilute it with water back to 98.5% H2SO4 in acid pump tanks and dispatched to storage tanks. The manufactured Sulphuric acid is supplied to a variety of industrial manufacturing customers includes Pulp & Paper industry, Mining industry, Chemical manufacturing industry etc. During the 1st quarter of the year 2007, Chemical Initiatives undertook a study to up rate the sulphuric acid plant output by 10% (i.e. from 500 tpd to 550 tpd).

Jan 1, 2009

By Horacio Reeves

Las maquinarias son elementos importantes en el proceso de minería de tajo abierto -en tanto optimizan el rendimiento del trabajo y de los operarios. Sin embargo, su contínuo uso conlleva riesgos ocupacionales en el trabajador como la exposición a vibraciones de cuerpo entero en el caso de equipos pesados. En ese sentido, el presente texto compara los niveles de vibración en los equipos pesados que operan en Antamina con el estándar europeo: Directiva 2002/44/CE, así como los efectos de este en los operarios.

Sep 12, 2005

By D Morton, G Wallace

"Evolution Mining is the sole owner of the Mt Rawdon open cut operation, located 75 km south-west of Bundaberg in Queensland, Australia (Figure 1). It is a massive, volcanically hosted, low-grade gold deposit that exhibits excellent characteristics conducive to low cost mining and treatment.In 2014, Mt Rawdon began investigating initiatives to deliver higher mill throughputs without any significant capital expenditure or modifications to the existing processing plant. Various studies have shown throughput increases are possible by applying more blast energy, essentially by reducing feed size through blasting and leaving less work for the comminution circuits (Brent et al, 2013; Ziemski, 2011; Workman and Eloranta, 2003).Given that 53 per cent of energy used on a mine site is consumed by the comminution circuit, with only two per cent being consumed by drill and blast (Smith, 2013), it makes logical sense for a mining operation to align their drill and blast with their processing plant. The term commonly used when exploring this relationship is a ‘Mine to Mill’ program.Over nearly 12 months, various blasting options and Mine to Mill methodologies were tested at Mt Rawdon. Throughout the journey, it was abundantly clear that the Mine to Mill initiative is not as simple as making one technical or physical change and expecting an improvement. Rather, true sustainable improvements demand a paradigm shift across both the mining and processing cultures, where all departments are aligned and working towards the one outcome. This true overarching Mine to Mill mentality, enabled by Vistis™ 250 high energy bulk explosive, ultimately led to a sustained increase in throughput and profitability of the Mt Rawdon operation.Citation:Wallace, G and Morton, D, 2016. High Energy Bulk Explosives and Mine to Mill Focus – the Mt Rawdon Story, in Proceedings Ninth AusIMM Open Pit Operators' Conference 2016, pp 60–69 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Nov 15, 2016

"Copper was first made in Butte by the use of iron for its precipitation from mine water in 1890. In consequence of a fire breaking out in the St. Lawrence mine of the Anaconda Copper Mining Company in November, 1889, a large quantity of water was poured into the workings, with the intention of flooding the mine and extinguishing the fire. This proved to be impracticable, but this water, on being pumped to the surface, was found to be high in copper sulphate,—tradition says 75/100 of 1 per cent. The Anaconda Copper Mining Company gave Wm. Ledford a lease on this water. He first (lug holes into the ground, filled them with scrap iron and allowed the water to flow through them. Later he built an open-top flume which he partially filled with iron and passed the water through the by the iron precipitation method. An assay in- the year 1890 from Gagnon mine water, showed .0016 per cent or 28 lbs. copper per day. The mine was then opened to the 1,000 level.None of the mine waters encountered in the solid rock in the mines of Butte contained copper in sufficient quantity to produce the metal profitably by the iron precipitation method. An assay in the year 1890 from Gagnon mine water, showed .0016 per cent or 28 lbs. copper per day. The mine was then opened to the 1,000 level."

Jan 1, 1913

By J. Philip Bromberg

The 1977 Clean Air Act Amendments will have a large effect on the coal-fired segment of the electric utility industry. Since electric power generation constitutes by far the largest single use for coal, this legislation has the potential to greatly affect future patterns of coal utilization in the U.S.A. The inability to depend exclusively upon low sulfur coal as an exclusive mode of compliance with New Source Performance Standards may greatly lessen projected demands for low sulfur coal by eastern utility boilers. The requirements of the legislation is discussed with particular reference to the needs of the electric generating industry, along with the technologies available for complying with the Act.

Jan 1, 1978

By Y. Luo

A PC based computer model has been developed by the authors for predicting the surface subsidence due to underground coal mining. Its reliability, comprehensiveness and user friendliness demonstrate that it is a good tool for the mine operators, government agencies and scientific researchers alike.

Jan 1, 1989

By Ning Zhang, Yan Chen, Qikang Yi, Linjian Ma, Guoan Wang

Laboratory tests were performed to explore the effects of frequency on the deformation property of rock salt subjected to cyclic loading under confining stress condition. A two-stage (transient and steady) evolution law of axial cumulative strain was obtained through cyclic stress-strain curves complied from the loci of minimum load of each cycle. The unloading modulus decreases with loading cycles/time as a negative exponential function. The damage of rock salt under cyclic loading is reflected by the degradation of elastic modulus. A unified damage evolution equation considering the effects of frequency and time was established based on the experimental results. A new creep damage model for rock salt was proposed by introducing the non-stationary modular components in Burgers creep equation according to the Lemaitre equivalent strain theory. Comparative study indicates that the new model can accurately describe the creep deformation and damage evolution of rock salt under different loading frequencies. This paper provides a more reasonable model and relevant mechanical parameters for the stability analysis of compressed-air storage cavern in the injection and withdrawal durations.

Jan 1, 2015

By Carlos Magno Palacios Arbizu

La calidad total es la estrategia que busca la mejorar la productividad y eficiencia de los productos que ofrece -en tanto sean reconocidos por este valor-, de forma que genera competitividad en las organizaciones peruanas y se presenta como respuesta a nuevos enfoques de gestión surgidos ante el proceso de globalización. En este sentido, el presente trabajo analiza la forma del avance en el nuevo enfoque de gestión de las empresas mineras, para así proponer alternativas de tratamiento e implementación de un modelo basado en la Calidad Total, de manera que esté alineado dentro de un sector que tenga características propias y diferenciadas de organizaciones de otros sectores productivos.

Sep 12, 2005