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By B Leisemann, M Watkinson

Coal augering is an ideal method for recovering coal from the highwalls of open cut coalmines. Coal augering is a simple process whereby additional flights are added to the auger cutting head and auger holes are drilled at 1.9 m diameter up to 200 metres deep. Traditional monitoring was located at the mouth of the hole and if methane was encountered above two per cent, inert gas was delivered into the mouth of the hole to deplete the oxygen content at the auger cutting head below 12 per cent. The auger operator was asked the question ‘how do you know that this is the case?’ Trials were undertaken to prove that the oxygen content at the cutting head did drop below 12 per cent (the lowest limit for methane to ignite, also known as the oxygen nose point). Initial trials showed that the oxygen content in the mouth of the hole did not drop below 12 per cent and modifications were made to hold the inert gases in the mouth of the hole so that the auger flights could take this inert gas into the hole. In-hole monitoring, after completion of mining and after extracting the auger flights, showed that the atmosphere quickly returned to fresh air. In-hole monitoring was also tried during the augering process and yielded valuable results. This paper will discuss the results of the monitoring, information on the gas results obtained and the methodologies used to optimise the oxygen content at the auger face.CITATION:Watkinson, M and Leisemann, B, 2017. Inertisation of coal augering holes, in Proceedings Australian Mine Vent Conference 2017, pp 293–298 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 28, 2017

Significance of the body of iron oxide, which in part overlies as its hanging-wall the rich chalcocite ore-body at Mount Oxide, Queensland, has been variously interpreted by engineers and geologists who have inspected the deposit.Among the interpretations offered is the one that the body represents the residual of an original medium to low grade...

Jan 1, 1939

By C. A. Rowland Jr

"I. INTRODUCTIONFred C. Bond's ""Third Theory of Comminution"" (1) was published in 1952. The mathematical statement of the Third Theory is the well-known Bond Formula:where W - Kw H per short tonWl - Work IndexP - Product size in microns which 80% passesF .. Product size in microns which 80% passesWork Index, as defined by Fred Bond, "" ... is the comminution parameter which expresses the resistance of the material to crushing and grinding. Numerically, the Work Index is the KwHrs per short ton required to reduce the material from theoretically infinite feed size to 80% passing 100 microns."" (2)Work indices for grinding can be obtained tram Bond grindability tests and can be calculated from plant grinding mill operating data when power consumed per ton of ore ground, the feed size analysis and the product size analysis are known.Work indices obtained tram Bond grindability tests, having been obtained from standard and controlled laboratory procedures, are reproducible and for the sample tested are accurate. The degree of accuracy relative to plant mill operation depends upon how representative the sample is of the total mill feed.The results of the Bond closed circuit rod and ball mill grindability tests (3) are given in grams of product sized material produced per revolution of the test mill. In developing a method to evaluate plant operating data and results from his grindability test, Fred Bond developed the ""Third Theory of Comminution."" In the process formulae were developed for converting grams per revolutionobtained from grindability tests to work index.The standard feed sizes for the Bond grindability tests are:Rod Mill Test ore crushed to minus 1ll inchBall Mill Test ore crushed to minus 6 mesh (Tyler)The formulae for converting grams per revolution to work index incorporate the 80% passing sizes for the feed to and the product produced in the specific test. Therefore, accurate work indices can be obtained from Bond grindability tests when the feed size is finer than standard. To obtain accurate test results, the ratio of reduction should be greater than 6 to 1."

Jan 1, 1972

By Kathleen M. Kowalski

In emergency management, the effects of stress on the performance of emergency personnel, typically have been ignored or regarded as too enigmatic to quantify. This paper discusses the concept of Critical Incident Stress in responders to emergencies. It presents the rationale for considering stress as a significant factor in the management of emergencies. It is proposed that Critical Incident Stress Debriefing in a disaster can improve the effectiveness of response teams on site, their turnaround time on site, and post-disaster time off the job. Critical Incident Stress intervention also can mitigate potential deleterious emotional effects associated with emergency work. This paper, prepared by a U.S. Bureau of Mines researcher, offers some ideas to the mining industry in general, to mine rescue team trainers, and to developers of program simulations on the specific issue of how people, time, materials and space may be factored into a plan for emergency management. The impact of stress on emergency workers is, presented as a missing component in present emergency management models.

By Hemang Desai

A damaged outlet pipe beneath Lenihan Dam has restricted reservoir discharges, severely constraining the owner?s groundwater recharge program. The solution, a new outlet pipeline through the dam?s right abutment, includes an approximately12.2-m-deep (40-ft-deep) shaft and 618.7-m-long, 4.3-m-diameter (2,030-ft long, 14-ft-diameter) tunnel mined in Franciscan melange composed of hard blocks of rock and soft clayey matrix. Alternating road header with drill and blast operations and using steel ribs and shotcrete have proven a flexible combination for handling the variable ground conditions. Excavating the shaft and connecting it to the tunnel require lowering the reservoir for five months, during which time careful construction sequencing and use of a tunnel plug eliminate the risk of an uncontrolled discharge.

By Alexi J. Neill

"This presentation will showcase two challenging projects with deep excavation support systems in the Atlanta area where state-of-the-art instrumentation and monitoring systems were used to manage risk by confirming design performance requirements / calculations during construction. The instrumentation and monitoring system successfully reduced risk by recording real-time data on a project website while simultaneously sending email alarms to key site personnel when data exceeded pre-determined alarm thresholds. The monitoring data revealed unexpected performance at an early enough stage so that contingency plans could be engaged and remedial efforts devised in order to limit the consequences. Finite element analysis was used to model deformations, analyze the unexpected performance, and prepare theremedial design.INTRODUCTIONConstruction in densely populated urban areas is becoming more common in order to keep up with the increasing infrastructure demands of our growing population. America’s big cities continue to outpace the overall nation in population growth. The city of Atlanta, the nation’s ninth largest city based on metropolitan population, is a prime example of this. The population has grown at a rate of 6.6% between 2010 and 2013, nearly triple the overall growth rate of the United States during the same period (SustainAtlanta, 2015).As a result of increasing infrastructure demands in Atlanta, developers are now constructing larger buildings on smaller properties. In addition, developers are attempting to maximize space on their selected properties, often by designing underground parking garages to accommodate as many cars as possible on these compact sites. In some cases the selected sites are adjacent to buildings, utilities, and other existing structures. The risk associated with construction increases during underground work that requires a support of excavation system, particularly on confined sites adjacent to existing structures. There is a risk posed to people, property, and the environment that the project team should monitor when constructing in these conditions."

Jan 1, 2016

By David Chapman, Glen Frank

Due to the transport mechanics of the depositional environment, glacial soils display a very wide range of grain sizes and behavior. Several nonstandard drilling, sampling, and analytical techniques are therefore required to characterize the subsurface. The paper summarizes the geotechnical investigation for the design of a large project in glacial geology, which will include both large and small diameter pressure balance tunneling. The paper focuses on the challenges presented by the glacial environment and the techniques required to identify and characterize it for design and contract document preparation.

Jan 1, 2001

By J. F. Brune

This paper analyzes the explosion hazard resulting from the formation of methane-air mixtures in the mined-out gobs of underground longwall coal mines. Although direct examinations of the gob atmosphere are difficult due to the inaccessibility of these gobs, evidence from methane drainage practices and investigations of numerous mine explosions suggests that explosive methane zones can form within longwall gobs. Explosions and fires resulting from these methane accumulations have led to severe and fatal injuries to the miners. Most recently, this was demonstrated in the explosion of the Upper Big Branch Mine in West Virginia, where 29 miners lost their lives.The paper also reviews current research on numerical modeling of gas flows in longwall gobs and outlines how targeted injection of nitrogen into gobs can effectively reduce the volume of such explosive methane zones. The paper concludes that comprehensive monitoring of gas compositions, along the accessible fringes of the gobs along with inertization, improved ventilation schemes and further research are necessary to control this explosion hazard and make mining operations safe.

Jan 1, 2013

By Peter C. Wood

This report describes research directed toward the preparation of chemical oxygen (02) sources which exhibited improved 02 storage and reaction characteristics when compared to potassium superoxide (KO2). The initial focus of the research was the preparation of calcium superoxide (Ca(02)2) by the disproportionation of calcium peroxide diperoxyhydrate. The Ca(02)2) was characterized by chemical, thermal, and x-ray analyses. Several methods for scaling up the Ca(02)2 synthesis process were studied. Next, the reactivity of Ca(02)2 toward humidified carbon dioxide (C02) was evaluated and was compare o that of K02 under flow-test conditions approximating those existing in portable breathing apparatus. The reactivities of mixtures of K02 and Ca(02)2 or lithium peroxide towards humidified CO2 were also studied. Finally, an analysis of two commercial, K02-based, self-contained self-rescuers was conducted to determine the potential weight and volume savings which would be possible if Ca(02)2 or a mixture of K02 and Ca(02)2 were used as a replacement for K02.

Jan 1, 1983

By Baker G

The exposures resulting from development work, following on the discovery of a new shoot of hIgh grade ore at the north end of the Sardine tin mine, during 1952, have provided an unusual opportunity to study the oxidation of a stannite-rich ore. Through the kindness of C. C. Morton, Chief Government Geologist of Queensland, an exactly located suite of specimens representative of the exposures was supplied by J. and W. Reddie. This was later supplemented by a number of specimens culled from a parcel ofrepresentative ore submitted to the Melbourne Ore Dressing Laboratory for testing.The Sardine tin mine, near Ewan, Queensland, has been the outstanding producer of the Kangaroo Hills Mineral Field. Since its discovery in 1918, up to 1952 it has yielded about 1,500 tons of cassiterite concentrates, and about 85 tons of stannite concentrates. The outcrop ore averaged 35% tin oxide, but the grade declined with increasing depth, and by 1930 had fallen to 7% tin oxide. In the northern section of the mine the ore shoots show a downward passage to complex primary s.ulphide ore, containing cassiterite and abundant stannite.The orebodies occur in a series of fissures in a crushed zone about 50 ft. wide in slates and quartzites that have been intruded by granite (Connah, 1952). A quartz porphyry dyke forms the footwall of the original main lode in its southern part, being traced' from the surface to' the No. 4 level (173 ft. vertical depth), and two narrow dolerite dykes were encountered in the workings north of the main...

Jan 1, 1954

By Ruxton B. P, Rhodes J. M

Two Rb-Sr ages are discernible in data concerning the leucocratic granite which is the youngest pre-sedimentation phase of the crystalline basement complex at Rum Jungle, Northern Territory, Australia. Whole-rockdata suggest that intrusion of this unit took place at about 2400 my ago, with a probable initial ratio around o·707; whole rock-potassium feldspar tie-lines indicate redistribution of strontium at about 1800 my ago. The former age correlates with other measurements on rocks which form basement to the mantling Pine Creek Geosyncline; the latter correlates also with isotopic evidence for regional metamorphism and emplacement of some younger intrusive granites elsewhere within the geosyncline. A few K-Ar ages, from scattered localities, conform generally with the later event or events which appear to have some connection with the structural deformation clearly observable both in the complex and the surrounding metasediments. It is these younger events which appear to match the residual evidence for the earliest detectable concentration of uranium minerals in the Alligator Rivers district.

Jan 1, 1977

By M. E. Volin

The Smuggler is one of the mines in the Aspen district, located the central part of Pitkin County, Colo. It was first examined in July 1943 by C. R. Wilfloy, former mining engineer of the Bureau of Mines at Salt Lake City, Utah, in, company with the lessees, R. D. Rohlfing of Aspen and J. W. Vanderwilt of Denver. The purpose of this examination was to sample a mineralized breccia zone that appeared continuous along the contact between the Leadville and Weber formations. These preliminary samples showed that the zone contains low but significant amounts of lead and zinc and that the minerals are partly oxidized and thus not easily concentrated. The mine was examined again in May 1946 by the senior author and William Herron, one of the present lessees of the property. This examination reviewed the previous sampling and recommended investigations by the Bureau of Mines. Sampling and drilling investigations were conducted by the Bureau from October 1946 to February 1947 and again from August 1947 to April 1948. Aspen is the center of a famous mining district that produced over $102,000,000 in silver and lead ores from 1880 to 1918, when a dispute closed down the mines (fig. 1). All of the workings below the Cowenhoven tunnel in Smuggler Mountain and the lower Durant tunnel in Aspen Mountain have been flooded since that time. The Cowenhoven portal now is caved, and Smuggler Nos. 1 and 2 tunnels are the only accessible workings in Smuggler Mountain. The only operating mine is the Midnight, situated 4 miles south of town at an altitude of 9,700 feet.

Jan 1, 1950

An intensely sheared and mineralized zone occurs in the quartz dolerite greenstone (or younger greenstone) mass on the western limb of the Kalgoorlie syncline. This zone comprises the western part of the Golden Mile and has produced the greater part of the 33,000,000 oz of gold produced to date from the main mining belts. A study of the general geological and structural features suggests that the lode shear system will continue southward on a pitch similar to that of the main syncline. Although payable ore has been found recently further to the south, the expectation of large quantities extending southward from the present mining areas is problematical.INTRODUCTIONUntil the late 1930's the principal mining activities in the western lode system were centred on three major ore-shoots formed on the No. 4, No. 3 and to a lesser extent on the No. 2 lode shears (Fig. 1). With the gradual reduction of grade in depth on these main ore shoots, increasing attention was paid to the "Minor Lode" system of lode shears known to exist in the same area. A large quantity of payable ore was found on these "Minor Lodes" particularly in the central part of the mining area. In recent years more attention has been given to exploration in a southerly direction.ROCK TYPES AND STRUCTURESThe western system occurs on the western flank of a dragfolded, south pitching syncline. The rock succession consists of Black Flag sediments overlying the younger greenstone horizon which overlies the fine grained older greenstone horizon. The axis of the syncline is regarded as a tight infold of the overlying Black Flag sediments. This infold has been faulted and intruded by albite porphyry resulting in the formation of a composite body of slates...

Jan 1, 1964

By M. B. Boyer, C. H. Herty, F. A. Hartgen, G. L. Frear

"DEFINITION OF VISCOSITYViscosity has been defined as the resistance experienced by one portion of a liquid moving over another portion, such as one molecular plane moving over an adjacent plane. A measure of viscosity is the force required to keep one plane in motion at Unit velocity, the other plane being considered stationary. Figure 1 illustrates the general idea that the surface friction between two adjacent areas will be greater the larger the molecules. Therefore it may be assumed that viscosity will be increased by molecular association or agglomeration, and likewise dissociation rill decrease viscosity. According to Maxwell (1)6 the unit of viscosity, the poise, is the tangential force per square centimeter of area of either of two horizontal planes 1 centimeter apart, one of which is fixed while the other moves with unit velocity, the space between being filled with viscous liquid of unit viscosity.The need for a satisfactory apparatus and experimental procedure for the determination of viscosity of high-melting materials at temperatures corresponding to those in pig-iron and steel making has been recognized during the past few decades. The condition of the slag during the smelting and refining periods in the iron- and steel-making processes exerts an important influence on the metal product obtained, this slag condition really meaning the state of viscosity or, vice versa, fluidity, which the slag attains under certain conditions."

Jun 1, 1934

By James V. Errico

On October 1, 1993 the regulations for assessing and cleaning up contaminated soil and groundwater in the Commonwealth of Massachusetts were revised. These new regulations, known as the Massachusetts Contingency Plan (MCP) 310 CMR 40.0000, were developed to keep routine releases out of the regulatory system and rely on private parties to handle most releases without Department of Environmental Protection (DEP) oversight. An integral part of the new MCP is the Licensed Site Professional (LSP). An LSP is required to handle activities and render opinions once a site enters the MCP. These regulations must be adhered to where ever a release has occurred, including construction sites. A brief overview of the new MCP is given below; see attached MCP Flowchart for graphical summary. Entering the MCP Process A release of oil or hazardous material (OHM) to the soil or groundwater above applicable reportable quantities (RQ's) or reportable concentrations (RC's) will require notification to the DEP and compliance with applicable provisions of the MCP. RQ's and RC's are listed in the MCP (310 CMR 40.1600) for most compounds that are typically encountered. For each compound there are two RC's for soil (S-1 and S-2) and two for groundwater (GW-1 and GW-2). The S-1 and GW-1 RC's apply to sites that are environmentally more sensitive, as a result they are lower than the S-2 and GW-2 RC's.

Jan 1, 1994

By P D. Katsabanis

According to Persson(1) steady state detonation along a cylindrical charge can be regarded as a self propagating process in which the axial compressive effect of the shock front discontinuity changes the state of the explosive so that exothermic reaction sets in with the requisite velocity.

Jan 1, 1990

By A. C. Apling, N. B. Barrett

Roadstone production requires the generation of non-flaky material, as outlined in British Standard 812 section 105.1; with respect to this criterion, a mathematical model of a cone crusher must be able to predict the flakiness index of a particular size range as determined by the relationship between thickness and nominal size. The Whiten cone crusher model utilises breakage and classification functions to predict a product particle size distribution only, so a shape function has been proposed that is based on a phenomenological approach, taking into account the transfer between flaky and non-flaky material at each stage of breakage. The results of laboratory tests to determine material breakage characteristics and of examination of pilot-scale test products illustrate the method's potential

Apr 1, 1995

By E. H. Burroughs

This bulletin is the sixth in the series of petroleum bibliographies published by the Bureau of Mines, Bulletins 149, 165, 180, 189, and 216 being compilations for the years 1915, 1916, 1917, 1918, and 1919- 1920, respectively. In this bulletin the same general plan has been followed in arranging the references, but one or two additions have been made in the classification.

Jan 1, 1921

Northern Iron Ltd (NIL) is an Australian listed company that recently brought the historic Sydvaranger open pit Magnetite Mine (the Project) in Northern Norway successfully back into production. NIL made the decision to operate the Project on an owner mining basis, due to limited large scale mining expertise amongst Norwegian mining contractors, a long mine life, a limited range in planned mining rate and to minimise costs. As a new mine operator in a country where labour practices are strictly regulated, there was the desire to reduce the risk associated employing and managing skilled personnel. This was achieved by coupling the purchase of the required mining equipment from the original equipment manufacturer's (OEM) regional dealers with OEM supported Maintenance and Repair Contracts (MARC). This paper examines the process that was followed to implement an owner mining operation in a short time frame; approximately 12 months from the initial requests for quotation to actual delivery of mining equipment to site, and some of the challenges faced. By following a formal and well-tested process, not only was the implementation achieved in the set time frame, but significant value was added through the cost savings achieved in the equipment purchase price and MARC rates that were negotiated through this process.

May 1, 2010

By John Babcock, Gregory Poole, Ron Hudson

In January 2007, Fultondale Alabama opened a new elementary school. Site work at the old school location included blasting activities and the old school building was scheduled for demolition. With help from Apache Construction, blasting was scheduled to be performed in close proximity to the old school building prior to the demolition. Arrangements were made to perform extensive monitoring on the old school building during the blasting activities. The monitoring plan for the project included: • Pre and post blast inspections were performed on the structure; • Conventional crack monitors were installed at 22 locations throughout the structure; • Digital displacement monitors were installed at 6 locations on the structure; and • Seismographs were used to monitor structure vibration at 6 locations and ground vibrations at 9 locations. Blasting activities were allowed to produce vibration levels well above the safe levels established by the U.S. Bureau of Mines (USBM). Vibration levels up to 7.44 in/sec were recorded with no damage noted. Permanent deformation was recorded on vibration levels of 9.68 and above. Not only did this project reinforce previous studies which indicate that concrete block walls can withstand vibration levels well above 2.0 in/sec, this study was also a good example of employing new technology to help determine if/when damage occurs on a specific structure.

Jan 1, 2009