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By Grant R. Brown

This report presents the results of a study examining the relationship between supervisor characteristics and performance in underground coal mines, The specific objectives of the research include; document tasks performed by first-line supervisors during a normal shift; explain why supervisors carry out their duties as they do: identify salient characteristics of effective first-line supervisors; and formulate criteria for selecting and developing candidate supervisors. To accomplish the study objectives, on-site observation and data collection was carried out at 13 underground mines in Illinois, Ohio, and Pennsylvania. One hundred thirty-eight first-line supervisors were observed during a full work-shift and discussions with the supervisors and the mine superintendent were held during the course of the visit. The observational data from the study provide a detailed description of what supervisors to during their shift. The report begins with an introduction discussing the problem being studied and objectives of the research. The literature related to supervisor selection is then reviewed. The following section describes the research design including data collection procedures and statistical methodology used in the study. The next sections present the analysis of mine, section, crew, and supervisor characteristics. The report concludes with a discussion of the results of the study and recommendations concerning supervisor selection and development.

Jan 1, 1987

By Kimberlee Falkenstein, Volha Kibitkina, Jessica Steeves

A series of experiments were conducted to obtain site specific constants for the vibration produced by a single charge and by more charges detonating in sequence, using short delay intervals. All charges were placed in relatively long boreholes in granite without a free face other than the ground surface. The boreholes were filled with water to provide good coupling with the rock and to provide identical confinement for all the blasts. Vibrations were recorded close to each blast in the vertical direction by uniaxial high frequency geophones and far field using a triaxial geophone.

Jan 1, 2013

Crocidolite deposits in the Hamersley Ranges, NW. of Western Australia, occur over a length of 180 miles and a width of 20' to 30 miles. Their stratigraphic environment and mineralogy is comparable to that of similar deposits of the Cape Belt, South Africa. It is probable that the known exposures' represent only a small portion of the total extent.Current production is wholly by Australian Blue Asbestos Pty. Ltd. at Wittenoom Gorge and has been in the order of 1,2,000 to 14,000 long t.p.a over the past six years.INTRODUCTIONThe Hamersley Ranges are located in the NW. Division of Western Australia and extend, approximately, from latitudes 21° 30' to 23°S and longitudes 117° to 1200 E. Their mean height above sea level is 2,000 ft, and they rise from 600 to 800 ft above the general level of the tableland which extends SE. from the coastal town of Roebourne.Mt. Bruce, the highest peak, is 4,024 ft above sea level. The ranges are intersected by numerous north-flowing streams, which are dry during the greater part of the year. These streams have carved deep gorges, and it is in these that the principal deposits of crocidolite outcrop.The presence of the mineral was first recorded in 1917, but the deposits remained untouched until 1937 when strong market demand for crocidolite resulted in considerable prospecting and mining activity, particularly in Yampire, Wittenoom and Dale's Gorges. It was established also that the blue asbestos belt extended from Willi Wolli Springs NW. to Millstream station, Le., over a length of 180 miles and a width of 20 to 30 miles. A number of attempts were made to develop and treat the Yampire and Wittenoom...

Jan 1, 1964

In the spring of 1944 the Congress passed Public Law 290 (58 Stat. 190, 30 U. S. C. Sec. 321) "authorizing the construction and operation of demonstration plants to produce synthetic liquid fuels from coal, oil shales, agricultural and forestry products, and other substances, in order to aid the prosecution of the war, to conserve and increase the oil resources of the Nation, and for other purposes." Section 2 reads: "In order to carry out the purpose of this act, the Secretary of the Interior is authorized- (a) to conduct laboratory research and development work, and, with pilot plants and semi-works plants, to make careful process engineering studies, along with structural engineering studies, in order to ascertain lowest investment and operating costs necessary to determine the best demonstration plant designs and conditions of operation;

Jan 1, 1948

By Z. H. Zhou

It is difficult to remove cadmium from raw indium using only electrolytic refining because their standard potentials are similar. In this paper, physical and chemical methods were used to remove Cd from raw indium. Indium metal is vacuum refined for two hours at 400°C with a vacuum pressure of 20 Pa. In this process, 99.70% of the Cd can be removed. The removal rate of Cd reaches 90% to 95% when indium is further smelted for 10 minutes in a 20% glycerin solution of KI and I2 at 180°C. When pre-indium is electrolytic refined in an In2(SO4)3-H2SO4 system, in which the indium content is 80 to 100 g/L, the pH is 2.0-3.0 and the current density is 80 to 100 A/m2, the contents of the impurities decrease and the purity of the indium product reaches 99.99%.

Jan 1, 2007

By Marcello M. Veiga

Informal gold mining operations in the Amazon emit about 100 tonnes of mercury annually because of poor amalgamation practice. Lack of information and the complexity of mercury transformations hinder effective action to prevent such pollution and/or monitor its extent. In the past, mathematical equations have been formulated to deal with the correlation of natural variables and mercury in biota but often, the error range is too great to provide useful models. Projection of physico-chemical variations in an environment subjected to mercury emissions onto the extent of bioaccumulation is fraught with many uncertainties and unknowns such as internal correlations between variables and the site-specific nature of biota contamination. Often assumptions about closed systems are invalid when applied to natural environments. This work presents a heuristic approach to this problem in which amalgamation methods and natural variables are dealt with using an IF-THEN rule-based system that concludes about levels of emission and risk of bioaccumulation. The system is able to handle uncertain or vague data and yet still provide useful output. Belief in mercury oxidation or dangerous conditions are examined using Fuzzy Logic techniques and Inference Equations. These belief levels are derived from thermodynamic equilibrium data together with field observations of natural variables. This procedure can reduce the need for sophisticated analytical equipment and can provide information and diagnosis to non-technical people.

Jan 1, 1994

Iron ore in the Middleback Range area has a density and susceptibility contrast with adjacent rocks, and gravity and magnetic methods are applicable to exploration for it. The gravity method is satisfactory whether the ore mineral is hematite, magnetite, or limonite; the magnetic method is suitable for detecting ores which contain magnetite, such as some hematite ore, magnetite ore, and possible ore in the form of magnetite-bearing schists. jaspilites, and carbonate rocks.Geophysical exploration began in 1948 and is still in progress. The methods which have been used are aeromagnetic (83 per cent), ground magnetic (13 per cent), gravity (3 per cent), and others (1 per cent). Ground magnetic surveys have been made wherever aeromagnetic surveys recorded large anomalies. The gravity method is being used to investigate those parts of the area considered most favourable for ore occurrence.Qualitative and quantitative interpretation of the geophysical data has been made and the rocks causing selected anomalies tested by bores.Magnetite in the Middleback Group rocks produces the major magnetic anomalies in the area. The average magnetite content of magnetite-jaspilite, which is the commonest rock type, is 33 per cent by weight and that of magnetite-carbonate at the Iron Duke-Iron Duchess is 50 per cent. These rock types also contain hematite and the average total iron content of the former is 35 per cent and of the latter 50 per cent.INTRODUCTIONThe geology and iron ore resources of the Middleback Range area were described by Miles (1954). Since 1954, much drilling, mapping, and quarrying has been done but there is no published report of this work.The rocks which constitute the Middleback Range, Camel Hill-Cooyerdoo line, Katunga Hill-Iron Knob, and Ash Range (Fig. 1) belong to the Middleback Group of Middle Precambrian or late Archaean age. Most outcrops of the Group are jaspilites, formerly called banded hematite (or magnetite) quartzite. The high grade hematite deposits...

Jan 1, 1964

By Keith Jones, Michael Francis

Contract 240 of the Channel Tunnel Rail Link comprises construction of twin4.7 km long running tunnels through a densely populated area of East London. The tunnels were constructed by EPBM in Sands and Sandy Clays, passing 4.4 m below the existing London Underground tunnels, and at depths of 20–30m below ground level beneath the Great Eastern railway lines into London Liverpool Street and a series of railway bridges and hundreds of buildings. This paper describes how the project team managed the challenges relating to the issue of settlement: mitigating settlement effects, prioritising the structures to be assessed, controlling resource expenditure by incentives and flexible response to urgent work relating to unforeseen events such as ground collapse and discovery of unusual structures.

Jan 1, 2005

In spite of the many contributions that have been made to our knowledge of the creep properties of polycrystalline lead, the precise influence of various factors on these properties is not yet fully understood. Indeed, the position is such that several important points in connection with the creep of lead are a matter of controversy. This has been brought about largely by the fact that, in the case of lead, the changes that are produced in the creep behaviour by slight variations of such factors as the purity, grain sizeand previous treatment are out of all proportion to the magnitude of these variations.In order to study the fundamental properties of lead as related to creep, and so gain a more enlightened perspective with which to consider the creep of lead in general, the work that is described in a series of papers, of which the present paper is the third part, has been carried out. It deals with lead in the form of single crystals.It has been shown (1) - (3) that the grain boundaries as well as the actual grains play a part in the creep of polycrystalline lead. The present work, by eliminating grain boundaries, enables the. contribution of the grains themselves to the process of creep, in other words, crystalline creep, to be studied effectively.This object was, possibly, the major one in this work.

Jan 1, 1940

By Thomas Gregor, Brian Garrod

As the popularity of precast concrete segmental linings for tunnels is growing in North America, some problems related to grouting of, and near, these linings are starting to appear. The installation of a segmental lining behind a TBM requires that the annular space around the lining be quickly filled with grout to prevent collapse of the ground. In practice, the filling of the annulus is frequently delayed and takes place a distance behind the machine typically via grout ports centrally located in the segments. If partial collapse of the annulus has occurred, it may become necessary to use higher grouting pressures in an attempt to distribute the grout. There have been several occasions where these increased pressures have caused damage to the tunnel linings. Similarly, compaction grouting adjacent to a tunnel lining can cause damage. This paper quantifies the effects of such grouting on a typical precast lining.

Jan 1, 2005

By J. R. Allsup

Air pollutants in exhaust gas produced from LP-gas (propane) were studied using both laboratory engines and vehicles. The objective of the study was to evaluate engine parameters relating to the advantageous use of propane as a low-pollution fuel. Some comparisons are made between gasoline, natural gas, and propane. Results show that engines can operate over a wider range of A/F with minimum carbon monoxide and hydrocarbon emission when using propane than when using gasoline. Mixture enrichment using propane is unnecessary during cold starts, thereby eliminating the emission penalty during warmup. Carbon monoxide and hydrocarbon emission using propane are unaffected by ambient temperature. The photochemical reactivity of hydrocarbon emission is considerably lower with propane than with gasoline.

Jan 1, 1972

By Gabriel S. Esterhuizen

A survey of pillar conditions was carried out at 21 operating limestone mines that use the room-and-pillar method. The surveyed pillars were all located in rock that was classified as ?Good? to ?Very Good? using the RMR rock mass classification system. The average pillar width was 14.5m and the width to height ratio varied between 0.53 and 3.52. Pillar conditions were rated using a visual rating system that accounts for the effect of geological structures as well as stress related fracturing. Nine cases of pillar instability were recorded. Pillar instabilities were typically limited to individual pillars or small groups of pillars within an otherwise stable layout. Local geological structures such as inclined discontinuities or weak bedding planes contributed to instability in seven of nine cases that were observed. Elevated pillar stresses contributed to instability in the two remaining cases. All the unstable pillars observed had width-to-height ratios of less than 1.5. It is concluded that pillar instability is most likely to be caused by unfavorable geological structures in pillars with width to height ratios of less than 1.5. Stress related instability such as rib spalling becomes more prevalent when the average pillar stress approaches approximately 20 MPa.

Jan 1, 2006

By Gary Brendel

India produces about 70 Mt/a (77million stpy) of coal ash (fly ash and bottom ash) from burning about 200 Mt/a (220 million stpy) of coal for electric power generation. The average ash content is 35%. In contrast, the United States produces about 70 Mt/a (77 million stpy) of coal ash from burning 800 Mt/a (880million stpy) of coal for power generation. Its average ash content is less than 10%. In 1998, GAI Consultants Inc.(GAI) embarked on a federally funded, multiyear project to assist the government of India in solving its growing coal-ash management problem.

Jan 1, 1999

By David Bendersky

The principal objectives of this study are to: (1) survey electrical practices in metal and non-metal mines, (2) survey electrical practices in metal and non-metal mills, (3) clarify the federal regulations governing electrical practices in metal and non-metal mines/mills, (4) analyze electrical accidents, and (5) make recommendations aimed at improvement of the safety of electrical practices in metal and non-metal mines. Information was obtained from literature searches, accident reports, visits to 27 mines and 12 mills, and discussions with knowledgeable industry and government people. The various electrical power systems and practices at the mines and mills visited are described. Similarities and differences based on the type of mining and the minerals being mined or milled are presented. The federal regulations governing metal/non-metal mine/mill electrical practices (Code of Federal Regulations, Title 30, Sections 55.12, 56.12, and 57.12) are presented and discussed. Explanations of each regulation are provided in an appendix. The attitudes of mine/mill operators towards the federal regulations are described. An analysis of the electrical accidents in metal/non-metal mines and mills during the period 1972-1978 is presented. Recommendations, including specific research and development activities, aimed at improvement of electrical safety in metal/non-metal mines are submitted.

Jan 1, 1980

By J. M. Benson

Titanium is an exciting structural material that can offer significant strength-to-weight advantages over currently used alloys. However, its Achilles? heel is its costly, energy-intensive production process that effectively eliminates it from competing with aluminium and high-strength steels, apart from critical applications where titanium forms only a small component of the total cost. Current attempts are being made to reduce the cost of titanium products and these recognize the importance of minimizing the costs over the total production chain. Powder metallurgy (PM) technologies play a crucial role within this, as the output of the existing and potential primary metal production methods is in the form of sponge or powder. By using PM, costly remelting and forming operations can then be avoided, except in the manufacture of large components. Metal injection moulding (MIM) is an effective process for producing complex net-shape components in large volumes from metal powders. Nevertheless, the commercial use of titanium powders in this process is still in its infancy. The only major supplier of feedstock utilizes a polyacetal-based binder. This gives good green strength but requires a catalytic nitric acid process to remove most of the binder prior to thermal treatment. As this involves additional and expensive equipment and is a potentially hazardous process, there is interest in finding an alternative binder system that can be debound either purely thermally or that involves a less hazardous, more environmentally friendly solvent. This paper describes the use of capillary rheometry to characterize the influence of temperature and shear rates on the flow behaviour of potential binder systems for titanium MIM feedstock. Keywords Titanium, metal injection moulding, capillary rheology, feedstocks, powder loading.

Jan 1, 2011

The theme of the 2012 North American Tunneling conference (NAT) was ?Tunneling: Driving Value.? This theme best reflects where the tunneling and underground construction industry is to-day. Major advances that have been made in technologies have provided tremendous improvements in productivity, which, in turn, have allowed the industry to deliver more cost-effective and less disruptive solutions to the nation?s infrastructure needs. Despite a weak economy, domestically and globally, cities and states continue to spend billions on infrastructure improvements. For the underground construction industry, that means more transportation and water, wastewater, storm water projects and other underground structures. And, for each project completed, underground construction and tunneling technology grows. The NAT conference, put on by the Underground Construction Association (UCA) of SME, provides an outlet for technology transfers among professionals. This year?s conference, held in Indianapolis, IN June 24-27, attracted 918 attendees, up from 803 at the last NAT in 2010. The accompanying exhibit also featured 116 exhibitors occupying 140 booths. That was up from 108 booths in 2010. So, the meeting continues to grow as underground construction professionals throughout the world seek to learn from their peers.

Jan 1, 2012

By K. S. Rao, R. P. Tiwari, V. K. Shrivastava

ABSRACT: In this paper numerical simulation of jointed block mass behaviour obtained in an experimental study has been presented. Singh et al. (2002) conducted extensive tests on the jointed model materials with several joint configurations. The results of this experimental study were used to validate the strength behaviour of numerical block mass model developed using professionally available software. This software basically contains different kinds of material models. From the results of numerical simulation the existence of strength anisotropy was observed. The strength anisotropy so obtained has been compared with the experimental values reported by Singh et al. (2002). The anisotropic curves in both cases are U-shaped with flat base. They show good agreement in sliding mode of failure zone in which inclination ß (= 90° - ?) of joint set-I lie between 20° to 40° for all cases of interlocking. ZUSAMMENFASSUNG: In dieser numerischen Papiersimulation des verbundenen Blockmasse Verhaltens, das in einer experimentellen Studie erhalten wird, ist dargestellt worden. Singh et al. (2002) leiteten umfangreiche Tests auf den verbundenen vorbildlichen Materialien mit einigen gemeinsamen Konfigurationen. Die Resultate dieser experimentellen Studie wurden verwendet, um das Stärke Verhalten des numerischen Blockmasse Modells zu validieren, das mit professionell vorhandener Software entwickelt wurde. Diese Software enthält im Allgemeinen unterschiedliche Arten der materiellen Modelle. Von den Resultaten der numerischen Simulation wurde das Bestehen von Stärke Anisotrophie beobachtet. Die Stärke Anisotrophie also erreicht ist mit den experimentellen Werten verglichen worden, die von Singh et al. (2002) berichtet werden. Die anisotropen Kurven in beiden Fällen sind mit flacher Unterseite u-förmig. Sie zeigen gute Vereinbarung in gleitender Erscheinungsform des Ausfalls Zone, in der Neigung ß (= 90° - ?) von der Verbindung stellenSie Lüge zwischen 20° auf 40° für alle Fälle vom Ineinandergreifen ein. RESUME: Dans cette simulation numérique de papier du comportement joint de la masse de bloc obtenu en étude expérimentale a été présenté. Singh et autres (2002) ont effectué les essais étendus sur les matériaux modèles joints avec plusieurs configurations communes. Les résultats de cette étude expérimentale ont été employés pour valider le comportement de résistance du modèle numérique de la masse de bloc développé en utilisant le logiciel professionnellement disponible. Ce logiciel contient fondamentalement différents genres de modèles matériels. Des résultats de la simulation numérique on a observé l'existence de l'anisotropie de force. L'anisotropie de force ainsi obtenu a été comparée aux valeurs expérimentales rapportées par Singh et autres (2002). Les courbes anisotropes dans les deux cas sont en U avec la base plate. Elles montrent la bonne concordance dans le mode coulissant de la zone d'échec en lequel la inclination ß (= 90° - ?) du joint placez-Je le mensonge entre 20° à 40° pour tous les cas d'enclencher.

Jan 1, 2003

By Daniel Mallette, Richard Goodridge, C M. Lownds

Despite a world of mobile devices that has many of us taking the ability to communicate wirelessly for granted, an in-hole wireless initiation system was thought to be not viable. The known and common wireless communication techniques are not suited to this application. To overcome this, we have developed cutting edge technology to communicate to our initiating devices more than 1km through solid rock.

Jan 1, 2016

By Lon Santis, Dale Ramsey

The use of aircraft to support blasting operations in mines, quarries and construction sites goes back to the early days of aviation. Invaluable at times, aircraft use has been limited by cost, the unpredictability of weather impacts and other factors. Recently several technologies have matured to open up a new way to acquire aerial data with unmanned aircraft systems (UAS), commonly called drones. Equally important, the U.S. Federal Aviation Administration has recently implemented an exemption process and rulemaking to implement the commercial use of UAS into the United States’ National Airspace. The skies are opening for many applications of UAS. The most notable may be photogrammetry, which is the science of making measurements from photographs, especially for determining the exact positions of surface points.

Jan 1, 2016

THE method depends upon:--1. The position of the mill.2. The space available for stacking the residue.3. The nature of the residue as discharged from the mill.4. The value of the residue for re-treatment.5. The requirement of the residue for underground filling.Originally the conditions in this district varied mainly in the position of the mill, some mills having an elevated site with plenty of dumping space for the time being, whilst others had a flat site, and very little dumping space near at hand; but in most cases the residue discharged was in the form of filter-press cakes, suitable for conveying on belts, or in trucks, and stacking in a high clump; and, while a portion of the residue was used for underground filling, the dump was regarded as a valuable asset, to be re-treated later. Under these conditions, conveyor belts, electric trams, aerial trams, and hose trucks, all gave satisfactory results, and the following figures, taken from "'West Australian Metallurgical Practice," will show how these methods compared as regards costs...

Jan 1, 1909