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By Juan Camus

To understand why some companies excel in creating value, Jim Collins (2001) and a group of postgraduate business students engaged in a comprehensive, five-year research project. They examined 1,435 U.S. companies for more than 40 years, seeking those that made significant improvements in their financial performance over time. The distinctive pattern sought was: ?Fifteen-year cumulative stock returns at or below the general stock market, punctuated by a transition point, then cumulative returns at least three times the market over the next 15 years. ?The search identified 11 outperforming companies, all in different industries, that were called the ?good to great? companies. To contrast these companies with similar peers within the same industry, the search also selected a group of comparison companies that failed to make the leap from good to great. Collins then set out to examine the transition point. What distinguishing features did the good-to-great companies have that their industry counterparts did not? At the heart of the findings about these outstanding companies is what Collins refers to as the ?hedgehog concept? ? how to find the one big thing that the company must focus on. According to Collins, those who built the good-to-great companies were, to one degree or another, hedgehogs. Those who led the comparison companies tended to be foxes, never gaining the clarifying advantage of a hedgehog concept, being instead scattered, diffused and inconsistent. This insight is complemented by Peter Drucker (2004), an influential management guru, who asserts that the first question an effective executive should ask is: ?what needs to be done?? Asking this question and taking it seriously, he asserts, is crucial for managerial success; and that the answer almost always has more than one urgent task, but the effective leader only concentrates on one task. In this last respect, Drucker emphasizes: ?If they [executives] are among the sizeable minority who work best with a change of pace in the working day, they pick two tasks. I have never encountered an executive who is effective while tackling more than two tasks at a time.?

Jan 1, 2011

By Marvin P. Barnes, John G. Simos

The Park City District, Utah, is situated in the Wasatch Range at the intersection of the westward extension of the axis of the Uinta Range. Ore has been mined almost continuously from the first discovery in 1869 to the present day, with a total production of over 14 million tons. Sediments of Carboniferous to Triassic age have been folded into the northerly plunging Park City anticline and subsequently modified by thrust faulting, diorite and diorite porphyry intrusions, and strong east-west normal faulting during the Laramide orogeny. Younger andesitic volcanics partially cover the eastern edge of the district. The ore bodies occur as both lode and bedded replacement deposits over widely scattered localities. Near surface, high-grade silver "bonanza" ores were mined in early days from the Ontario and Daly Lodes, which occur along the east-west zone of faulting near the center of the district. Other lode or fissure deposits were found along the Mayflower and Hawkeye faults to the east and southeast. Large bedded replacement silver-lead-zinc ore bodies associated with east-west zones of fissuring, have been mined from favorable horizons in the Park City Formation in the Daly West and Judge mines. A series of long, narrow, high-grade, replacement ore bodies occur in the Silver King mine at a single horizon in the Park City Formation. Ore is currently being mined from strong bedded replacements in the Humbug Formation near the apex of the Park City anticline. Factors controlling ore deposition are: magmatic source, structural feeder systems, and favorable host rocks. Ore deposition along favorable beds is primarily a function of physical conditioning and secondarily of chemical composition.

Jan 1, 1968

By Jason Morrison

The Norwegian Lake Tap Method was successfully used to tap into the side of Lake Dorothy 36.5 m (120') below the lake surface. The lake tap allows water to flowinto an access tunnel from the lake lowering the water elevation below its natural out-fall. When the lake reaches a predetermined elevation below the outfall, a 1.5 m (60?) valve in the tunnel will be shut and discharge from Lake Dorothy will stop temporarily allowing construction of a dam located 2.9 km (1.8 miles) downstream at Bart Lake. The lake tap and tunnel were one phase of the $64 million Lake Dorothy Hydroelectric Project, owned and operated by Alaska Electric Light & Power Company (AEL&P), a private utility located in Juneau, AK. The Lake Dorothy portal site and tunnel are located approximately 25.7 km (16 miles) southeast of Juneau, AK, in the remote Tongass National Forest at an elevation of 701 m (2,300') above sea level in the mountains above the Taku Inlet. Thirty degree snow covered mountainsides and limited access by helicopter were just two of the many factors which challenged this unique project. The lake tap and tunnel development consisted of 250 m (820') of horizontal tun-nel, averaging 3.6 m x 3.6 m (12' × 12'), excavated using conventional drill and blast methods in highly competent Granodiorite and Tonalite rock, placement of one 3.9 m (13') long concrete plug, or bulkhead, located at the tunnel midpoint, and one 3 m (10') diameter lake tap into the side of Lake Dorothy. This paper will provide an analysis of the logistical and engineering challenges involved in the development of one of only a handful of lake taps in North America. AEL&P and contractor J. S. Redpath Corporation worked together to complete this critical project phase safely and on schedule, in a location accessible only by helicopter and plagued by constantly changing, harsh weather conditions. A strict schedule had to be maintained to ensure the timely operation of the downstream dam and power plant.

By Steven J. Page, John A. Organiscak

Laboratory crushing experiments were conducted on a range of low- to high-volatile bituminous coals to investigate the various factors influencing airborne respirable dust (ARD) generation. This research was conducted to identify the principles of ARD liberation from the coal product. Five U.S. bituminous coals were uniformly prepared and processed through a double roll crusher located in a low-velocity wind tunnel. Experimental factors studied included inherent coal seam constituents, coal grind ability, specific energy of crushing, product size characteristics, dust cloud electrostatic field, and specific ARD generated. The results of this investigation indicate that a combination of several factors are associated with ARD generation. One factor is the effect of coal rank, described by the inherent moist fuel ratio, on the product size characteristics, defined by Schuhmann size function parameters. Another key factor is the effect of air dry loss(ADL) moisture in the coal seam on the breakage-induced electrostatic field of airborne dust. The effect of these factors is that different percentages of <10-m coal particles are dispersed as ARD. A discussion of electrostatic field principles, coal ADL, and its effect on ARD generation is presented.

Jan 10, 1998

By Edward A. McClatchie

A novel nondispersive electro-optical gas analyzer has been designed, fabricated and tested. The instrument is based on a pressure modulated absorption technique. Key features of this new gas analyzer technique include long-term zero and calibration stability. The technique was investigated for the gases carbon dioxide (CO2), carbon monoxide (CO), methane (CH4) and nitrogen dioxide (NO2). The delivered analyzer was capable of measuring the three species CO, CO2 and NO2. It is a compact (300 cu in) package, is battery powered and weighs 15 lbs. Some thirty readings of each gas may be made on a single battery charge.

Jan 1, 1980

By J R. Leeming

Mines require ventilation to ensure an adequate atmosphere for the sustenance of life, and to dilute, render harmless and remove contaminants.This paper describes the developments in the United Kingdom (UK) from natural ventilation, through the introduction of fire and simple fans, to modern fully independent and remotely monitored and controlled installations.CITATION:Leeming, J R, 2017. The history of mine ventilation in the United Kingdom, in Proceedings Australian Mine Vent Conference 2017, pp 271–276 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 28, 2017

By Michael Kelly

Inertial navigation technology has, for the first time, allowed the position of a longwall shearer to be mapped in three dimensions. Following the success of the technology in highwall mining and successful trials on a longwall face, the Australian Coal Association Research Program (ACARP) commissioned a three year "Landmark" project that aimed to advance longwall automation to the level of "on-face observation" by the end of 2004. This project has been completed with the following successful technical outcomes: Automatic face alignment was achieved, using an inertial navigation-based sensor on the shearer, to accurately measure face geometry and feedback signals used to move OEM (Original Equipment Manufacturer) roof supports. Operational on-line measurement of creep with creep information incorporated into face alignment corrections. Inertial Navigation System (INS)-based enhanced horizon control was bench-tested. Operational broadband communications system to shearer using wireless Ethernet on a commercial-product basis. Acquisition of located coal-face features for use in thermal infrared-based horizon control. Automated Longwall Information System (LIS) developed which integrates information from multiple systems and sensors and provides high quality visualisation and control interfaces. Automatic roadway and face convergence monitoring tools successfully tested. Condition monitoring tools developed and demonstrated for improved face reliability. This paper summarises the outcomes of the project and describes the work being undertaken for the 2 year Landmark Extension project approved in April 2005. Consistent with the conference theme, the paper focuses on the ground control aspects of the project.

Jan 1, 2005

By Scott G. Honan, Wayne F. Luinstra

"Since 1992, the concentration of gold using gravity methods has progressed to become an important part of production at Hemlo Gold's Golden Giant Mine. Currently, the gravity circuit accounts for approximately 25% of the Golden Giant Mine's Gold production. This circuit consists of a 30 inch Center-Drain Knelson Concentrator and a Shaking Table. The evolution of gravity concentration will be discussed with an emphasis on the economic justification for a gravity circuit as well as the practical aspects and metallurgical impact of operating such a circuit. It will be demonstrated that the operation of a gravity circuit has definite benefits to the operation of the Golden Giant Mill and will continue to play an important role in future gold production.1.0 IntroductionHemlo Gold Mines Inc. Golden Giant Mine is a 3000 TPD underground gold mine and milling facility located 40 km east of Marathon, Ontario. Mining is accomplished by means of sublevel longhole open stoping. The ore is processed using conventional crushing, 3-stage ball milling, conventional cyanidation and CIP processes. The mill and concentrator are described in more detail in other publications1,2.Since July of 1992, the Golden Giant Mine has been using a gravity circuit for gold recovery in the mill's grinding circuit. Despite the fact that gold recovery averages over 96% using conventional cyanidation and carbon-in-pulp processes, the gravity circuit has become an integral part of milling operations. This paper will discuss the economic justification for a gravity circuit as well as the practical and metallurgical aspects of its operation."

Jan 1, 1996

By A. C. Johnson

The T. L. shaft of the Eureka Corp., Ltd., near Adams Hill, Eureka, Nev., was sunk in 1954 and 1955 to permit exploration and development of the lead-zinc-silver ore that had been indicated by drilling. This paper describes the sinking of the 4-compartment, vertical shaft to a depth of 1,127 feet and includes pertinent details of equipment, methods, and costs. A shaft crew of 10 men, supplemented by 13 hoistmen, topmen, carpenter, and shop crewmen, sank and timbered the 1,127 feet of shaft in 630 workdays. Total labor per foot of shaft was 107.95 man-hours. Supplies per foot of shaft included 20 pounds of explosives, 1.61 pounds of drill steel, and 200 board-feet of timber. Power consumption, including that required for pumping, averaged 3,726 kw.-hr. per foot.

Jan 1, 1958

By F. E. Spencer

Calculated equilibrium data are presented for three phases in the flue gas stream from a hypothetical open cycle MHD generator. A typical coal is "burned" with 1.0 gram-mole K2O seed per kilogram coal and with 101 percent of stoichiometric air. Tables of composition and the overt thermodynamic properties, enthalpy and entropy, are given for the temperatures 2200 (-100) 1100 kelvins, pressures 1.0 and 1.5 atmospheres, and slag rejection figures of 90 and 75 percent.

Jan 1, 1973

By Ayman Tawadrous

Cave mining offers a flexible technique to exploit large, low grade, deep ore bodies with low operating costs. It is typically done in either a top down approach; i.e. sublevel caving, or in a bottom up approach; i.e. block or panel caving, to extract ore bodies that may have been previously considered unfeasible to mine. Sublevel Cave (SLC) mining, in particular, is a cave mining method based upon the utilization of gravity of blasted ore while the overlying host rock fractures and caves under induced stresses and gravity. Thereby the caved waste originating from the overlying rock mass fills the temporary void created by ore extraction to achieve a controlled collapse of the roof.

Jan 1, 2015

By E. Barnard

Tarkwa Gold Mine is located in south western Ghana, and is majority owned and operated by Gold Fields Ghana Limited. The Tarkwa CIL plant utilises a single low aspect 27&apos; x 42&apos; 14MW dual pinion drive SAG mill designed to mill 4.2mtpa (525tph). The plant was designed and constructed in a manner that would facilitate its expansion to 8.4mtpa (1,050tph). Since the plant was commissioned in September 2004, the SAG mill has consistently exceeded its nameplate throughput by up to 25%. Through the installation of a 26? x 36? 14MW dual pinion drive Ball mill along with additional upstream and downstream equipment, the plant will now be expanded to 12mtpa (1,500tph). This paper endeavours to outline the process and engineering design challenges along with the future construction challenges of the expansion in the midst of a fully operational plant.

Jan 1, 2008

By William R. Yernberg

The Society of Economic Geologists (SEG) held its biennial conference May 14 through 16, 2006, in Keystone, CO. SEG is an international organization with about 3,500 individual members with interests in economic geology. The 2006 SEG conference theme was “Wealth creation in the minerals industry — integrating science, business and education.” The conference exceeded expectations with 705 participants, including 102 students, from 44 countries. The conference featured 30 oral presentations, 24 professional posters and more than 70 student posters. The conference also included a trade show with 50 vendors, numerous field trips, workshops and social activities.

Jan 1, 2006

By Edmond J. O’Donovan

South Bulga is a new longwall operation located in the Hunter Valley coal-mining region in Southeastern Australia. The mine’s objective is to achieve productivity levels significantly higher than the current industry average. From the day longwall production began, South Bulga’s output was below both budget and industry expectations, primarily because of the poor performance of the conveyor system. In the past, conveyor systems have been seen as an adjunct to the mine plan, not as an integral part. At past production levels, this approach may have been acceptable. In today’s mining operations, the conveyor system must be treated as integral and vital to the mining operation. The conveyor system is analogous to the vascular or circulatory system of the human body. Of itself, the system does not do anything, but if it is not functioning satisfactorily, the mine cannot operate.

Jan 1, 1996

By Lixun Kang

Bedded structure is the characteristics of coal measures strata. Bedding planes, coal streaks and soft rock bands existing in roof strata destroyed its continuity in the direction perpendicular to the coal seams. The statistics from a large number of long wall faces in which serious roof fall accidents occurred in Datong coal mining area suggest that beddings planes, coal streaks, soft rock bands, especially the first layer thickness of immediate roof have a great influence on its stability. As the first layer thickness increases, the probability of serious roof fall accidents decreases. Based on the investigations finite element method is used to analyze stress and displacement in the first layer of immediate roof. The results indicate that the thicker the first layer is, the less the roof convergence in the unsupported area is. Stress and strain features in stratified immediate roof are quite different f7om those in non- bedded immediate roof. In stratified immediate roof, every stratum has each own tensile zone in the upper portion and compressive zone in the lower portion, while tensile zone in the first layer is less, the tensile stress is the greatest.

Jan 1, 2005

By G. E. Cole

"Amongst the mineral products of Canada gold holds the second place in value of yearly output. . . . . .The production of gold has increased steadily during the past six years and has somewhat more than doubled in that time. For the past four years Canada has been third among the gold producing countries of the world, surpassed only by the Union of South Africa, and the United States of America," and now yields somewhat more than 9 per cent of the annual output of the world."-"The Gold Situation in Canada". Bulletin of Development Branch, Canadian Pacific Railway. The history of gold mining in Canada is comparatively modern and does not take one further back than the late &apos;fifties of the 19th century. If the efforts of the early explorers in Canada were expended in "seeking with equal ardour, proselytes and gold", history fails of any record of their success in the search for the precious metal. As early as 1849 not a few Canadians travelled from the east by land and water to the Californian goldfields. In the then settled part of Canadathe east-people were alive to the value of any mineral discovery; but the west, owing to its remoteness and to there being no ready means of communication, was virtually isolated from the east.

Jan 1, 1927

By A. L. Anderson, J. T. Rybock

KEECO has developed the Silica Micro Encapsulation (SME) technology for the treatment of acidic, metal-laden waters. Utilizing a silica-based chemical formulation that entails chemisorption and micro-encapsulation of heavy metals in a permanent silica matrix, encapsulated particles settle quickly and are effectively isolated from the surrounding environment, producing a stable sludge that is characteristically non-hazardous. In a number of independently-verified pilot and full-scale applications (including the Bunker Hill Mine, Leviathan Mine, Wheal Jane Mine, and Meldon Quarry), SME has been proven highly effective. The technology has been featured in a number of mining publications and selected for innovative technology awards.

Jan 1, 2000

Truck fires in a tunnel can create heat release rates (HRR) significantly higher than 100 MW. Because of a fast spread of smoke and heat the self-rescuing period is shortened significantly. Furthermore, it was experienced that firefighters are not able to approach the fire because of enormous heat and radiation. As consequence, the fire may spread to adjacent vehicles, which is reported for distances of more than 50 m. Tunnels can be damaged severely by fires and the repair works causes long closing time of tunnels. In addition to direct costs for the refurbishment of the tunnel, further economic losses will occur due to the closure time. Conventional deluge systems in Japanese and Australian road tunnels have been known since the 1960s. During the last years the research work was concentrated in the development of more effective and cost-effective solutions based on water mist technology. Orientating fire tests as well as specifications of minimum requirements were carried out within the European research project UPTUN. This basic work was extended by the safety of life in tunnels (SOLIT) research project, funded by the German government. The scope of SOLIT was not only to study the effects of water mist fire suppression systems in tunnels, but also the interactions with other safety systems, such as fire detection, passive fire protection or ventilation. Furthermore, the integration of active fire suppression systems into a holistic tunnel safety system was part of the work program. Within this research project a large-scale fire test program with more than 50 fire tests, including 25 truck fires with a potential HRR of almost 200 MW, was carried out in the test tunnel of San Pedro des Anes (Spain). Furthermore, a two-week testing and training period with the Madrid Fire Brigade was carried out after the SOLIT program. Two fundamental results were achieved during the fire tests:Primarily, water mist systems are able to control the HRR of fires in tunnels, so the atmosphere will be improved significantly. Hazardous effects of toxic smoke on people will be reduced and due to the reduction of temperatures and radiation, a firefighterÆs approach is improved significantly. Furthermore, the fire spread will be hampered and the thermal load on the building structure also be reduced. Secondarily, due to positive interactions with the ventilation system, the effectiveness of a tunnel ventilation system, longitudinal as well as semi-transversal, is increased significantly. Based on the results of the SOLIT research project, a water mist system was applied into several parts of the M30 tunnels in Madrid. As a basic principle the technical equipment and the methodology of implementation comply with the UPTUN 251 guidance, recommending minimum standards for water-based fire suppression systems in tunnels.

Jan 1, 2008

By K L. Brown

Sampling and analyses of deep waters from Wairakei and Rotokawa geothermal systems indicate a wide range of precious metal concentrations (&lt;0.1 to 23 ppb Au; 6 to 2400 ppb Ag), suggesting that eastern ôandesiticö TVZ geothermal systems (eg Rotokawa) have higher aqueous gold and silver than western ôbasalticö geothermal systems (eg Wairakei); this interpretation is consistent with known occurrences of high grade precipitates in wells from eastern systems. The fact that the deep waters are undersaturated in gold further suggests that the aqueous gold concentrations of deep waters are limited by metal availability. The flux of gold for the two systems ranges from ~1 to 50 kg Au/yr, and the flux of silver ranges from 65 to 6900 kg Ag/yr. At Rotokawa, it only takes ~600 years to flux one million oz of Au and &gt;100 million oz of Ag. The supply of hydrothermal gold and silver is obviously important during genesis of an epithermal deposit, but ore formation also depends on the existence of a suitable ôtrapö that efficiently extracts metal from solution in a small volume of rock. Such traps seem to have been poorly developed until geothermal drilling in the TVZ.

Jan 1, 2006

By G. P. Tomaino

Talc is a layered, hydrous magnesium silicate mineral. It has a soft, soapy feel and typically a smooth texture. Talc is also known for its insulation, heat resistance, chemical stability, oil absorption and strong covering quality. Talc, Mg3Si4O10 (OH)2, has a theoretical chemical composition of MgO at 31.7 percent, SiO2 at 63.5 percent, and H2O at 4.8 percent. However, talc’s chemical and mineralogical composition can vary depending on its geological history/parent rock association. These mineral associations and variable levels are usually chlorite and carbonates (magnesite, calcite and dolomite). Two key elemental substitutions that can occur in the talc crystal structure are iron for magnesium and fluorine for hydroxyl. These compositional differences may limit or enhance the talc’s usage in specific market niches. The United States remains self-sufficient in most grades of talc.

Jan 1, 2005