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By Darold Woodward, Stefan Haydn, Petr Pospisil

Most fatalities in tunnel fires are caused by the spread of toxic smoke. Controlling the spread of smoke is crucial to provide a survivable environment for emergency egress. A properly designed and tuned feedback control loop is required to achieve a target flow that is slow enough to allow pedestrians to escape under different boundary conditions. Feedback control loops are also helpful in optimizing energy consumption under moving traffic conditions. A reliable feedback flow control system requires sophisticated engineering knowhow and experience, careful selection of instruments and controlled variables, and thoughtful implementation from design through field testing and commissioning.

Dec 1, 2022

By B. K. Cantrell

The U.S. Bureau of Mines and others have conducted a number of occupational exposure surveys since the publication of the International Agency for Research on Cancer report of 1989, which labeled diesel exhaust as a probable human carcinogen. These surveys have assessed diesel exhaust exposure using measurement of diesel aerosol and/or specific polycyclic aromatic hydrocarbons as indicators of exposure. This paper reviews present diesel emission standards, available diesel exhaust aerosol measurement techniques, and the results of the occupational exposure surveys. In the surveys, diesel aerosol was emphasized because it is a major component of diesel exhaust, is suspected to contribute to the health hazard, and is readily measurable. Three primary aerosol measurement techniques were used: respirable combustible dust, size-selective sampling, and measurement of the elemental carbon fraction. Occupations surveyed included mine workers, railroad workers, forklift operators, fire fighters and truck drivers. The studies found mean diesel aerosol concentration levels in the range of 0.004 to 1.74 mg/m3? Highest aerosol exposures were in confined spaces such as mines where heavy diesel equipment is used. Polycyclic aromatic hydrocarbons typically are found at very low concentration levels and are not unique to diesel exhaust.

Jan 1, 1996

By Francis G. Stehli

Though sedimentary rocks comprise only about five percent of the volume of the continental crust, they cover about 80% of its surface, serve as important reservoirs for fluids, contain reserves of non-metallic minerals, and have in general been extensively drilled. However, most drilling has been shallow in comparison to the thickness of the crust and such deep drilling as has taken place is very strongly localized in sedimentary basins. This may be seen by reference to Figures 1 and 2 which show the location of wells that drilled deeper than 15,000' [=] 4.6 km. (Figure 1) and those that drilled below 20,000' [=] 6.15 km. (Figure 2). It is apparent that, even in regions of sedimentary cover, direct exploration below six kilometers has been very restricted. In the case of the metamorphic and igneous rocks which make up 95% of the volume of the crust, direct exploration has been much less extensive in terms of both area and depth. The present state of our knowledge of the crust below a' thin surface layer stands in marked contrast to our growing present need for raw materials and the needs of future generations. It also stands in contrast to our need for enhanced, scientific knowledge of the deeper crust, its configuration, its present state, its hydrothermal systems,-its evolution, and its materials. Lessons learned in exploring the third dimension of the sea floor, the vigorous prosecution of seismic profiling, the development of testable models for hydrothermal systems and mineral deposits, the need for better understanding of heat flow, state of stress, earthquake mechanisms, and a host of other phenomena all suggest that it is time to launch a national program for scientific exploration of the crust which uses drilling to test important hypotheses developed on the basis of indirect evidence.

Jan 1, 1985

By W. J. Atkinson

Since the inception of the Ashton (formerly Kalumburu) Joint Venture in 1972 the parties have expended 524 million in exploration for diamonds in the Kimberley region. This has resulted in the discovery of the currently subeconomic Ellendale deposits in 1976/77 and the economic Argyle - Smoke Creek Deposits in 1979/80. In addition to Argyle and Ellendale some 90 kimberlitic and lamproitic bodies have been discovered grouped broadly into three provinces, on the west, east and north margins of the Kimberley block. These bodies range in size from dyke-like features less than one metre in width to pipes with a surface area of 128ha. The bodies with larger surface area are volcanic crater deposits, infilled with air-fall and water deposited tuffs and epiclastic sediments.

Jan 1, 1984

New developments in the pipe conveyor and belt are advanced to address the growth in the capacity, length and complexity of pipe conveyor systems. Improved belt construction can offer better stability during horizontal curves and resistance to twist. Low rolling resistance rubber compound can significantly lower the power consumption and belt tension, producing capital and operation cost savings. Dynamic analysis, when used to analyze the conveyor?s starting and stopping behavior, can improve the design and reliability of long overland pipe conveyor systems. For these three aspects, technical backgrounds and field installations as examples are discussed in this paper.

Jan 1, 2012

By Lewis L. Oriard

The authors outline the development and application of blasting methods put into use 11 years ago at the Berkeley Open-Pit Mine, Butte, Montana. The blast design uses a very short delay (5 milliseconds) between detonation of explosives charges, a feature challenged several times in principle despite its success for Anaconda. Concern is expressed over the categorical rejection of very short delay blasting which can make the difference between success and failure of major mining operations. There is ample evidence to show that the method can be used successfully and not violate the concerns of the public.

Jan 1, 1980

By J. R. R. Bowling, A. McFadden, M. Francoeur

The abstract discusses the increasing use of extensive duct-fan systems in underground hard-rock mine development. It highlights the challenges of designing these systems, particularly the risk of partial vacuum and the need for careful booster fan positioning. The paper explores factors influencing the design of these systems, including component limitations, operational wear margins, and power constraints. It also defines the concept of partial vacuum and its impact on ventilation ducts. The authors propose an algorithmic approach for specifying the location and blade pitch of in-line booster fans to prevent system failure.

Mar 17, 2022

By Richard J. Lundin

Literature research is an inexpensive, yet effective tool for the direct discovery of ore deposits. Case studies abundantly demonstrate that properties with viable mineralization and *proven reserves have been overlooked, forgotten. or ignored and can be rediscovered by inexpensive literature search techniques Areal studies s as WaIlaby Enterprises Mining District Data Base Program appear to be more effective than traditional commodity studies. The success of such studies depends on the inclusion of Mineral Clairant Questionnaire Data, Mineral Ownership Data, Field Examination Data and the continual updating of all information. Such studies are valuable for proposed or existing Wilderness Area Evaluations.

Jan 1, 1977

By M. R. Shahan, C. E. Seaman, S. E. Mischler, T. W. Beck

"Float dust deposits in coal mine return airways pose a risk in the event of a methane ignition. Controlling airborne dust prior to deposition in the return would make current rock dusting practices more effective and reduce risks of coal dust-fueled explosions. The goal of this NIOSH study is to determine the potential of open-air water sprays to reduce concentrations of airborne float coal dust (<75 µm diameter) in longwall face airstreams. This study evaluated unconfined water sprays in a featureless tunnel ventilated at a typical longwall face velocity. Experiments were conducted for two nozzle orientations and two water pressures for hollow cone, full cone, flat fan, air atomizing, and hydraulic atomizing spray nozzles. Gravimetric samples show that airborne float dust removal efficiencies averaged 19.6 percent for all sprays under all conditions. The results indicate that the preferred spray nozzle is operated at high fluid pressures to produce smaller droplets and move more air. These findings can be used to select sprays and design spray arrays to control airborne float dust over the entire longwall ventilated opening. INTRODUCTION Coal mining processes produce airborne dust that naturally deposits on the floor, roof, and ribs of mine airways. These fine dust particles, termed float coal dust when smaller than 75 microns in diameter, are deposited in return entries of coal mines and can be re-entrained by pressure waves induced by methane-air explosions (Rice et al., 1911; Nagy, 1981; NIOSH, 2006). These particles are also those most likely to participate in coal dust-fueled explosions, which can potentiate and propagate explosions resulting in extensive damage. In order to meet compliance requirements of at least 80 percent incombustible content in the composition of material deposited in mine entries (CFR, 2016), coal mines apply an inerting agent, specifically, rock dust (Harris et al., 2009). Should methane be present in the mine atmosphere, the required fraction of incombustible content is further increased by 0.4 percent for each 0.1 percent methane. The removal of airborne float coal dust (AFCD) prior to deposition is an approach intended to make current rock dusting practices more effective by increasing the proportion of inert material to combustible material, resulting in a lower risk of coal dust-fueled explosions. Water sprays are both effective and widely accepted as a method for controlling underground coal mine dust. In fact, water sprays are considered to be the most economical and technically feasible means of reducing dust concentrations in underground coal mines (Courtney and Cheng, 1977; Barker and Humphreys, 1996). Sprays are used in several ways to control dust in mining processes: inhibiting dust formation, immobilizing dust to prevent it from becoming airborne, and capturing airborne dust (Cheng, 1973). Reductions in airborne dust concentrations have frequently been attributed to inertial impaction between water droplets and dust particles, forming larger agglomerates which then quickly precipitate out of the airstream (McPherson, 1993). Inertial impaction activity is generally accepted as the major capture mechanism for airborne particles larger than 0.5 µm in diameter. It is this mechanism that is evaluated in this study."

Jan 1, 2017

By L. B. Kirk, A. R. Kirk

At New World, Au-Cu-Ag mineralization occurs in stratiform car-bonate-hosted, massive sulfide-iron oxide, and skarn-replacement deposits. Regional pyritic-alteration, local massive sulfide mineralization and mine wastes generate acid drainage within the district. Water quality improves down gradient through dilution and mixing of acid and metal-rich mine water with bicarbonate-rich, low-metal surface and groundwater, and precipitation of metal-rich ferrihydroxide phases. Natural deposits of ferricrete indicate that pre-mining ARD has occurred, providing important clues to pre-mining water quality. The geoenvironmental model identifies the Cu-skarn mineralization as the primary target for ARD management. Closure success will be limited by the geoenvironmental nature of the natural mineralization.

Jan 1, 2004

By Jing G. Yen

When a solid-liquid mixture is conveyed through a pipe,&apos; four hydrodynamic conditions may develop depending upon the properties of the transporting medium, the properties of the transported material, the properties of the pipeline and the flow characteristics. They are classified as homogeneous flow, heterogeneous flow, intermediate flow and saltation. Heterogeneous flow, which is the subject of the present analysis, occurs when solid particles are coarse, of high density, and the mean velocity of the flow is relatively low, such that the combination allows the establishment of a pronounced concentration gradient in the cross-section of the pipe. In this type of system the suspended matter does not change the rheological properties of the conveying fluid, and solid and fluid phases behave somewhat separately. In recent years much work has been directed toward gaining more insight into the hydrodynamics of heterogeneous flow (1,2,3,4,5,) However, almost all knowledge obtained is empirical in nature and limited in scope. Much effort has been extended to collect experimental information on the energy losses associated with systems of slurry flow (6-13) The work of Durand and Condolios(14,15) represents one of the most extensive experimentations in this field. Through systematic test runs, the effects of the major flow-parameters were studied one at a time. From the results, they concluded empirically that:

Jan 1, 1969

By B. Cousins

Flotation reagents are critical to the optimum performance of flotation circuits. How a flotation reagent performs within the first few cells of a flotation train is a key indicator of how well it will perform throughout the entire circuit. A method to compare reagent performance was recently developed by Ashland Water Technologies. The procedure involves collecting a timed sample of concentrate from each cell and then measuring the volume of the settled solids. An estimate of the percentage of concentrate collected from each cell can then be mathematically determined, providing an understanding of the recovery changes in each cell. Data from trials at a coal flotation circuit are used to demonstrate the method&apos;s validity.

Feb 27, 2013

A charge of the Research Council of the Society for Mining, Metallurgy and Exploration, Inc. (SME) is to ?? identify longer term research ideas/needs, that in the perception of the SME Research Council, could represent significant technology breakthroughs ?? (SME, n.d.). In 2008, the Council decided that instead of unilaterally developing a list of top priorities, it would involve the entire membership of SME in identifying the top priorities. Additionally, it decided to keep the list short. This paper describes the process and results from that exercise.

Jan 1, 2010

By G. Deschênes

Following a successful investigation on the Central Zone sample, a cyanidation study was conducted on an ore sample from the AD-MW Zone of Clarence Stream Property, owned by Freewest Resources Canada, to develop a leaching strategy to extract gold. At a grade of 6.48 g/t, gold is present in the forms of aurostibite, free gold and electrum. The ore contains 4.3% berthierite/gudmundite, 1.3% pyrrhotite, 0.7% pyrite, 0.07% stibnite and 0.9% arsenopyrite. Similar to the Central Zone, the extraction of gold from the AD-MW Zone can be performed at atmospheric pressure, pH 10.5 and with a low concentration of cyanide. The grind size had no effect on gold extraction between a P80 of 28 to 71 µm. The oxygen and cyanide requirement significantly increased with a ?ner grind. Consequently, a very close control of cyanide addition is required to minimize passivation of gold. Lead nitrate, added in the pretreatment, increased the extraction of gold by 2.3%. Leaching at pH < 10 improved gold extraction but increased the cyanide consumption by 5%. Passivation of gold occurred when the pretreatment was longer than 2 hours. A longer pretreatment reduced the cyanide consumption by 5%. Mineralogical characterization of the leach residue with no gravity pretreatment prior to leaching indicated the presence of unleached gold grains and passivated gold grains. Removal of coarse gold by gravity increased the extraction by 2.8% (leach residue at 0.74 g/t Au). Increasing the DO to 16 ppm or the lead nitrate from 500 to 1,000 g/t increased the overall gold extraction to 90.4% (leach residue at 0.62 g/t), which is the maximum gold extraction obtained. The leaching parameters were 800 ppm NaCN, DO 16 ppm and pH 10.5 for a duration of 120 hours. The associated cyanide consumption was 4.0 kg/t. Gold leaching was not sensitive to cyanide concentration. Reducing the cyanide concentration to 250 ppm resulted in a gold extraction of 89.5% with a cyanide consumption of 2.6 kg/t.

Jan 1, 2009

By J. Tuck

This paper reports on an ongoing exploratory research program which aims to develop an understanding of the relationships between mining companies and their stakeholders and the importance of corporate citizenship policies to reputation and hence to corporate sustainability. The findings of the first stages of this research, the results of a focus group and an expert opinion survey into the drivers of reputation for mining companies are reported. This study was undertaken to provide an understanding of the drivers of reputation for a number of stakeholder groups and the perceptions held by mining companies of these drivers for their stakeholder groups. Results indicate that drivers vary between stakeholder groups - that in the case of drivers common to a number of stakeholder groups they may vary in their importance across the groups, and that there may exist a divergence between industry?s perception and stake-holders? priorities. These results further the understanding of the relationship between corporate citizenship and reputation in the mining industry, thus assisting companies to strategically manage their corporate citizenship investments and assisting them in their transition to sustainable development.

Jan 1, 2007

By Nasri Munfah, Steffen Matthei, Vojtech Gall

"Conventional tunneling as defined by ITA WG19 is also known as the New Austrian Tunneling Method (NATM) or Sequential Excavation Method (SEM) was transformed in the US to deal with challenging tunneling conditions as an alternative to the more traditional tunneling methods. It is being used more often in urban areas, under difficult ground and ground water conditions, and with limited cover. Often the tunnel is of a large and non-uniform cross section in soft soils or weak rocks. The intent of using this tunneling method is to minimize impact on traffic and utilities and reduce disruption of everyday life of people and businesses. To meet these challenges, the industry developed technical approaches and implementation techniques and established sophisticated contractual relationships and collaboration in the field among various parties for successful implementation. This paper examines the development of conventional tunneling (NATM/SEM) in the US to deal with these challenges using recent examples such as Russia Wharf in Boston, Northern Boulevard Crossing, in New York, and Chinatown Station in San Francisco. INTRODUCTION / HISTORY Conventional tunneling or NATM/SEM is a concept that is based on the understanding of the behavior of the ground as it reacts to the creation of an underground opening. In its classic form the SEM/NATM attempts to mobilize the self-supporting capability of the ground to an optimum thus achieving economy in ground support. Initially formulated for application in rock tunneling in the early 1960’s, NATM has found application in soft ground in urban tunneling in the late 60’s and has since then enjoyed a broad, international utilization in both rural and urban settings. In the US the NATM/SEM tunneling method has been used successfully to address challenging tunneling conditions in urban areas. A large number of tunnels have been built around the world using a construction approach which was loosely termed NATM. During the years of discussions and the application of NATM a variety of terms have been used for the same construction approach. These terms were primarily aimed at describing the construction approach rather than the region of its reported origin."

Jan 1, 2016

By Yoshihiro Kawarabata

INTRODUCTION With only about 30% of Japan&apos;s entire population served by sewer systems at the end of 1980, extensive sewerage construction programs have been implemented. As major sewer networks in large cities are near completion, construction of smaller sewer networks in less populated areas and branch sewers in urban areas is on the rise, where a demand for sewer tunnels of 600mm to 1500mm diameter is very heavy. The pipe jacking technique, usually employed to excavate such small diameter tunnels, therefore has become the subject of further technological development and sophistication to cope with the increasing volume of construction. At the 1979 RETC, the state of the art on the slurry shield tunneling method at that time was reported. This paper is a follow up to the last paper and discusses a newly developed boulder crushing equipment and automatic pipe jacking system for the slurry shield method and their application. Such technological advancement as high-degree mechanization and automation will significantly improve tunneling operations in response to the aging society to come. Through application of the technique on so called factory automation, this is a step towards field automation for the construction industry.

Jan 1, 1983

By H. H. Murray

Significant changes in ownership and production of industrial clays have occurred since 2000. Clays covered in this presentation are kaolins, ball clays, smectites, (bentonite), and palygorskite (attapulgite)-sepiolite. IMERYS discontinued production of paper coating kaolins at their Cornwall operations and have expanded their kaolin production in Brazil. J. M. Huber sold their kaolin operation in Georgia to KaMin whose headquarters are in Ft. Worth, Texas. BASF purchased Engelhard?s kaolin and attapulgite operations in Georgia. ActiveMinerals purchased Southeastern Kaolin in South Carolina, Wilkinson County Kaolin in Gordon, Georgia, and Zemex Attapulgite in Quincy, Florida. Chemical Lime purchased Spinks Ball Clay Company in Paris, Tennessee. Most of the ball clays used in Italy and Eastern Europe comes from expanded operations in the Ukraine. Bentonite operations have expanded production in Wyoming and Montana because of strong demand for drilling mud, foundries, cat litter, and iron ore pelletizing. The production and exports of palygorskite in China continues to increase. Nanoclays utilizing sodium montmorillonite, palygorskite, and halloysite are actively being developed.

Jan 1, 2009

By T. Grammatikopoulos, C. Gibson, M. Aghamirian

"Lithium is a silver-white alkali metal that has recently become a target commodity for many junior mining companies. Lithium has a wide range of applications including ceramics and glass, lubricating greases, air treatment, continuous cast mold flux powders, polymer production, and primary aluminium production, but the current popularity of lithium can be attributed to an anticipated increase in demand for lithium ion batteries. The most common lithium-bearing minerals occur globally in pegmatites and granites. Spodumene [LiAl(Si2O6)] is the most desirable economic lithium-bearing mineral due to its high lithium content (theoretical Li2O content of about 8 wt%). However, lithium can also be hosted in petalite, micas, tourmaline, and phosphate minerals. In Canada there are a number of spodumene deposits in Ontario and Quebec at development stage that have the potential to help narrow the forecast lithium supply gap stemming from the widespread acceptance and use of electric vehicles. This paper discusses the beneficiation of hard rock lithium deposits, including an in depth review of the use of flotation to upgrade spodumene. A review of the use of dense media separation (DMS), magnetic separation, and roasting as means to process spodumene bearing ores is also discussed. INTRODUCTION Lithium is a soft, silver-white alkali metal with atomic number 3. As of 2015, the end use of lithium was estimated to be as follows: lithium-ion batteries (35%), ceramics and glass (32%), lubricating greases (9%), air treatment (5%), continuous casting mould flux powders (5%), polymer production (4%), primary aluminium production (1%) and other uses (9%) (Jaskula, 2014). Lithium is found in brine lake deposits containing lithium chloride and in hard rock pegmatite deposits. It can be sold in a range of product types; as mineral concentrate, brine, compound (lithium carbonate or lithium hydroxide) and metal depending on its intended end use (Goonan, 2012; Jaskula 2014). In the 1990s the United States and Chile were the largest producers of lithium globally, primarily from brine operations (Ober, 1994). Most of the lithium compounds produced over this period were consumed in the glass, ceramics and aluminium industries. In the 1980s and 1990s there were two major lithium operations in the United States: brine operations at Silver Peak, Nevada, and a spodumene mine and lithium carbonate/lithium hydroxide plant in Kings Mountain, North Carolina. The Kings Mountain operations ceased production in 1991 and were eventually dismantled in 1994. Brine operations were also active in Argentina and Chile, while the largest lithium ore deposit in the world was operated at Greenbushes, Western Australia. During this period it was predicted that major shifts in demand for lithium would come from the success and widespread use of electric vehicles (Ober, 1994)."

Jan 1, 2017

By Lei Fu

In the wake of the collapse of the ceiling panels in the I-90 section of the Central Artery/Tunnel (CA/T) Project in 2006, the long term performance of tunnels became the focus of the tunneling industry. At the time of the accident, the tunnel had been open to traffic for about 10 years. This paper will discuss design methods and considerations to improve the long term performance and durability of a tunnel. The major problems found during the inspection of several tunnels will also be presented and the causes for these problems will be discussed.

Jan 1, 2008