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By William Connell

NFPA 502, Standard for Road Tunnels, Bridges and Other Limited Access Highways establishes minimum fire protection and fire life safety requirements for road tunnels, bridges and other roadways where access by emergency responders is physically limited. The 2008 edition of NFPA 502 represents the Technical Committee?s consensus of current best practice for fire protection and life safety requirements for road tunnels, bridges and similarly limited access highways. Research of national and international test programs, design guidelines and regulating standards was per-formed and considered in an effort to establish a singular, comprehensive document representing a recognized base threshold of fire safety in these type facilities. This paper provides an overview of the more significant revisions including the application of fixed fire suppression systems, guidance on tenable environment, protection of structure and dangerous goods transport.

Jan 1, 2008

By E. Piesch, M. Urban, G. M. Hassib

INTRODUCTION In radon dosimetry diffusion chambers with passive [a]-detectors are now in current use to investigate the long-term accumulated indoor exposure of radon and daughters. For the diffusion chamber developed at Karlsruhe the electrochemical etching technique (ECE) was applied to reveal [a]-particles in polycarbonate plastic detectors. Compared to conventional etching, the main advantages of the ECE are the large track diameter, simple track counting in a single field of about 1 cm2, stability of the latent tracks to humidity and temperature and ability for a long-term accumulation up to 1 year. The electrochemical etching system was designed to etch in one run about 101 foils by using a 200 W high voltage generator. The commercial available radon dosimeter system is applied for a country wide program of measuring radon in dwellings. Because of an increasing interest of radon monitoring in mines, environmental monitoring and personnel dosimetry the properties of several track etch detectors have been studied. In the comparative study, Makrofol E, LR 115 and CR 39 were used in the diffusion chamber to investigate the etching techniques, the relative efficiency, the measurable [a]-energy range, and the counting statistic for the measurement of radon concentration. THE KARLSRUHE DIFFUSION CHAMBER The design of the Karlsruhe diffusion chamber is presented in Fig. 1. The upper part of the chamber is closed by a fibreglass filter to separate radon from aerosols, heavy dust particles and radon decay products. Inside the diffusion chamber [a]-particles from radon and daughters are detected by two passive radon detectors, one on the bottom of the chamber and the other in front of the filter. With the fibreglass filter applied the diffusion time is about 1 minute for radon. Therefore, also short-term variations in the radon concentration are recorded by the track detector. Mainly because of the short halflife of thoron (56 s) only about 7 % of the thoron concentration is expected in the diffusion chamber. Radon monitoring provides the estimation of the long-term accumulated mean value of the radon concentration with a lowest detectable concentration of 0.1 pCi/1 after 3 months accumulation by using polycarbonate track etch detectors, an electrochemical etching technique and track counting in a single field of 1 cm2. The diffusion chamber was optimized for the polycarbonate track detector with respect to chamber geometry and detector position [1]. Table 1 presents data for 3 different diffusion chamber designs. The radon sensitivity of the diffusion chamber depends on the [a]-energy discrimination and the angular response of the [a]-track detector. The difference between foil No 2 and foil No 1 can be explained by an additional plate-out effect of radon daughters on foil No 3. The high sensitivity of foil No 3 compared to that of foil No 2 is caused by an increase of the effective volume and the effective area for [a]-particle from radon and from plated-out decay products, respectively. Additional experiments have been performed in order to investigate the electrostatic properties of the plastic material and the properties of the diffusion filter [1]. The properties of bare a-detectors were compared with those inside the diffusion chamber. In contrast to laboratory results, dust particles deposited on the detector surface or in the environment of the detector obviously affect the reproducibility of the bare detector significantly. After 4 months exposure in dwellings the scatter of 10 dosimeters exposed in the same room exceeds a factor of 3 compared to 15 % for the diffusion chamber. COMPARATIVE STUDY OF TRACK ETCH DETECTORS Detector types and evaluation technique In the comparative study the properties of the following plastic track etch detectors have been applied: - LR 115 from Kodak Pathé, France, is a red dyed cellulose nitrate layer of 13 µm thickness on a 100 µm thick polyester support. The holes appears as bright spots in a dark red background. In an optical microscope counting of through etched [a]-tracks which must penetrate the detector layer - CR 39 from Pershore, England, is an ally1 diglycol carbonate plastic of about 300 m thickness. The normal etched [a]-tracks are counted by an optical microscope and the ECE [a]-tracks by a microfiche reader.

Jan 1, 1981

By Howard J. Haselhuhn

"The effectiveness of reagent adsorption onto hematite ore particle surfaces is critical during beneficiation to promote effective selective flocculation and dispersion and increase iron oxide recovery. The relationship between aqueous calcium in the process water and the effectiveness of common iron ore dispersants has never before been studied. The nature of common dispersants was studied in the presence and absence of calcium in the process water. The settling behavior of hematite-rich iron ore at pH 11 was assessed in the presence of calcium and inorganic dispersants: sodium silicate, sodium tripolyphosphate (STPP), sodium hexametaphosphate (SHMP) and organic dispersant ethylenediamenetetraacetic acid (EDTA). It was found that inorganic dispersants are ineffective at a pH of 11 without activating the surface sites of the ore particles with calcium. Organic dispersants, however, were found to be effective with and without surface site activation.IntroductionThe United States produced 54 million metric tons of concentrated iron ore in 2011 (Jorgenson, 2013). Over 8 Mt were produced using a process known as selective flocculation and dispersion (CCI, 2011). The grade of this ore is slowly depleting, making it imperative that processing efficiency improves. To increase processing efficiency, a complete understanding of the effects of chemical reagents in the process must be acquired. This process relies heavily on dispersants to disperse iron oxides from gangue minerals in settling processes. The mechanism that these dispersants use to disperse the ore and its relationship to calcium in the process water has never been studied. The following extended abstract summarizes the relationship between aqueous calcium in process water and the effectiveness of common iron ore dispersants at dispersing hydrated hematite ore. These tests were carried out at a pH of 11, as this is a typical pH used to ensure dispersion in selective flocculation and dispersion processes."

Jan 1, 2015

By S. J. Schatzel

Coal mine longwall face ventilation is an important component of the overall mine ventilation system. Increases in the production rate due to higher capacity mining equipment tend to increase methane emission rates from the coal face, which must be diluted by the face ventilation with a minimal opportunity for assistance from additional control equipment (i.e., surface boreholes). Increases in panel length, in some mines approaching 6,100 m (20,000 ft), and panel width provide additional challenges to face ventilation designs. Face ventilation can also be affected by communication with the methane-laden gob gas reservoir. Except in a two-entry system, belt air cannot be used to ventilate the face in the US, except in limited cases. This relatively recent requirement has further challenged the mining industry in maintaining adequate longwall face ventilation. To assess the effectiveness of current face ventilation practices, a face monitoring study was combined with a tracer gas test on a longwall face. The study was conducted at a US mine operating in a thick, bituminous coal seam with some self-heating tendencies. Multiple gob gas ventholes were located near the face and produced a small portion of ventilation air in their production flow. Initial results show that emission rates on the longwall face showed a very limited increase in methane concentrations from headgate to tailgate despite the occurrence of methane delays during monitoring. Increases in methane concentrations in the tailgate entry in the vicinity of the longwall face T-junction appeared to be produced primarily by gas flow from the gob, not from increased emissions from the face. Barometric pressure variations were substantial over the course of the study and varied on a diurnal basis, as is typical of many mining operations. Suggestions are forwarded for reducing longwall face methane concentrations.

Jan 1, 2012

By A. Martikainen

Field tests concerning a fog mesh method for fog removal are discussed. The first tests were performed at the Pyhäsalmi Mine, Finland. As this study gave promising results, further studies were completed at the Orivesi Mine. The results of these most recent field tests are presented and the two studies are compared. The Orivesi test set consisted of four materials. These included air filter fabric, fibrous filter fabric, a plastic greenhouse mesh, and an aluminium mosquito net. The variation of the Orivesi results was more noticeable than what was found previously. The best fog removal effect of all tests was achieved with the aluminium mosquito net, while the plastic green-house mesh performed worst. The humidity reduction by aluminium net was more profound than any of its precedents. More mesh materials will be tested in the near future.

Jan 1, 2007

By Christian Neumann, Josef Arnold, Albin Reinhart

The Channel Tunnel Rail Link (CTRL) is the most significant railway infrastructure development project in the United Kingdom since the construction of the Channel Tunnel between France and England. The key element of this project is the 2-mile-long(3.2-km) North Downs Tunnel, which will be the largest and deepest twin-track railway tunnel ever constructed in the United Kingdom. This paper describes the contractual agreement, the design and construction (excavation and lining) of a twin-track rail tunnel with a 166-m 2 face excavated through chalk using the New Austrian Tunnelling Method (NATM). The importance of collaborating with a tunnel contractor/designer who not only is expert in the New Austrian Tunnelling Method, but who was also responsible for the design and installation of the primary lining, will be highlighted in this paper. This paper will also deal with the benefits of partnering in tunnel design and construction, as well as the resultant added values of mechanizing conventional tunnelling methods (Value Engineering).

Jan 1, 2001

By K. Burke, K. L. Myers, R. Espell

Barrick Goldstrike’s (Goldstrike) AA Heap Leach Pad is an HDPE lined facility used for gold recovery from low grade ores using conventional cyanide heap leach technology, operated from 1987 through 1999. Goldstrike prepared a unique reclamation plan for the AA Leach Pad Facility to provide for a cost-effective, environmentally sound facility closure and to fulfill the State of Nevada’s closure requirements. Traditional Nevada leach pad closure has involved rinsing to reduce cyanide concentration to an acceptable level, followed by reclamation. However, certain metals and compounds are not typically reduced by rinsing and some constituents may increase in concentration with rinsing. A closure scenario to effect limited infiltration through installation of a capillary cover for the leach pad was developed. The capillary cover was constructed by placing a fine-grained layer above the coarse-grained spent leach material to create a capillary break. In an arid climate such as Nevada, the fine-grained layer will rarely reach full saturation and the cover will be able to store water during precipitation and allow removal of water through evaporation and transpiration (ET) during the growing season. A 1.22 m (4 ft) cover thickness was selected as the optimum design cover thickness. The drainage network on the surface of the re-contoured AA Heap Leach Pad was specifically designed to enhance the revegetation, reclamation, and sediment yield control aspects of the AA Heap Leach Pad closure, while resulting in a natural looking surface, compatible with the surrounding topography. Adjacent natural topographic features were used to establish target design parameters for re-contouring and erosion control design.

Jan 1, 2001

By F. F. von Glehn

There is no doubt that simulated ventilation networks must be adequately verified before they can be extrapolated and used for predictive purposes. There are two general approaches as to how the verification can be established and these are summarised as follows; The first approach is to measure all individual branches with trailing hoses or barometers to get individual pressure drop and flow per branch and then calculate individual resistance factors for input into the software. The simulator is run, checking that the output makes general sense (check some sensitivities if possible). The network is now considered as verified. The pressure drop to be measured is relatively small and thus it is inherent that the measured set of individual K factors will be imprecise no matter how much care is taken in the measurements and the resultant simulations will inherit the same problem. In the second approach, the network is assembled using estimated (Atkinson) K factors (based on physical features of airway, past experience and catalogued typical K factors). Only the main primary flow rates are measured and hence the relative distribution of the primary ventilation in the main airways is determined (probably about 10 off primary air flow measurements). Main critical pressure differentials at main and booster fans and across critical doors are measured (probably about 6 off primary pressure differential measurements need to be made). The simulator is run and the computer model is used to iterate and select an updated suite of K factors so that the flow balances and pressure differentials are correctly simulated (typically only 2 or 3 iterations are all that is needed). The network is now considered as verified. The pressure differences to be measured will be substantial in absolute terms and can be measured with high precision. Also, because only primary flows are measured, these will generally be measured at higher air speed points and hence improved relative accuracy. This leads to more accurate simulation results. This paper examines the advantages and disadvantages of the two approaches. 1 Background

Jan 1, 2009

By L. "Andy" Anderson, Stephen N. Short, James E. Friant

Since the introduction of "boxhole" drilling in South Africa in 1973, the concept of a blind raise, drilled upward from below, has become an accepted mining practice. A combination machine, capable of constructing raises to a mining level below, or blind raising upward from a single setup position adds a further dimension in versatility. A machine with these dual operating modes was designated by The Robbins Company as the 53R and was introduced into the Western Deep Level Mines, South Africa in 1984. The unit is powerful (200 hp) and compact (18,000 lbs., in a 10 ft x 4 ft 5 inch x 4 ft 6 inch package). This paper describes the design considerations for the new machine, provides field data from early trials, and looks briefly at its overall market and potential.

Jan 1, 1985

By Efstratios Karampinos, John Hadjigeorgiou, Philippe Morissette

"Ground support is a critical element in maintaining the stability of mining drives in deep and high stress mines. In challenging ground conditions, it is necessary to continuously explore ground support strategies that can control the resulting large deformations. It is an objective of mining operations to optimize the ground support by selecting appropriate systems at the time of installation of each reinforcement element. A successful ground support strategy will result in the use of a system that ensures both the structural and operational integrity of the excavations and mitigates the need for rehabilitation.Preliminary ground support design is often based on empirical observations and methods. Once a design is implemented, field trials, observations and in situ pull tests are used to fine tune or improve the design. Although not often employed during this process, numerical modelling can provide helpful insights into the impact of different ground support strategies. In this respect, it is possible to explore the use of multiple options before selecting the most promising ground support system for implementation in field trials. The challenges associated with the numerical modelling of rock support for mines have been described by Lorig and Varona (2013) and Potvin (2017). The employed numerical models should capture all potential failure modes of reinforcement throughout the mining sequence of the excavation. In particular, it is important to emulate the observed in situ ground support performance, as well as the influence of the installation sequence of the support. However, the time and expertise required for this type of modelling of ground support is often not available at mine sites. Even when the expertise is available, it requires a major time commitment and commitment of resources to set up, run and calibrate the sophisticated models capable of explicitly capturing the behavior of ground support.Rock reinforcement is an integral part of all ground support systems used in underground mines. Long, flexible tendons can reinforce the rock mass deeper into the walls and create a thicker reinforced shell around the underground excavation. This article focuses on the optimization of the cable-bolting strategy in squeezing conditions at the LaRonde Mine in Quebec, Canada by integrating the 3D distinct element method (DEM) in the design process. A calibrated numerical model is used to investigate a series of cable bolt configurations and provide recommendations for the ground support design."

Jan 4, 2018

By M. Sandin

According to the world bank1, the mining industry consumes up to 11 percent of global energy use. In comparison, 70 percent of mining projects from the six largest mining companies operate in water-stressed regions. To steer the direction of the process industries toward more sustainable practices, more than 40 governments have adopted a price on carbon. This measure includes additional taxes on the use of fossil fuels, trade programs, new standards for renewable energy, energy efficiency mandates, more stringent emissions regulation, carbon offsets, etc. This emphasis is also supported by investors shifting their priorities to reduce risk by focusing on long-term plans, including environmentally friendly operations. The metals and mining industry is at the core of the green energy mix and electrification of vehicles. This new trend creates an astronomical increase in demand for minerals. Under a 2-degree scenario, according to the latest analysis from the world bank, as new energy technologies continue to grow, it is expected that all minerals to double in demand, and the distribution of these materials will depend on their application. • Solar panels, will account for 87% of the aluminum demand, and more than 95% of silver • Wind turbines and geothermal plants will require 98% zinc and 64% titanium. • Solar and wind energy alone will demand more than 74% of the global supply of copper, and this is without considering wiring or other infrastructure to connect the grid • Battery storage accounts for 100% of the graphite and lithium demand. (Hund, 2020) • Other materials, such as nickel and steel, are also projected to more than double in demand as they are cross-technology minerals. These materials require a manufacturing process that is accountable for the emissions proper of the transformation process. It requires that these processes move from a hindsight mode focused on reporting to a forecasting mode based on run-time measurement of GHG emissions. This is a critical first step in companies realizing an economic return for doing the right thing for the environment and their communities.

Feb 1, 2023

By A. Mayton, W. Porter, A. O’Brien

In 2004, management at Unimin’s Gleason, TN operation began implementing ergonomic interventions specifically targeted to reduce risk of musculoskeletal injuries (MSIs). Together with corporate and site management, Unimin identified work site hazards and began to modify work practices/equipment. Some interventions were relatively simple and were implemented immediately. Others, like improvements to a mobile shredder, were more complex but were eventually resolved through a participatory approach with employees, management, manufacturers and NIOSH. This paper discusses ergonomic interventions that were successfully implemented using a bottom-up approach to reducing the risk of injury.

Jan 1, 2007

By R. F. Winkle

Shortly after World War II, considerable impetus was given to use of truck haulage in open pit mines by the manufacture of large off-highway trucks. Mine management was quick to utilize this more flexible approach to open pit operation and in the ensuing years much time and energy has been spent to improve the basic concept. Dramatic progress has been made in drilling, blasting, loading and hauling with much emphasis placed on equipment improvement. In general, haul roads in open pit mines and quarries have received rather perfunctory treatment in studies of surface mining operations. Their importance to the successful pit operation requires more than a brief sentence saying, "Good haul roads must be maintained." Haulage costs account for approximately one-third of total mining costs including general costs and about 90 percent of the total loading-haulage cycle time is consumed in travel, hence, good haul road planning, construction and maintenance are mandatory for a viable operation.

Jan 1, 1976

By Donald R. Williamson

Statistical studies at Cyprus Pima Mine indicate that samples from 22 blastholes are necessary for determining average copper grades, within a desired range of precision, for mine-model blocks by arithmetic averaging. The average number of holes in such blocks is 14. Many considerations show that more holes will not be drilled for sampling. A way to determine block grades more reliably than by" arithmetic averaging was sought. Thus far arithmetic averaging has proven to be the best procedure for the particular operation characteristics despite the small number of samples. It naturally follows that expenditure of great effort in sampling blasthole cuttings is unwise.

Jan 1, 1977

By Se-joon Kim, Jong-hwa Chun

"‘Gas hydrate’ is the common term for a solid material formed from the combination of various gases as ‘guest’ and water as ‘host’. A series of large-scale scientific drilling and coring programmes conducted since 2000 revealed that natural gas hydrate exists in a wide variety of accumulations in the sediments. The scaled-up onshore and offshore field production tests during the last decade show that gas production technology will be realized to make gas production from gas hydrates viable in the future, recognizing its potentials as one of the future sustainable energy resources.The total produced gas was approximately 470 m3 by the hot water circulation method over 6 days of operation in the permafrost-associated Mallik 2002 project in the Mackenzie Delta of Canada. In the Mallik 2007-2008 project, the gas was successfully produced stably by the depressurization method for 6 days, up to 13,000 m3 cumulatively. The depressurization method applied in the Mallik test was shown to be an effective way to produce gas from gas hydrates. The Alaska field trial to inject mixed gas of CO2 and N2 to exchange CH4 in 2012 was successfully done for the first time to produce maximum 1,270 m3 per day. A remarkable achievement was made by Japan when it completed its first offshore production test in the Eastern Nankai Trough, producing approximately 120,000 m3 of methane by the depressurization method over 6 days in March 2013. The technical challenges and scientific uncertainties obtained from Nankai Trough production test provide Korea with more considerations as to the aspects of well completion, reservoir formation and seafloor stability, sand control, flow assurance, environmental monitoring, and etc., due to the different geological setting and geomechanical properties of the Ulleung Basin in Korea."

Sep 1, 2014

By A. C. T. Bigg, Y. Kocak, N. K. Bodur

The Gumuskoy silver mine, owned by the Etibank, in the province of Kutahya, Turkey, has been operating since 1987 with primary, secondary and tertiary crushers, and two parallel single stage ball mill circuits. Continuing problems with crushing and feeding of the ore to the ball mills, because of the moisture retaining and sticky nature of the ore, prompted an investigation into the possibility of converting the grinding circuit to an autogenous or semiautogenous grinding circuit. This would remove the bottleneck associated with the secondary and tertiary crushing. At the same time the target feedrate is to be raised from 140 t/h to 175 t/h. This paper demonstrates the response of five ore types, and blends of ore types in an onsite pilot plant test program, and also suggests how the variations can be handled in a SAG mill/ball mill circuit incorporating just one of the present ball mills.

Jan 1, 2000

By W. W. Edgerton

Construction projects may be delivered under one contract package or multiple packages divided by discipline, geographic location, or other characteristics. Dividing the construction into contract bid packages is called contract packaging, and is a vital and strategic aspect of effectively delivering tunneling projects. The process of contract packaging considers many factors, including the type of project, location, and owner?s priorities. This paper describes the key facets of the contract packaging process used recently on several tunnel projects, reports, where possible, on the success of the process, and concludes with recommendations for applying this process to achieve the right contract package.

Jan 1, 2008

By Raymond W. Henn

The 32nd annual short course ?Grouting Fundamentals and Current Practice? was held at the Colorado School of Mines, June 13-17, 2011. The field demonstration portion of the course was conducted June 16 at Baski Inc.?s yard in Denver, CO. The full-scale field demonstration presents many types of drilling and grouting equipment in operation as well as numerous grouting methods per-formed under various field conditions. As part of the field demonstration, the class was shown the proportioning, mixing, testing and injection of various cement grout mixes into sand columns under controlled and recorded conditions. These sand column demonstrations have been conducted under controlled and measured conditions each year since 1999 as part of the short course. The sand column demonstrations were conducted prior to 1999, but with less quality control and minimal record keeping of the proportioning, mixing, testing, injection pressures and the final permeation results.

Jan 1, 2011

By G. A. Gamble

Fans used to ventilate subway, passenger rail and vehicular tunnels are similar to the fans used to ventilate underground mines. However, tunnel ventilation fan systems are typically designed to meet NFPA 130 or 502 standards, while mine ventilation fan systems must comply with the appropriate federal mine safety regulations. As a result, fan operation requirements and performance criteria, as well as typical fan and duct configurations differ significantly for tunnel and mine ventilation applications. Variations in environmental conditions in tunnels as compared to mines also result in differences in fan performance and material specifications. The need to enclose tunnel fans within building structures creates space restrictions impacting fan size selection that are not commonly encountered in mine fan installations, resulting in different approaches to selecting fans for the two types of tunnels. This paper discusses the various similarities and differences in design considerations for tunnel and mine ventilation fans.

Jan 1, 2009

By W. J. Spat

Political risk is an integral part of the mining business in northern Andean countries. Peru, Ecuador, Colombia and Venezuela all have a higher than average political risk compared with other South American countries. Successful operations require good political-risk information, a thorough political-risk-management plan and a strategy to deal with political-risk perception on the part of the investing public. Colombia is perceived as about the riskiest place in the world to do business. A selection of recent headlines reads: “Colombia on the brink” (Economist, 1998), “Colombia’s ship of state is sinking” (Insight on the News, 1998), or simply “Bad news” (US Catholic, 1998). The World’s Most Dangerous Places rates Colombia as “currently the most dangerous place in the Western Hemisphere, and perhaps the world” (Aral and Pelton,1998). And many prospective investors and analysts say to Greystar Resources: “Yes, we love your results, but Colombia?”

Jan 1, 2000