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By Michael Vitale, Lee W. Abramson, Daniel McMaster, Andrew J. Thompson

"Performing risk analyses on tunnel projects has become common place and on many projects it is required from an owner or regulatory perspective. After the project is planned, designed and constructed, the data concerning identified risks, assumptions, costs, probabilities and mitigations is generally long forgotten and buried in some file somewhere. A study was performed comparing predicted risks versus actual events on four recently constructed rock tunnel projects in New York, Ohio, Georgia and California. Probabilities and costs for selectively common risks on tunnel projects have been studied and re-evaluated. Conclusions are presented that can guide future projects and the veracity of the tunnel risk analyses performed. INTRODUCTION Tunneling is a risky business. More than ever, attention is being paid to the risks associated with tunneled facilities and implications on project or program cost and schedule. Questions about why tunneling projects notoriously exceed budget numbers abound. Evaluations in retrospect and going forward have focused on the wide breadth of inherent risks associated with tunneling. More and more, these risks are being identified, studied and managed to a higher degree. As more and more scrutiny pervades the industry, little value is being obtained and leveraged on future projects. The industry seems to be headed in a direction of making the same mistakes over and over. The notion of risk evaluation has been around for decades and received wide notoriety with the U.S. Space Program and ambitious projects in the energy industry such as hydropower and nuclear power in the 1960s and 1970s (Stewart and Melcher, 1997). This led to the evolution of tunnel risk analyses with more rigorous identification of the unique risks in tunneling projects impacting cost and schedule. As tunneling risks became more readily identified, more attention has been paid to the frequency and impact of the occurrences unique to tunneling (ITIG, 2012). Currently, few tunnel projects are being planned, designed or constructed without a formal risk register that identifies the risks, mitigates the risks and quantifies the probable impacts of risks that cannot be mitigated. In hind sight on many recent projects, events that brought projects to “its knees” were not addressed in risk assessments or were not dealt with to adequately mitigate the risk of these events."

Jan 1, 2016

By Eivind B. Jensen

Introduction Though temporarily shutdown due to the depressed economy, the Henderson mine is a large underground molybdenite producer, using a continuous panel-caving mining system. The location of the ore body requires access from the surface through three shafts, the collars of which are located about 3.15 km (10,350 ft) above sea level. At this altitude, normal temperatures are such that heat must be added to intake-ventilation air for about half of each year. This prevents ice from building up in the intake shafts, waterlines from freezing underground, employee discomfort, and equipment-related problems such as pneumatic rock drill icing and cold starting of diesel engines. Because of topographic and environmental constraints, the Henderson mill and concentrator are located 24 km (15 miles) from the mine, on the west side of the Continental Divide. All ore from the mine is transported to the mill by an electrified rail haulage system, with 15.4 km (9.6 miles) of the trip being underground through a double-track tunnel. A shaft at the midpoint of the tunnel exhausts air drawn from the mine and from the portal that is at an elevation of 2.7 km (8,950 ft). Intake air at the portal must be heated for part of the year to prevent ice buildup. Mine Ventilation System The mine ventilation system uses three sources of fresh air and two exhausts. The primary freshair intake is No. 3 shaft. It is concrete lined to a diameter of 7 m (23 ft) for a total depth of 698 m (2,291 ft). An airflow of 755 m3/s (1.6 mil¬lion cfm) is supplied to this shaft by two vane-axial 932-kW (1,250-hp) fans on the surface. The air is distributed within the mine by means of fresh-air distribution levels connected to production and development levels by raises. A secondary source of fresh air to the mine is provided by No. 2 shaft, the primary man and material access. This shaft is concrete lined to a diameter of 8.5 m (28 ft) for a total depth of 946 m (3,105 ft). Downcast airflow is induced by a pressure differential produced by the fans in the system such that net intake and exhaust volumes are equal. The No. 2 shaft flow of 165 m3/s (350,000 cfm) enters the mine network from the production and haulage levels. Exhaust air is moved from the various working levels through connecting raises to exhaust col¬lection levels that return it to No. 1 shaft. No. 1 shaft is the primary mine exhaust. It is concrete lined to a diameter of 7 m (23 ft) for a total depth of 788 m (2,584 ft). Three vane-axial 932-kW (1,250-hp) exhaust fans are located at the collar of No. 1 shaft, producing a flow of 850 m3/s (1.8 million cfm). In addition, an airflow of 71 m3/s (150,000 cfm) from the intake distribution level is exhausted via the haulage tunnel, by means of No. 4 shaft located midway in the tunnel. The main features of the mine ventilation network are summarized in Fig. 1. Ventilation Air-Heat Plants No. 3 Shaft In the early design phase of No. 3 shaft, it was recognized that air heating would be required to maintain underground temperatures above 0°C (32°F) during cold winters in the Colorado mountains. When the air reaches the mining

Jan 1, 1983

By Steven B. Van Kouteren

Added value is a term loosely used in the industry, but what exactly does it mean? What does it take to make a value-added product and more importantly how does a company maintain the value added to its products? Most people agree that value-added means the value of a mineral minus the cost to produce it. But what is misleading is that producing value added products does not necessarily guarantee the profitability of the products. In some cases firms that make "value-added" products are not very profitable. It is not only important to understand how to make a value-added product but also how competitive forces in the market can erode the value added. Therefore, when we look at value-added opportunities, we must understand how to obtain the value added and more importantly how to maintain the value. There are four major factors that limit a company's ability to add value to its products. This paper will examine these factors and will use the ground calcium carbonate and mica industries as examples.

Jan 1, 1990

By J. Philip Bromberg

Any effectuation of a viable program of air pollution control will' require a basic understanding of the chemistry of atmospheric processes, the fate and migration of SO2, and the ultimate health effects of the sulfur oxides themselves. The migration and ultimate fate of Sop discharged into the atmosphere will be discussed with particular emphasis on the various conflicting views and how these relate to our present emission control regulations. Our present lack of knowledge is a severe detriment, and consideration will be given to those particular areas where future research may best be directed to provide the answers to a number of perplexing questions.

Jan 1, 1976

By SONGHE WANG, YI XUE, PENG HOU, CAIHUI ZHU, XUANYE JIAO, Feng Gao

Coalbed methane development is an important way to effectively realize a source of clean energy and reduce emissions of carbon dioxide and other gases. However, due to the low permeability of coal seams, the development of coalbed methane in China has encountered substantial barriers. Protective layer mining can efficiently minimize in situ stress and increase coal seam permeability, thus improving gas drainage and avoiding gas disasters. This study analyzed the characteristics of gas migration and the change in permeability during the in situ stress releasing process through experiments and numerical simulation to study the gas drainage effect of a coal mine in an unloaded coal seam under specific geological conditions. First, a stress–strain-seepage coupled test of coal was carried out, and the evolution features of coal permeability during stress loading and unloading processes were investigated. Second, experimental results were used to develop a mathematical model of coal seepage under mining unloading conditions. Finally, a numerical model was developed based on the real geological conditions of the Wulan coal mine to explore the characteristics of in situ stress release and permeability evolution, as well as the gas drainage process in an unloaded coal seam. By combining protective layer mining and gas drainage technology, the risk of gas outburst is significantly reduced.

Oct 1, 2022

By Steve Kral

Worker safety is an issue that transcends industries, whether it be mining, construction, manufacturing or even general office work. In the mining industry, safety and training are particularly important because mining is a dangerous occupation. Throughout the years, federal and state safety regulations have been written and revised to keep up with the changing technologies. And mine operators have installed their own safety and training programs. They have come to realize that a safe and healthy workforce has positive effects on productivity and profitability —not to mention avoiding the high costs of injury-related absenteeism.

Jan 1, 2003

By Jon Y. Kaneshiro, Stephen J. Navin, Jerry Ostberg

In 1968, the U.S. Bureau of Reclamation awarded S.S. Mullen Construction of Seattle, the Intake Tunnel (488 m by 4 m diameter tunnel) and Pumping Plant No. 1. In1998, the Southern Nevada Water Authority awarded Lake Mead Constructors (Kiewit of Omaha) a parallel New Intake Tunnel (518 m long by 4.6 m diameter tunnel) and Pumping Plant. Both projects provide water to a thirsty Las Vegas. This paper presents a detailed comparison of the two intake tunnels in terms of grout takes and pressures, geologic mapping and rock quality, grout penetration beyond the excavation line, degree of fracture grouting, and groundwater inflow boundary considerations. The paper provides a comparison of grouting techniques and material developments then and now.

Jan 1, 2001

By JIACHENG XIE, Juanli Li, Wenyong Du, Tao Cui, Mengyao Dong, Pengfei Huo

The study proposes a dynamic path planning method for mining equipment based on spatial kinematics and real-time correction of coal-rock state identification. The method integrates real geological data and equipment operation information to improve the autonomous cutting of fully mechanized mining equipment.

May 1, 2023

By M. Boucraut

After stating the advantages of the magnetic roasting technique as applied to iron ores, the authors report on technological research by I R S I D * in the field of magnetic roasting in fluid-bed furnaces This investigation was conducted first on an experimental two stage fluid-bed furnace which processed permanently 100-200 kg/h of ore, then on a three stage fluid-bed furnace with 1-2 t/h working capacity and at last on a 250 t/day pilot furnace The specific features of the IRSID process comprise - on the one hand, using special burners in the roasting reactor thereby ensuring a high production rate of the furnace - on the other hand, using a heat-exchanger where the preheating and cooling stages of fluidized ore are associated, so as to allow an efficient and simple cooling of both roasted ore and waste gases flowing out of the roasting reactor, thereby supplying heat to the crude ore and combustion air for the reactor burners Starting in 1965 the operation of the 250 t/day pilot plant at the Bazailles mine gave IRSID the opportunity of improving the conveying appliances and adapting them to the process, while perfectly confirming the metallurgical results obtained under ideal laboratory conditions

Jan 1, 1968

By Anand Kumar, Debasis Deb, A. K. Mishra, M V. N. S. PRASAD.

In the Adriyala project, shield-leg pressure data from all shields and shearer location with time stamp from a mechanized longwall face are monitored and recorded in a surface computer. The data contain random noise due to power failure, leakage of legs, bad sensor readings, and other maintenance or geomechanical problems. An algorithm has been developed to detect mining cycle parameters such as setting and final pressures and duration of the cycle from these data for the analysis of periodic roof weighting phenomena. The intensities and persistence of periodic roof weighting are vital information for mine management to make judicious decisions on longwall operation.

By James W. Cooksley

This report concerns a seismic geophysical exploration program which was conducted 3 miles southeast of the Carlin Mine, in Lander County, about 18 miles north of Carlin, Nevada. A twelve-fold reflection seismic line was executed over a one-mile traverse in section 32, Township 35 North, Range 51 East. This study is part of an exploration pro- gram directed toward finding Carlin-type gold deposits which are concealed under younger alluvium and volcanics. The exploration objectives of this program are as follows: 1) measure the thickness of the younger, sedimentary and volcanic deposits which overlie the "productive rock sequence", 2) delineate the Roberts Mountains thrust fault, 3) investigate the origin of the geochemical anomalies present in the western portion of section 32.

Jan 1, 1985

By J. J. Fallon

The subject is "Mergers, Acquisitions and Divestitures in Industrial Minerals, but my remarks could also be applied to new product development, resource development and other new business development activities. At the kernel of the subject is due diligence in major decision-making, that is, where major money amounts and a large corporate commitment are at stake. The "due diligence" means how carefully we do our homework before making the decision. The homework or feasibility study addresses different parts of the decision. In the industrial minerals business the study seeks to uncover the pros and cons in: o The mineral reserves, quantity, quality, mineability, access, etc. o The environmental impact of mining, processing and transporting. o The economics of operations. o Financial aspects o Legal aspects o Many other aspects o And -oh yes! the marketing aspects.

Jan 1, 1990

By N. H. Coates

The Bureau of Mines designed, constructed, and operated an 18-inch- diameter, fluidized-bed combustor for highly caking coals to evaluate the method for possible application to power generation. In initial tests, combustion was carried on successfully, with carbon losses as low as 0.8 percent. Coal ash was not satisfactory as a bed material, but mullite proved to be acceptable. Overall heat-transfer coefficients from the bed (-20 + 50 mesh mullite) to a water-cooled tube were about 75 Btu/hr-ft2- °F.

Jan 1, 1970

The current understanding of the mechanics of rock fracturing during smooth blasting is largely empirical and qualitative due to an inability to model the dynamic process at the fundamental level. In order to overcome this difficulty, a numerical simulation of smooth blasting is performed using the Dynamic Lattice Network Model. This model is capable of simulating material inhomogeneities and the dynamic evolution of fragmentation at the micromechanical level. In this study, smooth blasting techniques are numerically analyzed to characterize the development of the damage rock zone during explosive fracturing.

Jan 1, 1995

By James E. Brewer

Procedure for approval by the U. S. Army Corps of Engineers of a new source of aggregate is in three phases. Phase 1 consists of an investigation of a quarry or proposed quarry by district geologist and laboratory geologist and/or petrographer. The quarry face or suitable outcrop is logged in detail or, if exposures are poor, cores may be taken to determine whether further investigations are warranted. Phase 2 consists of thorough laboratory testing. Cores and crushed material are subjected to a number of acceptance and quality tests for soundness, absorption, abrasion, reactivity, and other properties. Petrographic analysis is also made. Phase 3 is a physical and economic study of the site and involves determining quantity of stone avail- available, amount-and character of overburden, condition of haul roads and distance to rail shipping point, plant flow sheets and capacity, aggregate sizes produced, and approximate price of material at plant.

Jan 1, 1966

By A. Ghalambor

The objective of this investigation was to determine the sensitivity of three selected input parameters in the operational control of continuous bottom-fed thickeners used for the treatment of coal refuse slurries. The three variable parameters were "Feed Flow Rate," "Feed pH," and "Feed Solids Concentration." These three input parameters were studied under three polymeric conditions which were cationic polymer, anionic polymer, and a combination of cationic-anionic polymer. For each polymeric condition, two mathematical models were developed: one for overflow response, the other for underflow response. The combination polymers produced the best desired quality of overflow and underflow. For this polymeric condition, changes in the feed solids concentration was the most sensitive factor in the maintenance of the overflow quality, and the feed pH was the most sensitive factor for the maintenance of the underflow quality. The mathematical models generated a set of plots which would allow an operator to control and/or adjust any of the three variables to achieve optimum conditions.

Jan 1, 1989

By R. E. Pennington

My subject this morning is coal liquefaction technology. Actually, coal liquefaction involves a number of technologies in a very complex system. The first slide shows the major components of such a system with arrows to indicate appropriate flows. The components are the facilities for coal feed preparation and handling; the coal hydrogenation or base liquefaction section; facilities for product separation and recovery, and in addition, facilities for the production of hydrogen from coal-based sources. A very rough break- out of the investments involved in these areas is given at the bottom of the slide. Investment is spread about equally among the three areas of operations Another way of looking at it is that the investments in what might be called support facilities are of the same magnitude as the base investment in the hydrogen facilities. Therefore, it is appropriate in a discussion of coal liquefaction technology to treat it as a system composed of a number of technologies. The next slide lists the various functions in the feed preparation section along with an indication of technology status. Storage, crushing, grinding, drying of coal all have been in commercial practice for a number of years. The slurrying and pumping of coal at least in water slurries, is practiced commercially also. The heating of coal slurries in oil to high temperatures under pressure is not in commercial practice and development and testing is going on by a number of people in this area. Some rather complex phenomena occur when coal oil slurries are heated to high temperatures.

Jan 1, 1975

By Volkmar Niemitz

Approximately 30 miles east of Chicago on the southern shores of Lake Michigan stands Bethlehem Steel's newest fully integrated steelmaking facility - the billion dollar Burns Harbor plant. The initial phase of "green field" construction that began in 1963 was directed to the creation of high quality finishing facilities. In late 1964 the 160" plate mill came "on stream" followed closely by Sheet and Tin and Hot Strip facilities. Unit train shipments of slabs primarily from the Lackawanna plant located near Buffalo constituted the input materials for the new mills. In 1967 a hot metal facilities program was announced for Burns Harbor that at its completion would make the plant fully integrated. Incorporated within the program were: 1. A new high performance 50" x 96" slabbing mill complete with a battery of soaking pits. 2. A two vessel Basic Oxygen Furnace Shop. 3. (1) battery of 6 meter high Coke Ovens with attendant coal handling facilities. 4. A 3800 feet long vessel loading & unloading dock. 5. The first conveyor belt fed Blast Furnace in the United States. 6. An extensive materials handling system for receiving, stocking and reclaiming from storage the raw materials for the Blast Furnace and Coke Ovens operation. The intent of this paper is to provide a detailed description of the functions and components of the materials handling system noted above.

Jan 1, 1970

By Norman Miskelly

Role of CRIRSCO CRIRSCO has an advisory and hopefully influential role in International Mineral Resource/Reserve Reporting Standards CRIRSCO also has a broad educational role CRIRSCO does NOT have a negotiating role CRIRSCO does NOT have a regulatory role

Jan 1, 2003

By V. Kecojevic

Environmental and economic costs related to equipment fuel consumption and carbon dioxide (CO2) emission present a substantial challenge to the mining industry. Haul trucks are an integral part of the overall surface mining system and they consume a significant quantity of fuel. Consequently, they produce a significant amount of CO2. The objective of this research is to (i) establish a mathematical relationship among a truck?s fuel consumption, power and engine load factors and (ii) determine the amount of a truck?s CO2 emission and the associated cost that may arise from potential CO2 legislation. In order to achieve these objectives, the authors have considered original equipment manufacturer (OEM) haul trucks, which are commonly used in surface mining operations. The research presented here may be used by mining professionals to help determine the cost and environmental burden of the trucks? application and efficiently manage energy consumption.

Jan 1, 2010