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By D. B. Desai, J. T. Waggoner, J. S. Hill, R. R. Redd, S. J. Klein

The 13 km (8 mile) long Riverside Badlands Tunnel is planned for construction starting in 1998. Extensive geotechnical investigations indicate that the 3.7 m (12 ft) finished diameter tunnel will be excavated through soft ground, weak sedimentary rocks, and heavily fractured metamorphic rocks. Nearly 80 percent of the tunnel will be excavated beneath the groundwater level. Tunneling conditions are expected to range from raveling and over-stressed in the sedimentary rocks, to blocky and seamy/crushed with some squeezing in the metamorphic rocks. Two alluvium reaches will require dewatering. The variable and interspersed ground conditions are expected to be a key factor in selection of tunneling methods, equipment, and initial support.

Jan 1, 1997

By Photios G. Ioannou, Guillermo F. Salazar, Herbert H. Einstein, Yeong W. Kim

The MIT tunneling group has developed, over the past decade, a number of decision support tools for the geologist and engineer, planner and designer, owner and contractor involved in underground construction. These computer based tools can be used in the planning and exploration stage of a project, in predesign and design, in construction planning and during construction. Tasks as different as optimizing information collection during exploration and during construction, as selecting major design alternatives in predesign and modifying design during construction, as providing cost and time estimation and considering social and physical environmental constraints, can be handled. Output can be in the form desired by the user ranging from geologic profiles (cross sections) to management reports.

Jan 1, 1987

By J. R. Patts, L. D. Patts, S. J. Janisko, T. Barone

"Controlling float coal dust in underground coal mines before dispersal into the general airstream can reduce the risk of mine explosions while potentially achieving a more efficient and effective use of rock dust. A prototype, flooded-bed scrubber was evaluated for float coal dust control in the return of a continuous miner section. The scrubber was installed in line between the ventilation tubing and an exhausting auxiliary fan. Airborne and deposited dust mass measurements were collected over a period of three days at set distances from the fan exhaust to assess the changes in float coal dust levels in the return due to the operation of the scrubber. Mass-based measurements were collected on a per-cut basis and were normalized per foot of advance by the continuous miner. Results show that average float coal dust levels measured under baseline conditions were reduced by over 91% when operating the scrubber. INTRODUCTION In 2012, underground mining in the United States produced over 342 million tons of coal [EIA 2013]. During the cutting, crushing, and transport of this coal, dust is generated and can be entrained in the air ventilating the mine. Title 30 Code of Federal Regulations Part 75.400-1 (30 CFR§ 75.400-1) defines float coal dust as particles of coal that can pass a No. 200 sieve. These coal particles can be carried by the ventilating air into return entries before settling onto mine surfaces [NIOSH 2006]. If this float coal dust becomes re-entrained into the airstream, it can propagate an explosion throughout mine workings [Harris et al. 2010]. Application of rock dust in underground coal mines is required by Federal regulation as a means of preventing the propagation of explosions by float coal dust. In order to meet Title 30 Code of Federal Regulations Part 75.403 (30 CFR § 75.403), 80% incombustible content must be maintained in the composition of dust deposited in mine entries [76 Fed. Reg. 35968 (2011)]. This fraction of incombustible content is increased if elevated levels of methane are present. In order to maintain the required incombustible content, frequent or constant application of rock dust is undertaken by mine operators. Title 30 Code of Federal Regulations Part 75.2 (30 CFR § 75.2) defines the properties of the rock dust that must be used by mine operators."

Jan 1, 2015

By Bernd Hagenah, Petr Pospisil, Colin Santangelo

This paper explores the profound implications of high-speed train operation on tunnel planning, specifically investigating ongoing high-speed rail projects in California and Texas. The paper delves into the crucial considerations for designing high-speed rail tunnels, including selecting tunnel sections based on aerodynamic factors, which impacttraction power requirements and pressure comfort. The paper also examines the need for emergency stations, maintenance access, and comprehensive safety and rescue concepts to address train incidents. Drawing from international high-speed rail projects, it shares valuable experiences and lessons learned to promote efficient and secure tunnel designs for high-speed train operations.

Jun 23, 2024

By M. W. Chanda

This paper presents the development of a rock-creep measuring apparatus using air as the initial pressure source. Servo-controlled machines can and have been used for time-dependent property tests. However, the long-term nature of some tests makes essential the complete independence of stress-maintaining equipment from main power sources or continuously running hydraulic pumps. The main objective of this paper is the development of a creep testing machine that is free from interference arising through power supply interruptions or mechanical maintenance normally associated with many compression testing machines. To achieve this, a compressed-air power source was used to drive a compression ram. A few trial results obtained and analyzed using the transient creep law are in reasonable agreement with the general creep law.

Jan 1, 1993

By Raj K. Rajamani, M. K. Abd El-Rehman

The planetary mill is very much suited for the ultra-fine grinding of mineral fillers. Ultra-fine grinding here refers to grinding powders to a size range 5-1 0 rnicrons. Such powders enhance the quality of the final product. The operation of a specially built planetary mill is described. It is shown that a target size of 5 rnicrons can be reached in a few hours using the dual drive planetary mill. A centrifugal field of 37G is generated by the gyration arm of the mill. The design allows the desired setting of canister critical speed. The ultra-fine grinding of alumina, titanium dioxide, hematite, magnetite, kaolin and silicon carbide are described. Also, the continuous operation of the mill is shown.

Jan 1, 2003

By Drupad B. Desai, James G. Gallanes

A key component of the Inland Feeder Project is the Riverside Badlands Tunnel, a7.9-mile stretch subjected to high internal and external hydraulic pressures passing beneath highly eroded hills in a semi rural environment. The tunnel presented significant design and management challenges to the project team. This paper describes the formula for project success used to manage the design of this complex pressure tunnel, from team member selection to the completion of all contract documents, on schedule and below budget. The project team dealt with sensitive regional and local community issues and won the trust of the community. The team included participation by senior management and recognized experts from inception to finish. The team worked diligently to build quality into design and adopted a claims avoidance approach to management and preparation of documents.

Jan 1, 1997

By L. Rainey, W. E. Wallace, B. L. Razzaboni, P. Bolsaitis, V. Vallyathan

The hemolytic activity of milligram-sized mineral dust samples from coal mines collected in personal dust samplers were measured by a modified Harington assay method which increases the sensitivity of the technique. Measurements were conducted on a large number of samples from different mines characterized for gravimetric quartz content and the relative bulk concentration of common contaminants (Al,Ca,Fe). The results of these measurements were compared to the hemolytic activity of pure quartz and of mineral samples obtained from roof-bolter dust boxes of two coal mines. No correlation could be established between hemolytic activity and the compositional variables tested. The results suggest that the distribution of minerals among individual particles and the surface characteristics of particles, rather than the bulk concentration, determine the hemolytic activity of respirable mine dusts.

Jan 1, 1991

By R. L. Grayson, G. Mishra

Introduction Many old underground mines have been developed extensively into reserves requiring large numbers of workers to maintain and rehabilitate lengthy track haulages and/or belt conveyor systems. Often, large numbers of fans are required to maintain minimal airflows in areas where poor conditions and huge leakages prevail. Problems that beset one such coal mine and projects undertaken to restore it to potential profitability are presented. Brief history The Vesta No. 5 mine was opened in 1908. Drift development began near the Monongahela River, which was the primary avenue for shipping metallurgical coal to coke ovens in Pittsburgh. Over the ensuing 75 years, the main haulage entries were developed a distance of 16.1 km (10 miles) to the present mining area. Track haulage was used to transport coal from working sections to the river loading facility. As haulage distance and areas of high water influx increased, management decided, in 1973, to construct an underground conveyor belt system. The project spanned 36 months and culminated in a system of 22 flights, ranging from 205.7 to 1767.8 m (675 to 5800 ft) long. Six intake and eight return entries were developed as the mains were advanced. These entries provided adequate ventilating capacity over the years, but as extensive gob areas progressed and roof conditions deteriorated, the entries became inaccessible and more resistant to airflow. By 1981, five fans were being used to circulate 943.9 m3/s (555.5 cfm) of air through the mine. An average of 6440 t (7100 st) were produced from 20.8 continuous miner unit shifts and 2.7 longwall unit shifts each day in 1981. The ratio of support to production personnel was 1.94. To maintain the outby 16.1 km (10 miles) of haulage, 110 personnel were used. The average cost per ton was $43.54 ($39.58 per st), resulting in excessive bottom-line losses. The mine possessed a rather promising reserve, mostly in lease, of good quality, medium-sulfur metallurgical coal, but it also had a number of formidable operating problems. Operating problems Contributing factors toward relatively low productivity and high costs were the conditions of the track haulage, conveyor, and ventilation systems. Productivity was affected greatly by downtime associated with the conveyor system, which lacked adequate access for making splices or other repairs. Many areas within the conveyor belt entry itself required more

Jan 1, 1988

By E. S. Peterson, M. K. Harrup, K. A. Dolbeare, J. E. Wey

Efficient methods for the removal of copper from heap-leach solutions without mobile organic phases are a current mining industry need. To satisfy this need, a selective, high-capacity, durable solid material is required. The Idaho National Engineering and Environmental Laboratory (INEEL) developed a set of materials based on current solvent-extraction chelates that provide selective copper concentration in the presence of high concentrations of iron. In contrast to conventional solvent extractions, the author's strategy anchors the chelators to a nonpolymeric solid substrate through the use of a custom-designed linker molecule. The fundamental synthetic routes to these materials have already been established, and attachment to the solid surfaces have been achieved in an efficient manner. The author's continuing research is focused on the optimization of the synthetic pathways to these solid materials and the evaluation of their copper-capturing capabilities.

Jan 1, 2003

By P. E. Nielsen, T. L. Loga, B. B. Mauko

A numerical model is presented which simulates the dynamic fracturing process for a circular geometry fracture in a uniform stress medium. The dependence of crack aperture and net pressure in the crack upon various dominant parameters of the fracturing process is discussed. An analysis of a 75% nitrogen foam fracture in a coal seam at 5600 feet (1707 m) is also presented. The analysis is based upon the discussed parametric trends, the job records of treatment parameters, and a Nolte plot of net downhole pressure. It is interpreted that fracturing with water, in pre-foam fracture pump tests, resulted in significant fracture height growth. However, the subsequent foam fracture had reduced height growth due to the high effective viscosity of the foam and due to the higher magnitudes of elastic modulus and stress in the bounding rock strata with respect to the coal.

Jan 1, 1986

By R. L. Grayson

In 1995, the United States Congress abolished the Bureau of Mines in the US Department of Interior. But Congress preserved the safety and health research functions being performed at the Pittsburgh and Spokane Research Centers. These functions were transitionally housed in the US Department of Energy before permanently merging with the National Institute for Occupational Safety and Health (NIOSH), Department of Health and Human Services, in October 1996. Since the rnerger of the former Bureau of Mines with NIOSH, there has been an active evaluation of ongoing research activities, significant interaction with stakeholders, and the development of a process leading to "data-informed" priority setting. This paper reviews the current surveillance information concerning the level of injury and disease from mining work and discusses how research priorities are evolving to improve the contribution of research to the prevention of injury and disease.

Jan 1, 2000

By Frank T. Wheby, Edward M. Cikanek

A computer performs all logic and computations customarily done by hand in preparation of engineers' estimates or contractors' bids on tunnel-shaft systems. The program described is based on construction methods, work forces and equipment selections corresponding to the current state-of-the-art of rock, soft ground and cut-and-cover tunneling. The program contains logic to permit estimates of cost of complicated tunnel-shaft systems; it is not necessary to input quantities, as the program calculates those from the tunnel design that is internally generated. In any estimate, the program bases its cost computation on user-input requirements and site conditions, such as tunnel shape and size, shaft depth, ground characteristics, construction methods, and other factors. To provide great flexibility, the user of the program is provided with options for accepting designs built into the program or overriding these designs by his own inputs. An illustrative example is presented.

Jan 1, 1974

By Raj K. Rajamani, Ilesh M. Shah

Maintaining pH, a routine requirement in many industrial processes, is by no means trivial. The control is troublesome because of the inherent nonlinearity and frequently changing process dynamics. Many researchers in the past have investigated advanced on-line estimation and/or adaptive control techniques to overcome these difficulties. Most methods require the development of a complex mathematical model. The present work deals with the use of a simple and elegant method for pH control, based on the use of fuzzy logic. First, a standard fuzzy-logic controller is discussed, followed by a self-organizing controller. The latter algorithm generates a set of rules based on observation of the process. Thus it is a learning algorithm. The development and application of the algorithms to a laboratory acid-base neutralization experiment are presented. This elegant technique is powerful and deserves attention in mineral pro- cessing.

Jan 1, 1990

By S. S. Hsieh

As part of a program to address the long-term need to ensure adequate supplies of domestic phosphate raw materials, the Tennessee Valley Authority (TVA) has conducted considerable research on dolomitic phosphate rock beneficiation. The discovery that alkyl diphosphonic acids act as phosphate mineral depressants led to the development of several processes involving a carbonate flotation step for the effective beneficiation of these problem ores. Most recently, a partial deoiling process in which the reagent consumption is greatly reduced has been developed. The reduction is achieved because part of the initial feed is beneficiated without passing through the separate carbonate flotation step. Using this method, a phosphate product containing 30.6-30.9% P2O5 and 0.7-0.8% MgO was obtained from a Florida dolomitic phosphate pebble that contained about 23% P2O5 and 2.0% MgO. The P205 recovery was 80.8-86.5%.

Jan 1, 1991

By Paul H. Lu

This paper proposes a novel method, "integrity factor approach," of mine-pillar stability evaluation based on in situ triaxial-loading measurement. The pillar integrity factor is defined as the quotient resulting from division of integrated total pillar strength across the critical dimension by the integrated total pillar load across the same dimension. The integrity factor is dynamic, while the conventional safety factor is static. With this approach, the pillar stability can be evaluated at any stage of mining progress during panel operation. It automatically considers the progressive failure of the pillar and post-failure strength without the need to clearly define the boundary between yielded and intact zones of the pillar. Based on two case studies, the integrity factor approach is shown to be a practical, effective technique for evaluating stability of conventionally designed pillars. It is suggested that a more realistic estimate of in situ pillar strength could be made based on the combination of in situ triaxial-loading measurements and laboratory true triaxial compression tests, rather than through the traditional combination of biaxial-loading measurements and conventional triaxial compression tests.

Jan 1, 1986

By Flavio Moreira Ferreira

In mining industry, one of the simplest methods to smooth the standard deviation of a given ore controlled property is to build longitudinal blending piles. The effect of homogeneization is obtained due to the fact that an entire cross-section of the pile is reclaimed at each time. The variance of the pile output is the sum of the internal cross-section slice variance plus the reclaimed slice variance. While the first term is a tipical short-term parameter and is absorbed by the process, the second one may be or may not be absorbed. The goal of designing blending piles is to minimize the reclaimed slice variance. Conditional Simulation as described in this paper, is an alternative method to do it. It is devised to design longitudinal blending piles, taking into consideration economical, geometrical and statistical parameters of the ore to be blended, in order to estimate the resulting effect. It presents advantages in relation to other methods for its adaptability and flexibility in simulating pile performances.

Jan 1, 1992

By D. Gu

Breakage of rock by machine is one of the major methods of excavation. With the development of modern engineering techniques, the advantages of using this method have become even greater. Improving efficiency and reducing the cost of rock breakage is the main goal of mechanizing the rock-breaking operation. For a given stratum, the efficiency of a machine excavation depends, to a large extent, on the design and method of application of the tools used. In a planetary cutter head, the subcutter heads move like planets around the main drive shaft. The general structure of the cutter head is shown in Fig. 1. As shown in this illustration, the main drive shaft (1-1) is connected to the tie bar (1) and, thereby, to a gear(5) that meshes with a fixed-gear ring(2). The subcutter head (4) is rigidly connected to the gear (5) by the subcutter-head axis (2-2). When the main drive shaft (1-1) rotates, the subcutter head (4) rotates around the axis (2-2), under the action of the tie bar and with the help of sleeve pipe (3).At the same time, axis (2-2) also rotates around the main shaft (1-1). As shown in Fig 1, is the angle between the main shaft and the subcutter-head axis.

Jan 1, 1995

By Ted M. Noskiewicz, James A. Ramsay

INTRODUCTION During the various stages of an underground project from inception through design and construction, probably the single factor of most interest and concern is the nature of the ground. The ground conditions more than any other item govern costs and feasibility; and although the methods available for assessing the ground have become increasingly reliable during the past thirty years, it is still very difficult in many cases to predict the behaviour of soil and rock during and after excavation. To help in this ground evaluation process, we have frequently supplemented the boring program with one or more large diameter inspection holes; and during the past eighteen years, seventeen of these holes have been constructed on tunnel projects which we have designed. There are references in the literature to similar inspection holes (1); however, as far as we are aware, no detailed description of them has been published. The behaviour of soil or rock during and after excavation and the effect of ground water on tunneling operations are of vital interest to tunnel designers and contractors. A comprehensive geotechnical investigation is therefore among the early and most important tasks carried out on a tunnel project and the backbone of every geotechnical investigation is the boring program. A series of borings, typically 50 to 100 mm (21 to 4 in) diameter, are drilled from which soil samples or rock core are recovered and the ground water observed.

Jan 1, 1979

By K. P. Unrug, E. Thompson, S. Nandy

The method of coal pillar design involves primarily two aspects: the geometry of the pillar and the strength of the coal. However, the strength of the coal has to be emphasized with respect to the entire pillar dimension rather than isolated strength values of coal samples taken and measured from different locations. As of now, the presently applied pillar design systems do not specify clearly what the coal sample strength really represents. The intention of this paper is to introduce the concept of seam strength as opposed to the current practice of using coal strength as a prime design criteria in the formulation of pillar calculations. Seams are most often composed of multiple layers of coal, partings, and bone in various configurations, changing within the vertical section of the seam even in relatively close locations. The difference in strength between the weakest and strongest component of the coal seam could be as much as five times or more. An experimental approach based on multiple uniaxial compressive strength tests performed on coal samples from the Coalburg and Warfield seams from eastern Kentucky was undertaken. Analysis of the results led to the conclusion that for pillar dimension calculations, both the weighted mean of the seam strength and the strength of the weakest stratum should be considered, rather than the relatively vague aspect of coal strength. The design of pillar dimensions based on the aforemen¬tioned criteria should assure a more realistic design performance.

Jan 1, 1987