Search Documents

By Karel SPIRKO

The one-dimensional mathematical model of unsteady-state heat conduction through semi-infinite homogeneous and isotropic airway walls with convective heat and moisture transfer between their wet or dry naked surfaces and mine air with time variable temperature and humidity has been developed on the basis of introduction of acceptable simplifications of description of heat and moisture transfer between rock mass and mine air. The analytical solutions for computation of the temperature distribution and surface temperature of the airway walls and floor and for calculation of water vapour pressure near the wet surfaces at given time are obtained by means of the model presented. The presented solutions are derived for general conditions and they could be easily adapted to the actual ones. Results of the model represent basis for balancing heat and moisture transfer between mine air and its surrounding in deep mines under time variable temperature and humidity of the air and enable us to solve complicated dynamic changes of mine air temperature and humidity in an airway system by relatively simple mathematical tools. INTRODUCTION The importance of unfavourable influences and the costs of condition arrangements increases with mine depth. Precision demands on the methods which predict the environmental condition changes and by which it is possible to optimize condition arragements are still increasing. Environmental conditions in deep mines are determined especially by flow velocity, barometric pressure, temperature, and humidity of mine air. Therefore new and more exact mathematical models of mine air flow through airway system and those of heat and moisture transfer between mine air and individual important sources of heat and moisture are developed. The paper presented deals with description and solution of problems of heat and moisture transfer between mine air and airway walls as the rock mass is one of the important heat and moisture sources in deep mines. There are several different approaches to the problem. In some models the moisture transfer between mine air and airway walls is not considered at all. In other models the moisture transfer is described only by certain empirical coefficients. Simultaneous heat and moisture transfer is described seldom. This paper tries to describe in a simple way simultaneous convective heat- and mass-transfer processes taking place on wet naked surface of airway walls by means of corresponding

Jan 1, 1993

By D. H. Carlson, J. H. Johnson, C. F. Renders

Research was conducted at a western coal mine on a wide variety of underground mining vehicles to develop testing procedures for portable instrumentation monitoring of tailpipe concentrations of diesel particulate matter (DPM), carbon dioxide (CO2) carbon monoxide (CO) and nitric oxide (NO). DPM was measured using the Emissions Measurement Appa¬ratus (EMA) developed by Michigan Technological University (MTU), and an ECOM-KL five-gas analyzer was used to measure gaseous tailpipe concentrations. Baseline concentrations of the tailpipe pollutants were measured using vehicle systems to load the engine. Concentrations before and after the water scrubber were measured and water scrubber efficiencies were estimated by calculation. Field measurement procedures were established. Heavy-duty vehicles with automatic transmissions were loaded using the torque converter to stall the engine. Consistent engine loading for light-duty vehicles with manual transmissions involved placing the transmission in neutral and adjusting the throttle to maintain a constant engine speed of 2,500 rpm. Tailpipe CO2 concentrations for Caterpillar 3306 and 3304 engines were compared to laboratory CO2 data from Caterpillar and MSHA to help determine if engine settings were correctly adjusted for operation at high altitudes. (Perfect agreement between the mine vehicle tailpipe and laboratory measurements would not be expected because of the differences in the test conditions.) DPM concentrations for light-duty vehicles ranged from about 20 to 160 mg/m3, and one light-duty vehicle averaged near 1,000 mg/m3. DPM concentrations for heavy-duty vehicles ranged from about 55 to 200 mg/m3. Widely ranging DPM concentrations for a particular vehicle type reflect the state of maintenance, fuel rate settings and different engine loading procedures as well as differences between samples collected upstream and downstream of the waterscrubber. The calculated DPM removal efficiencies due to the water scrubber varied considerably between vehicles, ranging from 13% to 51%. Calculations indicate that, under worst-case conditions, very large reductions in DPM may be required to meet the proposed DPM PEL of 0.15 mg/m3, even on vehicles with water scrubbers. In-mine ambient air studies, which are needed to actually measure the impact of the tailpipe concentrations on the work environment and the effect of mine ventilation on the dilution of DPM were not done in this first set of tests.

Jan 1, 2000

By Frank A. Aplan, Barbara J. Arnold

INTRODUCTION Coal flotation is a fine cleaning process usually present in all but the older preparation plants. It is typically used to clean either the -28 mesh (-500 pm) or - 100 mesh (- 150 pm) raw coal fines, and it is the only commonly used preparation method that can effectively recover coal particles finer than, say, -200 mesh (74 pm). To place coal flotation into its proper context, it should be noted that the bulk of the raw coal sent to preparation plants is treated by gravity concentration. On a worldwide basis, from 0 to 40% of the raw feed to a preparation plant is treated by flotation, while in the US only about 10% of the raw coal feed is floated. Roughly, 50% of US preparation plants use flotation to process at least a portion of the raw coal feed, although most of the newer plants incorporate flotation into their flowsheet. Historically, the process has only been used to treat the raw coal fines naturally occurring after mining and a minimal amount of crushing at the preparation plant. This is in sharp contrast to ore flotation where, typically, the entire tonnage is first ground and then floated. As a consequence, of the approximately 500 Mt of raw coal treated by preparation in the US yearly, it is estimated that only about 40 Mt are sent to the flotation circuits (producing -30 Mt of clean product).'O1 This small tonnage compares with about 400 Mt of ores treated annually in the US by flotation. By analogy to ore flotation, where it is an effective, large tonnage, low cost, easy to operate process, its potential in coal preparation should be great. Reasons why it has not achieved a greater potential in coal preparation have been attributed by Aplan 102 to: 1. Indifferent results in removing sulfur and ash. 2. Difficulty in floating low rank and oxidized coals. 3. Inability to make clean separations with the finer sizes. 4.Inability to clean slurries with a high percentage of clay. 5. Problems with water chemistry. 6. Competition with effective, gravity coarse-cleaning methods. 7. Low value of coal historically. 8. Dewatering problems. 9. Transportation and storage problems with coal fines. 10. Marketing problems with coal fines. 11. Inadequate attention to the process in the plant. 12. Inefficient use of capital and operating monies. Inadequate attention to procedures, machines, and processes.

Jan 1, 1991

By David Smith, Bernie Martin

The Queens Bored Tunnels consist of 11,000 feet of 19'-6" inside diameter tunnels mined through rock, mixed face and dense glacial till, constructed with bolted gasketed one pass reinforced concrete liner. The tunnels are to be excavated with a pressurized face TBM, either EPB or slurry. The construction of the tunnels will require ground stabilization in the mixed face area, instrumentation and monitoring of railway infrastructure, underpinning of bridges, relocation and protection of utilities, demolition of some industrial buildings, construction of open-cut approach tunnels and emergency exits and vent plants. The purpose of this paper is to describe the scope of work, the suggested methodology and the proposed construction schedule.

Jan 1, 2005

"Above ground, elevated belt conveyors that span more than 200 m (656 ft) between support points can cross valleys, rivers, forests and buildings with a minimal footprint. The cable bridge conveyor (CBC) is a new type of suspension bridge based belt conveyor system that has long spans between support points. It combines a typical belt conveyor and an improved simple suspension bridge to form a conveyor bridge. The improved simple suspension bridge places a widened bridge deck directly on suspended cables, without the need for high truss towers. The benefits include reduced cost and increase aerodynamic stability compared to conventional suspension bridges. The CBC’s compatibility with current belt conveyors allows versatility in application.A belt conveyor is a ubiquitous material handling system. Conveyors can be placed directly on ground or elevated above ground by support structures. Considerations of cost, design, environment, civil work, safety and process requirements are all factors in choosing the ground-based or elevated conveyors (Zhang, 2014). The ground-based conveyor has the lowest structural cost when the conveyor is placed on an existing road. Maintenance access is easy and straightforward. Compared to the groundbased conveyor, the elevated conveyor can cross existing buildings and structures, give passage to traffic beneath the conveyor, has a smaller footprint and requires less civil work to pass mountainous areas. The drawback of the elevated conveyor is higher structural cost, which can be compared with savings in civil work and other benefits. Conventional elevated conveyors are supported by rigid truss-type structures, with a typical span of 15 to 25 m (50 to 82 ft) between concrete support bents or steel trestles. Triangular truss, using steel pipes instead of hot rolled steel sections, is more efficient. The typical span of a triangular truss-supported conveyor is around 30 to 40 m (100 to 130 ft), while the weight is about 10 percent less than conventional box truss with a shorter span (Jennings, 2013).Long-span elevated structures based on suspension bridge is another step forward in increasing the distance between support bents, reaching 100 to 400 m (330 to 1,312 ft) and beyond. The wide distance between the support points of an elevated conveyor offers unique benefits. The conveyor can cross rivers, valleys, highways, forests and other obstacles with minimal footprint and reduced civil work. The versatility from long-span conveyors makes bulk material transportation over previously impossible terrains now a feasible option."

Jan 1, 2014

By D. M. Wagner, G. Biggs, M. Osmundson, C. J. Twaroski

Potential air emission impacts to federal Class I areas from distant sources are receiving increasing scrutiny by federal land managers (FLMs). This paper provides summary results of the impact analyses conducted for FLMs and PSD permitting of a proposed expansion for a taconite processing facility. Results from air quality increment, acid deposition, mercury deposition, and visibility analyses for Class I areas located 50 to 162 km from the facility showed the project would meet the respective regulatory and guideline values for the specific analyses. During the course of the air quality analyses, potential new requirements from the FLMs’ Air Quality Related Values Workgroup (FLAG) efforts and USEPA’s Regional Haze Program were brought into the PSD discussions. The implications for these future guidelines and regulations as they may affect future expansions at other mineral processing facilities are also discussed.

Jan 1, 2001

By William R. Yernberg

SME’s Arizona Conference was held at the Doubletree Hotel at Reid Park in Tucson on Dec. 5and 6, 2004. The annual conference is organized by the Arizona Conference Board of Directors, which represents SME sections in Arizona and adjacent areas. The conference provides an opportunity for individuals and corporations associated with mining in the region to get together each year to discuss the status of the industry. The meeting featured a keynote address and more than30 technical papers. Two years ago, the U.S. copper industry was facing on a run for two years now,” and “both precious metal and base metal prices are going up.” The increases in metal prices were attributed to development in China and other Asian countries. “With a population of 1.6 billion, China has recently created 80 million jobs,” said Silver.

Jan 1, 2005

By D. J. Englund, R. A. Davis

"A three-dimensional CFD model of a straight grate furnace for indurating iron-oxide pellets was developed for exploring conditions of furnace operation for fluid flow, heat transfer and reactions. The model includes reactions for natural gas combustion in the gas phase and calcination and magnetite oxidation as well as drying in the pellet bed. The performance of the model was investigated with a series of pellet production rates that included adjustments to the fuel rates to achieve proper induration temperatures in the pellet bed. The model may be used to discover opportunities for process improvement.IntroductionIron oxide pellets are a feedstock to blast furnaces for iron making. Pellets require physical strength characteristics needed to maintain their integrity during storage, handling, transportation and smelting. Pellets are produced from iron ore in a series of mineral processing operations that form wet green balls from slurries of iron-ore concentrate with binders, such as bentonite, and possibly fluxing-agents such as limestone and dolomite. The green balls are dried, fired at high temperature, and then cooled in an induration furnace to achieve the strength and chemical composition required for efficient reduction and slag separation in blast furnaces. Induration furnaces are generally straight grates or grate-kilncooler configurations. These furnaces operate with pellet beds passing through a series of temperature zones to control drying and chemical reactions in the bed.Process air passes through the zones in an overall counter flow direction to the pellets for efficient heat transfer and energy recovery from the cooling stage. Consequently, the zone conditions and the overall furnace performance are highly coupled. Thus, it becomes challenging to predict how changes to any single zone may affect the rest of the furnace. To gain a better understanding of machine performance and coupling, a three-dimensional, steady-state model of a complete straight grate induration furnace was created using computational fluid dynamics (CFD)."

Jan 1, 2015

By Alper Kirmaci, Taghi Sherizadeh, Kutay E. Karadeniz, Dogukan Guner, Samuel Nowak

Injuries and fatalities resulting from roof falls are still a major concern in U.S. coal mines, and many researchers are focused on developing meaningful approaches to minimize this hazard. In the United States, coal mine roofs can vary widely in composition, geometry, and inherent heterogeneity, leading to a wide array of different roof fall failure types. Researchers frequently employ numerical modeling tools to reproduce this physical phenomenon and provide key guides to engineers regarding roof conditions and control as long as the input data and constitutive relations are appropriately selected. Simulating such complexity requires expertise and constitutive models that adequately simulate roof behaviors. However, the currently available constitutive models have shortcomings in capturing some of the roof fall failure types common in underground coal mines, such as guttering. A new constitutive model is developed to address the shortcomings of constitutive models commonly used for coal roof stability analysis. The constitutive model developed in this study combines the anisotropic-elasticity and nonlinear strain-softening responses. In addition, the developed constitutive model can simulate up to three different joint sets implicitly, allowing for use in both continuum and discontinuum settings, and can be used in both Lagrangian finite-volume and distinct element method codes of Itasca. First, the mathematical expressions of the model are provided. Afterward, the validation phase of the developed model that covers comparisons with analytical solutions and those of existing models (e.g., anisotropic elasticity, ubiquitous-joint, and bilinear strain-hardening/softening ubiquitous-joint plasticity) is presented. Finally, a hypothetical coal mine roadway facing high horizontal stress is simulated. The presented model successfully shows three distinct stages of a cutter roof in a shale roof: (1) initiation of shear cracks at the rib– roof intersection, (2) extension of cracks deeper into the roof (i.e., above the roof bolt length horizon), and (3) cantilevered roof. It is demonstrated that the presented constitutive model has the potential to help future researchers in simulating various roof responses.

Jul 1, 2023

By Vincent T. Ricca

Acid mine drainage is a serious water pollution problem, for its contaminants will eventually effect the quality of the receiving streams. According to the Appalachian Regional Commission (1969)1, 10, 500 miles of streams have been polluted by mine drainage, and 70 percent of this acid pollution is accounted for by underground mines. Due to the severe damage to aquatic life, to recreational and industrial use, and to domestic water supply, more stringent mining and anti-pollution laws have been legislated and coal mine operators are required to treat the mine water discharges to meet the minimum standards. For years now, abatement and treatment methods have been extensively studied. Progress reports presented in the Fourth Symposium on Coal Mine Drainage Research, 1972 1 suggest that a thorough investigation and understanding of the basin discharge is necessary in order to cope with the mine drainage problem. The extent of mine water discharge contamination can be considered as a function of the basin streamflow and acid generation load.' A conservative treatment cost estimation these days is $0.40 per 1, 000 gallons for water with 100 ppm iron, 500 ppm acidity. These figures need not include collection and pumping costs nor the cost of dispersing of chemical waste by-products. To achieve optimal abatement and treatment of mine drainage, predictions of the quantity and quality of mine water discharges are needed. Basin discharge is a continuous process and it can be considered as a. macro-system. This system can be subdivided into micro-systems to describe the various mine discharge .types in the basin. The mining activities could produce acid water discharges from deep mines, stripmines, or associated gob piles. A total study entitled ?Resource Allocation to Optimize Mining Pollution Abatement Programs?* will consider all of these sources. However, this paper will discuss only one micro-system, the drift (deep) mine type. We will look at a single mine and its watershed. The total research project considers a multiple mining complex in an extensive stream basin.

Jan 1, 1973

By P. C. Thakur

The productivity in coal mines, measured in terns of the output per manshift depends largely on the efficiency and speed of men and materials transport between working faces and the surface. The mechanization of coal winning and material handling processes has led to a great rise in the mine productivity (1). Early applications of power in U. S. coal mines were mainly electrical. The excellent traction available with the DC motor and the ease of the distribution of the DC power have made trolley wire installations for haulage very popular. In shallow mines with very limited emissions of methane it did not constitute a major hazard but as mine depths increased and corresponding emissions of methane also increased fire and methane ignition hazards have become very serious. Conveyors have proved economic where intense mechanization of coal faces generates a large output of coal from a single face, but the fire and respirable dust hazard associated with them are no less serious. Recognizing these shortcomings, the Federal Coal Mine Health and Safety Act of 1969 laid down numerous provisions for the safe use of trolley-wire haulage and conveyors (2) which generally improve safety but in some cases complicate mining operations and have decreased productivity significantly since 1969. In course of time as coal mines become deeper and hence gassier and as the emphasis on safety increases it would be inconceivable to use trolley-wire haulage under ground as already witnessed in several other countries with deep coal mines. With rising capital investments and cost of the protection against fire and respirable dust, the use of conveyors may also have to be limited to special areas, e.g. main entries. Indeed, there are only two alternatives available, namely; (1) Degasify the coal seams prior to mining and use conventional electrical power, or (2) Develop alternate sources of power which would be safer and yet efficient and cheap.

Jan 1, 1975

By R. Schlüter

"The global mining industry is facing increasing challenges in terms of geological, technological and social aspects. Potential exploi-tation of deposits shows a tendency to increasing depth with complex ores and decreasing grades. A promising approach to deal with these constrains is by applying alternative extraction methods like (bio-)hydrometallurgy as in-situ leaching (ISL) technology. The Bergakademie Freiberg University of Mining and Technology established the “Biohydrometallurgical Center for strategic Elements” (BHMZ) to foster the interdisciplinary research along the entire biohy-drometallurgical process chain to extract indium from sulfide ores. The involved Department of Underground Mining Methods deals with the design and implementation of a pilot-scale underground testing facility for microbial in-situ stope leaching in its “Research and Educational Mine”. This paper discusses the potential of in-situ bioleaching under technological aspects. In addition, different conditioning approaches based on hydraulic and explosive methods for enhanced permeability in the formation are introduced and the gathered data will be presened. INTRODUCTION A reliable, substantial and sustainable supply of raw materials is of crucial importance for any industrialized country. This dependency applies to “strategic elements” including rare earth elements (REEs), platinum group metals (PGMs) as well as a variety of other metals like indium and germanium which are needed for high-tech industry and products such as electric and electronic devices, fibre optics and laser technology (Barakos et al., 2016; European Commission, 2010). Due to the economic growth of the BRIC-countries (Brazil, Russia, India, China), the resource policy of China as well as the volatile world mar-ket prices of different metals the availability of these critical raw materi-als and therefore the dependency of the high-tech producing countries has become increasingly important (Barakos et al, 2016). Adequate supply is often affected by the increasing depth of de-posits, lower metal concentrations and more complex ore mineralogy. In addition, mining activities are increasingly restricted by their envi-ronmental and social impact and footprints. As a consequence, con-ventional mining and processing methods are limited by high energy consumption and technical constraints."

Jan 1, 2018

By Kwadwo Osseo‑Asare, Isehaq Al‑Nafai

The hydrometallurgical processing of bastnasite is a well-known process that is used to extract rare earth metals. However, more accurate measures are required to enhance the efficiency of extracting and recycling rare earths. In this work, Pourbaix (Eh–pH) diagrams for La-, Nd-, and Pr-(F)-(CO3)-(SO4)-(Cl)-(NO3)-(C2O4)-H2O systems were theoretically derived to investigate the stability relations during the hydrometallurgical processing of bastnasite. The diagrams for RE-H2O systems show similar trends to the original ones drown by Pourbaix. The stability domains of RE carbonates were presented by RE-CO3-H2O systems with pH range of 4.5–11. In contrast, the diagrams for RE fluorides showed a large stability region of insoluble REF3 (pH ~ − 1.7–12). The decomposition behaviors of REFCO3 were studied by constructing Eh–pH diagrams for RE-F-CO3-H2O system. The stability regions of bastnasite species extend from nearly neutral to basic media (pH ~ 6.5–12). The acid treatment (using H2SO4, HCl, and HNO3) of bastnasite was investigated by constructing Eh–pH diagrams for REF- CO3-(SO4)-(Cl)-(NO3)-H2O systems. According to these systems, REFCO3 can be decomposed at pH ~ 6.5 when treated with H2SO4 and at pH ~ 1.7 when treated with HCl and HNO3 acids. On the other hand, the alkaline treatment of REFCO3 converts it to RE(OH)3 at pH ~ 11. The recovery of rare earths ions was studied with the aid of RE-C2O4-H2O systems which shows a wide stability region for RE oxalates in pH range of − 2–11. This theoretical approach explained the aqueous relations in the hydrometallurgical processing of bastnasite ore and it can improve the practical hydrometallurgical processing of such ores.

Feb 9, 2024

By John C. Stankus, Xiaoting Li

"Underground structures such as square/arch steel sets, king beam structure, etc. are widely used for the roof support in underground mines. In designing and calculating the required carrying capacities of these underground structures, how to identify the potential rock loads on the structures over long term is a challenging question for ground control engineers. Based on design practices of both surface and underground structures, the authors have designed and applied appropriate load factors in underground structural design projects to accommodate different rock types, entry/intersection dimensions, roof geologic conditions, availability of roof bolts and water, etc. Classification of load (reduction) factors for large-span underground intersections are presented for reference. Success of designed underground structures in effectively controlling roof stability over years indicates the applicability of the load factor concept for underground structural design, and its same significance as of the load factor specifications in ASCE/SEI 7-10, ANSI/AWC NDS (2015), and AASHTO LRFD Bridge Design Specifications (2012). The load factor concept will facilitate ground control engineers to appropriately utilize popular structural design software, such as RISA-3D or -2D to efficiently design and analyze underground structures.LOAD FACTORS IN STRUCTURE DESIGN APPLICATIONSIn structures, loads cause stresses, deformations, and displacements. Assessment of their effects is carried out by the methods of structural analysis with the help of load factors. Loads can be increased or decreased by load factors to meet the requirement that design strength be higher than maximum loads. For example, in designing a staircase, a dead load factor may be 1.2 times the weight of the structure, and a live load factor may be 1.6 times the maximum expected live load based on the Load and Resistance Factor Design (LRFD) method. These two “factored loads” are combined (added) to determine the “required strength” of the staircase. Some typical load (adjustment) factors used for structural design are as follows:"

Jan 1, 2019

By Stephen R. Holsinger

During the year of 1972 ASARCO's Silver Bell embarked upon a project that would test a modified grinding circuit using direct digital compute against the performance of its other five grinding lines, implementation and subsequent outcome of that project has been previously reported in a paper by Pitts, et al. The main purpose of the present paper will be to describe major problems incurred during the implementation of this control strategy on the remaining five primary grinding lines and their solutions. Also included will be a discussion of changes made in operating philosophy and methods used since that report was written. Description The Silver Bell concentrator is a 10,436 tonne/day copper sulfide plant supplied by ore from two separate open pits approximately 4 km. apart. As well as receiving ore from these two main pits, ore is received from several exten¬sions of both pits. The ore bodies are variable in rock type and the extensions have increased this variability. Grinding is carried out by six primary, single-stage, 3.20M x 3.66M Allis Chalmers grate discharge ball mills in closed circuit with four Krebs D20B cyclones (Fig. 1). Each of these grinding circuits is controlled by four independent but interactive control elements. These control elements are the fresh ore feed, the water added to the feed end of the mill, the water added to the ball mill discharge sump, and the cyclone feed pump speed. At the present time, instrumentation for measuring primary process variables consists of Merrick weightometers for fresh ore feed, orifice plates coupled with differential pressure transmitters (dp's) for incoming water measurements, back-pressure diaphragm coupled with a dp for estimating ball mill discharge sump level, a magnetic flowmeter for determining cyclone feed velocity and a nuclear density gauge for measuring cyclone feed density. All measuring instruments develop electrical signals that are measured as 2-10 V DC "inputs o the computer interface.

Jan 1, 1977

By S. Wegerer, M. Semel

The search for minerals typically starts with a reconnaissance phase. After finding a promising target area, further prospecting work will be conducted. Finally with growing confidence of having encountered an ore deposit with commercially viable concentrations of relevant minerals, an extensive exploration campaign will verify its potential. Best practice and reliable, efficient tools for mineral resource estimation of massive sulfide deposits in the deep sea have to be established yet. Therefore, a new seabed exploration system is in development. Various challenges are caused by the extreme environmental conditions in the deep sea and by the nature of massive sulfide deposits. Information of past and ongoing expeditions were gathered to form the basis of an in-depth requirement analysis. System functions and corresponding process times were derived. The experience from the existing MeBo seabed drill rigs serve as starting point for the concept study and following development. Initial MeBo system was built for maritime research purposes and now has to be converted into a new design, suitable for efficient and economic resource exploration. The new system configuration is modular structured to adapt easily to different application scenarios and challenges. To achieve an extension of the deployment depths, the overall equipment weight has to be limited through light weight construction and material. The drilling module contains a range of geotechnical coring tools to face the varying soil conditions of heterogeneous massive sulfide formations. The major challenge to overcome is the touch down sequence on uneven, 25° inclined, rough terrain in up to 4.000 m water depth. Furthermore, high precision of the final unit positioning is necessary. Landing sub-system proof of concept is validated in laboratory environment with small scale model. A novel seabed exploration system capable to land and operate safely on highly inclined slopes of mineral deposit is described. Obtaining high quality samples by wire-line coring technique is the objective.

Feb 22, 2026

By Clarence A. Johnson

The discovery of the Prudhoe Bay field temporarily reduced interest in the development of coal conversion processes, but interest is being re¬newed by the current energy crisis. According to M.A. Wright, Chairman of the Board of Humble Oil and Refining Company(l), the reserve in the Prudhoe Bay bield has been confirmed to be about 10 billion barrels. At first glance this appears to be an extremely large reserve which will eliminate supply problems for the United States for some time. This feeling of security is lost when one realizes that by 1980 the world will consume the reserves of a Prudhoe Bay or a Libya, or Venezuela in less than a year, based on the recent predictions of U.S. and world reserves made by Eastman-Dillon, Union Securities Company(2). Recent forecasts of U.S. demand and source of supply made by Kenneth E. Hill of Eastman-Dillon are shown in Figure 1. This forecast shows a decline in domestic supplies (excluding Alaska) after 1973, with the total domestic supply leveling off in 1975 at about 13 million barrels per day. Since the predicted demand increases from about 14 million barrels per day in 1970 to about 20 million barrels per day in 1980, about 35% of domestic consumption must come from imports or non-conventional sources by 1980. More imminent is the shortage of low sulfur fuel oil which has been created by the new, tough air pollution regulations that are basically legis¬lating eastern coals out of the market. As an alternate to importing large quantities of low sulfur fuel oil or importing and desulfurizing regular fuel oil, one of two domestic solutions is possible: stack gas clean-up or solids fuel pretreatment. Stack gas clean-up may be the cheapest approach for old installations, but fuel pretreatment has real advantages for new installations. Coal pretreatment at the mine could eliminate all solids fuel handling

Jan 1, 1972

By Harvey Parker

"The International Tunnelling and Underground Space Association (ITA) is a nonprofit organization that represents all aspects of the tunneling and underground space industry worldwide. Next year, the ITA will be holding its annual World Tunnel Congress (WTC) in San Francisco, CA, April 22-28, 2016. The ITA’s mission is to be the leading international organization advancing the entire industry and promoting the use of tunnels and underground space through knowledge-sharing and application of technology. This article updates a series of articles about the ITA prepared in 2007 by Harvey Parker, former president of the ITA, in anticipation of the next WTC in San Francisco.ITA accomplishes its goals through a range of activities that includes organizing conferences, workshops and meetings, working group and committee studies, training, experiments and other activities. ITA is also involved in the publication of proceedings, reports, and guideline documents as well as facilitating interaction among its membership and with sister organizations and decision makers. ITA currently includes 73 member nations and several hundred affiliate members, including 15 prime sponsors and 63 supporters. ITA’s membership is comprised of member nations as well as sponsors and affiliate members.The United States has had a prominent role in ITA since its 1974 inception, when it was formed as a result of a worldwide survey conducted in the early 1970s by the Organization for Economic Cooperation and Development (OECD). Bill Lucke, from the U.S., who was in charge of tunnels for the U.S. Federal Railroad Administration, was a member of the organizing committee that created ITA and became a vice president of ITA. Jack Lemley served as president of ITA from 1983 to 1986. Dick Robbins was active in ITA and served for many years as a member of the ITA’s Executive Council and as first vice president. Harvey Parker served as president of ITA from 2004 to 2007. Amanda"

Jan 1, 2015

By C. P. Wa1ters

This paper is written primarily from the standpoint of the miner and consumer of Missouri fireclays in refractory products, principally firebrick used in the linings of blast furnaces, hot metal transfer cars, the recuperators of glass melting tanks, and other allied uses involving contact with liquid metals and reactive slags. For these uses the manufacturing plant requires forecast of certain physical characteristics, as well as chemical characteristics, of the raw clays as a determination of practicability of mining, treatment such as pre -firing or calcining, and final usage area. These methods and results may leave something to be desired from an academic view, but are used my operation as an on-running guide to seeking and mining raw material. The high quality fireclays of Missouri are generally differentiated by the user as the softer, somewhat plastic, "bond" clays and the so-called flint clays suitable for a fired or unfired aggregate portion of a brick composition. The semi-plastic "bond" clays are mined in a producing area of northeast Missouri including Montgomery, Audrain, Callaway, Monroe, and Lincoln counties. In this geographic area the clays are the members of the cheltenham formation and occur in rather large lenses in which the usable members may approach 15 meters in thickness and an area of 6o to 8o acres. Overburden is dependent on the surface topography and, in our operations, varies from 8 meters to 25 meters. It can be up to 36 meters in the prairie uplands, but this is rarely strip mined. There was former mining by shaft and drift methods in which the overlying coal was also worked. These clays are primarily used as a binding material for other clay aggregates and is characterized by its lower refractoriness-cone 3o (165o c) to cone 321/2 (172o c), in terms of pyrometric cone equivalent, and an alumina - Al2o3 - content of plus or minus 31%. Physically, these clays are readily slaked by water to a fine grain size and exhibit a degree of

Jan 1, 1977

By Giorgio Höfer-Öllinger, Peter Pointner, Manfred Stadlober

"SUMMARY Investigations from tunnel face are part of risk mitigation measures during the excavation works. With the tunnel equipment, percussion drillings of up to 30-40m can be achieved. Core drillings are state of art method for investigation exceeding 50m. At Koralm base tunnel, up to 270m deep percussion drillings were performed with drilling rigs and accompanied by an intensive investigation program. These investigations consisted of monitoring during the drilling, field tests (with packer, using the preventer, borehole imaging) and in laboratory. Percussion drillings are cheaper and save time of interruption of the excavation progress. INTRODUCTION As part of a proper risk management, horizontal advance drillings during excavation of underground works can be seen as state of art and meet wide acceptance. Core drillings, deep and shallow percussion drillings can be differed. The selection of the type of drilling, meanwhile, causes intensive discussions. On the one hand, only a core drilling allows a direct investigation of the rock mass expected during later excavation works. On the other hand core drillings are expensive in both cost and time – if there is no excavation progress during the investigation measures – in construction time. Percussion drillings can be performed as rapid investigation measure with the excavation equipment (“Jumbo”) allowing two dimensional image of the ground around the cross section. There is some limitation concerning a reasonable depth of approximately 30m and a borehole diameter of 76mm. The applications of preventer, packer or borehole imaging are hardly applicable. By use of a drilling rig depths of percussion drillings of several hundred meters can be achieved relative easily and there is less limitation of the borehole diameter. Installation of a preventer is possible, as well as packer tests and borehole measurements (imaging, gyroscope, borehole geophysics). The gap of information between core and percussion drilling cannot be closed completely, but it can be reduced substantially and sufficiently by combination of an intensive program of measurements and analysis accompanying the investigation works."

Jan 1, 2016