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By Mark Leggett, Kevin Roberts

The need to modernise and increase the safety provision of older road tunnels raises challenges in maintaining the operation of the tunnel during such improvement works. The Mersey Kingsway twin road tunnels located in Liverpool UK, constructed in the late 1960s, have had three new cross passages constructed to allow emergency evacuation from one tunnel to the other tunnel and provide safer access for emergency services. The 3200m long road tunnels are lined with an unusual reinforced concrete steel-faced segmental lining with a paint finish. Construction of the cross passages occurred during night possessions with the tunnels returned to normal operation during the daytime. Constructed through water bearing sandstone and lined with precast concrete segments, the passages required advance ground treatment and support works. This paper presents the historical background to the Mersey Tunnels and describes the procurement strategy, design and construction approach adopted for these important safety improvements.

Jan 1, 2003

By Jack W. Murphy, Kent J. McGrew, Rudolph H. Jacobson

Introduction Maximization of profit consistent with environmental protection is the principal goal of new applications development for any conventional or in-situ mining technique. Efficient evaluation of all the parameters that contribute to mining costs and production hinges on proper design and evaluation of testing programs and data. The program discussed herein utilizes several field and laboratory procedures to estimate ore deposit characteristics and optimize lixiviant compositions. The ore characteristics and lixiviant compositions are then used in a long path leaching test (stream tube test). The stream tube test data are analyzed by mathematical models with computer assistance to predict such well-field rate parameters as target metal production, lixiviant consumption, and restoration. When these predicted rates are combined with market values for target metals, capital expenditures, prices of lixiviant chemicals, and other economic variables such as labor costs, power rates, licensing fees, and others, an assessment of the relative feasibility of various proposed mining plans is possible. The flowsheet in Figure 1 illustrates this process.

Jan 1, 1984

By Anthony G. Fonseca

About 45% to 50% of the coal mined in the United States passes through coal preparation plants. East of the Mississippi River, this number increases to about 75% to 80%. Although the cost for coal preparation is worthwhile to some, the coal industry faces the challenges of continuing downward pressure on the price of coal and the impact of new environmental regulations. Coal preparation is an effective process that achieves 75% to 80% ash reduction, 15% to 80% trace element reduction and 85% to 90% Btu recovery. It is less effective for pyrite reduction (35% to 70%) and on-line operating time (40% to 60%). It also suffers from obsolete control systems. In coal preparation, raw coal is modified to a more preferred form to enable its use. The methods used to achieve this modification must be cost-effective and appropriate to the raw coal, the scale of production and the end-user requirements.

Jan 1, 1995

By Alex Harrison, Steve Kasper

Various countries around the world have testing and manufacturing standards in place for steel cord belting. These standards are very comprehensive in what they allow the end user to specify, however, their practical significance in terms of belt life is more difficult to quantify. Such testing standards will be briefly reviewed in this paper in relation to the implication for end user expectancy. Since there is no US standard of manufacture, the end user is left with writing their own specifications. In addition, such standards do not address the effect on belt life of manufacturing faults, such as cord plane buckles, or lateral cord movement. Some new technology used to test steel cord belting will be described as an aid to both manufacturer and end user. Specific end user related issues addressed on this paper are: Tracking and belt quality Cord plane irregularities and performance Cord size and belt life Cord fatigue and testing

Jan 1, 1993

By Lawrence F. Rooney

The wide distribution of limestone and dolomite and the decentralization of the depedent industries give the State Geological Survey a major role in the, development of these mineral resources. The amount of geological information necessary for efficient exploration is so large that few companies can afford to do the necessary basic field work or store the data. The state surveys fill these responsibilities and thus might be said to serve as the geological research departments of the limestone and dolomite industry. At the Indiana Geological Survey, the data of most value to limestone producers are in the form of unpublished measured sections, well records, cores, chemical analyses, directories, and geologic maps. Much of this information is published in summary form. The Survey also assists individual members of industry in exploration and evaluation of mineral deposits. In addition, a progressive State Survey provides the geological infor¬mation necessary for the development of new resources which do not appear to justify industry's own preliminary efforts.

Jan 1, 1966

By J. C. Yingling, R. J. Sweigard, S. T. Mickleborough

The geostatistical technique of conditional simulation is applied to measure the uncertainty inherent in the factor-of-safety (FS) predictions for soil slopes in which there is an incomplete knowledge of the spatial distribution of soil properties. A case study that considers a natural clay slope in Canada is presented. The sequential-indicator simulation technique was used as a means of generating a series of spatial maps of the soil properties at the site. These maps approximate random draws from the conditional probability density function that characterizes existing uncertainty in the spatial distribution. FS determinations were made for each simulated map using the simplified-Janbu approach. In using this approach, computations are performed using a new computer program that can operate on irregular spatial profiles of soil properties specified on a discrete grid. A unique capability of this approach is the ability to generate the FS distribution conditional to the type, position and value of existing site-characterization measurements. This capability should reduce uncertainty in FS predictions.

Jan 1, 1996

By Judith M. Ballantyne

Carlin-type. disseminated, sediment-hosted gold deposits can be better described as hydrocarbon-associated gold deposits. A new genetic model for these deposits involves the intrusion of one or more small bodies of magma into a shallow hydrocarbon reservoir or ma of hydrocarbonenriched rocks, imposing a convecting geothermal system on the local groundwater. Pyrite, commonly associated with the organic material, provides a substrate for deposition of gold and other trace elements in an environment rich in dissolved sulfide. Both diagenetic and hydrothermal pyrite may act as gold depositional sites. Thermal cracking of hydrocarbons, catalyzed by illite, subsequently generates an oxidizing environment by depleting hydrogen. As oxidation increases, arsenic sulfide minerals and barite m stabiied at first. Increasing hydrogen depletion converts sulfide to sulfate, generating acid oxidizing conditions which: alter pyrite to hematite; continue the deposition of sulfates; and ultimately develop late stage acid-sulfate assemblages containing minerals such as kaolinite. alunite. and jarosite. Gold released from the oxidizing pyrite is redeposited as free gold, and pehaps remobilized.

Jan 1, 1988

By Carl P. Venzke

Mining lignite in the Gulf Coast often requires some interaction with shallow ground water system. Suggestions for determining ground water data and analysis requirements for regulatory compliance are given. Simple methods for estimating mine inflow seepage, ground water level declines, and changes in ground water chemistry, which may result from mining, are discussed. The mining of lignite often results in interaction with shallow ground water systems. An evaluation of the interaction is required as input to mine permitting and engineering. Your evaluation will proceed more smoothly and produce more meaningful results with some planning prior to performing your evaluation. The following are tips to consider in planning and carrying out a successful study.

Jan 1, 1982

By W. Kemp Wait

Electronic ore sorting has been in use for over 15 years at many mining operations worldwide. Photometric ore sorting, which operates on the basis of measuring light reflectance levels of a rock surface, is in use at various locations on ores such as limestone, magnesite, gold, talc, spodumene, tungsten and coal. Radiometric sorters have been employed on uranium deposits in the western U.S.A. as well as at certain South African go1 d mines where preconcentrating gold is achieved using uranium association as a detector. A new ore sorter, employing two sensing parameters has been developed. Utilizing both photometric and conductivity sensing modes, this system has application to many gold ore types of North America. The first production machine has been installed at a gold mine near Beardmore, Ontario for the purpose of preconcentrating ore both from waste dumps from past production as well as within the ongoing mining operation.

Jan 1, 1987

By John A. Herbst, Per-Olaf Samskog, Jan Bjorkman, Yi Chang Lo

The study described here is concerned with the development of a model for the simulation and optimization of a rod milllpebble mill circuit. A series of laboratory tests was conducted to investigate the effect of critical operating variables. The pebble mill model structure used was a population balance type which accounta for impact breakage and fines production from pebble wear. Model parameterization and verification were performed using data obtained in batch tests and in a plant test campaign. The model developed was found to provide accurate predictions of plant-scale grinding. The prediction errors are less than 21 for the product size and 31 for the mill power required to achieve that product with a mill volume scale-up of 14,000 to 1. These results indicate that accurate extrapolations from laboratory batch data to plant scale performance are poaaible using the population balance model and scale-up prediction procedures for pebble mill circuits as well as ball mills. Preliminary indications are that the new model developed here will provide vital input for pebble mill optimization and process control as well as pebble mill design.

Jan 1, 1990

By John Jonkman

During the decade of the eighties, the mining industry was able to take advantage of numerous advancements in computing technology. The development of the desktop workstation and the tremendous increase in power of minicomputers have cause many of the technical computing applications to be taken out of the "glass house", or central computing facility, and distributed to where the work is actually performed. This trend, combined with the significant price/performance improvement being experienced, has resulted in computers becoming more readily available at a reasonable cost for research and development activities, thus increasing the amount of new development taking place. The papers in this session discuss research and development work which has resulted in advancements in mining technology applications in the following areas: - Technical Parameterization - Linear Programming - Dynamic Programming - Computer Aided Design

Jan 1, 1989

By J. J. Davis, C. A. J. Fletcher, M. Li, T. Jancar

This paper summarises the experimental approach to spiral modelling at the Julius Kruttschnitt Mineral Research Centre, University of Queensland, involving the use of plastic density tracers to determine partitioning performance on three models of coal spiral. This work has led to phenomenological models of the three spiral profiles most widely used in the Australian coal industry. The results from a parallel computational fluid dynamics approach to spiral modelling currently underway at the University of New South Wales are also presented. The computational simulation has been successfully applied to generic spiral geometries and is capable of predicting the fluid phase three dimensional flow fields and corresponding free surface profiles for moderate Reynolds' number and Froude numbers. Simulation predictions are compared with experimental results from a Mineral Deposits LD9 coal spiral.

Jan 1, 1995

By James D. Reilly

The time-worn adage "an ounce of prevention is worth a pound of cure" was never more applicable than when used in reference to coal mine safety. Many individuals have dedicated many hours to developing effective accident prevention programs, and much has been accomplished. Each production escalation, however, creates new hazards and safety problems which need special study and research. It is a never ending cyle. To study the progress of coal-mine safety is to raise memories of many individuals who have been dedicated to removing the hazards that have developed with increased productivity and deeper penetration into the earth for coal. Some vivid examples of this dedication are the works of the men who pioneered the use of the safety lamp and the use of rock dust in mining.

Jan 1, 1968

By Ronald L. Haxby

This report presents a refractive seismic technique for evaluating the strength of rock within an open pit bench. A concept of correlating rock strength and seismic velocity is discussed and a method of predicting the degree of fragmentation of a pit bench is introduced, Figure 1 shows the area of interests [ ] Most of the work was performed while completing graduate studies at the University of Arizona.

Jan 1, 1967

By Kevin Bell

The TRAC™ Program was developed to provide our clients with a mechanism that allows them to better manage site remedia­tion and closure costs. This program provides a fixed-price contract for site remediation and case closure and is well suited for large pro­jects with multiple PRPs, such as Superfund sites. Because Kvaerner is a large engineering/construction firm and not a consult­ing firm, we can offer this type of contracting mechanism that envi­ronmental consulting firms are hesitant or unable to provide. With TRAC™, Kvaerner assumes financial and technical responsibilities for carrying a site through the closure process for a fixed price. Liabilities carried on our client's balance sheet for site closure can be removed when they sign up forTRAC™. In many instances, a profit can be realized as the liability on the balance sheet may exceed our TRAC™ fixed-price cost to close the site. Bonds and other sureties securing the site can be released and set­tlement with other involved parties can be quickly reached. For a project to be considered for this program, it typically meets the following criteria: 1) The project site should be physically separated from other contaminated sites 2) A reasonable quantity of site investigation data must be avail­able including site-usage history with or without a projected fea­sibility study(ies) and/or remediation design 3) Access to perform all necessary work must be available. After a review of all site data, K vaerner develops a "risk menu" to manage financial risks. In this "menu", each compo­nent of the project is assigned a level of probability that the costs will occur. Then the base cost of each activity is "weighted" by multiplying the potential cost growth by the probability. This analysis assures that the financial risks are appropriately defined, weighted, and mitigated and a realistic fixed price is developed. Upon acceptance of our proposal and conclusion of contract negotiations, Kvaerner takes over future responsibility for clos­ing your site. This allows the client to: 4) Release reserves obligated on financial statements for the site (and potentially realize a profit if the TRAC™ fixed-price cost is less than our client's booked obligation) 5) Finalize cost settlement with other responsible parties, insur­ers, etc. 6) Redirect resources involved in the environmental manage­ment of the site 7) Cap legal and administrative costs In addition to performing the site cleanup and closure work, at our client's request we are able to: 8) conclude lease obligations for property 9) dispose of equipment and buildings

Jan 1, 1998

By B. K. Mishra, B. Das, L. Panda, D. S. Rao

"The dissolution behavior of lateritic nickel ore containing 1.2% Ni, 40.6% Fe, 9.5% SiO2 and 9.59% MgO by sulfuric acid was investigated. The ore was characterized adequately by different techniques such as chemical analysis, scanning electron microscope (SEM), X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), thermal analysis and Fourier transform infrared (FTIR) spectroscopic measurements. The characterization results did not reveal any distinct mineral phase for nickel; it was associated with mineral phases like goethite, hematite, chromite and serpentine in various proportions. The beneficiation studies by hydrocyclone, magnetic separation and flotation did not enrich the nickel value. Reduction roasting followed by magnetic separation indicated only 2%Ni with 28.9% yield. Consequently, the recovery of nickel values from the lateritic ore by acid leaching under different conditions was studied. The kinetics of leaching obey the first order rate equations. The recovery of nickel was found to be influenced by temperature. It was observed that at an acid concentration of 2M, leaching temperature 363 K, time 240 min and solid-to-liquid ratio of 1:10, it is possible to leach out more than 95% Ni.IntroductionThe demand for nickel is ever increasing. Nickel is used to impart specific properties to steel, titanium and aluminium, and also is used in petrochemicals, catalysts, batteries, etc. It has been estimated that nickel oxide ores account for about 70% of the world nickel reserves. However, most nickel is sourced from sulfide ores. Nickel is extracted from sulfide ore by size reduction, followed by flotation to obtain a nickel-rich concentrate. The concentrate is then pyrometallurgically processed by smelting to produce a nickel-rich matte after discarding an iron-rich slag. Due to the increasing demand for nickel in stainless steel and other alloys, nickel is also extracted from many secondary sources. The recovery of nickel from oxide ores is now gaining momentum, and more exploitation of this ore is being attempted by advanced as well as environmentally feasible, cost-effective techniques. Dalvi et al. (2004) has reported that, due to the increase in demand, the world nickel production from laterites is expected to increase every year from the current level of production. In recent years, investigations of the use of low-grade ores, spent catalysts, clays, etc., have intensified to meet the market demand and also due to a shortage of high-grade nickel bearing ores (Al-Mansi and Abdel, 2002; Baba et al., 2009; Ismail et al., 2011)."

Jan 1, 2015

By R. Gong, R. Bhaskar

[Full-scale laboratory experiments were performed to evaluate the effect of ventilation and water spray pressure on the potential dust capture efficiency of a ventilation system comprised of blowing ventilation and an underboon scrubber. The tests were performed for a 1.52-m (5-ft) roof height and 2.36 m-3/s (5000 cfm) blowing ventilation volume, and a 2.44-m (8-ft) roof height and 4.72 m3/s (10.000 cfm) blowing ventilation volume at three face positions of the miner. The scrubber suction rate was varied for the tests to study the effect of scrubber flow rate on capture efficiency. The airflow patterns and scrubber efficiency were determined by performing tracer gas tests. Tracer gas was released through a manifold placed in front of the rotating miner drum. The gas was sampled in a grid fashion using a real-time multi-point gas sampling system. The capture efficiency of the scrubber was evaluated based an the peak gas concentration of the gas laden air drawn through the scrubber and the amount of gas passing, through the scrubber as a fraction of the gas released at the face. The data were analyzed to yield scrubber peak concentrations, potential exposures at various operator locations and the gas removal percentage (GRP). The underboom scrubber appears to work best in the end sump position, relative to the start sump and start slab positions. The capture efficiency scrubber was higher for 2.44-m (8-ft) roof heights compared to 1.52-m (5-ft) roof heights. The data also showed that the scrubber air discharged behind the mining machine may be drawn into the face area by the action of the blowing ventilation system, resulting in recirculation.]

Jan 1, 1994

By Wenhua Wan, Jan M. Mutmansky

Many concerns have been expressed worldwide regarding the use of diesel equipment in underground mines due to the potential health risks associated with diesel particulate matter (DPM). In assessing the risk to the health of miners and designing control strategies for DPM, it is important to know the concentration of DPM in the working areas of a mine. In some mines, significant stratification occurs due to the characteristics of the diesel exhaust, affecting exposure and the ability to measure DPM concentrations accurately. This study outlines some of the concentration profile data obtained during sampling at three mines where diesels were employed. Mine #1 (a gold mine) employed large openings in which a diesel-powered roof bolter was used. Mines #2 and #3 are both room-and-pillar operations with varying conditions. Mine #2 is an experimental mine where two stationary diesels were utilized for sampling purposes, while Mine #3 is a traditional evaporite operation using two mobile diesel vehicles for section haulage. These field studies indicated that some level of stratification occurred in all the mines, but the stratification was not as pronounced in the case of Mine #2 due to the complex pattern of exhaust emissions generated by the vehicles. The stratification seemed to depend on the distance from the vehicle, the mine air velocity, whether the vehicles were moving or stationary, and whether the exhaust was diluted by equipment design features. The concentration of DPM was generally higher at samplers located near the roof and lower at samplers located near the floor. However, this was not found in all cases. This paper provides conclusions on how knowledge of stratification patterns can be utilized in sampling and control of DPM in mine atmospheres.

Jan 1, 1997

By G. P. Hand

Graphite usage in the United States during 1994 was fairly strong. The hearty showing of the domestic economy, along with sound performances from the major industries that use graphite, helped make 1994 a solid year for the graphite industry. Supply Virtually all natural graphite is imported into the United States, as there is no domestic production. The primary producers are Brazil, Canada, China, Madagascar, Mexico, Mozambique, Sri Lanka and Zimbabwe. Mozambique is a new producer. It is now supplying a high-carbon, large-crystallite flake in large quantities. Sri Lanka continues to experience problems with one of its two mines, closing operations in December 1994. The synthetic graphite used domestically was produced primarily in the United States as a byproduct of electrode production. Synthetic graphite was also imported from Switzerland for specialized applications. The purified graphites/carbons, such as Desulco and ThermoPURE materials, were also produced domestically. There was a sufficient supply of all types of graphite to meet domestic demand.

Jan 1, 1995

By M. Cambridge

The extractive industries are currently, and will continue to be, major contributors to the world economy, particularly in the developing world where economic growth is dependent upon a sound supply of primary materials. However, tailings dam and other mine failures have been very much a feature of recent anti-mining publicity, particularly in Europe, and thus instrumental in inhibiting new mine developments. Although, superficially, the record of dangerous incidents might support the anti-mining position, closer inspection suggests otherwise. This paper reviews the failures which have occurred over the last 50 years and demonstrates that, though poor practice is an ongoing problem for the industry, the record is one of improvement in both design and practice. Examples are provided of significant events which have led to dramatic advances in design and operation. The paper assesses the improvements made in technology and practice, and concludes that historic events must continue to form the underlying basis for design and operation of future mining projects.

Jan 1, 2005