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By A. S. Atkins

The interest in the use of micro- organisms in the leaching of sulphide minerals has been traditionally exploited as a scavenger process for the recovery of valuable metal by- products from waste ore dumps. Environmental concern on sulphur emission from conventional pyrometallurgical plants together with the cost of stack cleaning systems to comply with legislative control also indicate baccerial leaching to offer a low cost treatment for the processing of sulphide minerals. The paper describes the effect and limits of relatively coarse particles on the complete leaching of pyrite and its importance to the practical application in dump leaching operations of sulphide minerals. It has also been demonstrated that static leaching techniques have encouraging economic potential for process plant operations compared with agitated leaching systems.

Jan 1, 1984

By Steven E. Paulson

In situ mining is emerging as a potential alternative to conventional surf ace and underground mining techniques. A major factor in determining recoveries by in situ mining is the proportion of ore minerals that can be contacted and solubilized by the leach solutions. To provide basic information on the processes occurring during in situ leaching, particularly at the microscopic scale, the Bureau of Mines has developed a geologic characterization research program. This includes laboratory experiments using leaching apparatus that can accommodate whole core samples. Whole core experiments result in higher leach solution-ore mineral contact ratios than packed column experiments, and also allow for the assessment of permeability changes taking place as the result of mineral dissolution, precipitation, and clay swelling within the flow channels in the rock. A nonreactive, reusable reaction cell has been designed and tested. The leaching apparatus can be used for constant-pressure or constant-flow experiments and allows for the control of flow rate, pressure, and temperature during the experiments, thus permitting studies on a wide variety of ore samples. Details of the experimental apparatus and design are presented, as well as preliminary results from the first series of experiments on an oxide copper ore from the Casa Grande, AZ, area.

Jan 1, 1987

By Michael Karmis

"In December 2011, the U.S. Attorney’s Office for the Southern District of West Virginia, the U.S. Department of Justice, Alpha Natural Resources (ANR) and Alpha Appalachia Holdings entered into a nonprosecution agreement related to the explosion at the Upper Big Branch Mine (UBB) that killed 29 miners. This coal operation was owned by Performance Coal Co., an affiliate of Massey Energy Co., which was acquired by ANR in June 2011, more than a year after the UBB explosion. Pursuant to the agreement, ANR agreed to:• Establish a trust within 120 days.• Pay a total of US$48 million into the trust to be used solely to fund and administer research and development (R&D) projects to improve mine health and safety.• Administer the trust by three highly qualified individuals with academic and/or professional backgrounds in mine health and safety.In April 2012, the Alpha Foundation for the Improvement of Mine Safety and Health was created. The three directors - Michael Karmis, president; David Wegman, vice presidenttreasurer, and Keith Heasley, vice presidentsecretary - approved a plan to expend both the interest and principal of the trust, aiming at an 8-10 year research horizon. The foundation also appointed David Belden, an experienced manager of nonprofits and professional associations, as the first executive director of the foundation. The IRS approved the foundation’s tax-exempt application, as described in Section 501c(3) of the Internal Revenue Code, on Dec. 18, 2012. The board established guiding principles of the foundation, which are as follows:• Mission: to improve mine health and safety through funding R&D projects to qualified academic institutions and other not-for-profit organizations.• Vision: to enable miners in the future to be free of work related injury or disease by the implementation of the results of the projects funded by the foundation and undertaken by the best researchers from any discipline that can contribute. The foundation is now approaching its third year and regularly posts updates, including semi-annual reports, to its website (www.http.alpha-foundation.org/), which serves as the main medium for communication with the broader stakeholder community"

Jan 1, 2014

By Steve Kral

Reducing the cost per ton and increasing productivity are key factors in a mine’s profitability. Mining companies can do little about commodity prices. So to keep a mine operating at a profit, management must reduce costs and improve worker and equipment productivity in every facet of a mining operation. From mining to crushing to processing, mine management is constantly seeking new methods and technologies to improve the way it mines minerals. And it is willing to borrow techniques used by other operators.

Jan 1, 2002

By Yuting Xue, Mark Van Dyke, Zoheir Khademian

Borehole scoping has been widely used in the U.S. underground coal mines as a method for geologic mapping and stability analysis because it is very useful for identifying rock types, voids, fractures, and formation boundaries through the direct observation of the borehole wall. An image stitching technique was proposed to generate panoramic borehole images from side-view borescopes in a previous study. However, the generation of panoramic borehole images can be affected by the borehole condition because the image stitching process highly depends on the key point detection and matching. The presence of dust and water could have a significant influence on the detection of key points. In this study, the influence of borehole conditions on panoramic borehole images was studied from the success of image stitching and the visibility of geologic features and lithology changes. Borehole videos recorded at different times, when the same borehole was freshly drilled, freshly washed with water and 12 days after washing, were processed with the proposed technique. The comparison of the stitched images shows that the presence of dust has minimal influence on the image stitching process but shows significant negative effects on the visualization of geologic feature and lithology change. In addition, the presence of water can significantly hinder the image stitching process, which in turn helps in identifying lithology change. Borehole scoping aids in identifying and mitigating hazardous conditions in underground mines, and this study provides preliminary inputs into identifying optimum borehole conditions for geologic mapping with panoramic borehole images.

Feb 1, 2025

By W. J. Kennedy, John D. Gardner

Introduction During the past 10 years, energy costs in mining have risen from about 4% to as much as 25% of total production cost. When combined with declining ore grades, these costs exert inordinate stress on mine productivity. Industrial engineering techniques have traditionally been aimed at improving manufacturing facilities productivity, but they have been applied to mining as pressure for productivity improvement has increased. These techniques can perform four useful functions for mining operations by improving methods, equipment selection procedures, energy use through scheduling, and managing energy costs rather than being managed by them. This article discusses some of the standard techniques for productivity improvement, and how they can be adapted to perform these four functions. Pre-Production The best time to seek high productivity is when a mine is being planned. During pre-production, when most options are still open, an optimum mine design is achievable. At this time, major equipment selections are made, the layout, material handling systems, and processes are designed, and critical energy source decisions are made. By including explicit energy cost projections, decisions can be made that will save significant amounts of money per ton of ore over the life of the mine. Attention can also be given to often overlooked details such as lighting. Some of the same tools used in new mine planning are applicable to productivity improvements at an existing plant. These tools are the charting and modeling methods that have been developed by industrial engineers over the past 75 years. Energy Consumption Before any analysis of energy consumption can be performed, preliminary work is necessary to find the kind of energy used, how much it costs the plant, and when electrical peaks occur. Past bills should be examined to determine the monthly consumption rate and the cost of each energy type. These data should be adjusted to remove effects caused by production fluctuations or weather. Knowing when electrical peak demands occur is necessary because these determine either the electrical capacity needed or the amount that must be bought. At $500-$800 per kW for construction or $5-$15 per kW per month for purchase, they represent a significant cost. By the time these data are collected, planners should be aware of the importance of energy in the total cost of mine operation, and should have the most crucial time data for electrical peak demand. Flow Process Chart Reducing costs can be accomplished by a thorough look at mine systems and how altering one system causes changes in others. By developing and exercising models of production processes outward to the transportation of the final product, otherwise obscured weaknesses may become apparent. There are tools available for analyzing the mine and its associated systems; one of the most useful is the flow process chart. The flow process chart gives a system analysis of a production procedure by classifying all actions into one of five types: operations, inspections, transportation, delays without paperwork, and delays with paperwork. Operation: In an operation, the nature of something is changed. Examples are blasting, washing coal, and processing matter. Denoted by 0. Inspection: Examining an object for identification or to measure some attribute. Examples are determining whether a drill hole is deep enough, deciding how far to cut under an unsupported roof when operating a continuous miner, or checking the lubricant level on a truck. Denoted bye. Transportation: Moving an object from one place to another. Examples are transporting overburden, moving coal on a conveyor belt, and pumping water. Denoted by =>. Delay without paperwork: A delay that is an inherent part of the system. Examples include idle time of a continuous miner while waiting for shuttle cars or for roof bolting, crushed ore in a storage area waiting for grinding and flotation, and people from one craft waiting for another craft to finish. Denoted by D. Delay with paperwork: A delay that can be terminated only by some written authorization. Examples are coal that cannot be removed until authorized by a bill of sale and transportation orders, personnel records, maintenance, or spare parts. Denoted by V. In practice, the flow process chart is completed after data collection and a detailed examination of the process. Data collection is needed to answer questions on distance, quantity, and time for each of the operations. As the analysis is being performed, each step of the process is subjected to these questions: • Why is the step necessary? • What is being moved? • When does the step take place, and why?

Jan 11, 1983

By William Gleason

"In 2008, the world quietly hit a milestone that did not receive much fanfare or publicity, but it hit one that marked a turning point in the history of mankind and the way the planet is and will be inhabited in the future. It was in 2008 that, for the first time, more than half of the world’s population, an estimated 3.3 billion people, resided in urban areas. The world’s population had moved from being a majority of agricultural and rural society to an urban society. Andrew Whalley, deputy chairman for Grimshaw Architects, said this change in where and how people live will continue to increase urban populations and, by 2050, it is estimated that more than 6.4 billion people will live in urban areas. To meet these needs, Whalley, speaking during the keynote session of the 2105 Cutting Edge conference in Denver, CO, said future cities will have to be reimagined and redesigned to be more efficient. A large part of that design will be in the infrastructure of those cities.At the Fourth Annual Cutting Edge Conference, Sept. 21-23, much of the discussion was around how the tunneling and underground construction industries improve cities in a number of ways, including societal, environmental and in overall efficiency. There was talk, not just about the improvements that society enjoys at the completion of such projects, but also about the challenges faced by the owner and contractor in the construction of such projects.The conference, titled Urban Tunneling, brought together some of the top minds in the industry to not only discuss the issues faced today, but also those that will shape the industry in the future.For his part, Whalley spoke about a number of projects around the world and how they have impacted society in ways beyond simply providing a better means for transportation of people or water. Notably, he spoke about the Crossrails project in London.London is a city of 8.6 million people and a history that dates back nearly 2,000 years. It is a great example of the challenges the industry faces in bringing modern efficiencies to an established city.Running more than 100 km (62 miles) with more than 42 km (26 miles) of tunnels passing through 40 stations, including 10 new stations, the project is the largest in Europe and will transform the way people move about the city."

Jan 1, 2015

By B. Briggs

Over the past 15 years, the tunneling industry has pushed towards a higher degree of mechanization in nearly every phase of construction. The overall objective of the mechanization was to increase production and the level of safety in tunnel operations. However, the overall complexity of some systems have been a hindrance to a seamless transition to the newer technologies as increased maintenance requirements and re-training of skilled workers has altered the benefit curve for some innovations.

Jan 1, 2010

The General Purpose Simulation System (GPSS) is a computer simulation language that has been used for simulations of open pit haulage operations since the 60's. It is easy to learn, simple to use, and has a block-diagram structure that is amenable to load-haul systems. However, due to its lack of flexibility, there are situations where another language should be chosen. This paper reviews the characteristics and capabilities of both GPSS and FORTFAN with regard to open pit shovel and truck simulation. The relative advantages and disadvantages are highlighted and a case study presented along with comparative results from two computer models (one written in GPSS and the other written in FORTRAN).

Jan 1, 1986

In September 2003, a test was conducted to see if a115-mm- (4.5-in.-) diam Mocap Vari-Stem blasthole plug could improve the pattern of explosives using different top stemming material. The test took place at the J.S. Faulkroad and Sonsstone quarry in McCalisterville, PA. The test consisted of a production stone blast. Half of the holes were stemmed with standard crushed stone. Two-thirds of the remaining half were stemmed with Vari-Stem plugs and crushed stone. And the remaining one-third of the second 50 percent was stemmed with Vari-Stem plugs and only drill cuttings.

Jan 1, 2004

By D. B. Buddecke

Powell Bend Mine, located in Bastrop County, Texas, is owned by the Lower Colorado River Authority (LCRA). The mine is operated under contract by the Powell Bend Mining Company (PBHC), an affiliate of Pittsburg and Midway Coal Mining Co., and produces 210,000 tons of 6500 BTU/LB lignite per year for LCRA's Fayette Power Project near La Grange, Texas. PBHC operates the surface strip mine one shift per day, five days per week with a total of nine employees; six operations/maintenance and three office/supervision. The mine's productivity in 1988 averaged 100.3 tons per manshift using an l8-cubic yard dragline to uncover the lignite. Delivered cost to LCRA, F.O.B. mine, is $6.11 per ton, which includes water control and final reclamation.

Jan 1, 1990

By H. I. Kim

The leaching of a complex matte in chlorine and chloride media was studied. The matte was prepared from manganese nodules by the reduction smelting-sulfidation route. From XRD analysis, the major phases of the matte were identified as CuFeS2, CuS2, (FeNi)9S8, (FeNi)S2, Ni9S8, Ni3S2, (CoFeNi)9S8 and Co metal. Investigated were the chlorine, hydrochloric acid, hydrochloric acid-oxygen, ferric chloride, ferric chloride-oxygen, cupric chloride and cupric chloride-oxygen systems. The results are discussed in terms of reagent concentration, retention time, leach temperature and gas sparging rate. The chlorination process resulted >99% metal extraction efficiency within a short retention time and at atmospheric temperature. However, there were no preferential extractions of Cu, Ni and Co with respect to Fe. The cupric chloride-oxygen system produced leach liquors with the lowest Fe content and with a high base-metal extraction. Sulfide sulfur was converted to mixtures of elemental sulfur and sulfate in all the studied systems.

Jan 1, 2009

By R. L. Grayson

As the total cost of labor has significantly increased over the past ten years, older underground mines have found it more difficult to compete- in a limited demand coal market. Many of the older mines were developed extensively into a reserve requiring a large number of workers to maintain and rehabilitate extensive track haulages and/or belt conveyor systems. Often, a large number of fans were required to maintain minimal airflows in areas where poor conditions and huge leakages prevail. This paper focuses upon problems which beset one such coal mine and projects undertaken to restore it to potential profitability.

Jan 1, 1986

By S. Boone, J. N. Shirlaw

INTRODUCTION Soft, near normally consolidated clays generally provide ideal conditions for tunneling using Earth Pressure Balance (EPB) shields. It is easy to turn the clay into a low permeability, viscous spoil that can be pressurized to maintain the required face pres-sure. Despite this, there are records of relatively large, and often quite variable, surface settlements over EPB driven tunnels in soft clay. To understand this variation it is necessary to identify the various factors that contribute to settlement. Tunnels in soft clay are ideal for study these effects in the field, as an unsupported void will close almost immediately, due to the low shear strength of the soil. In the short term, deformation in a soft clay will occur at constant volume, so short term surface settlements can be related to movements at tunnel level. In this paper, data will be used from EPB driven tunnels in Singapore marine clay. In all of the cases discussed the lining consisted of precast concreted segmental rings erected in the tail of the shield. The marine clay in Singapore has been studied, among others, by Tanaka et al.(2001). The clay typically has a plasticity index of 40 to 60, and the undrained shear strength (SU ) can be derived from: SU = 0.22 svo' where svo' is the current vertical effective stress. Figure 1 shows a summary of undrained strength/depth plots used for design on two sections of Singapore’s North East Line. The stability of a tunnel in clay can be assessed by comparing the stability number (N) of the tunnel with the stability number at total collapse (NTC). The stability number can be calculated from the equation: N = (?Z + q – Pt)/SU where: ? = the average unit weight of the ground above the springline of the tunnel Z = the depth to the springline of the tunnel from the ground surface q = the surcharge Pt = the support pressure within the tunnel The stability number at total collapse depends on the size, geometry and depth of the tunnel, and typically ranges between 5 and 9. Charts for assessing the number at total collapse are provided in Kimura and Mair (1981), based on the testing of model tunnels in a geotechnical centrifuge. For tunnels in the Singapore marine clay, the stability number of an unsupported tunnel would be over nine if the tunnel ois more than 8m deep. As a result, a support pressure

Jan 1, 2007

By Tom Szaraz

Part of a major sewer expansion for the City of Columbus, Ohio. The Big Walnut Outfall Augmentation Sewer?Part II (BWOAS) consists of 13,200 feet of tunnel of 12-foot tunnel passing mainly through glacial deposits with a water head of up to 2 bar. A Lovat RME167SE was used to drive this tunnel with steel fiber reinforced precast segmental liner used for support. This paper will discuss the concepts for tunnel sup-port and TBM selection, the problems encountered with the TBM sealing systems and the solutions used to repair the machine.

By Mark E. Gershon

Extensive efforts are under way to- ward applying computer techniques to mine production scheduling problems. These efforts are concentrated in four areas: optimization, computerization of traditional methods, heuristics and simulations. These areas complement each other rather than compete. Characteristics of each are discussed toward enabling the engineer to evaluate specific systems that may be encountered. Alternative approaches within each classification are described as well as the motivation for each.

Jan 1, 1985

By P. M. Godinho

The debut of the sustainable development concept in the political arena, and the publication of Our Common Future in 1987, represents the starting point of present concerns and efforts associated with the sustainability of the ecosphere and its ecological and human subsystems. The sustainable production and consumption of natural resources, in particular mineral resources, represents a central aspect of the problem. In this context, an important goal has been to develop sophisticated management systems, which consider sustainability principles, in organizations within the system of minerals and metals (SMM). The development of indicators is only part of this challenge. The extractive industries (EI) as an important stakeholder of the SMM (should) have similar priorities. If embraced, this challenge offers great opportunities, one of them being the potential for advancing the understanding of how these organizations learn and change. The identification of its main determinants offers, in theory, the possibility for their management and a faster achievement of the sustainability levels to which they (should) aspire.

Jan 1, 2007

By Erich J. Jacob

In the past 15 years the enforced improvement of the public traffic systems caused a boom in urban tunnel construction. In 1961 the City of Paris started to build the Express-Metro. Of the 47 km long double-track line crossing the city center, nearly 45 km are in operation since 1971. Still missing is here only an about 2.6 km long connecting stretch, which is under construction now. From 1963 to 1969 the 21.8 km long Victoria Line was built in London as extension of the existing network,. A little later, in the years 1965 to 1973, the City of Hamburg supplemented its subway network by the construction of a 16.8 km long line between the Boroughs of Billstedt and Stellingen. Also in 1965 the City o Munich started to build a subway system of 54 km f length. Thereof a stretch of 16.2 km could be taken into operation in 1972 shortly before the Olympic Games. These are only some of the better known projectsas examples of the activities in European cities. In nearly all cities with more than about ½ million inhabitants subsurface traffic lines were begun or supplemented. Furthermore, numerous undercuts or other subsurface structures were built. The Ij Tunnel in Amsterdam and the new Elbe Tunnel in Hamburg may be mentioned, both structures finding international attention.

Jan 1, 1976

By William R. Bond

The pressure/vacuum lysimeter is being used as an effective vadose zone monitoring device for mining heap leach facilities, tailing disposal ponds and tailing waste sites. Their use has proven reliable for baseline data collection, early warning leakage detection and analyzing geochemical variations in the vadose zone. The lysimeter structure utilizes a closed cylindrical chamber made of PVC or inert material. The soil water intake portion of the cylinder is made of a porous material of low permeability. The application of vacuum or pressure to the unit is via two access tubes from the ground surface. Available soil moisture is drawn by vacuum through porous material into the lysimeter chamber and then collected from the access tubes. Case studies show their usefulness for monitoring around a uranium tailing pond constructed in glacial till material, under heap leach pads and pregnant, barren, and overflow ponds, and investigating the movement of contaminant moisture through old tailing deposits. Relatively easy to install and sample, regulatory agencies and facility operators are accepting and negotiating for their application as a site integrity monitoring device and unsaturated zone research tool. Their use at heap leach facilities lends credibility to solution balance calculations when considering a leachate loss of 5 or 10 percent can make or break a mine's profitability.

Jan 1, 1984

By Yanan Zhang, Hongwei Deng, Feng Gao, Bo Ke

Recently, liquid carbon dioxide (L-CO2) blasting technology has attracted attention due to its good fracturing effect and safety performance, especially in coal seam permeability improvement. This paper analyzes the blasting effect of L-CO2 based on experiments and studies the fracturing mechanism from the perspective of stress wave action via theoretical analysis and peridynamic simulations. The results indicate that L-CO2 blasting achieves a good fracturing effect without forming a crush zone, and the loading rate and strength of the stress wave are key factors.

Jan 19, 2022