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By Monserrat Rebolledo, John L. Uhrie, Candice Simms

Jetti Resources has developed a catalyst which overcomes the passivation of primary sulfides, enhancing the heap leach recovery of copper from chalcopyrite. It is important to emphasize that heap leaching of copper sulfides, whether with or without the Jetti catalyst, is a biooxidative process. We have demonstrated the efficacy of Jetti’s technology in bioreactors, with a chalcopyrite-dominant porphyry ore. In the presence of Jetti’s technology, optimal bioleaching conditions significantly increase copper extraction by 2.6 times that of the baseline.

Feb 1, 2025

By George J. Karabin

Over the past few years, the use of fully grouted bolts to support the roof of underground openings has increased dramatically. While conventionally anchored bolts effectively reinforce the strata of over 80 percent of mine workings, the use of resin grouted bolts in areas of severe roof conditions has resulted in a substantial reduction in roof falls and an overall improvement in both safety and production. The Roof Control Group of Pittsburgh Technical Support Center, Mining Enforcement and Safety Administration, has conducted numerous field and laboratory investigations to isolate parameters which contribute to the effectiveness of both conventional and resin bolting systems. Specially developed strain-gamed resin bolts, compression pads and differential sag stations installed during the mining cycle have generated data reflecting the loading characteristics and resulting roof stability associated with each type of support. Additional investigations have produced optimum installation parameters of the two systems including the effectiveness of thrust/torque controls for conventional bolts and various bolt/ hole diameter combinations for fully grouted rods. Theoretical analyses, coupled with the actual field and laboratory findings and numerous installation observations have facilitated basic comparisons of the working mechanisms and failure modes of both resin and conventional systems.

Jan 1, 1976

By T. W. Newell

Small tonnage ore bodies can be developed at a profit on a short life basis. Such is the case of the Bardon Mine in. the Big Indian Mining District in San Juan County. Utah. Faced with a small initial tonnage of high grade uranium ore, the Shattuck Denn Mining Corporation Engineers developed some new ideas for sinking the shaft and planned extraction to warrant the capital risk to mine a limited reserve. The Bardon Mine is located fifty miles southeast of Moab, Utah in the south end of the Big Indian Mining -district. Shattuck Denn Company, a wholly owned subsidiary of the Shattuck Denn Mining Corporation, manages and operates the property under an operating agreement with Kerr-McGee Oil Industries, Inc. of. Oklahoma City. Oklahoma, and Anderson Development Corporation of Albuquerque, New Mexico. Based. on Kerr-McGee drilling., a tabular ore body about 350 feet long by 250 feet wide with an average thickness in excess of seven feet was indicated.- The ore body strikes easterly-westerly and dips from nine to twelve degrees to the south. Uraninite is the dominant uranium ore mineral associated with vanadium. The ore occurs in an arkosic conglomeratic sandstone with some interfingering of mudstone and shale in the Mossback member of the Chinle formation in contact with the underlying Cutler formation. The ore horizon is overlain with 40 to 60 feet of mudstone and shale. Fortunately, the back. immediately over the ore is a reasonable competent shaley sandstone which has made a fairly good. environment for roof bolting.

Jan 1, 1960

By Nick Chlumecky

INTRODUCTION Column-type supports are used to prevent roof falls in underground excavations. The first individual column supports were made from timber that was cut to fit the irregular heights of mine seams. Because the seam height of the material removed varied throughout the mine, timber posts generally could be used only once. During the I 920s, steel friction props began to appear in British and European mines, and, by the 1950s, thousands of these props were being used. However, the steel friction props were heavy, difficult to install, and difficult to recover. Furthermore, the friction props could not be preloaded, and their yielding behavior was rather erratic. In 1946, hydraulic props were introduced in En¬gland, and, within a few years, they replaced friction props throughout Europe. The first application of hy¬draulic props in the United States occurred in the 1950s, during early experiments with longwall mining. Modern technology and high-production mining procedures have combined to make the use of hydraulic props a very acceptable method of providing temporary heavy-duty support for production areas. In areas such as development headings, where only modest roof loads are expected, lighter-duty jackscrews, ratchet jacks, and light hydraulic props are used. ADVANTAGES OF HYDRAULIC SUPPORTS The acceptance of hydraulic supports has been wide¬spread during the past 25 years, proving their reliability and effectiveness in preventing roof falls. Some of the advantages provided by hydraulic supports are: 1) Individual hydraulic props can be installed within 30 sec, resulting in a minimum exposure of per¬sonnel and equipment to an unsupported roof. 2) Hydraulic props can be preloaded to more than 4.5 t (5.0 st), increasing the frictional resistance between the rock strata. Thus, the roof is kept tight, improving the behavior of the unsupported ground. 3) If gradual roof sagging or bottom heaving im¬poses an irresistible force, the hydraulic prop yields gradually and continues to support the ground. 4) The support capacities of the hydraulic props most widely used range between 10 and 20 t (11 and 22 st). Their support capacities are maintained during yielding to an irresistible force. 5) Hydraulic props can be recovered rapidly. Where no other supports are provided for the roof, as in pillar¬ing operations, the hydraulic props can be recovered by remote means. 6) The length of hydraulic props is readily adjust¬able allowing them to be reused in seams where roof height varies. 7) Studies of mining operations indicate that the use of hydraulic props increases both personnel safety and mine productivity. DESCRIPTION Figs. I and 2 illustrate typical hydraulic props used in mines in the United States. Fig. I illustrates a prop

Jan 1, 1982

By Jack D. Melin

The commercial development of the Liwell Screen is a result of a thorough search for a non-blinding and highly efficient screening device capable of handling even the most difficult-to- screen feed materials. A proprietary development of Hein, Lehmann A.G. of Duesseldorf, West Germany, the Liwell Screen utilizes a unique flexible deck motion for sizing a variety of sticky, high surface moisture feed materials including raw coal and lignite at separations ranging from 3/4-inches (19mm) down to 10 mesh (1.5 mm).

Jan 1, 1983

By Mark H. Johns

Leaching of waste material at Kennecott's Chino Mines Division at Santa Rita, New Mexico, has been accompanied by increasing difficulty in circulating leach solutions through the dumps. As a means of recognizing existing problems and considering alternative applications of the leaching concept, a leaching research program was proposed which could be applied to a specific, typical waste dump. Conclusions derived from the area could then be applied to other leaching areas at Chino. Associated with the program was an evaluation of the physical characteristics of the area using Chino's drilling and radiation logging techniques.

Jan 1, 1970

By J. Steven Whisler

Corporate managers are facing increasingly demanding challenges as they seek to ensure compliance with environmental laws. Management also must deal with new liabilities created by environmental laws. These laws provide both private groups and governmental agencies with access to the courts to seek penalties, compliance orders, cleanups, or to forestall developments that could affect ecosystems. Environmental laws and liabilities are also affecting commercial transactions, including the availability of financing. Corporate managers must develop new and innovative methods to address these challenges in order to assure both sustainable industrial growth and stewardship of the environment.

Jan 1, 1991

By Harry Asche

The last 12 months has seen the construction of the first Earth Pressure Balance (EPB) TBM excavated tunnel in New Zealand on the Project Hobson sewer storage tunnel for Watercare Services Limited, with the concurrent excavation of the second EPB tunnel on the Rosedale Outfall project for North Shore City Council. Together these tunnels involve a total length of 6km and follow an 8 year pause in TBM activity in Auckland. TBM performance on these two projects is thus of significant interest as there are four major tunneling projects totaling over NZ$8B being planned for Auckland, in similar ground conditions. Auckland?s bedrock is a weak sandstone/siltstone (East Coast Bays Formation), subject to infilled paleovalleys. The geology in the region has been significantly influenced by volcanic activity; 49 volcanoes are present within 20km of the city centre. The paper describes the design and construction challenges for the projects, including TBM performance, ?sticky spoil? management, and risks associated with basalt lava flows and two paleovalleys. Watercare?s Project Hobson also saw the successful implementation of a Geotechnical Baseline Report?one of the first uses of this type of document in Australasia. Rosedale Outfall is designed for high internal water pressures with varying hydraulic flows, with the risk of exfiltration explicitly addressed.

By M. J. Blattman

Upon completion of an underground mine design, the planning engineer is faced with a surprisingly complex problem, “What development and mining sequence should be implemented so as to maximize the return on investment?” The problem relates to the scheduling of development headings to access stope production areas in such a way that the most money is made as quickly as possible for as long as possible. The total dollar value of the stopes, the average grade, the total tonnage, nor even the profit margin do not accurately give an indication of the “proper” mining sequence on their own. This paper will outline a method being developed by the author that can create a sequence of events that maximizes the net present value (NPV) of a given development and production design using information already being generated during the design process.

Jan 1, 2003

The CERAMEC pressure filter is used for the filtration of fine materials whose cake moisture cannot be achieved with vacuum. Development work has been carried out to achieve a well-controlled cake forming and cleaning of the filter media as well as an efficient solids discharge system. Operating costs are low due to low energy input and negligible consumption of pressurized air.

Jan 1, 1999

By Om P. Garg

The purpose of this paper is: 1) To summarize the capabilities and some of the limitations of the existing mine planning software. 2) To provide some guidelines for acquiring the software. 3) To identify problems and challenges in terms of how to justify increased use of computers (particularly the 32-bit microprocessor based super micro computers), for various activities related to a mining operation No attempt has been made to review the contents of available software packages in detail. Also the scope of this paper is limited to mine planning related computer applications. Applications related to accounting, inventory control, preventive maintenance, equipment scheduling, etc. have not been covered.

Jan 1, 1983

By Anthony D. Hammond, Charles A. Kliche

A slope stability study for the Annie Creek and Foley Ridge Mines was undertaken to provide Wharf Resources, Inc. with a technical assessment of the stability of the slope for an overall pit slope angle of 60°. A rock analysis of the most critical and persistent combination of discontinuities was carried out using probabilistic methods. A detailed discontinuity mapping and assessment of the rock mass provided the orientation data used in this study. The orientation data were reduced and analyzed to identify the discontinuity sets. A statistical analysis provided information about the distribution of the data. A deterministic wedge stability analysis identified the critical combination of discontinuities; those with a low factor of safety were further studied using probabilistic kinematic and kinetic stability analyses. The results from this approach were used to obtain the reliability or probability of failure of the slopes.

Jan 1, 1988

By George H. K. Schenck

The North American-based mining engineer needs to understand the differences that exist between mechanical mining or boring machines built on this continent and those built in Europe. The differences Ere most clearly seen when machines for large-sized openings--about 15 feet high-are considered. This report will focus on the innovations of European origin. The rock-breaking tool, drag bit, or roller cone that is efficient for a particular project is related directly to the strength of the rock involved. This strength is generally stated in reference to the rock's unconfined compressivee strength in pounds per square inch (psi) although it is well recognized that a rock's shear strength is also important. Compressive strength has been adopted because it is simple to test for and provides a convenient comparison. Table 1 relates cutter type to compressive strength and indicates the general nature of the machine innovation devel¬oped in Europe.

Jan 1, 1970

By Irving Hoch

INTRODUCTION The demand for tunnelling can be related to urban population size and density; often, tunnelling occurs when a certain city size and density threshold is reached, and increases thereafter as a function of those population characteristics. Subways for rail mass transit are the most notable example, of course, but tunnels for water supply and perhaps for sewerage can also be related to size and density. As cities grow large they sometimes outgrow their local water supply and have to import water from distant places via tunnels; witness New York City, Los Angeles and San Francisco. And it has been suggested that Chicago use deep tunnels for storm water storage because tertiary treatment to meet water quality standards will require treating storm water runoff.(1) Other uses of underground space also increase with urban density, e.g., underground parking, concourses and shopping centers such as Rockefeller Center in New York City and the Place Ville-Marie in Montreal. These examples can be viewed as illustrative of the central point of urban land economics. As the number of people locating in a place increase, they bid up land values and make the more intensive use of land economic, with land defined to embrace the space both above and below the surface. Hence, we are led to think about the city, and of urban land use, in three dimensions. Now, if we accept the relation of underground space use to urban size and density, recent demographic trends seem anything but hopeful for future tunnelling demand: urban density is declining, population growth is slowing down generally, and there

Jan 1, 1974

By M. Manrique

Various pyrometallurgical methods for treating Ilmenite and Zircon concentrates are reviewed. Laboratory experiments, using a thermal plasma reactor, have been performed to evaluate: the conversion of ilmenite to TiC or TiC-Fe and the conversion of zircon to ZrC or ZrC-SiC. Results are examined and possible processing routes are identified.

Jan 1, 1996

By David Smith

Construction of a new transportation link frequently requires crossing under an existing highway or railroad. Although traffic diversions may permit a cut and cover structure to be built, ‘zero impact’ tunnel solutions are becoming increasingly popular. The vertical clearance between the new tunnel structure and the existing highway or tracks may be very low; sometimes less than two meters. This leaves little room for error since any ground loss can rapidly translate into surface settlement. Problems can be avoided by maintaining the stability of the tunnel face and by minimizing ground movement around the tunnel lining. This paper examines construction methods that have been used to construct short tunnels with shallow cover, and highlights factors to be considered for future projects.

Jan 1, 2005

By Walid M. Abdellah, Soliman Abu Elatta A. Mahmoud, Hanaa A. Abu Khoziem

The high-grade Th-U-Y zone is one of the numerous mineralized zones found in the El Garra El Hamra hydrothermally altered syenites in southwestern Egypt. It is characterized by the thorium minerals thorite and thorogummite, which are closely associated with xenotime-(Y). This zone of mineralization is localized in the eastern part of the El Garra El Hamra hydrothermally altered syenites. This zone does not relate to the first phase of syenites that appeared on the surface but is linked to the other, hidden phase of the syenitic body. Additionally, the fluids responsible for the mineralization of this zone belong to the late-stage hydrothermal event as well as the fault action due to the fact that it had continued reactivations for a long period of time. The studied mineralized zone also contains ceriopyrochlore-(Ce),(Ce,Ca,)2 (Nb,Ta)2O6 (OH), fluorite (CaF2) and barite (BaSO4), which are found in considerable amounts, whereas apatite (Ca5(PO4)3F) and chromite (FeCr2O4) are rarely found together with Fe-oxi-hydroxides (hematite and goethite) with a minor amount of jarosite (KFe33+(OH)6(SO4)2). Finally, the main constituent mineral in the zone is the pseudomorph perthite in addition to quartz, which is found as deformed crystals. A technological sample was collected from this zone and was found to assay 4.62 weight percent thorium (Th), 0.37 weight percent uranium (U) and 3.12 weight percent rare earth elements (REEs). From the chemical and mineralogical composition of the studied technological sample, the leachabilities of Th, U and REEs were investigated using sulfuric acid (H2SO4) agitation leaching and pug leaching methods. The latter was found to be preferred under the conditions of 0.54 ton H2SO4 per ton of altered syenite at 110 °C for two hours.

By Richard H. Follis

Activated carbons used for precious metal recovery from carbon-in­pulp (CIP), carbon-In-leach (CIL) and carbon-in-column (CIC) circuits often become fouled with Inorganic precipitates (i.e., CaCOa, CaS04, SI02), and adsorbed organics (I.e., petroleum distillates from lubricants, dissolution products from wood) (1,2). These contaminants occlude carbon pore structure, such that diffusion controlled adsorption and desorption (elution) of Au(CN)2-and Ag(CN)2· are lmpeded(3,4l. Thus, after only short exposure to the hydrometallurgical environment, the characteristic carbon activity is reduced(5l. By frequently regenerating circuit carbons, activity losses associated with fouling can usually be minimized. Regeneration typically Involves (not necessarily Is this order): 1) elution to remove adsorbed ionic species (e.g., until they are removed from the carbon pore structure, Au(CN)2" and Ag(CN)2-are contaminants )(6l; 2) acid washing with 3-15% (wt/wt) hydro­chloric acid, to dissolve soluble Inorganic precipitates such as CaC03; 3) neutralization and/or water rinsing to remove residual acid; 4) thermal regeneration at 350-650 °C to remove adsorbed and/or pyrolyzed organ­ics; and 5) screening to remove fine carbon particles produced by Impaction and abrasion in the various stages of the hydrometallurgical circuit (i.e., adsorption, elution, and regeneration). The overall process Is purposed to reopen the circuit carbon pore structure, and to maintain the activity and qualities of virgin (new) carbon(7,8l. While most CIP, CIL and CIC operators regenerate circuit carbons, few evaluate the effect of the process on carbon quality in a systematic way. Process control usually Involves Iterating critical regeneration parameters such as: acid concentration; time frames for acid washing and water rinsing; and temperature and residence time for thermal regeneration. Carbon quality control frequently comprises only sporadic activity tests performed on non-representative grab samples dipped from conve­niently accessed carbon storage bins. So, regenerated carbon quality may vary and (at times) be unacceptable for effective hydrometallurglcal circuit operation. To verify the efficacy of the regeneration process and assure accept­able adsorption and elution rates for Au(CN)2· and Ag(CN)2·, operators should systematically assess regenerated circuit carbon quality. This paper, then, suggests methods for effectively assessing circuit carbon quality, Including: carbon sampling procedures; standardized physical and chemical test methods; and criteria and general procedures for comparative adsorption rate (activity) testing. Also, a two tier quality control testing scheme is proposed, and techniques for presenting and interpreting test data are demonstrated.

Jan 1, 1992

By T. Braun

A greenfield open pit gold mine in Latin America suspended operations less than three years into an eight-year mine plan after a waste rock dump and heap leach facility sustained substantial damage from a deep-seated landslide. No injuries to employees were recorded because of the slow-moving failure. Due to early detection by the operations team, the owner had sufficient notice of the potential failure and successfully rinsed the heap leach facility prior to the failure event. Engineers estimated approximately 35 million cubic meters of mass movement below the waste rock and heap leach facilities. The original eight-year mine plan produced approximately 60,000 ounces of gold per year. After the failure, the owner terminated gold production, re-configured the mine site to a safe, standby condition and launched a detailed investigation into the root-cause of the failure. Approximately two years after the shutdown, legal interests filed a statement of claim and named three engineering design firms and individuals involved in the project. Several years of litigation, including discovery and deposition proceedings, followed as the legal process considered evidence spanning a 20-year timeline. Changes in project ownership and consulting firms during the development and operations phase complicated the process. In 2017, the plaintiff and last defendant settled. The author was involved as the corporate representative for one of the engineering design firms.

Mar 2, 2022

By Scott Thayer, Michael Murphy, Natalie Cope, Gabriel Esterhuizen, Anthony Iannacchione, Tim Miller, Brent Slaker

"The Subtropolis room-and-pillar mine extracts the Vanport Limestone (Allegheny Formation, Pennsylvanian System) near Petersburg, Ohio. Strata instability problems associated with excessive concentrations of lateral stress caused the mine operator to implement a change in layout design. This mining method has been identified as a stress control layout, which has been used by other underground stone mines in the past with varying degrees of success. Practical experience has shown that entry headings advance in the direction of the principal lateral stress, producing lower stress concentrations with better mining conditions. It is important to minimize stress concentrations along the mining front, so an arrow-shaped advance is recommended. This technique advances more developments (headings) in a “good” direction and reduces developments (crosscuts) in a “bad” direction. As is expected, the stress control layout enhances the potential for shear failures in crosscuts. It is, therefore, important to focus crosscut engineering interventions that either: (a) lower stress concentrations (for example, an arched roof) or (b) enhance strength of the strata containing the shears (for example, rock reinforcement). This study focuses on observing strata conditions on a regular basis and monitoring the response of this strata to changing geologic and mining conditions through 3D Dynamic LiDAR scans.INTRODUCTIONProject AimsThe Subtropolis Mine is extracting the Vanport Limestone in northeastern Ohio. Since the start of mining in 2006, ground conditions have been significantly affected by excessive lateral stress condition. In some other mining districts with this hazard, certain mine layouts have been shown to lessen the potential for unstable ground conditions. The term “lessen” is used to state the realization that stress concentrations are not eliminated but instead occur in less frequency and intensity, and their locations can be projected.The stress-control mine layout, specifically for large-opening room-and-pillar stone mines, naturally evolved at mines suffering from excessive lateral stress problems. These mines will typically experiment with methods to mitigate adverse impacts, thus developing best practices for their conditions. These practices have evolved into a basic framework for the stress control mine layout. For example, Jack Parker was able to write about personal experiences at the White Pine Mine in Michigan (Parker, 1966, 1973). Various researchers at the U.S. Bureau of Mines (USBM), the Mine Safety and Health Administration (MSHA), and the National Institute for Occupational Safety and Health (NIOSH) have studied the effectiveness of stress-control mine layouts over a wide range of geologic conditions (Emery, 1964; Mark and Mucho, 1994; Iannacchione et al., 2003). While the stress control layout design approach has proven successful in many categories, it can be difficult to implement. For example, excessive stress conditions in crosscuts can put the ground control focused intervention at odds with ventilation and haulage constraints, thus limiting optimal crosscut size, shape, and location. Therefore, more information on the effectiveness of this approach is needed."

Jan 1, 2019