Search Documents

By Douglas A. Anderson

Mine the Internet? You bet. Precious information resources are there to be found by those willing to explore. Of course, the stratigraphy and the exploration tools must be learned. This article is is designed to help learn those tools and how to find the information that can help the reader. However, beware the Internet. It can be addicting. On the other hand, information can be found that you never suspected. And users can make contact with people who might otherwise never have crossed their paths.

Jan 1, 1996

By R. Tamblyn

Vertically stirred media mills are a highly effective low-footprint solution for the ultrafine grinding of industrial minerals. This work investigates the effect of media density on flow patterns within the mill. Direct irradiation of a media particle leads to decay through positron emission, consequently forming two anti-parallel gamma rays, which allow for the real time tracking of particle position. Grinding media of the same size, but with a range of specific gravities are followed using this method, and the effect on the flow within the mill is revealed. The technique is seen to be an effective method to highlight the velocity profiles within the mill, as well as the zones where grinding is less efficient ? areas of relatively low velocity and high residence time. The changing media is seen to effect the overall flow patterns within the mill, having consequential effects on the efficiency of the grind.

Jan 1, 2009

By Arash Nikvar‑Hassani, Timothy Batchler, Lianyang Zhang

Recently, a new hybrid geopolymer/biopolymer (GP/BP) cementitious material was developed for improving the performance of pumpable roof supports in underground mines. This study demonstrates the application of the hybrid GP/BP cementitious material and validates its effectiveness in full-scale. In this regard, eight (8) full-size (0.61 m diameter and 1.52 m height) cribs were produced in collaboration with Minova International Ltd and tested at the National Institute for Occupational Safety and Health (NIOSH) Mine Roof Simulator (MRS) Laboratory. These full-size cribs were produced with different material configurations to evaluate the effect of water to solid (W/S) ratio, Portland cement (PC) content, and BP dosage. The results demonstrated and validated the effectiveness of the hybrid GP/BP cementitious material in increasing the peak and residual bearing capacities of pumpable cribs and eliminating the issue of deterioration when exposed to air compared with the conventional Portland cement/fly ash (PC/FA) cementitious material currently used in practice. On average, the peak uniaxial compressive strength (UCS) and the highest residual UCS after peak of the full-size cribs produced from the hybrid GP/BP cementitious material are 1.90 and 1.33 times of those of the PC/FA-based full-size cribs by one company and 2.32 and 1.66 times of those of the PC/FA based full-size cribs by the other company, respectively.

Feb 6, 2024

By Jon A. Hummer, MICHAEL R. SHAHAN, Aleksandar D. Bugarski, Shawn Vanderslice

A study was conducted in an undergroundminewith the objective to identify, characterize, and source apportion airborne aerosols at the setup face and recovery room during longwall move operations. The focus was on contributions of diesel- and battery-powered heavy-duty vehicles used to transfer equipment between the depleted and new longwall panels and diesel-powered light-duty vehicles used to transport personnel and materials to various locations within the mine. Aerosols at the setup face were found to be distributed among diesel combustion-generated submicrometer and mechanically generated coarse aerosols. According to the data, the submicrometer aerosols downstream of the setup face were sourced to diesel exhaust emitted by vehicles operated inside and outside of the panel. Depending on the intensity of the activities on the panel, the outby sources contributed between 12.5 and 99.6% to the average elemental carbon mass flow at the setup face and recovery room. Extensively used light-duty vehicles contributedmeasurably to the elemental carbon concentrations at the setup face. The number concentrations of aerosols downstream of the setup face were associated with aerosols generated by combustion in diesel engines operated in the shield haulage loop and/or outside of the longwall panels. Entrainment of road dust by diesel or battery-powered load-haul-dump vehicles operated near the measurement site appears to be the primary source of mass concentrations of aerosols. The findings of this study should help the underground mining industry in its efforts to reduce exposures of miners to diesel and coarse aerosols.

Apr 14, 2020

Komatsu America has introduced its 2-MW (2,700-hp), 930E-3 ac electric drive truck with a 290-t(320-st) capacity. The truck is designed to provide increased productivity, lower cost per ton hauled and improved speed and control. The 930E-3 is powered by a Komatsu SSDA16Vl6016-cylinder engine. It is capable of speeds up to 65 km/h(40 mph) and is a 15-percent to 20-percent more productive unit than 218-t (240-st) trucks, at a lower operating cost per ton. The 930E-3 also provides enough torque and speed to get up and off ramps easier than mechanically driven trucks. And it can climb at altitudes up to 3,650 m(12,000 ft) without any fuel deration.

Jan 1, 2004

By S. Frimpong

Shovel excavation constitutes a significant component of production costs in any surface mining operation. This makes shovel loading an important cost center that needs to be improved to lower production costs. Optimization of tool design will improve energy efficiency in earthmoving operations. However, modeling the soil-tool interaction is a complex process due to the fact that forces for excavating particulate material are functions of many variables. The magnitude of this resisting force depends not only on the type of soil but on the size, shape and orientation of the cutting element. Moreover, part of this complexity is attributed to the fact that the behavior of the material during excavation is not yet well understood. For the past five decades, researchers have mostly used the passive earth pressure theory to study the soil failure patterns around a cutting tool and to develop force prediction models for design optimization with some success. Although the force models developed from the passive pressure theory have been successful to some extent, they can hardly be extended to a general case because of the underlying assumptions and simplification of tool shapes. This paper aims at reviewing some of the existing empirical and analytical methods of cutting and excavation tool modeling with a focus on their merits and limitations. The paper also explores the use of numerical methods, specifically the discrete element method, for dealing with the unresolved aspects of soil dynamics in excavation.

Jan 1, 2011

This geometallurgical study examines the gangue mineral variability at the Bingham Canyon porphyry copper mine in Utah. Understanding an orebody?s mineralogy is important for mine and mill planning because it provides information on the size, texture, and distribution of ore minerals, the relationship between ore and gangue minerals, and the extent and type of alteration. Quantification of the mineralogical variability and properties of an orebody provides valuable input to the ore model and may have a significant effect on recovery optimization. This study was designed to be carried out on an initially detailed scale in order to develop a robust methodology for measuring and quantifying specific parameters, such as the distribution of mineral phases, alteration assemblages and fractures from key ore domains at the Bingham Canyon mine (Figure 1). Details of the methodology are reported below. This technique can be applied to testing the impact of mineralogy on a number of processing parameters. [ ] Figure 1. Ore domain map of Bingham Canyon (Kennecott Utah Copper, 2003) showing the 33 geometallurgical ore domains. The samples for this study were collected from the northwest part of the deposit circled on the map. PROJECT BACKGROUND Geology The Bingham Canyon deposit is a large porphyry Cu-Mo-Au deposit with associated skarn and base-metal replacement deposits mined in an open-pit mine measuring about 2.5 miles across and 4,000 feet deep. The deposit is hosted by the Bingham Stock, a Late Eocene to Mid-Oligocene intrusive complex. The skarn is hosted by the Late Carboniferous-age Bingham Mine Formation, which is comprised of quartzites and basal limestones (Babcock Jr. et al., 1998). The Bingham Stock is a composite intrusive complex that was emplaced over a period of about two million years. The oldest phase is described as a fine-grained equigranular monzonite (MZ), which intruded the country rocks at 39.8 ± 0.4 Ma (U-Pb zircon TIMS age) (Parry et al., 2001). Subsequently, the quartz monzonite porphyry (QMP) was emplaced, followed by intrusion of a latite porphyry (LP). The final intrusive phase, which forms narrow dikes that crosscut the Bingham Stock, is represented by a quartz latite porphyry (QLP), which is dated to 37.5 ± 0.4 Ma by 40Ar/39Ar dating of sanidine (Deino and Keith, 1998). Also present, are a minette dike in contact with a QLP dike (Waite et al., 1998; Deino and Keith, 1998), and a biotite porphyry (BP), a quartz latite porphyry breccia (QLPbx), and a pebble dike (Redmond, 2002). The copper orebody is centered above the Bingham Stock and forms an inverted cup shape with three high-grade copper zones extending to depth. Molybdenite mineralization occurs within and extends below the copper orebody, but is not correlated with copper mineralization. The main sulfide assemblage is chalcopyrite, bornite, molybdenite, and pyrite. Gold is locally intergrown with chalcopyrite and bornite (Babcock Jr. et al., 1998; Phillips et al., 1998). The surrounding country rocks host skarn deposits with three main ore types - garnet skarns, massive sulfides, and iron oxides. The garnet skarns contain chalcopyrite and pyrite with magnetite veins. In the massive sulfides chalcopyrite and pyrite occur either in banded sulfides or in unconsolidated microbreccias. The iron oxides contain disseminated chalcopyrite with minor chalcocite and bornite (Harrison and Reid, 1998). The deposit is overprinted by several stages of alteration. Potassic alteration is concentrated at the center of the deposit. It is surrounded and partially overlapped by a propylitic alteration zone. Both zones are overprinted by sericitic alteration. In the northern part of the deposit evidence for argillic alteration can be found (Bowman et al., 1987). Similarly, the skarn deposit was also overprinted by several stages of alteration: wollastonite, idocrase, and garnet in cherty limestones, and quartz and diopside forming in calcareous quartzites. Distally, diopside was replaced by talc, tremolite, dolomite, secondary calcite, and pyrite, and quartz and sulfide veinlets with biotite and actinolite selvages are present. Andradite garnet, diopside, quartz, magnetite, hematite, and copper sulfides were overprinted by wollastonite (Babcock Jr. et al., 1998). Because the monzonite, quartz monzonite porphyry, latite porphyry, and quartz latite porphyry host the bulk of the mineralization, our research is focused on these lithologic units. Geometallurgy On the basis of geological (lithology, alteration assemblages, fracture density, copper mineralization) and metallurgical properties, the deposit has been divided into 33 ore domains by mine geologists and metallurgists (Figure 1). In map view, these domains cross geologically defined boundaries (MZ, QMP etc.). These domains reflect regions of the deposit that have particular, mapable attributes or properties. They reflect a combination of geological and mineralogical characteristics that combine to impact processing. Alteration, for example, as shown by talc mineralization, is one such key feature. Hardness may reflect the absence of sericitic but presence of potassic alteration. Structural discontinuities such as faulting, fracturing, or development of void

Jan 1, 2009

By S. M. Carpenter

In response to the FY2008 Consolidated Appropriations Act (H.R. 2764; Public Law 110?161), the United States Environmental Protection Agency (USEPA) issued the final Mandatory Reporting of Greenhouse Gases Rule (MRR). The rule, signed by the USEPA Administrator, Lisa Jackson, on September 22, 2009, requires reporting of greenhouse gas (GHG) emissions from large sources and suppliers in the United States, and is intended to collect accurate and timely emissions data to inform future policy decisions. The MRR will go into effect on January 1, 2010, and a report of the total emissions for calendar year 2010 will be due to the USEPA by March 31, 2011. Under the final MRR, suppliers of fossil fuels or industrial greenhouse gases, manufacturers of vehicles and engines, and certain facilities that emit 25,000 metric tons or more per year of GHG emissions are required to submit annual reports to the USEPA. The gases covered by the rule are carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), hydrofluorocarbons (HFC), perfluorocarbons (PFC), sulfur hexafluoride (SF6), and other fluorinated gases as outlined in Table A-1 of Subpart A of the MRR, which is also provided in Appendix A of this report.

Jan 1, 2011

By C. Asgaard

Asset availability has been a longstanding objective in mining and mineral processing plants around the world. Enormous resources in both dollars and manpower are invested in improvement efforts to achieve higher asset availability. One dimension of asset availability is the time equipment is out of service for large scale planned maintenance activity: grinding mills, kilns, furnaces, mobile equipment, shovels and draglines are all regularly taken out of service for extended repairs and service. The speed, cost and quality of these planned outages provide an opportunity to increase asset availability. Equipment shutdowns are projects that are executed in a compressed time period. This paper will describe how the overall time and cost of equipment shutdowns were significantly reduced at Cliffs Natural Resources Michigan Operations (CNRMO) through the introduction of the Critical Chain Project Management techniques.

Jan 1, 2009

By Brian E. Gombos

During early stages of the detailed design for Detroit?s Upper Rouge CSO Tunnel Project, a Value Engineering Recommendation suggested the design team investigate alternative concepts to the usual cast-in-place or precast concrete lining system for the Project?s many smaller diameter Deaeration Vent Shafts. The resulting design investigation produced not only an alternative lining system, but lead to a proposed non-conventional approach to shaft installation means and methods through soil and rock necessary to construct the permanent shaft lining system. This paper will outline and summarize the technical issues, contractual restrictions, and cost considerations that eventually lead to the final shaft design

By E. P. Deliac

The aim of this joint work between the French Coal Board and the Paris School of Mines is to be able to practically model the behaviour of a transverse drum cutting rock with picks. First a theoretical approach leads to the concept of cutting curves, giving forces and torque against penetration per drum revolution. Then experimental evidence, from full scale and reduced scale testing, validated and confirmed the theoretical shape of the curves. Finally practical applications are given, to improve the design or use of a shearer (or continuous miner). A micro-computer program is being developed to predict the cutting performances of a machine in certain conditions.

Jan 1, 1985

Effective tools are not only essential for the design of practical and efficient underground mine ventilation systems but must also play an integral part in the operation of the mine. One such tool is VUMA-coal ventilation simulation software. VUMA-coal is Windows-based and has been specially designed for the simulation of underground coal mines and includes user-friendly coal specific interfaces and three-dimensional graphics designed to facilitate in the construction and analysis of networks. VUMA-coal can be utilised during the design phase of new collieries, be used to conduct ?what-if? and optimisation studies, and be integrated into the ?day-to-day? ventilation related operations. In addition, VUMA-coal can be used to simulate dust and gas distribution in a ventilation network, as well as predict the impact of control measures. This paper describes the interactive VUMA-coal ventilation simulation software and its underlying design features and outlines a case study of how VUMA-coal has been integrated into Anglo Coal?s Ventilation and Occupational Hygiene Engineering [VOHE] department as part of the standard planning and evaluation process in their operational mines as well as long term planning and future mining operations.

Jan 1, 2009

By S. Dixon

The Peñasquito deposit in Mexico is one of the largest grassroots precious metal discoveries developed in recent years. Goldcorp Inc. acquired the gold-silver-lead-zinc property with the acquisition of Glamis in 2006. The Peñasquito property is located in the northeast corner of Zacatecas state, Mexico. The elevation of the property averages 1,900 m (6,200 ft) above sea level. It is situated in a wide east-west valley. Minera Peñasquito, S.A. de C.V., wholly owned subsidiary of Goldcorp Inc. has operated twin SABC-flotation lines since June 2010. Each line is capable of processing 50,000 tonne per day using a SABC grinding circuit followed by flotation to produce lead and zinc concentrates. The addition of a Polysius Polycom HPGR 2417 with dual 3,000 kW drives to reduce the crushed pebbles produced by the SAG mills was planned to increase production to 65,000 tonne per day per line. The production has been limited to 100,000 tpd due to operating issues in the grinding circuit. The operating issue has been the amount of pebbles generated by the SAG mills is significantly less than originally planned. This paper describes the planned installation of a crushed augmented feed to maximize utilization of the HPGR capacity. This coupled with full utilization of the SAG and Ball Mill available energies there is the potential to achieve a 50% total capacity increase from the grinding circuit.

Jan 1, 2012

By Gary Jackson

Preliminary engineering for the Waller Creek Tunnel was completed in 2001, but the project was held in abeyance until the summer of 2007. This paper describes several features of the revised design, which required significant changes from the original concept. Most notable is the expected replacement of a tunnel boring machine (TBM) by conventional tunneling. The considerable influence of geological conditions on the tunnel vertical alignment is discussed, in particular the impact of the zones of Eagle Ford Shale with swelling potential. Other features which are described include the wide span tunnels and large diameter shaft requirements.

By John B. Gustavson

This paper describes a case history of geochemical prospecting. An area of known mineralization was available for an orientation survey which led to the selection of elements and criteria for a reconnaissance survey in the area offsetting the known mineralization. Certain anomalies were found which were then made subject of confirmation sampling and of rock geochemical investigations. Inasmuch as the geochemical prospecting technique specifically led to a detailed area which now serves as a target for drilling and other exploration efforts, the geochemical prospecting part of the program is considered successfully concluded and, therefore, reported on here. Whether the target area will turn out to host the deposit or not is, of course, of utmost importance to the Company, but is of less importance to this paper. We will describe the concepts, the planning, the execution, the analysis and the interpretation of this typical geochemical prospecting case. A number of people on the staff of International Oil & Gas, Inc. have participated in this prospect, as have students from Southeast Missouri State University and their professor, Gary M. Lowell. In addition, the Missouri Geological Survey has been most helpful with records and letters on the century-old prospecting and mining in the general area. Many valuable discussions have also been held with geologists from the industry who, from time to time, have visited the area, examined the property and reviewed the status of the project. The support and interest from all these parties has made it possible to pursue and expand this exploration concept from one of being just "more of the same kind" to the most chal-1enging and exciting with which this author has ever been involved, namely the prospect for tin porphyry deposits in the mid-continent United States.

Jan 1, 1977

By Andrea B. Baldwin

In recent years, federal and state regulatory agencies have tightened air emission standards. Two of the acid gases, hydrochloric acid (HCI) and sulfur dioxide (SO2), are under heavy scrutiny for reduction. . Most traditional scrubbing systems, i.e. wet scrubbers and spray dryers, meet the standards but they typically are high in capital cost, have significant space requirements for equipment, and are difficult to maintain. Dry sodium injection (DSI) is a alternative technology that has been shown to be effective in HCl and SO2 removal while being the inverse to the problems listed with traditional systems. This paper covers the mechanics of dry injection scrubbing using the most effective sorbents, sodium bicarbonate and mechanically-refined trona (natural sodium sesquicarbonate). It presents DSI performance data for Chambers Medical located in Hampton, SC. This facility incinerates local medical and municipal solid waste. Chambers Medical has used mechanically-fined trona for HCl and SO2 removal since late 1991.

Jan 1, 1995

By J. K. Lemley

The human element in large measure dictates success in contracting relationships. Because of our professional backgrounds, we view contracts primarily as either engineers, contractors or owners. A beneficial contractual environment--one in which decisions, risks and benefits are shared--demands equal consideration of all three points of view. Most of the older cities in the United States, for example, suffer from bad contracts--generalized, patched-together documents that represent an accumulation of modifications originally written to compensate for specific situations that have occurred over the years. Because such documents lack coherence, they often present conflicting instructions which lead to defensive, ultimately destructive attitudes among the parties involved in the day-to-day administration of the project. Good contract development begins with a strong central philosophy to which the details of the contract can be related. First, the owner should establish a comprehensive philosophy in which risks between the parties are identified. Following this, a specific contract document can be written to satisfy this established philosophy. The contrast between two opposed contractual situations, NYC Water Tunnel Number Three and the Seabrook Nuclear Power Plant Cooling Water Tunnels, illustrates how comprehensive, well-written contracts--contracts which share both risks and benefits--provide the basis for achieving quality construction that will reward engineer, contractor and owner.

Jan 1, 1983

By J. Darlington, A. K. SenGupta

Water-swellable layered silicates, namely, the smectite clays can remove suspended materials (called herein as debris) and metal ions from aqueous streams. The present study shows that the flocculating and metal extracting abilities of smectite clay-based flocculants can be enhanced when these clays are used in conjunction with a specific anionic polymer. Such performance enhancement is attributed to the following: i) the clay-dispersing ability of the polymeric additive, that would translate into an increase in the clay-surface area available for the attachment of the debris particles onto the clay particles; ii) the possibility of dispersant-to-coagulant transition of the polymer during the later instants of the treatment process, as a result of reduction in solvency of the wastewater for the polymer due to the release of cationic species from the clay-based flocculant solids; iii) metal-complexing ability and adsorption properties of the polymer.

Jan 1, 2002

By Glen Frank, David R. Chapman

Determining the number of boulders and cobbles that will be encountered in the tunnel envelope is one of the most difficult problems confronting the geotechnical engineer in the design of tunnels in glacial terrain. This issue is very important to the contractor, both in determining what methods will be used to construct the facilities and the advance rate that can be achieved for the chosen construction methods. The cost of constructing tunnels by pressurized face tunneling techniques is very sensitive to accurate characterization of the very coarse fraction (large cobble and boulder sized clasts), and no standard method is current available for characterizing boulders and cobbles. Careful use of large diameter borings and the sampling and analytical techniques outlined in this paper can provide a means to answer this difficult question. By performing large diameter borings and carefully recording and sampling the cobbles and boulders encountered, an estimate for the amount of these materials present in the formations sampled can be provided. Using this method allows the designer to communicate the expected geologic conditions to the prospective bidders in a manner that is both definitive and defensible. This paper describes the method as it was used in conjunction with the design of a large diameter sewer tunnel in the Columbus, Ohio area.

Jan 1, 2005

By J. Humphries

With today?s turbulent markets and unprecedented global opportunities, the need to optimize net present value and internal rates of return from capital investments has never been greater. To help address the need, this paper presents an overview of the key processes and strategies for achieving maximum return from capital projects. Best practices discussed address stage gate management for project evaluation, selection, and oversight, project execution efficiency, value improving practices, operational readiness, and operational excellence. The paper also includes a model of key metrics and benchmarking with tips for application. [ ]

Jan 1, 2011