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By P. Bissert, L. Yan, D. Yantek

"Federal regulations require refuge alternatives (RAs) in underground coal mines to sustain life for 96 hours while maintaining an apparent temperature (AT) below 35°C (95°F). NIOSH research has shown that heat and humidity buildup is a major concern with RAs because they have a limited ability to dissipate heat, and high internal air temperature and relative humidity (RH) may expose occupants to heat stress. The heat transfer process within and surrounding an RA is very complex and is not easily defined analytically nor experimentally. To investigate heat and humidity buildup in RAs, NIOSH conducted multiple in-mine 96-hour tests on a 6-person metal-type RA, a 23-person tent-type RA, and a 10-person tent-type RA. The test results show that when moisture was introduced into the tests to represent perspiration and respiration from miners (wet tests), the average measured internal air temperature at midheight increased by 7.7°C, 9.4°C, and 10.5°C, and the RH approached 95%, 94%, and 88%, respectively. For the dry tests when no moisture was introduced, the average internal temperature increased by 8.4°C, 10.3°C, and 12.6°C, respectively. INTRODUCTION If an accident occurs in an underground coal mine, miners who cannot escape from the mine can enter an RA for protection from adverse conditions, such as high carbon monoxide levels. One of the main concerns with the use of mobile RAs is the thermal environment inside the RA. The metabolic heat of the occupants and the heat released by the CO2 scrubbing system will cause the interior air temperature to increase. Moreover, the humidity within the RA will increase through occupants’ respiration and perspiration and from the chemical reaction within the CO2 scrubbing system. The internal thermal conditions can subject miners to heat stress, which can lead to heat exhaustion, heat stroke, or even death depending on duration and magnitude of exposure. MSHA regulations require that RAs must be designed to ensure that the internal apparent temperature does not exceed 35°C (95°F) when the RA is fully occupied [1]. Apparent temperature (AT) is a temperature-humidity metric for the perceived temperature caused by the combined effects of air temperature, relative humidity (RH), and wind speed. It is used to assess the perception of indoor temperatures when workplaces are not sufficiently heated, cooled, or insulated to provide comfortable or healthy conditions. Before a mobile RA can be deployed at an underground mine for emergency usage, it must be tested to show that its internal AT when fully occupied will not exceed the 35°C (95°F) limit. For practical reasons, RA manufacturers usually conduct their tests at above-ground test facilities. To investigate RA thermal response in an in-mine environment, NIOSH conducted multiple 96-hour tests on a 6-person metal-type RA, a 23-person tent-type RA, and a 10-person tent-type RA in its underground coal mine facility. The work described in this paper could be used by RA manufacturers to determine a final temperature rise based solely on dry and time-reduced testing."

Jan 1, 2017

By R. V. Ramani, K. V. Raj, S. Bandopadhyay

The air flow problems in openpit mines are complex. Computational fluid dynamics (CFD) models can provide detailed information regarding air flow pattern, velocity distribution, temperature, and pollutant concentration in an enclosed domain of an openpit mine. A range of turbulent models can be selected with varying complexity and accuracy. Pollutant transport models, however, differ in their assumptions and structure as well as in the algorithms they use. As a result, predictions vary from model to model. This paper presents a study of pollutant transport in an actual openpit mine under a stable boundary layer. The objective was to test two turbulence models using similar geometry and the same input conditions and model constants. Measured data were used to compare the results of the two CFD models, namely, the kappa-epsilon (к-є) model and the Large Eddy Simulation model. Despite the complex synoptic situations, different meteorological input data and fast-changing conditions, the simulation results from both the models were in good agreement regarding the dispersion of pollutants.

Jan 1, 2015

By J. G. Groppo

Laboratory settling and filtration testing was conducted on wet processed fly ash in order to determine the applicability of conventional dewatering techniques to reduce the moisture content prior to drying. Settling tests showed that acceptable clarity (<1.5 g/l suspended solids) could be achieved after as little as 6 minutes of settling. After settling to a consistency of 40 weight % solids, continuous laboratory vacuum filtration testing produced a cake containing below 20% moisture with throughput exceeding 150 lb/ft2/hr.

Jan 1, 1997

By William Gleason

The numbers tell the story of this one. More than 50,000 people and 1,890 exhibitors took over the Las Vegas Convention Center Sept. 24-26 for the largest mining trade show in the world ? MINExpo. Inside the convention center, some of the largest machines used in mining were on display. Caterpillar, Liebherr, Komatsu and Hitachi displayed ultraclass offroad mining trucks and shovels. Atlas Copco and Schramm were among companies that rolled in mining drills and Bridgestone, Goodyear and Michelin were among the companies showing off the massive tires used by the trucks. Throughout the three halls and an outdoor display area, just about every kind of product, gadget or service used in the mining industry could be found on display somewhere.

Jan 1, 2012

By Yi Yang, Xiuzhu Su, Wei Sung Ng, Shuiping Zhong, Miao Chen

With over 260 tons of gold reserves, the Shuiyindong gold mine is one of the largest Carlin-type gold deposits in China. A particular challenge in the processing of the ore is the presence of carbonaceous compounds, which can cause substantial losses in recoveries via the preg-robbing and adsorption of gold. To investigate the structural properties of the native carbon and to compare between different characterization techniques for such compounds, pre- and post-flotation mineral samples containing 0.9–4.8% non-carbonate carbon from the Shuiyindong mine have been examined via mineralogical and thermogravimetric approaches, as well as spectroscopic techniques, including X-ray photoelectron spectroscopy (XPS), near-edge X-ray absorption fine edge structure spectroscopy (NEXAFS), solid-state 13C nuclear magnetic resonance (NMR) spectroscopy, diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy, Raman spectroscopy and preg-robbing measurements. NEXAFS and DRIFT yielded the most reliable results, indicating that 60–75% of the organic carbon in all samples consist of aliphatic alkenes with substantial unsaturated content, highly similar to activated carbon, with the remainder being graphitic and humic. Speciation by XPS was sub-optimal due to spectral overlaps between graphitic and aliphatic carbon, and between carboxylic and carbonate functionalities, while NMR spectroscopy could not provide reliable speciation of the carbon groups. The preg-robbing strength was strongly correlated to the aliphatic content and structural disorder in the carbon, while no such relationship was found with the graphitic and humic content.

Nov 29, 2021

By E. W. Greig

This paper is an account of exploration for bauxite in the Amazon Basin, Brazil, and particularly of the discovery, exploration and development by Alcan of the Trombetas deposit so a general account of the Trombetas Project has already been published in E/MJ (Anon. 1975) to which the reader is referred for details on owner-ship, infrastructure and construction as well as the proposal for mining and treating the bauxite. It is impossible to consider the Trombetas deposits in isolation. A regional account of bauxite in and around the Guyana Shield and the northern portion of the Brazilian Shield is included and it is suggested that these deposits all formed during Tertiary time under similar conditions.

Jan 1, 1977

By T. B. Thompson

The Leadville District has been a prominent metal producer since its discovery in 1860. Veins and replacement bodies both have contributed to district production. The latter have been the major metal sources and are hosted within the Paleozoic Leadville, Dyer, and Manitou Dolomites. Igneous bodies representing eight separate events cut the sedimentary section. The main intrusive complex within the district occurs in the Breece Hill area and was the thermal center about which the vein and replacement ores exhibit mineralogical zoning. Precious metal-pyrite-quartz veins (quartz Th= 422 to 469°C; salinity < 4.2 wt. percent eNaCI) occur within or peripheral to the Breece Hill Intrusive Complex, whereas base metal veins and replacement bodies extend from the complex margins outward as much as 2 mi. Pre-ore and post-ore igneous bodies occur, but Fragmental Porphyry dikes immediately post-date the ore event. The Fragmental Porphyry grades downward from a heterolithic breccia with rock-flour matrix to one with a dark, glassy, sulfide- and phenocryst-bearing matrix, commonly with quartz-feldspar porphyry selvages on the dike. Two types of replacement bodies are recognized in the district: 1) the Leadville-type (LTM), massive sulfide (> 60% sulfides) bodies with recoverable Zn, Pb, Ag, and Au, and 2) the Sherman-type (STM), sulfide bodies (low total sulfide) with barite, galena, sphalerite, argentian tetra.hedrite, and minor pyrite. The latter type occurs only within the Leadville Dolomite and is found throughout the Mosquito Range and extending into the Alma District. The Leadville-type replacement bodies are zoned with a pyritic margin and base metal core. Wallrock alteration and trace Pb-Zn dispersion are strongly developed in igneous wallrocks but are weakly developed in carbonate wallrocks. Cu:Zn, Ag:Zn, and Au:Fe ratios increase outward from the center to the margins of LTM. Some of the sulfide bodies are localized on earlier-formed magnetite skarns. Pyrrhotite, pyrite, and marcasite are the earliest formed sulfide phases while chalcopyrite, marmatite, and galena developed later. Tetrahedrite and electrum occur in vugs and fine veinlets cutting the sulfides. Late-stage barite, dolomite, and fluorite occur as minor phases. Pressure-corrected Th for quartz (375-410°C), sphalerite (374-387°C), barite (320-360°C), and dolomite (310-314°C) fluid inclusions with salinities < 5.2 wt. percent eNaCI characterize the fluid responsible for the formation of the Leadville-type orebodies. These values clearly demonstrate the high temperature and low salinity of the ore fluids. Sulfur isotope analyses for galena and barite from LTM are - 1.9 to + 0.9%o and 7.8%o, respectively. Proximity to feeder veins and favorable dolomite hosts are the principal controls on ore localization. The Sherman-type bodies are not internally zoned but commonly have host rock silicification near the orebody margin or in the footwall rocks adjacent to fluid flowpaths along faults. Early quartz, pyrite, dolomite, and white barite precede base metal-silver minerals which are followed by late quartz and golden barite. It is not clear whether the early quartz and the late quartz and barite are part of the STM-forming process. Fluid inclusion analyses yield trapping temperatures as follows: early quartz, 316-341 °C; barite, 264-347°C; low-iron sphalerite, 215-265°C; and late quartz, 260-278°C. All inclusion fluids have salinities < 8.1 wt. percent eNaCI. Sulfur isotope values for barite and galena from STM range from 13.2 to 24.00/00 (avg: 18.4%o) and -6.8 to -3.8%o (avg: -5.5o/00), respectively. A hydrothermal fluid d34SSS of about 15%o is needed in order for galena and barite in equilibrium to exhibit the observed sulfur isotope compositions. Equilibrium sulfur isotope fractionation between barite and galena indicates a 300°C temperature of deposition. Two separate hydrothermal events appear to have taken place to form the distinctive Leadville-type orebodies and those of the Sherman-type assemblage. The STM is known to be older than the LTM. The latter is likely mid-Tertiary in age, post-dating emplacement of the Johnson Gulch Porphyry. LTM is clearly related to meteoric leaching of sulfur and lead (and other metals) from the upper portions of the Breece Hill Stock. Fluids were transmitted along faults, bedding planes, and contacts, and cooled away from the intrusive complex. Early ore fluids were weakly acidic and developed argillic assemblages in the igneous rocks adjacent to the fluid conduits. Reaction/replacement of carbonate rocks occurred where fluids encountered dolomite, but rapid neutralization prevented any wide-spread alteration beyond the ore-carbonate host contact. Pressures based on sphalerite geobarometry and stratigraphic reconstruction were 1.0-1.2 Kb. The high temperatures of vein and replacement ore fluids indicate that chloride complexing was more effective in metal transport than bisulfide complexes. Cooling, dilution of ore fluids, and reaction with carbonate rocks were the major factors in LTM ore deposition. STM formed over wide expanses of the Leadville Dolomite terrain adjacent to (and possibly capping) the Sawatch uplift. Sedimentary sulfur was derived from Pennsylvanian evaporite-bearing sequences adjacent to the uplift. Ore leads are strongly radiogenic (J-type) and are compatible with a crustal-leaching model. Temperatures of ore formation are higher, and ore-fluid salinities are lower than Mississippi Valley-type ore fluids. Superimposed upon dark-gray, diagenetic Leadville Dolomite are several stages of hydrothermal dolomite regionally distributed astride intrusive centers of the Colorado Mineral Belt. The presence of these later dolomites argues for dolomitization and later ore deposition in response to an abnormal thermal gradient caused by emplacement of Laramide batholiths and their generation of convective flow of meteoric fluids.

Jan 1, 2013

By Robert D. Saltsman

The inadequacy of our knowledge of the coal combustion process has long been recognized. This was expressed very well by Spicer and Finney (1). "The control of combustion processes in industry and the design of the equipment necessary for efficient burning to take place have always been very much branches of an industrial art rather than of an exact science. This has been especially true of the utilization of coal, a substance so hetrogeneous and complex in character that all too little is known about its chemical and physical composition.&apos; During the past several years one branch of coal utilization, that of high temperature carbonization; has made significant advances from being an art into being an exact science. This has been accomplished by the development of petrographic techniques for identifying, measuring, and determining the thermal properties of the organic materials which affect the carbonization of coal and the correlation of this information with a pre-existing standard of coke quality, the stability index.

Jan 1, 1964

By Amir Karami, Scott Munro

This paper focuses on remediation of a 3.6 km long water conveyance tunnel that suffered two large falls of ground (FoGs), one of which subsequently progressed to the ground surface, resulting in full collapse of the tunnel. The tunnel is part of a network of water conveyance tunnels and open channels that direct water into two turbines located in an underground powerhouse, originally constructed in the 1970s. At the time of construction, the tunnel was partially supported with shotcrete or rock bolts, with no further ground support added since construction. Two sonar surveys in 019 and 01 identied two adacent large FoGs in the tunnel, approimately 1.2 km from the tunnel outlet. Historical geological and geotechnical information indicated that the FoGs occurred within a 60 m wide fault zone. Remediation plans were developed, which included stabilization of the outlet channel, the portal, the tunnel leading up to the FoG areas (1.2 km length) and the FoG areas. Several remediation options were considered to restore the tunnel, including construction of a diversion tunnel to bypass the FoGs or remediation of the FoG areas with steel ribs and backlling the void above the FoGs to surface.

Jun 23, 2024

By J. Richard Kyle

The Pb-Zn ore bodies in the Pine Point district are localized in paleo-solution structures that developed as the result of post-middle Givetian subaerial exposure of the carbonate barrier complex. Sulfides are concentrated in transgressive pale-solution structures that acted as natural bypasses between aquifers and loci for mixing of fluids of different character, one of which contained metals and the other reduced sulfur. Complex ore textures indicate rapid early sulfide precipitation followed by slower sulfide growth. Evidence for both sulfide-carbonate equilibrium and disequilibrium conditions suggest fluctuations in ore fluid composition. District and ore body metal distribution patterns may reflect the nature and movement of mineralizing fluids.

Jan 1, 1979

By Gilbert C. Robinson

Manufacturers of brick and tile are showing growing interest in the possibility of manufacture of a clay bonded block. The block would have the shape of concrete block, but would be made without the use of Portland cement, Instead, the block would be made&apos; from mixtures&apos; of an aggregate and the present raw materials of the brick industry. The finished units would weigh 20 to 30 pounds and meet the specifications for Grade A concrete block. The present status of the clay block development shows one manufacturer actually in production of these units$, two additional manufacturers are attempting production and many manufacturers are actively engaged in development work. At least four major research laboratories are engaged in the development program. There are several different processes available for clay block production. These processes differ primarily in the type of aggregate used or in the type of forming operation selected. I would like summarize these possible methods.

Jan 1, 1960

By H. Sevim

Three transportation and handling alternatives for delivering dry coal combustion residues from power plants to underground coal mines were evaluated technically and economically. The objective was to transport, handle, and inject the residues into the old workings of the mine at a minimum cost. This objective was accomplished in two steps: I) Simulation models were developed and utilized in identifying technically feasible designs in each alternative, 2) Technically feasible designs were economically evaluated to obtain the cost-per-ton of material transported. The designs that provided the minimum cost-per-ton were declared optimal An analysis was conducted for varying distances and tonnages to reveal favorable operating ranges of each alternative.

Jan 1, 1996

By Albert R. Rule

Beneficiation studies were made by the Bureau of Mines to develop a process for concentrating phosphate minerals from the altered rock of the Phosphoria Formation. This report describes research on intermediate - and marginal-grade ores from southeast Idaho, The process developed consists of attrition scrubbing and sizing to produce a coarse concentrate; desliming at about 800 mesh (18.5 microns); flotation of the fine sands; roasting of the combined concentrates for removal of organic carbon and combined water; and leaching with SO2 for removal of magnesium and nonapatitic calcite. Results of continuous tests on three different ore types showed that approximately 80 percent of the available phosphate can be recovered at a grade suitable for phosphoric acid production. While leaching with SO2 is not necessary for all ore types, it is an important step in purifying concentrates containing excessive magnesium.

Jan 1, 1966

By David W. Wisecarver

The U.S. Bureau of Mines, in cooperation with U.S. Borax and Chemical Corporation and the Kennecott Copper Corporation, has investigated the use of the microseismic method to evaluate the stability of large, open-pit slope walls. The method is based on the phenomenon that stressed rock normally emits subaudible rock noises, and the number of rock noises per unit time (noise rate) and the magnitude of the rock noises (amplitude) increase as the stresses in the rock approach the failure stress of the rock. Therefore, the detection and recording of those rock noises serve as a semiquantitative method of predicting the incipient failure of rock. This report briefly describes the three different types of microseismic apparatus, the procedures, and the results of microseismic investigations in the slope walls of the Boron Mine near Boron, California, and the Rimbley, Liberty, and Tripp-Veteran open-pit mines near Ely, Nevada. Microsesimic noise rates in stable inactive mining areas are between 0 and 10 noises/ hour; the rates in stable active mining areas are between 10 and 50 noises/hour; and the rate in unstable areas is as high as 2500 noises/ hour. High microseismic noise rates in the Liberty Pit correlate with the time of nearby earthquakes, indicating that the earthquakes affected the slope wall. The results provide evidence that the microseismic tech¬nique is applicable to large pit walls, and that the wide band, wide range microseismic equipment appears to be suitable for open-pit investigations.

Jan 1, 1969

By R. A. Ynchausti

In January 1993, Pyramid Resources began implementation of a supervisory expert control system at a U.S Cu concentrator. The objective of this control system was to improve plant profitability through unit operation optimization and integration. This paper documents the key aspects of the project, including: economic and associated benefits, system architecture, concepts of implementation, process control strategies, practical aspects of implementation and conclusions. The implementation of expert control at this concentrator has resulted in an estimated benefit of $50,500 per day. This is a net result of improved tonnage, reduced reagent consumption, improved concentrate grade and reduced energy per ton produced.

Jan 1, 1995

By Kallam V. K. Reddy, VADAPALLI SANJANA, Veerendra Singh, Gajanan Kapure

This work describes a leaching process for the conversion of high-magnesium peridotite rock, which is a chromite ore overburden, into two valuable products: magnesium salts and micro silica. Under normal leaching conditions, residue remaining after leaching is of a gelatinous nature and thus hinders the filtration process. To address this issue, oxidative leaching with the addition of H2O2 was employed, and it significantly improved the filtration kinetics. Four different approaches for H2O2 addition were tried, and they all proved effective in controlling gelation. The optimum oxidative leaching condition was 70 °C, 2 h time, 2 M H2SO4, 0.5MH2O2 and 400 RPM; under these conditions, 92% magnesium leaching efficiency was achieved. After leaching, the leach liquor obtained was purified and dried into Mg(OH)2 and MgSO4 salts. The leach residue contained mainly silica particles, with size in the 10–30 μm range. This material thus represents an attractive candidate for the production of highperformance concrete for the construction industry. The oxidative leaching process described here enabled the complete conversion of peridotite into valuable products, magnesium salts and micro silica.

May 5, 2020

By Anil K. Ray

Roof falls are one of the greatest hazards in underground coal mines worldwide. Due to stringent safety measures and extensive support system development, roof falls have been reduced significantly but they still persist in many underground coal mines. Some of the roof falls initiate with cutter roof or guttering. In the past, many factors have been identified as being responsible for the development of cutters and roof fall. These responsible factors can be broadly classified as stress related or non-stress related. In this paper the finer details of mining technique have been taken into consideration for better understanding of cutter roof and roof fall problems. Three dimensional finite difference modeling has been used to explain the mechanism of cutter development. Strain softening material behavior has been used to realistically simulate the cutter formation, and common cutting sequences as implemented in the field have been simulated. This was done with an objective to determine whether the cutting sequence has really any significant control over cutter formation or not. In addition to cutting sequences, the effect of cut length is also studied. The effect of step cutting and turning of crosscut into and away from major and minor horizontal stresses is also examined to see its influence on cutter development.

Jan 1, 2009

By Frank P. Frandina, Diane R. Hirsch, David P. Field, Colin R. Weeks

To accommodate growth in air service and to follow the Master Plan for long-term airport development, the Metropolitan Washington Airports Authority established thed2 Development Program at Washington Dulles International Airport. A sub-surface Automated People Mover (APM) System is under construction to replace the Mobile Lounges as the primary people mover system at Dulles. To minimize disruption to airport operations the majority of the APM System’s crossings of Taxi lanes will be undertaken using Tunnel Boring Machines (TBM) or the New Austrian Tunneling Method (NATM). This paper explores the planning and design of these shallow tunnel segments for future generation aircraft loads, within the constraints of minimal construction access under post 9/11 security requirements and the context of the overall airport expansion program.

Jan 1, 2005

By G. S. Austin

Soil next to an abandoned smelter near Socorro, New Mexico, has the highest Pb concentration in the clay-size fraction, although this fraction accounted for only 1 to 3 wt. % of the soil. The depth of contamination was determined in areas relatively undisturbed since the smelter was abandoned about 98 years ago. Lead concentration drops to background levels below a depth of 3 inches. A mineralogical examination of the fine-size fraction of Pb-contaminated soils revealed an absence of crystalline Pb compounds. We conclude that Pb is present either as amorphous phases or adsorbed on the surfaces of soil particles. Yet, because of the alkalinity of the soil, the movement of Pb-bearing particles controls Pb mobility, not chemical transport in solution. Plant material from the site contained elevated Pb levels that increased as the amount of Pb in the soil increased. Of the types of material tested, rabbit bush showed the greatest increase of Pb levels. Lead levels were highest in rabbit bush roots, whereas levels in creosote were highest in foliage. Levels in cactus varied. The amount of Pb due to dust incorporated in plant tissue is almost negligible compared to the amount absorbed through the plant vascular system.

Jan 1, 1992

By Drew A. Meyer

Magnetic metals are the granddaddy of products which may be recovered from municipal waste. Aside from hand-picking of newsprint and corrugated boxes, magnetic metals are usually the first items a resource recovery facility considers extracting from the solid waste stream. Magnetic metals from incinerator residues and from municipally mandated source segregation programs were first used in significant quantities by the Copper Industry. The ability of the Copper Industry to consume metals from the municipal solid waste stream raised everyone&apos;s hopes that there would be more markets for municipal scrap when more of it became available. Somehow something has gone wrong. It is widely acclaimed that scrap is an environmentally sound and economical source of iron. It is greatly in demand for Its contained energy. The prices that the steel industry has been willing to pay for the scrap during the past year are all the proof anyone should need that scrap Is desirable and sought after. But the very fact that I&apos;m speaking today on the markets for magnetic metals recovered from municipal waste indicates that something Is wrong. Clearly the problem is not that we do not need the scrap. The problem is we have not produced the kind of scrap that consumers are willing to buy - either through ignorance of what the consumers wanted or through a conviction that ferrous scrap is so obviously a good thing somebody will surely want it no matter what. Dr. Harvey Alter of the National Center for Resource Recovery has said "You can&apos;t sell garbage". In a sense that is only partly true. It really should be "You can&apos;t sell garbage for very long". The Steel Companies, in an effort to prove that steel is an environmentally desirable packaging medium, have bought some scrap that can only be described as garbage. They are to be commended for doing so. The fault lies not with the Steel Company for taking and paying for "garbage" but with the producer of that poorly prepared scrap. Far every instance where the steel industry has purchased the often undesirable product from resource recovery facility there are several magnetic installations sitting Idle because someone forgot the most essential part of producing the magnetic product - selling it to someone.

Jan 1, 1975