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By C. D. Harrison, G. S. Stallard

The 199O Clean Air Act Amendments specify national objectives for reducing sulfur dioxide emissions from coal fired power plants. System-wide reductions can be achieved by combining various emissions control technologies and allowances, or compliance credits, that can be purchased, sold or traded. As part of the Coal Quality Expert development project funded by the US Department of Energy and the Electric Power Research Institute (EPRI), Black & Veatch has developed an interactive computer tool, the Acid Rain Advisor (ARA). Through this program, integrated, system-wide compliance plans are generated by comparing the costs and emissions reduction benefits of emissions allowances and various SO2-control technologies (coal cleaning, fuel switching, scrubber retrofits, etc.)

Jan 1, 1993

By F. Vallianatos

The main objective of the present investigation is to demonstrate the potential of ERT (Electrical Resistivity Tomography) and HVSR (Horizontal to Vertical Spectral Ratio) methods as geophysical tools for the monitoring of subsurface cavities. The survey sites are located in Akrotirion Peninsula, almost 7 km east of Hania town in Crete Island, Greece. At this site, the surface expression of a known cavity with a diameter of about 25 m is visible. The true geometrical characteristics of the cavity were unknown since there are no boreholes in the area. The focus of this survey was primarily of a qualitative nature and the objective was to determine if ERT and HVSR could be used to identify and map near surface cavities (less than 30 meter in depth) in a limestones kartsic area such as Akrotirion Peninsula. A 2D/3D model of the resistivity distribution is given for the area under investigation. Furthermore, analysis of microtremors data provides a profile of the seismic response of the tectono-karstic voids.

Jan 1, 2006

By James W. Mahar

The following paper summarizes our observations on building response to mine subsidence and techniques for mitigation of building damage. The subsidence cases are located in Illinois. The general description of the geologic and mine conditions are primarily for those sites. Data on building response and mitigation measures were collected under grants supported by the Abandoned Mined Lands Reclamation Council (AMLRC) of Illinois and the U. S. Bureau of Mines, in Twin Cities, Minnesota. Case histories include pit and sag subsidence primarily beneath abandoned room and pillar mines. The majority of the paper deals with structures affected by sag subsidence. Most of the structures are one and two story homes. The first section of the paper summarizes the typical geologic and mining conditions at the sites. Building response to pit and sag subsidence follows the first section. Emphasis is placed on the behavior of concrete and masonry foundations, and wood frame and masonry superstructures. The third section describes mitigation techniques used to prevent or minimize building damage. A summary of the observations and critical parameters is given at the end of the paper.

Jan 1, 1982

By A. Vaillant

Classifiers that are used to separate granular materials into a coarse and a fine stream, are considered. Fundamental Equations are presented which apply to all, such Classifiers and all feed size distributions. The practical, real Classifier is compared quantitatively with the perfect. Classifier. A Formula is introduced for the Real Classifier Selectivity, that defines what portion of each particle size is sent to the coarse outlet duct. This selectivity function is characterized by three Parameters, one of which (b) is a numerical measure of the sharpness of classification. A new dimensionless variable (J) appears in Equations and Graphs for recirculating load, product size distribution and specific surface in the classified product. This variable combines the effects of sharpness of separation, Classifier setting and fineness of a Rosin-Rammler Type feed to the Classifier. Classifier efficiency is defined, based on Specific Surface.

Jan 1, 1967

By W. M. Hart

The current Automatic Data Acquisition system developed by some support manufacturers makes it possible to continuously monitor and record changes in leg pressure and advancing ram stroke in every shield, and shearer position at any moment during the mining operation. In order to effectively use the massive data obtained from this system for improving production and maintenance managements as well as providing better roof control at a longwall face, the research currently conducted jointly by West Virginia University and Cyprus-Amax Coal Co. attempts to develop a Longwall Management System for mine operators. The LMS software package runs on a MS Windows NT environment and consists of four sub-systems: (1) Data Interpretation and Analysis; (2) Production Management; (3) Maintenance Management; and (4) Ground Control. This paper presents the details of each sub-system.

Jan 1, 1995

By K. W. Grubaugh

The recently enacted federal surface mine law (P.L. 95-87) will increase further the complexity of securing a reclamation permit. This law intensifies the need to present the required reclamation plan in a thorough and comprehensive manner. One plan format, that used in construction performance contracts, offers promise of filling this need. Reasons for using the format of expressed, bilateral, negotiated contracts common to the contruction industry, and the salient aspects of an application which uses this format are reviewed. Advantages of this procedure are seen to be improved mine planning, awareness of the total design job, potential for improved speed of permit acceptance and improved cost control.

Jan 1, 1978

By D. K. Marjaniemi

The U.S. Bureau of Mines inventoried and characterized mineral sites and production plants within 200 km of the border in both the U.S. and Mexico. Sources of information included the USBM Minerals Availability System, the USBM Automated Mineral Information System, the USGS Mineral Resources Data System, the Mine Safety and Health Administration Address/Employment File, and the literature. Three hundred seventy-eight major construction material and industrial mineral properties were identified and characterized in the U.S. and Mexican parts of the Borderlands. Sixty-six major metallic mineral properties were identified and characterized in the Mexican part of the Borderlands.

Jan 1, 1996

By B. Seymour

The National Institute for Occupational Safety and Health (NIOSH) is conducting research to develop safe practices for the use of shotcrete as ground support in underground mines, particularly mines operating in weak host rock. As part of this research, tests were conducted with a commercial poly-fiber reinforced shotcrete mix to develop a practical means of measuring shotcrete adhesion strength. Full-scale tests were conducted in a test frame equipped with concrete panels having three distinct surface roughness profiles. Adhesion test fixtures either embedded or epoxied in the shotcrete were overcored into the underlying concrete, and direct tensile tests were conducted to determine the bond strength of the shotcrete cores to the substrate after a selected shotcrete curing interval (1, 3, 7, 14, 28, or 90 days). Measured adhesion strengths typically ranged from 0.5 to 2.0 MPa depending on the curing age of the shotcrete samples. This paper presents the results of these tests, describes the portable test system components, and addresses some of the design issues encountered in the development of a rugged and reliable method for determining shotcrete adhesion strength in underground mines.

Jan 1, 2010

By S. Potgieter-Vermaak, T. T. Chiweshe, W. Purcell

Complete isolation of chromium (III) from the reference material (SARM 131), Upper Group 2 (UG2) chromite ore, and Merensky Reef mineral ore was achieved using ammonium phosphate salt as flux. Optimum pH (3.2–3.8) conditions and sample to flux ratios (1:25) were some of the factors that were critical for the complete isolation of chromium. Increasing the sample to flux ratio (1:50 excess) however resulted in the conversion of all the elements in the melt into a green solution (pH, 5.8–6.7). A different chromium compound was subsequently isolated from the green solution by allowing this solution to stand in an open vessel in a cupboard for a month during which time the pH decreased to pH 3.5–4.2. Quantitative analyses of chromium from the isolated precipitates of SARM 131, UG2 chromite ore, and Merensky Reef mineral ore indicated chromium contents of 41.87, 60.41, and 23.93% respectively which were very close to the chromium content in the original samples. Analysis of the chromium precipitates using IR indicated the presence of phosphates (1100–1200 cm−1 ) while SEM-EDX analysis showed the presence of microscopic crystalline particles with Cr, P, and O as the major elements. Further characterization of the chromium precipitates using XRD and Raman successfully identified the product as chromium (III) metaphosphate C-type (Cr(PO3)3, JCPDS no. 01-077-0672), in the isolated chromium precipitates.

By J. van Oldenborgh

The world market for bunkers represents some 140 MT (1980) of marine fuel oil and distillates. This is equivalent to 23CMT of coal, a potential market for steam coal larger than the total seaborne trade of steam and metallurgical coal today, and an obvious area which could contribute savings in world oil consumption. Oil bunkers are lifted fairly evenly throughout the world, the main supplying regions being Western Europe, the Middle East, North and Central America and Japan (Figure 1). Not surprisingly, the main customers are the tankers representing about 50 percent of the world market - (95 percent of the Middle East Market) - dry bulkers represent some 30 percent and general cargo ships the rest.

Jan 1, 1982

By A. J. Benham, H. Kessler

In the UK a high proportion of land-won sand and gravel is extracted from sub-alluvial gravels and river terrace gravels located within river valleys. However, extraction from deposits of this type is increasingly proving to be less acceptable. Quarries within river valleys often have a high visual impact and the cumulative impact of these operations in close proximity to each other can be high (figure 1). River valley operations are almost always restored to open water. Whilst these may be attractive for nature conservation and provide leisure activities, they can also have a serious impact on the natural hydrology of the flood plain. Wet restoration of quarries located close to airports or airfields can also lead to concerns regarding increased risk of bird strike on aircraft. The Civil Aviation Authority recently suggested that an exclusion zone of 13 km be applied around all airports and airfields to reduce the potential for bird strikes on aircraft. This action is likely to have a serious impact on the availability of potential sand and gravel extraction sites in river valleys.

Jan 1, 2005

By M. P. Saunders

A comprehensive, site specific water management plan is of primary importance to the successful implementation, operation and decommissioning of any mining project. Formulation of a plan requires an orderly planning process consisting of identifying problems, establishing planning criteria based on the guidelines and requirements of regulatory agencies, and an iterative procedure of identifying, investigating, and evaluating plan elements and alternative plans. A typical uranium surface mine operation consists of a mine pit or pits, spoil pile areas, crusher, processing plant, and tailings disposal area. A water control plan addresses the problems of diversion of natural runoff from undisturbed areas around the mine; and diversion, collection, and treatment of runoff from within the mine area. A water control plan is required to determine the location and size of appropriate control and detention structures; their cost; and the schedule for permit activity, design, and construction. The plan must be formulated to meet the requirements of both the State and Federal regulatory agencies.

Jan 1, 1981

By Michael Markels

The United States Environmental Protection Agency (EPA) is charged under the Federal Water Pollution Control Act Amendments of 1972 with establishing effluent limitations which must be achieved by point sources of discharge into the navigable water of the United States. Section 301 (b) of the Act requires the achievement by not later than July 1, 1977, of effluent limitations for point sources, other than publicly owned treatment works, which are based on the application of the best practicable control technology currently available as defined by the Administrator pursuant to Section 304(b) of the Act. Section 301(b) also requires the achievement by not later than July 1, 1983, of effluent limitations for point sources, other than publicly owned treatment works which are based on the application of the best available technology economically achievable which will result in reasonable further progress toward the national goal of eliminating the discharge of all pollutants, as determined in accordance with regulations issued by the Administrator pursuant to Section 304(b) to the Act. Section 306 of the Act requires the achievement by new sources of a Federal standard of performance providing for the control of the discharge of pollutants which reflects the greatest degree of effluent reduction which the Administrator determines to be achievable through the application of the best available demonstrated control technology, processes, operating methods, or other alternatives, including, where practicable, a standard permitting no discharge of pollutants.

Jan 1, 1975

By Nikhil Dhawan, Débora Moreira, Yogendra Pratap, Himanshu Tanvar

A glauconitic siltstone sample with a potash content of 10% is investigated as a potential potash source. The fine grain structure comprises potash bearing phases of glauconite, muscovite, and microcline. The as-received samples showed poor dissolution ~ 5%. Planetary ball milling was attempted for the dissociation of the underlying silicate structure for the potash release, and ~ 60% potash was obtained after 12-h milling. Mechanical activation (8 h, 60% NaOH) prior to heat treatment (600 °C, 30 min) was found successful in recovering more than 95%K values from glauconite. The final residue consists mainly of quartz, indicating a complete breakdown of the silicate matrix. The mechanical activation process followed is simple, adaptable, and less energyintensive compared to existing methods.

May 4, 2020

By Meghan Murphy, Yiming Sun, Kush Chohan

DTX is a 1.3-mile-long rail extension being constructed by Transbay Joint Powers Authority to extend Caltrain rail service and future California High Speed Rail service to downtown San Francisco. It includes a 3,352-foot-long mined tunnel with a cross section varying from 50 to 60 feet wide and 43 feet high to accommodate two- and three-rail tracks. DTX will be excavated in mixed-face and Franciscan Formation with ground cover ranging from 40 to 85 feet. This paper discusses how mined tunnel design has evolved since the initial preliminary design phase over 10 years ago. The current design concept for tunnel construction is also discussed.

Jun 13, 2023

By Yonghong Qin, Songbo Ma, Qi Zhang, Peng Gao, Jianwen Yu

Herein, the coal-based reduction was proposed to utilize the ferronickel slag of Jingchuan company. An excellent index with metallization rate of 99.22%, iron grade of 77.91%, and iron recovery of 92.79% was obtained at carbon addition coefficient 2.0, reduction temperature 1573 K, reduction time 60 min, the particle size of coal and ferronickel slag − 2.0 mm, and CaO content 15%. The 2FeO·SiO2 was reduced to Fe and SiO2 with the increase of temperature. The CaO could promote the reduction of iron oxide. Most of the sulfides (Fe, Cu, Co, and Ni) in the sulfonium were reduced to metal. The reduction degree increased with the reduction time and reduction temperature. The higher reduction temperature represented the higher peak value of reduction rate and the shorter time of reaching the peak value. The isothermal reduction process included three stages: early stage, middle stage, and late stage. The mechanism function were f(α) = 1/2(1 − α)3, f(α) = 3/2(1 − α)4/3[(1 − α)−1/3 − 1]− 1, and f(α) = 4(1 − α)[− ln(1 − α)]3/4, respectively. The activation energy of three stages was 183.498 kJ·mol−1, 420.077 kJ·mol−1, and 656.619 kJ·mol−1, respectively.

May 24, 2022

By Paul K. Sims

The Central City district is one of several adjacent mining areas in the Front Range, Colorado, that contain precious metal-bearing sulfide veins of Laramide (Late Cretaceous and early Tertiary) age. The districts are in the Front Range segment of the Colorado mineral belt, and are characterized by porphyritic igneous rocks of intermediate composition that have intruded Precambrian crystalline rocks in the core of the Front Range. The veins and minor stockworks that constitute the ore deposits in the district were formed largely as fracture fillings. The veins range from simple fissures to complex, branching lodes, and commonly range from less than 0.5 to about 1 m in width. The principal values are in gold and silver. The common metallic minerals are pyrite, sphalerite, chalcopyrite, tennantite, and galena; minor minerals are enargite, pitchblende, and gold tellurides. Quartz, cryptocrystalline silica, carbonates, fluorite, and barite compose the gangue. The ore deposits have a well-defined concentric zonal arrangement. A core of pyrite veins (central zone) is surrounded by a peripheral zone of galena-sphalerite vein with gold and silver. An intermediate zone contains transitional veins that have minerals characteristic of both the central and peripheral zones. The minerals were deposited in three stages during a single period of mineralization: uranium; pyrite; base metals, gold and silver. The wall rocks were altered primarily during pyrite-stage mineralization. Sericite envelopes developed adjacent to fractures, and were succeeded outward by zones of argillized rock. The valuable ore minerals were deposited in ore shoots localized by several types of structural controls, principally vein intersections, the physical nature and structure of the wall rocks, and irregularities along the fractures themselves. During supergene alteration, gold was concentrated in the upper, oxidized parts of the veins, commonly to depths of 50 m. The precious metal-bearing sulfide ore deposits are closely associated in space and time with the Laramide porphyritic igneous rocks and are believed to have been derived from hydrothermal fluids related to the magmatic activity. The ore deposits have mesothermal aspects and apparently formed in the temperature range 200°-320°C.

Jan 1, 2013

By T. Cyrul

The Polish underground mining has its long lasting tradition. High production of coal, that has recently been approaching 200 milion tons per year, put this small country among the bigest world producers of coal. To achieve such a high production, which mainly originate from very unfavourable mining and geological conditions, Polish scientists and engineers have to introduce new and original solutions to the mining practice. Many of the solutions on mining methods, ventilation, stability, subsidence etc., have had the world wide reputation, however, insufficient translations from Polish cause , that many of the recent Polish mining achievements are not known to foreign specialists.

Jan 1, 1986

By Xie Junjie, Li Shina, Ma Ruixin, Min Changli, Yin Zichen, Li Kang, Shi Zhuonan

Cesium and rubidium were effectively separated by zinc ferrocyanide coprecipitation method, and the effect of precipitant addition amount on the separation of cesium and rubidium was studied. Under the conditions of Zn/Cs molar ratio of 0.45 and Zn/Fe molar ratio of 1, the precipitation rate of cesium is 84.01% and the separation factor of Cs/Rb is 164.65. The thermogravimetric curves of the sediment were measured, and the effects of roasting temperature, roasting time, and leaching liquid/ solid ratio on the extraction of cesium were studied. Almost all of the cesium was extracted under optimal conditions: roasting temperature of 600 °C, roasting time of 3 h, leaching temperature of 25 °C, leaching time of 0.5 h, and liquid/solid ratio of 5:1 mL/g. After the leaching process, the leach liquor with high concentration of cesium of 80.17 g/L was obtained. Finally, the leach liquor was further purified by solvent extraction, and the purity of the cesium chloride product reached 99.66%.

Mar 17, 2024

By L. M. Kocher, J. R. Heberger, J. P. Pollard, M. F. Nasarwanji

Injuries associated with hands and fingers are highly prevalent in mining and identifying factors associated with these injuries are critical in developing prevention efforts. This study identifies nonfatal injury incidence rates, nature of injury, work activities, glove usage, and sources of hand and finger injuries in the U.S. mining industry, as reported to the Mine Safety and Health Administration (MSHA) from 2011–2017. Hand and finger injuries occur at a rate of 6.53 per 1,000 full-time employees, which is nearly double the rate of the next highest affected body part, the back. Most of the hand and finger injuries were classified as cuts/lacerations/punctures (53%) followed by bone fractures/chips (26%). Materials handling and maintenance/repair were common activities at the time of the incident with miscellaneous metals (pipe, wire, guards) and hand tools as the primary sources of hand and finger injury. Although information on glove use was limited, leather gloves were most often worn when an injury occurred. When worn, gloves were found to contribute to 20% of the injuries, indicating their potential to protect the hands, but also potentially put the hands at risk. Further research is necessary to determine performance requirements for gloves used in mining operations, specifically those offering cut and puncture resistance.

Mar 2, 2022