Search Documents

By H. Seguin, J. A. Le Gac, S. Bernhard, P. R. ZETTWOOG

The "Service de Protection Technique"of the "Institut de Protection et de Sûreté Nucléaire" was asked by the Commission of European Communities to conduct measurement campaigns which would make it possible to evaluate, on an experimental basis, the collective risk to miners exposed to radon in underground, non-uranium mines located in countries within the European Community. 1. METHODOLOGY USED TO CONDUCT THE CAMPAIGNS This campaign is original in that direct measurements of the individual monthly exposure to potential [a]-energy from short-lived radon daughters are made using personal [a]-dosimeters described previously (1). We call this type of dosimetry "personal dosimetry". The workers who wear the personal [a]-dosimeters were selected taking into account the various categories of workers and their work assignments in the various areas of the mine. Another way of finding out the occupational exposure of these miners consists in making numerous measurements of the radon concentration at the various work places, taking into account the time spent at each place by each worker. This procedure is too complex for an evaluation of the collective risk as requested by the Commission of European Communities and was therefore rejected. Additional data was gathered during these measurements campaigns using the following techniques (table 1). [ ] (1) Current [a]-dosimetry as practiced in France - SPT international report N° 234 - February, 1981 - P. ZETTWOOG The mines were chosen to include a larger variety of types of ore, of geological situations, and of mining methods. 2. RESULTS OF THE RADON DATA-GATHERING CAMPAIGNS 2.1 – [Uranium content of the surrounding rocks and ore] The samples taken during the campaigns make it possible to establish the U content in the rocks of the mines selected. These values, from 2 to 15 ppm, are slightly higher than those usually found (2 to 5 ppm) (table 2). [ ]

Jan 1, 1981

In the last four years, 2007~2010, 9 out of 24 metal/nonmetal underground mine fatalities were caused by ground fall across United States of America (Mine Safety & Health Administration, MSHA). To reduce or eliminate incidents/accidents caused by ground fall, this paper clarified how to design and select ground support based on different ground conditions, how to use mine ground support standards, what geotechnical engineers and underground operators should do to keep mine production free of ground failures.

Jan 1, 2012

By Edward (Ted) M. Dowey

Shaft 26B of New York City’s Third Water Tunnel was constructed by Frontier-Kemper Constructors, Inc. of Evansville, Indiana. The 176.8 m (580 ft) deep shaft will serve as the construction shaft for the Manhattan spur of Water Tunnel No. 3. Twelve m (40 ft) of over-burden was supported by a rectangular cofferdam. This shaft was excavated in 13 months, through 164.6 m (540 ft) of rock, using 24,040 kg (26.5 tons) of explosives. Concrete lining cycles included the installation of stainless steel pipes embedded in the lining as the shaft advanced. A total of 635 m (2,084 linear feet) of stainless steel pipe was installed.

Jan 1, 1997

By K. Oraee

Mining of copper ore and the related industries play an important role in Iran?s economy. Copper ore production in Iran accounts for 75% of the total production in the Middle East. All activities related to copper, that is, exploration, production, refinement etc are owned and managed by state owned companies. Decisions have been made to privatize all these activities. To assess the success of this privatization process, different components of the industry must be subject to economic analysis. In this paper, the cost estimation of all operations has been carried out. The total potential and attainable revenues have also been estimated using historical data available from the industry. Risk is a major factor in all mining activities and the copper industry of Iran has been subject to risk factors arising from many internal and external variables. These variables have been recognized and their effects evaluated. The effect of risk on the economic feasibility of the operations in the industry has also been analyzed.

Jan 1, 2011

By Satid Therdkiattikul, Donald A. Dahlstrom

By oxidizing the pyrite matrix through biological leaching of precious metals ores or concentrates, better than 90% recovery of gold and silver is achieved. The paper develops three precipitation processes that eliminates arsenic and all other toxic elements in the resulting liquor after the biological reactors. In addition, the precipitates are highly crystalline and resist resolubilization. The latter must be tested for at least six months by EPA test procedures. The three systems are temperature (must be at least 120°C or higher) lime or limestone. A continuous pilot plant was employed for all three systems and complete recommendations are given to optimize Fe/As molar ratio, reaction kinetics (detention time) pH, temperature, wt % feed solids as well as resultant reagent consumption based upon continuous operation.

Jan 1, 1995

By Jack A. McQuiston, Thomas A. Cross

Corrosion of equipment and machinery in the coal industry is usually the result of three main agents: acids, chlorides, and abrasion. Acids and chlorides are especially troublesome in coal preparation plants where soluble salts and sulfur in the coal produce a highly corrosive wash solution. Abrasion is common in all operations where coal is handled or conveyed. Together, the acid-chloride-abrasion combination results in some of the worst corrosive conditions found in any industry. The variety of equipment and structures in the coal industry calls for different corrosion control techniques. Table 1 lists the areas of concern for a number of items. Just as there is a wide variety of corrosion problems, there is a wide array of coating materials available. Tables 2 and 3 are selection charts to provide guidance in narrowing down the choices. Experience has shown that a limited number of coating systems work best on coal equipment and structures. These systems are described in Table 4. The good-better-best designation in the table refers to coating system longevity. Good indicates the least costly and shortest service life. In nearly all cases the lowest annualized cost can be achieved by using the coating system rated best, due to the avoidance of costly repaints and unnecessary downtime. The most expensive coating system, though, is worthless unless the coating system is properly applied. Field inspection to insure compliance with specifications is an important aspect, and is a service available from many coating suppliers. Even the best coating systems require periodic maintenance to achieve satisfactory results. Spot rusting from mechanical damage should be repaired annually to maximize the coatingsystem's results.

Jan 2, 1980

By M. R. Haibach, M. L. Shema, J. M. Silvis

"Since 2005, longwall coal mine operators in Pennsylvania (US) have been required to collect extensive hydrologic and biological data to document pre- and post-mining conditions of aquatic resources (streams and wetlands) overlying the subsidence control plan areas. Continued operation of the longwall mine is dependent upon empirical data demonstrating that the undermined aquatic resources have either been maintained or restored to an accepted range of pre-mining conditions. This study used quantitative hydrologic methods and comparative biological metrics to examine response of aquatic resources to longwall subsidence at the Bailey Mine located in Greene County, Pennsylvania. This study analyzed data from over 25 miles of streams and over 8 acres of wetlands that traverse the 4,779-acre study area. Hydrologic analysis of flow intermittency suggested that there are variable degrees of change to headwater streams immediately following mining; however, the majority of the effects are reversible through streamflow mitigation measures. Furthermore, the post-mining discharge from streams can be restored to within the range of pre-mining conditions the majority of the time. Biological assessments showed that greater than 95% of assessed stream length has maintained its ability to support benthic macroinvertebrate communities following mining and intervention (i.e., mitigation). Comparative metrics of the benthic macroinvertebrate communities showed that the biological community in 48 of the 50 sample sites is being maintained or restored across both high- and low-gradient streams. The effectiveness of intervention was further substantiated by the similarity in recovery times between streams having no intervention (median = 2.1 years, 95th percentile = 4.9 years) and streams with intervention, when recovery times were measured from the date of the intervention (median = 1.7 years, 95th percentile = 4.7 years). Changes to individual wetlands were observed between the pre- and post-mining assessments, but cumulatively a net gain of 7% in wetland acreage was realized. Hydrologic assessments were used to infer whether there was a potential that streams had been affected by mining; however, the ultimate test of stream recovery is based on biological metrics that establish the relative quality of the biological communities following mining. Overall, the hydrologic balance is being protected and the aquatic life use of streams is being maintained within the Bailey Mine’s subsidence control plan areas."

Jan 1, 2017

By Thomas C. Shapiro

Introduction In recent years - even months - the number of articles on computers has increased rapidly. One can hardly pick up a newspaper or magazine without seeing a computer-related article. The article usually explains how the computer will change our lives. Many of us have some concern about the nature and type of change. For most of us, though, the problem is lack of information and understanding about how computers work. In other words, how do we make cost-effective decisions about computers? This three-part series will explain, simply, what a microcomputer is, how it works, and how to decide if you need one. This first article will define terms and briefly discuss areas where computerization might be economic. The second article will discuss geology and mining applications. The third article will discuss plant, administrative, and geotechnical areas as well as the future of software development in the minerals industry. Terms and Concepts All computers have input and output devices and a central processing unit (CPU). Information - instructions and data - is communicated to the computer by means of input devices. These instructions to the computer are converted into language that the computer understands. This causes the instructions to be carried out in the CPU. The result of these operations is translated back into language that we understand. This information is then sent to output devices such as printers and video display tubes. Traditionally, peripherals were devices separate from the main-frame (the CPU and memory) and were used to input, output, and store information or instructions. Today, peripherals perform the same functions though they may be housed in the same cabinet as the CPU and memory. Historically, peripherals included all input and output devices not part of the mainframe. Input devices include keyboards, magnetic tape, and card readers. Tapes and disks are input as well as output devices. Output devices are printers, CRTs (Cathode Ray Tubes), and any mass storage device capable of storing data when directed to do so by the computer or the program. In fact, any mass storage device that can give the computer data when requested is an input device. Mass storage devices include floppy disks (thin, round sheets of plastic covered by metal particles), and hard disks. The latter are thicker and more densely coated with metal particles. This allows much more information to be stored. Another type of mass storage is magnetic tape. Its type and size varies widely. Processing and Storage Any computer understanding must include how instructions and data are processed and stored. Information is stored as a positive or a negative field known as a "bit." There are eight bits in a byte. The bits can be represented as either a one or a zero. Thus the code for a byte representing the numeral one is 00110001. The byte representing the letter A is 01000001. These codes are from the American Standard Code for Information Interchange (ASCII). ASCII defines the standard set of characters including alpha, numeric, and special characters. The computer's memory has allocated locations where instructions as well as incoming information can be stored. All information and instructions are stored as binary numbers bit by bit - zeros and ones. The amount of data that can be stored is referred to as either thousands or millions of bits or bytes. The letter "K" is used to designate one thousand units. The letter "M" is used to mean one millon units (one meg). Disks Thus, a 113-mm (5 1/4-in.) floppy disk - double sided and double density (DSDD) - contains 320,000 bytes (characters) or 320K. This is about 164 double-spaced, type-

Jan 2, 1984

By M. E. Smith

Waste rock dumps, tailings impoundments and spent leach heaps are common features at mine sites. Many of these waste disposal facilities contain sulfide-rich minerals, which generate acid mine drainage (AMD) when they oxidize. Control of AMD can be achieved by removing one or more of the three essential components in the acid-generating process (sulfides, air, or water). One AMD prevention measure is to cap the waste with an engineered cover system to minimize the infiltration of water and diffusion of air into the system. Possible cover designs include: ? Earthen ?store-and-release? covers (also known as evapotranspiration (ET) or water balance covers), including capillary barriers. These covers require climate conditions where there is both modest to little rainfall and significantly greater evapotranspiration than precipitation, both annually and seasonally. ? Low-permeability compacted clay liners (CCLs) employing fine-grained soils typically compacted at wet of optimum water content. ? Geosynthetic composite covers, comprised of a geomembrane liner placed over and in direct contact with either a CCL or a geosynthetic clay liner (GCL). These systems have been commonly used for base liners for leach pads as well as covers and base liners at municipal solid waste (MSW) landfills in the US for more than 20 years. Comparisons of these different cover systems, both in terms of performance and cost, are presented later in this paper. First, however, a review of the typical mine closure approaches, and the possible rationale behind them, is warranted.

Feb 27, 2013

Breaks in coal slurry impoundments can threaten the lives and health of area residents, destroy homes and businesses and contaminate water supplies. This dangerous potential looms over coalmining regions in West Virginia and throughout Appalachia. The Coal Impoundment Project was begun in June 2003 to provide an inventory and mapping of active and abandoned impoundments in West Virginia. The project also provides the public with specific information about the impoundments in their communities. It is dedicated to alerting residents of danger and evacuation plans, reducing risk to residents and finding alternatives to impoundments. Since its first year, more than 100 impoundment sites have been added to the project’s Website.

Jan 1, 2005

By R-H Yoon

The MicrocelTM column flotation technology has been developed based on the fundamental understanding that the first-order flotation rate constant increases approximately as the inverse cube of bubble size. In this technology, bubbles in the range of 100-400 pm are generated by pumping aerated slurry through an in-line static mixer. The high-shear agitation provided by the in-line mixer produces small air bubbles without requiring large frother additions. This column has been tested successfully for processing a variety of non-metallic minerals including kaolin clay, graphite, phosphate, and feldspar.

Jan 1, 1993

By J. C. Cawley

This National Institute for Occupational Safety and Health study was conducted to focus future research on the most significant electrical problems in the mining industry. Data from 1,926 mine electrical accidents (including 75 fatalities) that occurred between 1990 and 1999 were studied. Coal and metal-nonmetal operator- and contractor-reported data are presented. All data used in this analysis were MSHA closeout data, except 1999, which were preliminary data. Electricity was the 4th leading cause of death reported in mining despite being the 14th leading cause of injuries. Electrical shock, not electrical burns, caused 70 of the 75 electrical fatalities reported. About one-half of mine electrical accidents and fatalities occurred during electrical maintenance. Suggestions for mitigating electrical hazards are proposed.

Jan 1, 2002

By Paul A. Roy

The North Shore Connector Project for the Port Authority of Allegheny County constructs twin Tunnel Boring Machine (TBM) tunnels through cohesive soils and rock beneath the Allegheny River and a narrow city street in Pittsburgh, PA. The tunnel alignment includes an historic building on shallow foundations, modern buildings on deep foundations, and an office building constructed directly over the alignment during the design of the tunnel sections. This paper provides an overview and update of the general site conditions, TBM tunnel design, and support of excavation for the TBM launching pit. Deformation limits, ground improvement, monitoring and mitigation plans are also discussed.

Jan 1, 2008

By Daniel H. Isreal

Because the federal government owns and controls nearly 80% of the most valuable oil shale reserves in the West, it is inevitable that federal leasing and siting will play a prominent role in development of an oil shale industry during the 1980s. Also, because of recent enactment of the Synthetic Fuels Corp. authorizing up to $88 billion in loan and price guarantees-federal financing will provide the critical incentive to permit private investment in a still infant industry.

Jan 1, 1981

By S. H. Brown

In our work as health physicists*, we do a lot of public speaking and interaction with the public on issues related to development of uranium mining and milling (?uranium recovery?) in the US. Understandingly, the public has important concerns about this. Accordingly, this paper is presented in a ?question and answer? format in which we have tried to capture what are some of the most common concerns we hear from citizens and address them. We have attempted to do so based on the best scientific information we have, representing information well documented in peer-reviewed scientific literature and consensus positions from both national and international scientific standard setting bodies and related committees. We have included some of the more important of these scientifically-based references to support the information provided. Practical space limitations prevent completeness in this regard in some cases. Visit the Health Physics Society?s web site or feel free to contact me directly for additional references, information or detail ? Steve Brown. The health physicist?s primary objective is to manage the beneficial uses of ionizing radiation while protecting workers and the public from potential hazards. For more information on what a health physicist is and on the Health Physics Society, visit the Society?s web site at www.hps.org.

Feb 23, 2014

By S. G. Malghan

W.H. Moyer In reference to the section “Excess pyrite, ” the author discusses difficulties in separating chalcopyrite from pyrite. A technique does exist, and has been used commercially, for the flotation, separation, and recovery, if desired, of both chalcopyrite and pyrite. The method was described in Mining Engineering, March 1966, “An Improved Flotation Method for Cornwall Sulfides. ” While it was not used on a porphyry copper ore, it was used on a chalcopyrite - pyrite-containing ore and might well have application. Both sulfides, chalcopyrite and pyrite, were floated simultaneously using xanthate as a collector and MIBC frother to produce a cleaned sulfide product. This concentrate was then thickened and conditioned at high solids with aeration and lime to a pH above 12.0 for a period of 1.5 to 2 hr. A supplemental suppressant, such as cyanide, could be used if necessary to sharpen the subsequent separation; however, it was not required at Cornwall. The conditioned sulfides were floated with two stages of cleaning to produce a highgrade chalcopyrite froth product and a pyrite sink product barren in copper. The separation at Cornwall gave a 28.6q. Cu grade chalcopyrite product and a pyrite analyzing 0.0670 Cu. A desliming step on the raw ore initially used at Cornwall for a period of time was later discontinued. Advantages to be found in using a strong sulfide collector, such as a xanthate, is the rapid flotation it induces and, generally, an ability to float at a coarser grind. A following regrind circuit could be used to give maximum liberation and produce a clean sulfide concentration. The “differential” separation is concerned primarily with grade and with assuring a barren pyrite for maximum recovery.

Jan 11, 1986

The use of belt air in underground coal mines has been a continuous discussion since it was first introduced in the Federal Coal Mine Health and Safety Act (Coal Act) of 1969. Although the Coal Act prohibits the use of belt air to ventilate active workings, there were two exceptions prior to the 2004 Final Rule. There have been several major studies/rule-proposals by MSHA since 1985 and the most recent of which is the Technical Study Panel (TSP) established by the Mine Improvement and New Emergency Response (MINER) Act of 2006 to study the use of belt air and related issues. This paper reviews the history of belt air use, its associated controver-sies, and more specifically, the 20 recommendations unanimously approved by the TSP.

Jan 1, 2009

By C. T. Agouridis

Head-of-hollow fills or valley fills have gained national attention due to increasing environmental concerns, particularly with regards to headwater stream loss. Researchers at the University of Kentucky in conjunction with outside scientists and consultants in the fields of stream restoration, wetland restoration, and mined land reclamation have developed new design methodologies for creating a headwater stream system for a head-of-hollow fill in eastern Kentucky. The design was largely built on the Forestry Reclamation Approach (FRA), which encourages a non-compacted spoil medium to promote tree growth, in an effort to address concerns related to water quantity and quality as well as habitat development. The major components of the design included 1) modifications to the crown geometry, 2) compaction of the crown to control infiltration, 3) utilization of natural channel design techniques, 4) use of the FRA to promote tree growth, 5) creation of ephemeral channels and vernal ponds, and 6) implementation of a novel bioreactor-wetland treatment system to improve water quality.

Jan 1, 2008

By R. Dillinger

In the environmentally conscious social atmosphere today, reclamation in surface mines has become a main issue to the public and the regulatory committees. In response to this increased attention, many regulatory committees have begun to enact more stringent regulations on surface mining operations. Operations across all spectrums of the industry have seen changes. Recently and most visibly the mountain top removal mines have seen several new regulations focusing on environmental protection. Specifically regulatory committees have emphasized a focus on the methods of reclamation and recovery of layers suitable for vegetation. These layers are the most visible once the operation has concluded. Also, these layers have the most human interaction (farming, hunting, and house development). Often times the new regulations enacted are shifting from a performance base to a standards base. The key differentiator being a performance base dictates the final result while a standards base dictates the method to achieve the result. The very nature of many regulations (especially those that are standards based) not only challenges the physical limitations of the equipment used today, they come with a financial impact. For the purpose of this paper, the model will be a surface coal operation, utilizing draglines as primary overburden movers. The coal seam is ten feet thick, the overburden ninety five feet thick, the pits are 150 feet wide, and the dragline is a Bucyrus Erie 1570.

Jan 1, 2011

By K. Norrena

Grade control in open pit mining requires the specification of dig limits that account for mineral grades, economic costs, and selectivity of mining equipment. Visual identification of ore rock types is ideal, but this is not always possible in lower grade disseminated deposits where ore/waste contacts are not visually discernible. In this case, conventional grade control practice consists of a two-step procedure (1) create a map of mineral grades at some selective mining unit scale, and (2) determine practical ore-waste boundaries or dig limits on the basis of the gridded block grades or assay information. This procedure is laborious, depends on a subjective assessment of where the boundary should be, and may be economically sub-optimal. We pose the determination of dig limits as an optimization problem and solve that problem with the technique of simulated annealing. Simulated annealing has the unique advantage of being able to combine multiple non-linear constraints into a single objective function. We use maximum profitability and the ability of the equipment to mine the proposed dig limits as constraints in the determination of optimal dig limits. We require a map of expected profit for eah block. Geostatistical techniques are recommended, for mapping expected profit but not necessary. Geostatistics will provide a quantification of the uncertainty in the grades within rock types using all available blasthole samples and exploration drilling. Some variant of L-optimal estimation or kriging can be used to determine the block-by-block classification that is economically optimum. We also need the expected profit for each block. It is unrealistic to assume free selection, that is, each block cannot be extracted independently of its neighbors. The optimal balance of ''accepting dilution'' and ''wasting ore'' is achieved to maximize profit subject to equipment constraints.

Jan 1, 2001