Search Documents

By S. H. Seyedein, Hamed Tavakkoli, Mohammad Reza Aboutalebi, S. N. Asharafizadeh

The liquid–liquid extraction behavior of lutetium from different acidic solutions was investigated using two extractants, D2EHPA and PC88A, in kerosene. Lutetium extraction reactions with D2EHPA and PC88A from HNO3 and H2SO4 solutions were chemically and thermodynamically analyzed. It was found that each Lu cation was complexed with six monomers of the organic extractant and released three protons. Simultaneously, the Lu cation was instituted in the P–O–H group of the extractants. Thermodynamic analysis of reactions between extractants and acidic solutions showed that the D2EHPA-HNO3 system is the most favorable for extracting lutetium. It is noted that the calculated equilibrium constant of the reaction in this system was approximately six times larger than that of the D2EHPA-H2SO4 system. However, the value of the equilibrium constant for the D2EHPA-HNO3 system was evaluated to be approximately 200 times greater than that of the PC88A-HNO3 system. Therefore, one can conclude that the extraction behavior of lutetium is more influenced by the extractant type than the solutionmedium. The synergistic effect of different mixtures of extractants on the solvent extraction of lutetium was also examined, and the highest synergistic factor was obtained for a binary mixture of PC88A:D2EHPA at the ratio of 4:1 for both aqueous solutions.

Mar 15, 2021

By Gamal Rashed, Zorica Radakovic-Guzina, Khaled Mohamed

"Underground coal mines use mechanical bolts in addition to other types of bolts to control the rib deformation and to stabilize the yielded coal ribs. Limited research has been conducted to understand the performance of the mechanical bolts in coal ribs. Researchers from the National Institute for Occupational Safety and Health (NIOSH) conducted this work to understand the loading characteristics of mechanical bolts (stiffness and capacity) installed in coal ribs at five underground coal mines. Standard pull-out tests were performed in this study to define the loading characteristics of mechanical rib bolts. Different installation torques were applied to the tested bolts based on the strength of the coal seam. A typical tri-linear load-deformation response for mechanical bolts was obtained from these tests. It was found that the anchorage capacity depends mainly on the coal strength. Guidelines for modeling mechanical bolts have been developed using the tri-linear load-deformation response. The outcome of this research provides essential data for rib support design.INTRODUCTIONThe design of rib bolting in U.S. coal mines is based on a trial-and-error process, which is insufficient to eliminate injuries and fatalities caused by rib falls. In the last 10 years, rib failures have resulted in 17 fatalities, representing 52% of the ground-fall fatalities in underground coal mines in the United States (MSHA, 2018). Recently, NIOSH researchers surveyed 90 sites in 14 underground coal mines in the Eastern United States and found that 11 mines are bolting coal ribs, with 4 of those mines using the conventional mechanical bolts and the others using fully-grouted bolts. NIOSH researchers are developing an engineering design procedure for rib support. Pull-out test programs for mechanical and grouted rib bolts were conducted to understand the rib control mechanisms of rib bolts. Only the test results of mechanical bolts are presented in this paper.Mechanical bolt (or point-anchored bolt) is a tensioned bolt anchored down the borehole with a mechanical expansion shell or a resin-grouted medium (Peng and Tang, 1984). The mechanical anchor bolt consists of a plug, a shell anchor, a headed bar with the top end threaded, a bearing plate, a hardened washer, and occasionally a friction-reducing washer. The shell anchor can be either standard or bail type (Figure 1). The standard type shell is held in place by a nut, while the bail anchor uses a strap to hold the shell in place (Peng, 2008). The diameter of the bar is generally 16 mm (? in) for the #5 bolt or 19 mm (6/8 in) for the #6 bolt. The diameter of the hole that the bolt is inserted into must be carefully controlled, since an oversized hole can result in poor anchorage (Moss, 1971). The anchorage is obtained by applying torque to the bolt head, which in turn pulls the plug down in the shell and expands the serrated leaves against the sides of the hole-wall. In the resin-grouted anchor, the resin replaces the mechanical expansion shell at the end of the hole. The anchorage is achieved by bonding between the resin, bolt, and the hole-wall."

Jan 1, 2019

By M. Shriwas, F. Calizaya

"Recirculation is prohibited in many coal mining countries because of the fear that the re-use of return air would allow the build-up of air contaminants at the workings. The incorrect design and location of a booster fan in any ventilation network can create unsafe condition due to recirculation. The current approach to investigating recirculation using simulation software requires manual effort which becomes tedious in a complex and a large network. An algorithm-based C++ program was designed to detect the recirculation in a booster fan ventilation networks. This program needed an input file prepared from output file generated by any ventilation simulator. This program created an output file for recirculation. This program demonstrated the strong capability to detect the recirculation in a sample network and a coal mine ventilation network. The outcomes of this program were documented in this paper. INTRODUCTION The proper design and location of booster fans eliminate the safety hazards associated with high main fan pressure. Conversely, the incorrect design of booster fans in any ventilation network can create unsafe conditions due to uncontrolled recirculation. The proper utilization of a booster fan derives benefits to reduce the main fan pressure, leakage, and consequently ventilation cost especially with high resistance network due to deep and extensive working area in a mine. However installation of booster fan may create uncontrolled recirculation, if it is not sized and located properly with respect to main fan. Recirculation is prohibited in many coal mining countries because of the fear that the reuse of return air would allow the build-up of air contaminants at the workings. Therefore, it is imperative to check the recirculation while designing and operating booster fan for a ventilation network. This paper deals with an algorithm based C++ program to detect the recirculation in a booster fan ventilation networks. This program was implemented to detect the recirculation in a sample network and a coal mine network. STATEMENT OF PROBLEM The currently available ventilation simulation programs do not give much information about recirculation for the generated solution (fan pressures). The current approach to investigating recirculation using simulation software requires manual effort, i.e., traversing from node to node in the output network by the simulator while keeping tracks of all the nodes that form recirculation paths. This is an easy task in a simple ventilation network, but it becomes tedious and sometimes very confusing in a complex and large network. Moreover, the presence of multiple recirculation paths makes the manual effort more complex and difficult, especially in separating multiple loops that are connected together. Thus, there is a need for a more efficient program that will detect and quantify the recirculation efficiently, for the generated fan pressures. A program is developed to detect the recirculation(s) in a network."

Jan 1, 2015

By Carlos A. Jaramillo, Seng Hing Ngu

"The Murum Hydroelectric Project is a 944-MW development consisting of a 145 meter high RCC dam, two 2660 meter long, 9 meter excavated diameter upper pressure tunnels, surge shafts, two 950 meter long 7 even meter OD penstock tunnels and a surface powerhouse. The project is located in the eastern section of the State of Sarawak, Malaysia, about 200 kilometer from Bintulu, in the Rajang Fold-Thrust Belt, an Upper Cretaceous to Upper Eocene fold and thrust belt that extends under most of Sarawak. The Belaga Formation consists of a thick sequence of deep marine sediments currently appearing as steeply dipping strata of thin to thick bedded, fine to medium grained sandstone interbedded with argillaceous rocks, resulting on a “Flysch” type geologic environment. The project pressure tunnels were excavated perpendicularly to these strata resulting on frequent change on rock conditions and behavior, and required rock support. This paper describes the characterization of the rock mass, design of rock support, and incidents during construction. Particularly interesting were convergence issues in Tunnel 1 resulting from Tunnel 2 excavation. INTRODUCTION The Murum Hydroelectric Project is located in the eastern section of the State of Sarawak, Malaysia, about 200 kilometers from Bintulu, and upstream of the Bakun Hydroelectric Project. The project consists of a 145 meter high RCC dam, a 50 meter high intake tower, two nine meter OD and 2660 meter long upper pressure tunnels, two nine meter OD and 175 meter long vertical shafts, two 25 meter diameter and 80 meter deep surge tanks, two seven meter OD and 950 meter long penstock tunnels and four seven meter OD and 50 meter long branch tunnels, two 8 meter diameter to 3.4 meter diameter and 1400 meter long penstocks installed within the shafts, penstock tunnels and branch tunnels ending in a powerhouse with 944 MW installed capacity. LAYOUT OF THE WATERWAY TUNNELS The two waterways tunnels are basically parallel as shown in Figure 1, with each tunnel supplying water to two units in the powerhouse. The tunnels start separated 25 meters center to center, but 250 meter from the intake the separation increases to 35 meters. The tunnels are lined with reinforced concrete until they reach the surge shafts and steel lined from there to the powerhouse. The tunnel profile is shown in Figure 2."

Jan 1, 2016

By W. R. Reed, J. P. Rider

"The National Institute for Occupational Safety and Health (NIOSH) Office of Mine Safety and Health Research (OMSHR) has recently developed a series of models utilizing computational fluid dynamics (CFD) to study airflows and respirable dust distribution associated with a medium-sized surface blasthole drill shroud with a dry dust collector system. CFD models were constructed in ANSYS FLUENT Version 15. Previously run experiments conducted in the NIOSH full-scale drill shroud laboratory were utilized to validate the models. The setup values in CFD models were calculated using experimental data obtained from the drill shroud laboratory and measurements of test material particle size. Subsequent simulation results were compared with the experimental data for test scenarios, including 0.14 m3/s (300 cfm) bailing airflow with 2:1, 3:1, and 4:1 dust collector-to-bailing airflow ratios and 0.24 m3/s (500 cfm) bailing airflow cases with 2:1, 3:1 and 4:1 dust collector-to-bailing airflow ratios. For the 2:1 and 3:1 ratios, results showed the calculated dust concentrations from the CFD models were within the 95% confidence intervals of the lab experimental dust concentrations. This paper describes the methodology used to develop the CFD models, to calculate the model dust input, and to validate the models based on experimental data. Problem regions were identified and revealed by the simulation of a dry dust collector system. The simulation results could be used for future development of dust control methods for a surface mine blasthole drill shroud. INTRODUCTION In surface mines, production drilling is an essential process in blasting which fractures the hard rock overburden for removal. Holes with a predetermined pattern, diameter, and depth are drilled into the overburden to introduce explosives. During the drilling process, considerable amounts of respirable dust are produced. Past research conducting area sampling at blasthole drills has documented time-weighted average respirable dust concentrations ranging from 8.68 to 95.15 mg/m3 [1] and 1.04 to 52.30 mg/m3 [2]. These high dust concentrations, which may contain silica, can lead to respirable dust over-exposures for the drill operator, drill helper, and other personnel in the vicinity. These over-exposures can lead to silicosis, an occupational lung disease that has no cure and is ultimately fatal. In order to prevent the development of silicosis to mine workers, the Mine Safety and Health Administration (MSHA) regulates the exposure to respirable dust. For metal/nonmetal (M/NM) mines, MSHA has adopted the threshold limit values recommended in 1973 by the American Conference of Governmental Industrial Hygienists (ACGIH) [3]. The total airborne dust standard is 10 mg/m3. However, if the sample contains greater than 1 percent quartz (the most common form of crystalline silica), a respirable dust standard is calculated with the following equation: Respirable dust standard = (10 mg/m3) / (% respirable quartz + 2)"

Jan 1, 2016

By Thomas A. Morley

This paper deals with the minimization of ventilation costs for the controlled-flow mine ventilation network. Cost elements considered include the cost of power and the fixed cost of the fans. The problem is modeled in a mixed-integer programming format and solved via the branch and bound method. Computational experience with sample problems is discussed.

Jan 1, 1983

By K. Hajmrle

The production of nickel coated mica composite powder by hydrogen reduction of a nickel ammine sulphate solution, followed by the production of molded plastic samples containing Ni/Mica is described. Sample preparation by injection or compression molding is outlined and the better results in compression molding are explained by the combination of better particle-to-particle contact, less particle breakage during processing, and more random particle distribution in the plastic. Three volume resistivity measurement techniques are described and compared. Two of them (conductive paint and silver-rubber electrodes) are found reliable and are used throughout the work. The influence of nickel content and particle size of Ni/Mica on volume resistivity is evaluated and the optimum product defined. One of the most important assets of Ni/Mica, its ease of injection molding, is demonstrated by the good electrical properties obtained with little optimization of the injection molding process. Surface roughness of molded plastics with and without Ni/Mica is briefly discussed. Shielding effectiveness of Ni/Mica in four plastics (PP, ABS, PBT and PC) is presented and correlated to volume resistivity data for the same materials. The addition of 15 to 50 weight % Ni/Mica (3 to 16 volume %) to plastics and subsequent injection or compression molding produces composite materials having low volume resistivities (0.03 to 1 ohm.cm) and high shielding effectiveness (40 to 70 dB).

Jan 1, 1988

By Jonathan G. Price

The 2011 report titled ?Energy Critical Elements: Securing Materials for Emerging Technologies? by the American Physical Society?s Panel on Public Affairs and the Materials Research Society surveys potential constraints on the availability of these elements and identifies five specific areas of potential action by the United States to ensure their availability: 1) federal agency coordination; 2) information collection, analysis and dissemination; 3) research, development and workforce enhancement; 4) efficient use of materials and 5) market interventions. Energy-critical elements (ECEs) are a class of chemical elements that currently are critical to one or more new energy-related technologies. A shortage of these elements would significantly inhibit large-scale deployment, which could otherwise be capable of transforming the way in which energy is produced, transmitted, stored or conserved. The report addresses elements that have not been widely extracted, traded or used in the past, and therefore are not the focus of well-established and relatively stable markets (such as carbon in coal or uranium as fuels, copper, aluminum, nickel and iron, all of which are clearly vital in energy applications).

Jan 1, 2011

By MYRIAM FRANCOEUR, JOHN R.R. BOWLING, ADAM MCFADDEN

As duct-fan systems push the envelope of power, length and cost, their design calls for a more comprehensive technoeconomic analysis to ensure they deliver the expected results without failure and cost overrun. This work explores the numerous factors to include in the design of an extensive (semi-)rigid duct-fan system. Besides delivering a given airflow, the system must satisfy component limitations and power constraints during its lifetime. We evaluate the assumptions underlying the positioning of in-line booster fans in a long gapless duct-fan system and propose a strategy for specifying the location and blade pitch of successive booster fans to prevent system failure due to a partial vacuum.

Oct 1, 2022

By AJIT SWAIN, SUNATI MOHANTY

The ability to predict the dewatering performance of an industrial hydrocyclone from a laboratory-model hydrocyclone is of great importance. In this study, laboratory-scale hydrocyclone experiments were conducted using silica sand samples at 10 percent solid concentration for dewatering with Mozley hydrocyclones with diameters of 2 in. and 4 in. The objective is to predict the design parameters for an industrial dewatering cyclone to achieve higher solid concentration in the underflow. A model was developed based on the Nageswararao hydrocyclone model with the help of a commercial simulator for a hydrocyclone operating at 100 t/h and 20 percent solid concentration to achieve 80 percent solid recovery at 45 percent solid concentration in the underflow.

Mar 1, 2023

By Christopher Mark

Sixty years ago, underground coal mining was the most hazardous job in the United States. Roof falls killed about 100 miners every year, more than all other causes put together. Fast forward half a century to 2016, and the first year ever with zero roof fall fatalities. Just three miners were killed by roof falls during the following six years. To understand how this historic goal was achieved, this study analyzed hundreds of roof fall fatality reports covering five decades. It found that the immediate effect of the Federal Coal Mine Health and Safety Act of 1969 (Coal Act) was to reduce the riskiest activities, like needlessly going under unsupported roof. Other hazards, like large roof falls, required technological developments before they were brought under control. Roof control plans, which the U.S. Bureau of Mines had been advocating since the 1920s, fostered the necessary improvements in both the safety culture and the mining technology.

Jun 1, 2024

By Mokhinabonu Mardonova, Yosoon Choi

Open-source technology to support Industry 4.0 has become the target of academic research in many sectors. This study reviews the trends of open-source technology, its forms, and some industrial applications. As a case study of the use of open-source hardware and software in the mining industry, this study proposed a low-cost environmental monitoring system for nonmetallic underground mines to support mine safety and occupational health. The system was developed using open-source hardware, Arduino and 3D printer, to design the monitoring device, and open-source software, MIT App Inventor, to develop an Android application for smartphones to enable remote communication with the system. Field experiments were conducted at an underground tunnel and a nonmetallic underground mining site to assess the performance of the system in mobile and static modes, respectively. Although a few limitations related to the precision of the low-cost dust and gas sensors exist, the findings of the experiments show that the mining industry can benefit from open-source technology deployment when considering cost factors.

By Joseph Clare

It’s not the 1960s anymore. Upgrading wastewater pipelines in the current era demands the latest trenchless technology to minimize impacts. King County Wastewater Treatment Division in Seattle, Washington is designing a nearly mile long Direct Pipe® influent sewer combined with microtunneling to replace a 1960s era trunk sewer constructed along and within Coal Creek and its natural area. Trenchless installation using Direct Pipe® and microtunneling was chosen due to reduce impacts to residential neighborhoods, natural creek environments, and the constraints of topography

Jun 13, 2021

By Kanaya Koichiro

Doyashiki Concentrator in Hanaoka mine of Dowa Mining Co., Ltd. started the operation in 1943, treating the ore mainly from Doyashiki ore deposits. After the cessation of mining of Doyashiki ore body in 1973, Doyashiki concentrator began to treat the ore from Fukazawa mine instead in the same year, and furthermore the ore from Ezuri mine In 1979. Currently Doyashiki concentrator treats 30,000 tons of ore per month from both mines. The ore treated is complex sulfide ore, called "Kuroko" (black ore), and the principal minerals contained in the ore are chalcopyrite, galena, sphalerite, pyrite, and barite, accompanied by bornite, tetrahedrite, tennantite, covellite, stromeyerite, argentite, polybasite, pearcite, and electrum. The Principal gangue minerals are quartz, gypsum and clay. The grade of the feed to the concentrator averages 0.9 p/t Au, 110 g/t Ag, 1.1 %Cu, 2.8 %Pb, 9.2 %Zn, 5.0 % Pyrite-S and 13% BaS04. The feed is, after washing and two-stage crushing, ground to 88% minus 200 mesh in a rod mill and ball mills with cyclone classifiers, and five concentrates are recovered by flotation. Primarily copper-lead bulk concentrate is recovered by sulfurous acid-lime flotation method, and then from the bulk concentrate copper concentrate is floated by hot pulp flotation method, sinks being lead concentrate. Zinc concentrate is recovered from the tailing of copper-lead bulk flotation, pyrite concentrate from zinc flotation tailing and barite concentrate from pyrite flotation tailing. The final tailing is sent to the dam.

Jan 1, 1982

By S. K. Kawatra

In many mining operations, particularly northern open-pit mines, large seasonal variations in grinding slurry temperature can occur. It is shown in this paper that this temperature shift can cause a winter-time loss in autogenous grinding efficiency of as much as 20Y. if it is not controlled. Laboratory experimentation indicates that much of this effect is due to increases in slurry viscosity as the temperature is decreased. An additional effect may result from changes in rock strength upon freezing, for which possible mechanisms are discussed. However, no effect clearly resulting from rock strength changes has been definitely confirmed.

Jan 1, 1990

By Donald R. East

For many years there has been increasing pressure on mining companies, not without some justification, to design tailings storage facilities which guarantee some degree of protection against process solutions entering local groundwater and surface water flows. A fairly straightforward approach to achieving this has been to design conventional water-retaining type structures, and this has often been reinforced by the need to store large volumes of process water and seasonal run-off within the tailings facility. The conventional design uses naturally occurring geological barriers and a conventional embankment with possibly a grout curtain, or artificial barriers around the entire facility, using either imported low permeability soils, admixtures, or synthetic liners. While these approaches may achieve the primary objective of minimizing seepage, various other factors should be considered. Firstly, by depositing the tailings slurry in a sub-aqueous manner, the tailings, especially if relatively fine grained, will settle to very low densities and little or no on-going consolidation may occur over the operating life of the mine, There have been many cases where measured pore pressures within the tailings mass equal the total overburden stress, i.e., no consolidation and no strength, many years after decommissioning.

Jan 1, 1998

By P. D. Rao

The combination of high moisture and low heating value has restricted most low-rank coal (LRC) usage worldwide to mine-mouth power generation. Coals from Usibelli Coal Mine and the Beluga coal field have a heating value of approximately 8,000 Btu/lb and 28% moisture. Hydrothermal treatment (at 275 to 352'C) of lump coal from Usibelli Coal Mine and Beluga coal field enhanced the heating value of the coal, on an equilibrium moisture basis, from 8,000 Btu/lb to nearly 12,000 Btu/lb. The product coal with high heating value and 0.2 % S is an environmentally acceptable premium fuel. The Hardgrove grindability index of the coal is greatly improved, further enhancing its value. Increase in hydrothermal drying temperature promotes vesiculation of resinite. Vitrinite reflectance increased to 0.72 and vitrinite was subjected to widespread visiculation resulting in a coke like structure indicative that the material went through the fluid stage.

Jan 1, 1991

By V. K. Srivastava, T. Gupta, T. Ghosh

"In recent years, the demand for rare earth elements (REEs) has grown due to increasing demand and global supply shortage. The supply deficit of these critical elements has encouraged the search for new sources, with coal and coal byproducts as possibilities. Coals from certain parts of the world can be rich in REEs and can approach a total concentration of 1,000 ppm. Two Alaskan coal samples, from Healy and Wishbone Hill, were investigated for the effects of density and particle size on REE concentrations for three selected size fractions, and flotation tests were conducted on finer fractions. Additionally, bottom ash and fly ash samples from a power plant were examined for their REE concentrations. The results show that the upgrade potential for REEs on an ash basis from a whole-coal basis ranges from 2:1 for the Wishbone Hill samples to 4:1 for the Healy coal samples. Flotations of the finer fractions of the two coal samples, conducted under similar conditions, revealed higher concentrations of REEs in the tailings. Both coal samples had comparatively higher contents of light-group rare earth elements (LREEs) than heavy-group rare earth elements (HREEs). REE content trends for the power-plant products on an ash basis indicate that fly ash has slightly higher concentrations of both LREEs and HREEs than bottom ash. IntroductionRare earth elements (REEs), also known as rare earth metals, and their compounds are vital components in industrial, automotive, petrochemical, defense and medical applications. Dysprosium in combination with other elements is used in laser materials and nuclear control applications. Neodymium is present in magnets that are used in the manufacture of wind turbines and hybrid cars. Europium, terbium and yttrium are used in devices that have visual displays such as computer screens and laptops (Haxel, Hedrick and Greta, 2002; Bunzli, 2013). REEs pose fewer environmental problems of disposal and recycling than their conventional heavy metal counterparts (Haxel, Hedrick and Greta, 2002). They are key materials for radar systems, avionics, modern national defense and satellites (Cammarata and Sieradzki, 1994; Hedrick, 2010; Martin, 2010; Szumigala and Werdon, 2011; Cordier, 2011; Bunzli, 2013). REEs are often classified into light-group rare earth elements (LREEs) and heavy-group rare earth elements (HREEs). This classification is primarily based on the electronic configuration in the outermost shell. LREEs, ranging from lanthanum to gadolinium, have a single or no spinning electron in the outermost 4f shell while HREEs, ranging from terbium to lutetium, have paired electrons in the 4f shell. This difference in electronic configuration is responsible for the differences in physical and chemical properties of REEs."

Jan 1, 2017

By George B. Rice

In a recent speech in Pittsburgh, Dr. George Keyworth, the President's Science Advisor, made a statement which I believe deserves our very careful consideration. Dr. Keyworth said that there is no energy crisis. The crisis, he explained, is simply that people refuse to accept the solution. The solution which Dr. Keyworth has in mind is increased utilization of our abundant supplies of solid fuels and, in particular, uranium. I share his view concerning the solution to our energy needs. The use of uranium fuel is a safe, clean, and dependable means to generate our electric power. It is time that we addressed the real energy crisis: the refusal to accept the nuclear solution. The reason for the refusal is not difficult to find. It is nihilistic thinking about risk. Under this thinking, we assume the worst possible case and act accordingly, simply because we cannot prove to a total certainty that nuclear energy is perfectly safe. If this absolutist approach were generally applied throughout our society, there is no doubt all of us would soon be sitting around our campfires fearfully holding the wild animals at bay with our trusty spears. Today I am here to enlist your support in reversing the regulatory trend that threatens the very extistence of the nuclear power industry. As distinguished scientists, engineers and businessmen, you can use your influence to help bring rational regulation to the industry. Our industry supports strong safety and environmental protection programs. We understand the need for and do not object to reasonable regulation. Many anti-pollution measures can be practical to implement, cost effective and highly successful in minimizing environmental impacts. However, it is a fact of life that in the field of health and safety regulation, the law of diminishing returns operates with a vengeance. Absolute or near-absolute safety is impossible and any attempt to achieve it is intolerably costly. Fixation on absolute safety is particularly acute in the regulation of the nuclear power industry. Government Agencies, overly anxious to allay the irrational fears of those opposed to nuclear power, are literally regulating the industry to death - exactly the result sought by the anti-nuclear groups. Dr. Robert L. DuPont wrote in a recent issue of [Business Week]: "The nuclear power industry has been virtually stopped in the U.S. [because of fear]. This is true despite the fact that for more than 20 years the commercial nuclear industry has operated under unprecedented public health scrutiny and that to date there have been no radiation-related injuries, let alone deaths, suffered by any member of the public."1 I believe a useful way to convey the nature of the problem faced by the nuclear industry is to review an example of [unreasonable] regulation. While the example relates to our domestic industry, I am certain there are similar situations in other countries. For the example I will use the Nuclear Regulatory Commission's recently issued regulations governing the stabilization of uranium mill tailings.2 These regulations, known as the Uranium Mill Licensing Requirements, specify, among other things, that radon emanation from uranium mill tailings be limited to no more than 2 pCi/m2-sec. First, one must understand that this standard will have virtually no impact on the total amount of radon to which the public is exposed. Radon emitted from even completely unstabilized tailings piles is a tiny fraction--much less than 1%--of the amount of radon released from natural soils in the United States.3 In fact, it is far outweighed by natural variations in the background flux. For example, changes in the level of the Great Salt Lake in recent years have had [eight times] as much effect on the amount of radon released into the Salt Lake City regional air than the annual release from the Vitro Mill tailings pile located in that city.4 Nevertheless, NRC claims that the standard is required to protect the public. The Commission admits, however, that there are no studies which establish that exposure to radon at the low levels associated with uranium mill tailings will result in any adverse health effects.5 In the absence of actual evidence, the Commission assumes that some such effects will occur on the basis of the linear, non-threshold model.6 Employing this model, NRC calculates that the maximum hypothetical risk for the average member of the population is only about 1 in 70,000,000 from the radon that would be emitted from [three times] the number of mills now in existence, even if the tailings produced through the year 2000 are left unstabilized.7 NRC has elsewhere explained that this level of risk would be equivalent to the risk posed by "a few puffs on a cigarette, a few sips of wine, driving the family car about 6 blocks, flying about 2 miles, canoeing for 3 seconds, or being a man age 60 for 11 seconds." This level of risk is [de minimis] in comparison to other risks commonly and readily incurred in our society.9 Moreover, even this remote risk is overstated. A group of prominent health physicists, including experts from the Department of Energy, The Environmental Protection Agency, Britain, Canada and Germany recently published a study indicating that the risk to the public per unit exposure to radon can be no greater than one-third that suggested by the Commission, and [may in fact be zero].l0 Regulators routinely rationalize the need for their regulations. For example, NRC attempts to justify the radon flux standard because it is necessary to reduce the risk to someone who builds a house on top of a tailings pile. This possibility, however, is totally unrealistic because the Mill Tailings Act requires that stabilized tailings be transferred to

Jan 1, 1981

Flooded-bed scrubbers on continuous miners have been shown to be an effective respirable dust control technology, traditionally used during the extraction of extended cuts of up to 12.2 m (40 ft). To effectively use scrubbers in faces that employ exhaust ventilation, the return ventilation curtain or tubing should be located outby the scrubber discharge on the continuous miner, which results in a setback distance from the face of approximately 12.2 m (40 ft). The goal of this research was to compare respirable dust levels generated in 6.1 m (20 ft) cuts when using extended curtain setbacks with a scrubber operating to dust levels in 6.1 m (20 ft) cuts when using traditional exhaust face ventilation without a scrubber operating. Dust surveys were completed at three mines with area and personal sampling conducted to quantify respirable dust concentrations on a cut-by-cut basis. Sampling results did not show a statistically significant difference in respirable dust at the continuous miner or shuttle car locations with and without the scrubber operating. However, with the scrubber operating, respirable dust concentrations in the return airstream downwind of the miner showed reductions of 91%, 86%, and 40% at Mines A, B, and C, respectively. The reductions at Mines A and B were statistically significant. Likewise, reductions in respirable quartz dust levels in the miner return were observed at all three mines, with statistically significant reductions of over 80% observed at Mines A and B. Consequently, operation of the flooded-bed scrubber did not impact respirable dust levels in the face area but did significantly reduce respirable and quartz dust levels downwind of the continuous miner. These results were obtained with the mines operating at or above the minimum operating levels specified in their ventilation plans.

Feb 23, 2014