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By H. H. Kleizen

The operation range and efficiency of dewatering apparatus are important factors in the selection of an apparatus for a given purpose. In this paper theories are presented allowing to predict these basic characteristics for different dewatering apparatus and compared with experimental and practical data obtained on coal and ore slurries.

Jan 1, 1989

By K. Deaton

"INTRODUCTION A packaged cooling system is being developed for refuge alternatives (RAs) that meets MSHA qualification guidelines for deployment in coal mines. This system will allow full occupancy ratings of deployed Refuge Alternatives (RAs) to be maintained by keeping the apparent temperature inside the RA from exceeding 95°F. Research investigations sponsored by NIOSH have shown that heat buildup caused by occupants in mobile RAs will result in apparent temperatures that exceed the 95°F limit established in 30 CFR 7.504. Figure 1 shows the temperature rise in an inflatable RA having an occupancy rating of 23 people at an 81°F mine air temperature. This plot shows the need for either heat mitigation or occupancy derating in warmer mines. The RAECS will be designed to provide enough heat mitigation to eliminate occupancy derating due to heat buildup over the 96 hour refuge period.This paper describes testing of a prototype cooling system that uses proven vapor compression technology powered by batteries to keep the RA interior below the 95° limit for a minimum of 96 hours. Testing of this prototype cooling system was conducted in December of 2015 and January of 2016 at the NIOSH test mine in Bruceton, PA. December testing was conducted at the prevailing mine ambient temperature – approximately 60°F. The January testing was done with the mine ambient temperature in the immediate vicinity of the RA artificially elevated to 85°F. Realistic heat gain from RA occupants was provided by human simulators developed by NIOSH. These simulators add sensible heat corresponding to human metabolic processes and latent heat generated by respiration and perspiration. Heat generated by CO2 scrubbers was also added. Results of cooling system performance using these simulated loads at the two ambient conditions are described. A comparison of the apparent temperature in the RA using two different control techniques is also presented. This work documents the ability of the cooling system to meet the established apparent temperature limit at the full occupancy rating of a six person RA. A new cooling system intended for use with existing RA deployments and having greater cooling capacity is currently in development and will be described."

Jan 1, 2017

By L. B. Bramlett

The Archean (2.65 b.y.) aged Canning Stock at Copper Mountain, Wyoming contains an average of 20 ppm U. The North Canning and Fuller deposits occur within the enriched interior of the stock. Post-Laramide development of super gene enrichment blankets occurred in wide (25- 100 m) crushed zones. Hematite and chlorite accompany pyrite and sooty pitchblende in the mineralized zones. Reduction mechanisms proposed for deposition of pitchblende are: 1) sulfides, 2) hydrocarbons, 3) bacteria, 4) the water table, or 5) some combination of these. Abundant tar- type organics appear to have preserved the enrichment blankets from degradation. Trace element and radiometric data define target zones, but exploration models focus on favorable structure.

Jan 1, 1980

By Wenming Wang, Edgar E. Vidal, Scott A. Shuey, Patrick R. Taylor, Judith C. Gomez

Introduction In modern society, vanadium is defined as a strategic metal. Some 90% of the global consumption is used as an alloying agent for carbon steels, tool steels, and high-strength low-alloy steels (particularly for pipelines). Advanced titanium-aluminum-vanadium alloys are seeing application in the aerospace industry. Small but ever growing amounts are finding application as catalysts or in electronics. New uses are continually being discovered for this metal. One example of a new application is the vanadium-redox battery for use in generation plants and back-up power sources. Vanadium is found in a large number of minerals, of which the most important are carnotite, roscoelite, vanadinite, mottramite, and patronite. Just over a third of the world's vanadium is produced as a primary product; the balance is a by-product of the iron and steel, oil refining, power generation and uranium enrichment industries. Vanadium can also be sourced by recycling spent catalysts from the petrochemical industry and ash produced by the combustion of oil emulsion in power stations. However, recycling activities are believed to account for only a small amount of total world supply. Vanadium is recovered from these ores largely as the pentoxide (V2O5) [1]. The major sources of vanadium-bearing magnetite ores are scattered throughout Australia, China, Russia, and South Africa. Current estimates of world’s Proven & Probable vanadium reserves are of the order of 41.3 million tones [2, 3]. Commercial vanadium-bearing titaniferous magnetite deposits can be found in Kachkanar, Russia; Pan Zhihua, China; Bushveld, South Africa; and Windimurra, Western Australia [4]. Other deposits have been found in New Zealand, Canada, and India, among other countries. Vanadium consumption in the steel sector has increased some 7% per ton of steel over the last 10 years as new alloying applications have been found to improve steel's strength-to-weight ratio. Future demand from the aerospace and nuclear industries for non-ferrous vanadium alloys such as titanium and super-alloys is also likely to grow. Vanadium is usually added in the form of ferrovanadium, a vanadium-iron alloy. Vanadium compounds, especially the pentoxide form, are used in the ceramics, glass, and dye industries, and are also important as catalysts in the chemical industry. While established approaches may be used at an industrial scale to treat vanadium-bearing titaniferous magnetite ores in several countries, new alternatives are being developed worldwide. This review will give short overview of the treatment of vanadium-bearing titaniferous magnetite ores, an overview of direct reduction and direct smelting processes and an approach to determine technical alternatives for the property.

Jan 1, 2005

By P. D. Chamberlain, R. M. Nadkarni, D. J. Kinneberg

Introduction The relationship between precious metal miners and gold refiners has been uneasy over the years. Reasons for this uneasiness and lack of trust include technical factors, economics of scale, and cultural differences. Technical factors take two forms. First, concentrates, precipitates, and sponge produced at the mine site are notoriously difficult to sample. A nonrepresentative sample can be the cause of misunderstanding and distrust. Dote, however, is relatively homogeneous and can be correctly sampled and analyzed with greater reliability. Second, the technology and chemistry of fine gold and silver production is complex and quite different from dote production. Most mining companies are content not to be involved with additional processing steps. From the standpoint of process economies, it is easy to see why miners and refiners are separate groups. Mine location is dictated by the natural occurrence of ore bodies. Heavy capital investment requirements for infrastructure in remote locations usually limits companies to produce the first marketable product from a mine. Beyond that point, the economies of scale and large capital investments for refineries generally dictate that the outputs of several mines be combined to feed a single refinery. The refin¬ing process is so complex that refineries are generally built in larger cities with a skilled labor pool. Therefore, only the largest mines can afford to refine their own output. Lastly, there are cultural differences between the miner and the refiner. The miner, particularly the small gold miner, is by definition a risk taker in a risky business. Refineries, on the other hand, have historically been operated under legal or implied monopolies approved by the government. The government is interested in owning gold, either for currency reasons or because many national mints are major users of gold coins. It is not surprising, then, to find that miners may regard refiners as part of an unresponsive government bureaucracy or, worse, as "city slickers." It is easy for the two groups to distrust each other with these different backgrounds. The interface between miner and refiner does exist and affects nearly all precious metal mining companies and most refineries. This paper discusses the technical and economic aspects of the interface. It points out how both parties can improve the relationship. Technical interface Precious metals selectively dissolve to produce a pregnant solution. They are then recovered from solution by zinc precipitation (Merrill-Crowe process) or by absorption onto activated carbon. This is followed by stripping and electrowinning. At this point, the mining company must decide whether to ship precipitates (or sponge) to refiners or to produce a dote. Some factors the company must consider are the ability to sample precipitates, concentrates or sponge, security of storage, and production rates. An important factor is the incremental cost (capital and operating) of converting precipitates or sponge into dote at the mine. Generally, mines prefer to melt precipitates or sponge to dote to avoid prob¬lems associated with sampling them. There are three types of fur¬naces used by mining operators to melt precipitates to dote. The first and most widely used is a sil¬icon carbide crucible heated ex¬ternally with a gaseous liquid fuel. The crucible is easy to use and slag can be skimmed before pouring dote. This simple system is capable of handling 1 t/a (32,000 oz per year) gold. It could cost as little as $20,000. More complex systems could cost up to $200,000. The second type of furnace is the gas- or propane-fired rever¬beratory furnace. This is usually used only by large-scale opera¬tors in the silver business. Precip¬itates in reverberatory furnaces come in direct contact with the flame. The large volumes of flue gas can carry significant amounts of dust and fume that must be re¬moved from the gas before dis¬charging it to the atmosphere. In the days when the Rand re¬finery in South Africa used reverberatory furnaces, the silver leaving the furnace in the form of vapor and fume was estimated at 2.2% of the total silver charged to the furnace. The gold in the gases was about 0.03% of the gold charged. Most of this silver and gold was recovered in the exhaust gas scrubber system. These scrub¬ber systems can be more costly than the furnace itself.

Jan 10, 1986

By S. A. Hoenig

Introduction In an earlier publication, the application of exoelectron technology to the monitoring of dry grinding in a ball mill was reported. Recently, the author has investigated the ball mill problem in more detail with the system shown in Fig.1 . Here, some of the current generated in the ore-ball-water mixture was picked up by the metal chains and served as a measure of the rate of grinding. While the mechanism of current generation has not been completely clarified, a parallel study of electrical effects associated with rock drilling indicated that the major driving force is the zeta potential*, while oxidation of the freshly fractured material provides the remainder of the current. Both of these effects are sensitive to the exposed surface area, and it might be expected that the observed currents would provide a measure of the grinding rate. This "surface area" effect allows the measurement system to be used in any type of rock or ore grinding. Some studies with sulfide copper ore indicate higher currents than those observed with silica sand, but the overall pattern of current versus grinding rate is essentially the same. Experimental Studies The experimental system was set up as shown in Fig. 1. The initial studies were done with silica sand because of its availability and for comparison with the data of reference 1. The sand was sized to an average of 425 µm (40 mesh); a typical charge consisted of 2.5 kg (5.5 lb) of sand, 0.85 L (0.22 gal) of tap water and 2.5 kg (5.5 lb) of iron grinding balls 25.5 mm (1 in.) in diameter. For a typical "run," the mill was loaded with a fresh charge of ore and operated for periods ranging from 10-60 min. During this time, the current was measured with a Keithley 417 picoammeter and a chart recorder. At the end of the grinding period, the charge was removed and sieved to recover the 425, 300, and 212 pm (40, 50, and 70 mesh) fractions which were then drained and weighed. A fresh charge was used for each test and every attempt was made to keep the draining and weighing processes uniform. *The zeta potential is the voltage developed between the surface of a solid particle and the ion solution in which it is immersed. In the case of rock/ore materials in water, the zeta potential is negative.

Jan 1, 1984

By R. C. Emmett

Gravity sedimentation is one of the most widely used unit operations in mineral processing and hydrometallurgy. Properly selected and operated sedimentation equipment can provide probably the most economical means of concentrating solids or clarifying solutions. Because of the variety of different approaches possible, including the use of modern flocculants, it is easy to overlook the optimum approach in selecting equipment. The different types of sedimentation systems that can be used in the minerals field and the sizing methods that are currently employed will be discussed here. Sedimentation applications usually fall into two areas, clarification or thickening. While the two operations are basically similar, the difference in emphasis (a well-clarified overflow as opposed to a highly concentrated underflow) results in significant differences in testing, equipment design, and operation. Clarifiers may be merely simple settling vessels with no special features, other than ample volume to provide the detention time needed for suspended solids to settle out of the feed slurry. Or, they can be designed to employ elaborate solids-contact techniques utilizing coagulants or flocculants to achieve more rapid clarification through the growth of particle agglomerates. Thickeners also are available in a wide variety of designs, with the main differences concentrated in the design of the raking mechanism. Thickeners operating in series (continuous countercurrent decantation or CCD) are used to recover valuable solution or purify the insoluble solids. Tray thickeners are used for recovering fine particulate solids such as alumina seed, but in other applications have been supplanted largely by unit thickeners or inclined plate units. Thickeners and clarifiers sometimes are used for storage of either solids or overflow liquor, or employed as precipitating reactors, such as in desilication applications. The use of flocculants and coagulants is much more common in modern processing plants, primarily due to the reduction in capital costs rendered possible through the use of these reagents. The terms flocculant and coagulant are often used interchangeably; generally, it is understood that flocculants refer to organic, high molecular weight synthetic or natural polymers which are useful in flocculating most suspended solids, but generally are ineffective on colloidal suspensions. Coagulants refer to chemicals such as those commonly used in water treatment, alum, ferric salts, lime, etc., which are usually far more effective on colloidal solids but cannot achieve the degree of agglomeration that is possible with the polymers. In some cases, both coagulants and flocculants are used in order to achieve optimum results.

Jan 1, 1986

By William H. Langer

Nearly every community in the United States is dependent on aggregate (sand, gravel, and crushed stone) resources to build and maintain its infrastructure. Unfortunately, developing aggregate resources to meet societal needs causes environmental impacts. Most environmental impacts associated with aggregate mining are benign. Extracting aggregate seldom produces acid mine drainage or other toxic effects commonly associated with mining of metallic or energy resources. The most obvious environmental impact of aggregate mining is the conversion of land use, most likely from undeveloped or agricultural land use, to a hole in the ground. This major impact is accompanied by loss of habitat, noise, dust, blasting effects, erosion, sedimentation, and changes to the visual scene. Some of the impacts are short-lived, and most are easy to predict and easy to observe. Most impacts can be controlled, mitigated, or kept at tolerable levels and can be restricted to the immediate vicinity of the aggregate operation by employing responsible operating practices and available technology. The intensity of environmental impacts generated as a result of mining are determined in large part by the geologic characteristics of aggregate deposits (geomorphology, geometry, and physical and chemical properties). Mining deposits that are too thin, or contain too much unsuitable material, results in the generation of excessively large mined areas and large amounts of waste material. Mining aggregate can lead to serious environmental impacts in some situations. Some geologic environments such as active stream channels, slide-prone areas, and karst terrain are dynamic and respond rapidly to outside stimuli including aggregate mining. Some geomorphic areas and (or) ecosystems underlain with aggregate serve as habitat for rare or endangered species. Similarly, some geomorphic features are themselves rare examples of geologic phenomena or processes. Mining aggregate might be acceptable in some of these areas, but should be conducted only after careful consideration, and then only with extreme prudence. Failure to do so can lead to serious, long-lasting, and irreversible environmental consequences, either in the vicinity of the site or at locations distant from the site. Environmental impacts caused by irresponsible aggregate mining can compromise mining in an entire region.

Jan 1, 2001

By Earle Faig

Along with other transportation modes, the barge industry will be greatly effected by trends in domestic coal production. Traditionally, coal has been one of the major commodities moved by barge. Now, because of events in the international energy market, coal is finally getting the recognition it deserves as a major component of the country's energy program. Perhaps even more significantly, a series of events have caused other countries to turn to the United States as a source of coal. Although the outlook for coal demand is optimistic, it will be greatly influenced by the ability of the transportation sector to handle the additional traffic. Because of our long experience in moving large quantifies of coal, the barging industry is in an excellent position to capitalize on coal's increased popularity. A brief description of the barging industry should facilitate the discussion of coal as it relates to the barging industry. Barge companies operate on a 40.23-Mm (25 000 mile) river system which includes the East and West Coasts and the Mississippi River System. Included in the Mississippi River System are the Allegheny, Monongahela, Kanawha, Ohio, Illinois, Missouri, Tennessee, Cumberland, Arkansas, Warrior - Tombigbee and Mobile Rivers as well as some smaller tributaries. The Gulf Intracoastal Waterway, which stretches along the Gulf Coast from Brownsville, Texas to Apalachicola, Florida, is also considered part of the inland waterway system.

Jan 1, 1981

By Xinyang Yu

The flotation of diaspore, kaolinite, pyrophyllite, illite and the diaspore-kaolinite mixture were studied with a new cationic organosilicon quaternary ammonium collector entitled QAS222. The acting mechanism of the collector with the four minerals was analyzed by Zeta potential measurement and FT-IR spectrum analysis. The results indicate that the QAS222 was effective in the reverse flotation of the diaspore-bauxite mixture of different Al2O3 -to-SiO2 mass ratios (A/S ratio) at an optimum pulp pH of 11. The potentials of the four minerals increased when they were conditioned in the QAS222 solution; however, the potentials of the three aluminosilicate minerals increased faster than that of the diaspore, especially at pH>9. Furthermore, they were positive in a wide pH range, indicating that QAS222 has a strong adsorption on the surface of the aluminosilicate minerals and thus that these minerals can be floated. The FT-IR spectra analysis further indicates that, besides electrostatic adsorp-tions, formation of the hydrogen bond and ammonium absorptions, chemical adsorptions occur between QAS222 and the aluminosilicate minerals, which allow for the QAS222 to be strongly adsorbed on the aluminosilicate minerals. However, these reactions between QAS222 and diaspore at pulp pH=11 are weaker than those of the aluminosilicate minerals. Thus, surface adsorptions cannot be formed effectively, resulting in reduced floatability.

Jan 1, 2010

By S. Culp, P. Metcalfe

Web technologies and the Internet have revolutionized the computer industry. The Web browser technologies have also moved to portable devices such as Personal Digital Assistants (PDAs) and mobile phones. This paper looks at how to implement a Web Server solution and addresses some of the inherent advantages in the technology. It will also look at some examples of how plant productivity can be managed with a Web Server approach.

Jan 1, 2002

By V. W. Smith

For the past 50 years, the primary crushing of stone at the Dolase Bros. Co. Richards Spur Quarry. 13 miles north of Lawton, Oklahoma, has been accomplished by a Traylor 42-inch gyratory crusher. The production capacity of the primary system, consisting of a feeder, grizzly, and the gyratory crusher, was approximately 2100 tons per hour. Shot-down scone was hauled from the working face about one mile to the feeder by a fleet of Caterpillar Model 773's and WABCO 60- and 65-ton trucks. In order to maintain production, nine to ten trucks and four Caterpillar Model 992 front-end loaders were required to be operational at all times.

Jan 1, 1986

By Duluth Engineers' Club, Engineers' Club of Northern Minnesota

"The early mining of iron ore in Minnesota was carried on with the most primitive kind of tools. The pioneers used only such equipment as could be packed from Duluth through one hundred miles of forest to the first mines on the Vermilion Range and the operations were carried on with picks, shovels, hand drills and wheelbarrows, the ore being hoisted in buckets with a horse winch and carted in horse drawn wagons to the stockpile. This was about the extent of the mechanical equipment of the Minnesota iron mines in the early eighties.As soon as a railroad was pushed through from Two Harbors to the Vermilion Range the equipment began to be improved upon; wood burning steam boilers were installed and small steam puffers displaced the horse-winches, wheelbarrows were aban¬doned and small cars were introduced. Hauling the hoisted ore in wagons was discontinued and trestles were built so that the ore could be stockpiled more cheaply through the use of cars and high piles. These same stockpiles were loaded by hand into the 10 and 15 ton capacity railroad ore cars.Within a few years a marked change took place—the hand drill gave place to the air drill, such as No. 3 Rands, Ingersolls, Sargents and some Sullivans. Tramming was done by mules, the ore hoisted in. self-dumping skips, hoisting engines were intro¬duced and it seemed as though mining as a business in Minnesota had come to stay. At this stage someone conceived the idea of making the stockpile floor about three feet above the top of the ore cars to facilitate the hand loading of stockpile ore for trans¬portation. This was done through the use of wheelbarrows at first and later by using I-ton cars running on tracks laid on the stockpile floor."

Jan 1, 1920

By James W. Bass

Introduction Atmospheric fluidized bed combustion (AFBC) is an improvement over coal-fired boiler design. It offers several advantages over conventional boilers. AFBC can meet sulfur and nitrogen oxide emission regulations without the need for add-on flue gas treatment equipment. The relatively low combustion temperature inhibits ash melting, thus reducing slagging and fouling that can in turn increase a boiler's fuel flexibility. AFBC process The fluidized bed boiler that operates at atmospheric pressure on the fire side (AFBC) is relatively simple and no different in purpose from those pulverized coal boilers used by utilities today. Fluidized bed boilers can generate steam at the pressure and temperature needed by modern steam turbines. Only the firing system is different. In fluidized bed combustion, the fuel can be almost any coal or waste fuel. It is burned in the presence of a bubbling bed of limestone. Air is forced through the bed at a velocity sufficient to support the weight of the bed particles. When the bed is fully fluidized, it bubbles like a boiling liquid. Although the burning coal makes up less than 1% of the fluidized bed, all the bed particles are heated quickly by the turbulence. The calcium in limestone reacts with sulfur dioxide produced in coal combustion to form calcium sulfate in a dry solid state. In this way, sulfur emissions regulations can be met without installing flue gas desulfurization equipment. Boiler tubes submerged in the bed absorb heat directly from the turbulent solids. The heat converts water in the tubes to steam or superheats the steam. Because of the intimate contact of the boiler tubes with the fluidized bed, heat transfer is highly efficient. Consequently, less boiler tubing surface is needed to generate the same amount of steam as in a comparable pulverized coal boiler. The optimum temperature for sulfur capture is relatively low, about 815°C (1500°F) as opposed to 1370°C (2500°F) for pulverized coal boilers. This results in the formation of lower levels of NON. Because operating temperatures are below those that fuse coal ash, a single design can burn a variety of coals without slagging or fouling problems. TVA's AFBC development program Tennessee Valley Authority's (TVA) involvement in AFBC development began in 1974 and has addressed the technical uncertainties through a comprehensive program of design, experimental, and analytical studies. In 1979, TVA and the Electric Power Research Institute (EPRI) developed plans for a 20-MW AFBC pilot plant, a 10-fold scale-up over the next largest test facility. Pilot plant design features TVA constructed the pilot plant at the Shawnee Steam Plant near

Jan 4, 1986

By Ke Yang, Kai Zhang, Xiaolou Chi, Xiangyang Zhang, Yingming Li

Based on the research background of 1303 working face return air roadway in Jinyuan Zhaoxian Mine, Shaanxi Province, a method of determining the reasonable spacing of boreholes is proposed based on the stress transfer degree of coal above and between boreholes, combined with the law of plastic zone and energy evolution by theoretical analysis and numerical simulation. After drilling pressure relief, the average daily energy of microseismic events decreased by 70%, and those with microseismic energy greater than 104 J decreased by 99.2%. The research has a strong guiding significance and research value for determining the reasonable distance of borehole pressure relief.

Jun 25, 2024

By Y. J. Wang

This paper describes a procedure for solving the generalized system of n network equations in n unknowns considering the following ventilation variables and parameters: (a) air quantities, (b) pressure losses or gains caused by the control devices (i.e., fans or regulators), (c) resistance factors, (d) natural ventilation pressure, and (e) fan pressures (as a function of air quantities). The air quantities and pressure losses for all branches in the network are grouped into dependent and independent variables. The branches with an independent quantity are contained in a chord set, and the branches with a dependent pressure loss are contained in a chord set. In addition to the problem formulation, the solution procedure, applying the Newton method, is discussed and illustrated with a numerical example.

Jan 1, 1989

By Donald J. Hill

To be successful, every organization within the mining industry must involve itself in researching and evaluating methods of loss control. The appraisal and evaluation of accidents and injuries is required to determine the costs of loss producing practices and conditions. This involves all of an organizations disciplines that concern themselves with a more efficient and cost effective organization. To come to know the cost of your safety program or how much is expended yearly for each employee on safety; to know what your safety costs are per man-hour or per ton-produced; to know what the health, medical and compensation costs are for any given incident are just a few of the important facts and figures that the safety management of a given organization needs to know to operate in the mining industry today.

Jan 1, 1984

By Robert A. Cummings

Disintegration of the immediate shale roof in coal mines interferes with ventilation, production, and safety. The effect is seasonal and correlates with high levels of moisture in the intake ventilation air. Disintegration, though not completely understood, is caused by shale dilation and weakening upon exposure to atmospheric moisture. Fluctuating moisture conditions are particularly deleterious, and may be at least partially controlled by "tempering" the air before it is brought to the working places. Roof behavior was studied in an operating mine during a 12-month monitoring period. This approach can be used in developing criteria to reduce or prevent shale roof deterioration.

Jan 1, 1981

By S. Svoronos, B. Moudgil, R. Stana, A. El-Midany

Due to their similar surface properties, it is not always easy to separate carbonate minerals from other salt type minerals by froth flotation. A particular example is the difficulty of separating dolomite impunities from phosphate minerals. Such challenging fundamental and practical problems have inspired several research efforts in various laboratories around the globe to find methods for economically removing the dolomite. However, a universal and cost effective process is not in commercial use. In this paper, a new process for separation of carbonate minerals (dolomite or calate) from other associated minerals is presented. Differential solubility of carbonates in slightly acidic solution is utilized to generate micro GO, bubbles at the carbonate mineral/ water interface. Particle (e.g., dolomite)/ bubble aggregates float to the surface leaving phosphate concentrate with low MgO content. Interestingly, up to 6.0 mm particles can be floated by such micro bubble/particle aggregates. Different sutface-active agents were tested to stabilize the bubbles. Results of these tests are presented and the mechanisms involved are discussed.

Jan 1, 2005

By W. H. Schiffbauer

The U.S. National Institute for Occupational Safety and Health (NIOSH) developed an active proximity warning system called hazardous area signaling and ranging device (HASARD) for warning workers as they approach known dangerous areas around heavy mining equipment and other dangerous work zones. HASARD is composed of a transmitter and a receiver. The transmitter generates a 60-kHz magnetic field using one or more wire loop antennas. Each antenna is adjusted to establish a magnetic field pattern for each hazardous area. The receiver, which is worn by the worker, is a magnetic field strength meter. The received signal is compared against preset levels that are calibrated to identify levels of danger. The receiver outputs can include visual, audible and vibratory indicators, and it can also be made to disable machine functions. HASARD was field tested on a Joy 12 continuous miner, a Komatsu 210 M Haulpak and on a high wall launch vehicle. Slight modifications were made for each application. HASARD provided warnings as designed, and it proved to be rugged enough to withstand the harshest of production environments.

Jan 1, 2003