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By J. R. Batista

Leachates from gold heap-leaching mines contain selenium concentrations as high as 2 mg/L. Previous studies report satisfactory selenium adsorption by activated alumina when using relatively "clean" drinking waters. However, the findings of these studies cannot be directly applied to the treatment of mine leachate where other ions compete for the alumina adsorption sites. This study evaluated the adsorption of selenium from a mine leachate to develop design parameters for full-scale activated alumina processes. The study revealed that 68% of the selenium in the leachate could be removed by alumina at pH > 5.0. Silica adversely affected the selenium adsorption capacity. At pH values < 4, silica was poorly adsorbed by alumina and selenium adsorption was improved.

Jan 1, 1994

By Jim V. Rouse

Adverse water-quality impacts of uranium mining and milling activities on both surface- and ground-water resources in the Grants Mineral Belt have recently been documented.1 In some cases, the impacts resulted in violation of existing regulations and license conditions and have endangered public health. Unfortunately, industry-sponsored ground-water monitoring programs do not adequately record the actual impacts of mining and milling on ground-water quality.

Jan 1, 1976

By Niles E. Grosvenor

One of the most important considerations in the efficient operation of an under¬ground mine is the haulage system. Often the determining factor between profit or loss is the quick removal of ore and waste from the working places to secondary and main-line haulage areas, and so on to the outside. Important, too, is moving supplies from the surface to the working faces so that the loading process can continue with little interruption. Men must he transported in a rapid but safe manner. It has been through the efficient use and generally the combination of mine cars, track, belt conveyors and rubber-tired haulage equipment that underground operations have been able to compete with the more popular strip or surface mining. As near-surface ore bodies are exhausted, underground haulage will play an expanding part in economically furnishing the world&apos;s needs for all types of minerals. The choice of underground haulage equipment, wherever possible, should be one that will give the smallest overall cost of ore removal during the life of the mine while meeting necessary safety requirements. The reader is referred to Sec. 12 for equipment such as scrapers and load-dump-¬haul units that perform loading as well as haulage duties. 14.1-MINE CARS AND TRACK NILES E. GROSVENOR Main-Line and Secondary Haulage-Many mines today use a combination of belt and rail haulage. Even if a- belt system is used to carry the product from the face to the surface, track is used to transport workmen and supplies. A track system, when properly installed, will provide interruption-free and safe haulage. Schrecengost 2 lists the following as major advantages of track haulage: 1. Safety in transporting men in and out of the mine in personnel cars. 2. Easy and rapid transportation of supervisory personnel. 3. A temporary shutdown occasioned by a roof fall or power failure along the haulage system will not shut down the production areas. 4. Quick availability of repair parts and supplies. 5. Large pieces of coal or rock can be handled without damage to the haulage equipment. 6. In areas where quality fluctuates noticeably, different cars may be separated out for special preparation. 7. Rock or equipment may be loaded and moved out of the mine without interference with the production or preparation of the coal. 14.1.1-MINE CARS Mine cars with steel bodies are used in all types of present-day mining. Wooden cars usually are more bulky and less resistant to wear and damage, but are more easily repaired. Regardless of the type of mine car selected, it is most practical to standardize on one type or make to simplify repairs and limit the amount of spare parts necessary to stock. Rigid-body flat-bottomed cars are simpler and usually lower than others of equal capacity. Advantages are: ease of loading because of the low sides, simplicity, cheapness and high ratio of capacity to weight. The disadvantages include the

Jan 1, 1973

By William E. Robinson

Our earthly treasures are being quickly depleted. We have experienced what can happen in an energy crisis. You have read and heard all kinds of stories as to what caused this crisis. On the surface it would seem that all of a sudden a situation becomes a crisis whether it be fuel, potatoes, beef or whatever. Well, of course, they don&apos;t just happen. There is always a little fore-warning here, an indicator there. Someone recognizes a sign of potential trouble but is ridiculed when he forecasts it. We are running out of sand: Producers of aggregates who can say today ... "That couldn&apos;t happen to me", can well be awakened tomorrow to the cold fact of reality. It could come from any number of directions. Depletion is mostly foreseeable but zoning isn&apos;t. Legislation can also be sudden death to availibility. With the ever growing population moving into the rural countryside, available deposits are being sold either to developers or being zoned for restricted use. The fact that a gravel pit or quarry is located on a particular plot has not fazed some of the local planning boards when they decided to place the adjoining property in a residential Zone A. Proponents of zoning preach that such use is necessary to insure that the land will be put to its best use. Planning boards establish the best places for schools, homes, shopping areas, factories, etc., so that the individuals or groups are in harmony with each other. This is usually done to date without thought or consideration to the geological importance or potential of the area. Today over half of the United States is living under some form of land use restriction. Little consideration has been given to what lies under the ground to be zoned. Fortunately, the states are slowly getting around to geological surveying. I feel that it is about time that state and federal authorities institute governmental restrictions to prohibit or control local zoning ordinances which would deplete or deny an area of its natural resources. While I could continue for the balance of my time just on this facet of our industry&apos;s problems, my point is: How sure are you of your next load of sand? I could be well laughed at by some of you for saying that there is an alarmingly rapid disappearance of "nearby" sand and gravel reserves in many areas of the country. A questionable statement, except to those producers where depletion has already taken place.

Jan 1, 1974

By K. E. Harrison

The acid rain legislation has passed into law. This new law has caused the power generation community to investigate alternative methods to obtain compliance with the new legislation. One thing all of the power companies have concluded is the answer is not easy. Do we switch fuels to burn all low sulfur compliance coal? Maybe possibly only partial desulfurization by means of a dry sorbent system? Or, finally, maybe a wet scrubber system? Whatever the choice, the power community needs to investigate all of the alternatives. In 1988, ICF Kaiser Engineers, Inc. (ICF KE) responded to a request by the U.S. Department of Energy for the engineering development of advanced physical fine coal cleaning. ICF KE responded and was awarded a contract to conduct a multi-task program to develop an advanced flotation system to eliminate pyritic sulfur and retain as much energy as possible. ICF KE assembled a team that included members of industry, academia, and industry research organizations to conduct this multi-task program. The program includes sixteen (16) tasks. This team had personnel to help solve some of the anticipated problems and to provide industry prospective on the viability and commercial potential for any concepts proposed. The primary team consists of a major coal producer, Babcock and Wilcox, Eimco Process Equipment Company, and Virginia Polytechnic Institute and State University.

Jan 1, 1992

By J. P. Allen

Cobalt, nickel, and manganese can be recovered quickly, cleanly, and selectively from cobalt-rich manganese crust by leaching in dilute acid solutions in the presence of hydrogen peroxide. Common selective precipitation methods can then be used to recover these metals from the leach liquor. The leaching reaction produces only oxygen as a byproduct, and the waste residue from leaching was tested and found to be non-hazardous under existing EPA specifications. The leaching process is effective in either fresh water or seawater. This research is a part of the Bureau of Mines program to identify the mineral resources of the Exclusive Economic Zone and devise methods for recovering their valuable components.

Jan 1, 1990

By Subhash Bhagwat

The definition of high sulfur coal varies from plant to plant and is subject to changes over time as the environmental regulations change. In plants constructed after September 1978 hardly any domestic coal can currently be burned without the use of Flue Gas Desulfurization (FGD) because a 70 percent reduction in potential S02 emission is mandatory even when the potential emission is less than 0.6 lbs. S02/106 Btu heat input. On the other hand older power plants may in many cases be legally emitting up to 6 lbs. S02/106 Btu or more under some State Implementation Plans (SIP). The Clean Air Act requires, however, that in the long run all stationary sources of S02 pollution must abide by the ceiling of 1.2 lbs S02/10 Btu heat input.. Coals with a potential to exceed this limit must, therefore, be considered as high sulfur coals. Such a definition would be unrealistic because many SIP&apos;s aim at an emission level of 1.8 to 2.0 lbs. SO2/106 Btu for existing plants and a stricter limit does not appear to be enforceable in the next 5 to 10 years. As a result, coals with an emission potential of greater than 2.0 lbs of S02 per 10 Btu heat input are considered high sulfur coals for the purpose of this investigation. Based on this definition and the 1984 actual consumption of coals by U.S. electric utilities (table 1) only 7 out of the 24 coal producing states could be categorized as low sulfur states. The actual S02 pollution, however, depends on total tonnage of a type of coal as well as the sulfur content of the coal. Table 1 also indicates that only 6 states--Kentucky, Illinois, West Virginia, Ohio, Pennsylvania and Indiana-account for nearly 77 percent of S02 pollution potential in the United States. These 6 states have therefore been chosen for this investigation.

Jan 1, 1986

By John O. Marsden

"This article is an attempt to capture a presentation given at the 2016 SME Mineral & Metallurgical Processing Division (MPD) Luncheon held on Feb. 24, 2016, in Phoenix, AZ. It was presented as a tongue-in-cheek, lighthearted view of several of the issues facing our industry, while identifying some of the challenges and opportunities available to new engineers entering the industry today.Disclaimer• What you are about to read includes personal preferences, biases and occasionally arbitrary opinions.• Some readers may have dissimilar opinions on the contents and/or the rank order of the lists.There are eight top ten lists offered in this article: (1) Industry realities (2) Things a metallurgical or mineral process engineering graduate should do (3) Books every metallurgist should have on their shelf (4) Things I wish I had known (5) Legends of metallurgy (posthumous, with highlights) (6) Things we’ve forgotten (7) Mineral processing innovations of the past 20 years and, finally, (8) The future? For some items, additional context or clarification is provided after the item, while for other items no further explanation is warranted and none is offered. Top 10 industry realities1. Metal price cycles.2. Bigger is better (except when it isn’t).3. Ore grades declining across the board of metals/commodities.4. Ores becoming more complex.5. Three-fold increase in capital costs between 2004 and 2015.6. Three-fold increase in operating costs between 2004 and 2015.7. Less capital availability/challenging financial markets.8. Environmental constraints increasing.9. Socio-political constraints increasing.10. The mine manager is always impossible to work with.As Table 1 shows, there was more than a three-fold increase in gold operating costs between 2004 and 2014. The increases for copper, iron ore and other commodities were similar."

Aug 1, 2016

By Subhas G. Malghan

Feldspathic deposits occur widely throughout the United States, but North Carolina, California, Connecticut and South Carolina accounted for over 80% of the total domestic feldspar output for the year 1973.1 Pegmatites and granites constitute the major feldspar reserves of the United States,2 and in addition, feldspar is produced as a by-product by firms whose major products are spodumene and mica.3 Feldspar is concentrated by hand-cobbing and flotation; the latter forms the major method of separating and concentrating feldspar. Feldspar flotation is practiced in the United States, Mexico, Finland, Norway, West Germany, Japan and the USSR. According to the U. S. Bureau of Mines estimates, the production of feldspar in the United States and rest of the world were 704,000 tons and 2,514,000 tons respectively. Feldspar is principally used as a flux in making glass, pottery, porcelain, enamel,-tile and other ceramic products. In recent years, the domestic feldspar industry is faced with a number of problems. As a result of increased cost of energy and the introduction in 1972 of new legislative programs relating to air, water, and noise pollution, land-use restrictions, and mined-land rehabilitation, the production costs have increased. Apart from the increased cost of operation, an operational problem exists with the feldspar producers in North Carolina, especially those in the Spruce Pine area. This problem is concerned with the use of hydrofluoric acid in the feldspar flotation. Feldspar producers in Spruce Pine, North Carolina have been discharging process waste water into the North Toe River. The mill waste water contains active fluoride ions. Fluoride in excessive concentrations is undesirable in waters used for drinking. It is stated that water

Jan 1, 1976

By George S. Koch

We evaluate the exploration effort by diamond drilling for zinc in central Tennessee and southern Kentucky through a statistical analysis comparing the Middle Tennessee district with the older Tri-State and Upper Mississippi Valley districts. All of the ore deposits are of the Mississippi Valley type and are similar geologically. Through statistical analyses we attempt to answer these questions: Had the drilling density in the Middle Tennessee district been applied to the Tri-State district, how much of the ore in the Tri-State would have been discovered? Had this drilling been done in the Upper Mississippi Valley district, how much of the ore in that district would have been found? Which of these two older districts does Middle Tennessee more closely resemble in intensity of zinc mineralization? Is more drilling warranted in the Middle Tennessee district? Our data base includes tonnage and area distributions of ore deposits in the Tri-State dis¬trict, sizes of ore bodies and probabilities of their recognition in the three districts, and data for the Elmwood mine in the Middle Tennessee district. Our statistical analysis considers the consequences of drilling holes in the three districts on square grids at coarse, intermediate, and fine spacings. We conclude that the drilling pattern assumed for Middle Tennessee would have found some but not all of the ore in the two older districts. We believe that in intensity of mineralization Middle Tennessee more closely resembles the Tri-State than the Upper Mississippi Valley district, and that more drilling is warranted in the Middle Tennessee district.

Jan 1, 1979

By Langtry E. Lynd

The titanium industry is based on the unique properties of titanium dioxide and titanium metal. Because of its whiteness, high refractive index and resulting light scattering ability, titanium dioxide in its two main allotropic forms, rutile and anatase, is the predominant white pigment for paints, paper, plastics, rubber, and various other materials. Titanium metal, because of its high strength/weight ratio and resistance to corrosion, is widely used for aircraft, both in airframes and engines, for powerplant surface condensers, and a wide variety of chemical processing and handling equipment. U.S. production of titanium dioxide pigment in 1979 was about 658,000 tons - 2/, valued at about $770 million. Net shipments of titanium mill products were around 19,000 tons, worth about $380 million. These two major uses account for over 96% of domestic titanium consumption. The third largest application, the use of rutile for coating welding rods, required about 9,500 tons of rutile concentrate, worth about $4 million. Other applications of titanium-bearing raw materials include the manufacture of titanium carbides, ceramics, and chemicals, and the recently developed use of ilmenite as a substitute for barite in well-drilling muds.

Jan 1, 1980

By J. E. Urosek

In October, 1990, a fire started in a large underground coal mine in Western Pennsylvania. During fire-fighting activities, an explosion occurred and all personnel were evacuated. Safe re-entry into the mine was not possible and the mine was sealed. Recovery efforts began in January, 1991 and continued until March, 1991, when permanent underground seals were installed between the fire area and the mine openings. This paper describes an extensive atmospheric monitoring program conducted by the Mine Safety and Health Administration (MSHA), Pittsburgh Safety and Health Technology Center (PS&HTC) including the analysis of mine fire gases, natural ventilation, fan pressure and air quantity distribution.

Jan 1, 1993

By Simon E. Rodriguez

This paper presents sulfur isotope data obtained for the deposits and country rocks of the Bailadores and Aroa Mining District, Venezuela. The study is a part of an extensive geochemical investigation of the mineralized belts that has as their aim the elucidation of the genesis of ores. The Bailadores deposits are located at about 600 Km. west-southwest of Caracas, or about 10 Km. southeast of the Town of Bailadores, Merida State (Fig. 1). The mine concession is held by the Ministry of Mines and Hydrocarbons (De Lima I, De Lima II and La Cascade areas). In a straight distance the mine is about 90 Km. southwest of Merida, the capital of Mérida State. From Mérida to Bailadores, through La Victoria and Tovar, it takes 3 hour by car. From Bailadores to the mine site it is about 40 minutes by jeep. The Aroa deposits are located at 4 Km. east of Aroa Village, Yaracuy State, about 220 Km. west of Caracas. It is 83 Km. from San Felipe, the capital of Yaracuy State to the mine (Fig.2). The mine is about 600 m above sea level, situated on the northern foot of the E-W trending Andes. The topography of the mine are shows a mature stage and is somewhat rugged. As the climate is warm and humid, the area is thicky covered with jungle.

Jan 1, 1974

By Dale R. Ralston, Roy E. Williams, Gerry V. Winter, George L. Bloomsburg

INTRODUCTION This manuscript is based on site inspections of five existing mines and the detailed analysis of two of the five. The detailed analysis and mathematical models of the two mines are presented herein in order to demonstrate a method of predicting mine water inflow using existing mines as a data base. Water management procedures were studied at all mines. Our original criteria for mine selection were that the mines be less than five years old and have an inflow rate in excess of 2000 gpm (7.6 m3/min). Background hydrologic and hydrogeologic data were required so that two of the mines could be used for our computer modeling experiments. Our original criteria proved to be difficult to meet. We contacted numerous mines via various sources. Many mines were unable to meet the cri¬teria stated or were not interested in cooperating with us. Therefore, we allowed some flexibility in the application of these criteria to satisfy our orig¬inal requirements. Although the visitations at all the mines are not discussed herein the characteristics of the two mines simulated are presented. These simulated mines consist of a uranium mine in New Mexico and a lead mine in Missouri. The mines and owners will remain anonymous by request. URANIUM MINE-CASE HISTORY NUMBER 1 Mine Location The uranium mine that we simulated is located in northwestern New Mexico. The ground surface at the uranium mine is at an elevation of approx¬imately 7000 ft (2134 m) above mean sea level. The climate is arid to semi-arid with an average annual precipitation of approximately 10 in. (25.4 cm) (John and West, 1963). Geologic Setting It is essential that a conceptual model of the stratigraphy, hydrostratigraphy, and structural geology of a mine site be developed prior to simulation by a mathematical model. If such a conceptual model is not developed prior to simulation major errors are difficult to avoid. The uranium mine we have simulated is located in the San Juan Basin (Fig. 68), which is a structural basin located in northwestern New Mexico and adjacent parts of Colorado, Arizona, and Utah. The sedimentary rocks present in the deepest part of the basin are nearly 15,000 ft (4572 m) thick (John and West, 1963). The regional dip of the sedimen¬tary rocks in the Grants area is generally northward toward the San Juan Basin; the regional attitude is modified locally by normal faults and folds (Hilbert, 1963). The rocks of interest in this area are sedimentary in origin and range in age from Penn¬sylvanian to Cretaceous. They rest on the Precam¬brian core of the Zuni Uplift. Associated intrusive and extrusive rocks are of Tertiary and Quaternary ages (Hilbert, 1963). The deepest sedimentary unit of interest at this mine site is the Morrison Formation as described by Hilbert (1963). The Morrison Formation con¬sists of three members in the general area of the mine site; the deepest member is the Recapture. The Recapture Member consists of alternating beds of gray sandstone and grayish red siltstone or mud¬stone with strata up to several feet in thickness. Only a few small deposits of uranium are contained within the Recapture Member. The Westwater Canyon Member overlies the Recapture Member of the Morrison Formation. The Westwater Can¬yon Member is approximately 150 ft (46 m) thick and consists of light brown to gray, poorly sorted, arkosic sandstone, and some interbedded gray mud¬stone. The Poison Canyon Formation denoted in subsequent discussions, tables, and figures was de¬termined to be a part of the Westwater Canyon Member. The separate connotation is used for the description of mining operations and hydraulic properties but a separate physical description is not included. This member of the Morrison Formation contains many large deposits of uranium. This is (some pages in this article are damaged)

Jan 1, 1986

By V. A. Kharchenko, V. M. Yeremeev

INITIAL PRECONDITIONS To solve tile problem of using the potential reserves of the different coal ranks efficiently (the coal reserves being many times superior in quantity to those of natural gas and oil) one must realise an integrated estimation of the coalfields&apos; and coal deposits&apos; reserves. The actuality of this problem increased especially in the recent years, when the Russian coal industry is being restructured. A structural reorgaisation of this industry, in order to in- crease its efficiency, covers a large spectrum of social and economic problems, comprising a withdrawal from mining the coal reserves that are unsafe from the standpoint of economy and labour protection. According to the information supplied by the &apos;Rossoogol&apos; company, the Russian coal industry, accounting for abut a fifth of the world coal reserves, has a rather unsafe resource base, for about 5% of the reserves involved in mining do not correspond to the world practice conditions, regarding the coal grade, thickness, geological conditions, proneness to coal and gas outburst hazards. These concern first of all the Moscow, Kizelovsk and Donetsk coal basins, the Prokopievsk-Kiselevsk district of the Kuzbas basin and several other coalfields. Thus, the problem of efficient potential coal reserves&apos; utilization calls for a paramount solution of two basic problems, namely: a) a comparative coalfields&apos; and sections evaluation, and their ranging, in accordance with their industrial importance; b) choosing the &apos;active&apos; reserves good to be efficiently mined under the present-day conditions. PRINCIPLES OF EVALUATION The investigations that had been carried out make it possible to formulate the following basic principles of the coalfields&apos; reserves&apos; estimation (or assessment). 1. The necessity, possibility and expediency of coal reserves&apos; industrial exploitation are determined by a set of natural, technical, technological, practical, economic, environmental and social factors, thus calling for an integrated and gradual approach to problem solving. 2. One cannot consider the results of same reserves&apos; estimation as being invariable because the former depend both upon constant (mainly natural) and market demands for different grades of coal (those of different power engineering and technological situations), capital investments, material and labour resources, economic (price-forming), technical, technological, environmental and other factors. 3. The rational size and sequence of the operating mines&apos; and reserve sections&apos; resources&apos; involvement into mining depend upon the final aim of posing the problem, whose variants may be (the corresponding limitations being considered) providing for a maximum run-of-mine output (these essentially featuring the past stages of the industry&apos;s evolution); providing for a maximum efficiency, measured possibly by the specific or absolute indices of profits an expenses, labour productivity e. al. ; providing for a maximum extraction (maximum integrate utilization) of the known reserves. In this case an important park goes to the economic evaluation (or assessment) of useful application of the by-products being extracted (methane, mine water, rack) compared to the expenses necessary for their utilization. Regarding the steam coal (posing the problem any way it be possible), and extreme limit to the absolute non-efficiency of the coal reserves&apos; exploitation may be posed, using the proportion of energy obtained from the possible amount of the coal to be extracted to the energy consumption necessary to extract, prepare, haul and consume this amount of coal. 4. The most reliable and efficient solutions providing for opening the reserves can be obtained for group of mines, rather than at the level of an individual mine section or an individual mine because it is only in the former case that the possibilities to re- distribute the expenses necessary to develop the good for mining and worse sections and seams can be realized to the greatest extent. Therefore the prospective approach to be considered is the one providing for an integrated organization and choice of the optimum combination of the variants of the ways to use the mines in operation and the free sections of the region in order to satisfy the growing up requirements for coal rather than the one providing for individual mine sections&apos; resources&apos; evaluation. 5. The future possibility and expediency of coal reserves&apos; industrial exploitation will depend upon the prospects to implant at the mines in operation and reserve sections new engineering and technological elements and coal extraction technologies which may essentially change the actual idea concerning the coal reserves worth of being developed in an efficient way. For example, reserves not available to be exploited using conventional coal extraction technology may be regarded as potential resources for in situ gasification, e. g. the operating mines&apos; reserves (non-commercial and non-mined commercial ones), balance and outside balance reserves of the free sections having proved not available to be mined using conventional coal-extraction technologies, as well as the non-extracted reserves of the abandoned and closed mines.

Jan 1, 1996

By Omar. M. Arafat, Edgar Pérez, Kyle. M. Bartholomew, Robert. E. McIvor

The “circulating load” confounds understanding of ball milling circuits. Conflicting opinions exist as to its role. Should it be high, or low? Why does it even exist? It is commonly accepted in the plant as a given, the outcome of largely unknown factors. As such, it may often go unmeasured or even ignored. This paper describes the importance of the circulating load in wet ball milling circuits. It is characterized not only in terms of solids mass flow (or ratio of mass flows), but also by its other key physical characteristic, its size distribution. Its effect on grinding circuit performance is explained. The equipment application design steps to achieve a desired circulating load, in terms of both its mass flow and size distribution, are described. Finally, its pivotal role in grind control is specified. Our goal is for the reader to come away with a fresh understanding of the role of the circulating load in wet ball milling circuits, including how and why it should be measured and managed.

Feb 22, 2026

By Paul Shimizu

BHP Robinson contracted Minnovex Technologies to implement a Comdale Expert System at their greenfields operation in Ely, Nevada. The expert system has resulted in a significant increase in tonnage. Other benefits have also been realised, including a reduction in operation upsets (having a positive effect on downstream processes, i.e. flotation) and reduced production variances between crews. The expert system is written in a unique manner using trend based logic with minimal hard limits. The result is a robust system that requires minimal operator supervision while producing very high results. The development, success and acceptance of the system can be attributed to the strong team that was assembled for this project. The team not only consisted of BHP Metallurgists and Minnovex but most importantly included operations.

Jan 1, 1998

By G. Southam

Bacterial populations play an active role in mineral weathering in subsurface and near-surface environments e.g., supergene enrichment of Cu at Morenci, AZ. An in vitro bacterial biofilm model was used to examine the interaction between Sporosarcina ureae and ionic gold (which is toxic) or amino acid-gold complexes in gold mobility. The immobilization of ionic gold was between 80-90% for 1 week but as the available, cellular reactive sites became saturated immobilization decreased to 14% within 2 weeks. In the asparagine-gold system, gold immobilization occurred at a high rate (80-90%) throughout the experiment with limited toxicity towards Sporosarcina ureae.

Jan 1, 1999

By Mahiyar Nasarwanji, Jonathan K. Hrica, Jonisha P. Pollard, Lydia M. Kocher, Brianna M. Eiter

Within the metal/nonmetal mining sector, fall-related incidents account for a large proportion of fatal and nonfatal injuries that occur in mining in the United States. However, the events and contributing factors leading up to these incidents have not been fully investigated. To help provide a clearer picture of these factors, an analysis of imminent danger orders issued by the U.S. Mine Safety and Health Administration (MSHA) from 2010 through 2017 at both surface and underground metal/nonmetal mine sites revealed that most orders are associated with fall risks. Of these cases, 84 percent involved the workers not using fall protection, fall protection not being provided or the improper use of fall protection. Fall risks for workers most frequently occurred when standing on mobile equipment, performing maintenance and repairs on plant equipment or working near highwalls. In most cases, a single, basic, corrective action — such as using fall protection — would have allowed workers to perform the task safely. Overall, these findings suggest that a systematic approach is needed to identify, eliminate and prevent imminent danger situations. Furthermore, to protect mineworkers from falls from height, frequently performed tasks requiring fall protection should be redesigned to eliminate the reliance on personal fall protection.

By T. J. Lutz, L. Yan, J. R. Srednicki, J. A. Yonkey, G. T. Homce

"Federal regulations require the installation of refuge alternatives (RAs) in underground coal mines. Of the in-use RAs, over 95% are mobile RAs with the remainder being built-in-place (BIP) RAs. Heat/humidity buildup has been one of the major concerns with mobile RAs. For BIP RAs, however, there is a lack of in-mine heat/humidity test data to determine the extent of heat and humidity buildup. To quantify heat/humidity buildup in BIP RAs, the National Institute for Occupational Safety and Health (NIOSH) performed a series of heat/humidity tests on a 60-person BIP RA with and without a borehole air supply. At various times during the year, tests were performed with cooled, heated, or unconditioned borehole air to examine how various outdoor temperatures may affect the thermal conditions inside a BIP RA. The results show that the air supplied to a BIP RA may require heating and cooling, depending on the outside air temperatures and the temperature of the mine. For example, during tests with an external ambient temperature above 70°F and a humidity that reached 90 %RH, providing 55°F dew point air was able to keep the internal apparent temperature below the mandated 95°F. Results for each test case are presented. INTRODUCTION The Mine Safety and Health Administration (MSHA) has required the installation of refuge alternatives (RAs) in underground coal mines since 2008 [1]. MSHA requires that RAs provide an environment with breathable air for entrapped miners for a 96-hour period. Heat buildup inside an occupied RA is a serious concern. Without a means to dissipate the heat and humidity generated by the occupants and the carbon dioxide scrubbing system, the temperature and humidity inside RAs could lead to severe discomfort or heat stress depending on the mine ambient temperature before and during occupation of the RA. In its 2006 report, the West Virginia Mine Safety Technology Task Force recommended an apparent temperature limit of 95°F for RAs [2]. In 30 CFR 7.504, MSHA specifies a maximum apparent temperature of 95°F inside an occupied RA [3]. The apparent temperature is calculated using both air temperature and relative humidity [4]. To determine if their RAs meet the apparent temperature limit, RA manufacturers have been performing 96-hour-long heat and humidity tests in laboratories. During these tests, a heat input of 117 W (400 BTU/hr) per person is used to represent the metabolic heat of a single miner [2]. The heat generated by the RA’s carbon dioxide system is also accounted for in testing. To account for this heat, 50 W (170 BTU/hr) of heat per miner is used for a lithium hydroxide scrubbing system, or 30 W (100 BTU/hr) of heat per miner is used for a soda lime scrubbing system [5]. In these tests, air velocities around the RA are minimized to represent the worst-case scenario of an interruption in mine ventilation that might occur in a mine disaster."

Jan 1, 2017