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By M. Hepokoski, M. Klein, L. Yan

"NIOSH research has shown that heat/humidity buildup is a major concern within coal mine refuge alternatives (RAs). These high temperature and humidity levels inside an RA may expose occupants to heat stress. Due to the safety risks associated with testing using human subjects, NIOSH partnered with ThermoAnalytics to create detailed thermal simulation models of RAs with human occupants. The objective of this effort was to predict a miner’s core temperature response and moisture loss in environments that may be encountered in a coal mine RA. These parameters were studied across a range of temperatures and relative humidity values to determine if the current 95°F apparent temperature limit for RAs is reasonable. The results indicated that the 95°F apparent temperature limit is protective, provided that miners are supplied with sufficient water. The results also indicated that the body core temperature did not reach dangerous levels even at an apparent temperature of 130°F. However, the results show that moisture loss increases with apparent temperature. Therefore, if the apparent temperature limit were increased, the water provided in an RA would have to be increased to offset moisture loss. INTRODUCTION The purpose of this effort was to predict a miner’s core temperature and moisture loss (sweating and respiration) in environments that are likely to be encountered in a coal mine refuge alternative (RA). A range of temperatures and relative humidity were studied to determine whether the current 95°F Steadman apparent temperature (AT) limit and 2.25 quart/day water requirements for RAs as mandated by the Mine Safety and Health Administration (MSHA) are reasonable [1, 2]. The effects of metabolic heat rate (activity level), miner size (height and weight), and pose (sitting or lying) on core temperature and moisture loss were also studied. MODEL DESCRIPTION TAITherm thermal modeling software (ThermoAnalytics, Inc.) was used to simulate humans in RA-like environments within a range of temperature and relative humidity combinations. The TAITherm Human Thermal Model (HTM) predicts the dynamic thermal response of the simulated miners while accounting for clothing, human tissue thermal properties, and active thermoregulation. The following sections describe the HTM in more detail, the thermal model setup for this analysis, and core temperature and moisture loss metrics found in published literature. Human Thermal Model Overview The TAITherm human thermal model was used to simulate the heat generated by the shelter occupants, and to predict the miners’ skin and core temperatures along with their sweat evaporation rates. The thermoregulation model simulates the process by which the body attempts to maintain a constant core temperature by considering the effects of shivering, sweating, and changes in skin blood flow. This model calculates surface and deep tissue temperatures within the human body as described by a surface mesh."

Jan 1, 2017

By R. J. Pine

Procedures are described for the application of risk analysis or probabilistic methods to mining geomechanics. The methods are widely applicable to existing mine design models. Detailed examples are given of plane slope failure and of pillar design based on displacement-discontinuity stress modelling and empirical strength assessment. The modelling techniques assessed are the Latin hypercube sampling method, incorporated in a spreadsheet environment, and the general point estimate method (GPEM), programmed in TurboBasic. An example GPEM program listing is included. Both methods are very convenient to use. Probabilistic acceptance criteria for slope stability after Priest and Brown are examined and alternatives are proposed where output distributions of factor of safety are approximately normal or lognormal and output distributions of safety margin are normal. The reliability index is included as a useful measure of variability with proposed acceptance criteria.

Jan 12, 1992

By H. Walqui

This paper describes operating gains resulting from standardizing operating and maintenance practices to improve the performance of the pebble crushing circuit at he Empire Concentrator. Past efforts have led to improved operating time but no additional throughput gains. New Operating standards and checklists were developed and introduced. The content and frequency of the review process indicators was then changed to take advantage of the new practices resulting in an increased feed rate and availability through the pebble crushing circuit.

Feb 27, 2013

By I. E. Odom

The physiocemical properties and industrial uses of the clay mineral montmorillonite are reviewed. Montmorillonite is the most abundant species of the smectite clay mineral group and is the predominant mineral composing bentonite deposits. The crystal structure, chemical composition, exchangeable ion type, and small crystal size are responsible for several unique properties, including a large chemically active surface area, a high cation exchange capacity and interlamellar surfaces having unsual hydration characteristics. The type of exchangeable ion Na, Ca and/or Mg has a major influence on industrial and chemical uses of montmorillonite because of their hydration characteristcs. Natural occurrences of Na montmorillonite in commercial quantities are geographically limited, but Ca-Mg montmorillonite deposits are known world wide. Foundry, well drilling, pelletizing and civil engineering constitute the major uses of montmorillonite, but the total array of uses of montmorillonite exceeds that of any other mineral.

Jan 1, 1986

By Foster Fraas

The objective of this research was separation of one highly conductive mineral from a second conductive mineral , a procedure which is impractical in commercial electrostatic separators using metal rolls . Such separators permit separation of nonconductive from conductive minerals . A new technique involved use of carrier electrode rolls specially prepared by anodizing and / or oxidizing at high temperatures to form suitable oxide surfaces . Specific oxides included aluminum , copper , and nickel . The significant result provided by the new surfaces was the extension of the separation range to higher conductivities , an extension in relative mineral conductivity from 10-14 mhos . The results are in accordance with the blocking- layer theory .

Jan 1, 1964

By Irving Hartmann

At the 9th International Conference of Directors of Safety in Mines Research a paper6/ was presented describing the initial phases of research by the Safety in Mines Research Establishment at Buxton, England, on the remote control of timber fires with high-expansion foam plugs in a rock tunnel. The work received extensive publicity, and great interest was aroused by the implied possibility that the method might be used successfully to control coal-mine fires, which for various reasons cannot be approached and attacked by standard fire fighting measures and frequently require sealing extensive, valuable coal properties and lead to loss of production and coal reserves and occasionally loss of lives. To investigate the practicability of the foam-plug technique under American min¬ing conditions, with room-and-pillar-type extraction and multiple entries, the Bureau of Mines in 1957 began an investigation at its Experimental Coal Mine, Bruceton, Pa, In preparation for this work it was necessary to rehabilitate and reinforce an elliptical tunnel in the mine where studies had been made, many years ago, leading to development of a ventilation system used in the Holland Tunnels between New York and New Jersey, and in many other vehicular tunnels.

Jan 1, 1958

By Donald A. Brobst

Barite, the sulfate of barium, occurs in many geological environments in sedimentary, igneous, and metamorphic rocks. The commercial deposits of barite may be classified into three major types. 1. Vein and cavity fillings that occur in rock fractures, along bedding planes, and in various solution structures. 2. Bedded deposits in which barite occurs as the principal mineral or cementing agent in stratiform bodies in sedimentary rocks. 3. Residual deposits occurring in unconsolidated material formed by the weathering of preexisting rocks. The geologic characteristics of each type of deposit are of fundamental importance to the successful search, development, and economic use of barite deposits.

Jan 1, 1980

The introduction of nitro-carbo-nitrate (NCN) blasting agents has been one of the most significant innovations in the explosive industry in the last twenty years. The most commonly used blasting agent is a rather narrowly proportioned mixture by weight of 94% ammonium nitrate (AN) and 6% No. 2 diesel fuel oil (FO) that is generally designated as ANFO. Other formulations have been developed but none of these have been as extensively used as ANFO. The relative safety of the nitro-carbo-nitrate (NCN) blasting agents almost immediately suggested bulk loading techniques to obtain economies in materials handling. The first attempt at bulk handling was to pneumatically load boreholes with ANFO. When the initial experiments were made in 1957, it was apparent that there were three problem areas which needed study to minimize potential hazards. These were: 1. Static Electricity 2. Fumes 3. Safe Handling Procedures Since those early days, considerable work has been performed in evaluating these problem areas and in arriving at procedures and recommendations that would provide the required safety. Despite the relative insensitivity of ANFO type products, all normal practices for the safe handling of explosives should be obselved. Smoking should not be tolerated in the vicinity of blasting agents and misfires should be handled in the same manner as a misfire with a dynamite charge. The purpose of this Technical Report is to discuss the problems of static electricity and fumes and the solutions that have been developed. Safe handling procedures have been discussed by the Bureau of Mines and are specified by various state and local regulations. Since regulations vary from state to state, the local, applicable regulations must be followed within the area of their jurisdiction. General information is contained in a U. S. Bureau of Mines report, IC 8179, "Safety Recommendations for Sensitized Ammonium Nitrate Blasting Agents" (1963).

Jan 1, 1973

By V. L. Andrade, K. L. C. Goncalves, N. A. Santos

This paper describes results obtained in a test program performed with new equipment, called Mini Pilot Plant, manufactured by Canadian Process Technologies. This equipment was acquired by CVRD aiming at testing flotation circuits, in a continuous closed configuration, with samples obtained from drill cores. Success of this goal would allow CVRD to establish the metallurgical performance of mineral deposits with more confidence in comparison to Locked Cycle Tests (LCT). This paper discusses the importance of assessing the ore variability and compares results obtained in LCTs and Mini Pilot Plant. Results suggest that more reliable data is obtained in MPP test.

Jan 1, 2002

By Ronaldo Câmara Cozza

Iron aluminide alloy; Ball-cratering wear testing; Rolling abrasion; Wear volume; Coefficient of friction

Jul 31, 2018

By C. Alan Tapp

Introduction Mine sampling determines the practicality of any mining operation. Improper sampling can result in an incorrect appraisal of present production and future potential. Therefore, the mine department in charge of ore-reserve calculations and mine sampling should be overseen by competent and experienced professionals with technical backgrounds qualifying them to produce accurate results. Sampling is a process by which portions of an ore body are collected and analyzed to estimate the average mineral content of the entire ore body. It is incorrect to assume that a large number of samples eliminates any errors in the sampling method. To obtain unbiased samples, proper sample location with respect to rock type and mineralization is just as important. The sampling procedure must yield correct results for the type of mineral deposit, and careful consideration should be given to whether or not the sampling technique has been developed to an extent sufficient to eliminate as much human error and bias as possible. Only after the ore has been mined and milled is the sampling accuracy known. Sampling also provides information about the bulk composition of the ore for mineralogical and metallurgical tests that determine the economic ore-waste boundaries and the geologic trends for exploration. Actual mining plans can be developed from this information to maximize profits. Accurate sampling is critical, and thus must be approached in a scientific manner. Sampling Techniques Sampling practices and techniques are as varied as the mines in which they are used. The method(s) chosen must be tailored to suit the company and mining needs. For instance, tabular uranium deposits, vein gold deposits, and porphyry copper deposits pose special problems in conducting unbiased sampling. The mine geologist or engineer in charge must develop a sampling method, test it in a sample area, and then critically evaluate the results. If the results from the test area are accurate within the economic limits established by the company, they then may be adopted for general use in the mine. Four routine sampling methods are suitable for specific sampling objectives in the daily mine routine: (1) channel sampling, (2) chip sampling, (3) grab sampling, and (4) bulk sampling. The final sampling results depend upon how the four methods are combined to accurately determine the grade of the ore body. When used in conjunction with each other during different stages of mine development, the channel, chip, grab, and bulk sampling methods provide an in-house check or a comparison by which mining methods and sampling procedures can be evaluated. However, the most valid check is based upon the daily mill production. Channel Sampling Channel samples consist of cuttings collected from a groove cut into the rock about 102 mm (4 in.) wide and 19 mm (0.75 in.) deep. Various tools ranging from a 1.8-kg (4-lb) hammer and moil to a pneumatic chisel can be used to cut the sample. Accessibility and rock hardness determine the applicable sampling tools. Before attempting to take a sample, the rock surface must be cleaned thoroughly; the method of cleaning depends upon the amount of mine dust accumulated on the surface or the degree of alteration of the rock surface. Typical cleaning methods 'employ a wire brush, water, or chipping a fresh surface. Next, the sample outline is marked on the prepared surface, taking care to choose appropriate sample loca- tions. After determining the proper sample outline and length, the sample can be chiseled out, catching the rock fragments on a canvas tarpaulin on the floor, in a powder box, in a canvas bag to avoid contamination, or by some other suitable means to capture all of the sample. Vertical veins present a special problem because the drift's back usually is arched, not square. For example, Fig. 1 shows that if sample intervals are measured from A' to D', the length of the sample interval is greater than the true vein width, resulting in an incorrect calculation of the ore reserves. The correct method would collect three samples at A'-B', B'-C', and C'-D', using either actual measurements in the mine represented by A-B, B-C, and C-D or trigonometric calculations to determine the true ore thickness. Then, each sample can be weighted by grade and true thickness for the vein. Channel lengths usually are a maximum of 1.5 m (5 ft), and it is good practice to divide longer samples into smaller intervals according to structures, changes in rock types, or differences in rock hardnesses. The influence of those features on the mineralization then can be determined. Chip Sampling Chip sampling is a variation of channel sampling used when the rock is too hard to channel sample economically or when little variation in the mineral content indicates that this sampling method will yield results similar to those of channel sampling. Rather than cutting a channel in the rock, small chips are flaked off at regular intervals over the entire face or area being the mine. sampled. Care must be taken to assure that the sample is representative of variations in the rock hardness and type. hi^ method is fast and useful in preliminary evaluations, but it should not be used for quantitative ore-reserve calculations. Grab Sampling Grab sampling is a fast method for double checking either channel or chip-sampling procedures, and, in some instances, mine production can be estimated from carefully taken grab samples. Grab sampling takes equal amounts of material at selected intervals over a mine dump, a muck pile, or from an ore car to estimate its Channel Sampling mineral content. Generally, this method is not considered reliable. Many independent variables can affect this type of sampling process. Thus, if the ore occurs in the softer fraction and a proportional amount of the result-

Jan 1, 1982

By John Demol

Monazite, a rare earth and thorium phosphate mineral, is one of the major minerals processed for extraction of rare earths. Industry practice for treating monazite concentrates is to use either a sulfuric acid bake or caustic conversion route. In the sulfuric acid bake, monazite concentrate is mixed with concentrated sulfuric acid and roasted. The rare earth phosphate mineral is converted to rare earth sulfate which dissolves in a subsequent water leach. As the bake temperature increases above 300 °C, thorium becomes less soluble. Although acid baking is practised in industry, the bake reactions are not well understood. A combination of chemical analysis, XRD and SEM-EDS was used to identify reaction processes occurring during sulfuric acid baking of a 93 wt% monazite concentrate between 200 °C and 800 °C. The effects of these reactions on the leachability of the rare earths, thorium and phosphate were also examined.

By Sherwin F. Kelly, Bela Low

THE WORK OF THE DRILLER and of the oil geologist is seriously handicapped by the impossibility of actually seeing what is going on inside a borehole as it is being drilled. Visual information of the position and condition of the casing, and of the characters and attitudes of strata passed through would be of inestimable benefit. The best substitute for putting a periscope down a hole is the taking of photographs of its interior at points where information is desired. An apparatus for this purpose has been constructed by Dr. Thomas Reinhold, of Heemstede, Holland, and one instrument of his design has been put into practical use by the Geological Survey of The Netherlands in searching for water. To the best of our knowledge, this instrument has not been applied to oilfield problems, although the possibility has been mentioned in the one or two brief notices of the camera which have appeared in the literature.' The purpose of presenting this description of the instrument, with some examples of its work, is to suggest that it might be adapted to serve a variety of useful purposes in American oilfields, and with the hope that discussion will bring out any modifications necessary to make the apparatus more valuable to drillers and geologists.

Jan 1, 1932

By M. A. Barakat

Large amounts of zinc ash and flue dust containing more than 80 % zinc are accumulated during galvanization processes at the surface of molten zinc bath and in the chimney respectively. Pyrometallurgical recovery of zinc from both of the ash and dust samples has been carried out. The ash was sieved with the help of an industrial sieve shaker provided with mesh sieve having a pore size 0.9 mm. The oversize fraction cut (+ 0.9 mm) was melted at 550 °C under ambient conditions. The produced ingot (1) was analyzed whereas the coarse fraction of the produced slag (+ 0.9 mm) was treated as the coarse ash or added to it. The dust was enriched with suitable fluxing salt prior to heat treatment at 600 °C for 1 h. The produced ingot (2) was analyzed whereas the resulting slag was mixed with the fines of the ash and treated by hydrometallurgical processing to prepare valuable salts of zinc. Parameters affecting recovery processes such as time, temperature and flux percentage were studied. Results obtained revealed that the two prepared ingots (1&2) were successfully recovered with recovery efficiency amounts to =85 %. The obtained samples meet the standard specifications with relatively low price. Also in the light of the strict environmental regulations of pollution control, reuse of these wastes materials will help in keeping the environment clean.

Jan 1, 2000

By S. Qian

Galvanic corrosion is a potentially major concern associated with the application of stainless steel reinforcement which is in direct (electrical) contact with carbon steel reinforcement in concrete structures. Judicious use of stainless steel rebar in both new construction and rehabilitation of older structures is a viable, cost-effective option for extending service life and reducing maintenance costs. Questions, however, had arisen about the possibility of increased corrosion due to galvanic effects. This paper investigates the galvanic-coupling behaviours of three different types of stainless steel and carbon steel. Tests were performed both in electrochemical cells and with specimens in concrete inside an environmental chamber. The results show that oxygen reduction on stainless steel is the rate-determining factor for galvanic coupling of these two metals. It is much lower than that of passive carbon steel. As a result, the galvanic coupling of stainless steel with carbon steel will not increase the risk of corrosion of carbon steel reinforcement.

Jan 1, 2005

By Joseph B. Umpleby

PROGRESS in the petroleum industry in 1929 has been characterized by outstanding accomplishments in the fields of new discovery of supply, economic control of production, increased efficiency and reduced costs of recovery, and lowered costs and greater flexibility in manufacture. Resources have been developed in an outstanding degree in the Kettleman Hills. California, the Oklahoma City field (which adds a large potential area in central Oklahoma), the discovery of Woodbine sand production in East Texas, and the discovery of Wilcox sand production in west-central Kansas. Engineering technique has progressed both along the lines of development and production, with a net result that costs have been reduced and extraction increased in notable degree, although it is impossible to give a close measure of either. In the field of re- fining crude oils variations to the end of promoting reduced cost and greater flexibility has been more important than genera! acceptance of innovations in practice.

Jan 1, 1930

Prof. H. O. Hofman, Massachusetts Institute of Technology, Boston, Mass. (communication to the Secretary): When Mr. Stetefeldt quotes me as saying that " silver-assays are uniformly made by scorification," he has evidently not understood that I was referring solely to the practice of silver-lead smelting-works. Everybody knows that silver-mills do not employ the scorification-assay for regular work ; and it is equally certain that in very few, if any, silver-lead smelting-works will the crucible-assay be found in use for determining silver. The second part of the quotation, "as it is adapted to all kinds of ores and gives excellent results unless organic matter is present," although, of course, also intended in a restricted sense, might very well be extended to a general one. Mr. Furman, in his Manual of Practical Assaying,* says, on page 123: "We believe that the Colorado practice is preferable, as most ores will yield higher silver-results by scorification." The fact that the scorification-assay is the accepted one in Colorado is strong presumptive evidence for its accuracy, as exactness would nowhere else be more jealously demanded. Mr. Stetefeldt cites Albert Arents- as a supporter of his preference for the crucible-assay, although I had already done so in favor of scorification. Looking up again the reference, I find that I was justified in quoting him, as, while Mr. Arents advocates the crucibleassay for low-grade gold ores, not on account of the greater accuracy of its results, but because it is quicker and less expensive, he condemns it§ for the assay of silver-ores, and prefers the scorifier for rich goldores, and for coppery ores, and in general for ores containing both silver and gold. As I, like Mr. Stetefeldt, have kept no detailed

Jan 1, 1895

By P. F. Mataich

"Why bother with computer control?" This question and others like it have been heard over and over again by those who have tried to convince operating men that there are sound merits to installing a process control computer. At IMC we have done a great deal of thinking and talking about computer control. In the course of these discussions the operating people have asked a number of questions about computer control. These questions and our answers to them make up the main part of this article. Obviously, the answer as to whether or not to go into computer control will be an individual problem conditioned by your company's circumstances. What I hope to do here is raise some questions, give you an idea of our thinking on the subject, and lay out some general guidelines for you to consider.

Jan 1, 1965

By Thomas Niehoff, Dave Stoffel

"Energy in the form of natural gas, oil and electricity is expensive and will continue to be a rare resource in the future. Recycling of metals, instead of primary production, is a logical and crucial step towards energy conservation. Energy consumption can be impacted by using advanced combustion systems for metals recycling. Air-fuel combustion has been the conventional method to melt and recycle metals. Global competitive pressures, “greenhouse” gas emissions, and high energy prices force melt shop operations to optimize energy usage and reduce overall operating costs. Oxy-fuel combustion and process technology can be applied to metal recycling operations to meet these objectives. Linde has converted several hundred furnaces from air-fuel to oxy-fuel technology and has extensive experience in optimizing the use of oxygen in furnaces. Additionally, Linde has the process knowledge necessary to avoid costly start-up issues that can accompany the transition to oxy-fuel technology. This paper will describe the benefits and potential issues for conversion to oxy-fuel.IntroductionThe furnace combustion system is the heart of a fossil fuel fired melting process and must be properly matched to the furnace to work as one cohesive unit. Furnaces vary widely in size, shape and features. Rotary furnaces are barrel-shaped and can be designed for tilting or nontilting operation. In a rotary furnace, the products of combustion create a single or double pass through the furnace prior to exiting. Reverberatory furnaces are box-shaped and can also be designed for tilting or non-tilting operation. Reverberatory furnaces are constructed of single or multiple chambers, with or without metal bath movement, and designed for continuous or batch processing. Different furnaces are used for different feedstock materials and products.Furnace combustion systems also vary in many ways. Combustion systems can be of air-fuel or oxy-fuel based technologies, or a combination of the two, resulting in an air-oxy-fuel system. Each of these types of systems has different combustion characteristics which can produce very different results. Here we will describe specific differences in melting processes and their associated energy requirements."

Jan 1, 2009

By P. Saha, D. M. Chakrabarti, J. P. Srivastavam, P. Bhattacharyya, B. R. Sarkhel, Banerjeem B.

The phosphatic soil deposit at the Sukulu hills region of Uganda contains 10-12% P2O5. The ore occurs as a naturally degraded soil deposit containing a very sticky slime composed of earthy lateritic minerals. Desliming of the ore, which is imperative for its further beneficiation, is an extremely difficult hurdle to overcome for its commercial utilisation. Earlier studies on samples of the same ore at the National Metallurgical Laboratory (NML) and abroad established that it was necessary to pass the ore through a series of three stages of desliming, each consisting of a step of vigorous attrition scrubbing followed by hydrocycloning, for effective elimination of the sticky slime. In the present paper an innovative use of the very strong shear-fields created inside a hydrocyclone has been discussed, that could effectively eliminate the stubborn slime from the ore. The standard design of the hydrocyclone was suitably modified to increase the shearing effect on the slurry. It was possible, through the application of this modified hydrocyclone, to not only totally eliminate all the stages of attrition scrubbing, but also to reduce the subsequent stages of hydrocycloning. The modified technique yielded a concentrate of grade comparable to that obtained by employing the earlier more complex flow sheet, with about 25% higher P2O5 recovery.

Jan 1, 2003