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"A commercially available through-the-earth (TTE) communications system was evaluated at an active underground longwall mine in West Virginia. This TTE system uses electricfield (E-field) sensing to send text-based communications through two separate antenna arrays connected in parallel. Each antenna array is composed of interconnected, grounded metallic rods or other such structures. Two-way communication between subsurface locations was investigated in this study using various antenna configurations. This field study was conducted as a part of a larger multisite evaluation of available TTE systems in an effort to determine their operational sensitivities. IntroductionWireless, through-the-earth (TTE) communication technology is designed to achieve point-to-point communication through solid strata using very low frequency (VLF) and ultra-low frequency (ULF) electromagnetic waves. Using this approach, communications are established without the need for intermediary communications infrastructure. As a result, TTE systems have the potential to provide reliable, robust communications between surface and underground personnel. Exploration into the use of TTE technology for this purpose dates back to the 1920s (Jakosky and Zellers, 1924; Pittman, Church and McLendon, 1985), but U.S. permissibility requirements slowed the development of TTE equipment for widespread implementation (Durkin 1980; Pittman, Church and McLendon, 1985). One of the primary challenges in producing wireless TTE communications is the counteraction of signal attenuation when propagating through solid strata (Barkand, Damiano and Shumaker, 2006; Wadley, 1949). The long wavelengths of TTE transmissions make them well-suited for reducing the rate of attenuation. However, even when operating within the VLF to ULF range, the performance of TTE systems is still affected by geologic and anthropogenic factors (Geyer, 1973; Geyer and Keller, 1976; Geyer, Keller and Ohya, 1974; Jakosky and Zellers, 1924; Large, Ball and Farstad, 1973). Although commercially developed TTE systems have demonstrated the ability to communicate in a variety of conditions, their range and performance have been highly varied (Barkand, Damiano and Shumaker, 2006; Geyer and Keller, 1976; Geyer, Keller and Ohya, 1974; Ilsley, Freeman and Zellers, 1928; Jakosky and Zellers, 1924; Yenchek et al., 2012)."

Sep 1, 2016

By S. K. Mohanty, T. M. Dittrich, M. J. Allen, M. Dardona, A. C. Strzelecki, J. Hovey, Boukhalfa. H.

Rare earth elements (REEs) have many critical uses in advanced technology and the lack of a reliable domestic supply has been identified by the US DOE as a vulnerability to US economic security. Our research focuses on developing an economical process for extracting REEs from coal fly ash and power plant wastewater sludge by coupling a hydrothermal extraction process with the engineering of a ligand-associated media for concentrating REEs from the extraction liquid. Ash samples have been collected from two Detroit-area Power plants that burn 100% low sulfur coal (Trenton Channel) or fuel blends of 75% low sulfur coal and 25% high sulfur coal or 70% low sulfur coal, 15% high sulfur coal, and 15% petcoek (Monroe Power Plant). Ash samples are then subjected to hydrothermal conditions from 100-350 °C for 1-24 h at Los Alamos National Laboratory and leachate concentrations are measured by inductively coupled plasma-mass spectroscopy (ICP-MS) and compared to hydrofluoric acid digestion results. Experiments designed to aid in ligand selection and loading optimization show that di-(2-ethylhexyl)methanediphosphonic acid (H2DEH or DIPEX™) can be successfully loaded to a commercially available swellable organically modified silica (SOMS) media. Preliminary results show that DIPEX-associated SOMS surface loading can exceed 4x on a mass/mass basis and in simplified sorption experiments with Nd solutions (~pH 2), the DIPEX-SOMS media can sorb >90 mg Nd per g of media. Recovery of the sorbed Nd with low pH solutions has had low efficiency with the high (4 g DIPEX/ g dry media); however, near complete recovery was achieved with lower surface loadings (0.05 g DIPEX/ g dry media). Column experiments are being conducted to evaluate the optimal ligand/media ratio for repeated use. Completive sorption with Fe and other major cations are also being evaluated.

Jan 1, 2019

By Dan Norrgran

In recent years, a great deal of attention has been focused on developing mill liners to increase wear resistance, improve grinding efficiency and reduce energy consumption in milling applications. The installation of an appropriate mill liner is critical as it affects the overall cost and product quality. A mill liner has two specific functions. The first is to protect the mill shell and mill ends from direct contact with the abrasive grinding media (in this case, the liner serves as a wear surface). The second function is to transport the grinding media, creating energy for size reduction. The liner acts as a lifter, mechanically transporting and cascading the grinding media. The mill lining is a major cost in the milling operation. The costs associated with the mill lining include the capital cost of the lining, downtime required to replace the worn liner and the labor for installation. Generally, in hard rock mining, the life of a mill liner in secondary ball mills is 12 to 24 months.

Jan 1, 2009

By P. Bissert, M. Klein, L. Yan, D. Yantek

"Mine Safety and Health Administration (MSHA) regulations require underground coal mines to use refuge alternatives (RAs) to provide a breathable air environment for 96 hrs. One of the main concerns with the use of mobile RAs is the heat and humidity buildup inside an RA. The accumulation of heat and humidity can result in miners suffering heat stress or even death. MSHA regulations require that the apparent temperature in a fully occupied RA must not exceed 95°F. To investigate this issue, the National Institute for Occupational Safety and Health (NIOSH) conducted testing on a 23-person tent-type RA in its Experimental Mine (EM) in a test area that was isolated from the mine ventilation system. The test results showed that the average measured air temperature within the RA increased by 9.4°C (17°F) and the relative humidity (RH) approached 94 %RH. The test results were used to benchmark a thermal simulation model of the tested RA. The validated thermal simulation model predicted the average air temperature inside the RA at the end of 96 hours to within 0.6°C (1.0°F) of the average measured air temperature. INTRODUCTION If an accident occurs in an underground coal mine, miners who fail to escape from the mine can enter an RA for protection from adverse conditions, such as high carbon monoxide levels. One of the main concerns with the use of mobile RAs is the potentially adverse thermal environment inside an RA from the metabolic heat of the occupants and the heat released by the carbon dioxide (CO2) scrubbing system. Moreover, the humidity within the RA will increase through occupants’ respiration and perspiration and from the chemical reaction within the CO2 scrubbing system. The accumulation of heat and humidity can result in miners suffering heat stress, heat stroke, or even death. In its 2007 report to Congress, the National Institute for Occupational Safety and Health (NIOSH) Office of Mine Safety and Health Research (OMSHR) recommended that RAs should be designed to ensure that the internal apparent temperature (a temperature-humidity metric) in an occupied RA does not exceed 35°C (95°F). However, a standard method to determine compliance with this metric does not exist. The heat transfer process within and surrounding an RA is very complex, and is not easily defined analytically or experimentally. To investigate the related issues, OMSHR conducted heat and humidity testing on a 23-person tent-type RA in its Experimental Mine (EM) in a test area that was isolated from the mine ventilation system. During the testing, numerous parameters were measured: heat input to the chamber, the air temperature and relative humidity inside the RA, the air temperature in the mine, the mine strata temperatures versus depth, and the airflow inside and outside the chamber. The focus of this paper is on the temperature rise within an RA. TAITherm heat transfer analysis software was used to develop a thermal simulation model of the RA as it was tested in the mine, using the test results as the benchmark. Both sensible and latent heat were used in the test and the model."

Jan 1, 2016

By L. Widdifield, R. Riggle

"In today’s challenging mining environment the “Big Picture” (Caterpillar, 2013) approach to mining is often neglected. With haulage costs approaching up to 45 % of the overall mining costs, all too often the load-haul-dump- return cycle is not investigated in its completeness. This paper will discuss the aspects of taking the time to observe an operation from the “Big Picture” approach. In today’s mining business miners, engineers, trainers, supervisors, and managers have ever increasing roles and responsibilities as never seen before in the past decade. The endless human resource, safety, environmental, cost control issues and performance initiatives, detracts from precious time that may have been dedicated to examining the day to day operation. Having examined numerous mining operations over the past several years, one common denominator is lack of time to properly observe operating practices in the field and recognize both positive and negative observations. The old fashioned vocation of observing the operation to assess the haulage, loading and maintenance processes to adjust, maximize or enhance operations have sometimes vanished. Four areas to be discussed in this paper: (1) Look at the “Big Picture”(Caterpillar, 2013), (2) Use common sense, (3) Areas identified for biggest improvements in the operations, (4) Observation of small details for big impacts to lower cost per ton and increased production. The objective of this paper is to provide low cost recommendations to lower cost per ton and increase production. INTRODUCTION Whether miners claim to have been around and experienced it all or the “rookie” on the mine site, miners are expected to execute the mine plan at the lowest cost possible. So why is it so difficult to execute this task? Shouldn’t supervisors just have to man the equipment, tell operators to have a safe day and tally up the numbers at the end of the shift? And let the technology system do the rest? So what could go wrong? Lots. Mining companies seek help from consultants, training departments, performance reporting systems and an arsenal of resources. Armed with all this information, the supervisors just hop in the pick-up and tell the shovel operator to speed up. Sounds simple enough. When the improvements don’t happen, what could have gone wrong? It comes down to people, the simple things that were not executed over the months previously and as a result today the mines performance is not where it should be. A mine is built by people. Managers who have the vision to develop the ore body in a manner that follows sound engineering practices. The infrastructure to mill the ore and support the equipment needed to move the material. Along the way equipment is procured and operators trained to run the gear. Engineers and geologists set up the design, the material movement, and haulage routes. Sounds easy to this point. So, why mine after mine is there this constant struggle to move more with less and get the costs down? Understanding how to make “Great Miners” out of these people is critical to lowering your cost per ton."

Jan 1, 2016

By D. R. Taylor

Treatment of bentonite clay with mineral acids yields a modified clay product of high surface area and acidity which exhibits enhanced adsorptive and catalytic properties. A highly specialized segment of the clay industry based on this process has evolved into worldwide business with a capacity of about one-half million tons/yr. This paper will present data on the chemistry, mining, manufacturing and applications for acid- activated clays.

Jan 1, 1986

By Anil Kumar

In underground mine production units that employ discrete-vehicle face haulage, feeders are used in the belt network so that vehicles can unload rapidly without transmitting to the conveyor network the high material flow rates that result from rapid unloading. They prevent production bottlenecks at the face, while reducing capacity requirements for downstream materials handling equipment. Similarly, surge bins may be installed at intermediate locations in the network to smooth flows from a number of upstream sources, thereby reducing downstream belt capacity requirements. This paper introduces new stochastic process models to temporally describe loading patterns from unit operations and techniques for computing the probability of various fill levels for the feeder or surge bin. These results may be used to analyze the effect of alternative bin or feeder capacities and discharge rates on the performance and costs of the materials handling system.

Jan 1, 1994

By Alexander N. Winchell

"Location: The Menominee district has been described geologically in several units, because the known iron-bearing formations of the larger region are not a really connected. From the commercial and mining standpoint, however, the district em¬braces, all that territory extending from a point about five miles east of Vulcan to a point a few miles west of Iron River, an east-west distance of about fifty miles, and from a line about two miles south of Vulcan to one ten miles north of Crystal Falls, a north-south distance of about thirty-five miles. This area is largely in the State of Michigan, but includes more than two hundred square miles in Florence County, Wisconsin. The chief towns of the district are Vulcan, Iron Mountain, Iron River, and Crystal Falls, in Michigan, and . Florence in Wisconsin. The Wisconsin portion of the district has not produced a large portion of the output of the area.History: The earliest reports of iron ore in the Menominee district were made by J. W. Foster and S. W. Hill, who conducted a geological exploration from Lake Superior to Green Bay in the fall of 1848. It is a remarkable fact that in spite of their plain statements regarding their discoveries, these state¬ments were apparently forgotten for a period of nearly twenty years. Foster states that ""about two miles southeast of the lower falls (of the Twin Falls on the Menominee River) near Sec. 30, T. 40 N., R. 30 W. there is a large bed of specular iron ore associated with the talcose and argillaceous slates. It makes its appearance on the north side of the Lake and can be traced a mile and a half in length and in places is exposed one hundred feet in width."""

Jan 1, 1920

By Martín A. Encinas-Romero, GUILLERMO TIBURCIO-MUNIVE, María M. Salazar-Campoy, Patricia Guerrero-Germán, José R. Parga-Torres, Luis S. Quiróz-Castillo, JESÚS L. VALENZUELA-GARCÍA

Pressure oxidation is a hydrometallurgical oxidative pretreatment for refractory ores, such as sulfide ores. Here, simultaneous alkaline pressure oxidation and sodium cyanide leaching treatments were carried out on a pyritic ore from the Mulatos Mine located in Sahuaripa, Sonora, Mexico. Mineral characterization, agitation leaching, hot cyanidation under atmospheric pressure conditions, simultaneous moderated pressure oxidation and leaching, and kinetic testing results are shown. The modified variables were temperature, pressure, and cyanide concentration. Characterization indicated that pyrite was the main mineral. Simultaneous pressure oxidation and leaching experiments were conducted at a temperature range of 40–80 °C, oxygen pressure of 87.5–200 psi, and cyanide concentration of 0.8–1.2 wt% in a 2-L Parr pressure reactor. A dissolution rate of 81–86% was achieved under the following conditions: 87.5 psi, 80 °C, 0.8 wt% NaCN, for 1 h.

May 7, 2020

By B. Kraus

Many of us who have interacted with senior executives from leading oil and gas companies over the last few years on the subject of HSE performance have observed a marked shift in their engagement on this aspect of their business performance. There seems to be a shared impression that HSE performance will have markedly increased impact on their businesses going forward. On the back of this very real concern, many are taking material actions to secure a step change in their safety and environmental performance: hiring respected mainstream operational personnel to lead their HSE function; investing in capacity/skills development for HSE professionals to increase their effectiveness in addressing the needs of the business; taking a hard look at the efficacy of established management and audit programs (too much paper, not enough results?); investing in information management systems so they can have access to real time reliable performance indicators; and, critically, initiatives to reduce accident statistics (especially focused on fatalities and contractors? activities) and deliver meaningful reductions in their environmental footprints. Underpinning all of these actions is a clear sense that substantial, very well-intentioned activity and investment in HSE aspects of the business has not been hitting the mark and yielding too little return in terms of performance improvement. The very serious recent events on the US Gulf Coast and at a refinery in the US Pacific Northwest have added fuel to this fire. The need for approaches which will secure a step-change in performance on the front line in the global oil and gas industry has never been greater.

Jan 1, 2011

By James M. Barker

No commodity agreements now exist for sulfur and a lack of reference to sulfur commodity agreements exists in the literature. Law (1975) made a passing reference to sulfur as one of a group of commodities where "there have been additional control efforts of various types." Clearly, sulfur was a candidate, at least conceptually in the past, for some form of commodity agreement and the following discussion centers on the world sulfur market of the early 1980's in this context. GENERAL THEORY OF COMMODITY AGREEMENTS The upsurge in demands for commodity agreements seen in the last decade or so stems largely from agitation by the less developed countries (LDC) for better economic treatment by more developed countries (MDC). Several economic factors, real or imagined, adversely affect the LDC's as follows (MacAvoy, 1977): 1) variable demand in MDC's causes wide fluctuations in commodity prices which hurt the economies of commodity producers, who are often LDC's although consumer economies may also benefit from more predictable prices; 2) a general decline of commodity prices relative to the price of manufactured goods which hurts commodity producers in their balance of trade while their stocks and overcapacity rise; 3) instability of LDC economies enhanced by the above factors lowers internal stability, inhibits foreign investment, and retards economic growth; and 4) a lack of self respect when dealing with developed countries o, following the OPEC lead, LDC producers want the stature related to cartel market power.

Jan 1, 1985

By A. G. Provost

On April 3, 1981, Harrison Western Corporation was awarded a contract by Amax Alloy - A Division of Amax Inc., to sink the Henderson #5 ventilation shaft. The project was located on the Henderson Mine site 88 kilometers west of Denver near the town of Empire, Colorado (Figure I). The Henderson No. 5 Shaft, located in an Alpine environment at an elevation of 3145 meters, was a 9.8 meter diameter concrete lined shaft with a total depth of 793 meters. Work started and continued with Harrison Western employees until January 15, 1982. At that time, Amax made the decision to continue the shaft-sinking with their own labor, and with Harrison Western providing supervision under a management service contract. Shaft sinking continued under this arrangement to October 1, 1982, at which time Amax put the Henderson No. 5 project on standby status until further notice.

Jan 1, 1986

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 D. C. Seidel

The role of surface charge in soluble salt flotation, which was developed in Part 1, is extended to relate the theory to the specific phenomena of KCI- NaCl separations. Temperature-collector solubility relationships, metal ion activation, and particle size effects are discussed.

Jan 1, 1967

By QUANWEN PU, Yonggang Wei, Bo Li

With the advancement of industrial science and technology, more and more catalysts are used. The spent catalysts produced are solid waste products, which cause environmental pollution if they are not treated. At the same time, the spent catalysts contain some precious metals such as platinum in concentrations that are often higher than in their ore resources. Therefore, the recovery of valuable metals in spent catalysts is a hot research topic at present. However, due to the complex structure of the spent catalysts, dealing with them is a lengthy process. The first step of recovery, enrichment of the spent catalyst, becomes particularly important. In this paper, a pressure solution method is investigated for this purpose, in which the alumina carrier is dissolved and platinum is enriched in the leaching residue.

By H. W. Hintze

Coal handling facilities, such as utility plants, coal terminals, ports, manufacturing, processing, etc. Protect themselves against interruptions in coal receipts by maintaining a 60 to 90 day supply in storage. Not too long ago, these storage piles were referred in terms of hundreds or thousands of tons. Today, it is not unusual to have hundreds of thousands or millions of tons in storage. Burn, or shipping and receiving, rates have increased dramatically and storage piles have grown in horizontal as well as vertical dimensions. Fixed systems for delivering and retrieving coal from storage have increased in length and operating capacity and have become highly sophisticated in their operation. With few exceptions, mobile material handling equipment is used to handle all coal beyond the reach of these systems. These machines take excess loose coal from the fixed system to the storage area, place it on the storage pile, compact it, maintain the pile, protect against spontaneous combustion, the spread of fires if they occur, and return the coal to the reclaim system as required, plus many of the small chores around the facility.

Jan 1, 1981

By S. S. Peng

A well designed mining plan is one which minimizes the cost and the mining induced problems and maximizes the recovery of the coal reserve. In order to minimize the negative effects on surface structures caused by ground subsidence process due to underground mining activities, two kinds of practices are commonly employed by the mine operators. One is the support techniques which leaves an area of coal un-mined or partially mined beneath the structure to be supported. The other is the protection techniques which protect the structure when it is subsiding with ground taking advantage of the ground subsidence process (Luo et al., 1992). In designing the supporting techniques, the only currently available method in the U.S. is the one stated in the Pennsylvania Underground Coal Mining Rules (1985). However; The size of the support area designed by this method will be excessively large resulting in wasteful use of coal reserve when the overburden depth is more than 350 ft. A more scientific method is proposed in this paper for de-signing the support area. This method is based on a large amount of subsidence data collected throughout a number of major U.S. coal fields and the authors' experience with monitoring and protecting surface structures undermined by longwall panels. It considers the critical deformation in-dices that a structure can tolerate, and depth and height of underground extraction. The support area designed by this new method will not only assure the safety of the structure to be supported but also maximize the extraction of the coal reserve.

Jan 1, 1993

By L. Yuan, A. Smith

In order to provide insights for the optimization of ventilation systems for U. S. underground coal mines facing both methane control and spontaneous combustion issues, a computational fluid dynamics (CFD) study was conducted to model the potential for spontaneous heating in longwall gob areas. A two longwall panel district using a bleeder ventilation system was simulated. The permeability and porosity profiles for the longwall gob were generated from a geotechnical model and were used as inputs for the CFD modeling. In this study the effect of methane emissions from the mined coal seam, including the longwall face and overlying rider seam reservoirs on the gob gas distribution was considered. The spontaneous heating is modeled as the low-temperature oxidation of coal in the gob using kinetic data obtained from previous laboratory-scale spontaneous combustion studies. Unsteady state simulations were conducted and the effects of the coal’s apparent activation energy and reaction surface area on the spontaneous heating process were also examined. Disclaimer: The findings and conclusions in this report are those of the authors and do not necessarily represent the views of the National Institute for Occupational Safety and Health.

Jan 1, 2007

By R. M. Powers

The Florida Institute of Phosphate Research (FIPR) has funded a four-year research project to develop a computer model 'which will predict the hydrologic impacts of phosphate mining on surface and groundwater systems. The core of the model is an analytical geographic information system (SPANS) which integrates EPA's Hydrology Simulation Program Fortran (HSPF) surface water model with the McDonald-Harbaugh groundwater model (MODFLOW). The hydrologic model conducts both event and continuous annual Simulations driven by variable precipitation and temperature data. The model is currently being calibrated and will be ready for distribution to the user community in mid-1991.

Jan 1, 1990

By T. Rockley, J. Brune

"The mining of tabular deposits accounts for a significant portion of modern production in both underground hard rock and especially, soft rock mining. There is a large discrepancy between the availability of tabular reserves and the amount of development of these deposits, particularly when the deposit has a dip of around 25-50 degrees. This project studied the technical and practical barriers to the mining of these deposits through modern and historical case studies. The primary technical barriers to the development of these deposits are material movement and roof support. The study of historical attempts overcome these barriers and why they failed allowed us to research the possibility of implementing modern technology on previously unsuccessful methods. By modifying some common mining methods, some of these deposits can be mined at only a marginal increase in cost and using readily available equipment. These modified mining methods could make previously underdeveloped deposits to become viable. INTRODUCTION Tabular deposits are defined as orebodies that extend at least hundreds of meters along two dimensions, and a substantially smaller amount along another [1]. Moderately bedded tabular deposits are mined less often than their more horizontal counterparts due to the technical issues they present. These issues often cause lower productivity, higher cost, and more frequent accidents. Moderate dip is a less well defined term; but in this case, it will refer to any deposit which has a dip of at least 20°. This paper will focus on deposits that dip around 25°-50° and are deep enough to require underground excavation methods. These deposits are too steep for most conventional methods yet not steep enough for gravity fed methods to work efficiently. In some cases, this dip range is also referred to as intermediate or steeply dipping. The types of deposits most likely to fall into this category are sedimentary bedded deposits such as coal, trona, evaporates, placers, and other alluvial deposits. Some other types of deposits can fall into this category as well. These include some of the metal reefs such as the Bushveld Complex in South Africa, which was deposited by lava flows, but is tabular. Some areas have dips that fall into the moderately inclined category. There are also some metamorphic deposits such as slate or marble that can have dips of more than 20°. The dip angle of these deposits can cause several challenges. Ore movement becomes more difficult as the exceeds the limits of conventional conveyors, rubber-tired, or tracked vehicles. At the same time the dip is below the angle of repose of the material. This prevents gravity assisted haulage, as the ore and waste will not run downhill by itself. Another common problem in moderately inclined underground mines is roof support. The dip angle can increase the risk of pillar and support failure. This is due to slippage between rock layers, non-perpendicular support of the vertical stresses, and slippage of standing supports. The inclination leads to stresses that are not usually found in typical horizontally bedded deposits. These stresses may require larger pillars that may reduce ore recovery below profitable levels."

Jan 1, 2017