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By Karin Bäppler

Hydropower produces almost two-thirds of the world’s renewable electricity generation and delivers a major contribution on the ambition of the Paris Agreement and Sustainable Development Goals (SDG) with a range of benefits to society and environment. These include clean and flexible generation and storage in addition to reduced dependence on fossil fuels and avoidance of pollutants. The Limberg III PSP is one of the European projects that addresses the implementation of the UN SDGs. The challenge of the project is the construction of a 770 m long pressure shaft to be excavated with a TBM at an inclination of 42°.

Jun 13, 2023

By Mo Wanqiang

Equivalent-pressure ventilation is a method of balancing the air pressure between a productive face and its gob to extinguish fires and prevent the infiltration of toxic gases, so that the production of the face can be maintained. The method was successfully applied in Coal Mine No. 1 of Hebi Coal Mining Administration in north-central China. In this article, a practical application of the equivalent-pressure method to prevent carbon monoxide from entering an active longwall face adjacent to a fire breeding area is described, and four steps to achieve equivalent-pressure are discussed. The reliability of using this method and measures to maintain the equivalent-pressure are analyzed. It was observed that this method could maintain high production level while no sacrificing safety at the longwall face.

Jan 1, 1984

By Thon T. Gin

The lithologic, mineralogic, and magnetic beneficiation characteristics of the iron formation at U. S. Steel's Atlantic City Ore Mine, Fremont County, Wyoming, have been determined. The iron formation averages about 30 percent Fe content, and varies from 125 feet to about 500 feet in thickness. It is composed of interbedded magnetite-rich quartzites, magnetite-quartz-amphibole schists, and amphibole-chlorite schists. Quartz, actinolite-tremolite, chlorite, and magnetite are the essential mineral constituents. These rocks are differentiated into four major ore types on the basis of their relative quartz and amphibole content. The iron content of the magnetic concentrate decreases and the silica content increases with decreasing grain size and increasing amphibole content in each ore type at the same fineness of grind. Criteria were developed to enable the mine operator to recognize the ore types and to blend them to produce a more uniform concentrator feed. This results in less variation in product quality and requires fewer changes in operating conditions-in the concentrator.

Jan 1, 1965

Sinter mixes of three iron ore types were prepared with a range of water contents in a laboratory investigation. The mean diameter of the granulated mixes and the void fraction of beds of the mixes were determined experimentally. Pressure drop measurements over a range of flow rates were made in a laboratory permeameter with pressure tappings at several depths in the bed. The Ergun equation was applied to the results to determine the shape factor of the granulated mixes. The pressure readings down the bed were used to estimate the local void fraction in the bed using the Ergun equation and the calculated granule shape factors and it was found that there was a decrease in void fraction with depth in the bed. The significance of this and the variation of the shape factor values with the amount of water used for granulation is discussed in relation to the strength of granules of the sinter mixes.

Jan 1, 1984

By S. H. Amini, A. Noble

"While many classic mineral processing circuit design approaches rely on deterministic methods, numerous studies have shown that the uncertainty inherent to the various input parameters can significantly influence design decisions. In a separation circuit, many of the technical uncertainties can be mathematically represented as statistical distributions for the unit recovery and feed grade. These uncertainties are then propagated by the circuit design and reflected in the circuit performance indicators, such as product grade and global recovery. An effective design strategy entails identifying which units are most influential in this uncertainty propagation and thus merit further consideration. Unfortunately, few analytical tools provide this information, particularly those that rely solely on deterministic methods. However, one promising approach is through the application of Taguchi’s method, in a fashion similar to statistical tolerancing of manufactured products. Since the technical challenges are fundamentally similar, Taguchi’s method shows promise in evaluating the level of compounded uncertainty by various circuit designs while determining the role of each separation stage on the overall selectivity and variability of separation circuits. This paper demonstrates Taguchi’s method in several two and three unit circuit designs. INTRODUCTION AND METHOD DESCRIPTION Uncertainty in Mineral Processing Circuit Design Analysis and estimation of uncertainty propagation in mineral processing separation circuits is an essential and significant aspect of an optimal circuit design procedure. Most of the current circuit design methodologies have been constructed, implemented, and validated using a deterministic modeling approach. However, numerous studies have shown that the inherent uncertainty induced by uncertain design parameters can be a significant factor in many mineral processing applications (e.g. Kraslawski 1989; Xiao and Vien 2003; Ghaffari et al. 2012). Thus, an effective circuit design methodology must be able to quantify uncertainty in separation circuits with limited input data. This paper describes Taguchi’s method, as an experimental design technique, to approximate uncertainty in mineral processing applications, and then the similarity of results between Taguchi’s method and Monte Carlo Simulation is investigated. Monte Carlo Simulation The term “Monte Carlo Simulation” has been used to refer to a variety of stochastic simulation methods spanning a broad array of business, technical, and scientific domains. Most generally, Monte Carlo Simulation refers to numerical analysis which is based on (pseudo) random sampling from a domain of input parameters with a known statistical distribution. This methodology allows one to determine the distribution of expected results from a standard deterministic process model. Execution of a Monte Carlo simulation begins by identifying the domain of input parameters, statistical distributions for each parameter, and a deterministic process model which describes the anticipated result as a function of the inputs. Next, one discrete random sample is taken for each input parameter, considering the input distributions. The process model is then solved for this mix of input parameters, producing a single simulation result. This procedure is then repeated a “large” number of times, utilizing new randomly sampled input parameters for each simulation iteration. Once the desired number of iterations is reached, the results of each independent simulation are aggregated to produce descriptive statistics such as minimum, maximum, mean, standard deviation, kurtosis, and other distribution parameters. Given enough iterations, the Monte Carlo method fully explores potential synergies between the input parameters. The methodology does not require the process model to be differentiable, continuous, or even analytically defined. While the number of required iterations varies in relation to th"

Jan 1, 2017

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 Robin P. Gardner

The mechanistic approach to comminution consisting of incorporating particulate breakage functions into a suitable population balance equation has been developed by a number of researchers over the past decade or so. (1) To date this approach has been developed and demonstrated primarily for batch-operated, laboratory or small-scale ball mills. However, since industrial mills are mostly quite large and operated in the continuous mode; suitable population balance models and methods for obtaining the necessary breakage and other model parameters must be developed. This paper describes and investigates a radioisotope tracer technique for this purpose, Population balance models previously developed(2,3) are adapted for this study.

Jan 1, 1974

By W. S. Sanner

Experiments were conducted to determine the quantity and purity of ultraclean anthracite that could be prepared in the laboratory, using conventional separating techniques. A low-, a medium-, and a high-volatile anthracite were studied. Specific gravity separation followed by grinding, screening, and refloating at lighter specific gravities yielded small quantities of material purified to 1.0 percent ash, as follows: From low-volatile anthracite, 0.7 percent; from medium-volatile coal, 1.0 percent; and from high-volatile coal, 2.3 percent. The reduction in ash had no appreciable effect on the volatile matter or sulfur content of the coal. The limited quantities of material containing 1.0 percent or less ash obtainable indicate that if ultraclean coal is desired, a practical approach should include the processing units as an integral part of a conventional dense-media washing plant.

Jan 1, 1968

By Karl C. Dean

The current emphasis on environmental problems has focused attention on the massive nationwide accumulations of mine, mill, and smelter wastes that represent potential air and water pollution hazards. The pollution hazards can be reduced or eliminated by utilization or stabilization of these wastes. The U.S. Bureau of Mines, since the inception of the Solid Waste Disposal Act of 1965, has been conducting research to determine the practicality of various utilization and stabilization procedures. Investigations include partial extractions of desirable waste components and full utilization of the wastes as simulated soils or in ceramic or other structural products. Chemical, vegetative, and combined chemical-vegetative methods of stabilization have been actively studied. This report updates information previously developed by the Salt Lake City Metallurgy Research Center and presents the current status of antipollution solid waste work 1/,2/.

Jan 1, 1970

By D. Randall Crooke, Ron R. Jorgenson

Many coal combustion products (CCPs) have historically been unsuitable for placement as mine backfill because of their physical and geochemical properties and/or regulatory status. However, innovations in paste production and transport of CCPs utilizing the high, fine particle contents of these fine-grained waste materials and their water retention colloidal properties produce a non-segregating, self-cementing material that may be environmentally suitable for placement as mine backfill. Both industry and the regulatory agencies are enthused by the possible cost reductions, both in design and construction of disposal sites, and the reduced environmental impacts of CCP realized by implementation of this new use/disposal technology.

Jan 1, 2001

"Replacing the century old rail tunnels that run beneath the Hudson River and carry about 200,000 passengers per day between New York to New Jersey has been a high priority for many years. But after Superstorm Sandy hit the east coast of the United States in 2012, the urgency to replace the tunnels increased dramatically. The Hudson Tunnels project is one of nine projects that make up the larger $30 billion Gateway Project. The Gateway Project has been called the most urgent infrastructure program in the country and the Hudson Tunnels is the most critical part of the project, as it will build a new rail tunnel under the Hudson River and rebuild the existing and deteriorating North River Tunnel that connects New York and New Jersey.“Superstorm Sandy proved the level of resiliency of the tunnels, which was not very good,” Amtrak deputy chief engineer structures James Richter told attendees of the George A. Fox Conference in New York City on Jan. 23. Age and corrosive salts deposited by flood waters from the storm in 2012 have affected interior concrete and copper wiring in the tunnels. “Since then, things have been deteriorating and getting less reliable.”Richter, along with Mohammed Nasim, senior director engineering design, both with Amtrak, spoke at the 2018 George A. Fox Conference where more than 350 tunneling and underground construction professionals attended the conference at the Graduate Center of the City University if New York to share insights about the complexities many of them face on daily basis.Under the theme of “Managing construction of complex underground projects: Strategies for tunneling in populated areas,” the one-day conference featured presentations from some of the top minds in the tunneling and underground construction industry. The presentations touched on everything from the highly technical challenges of constructing tunnels through changing geology while working beneath cities and rivers, to navigating the complex financial issues and contracts that come with the projects that have many stakeholders.All of those challenges, and more are part of the Hudson Tunnels project. It is one of the best examples of the full complexities of a complex tunnel project, with the added pressure of securing funding from state and federal government entities under an increasingly tight deadline."

Jan 3, 2018

By M. Dayne Aldridge

A description is given of an experimental ventilation control system designed, built, and tested by WVU under United States Bureau of Mines sponsorship. A description is given of the control, system used and the mine-wide microcomputer-based ventilation monitoring system used with it. Test results of experiments conducted with this system at Eastern Associated Coal Corporation's Federal No. 2 underground coal mine are presented. In addition, a brief description is given of a new microprocessor based system presently being tested.

Jan 1, 1980

By L. W. Saperstein

P.J. Ehret By and large, I agree with many of the precepts discussed in the Saperstein paper. I believe there is much more that can be done on the local level to involve both government and planning in the mine permit review process. Admittedly, much can be done to improve discussion between the state regulatory authority, local authorities, and mine operators. However, I strongly disagree, as suggested in the paper's conclusion, that such a system, as outlined in Saperstein's paper, could result in a reduction of review time or a lowering in the cost of permitting. The implementation of such a system by its very nature would only add a new level of bureaucracy to an already cumbersome process. This system, in my opinion, would only add to the cost of permitting and the time necessary to obtain a permit. Admittedly, it would achieve the result of adding local influence into the permitting process, but at what off-setting cost? It has been my professional first-hand experience and observation in the permitting and lands unsuitable processes to note that under the present system, local governments that do feel they have a stake in local mines and actively ad¬vocate their position (not simply comment), have had significant input into the conduct of mining and reclamation plans in their areas. Mining companies that mine in these areas are aware of local interests and attitudes, and do consider them in their plans. Simply put, local governments that want to get involved and want to play significant roles can and do. Those that do not advocate a position or have no input to offer do not. Although the present system is not as direct in effect in regard to local control as Saperstein's, it does work. It does so without the red tape that would result from developing miniature regulatory authorities in every county in which mining occurs. Although local input is important, there are many more sections of the Surface Mining Control and Reclamation Act (SMCRA) than Sections 508(a)(8) and 522(a)(3)(A) that also are important. It appears Saperstein's paper may overindulge these sections. An additional specific comment is made in regard to the statement that while local areas benefit from mining (wages, salaries, and purchases), they also endure environmental deterioration caused by mining affects. It is believed that the whole purpose for which SMCRA and its resulting regulations were enacted and developed was so mining would not be permitted if significant environmental deterioration could occur. Therefore, it could be argued that this point under current law is moot. Reply by L.W. Saperstein P.J. Ehret writes in a reasoned and rational way and makes some good points. The arguments in favor of central control of the designation process reflect all of the benefits associated with central environmental control: consistency of enforcement, efficiency of operation, ease of communication among enforcing agency, etc. Nonetheless, the decision to mine or not to mine is a landuse decision which, in substance, is similar to the decision to build a shopping mall, a new highway, or a housing subdivision. Although, state and federal governments' interests in the protection of public welfare are real and are expressed properly in mining laws and mining enforcement agencies (OSM, Illinois Department of Mines and Minerals, etc). I continue to maintain that the permitting and designation processes should originate with local government, which is in keeping with the American tradition of delegation of the land-use decision to local or regional government.

Jan 4, 1984

By Y. H. Zhan

In beneficiation of phosphate ores it is common to use screening to produce the coarse "pebble" concentrate, and flotation to process the -1+0.1 mm size fraction. The -0.1 mm desliming product is treated as tailings. A new partially hydrophobic flocculant, P(MAAA) latex was developed to enhance flotation recovery of fine apatite particles through selective flocculation.

Jan 1, 2002

By Sukumar Bandopadhyay

In recent years, research in the field of artificial intelligence (AI) has had many important successes. Among the most significant of these has been the development of powerful new computer software known as the "expert systems". Expert system programs designed to provide expert-level consultative advice in mineral exploration (Duda et al, 1981), scientific (Feigenbaum, Buchanan and Lederburg, 1971) and medical (Shortliffe, 1976) problem solving are generally acknowledged to be among the forerunners of this research. As the decision makers virtually in all fields face a more complex and involved world within which to operate, the need for some decision support is also becoming urgent. Thus applications of expert systems continue to spread out reaching problems that, because of their dimensions or particular aspects, set more demand on the decision methodologies. To meet these new requirements, many activities which were performed in the past by the domain expert or engineer must become automated. Furthermore, previous research (Dawes and Corrigan, 1974; Dawes, 1979) has shown that automating an expert's decision rules often provide better decision than the expert does. For large systems it would be very useful (or even necessary) to have formal tools, allowing one for example, to automatically discover inconsistencies, contradictions or redundancies, or to identify the possibilities of wrong lines of reasoning in the decision process.

Jan 1, 1990

By Robert Moore Lewis

A unit for separating minerals into two prescribed size fractions, designated as a Lewis Hydrosizer, was developed at the North Carolina State University Minerals Research Laboratory. Ore samples with different mineral compositions, including coal, were separated effectively with the laboratory continuous unit. Commercial size units are in operation in North Carolina and Mexico, and under construction in Norway. Additional units are being build or are in the planning stage at several companies.

Jan 1, 1983

By John D. Morgan

The U.S. economy annually needs over 4 billion tons of new mineral supplies. The value of domestically produced energy and processed materials of mineral origin exceeds $175 billion annually, but domestic production of both raw and processed minerals is not keeping pace with demand.

Jan 1, 1974

By Kostas Fytas, Pierre Bousquet, Bill Evanelou

Acid mine drainage (AMD) is a serious environmental problem that preoccupies the Canadian Mining Industry. Considerable amounts of money are spent every year in an effort to prevent or reduce the acid mine drainage phenomenon. AMD occurs when sulphide minerals (ex. pyrite) contained in rock are exposed to air and water and subsequently oxidise to produce low pH water. This acid effluent has the potential to mobilise any heavy metals contained in the rock. Coating the sulphide minerals with silicates is a new promising technology to reduce AMD. Pynte is treated with a solution containing H2O2, sodium silicate and a buffering agent. H2O2 oxidises a small part of pyrite producing ferric iron (Fe3+) ions. These ions subsequently react with the silicate ions to produce ferric hydroxide-silica that precipitates on the pyrite surface producing a passive coating. This silicate coating can protect the grains of pyrite from oxidation. This paper presents a series of experiments that confirm that silicate coating can considerably reduce AMD.

Jan 1, 2000

By W. A. Haley

Wheel loaders became important bulk materials handling tools in the early fifties. As they grew in stature, productivity, reliability, and acceptance, the demand for larger, more rugged machines evolved. In the early sixties, the introduction of a 6-yard model by a major equipment manufacturer led quickly to widespread experimenting and rapid worldwide acceptance in loading blasted rock in stone quarries and smaller metal mines. As the wheel loaders grew in popularity for shot rock loading, larger models, 12- to 15-yard size were developed and saw widespread use by 1970. In the past 20 years, at most quarries and small to medium size mines, most cable operated power shovels have been replaced by large wheel loaders and more recently, hydraulic excavators as the primary loading tool. Wheel loaders larger than the 15-yard class are not used widely. Until about 1970, very few overburden haulage trucks were used in domestic coal mines. About that time, many states started enforcing stringent mine relcamation regulations and in 1977, even more stringent federal legislation was passed. These controls brought about drastic changes in coal surface mining methods in the mountainous areas of Appalachia, in smaller midwestern mines and in the large mines of the western states. Basically, simple material casting methods were replaced at most eastern mines by "haul-back" and "mountain top mining" methods using controlled placement of overburden as it is removed from the coal. These methods dictated much more extensive use of loaders/ shovels and trucks to the point that most coal mining in those areas is now by loader/shovel trucks methods. And those areas have become the home of the country's largest population of large wheel loaders and trucks in the 35- to 85-ton size class with a trend to even larger trucks and shovels. To maintain equal production or provide for growth, the new methods have caused a sharp increase in machine intensity to the extent that at some mines, up to three times as many machines were required to mine a million tons of coal in the late seventies as compared to the machine needs in the sixties. Mining costs and coal prices also took a big jump in the mid-seventies, paralleling the drastic price increases in oil and other forms of energy.

Jan 1, 1984

By L. B. Phelps

Current mining regulations require revegetation in reclaiming surface nines. Excessive soil compaction can be an impediment to successful revegetation in poor soil conditions common to Eastern coal nine sites. A field study was performed to determine the bulk densities of soils that had been spread by either bulldozers or scrapers at a strip nine site. Moisture-density relationships for the soils were determined from the field samples. These were compared with stockpile samples compacted by the Standard Proctor compaction test. The results of the study indicate that the degree of compaction could be lessened through proper soil handling procedures.

Jan 1, 1986