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By M. A. Georgiana

The Emerald Mine No. 1, located in southwestern Pennsylvania is presently owned and operated by Cyprus Minerals of Englewood, Colorado. High volatile bituminous coal is produced from the Pittsburgh No. 8 seam by both longwall and continuous mining methods. The coal is then mechanically cleaned on site utilizing a combination of heavy media separation and froth flotation methods prior to shipment to both the metallurgical and steam coal markets. The Emerald Mine is presently producing 2.8 million raw tons per year, while liberating approximately 6.5 million ft per day of methane. In light of the methane liberation rate, ventilation requirements have been significant and have always received utmost priority and consideration. Figure 1 shows the locations of the current and proposed shafts. Emerald utilizes two Joy (Model M120-58-880) axial vane fans on shafts No. 1, No. 2R, No. 3R. (one operational, one stand-by) The use of computer simulation of various ventilation networks was initially employed during the design stages (1975-1977) and has been utilized through the present. Obviously, the initial planning, under the ownership of Lykes Resources, was strictly theoretical. All the quantities were proposed and the resistances were based on prior simulations of other mines and mathematical formulas. However, once the mine was moderately developed, actual values were recorded and utilized. This procedure consists of: a) layout pressure and quantity points b) measure all air quantities where an air course splits

Jan 1, 1986

By J. L. Coburn

The Huari-Huari ore body is located in Southern Bolivia, at an elevation of approximately 3,800 meters above sea level. The ore is a complex massive sulfide, slightly marmatitic sphalerite, in a fault fissure filled hypo- thermal vein in Paleozoic shales and quartzite-altered sandstone. The sphalerite has common associations with pyrite and quartz and is frequently intricately intergrown with stannite, chalcopyrite, and pyrrhotite. The sphalerite also contains numerous inclusions of pyrite, marcasite, galena, boulangerite, jamesonite, quartz, arsenopyrite, and cassiterite. A research program was undertaken to develop a flowsheet for the recovery of separate silver, zinc, and tin concentrates by selective flotation. Based on this experimental work and subsequent flowsheet development, engineering and construction of a 500 metric ton per day concentrator was undertaken. This paper describes the process that was developed for the Huari-Huari ore and the unique aspects of the Huari-Huari concentrator.

Jan 1, 1977

By K. Rajamani

The word adapt means "to change so that one's behavior will conform to new or changed circumstances." Applying this definition to process controllers suggests that an adaptive controller can change its behavior in response to changes in the dynamics and disturbances of the process. In the minerals industry there are many control cases where adaptive control will provide superior control as compared with more traditional PID (proportional, integral, derivative) control. A typical plant uses as many as 100 to 200 control loops for lprocess regulation. Therefore, the task of initially tuning and then periodically retuning these controllers is a formidable problem, During the time the controllers are "un-tuned", product quality may deteriorate and unstable operations may result. Adaptive controllers are capable of tuning themselves, thus avoiding this problem. The computers commonly used in distributed control systems are easily capable of implementing adaptive controllers. In addition to the possibility of using the control computer to implement adaptive controllers, many distributed control systems will offer adaptive control as a standard feature in the near future.

Jan 1, 1984

By Vishnu S. Gupta

A modular computer program APEX (AMAX Process Evaluation Executive), has been developed at AMAX Extractive R&D, Golden, Colorado to facilitate rapid simulation of steady state material and energy balances of existing and/or proposed metallurgical process flowsheets. Currently, APEX is being used for the design, analysis, and evaluation of several of AMAX?s Nickel, Molybdenumand Tungsten processes. A unique feature of APEX is that it allows specifications of flow rates and compositions for different solid size fractions in addition to aqueous organic and gaseous phases. Thus, a metallurgical process which may involve crushing, grinding, flotation, leaching, washing, solvent extraction, precitation and refining operations can be simulated in a single computer run using APEX. APEX requires two input data files. The first is a process data file which includes physical and thermodynamic properties of the various chemical components of interest. This data file is unique to the process under study and does not require changes for alterations in the process flowsheet. The second data file is specific to a simulation case and includes descriptions of the flowsheet, various feed streams and the process equipment's operating conditions. In addition to temperature, pressure and percent solids, calculated information for each stream includes weight and volumetric flow rates, chemical compositions, specific gravities and enthalpies of solid, liquid and gas phases. For each process equipment in the flowsheet, APEX prints its operating conditions and detailed information about the streams that enter and leave the unit. Models of several general unit operations are preprogrammed in APEX. Also, the modular design of APEX permits quick and easy additions of simulation models which are specific to new and/or unique process operations. To study process stability and optimization, APEX permits several cases of a flow-sheet to be run together. Three simulations of the Moa Bay Nickel process have been excluded to illustrate the ease and flexibility of using the APEX system.

Jan 1, 1980

By S. M. Carpenter

In an ever increasing ?carbon? society; management and growth will be measured by one?s carbon footprint (or output). Industries, especially mining, are under an ever increasing scrutiny of carbon, water and environmental mandates. These mandates are measured by the emissions caused by the combustion of fossil fuels. The fundamental building-block for any business, strategic or management decision must be based on an understanding of one?s ?footprint?. The scrutiny is most stringent for the commodities producers, power producers & fuel suppliers in the energy market. An overview of currently acceptable standards, application of those standards and nuances experienced in collecting the data necessary to analyze and complete a company?s carbon footprint will be presented. A lack of regulation, the fear and expectation of new and ever constraining rules, regulation and a change in the federal administration is a recipe for uncertainty in the marketplace.

Jan 1, 2010

By J. Morris, R. Sellaro

El petrodiesel es un colector común para la flotación de carbón, pero la partición de compuestos orgánicos de diesel (DRO por sus siglas en inglés) en corrientes de proceso no ha sido ampliamente estudiada. Investigaciones preliminares sugieren que bajo esquemas de dosificación normales los contenidos residuales totales de DRO en aguas de procesos deben estar limitados a la fracción soluble en agua (WSF por sus siglas en inglés) sub-ppm. Es más, los hidrocarburos aromáticos poli-cíclicos (PAH por sus siglas en inglés) debería segmentarse de manera proporcional con los compuestos orgánicos de diesel (DRO). El propósito de este estudio fue confirmar estos resultados en pruebas de flotación realizadas en laboratorio. Se midieron los contenidos totales de DRO Y PAH en aguas asociadas con los flujos o corrientes de concentrados y relaves. Los resultados muestran que las aguas con concentrados tenían de manera consistente mayores cantidades de DRO que las aguas de relaves. Es más, los contenidos de DRO en ambos flujos generalmente se incrementaban con el aumento de la dosis de diesel. De acuerdo con la investigación preliminar, los DRO parecían estar limitados a la fracción soluble en agua (WSF) y los PAH tendían a segmentarse proporcionalmente con los DRO. Bajo condiciones de operación típicas, los DRO residuales no deberían representar una preocupación medioambiental, pero deben evitarse situaciones que permitan una sobredosis significativa de diesel.

Jan 1, 2014

By R. E. Doerr

The successful technical demonstration of coarse coal slurry transportation at Consolidation Coal Company's Loveridge Mine in West Virginia suggests that it is now appropriate to seriously consider this technology in other applications, especially the transport of ' coal in surface mining. Early examination indicates that coarse coal slurry transport may be highly competitive with existing haulage systems, depending on a number of factors. These factors are not yet completely defined, but certainly will include production rates, coal physical and chemical properties, terrain, soil conditions, climate, water availability and quality, availability of skilled labor and other economic considerations impacting the existing haulage systems.

Jan 1, 1983

By J. Drelich

The flotation limit of fine particles has been re-examined based on the effect of bubble size on contact angle, and a new surface chemistry-limited relationship describing the minimum particle size which can be floated is proposed. In this analysis the critical value of bubble-solid contact radius (re) for which there is no effective attachment between particle and bubble has to be determined. The values of re determined by extrapolation of our experimental data for contact angle versus bubble-solid contact diameter permit the prediction of the flotation limit of methylated quartz particles, with fraction-al coverage of trimethylsilyl groups from 0.07 to 0.51. The limit of fine particle flotation as determined by this theoretical approach agrees well with experimental data reported in the literature.

Jan 1, 1994

By K. H. Boss

In modern iron pelletizing plants fuel consumption has been optimized to such an extent that only minor savings can be expected in the future. Inspite of this fact, different process parameters were studied with a mathematical model and firing tests. The influence on fuel consumption and productivity was established. Furthermore, the adoption of simplified firing patterns was investigated, in particular for coal firing. In view of high costs of oil and natural gas, only substitution of these fuels by coal can substantially reduce production costs. In existing plants partial replacement of oil and gas can be achieved by addition of coal to the iron ore feed and by firing the pellets with pulverized coal. Two systems have been developed for the Lurgi- Dravo travelling grate process which enables coal to completely replace oil or gas. This paper describes in the first part the potentials for fuel savings available in the Lurgi-Dravo process. In the second part, different techniques for the use of coal as fuel in iron or pelletizing plants and in particular the recently developed Lurgi Multistage Coal Injection and Combustion Process (LMC) are discussed. Combined with the LMC process, a wide variety of iron ores and coals - also with high ash contents - can be used in the Lurgi-Dravo travelling grate process.

Jan 1, 1983

By Yoginder P. Chugh

Effects of moisture absorption on the behavior of the Dykersburg shale overlying Harrisburg coal seam in Southern Illinois are presented in this paper. Cylindrical samples of the shale 2.5 cm in diameter and 5.0 cm long were studied for weight gain and swelling strains at 90, 95, and 100 percent relative humidity and under immersed water conditions. After attaining equilibrium conditions, the samples were studied for changes in the strength and deformation behavior. The depth of moisture penetration was measured using the Vickers microhardness measurements. Using the basic mass transfer concepts, effective diffusion coefficients were computed for the shale.

Jan 1, 1980

By Christopher Mark

Six decades ago, the most dangerous job in the USA was mining coal underground. Roof falls were responsible for half of the deaths, killing about 100 miners every year. Fast forward to 2016 and zero roof fall fatalities. Just three miners were killed by roof falls during the following 6 years. How did the mining community achieve this historic goal? This paper starts by analyzing the roof fall fatalities in 1968, categorizing them by their fundamental cause. Then, it shows how each type of roof fall was reduced over time, using snapshots of the fatalities occurring in subsequent decades. Along the way, it evaluates the influence of the regulatory environment, changing mining methods, and better ground control technology. The study found that in 1968 more than half of roof fall fatalities at large mines were attributable to an inadequate safety culture. The immediate effect of the 1969 Coal Mine Health and Safety Act was to reduce the riskiest activities, like needlessly going under unsupported roof. Other hazards, like large roof falls, required technological developments before they were brought under control. Roof Control Plans, which the US Bureau of Mines had been advocating since the 1920s, played a significant role throughout the process.

Mar 12, 2024

By R. O. Y. Breese

Perlite is a hydrated acid volcanic glass that has been derived from the alteration of obsidians through incorporation of water into the silica structure. It is distinguished from other members of the water-bearing natural glass family by total water content, characteristic fracture and luster. The distribution of major occurrences worldwide is associated with silicic Tertiary through early-mid Quaternary volcanics related to plate movement. The No Agua dome and flow complex is one of the most highly studied perlite occurrences in the world. It clearly exhibits lithologic and textural zonations that reflect simple cooling history. Similar features are commonly observed within other perlitized, extrusive glass selvages. This paper briefly discusses current thought regarding geologic occurrence, the hydration process and the modes of origin with special emphasis on No Agua.

Jan 1, 1985

By David A. Campbell

There has been a long history of ironmaking on the North East coast of England centered around the River Tees. The industry developed here because of the availability of good coking coals to the North in Co. Durham, and the discovery in 1851 of ironstone in the nearby Cleveland Hills, South of the .River. Cleveland ironstone is relatively poor in quality, with an iron content not exceeding h% and high proportion of sulphur and phosphorous. The iron exists in chemical association with alumina and silica, and physical beneficiation processes involve a serious loss in iron unless the upgrading is limited, when the economics of the process become doubtful. Over the years, richer foreign ores have replaced the local ironstone, and the last operating mine was closed in 1964.

Jan 1, 1982

By Michael Murphy, Gamal Rashed, Brent Slaker

Pillar stability continues to be a significant concern in multiple-level mining conditions, particularly for deep mines when pillars are not stacked or the thickness of interburden between mining levels is thin. The National Institute for Occupational Safety and Health (NIOSH) is currently conducting research to investigate the stability of pillars in multiple-level limestone mines. In this study, FLAC3D models were created to investigate the effect of interburden thickness, the degree of pillar offset between mining levels, and in situ stress conditions on pillar stability at various depths of cover. The FLAC3D models were validated through in situ monitoring that was conducted at a multiple-level stone mine. The critical interburden thickness required to minimize the interaction between the mining levels on top-level pillar stability was explored, where the top level mine was developed first followed by the bottom level mine. The model results showed that there is an interaction between numerous factors that control the stability of pillars in multiple- level conditions. A combination of these factors may lead to various degrees of pillar instabilities. The highest degree of local pillar instability occurred when pillar overlap ranges between 10 and 70%. On the contrary, the highest degree of stability occurs when the pillars are stacked, the underlying assumption is that the interburden between mining levels is elastic (never fails). Generally, for depths of cover investigated in this study, the stability of top-level pillars shallower than 100 m (328 ft) or with interburden thicknesses greater than 1.33 times the roof span—16 m (52.4 ft) in this study—does not appear significantly impacted by pillar offset. The results of this study improve understanding of multiple-level interactions and advances the ultimate goal of reducing the risk of pillar instability in underground stone mines.

Jul 27, 2022

By A. F. Grandt

What is prime farmland? Can such land, once it has been strip-mined for coal, be restored so that it will produce corn, soybeans, wheat, and alfalfa? What methods or practices are necessary to bring about restoration within a reasonable time so that crop yields will be equivalent to or higher than those of unmined prime farmland under high levels of management? These questions concerned land use researchers in Illinois as early as 1948 when the Illinois Agricultural Experiment Station experimented with growing cultivated crops on strip-mined land in St. Clair County (1). This research was done almost 30 years before requirements of Public Law 95-87 were passed by the United States Congress and signed August 3, 1977.

Jan 1, 1980

By Nilufer Kursunoglu

Despite being crucial for meeting the world’s energy demands, coal mining operations present considerable health risks, especially when it comes to exposure to coal dust. Longwall coal mining, an advanced technique, has considerably enhanced production but made dust control more difficult. Due to its explosive nature, coal dust continues to be a serious and dangerous concern in the industry despite developments in safety technology. This study aims to comprehensively assess the risk of coal dust explosions by integrating fuzzy risk matrix and Pareto analysis methodologies, offering precise risk ratings for various root causes. A fuzzy risk matrix was developed to assign exact risk ratings to identified root causes. Additionally, a Pareto chart was used to identify the main reasons and suggest particular preventive measures. 17 significant causes were determined for underground coal mines based on the study’s methodology, and some preventive measures were suggested. In accordance with fuzzy risk rating values, root causes were divided into six categories. The root hazard with the highest risk rating was identified as ‘accumulation of inflammable gas/gases’. The proposed approach was used to examine incidents caused by coal dust explosions in Turkish coal mines in order to demonstrate the effectiveness of combining the fuzzy risk matrix and Pareto analysis for assessing coal dust explosions. This study gives not only a solid framework for risk assessment but also critical information for classifying the risks associated with coal mine dust explosions. The results highlight the critical necessity for proactive and preventive actions to reduce the hazards of coal dust explosions and protect the safety of mining workers.

Nov 16, 2023

By Wolfgang Pietsch

DR iron') is a generic term for metallized product that results from the direct or solid state reduction of iron ore. In direct reduction, iron oxides are reduced to metallic iron in the solid state without an intermediate melting step. MIDREX ® Iron is the DR iron material produced in the MIDREX ® Direct Reduction Process. Except for some thermal and mechanical degradation, the external physical form of as-reduced DR iron is the same as the feed material. Chemically, oxygen associated with iron is removed leaving a very porous structure. Figure 1 is the scanning electron micrograph (SEM) of the internal surface of a MIDREX Iron pellet obtained from a Swedish oxide pellet during reduction at 760 °C. Figure 2 is the SEM of a polished and etched cross-section through the same pellet showing the amount of intraparticle porosity. As a result of this high porosity, apparent density of DR iron is relatively low, typically a¬round 2 g/cm3, and specific surface is extremely high, typically around 1.0 m2/g or more. Both density and specific surface depend on the raw materi¬al and the operating conditions of the direct reduction plant. Normally, more than 97% of the available iron is reduced into metallic iron with the rest mainly in the form of wustite (FeO). During direct reduction, the gangue in the iron remains essentially unchanged. Removal of oxygen and the corre¬sponding reduction in weight result in a slightly higher percentage gangue in the product than in the raw material.

Jan 1, 1976

By William M. Warren

Recent sinkhole activity in carbonate terranes of Alabama has resulted in damage to transportation lines, structures, utility lines, and property in general. Active sinkhole development and subsidence has been well documented in Alabama, Florida, Pennsylvania, and South Africa. An excellent example of the potential danger resulting from this activity is the spectacular collapse under a South African gold ore crusher plant that resulted in the death of 29 men in 1962. Due to the severity of the problem in certain localized areas in Alabama, a detailed investigation is being undertaken by the Geological Survey of Alabama and the U. S. Geological Survey. One of the most promising techniques is the application of aerial photography and thermal infrared imagery. Conventional and modern remote-sensing techniques are being used in Alabama to locate and define areas of sinkhole activity and to determine which areas are most prone to its occurrence.

Jan 1, 1975

By Alan Rhodes

This study is initiated to investigate the efficiency of separation of mineral slimes using electroflotation as compared to that of column and conventional flotation techniques. Important parameters such as collector concentration, pH, current density, aeration rate, etc., have been studied. The results indicate that electroflotation can be used more efficiently in processing rutile slimes (10 µ) under certain operating conditions.

Jan 1, 1982

By R. Perez

The consumption of grinding media forms a significant part of the operating cost of a mineral processing plant. An estimated half billion pounds of steel in the USA and over one billion pounds in the world are consumed each year in wet grinding alone. However, there is some conjecture as to the interacting roles of abrasion and corrosion. In order to provide a more complete picture of the conjoint action of abrasion and corrosion, marked ball tests were conducted on different grinding ball compositions in a laboratory ball mill and the metal losses were measured on varying the conditions, i.e., pH, PO2, in wet grinding a Cu-Ni gabbroic rock and compared with taconite grinding. Ball wear rates ere discussed with respect to ball composition and microstructure and the varying conditions used in the grinding tests.

Jan 1, 1984