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By Allan M. Johnson

The Sherwood Mine is being monitored to determine the nature and extent of changes in the mine and its environs which result from the closing and the cessation of pumping. Of particular interest was the possibility of piping-induced subsidence occurring as the mine flooded. Previous experience in the district indicated that this possibility was very real. A monitoring system, including acoustic sensors, extensometers, surface subsidence monuments, and ground water observation wells was installed in July 1978, just prior to the mine closing. Late in 1979, three piping-induced subsidence events occurred. The monitored data, and related laboratory studies are being applied to a quantitative description of piping-induced subsidence.

Jan 1, 1980

By William C. Grady

The environmental and economic problem created by pyrite in coal are well documented. The removal of pyritic sulfur prior to, or during, utilization has been the object of considerable research, however, much of this research has proceeded without a proper knowledge of the microscopic occurrences of pyrite in coal. This paper investigates the forms, occurrences, and variations in the distribution of pyrite in major West Virginia coal scan. Twenty-nine samples from twenty-two major west Virginia coal scans were selected for this study (see Table I). The samples were selected so as to be representative of the major coal producing areas of the state. All samples, except five, were collected at active surface mines, as indicated in Table I, and all except one were channel samples. The time interval between sampling and preparation of polished microblocks varied from two months to two years, though most were prepared within three months of collection. Grinding, screen¬ing, and riffling of samples to obtain 250 grams of -20 mesh coal for microscopic analysis strictly followed ASTM procedure D2013-72.

Jan 1, 1976

By David A. Summers

Historically, the presence of methane has been a problem, mainly in and around the working areas of active coal mines, and only in these area has drainage been considered. Drainage, where practical, has been achieved through the drilling of holes forward into the coal and the surrounding strata from the working area. These holes generally have been short in length, although where methane drain- age operations around a longwall face have been undertaken, the holes have had to be longer in order to adequately drain from the center of the face into the access gate roads. In recent years, attempts have been made to degasify the coal seams in advance of mining, without disruption of the mining cycle. This is done by drilling much longer horizontal holes through the coal in advance of the working area. Under the aegis of the Federal Government, methods have also been developed for draining seams of coal of their methane content in advance of mining, but from shafts sunk from the surface, without using the active area of the mine as the location for the drill holes.

Jan 1, 1979

By John Lovering

The Afton property is located 180 air miles East-Northeast of Vancouver and nine miles West of Kamloops, a city of 60,000 people, in South Central British Columbia, Canada. The mine is adjacent to the Trans-Canada Highway at an elevation of 2,200 feet above sea level. The orebody is a porphyry, copper deposit that has undergone supergene alteration. The-major economic minerals in the supergene zone are native copper and chalcocite with chalcopyrite and bornite in the hypergene areas. The grade is one percent with an overall copper distribution: 70% native, 25% chalcocite and 5% chalcopyrite with bornite and covellite. The ore also contains important, but variable amounts of gold and silver.

Jan 1, 1985

By Douglas Ball

An underground storage field is a gas field where man, not nature, has put all or most of the gas. All but one of those in use today are in the pore spaces or "porosity" of sedimentary rocks, the most common being sandstone. The one exception, near Newcastle, England, is a gas storage in a cavern dissolved from rock salt. The tens of millions of barrels of LPG (liguified petroleum gas) now stored in salt caverns mined in shale is liquid storage, not gas storage, and in this paper I recognize the presence of these installations but do not include them in the gas storage category, Since, with the English exception, gas storages are gas fields, they can all be sorted into the categories used to describe gas fields, 95% of them once gas fields anyway, but some of the remaining 5% are the ones having the greatest effects on underground waters.

Jan 1, 1960

By C. C. Hatch

As part of a general project to simulate a concentrator, the Brenda Mines Limited secondary crushing plant, located near Peachland, B. C., was sampled during the summer and winter of 1975 to develop a digital crushing plant simulator specific to the Brenda operation. The purpose of this simulator was to study the influence of manipulable process variables on important responses and to permit study of alternative circuit configurations if desired. This paper describes the simulation methodology employed and presents the results of a computer study of the secondary crushing plant (1).

Jan 1, 1979

By E. M. Haynsworth

The disposal of phosphatic clays has presented a problem to the phosphate industry since the mining of phosphate rock first began. As the flotation process was introduced in the late 1920's, the problem of clay disposal was increased significantly since clay is present in proportionally greater quantities in reserves yielding flotation concentrates. Because of their physical character and the tremendous surface area per unit volume, these clays have the characteristic of retaining large volumes of water as they are slurried during processing. The phosphatic clays with which we are dealing consist primarily of apatite, wavellite and montmorillonite. In the beneficiation process, we remove the -150 mesh material as waste. However, the particles are essentially smaller than -325 mesh, and more than 70% are smaller than three microns. The disposal of clay and the recovery of a portion of the water require settling areas with a capacity ranging up to 2 cubic feet for each cubic foot of phosphate matrix mined. According to a recent study by the Bureau of Mines, the average cost for disposal of these wastes is 24.5 cents per ton of, product (U. S. Bureau of Mines Circular 8404). This is a major cost of phosphate rock production.

Jan 1, 1970

By C. B. Daellenbach

The influence of reduction roasting and thermal shock on the grindability of a refractory low-grade Michigan iron ore was examined in bench scale tests. The quantitative effects of the various treatments were evaluated at three sieve levels: 48, 100, and 400 mesh, using ball mill grindability and work index parameters as response indicators. Data from the testing program were analyzed statistically as a means of isolating the effects of cooling rate, roasting temperature, and ore chemical condition. All three variables were found to have an important influence on the grindability of the treated ore; ore chemical condition and roasting temperature had the most pronounced effects.

Jan 1, 1970

By S. P. Girrens

A coupled finite element geomechanical- hydrology code is currently under development for application to the problem of predicting groundwater disturbances associated with mine subsidence. The structural-fluid coupling is addressed by calculating the subsided mine geometry, with emphasis placed on determining the strata disturbance and locating damaged regions, for input into a hydrology code, which determines localized volume flow rates and aquifer fluctuations. Benefits from coupling will be best realized when field measurements, an additional aspect of the study concurrent with analytical investigations, indicating the relationship between increasing rock strain and increasing permeability are incorporated into hydraulic material descriptions. Hydrologic and struc- tural calculations are presented to demonstrate computational capabilities applicable to mine subsidence

Jan 1, 1982

By R. R. Odman

The Malmberget Division of LKAB is located 70 km north of the arctic circle and has about 2000 employees. The dominating products are sinter feed concentrate and pellets. A general flow sheet for the operation is shown in Figure 1. About 20 percent of the ore body consists of hematite, which is mined separately and processed into sinter feed concentrate. That pert of the ore consisting of magnetite passes through a dry cobbing plant. The robbing process includes crushing, screening and dry magnetic separation. The entire cobbing product is used as feed for the wet concentrator. After rod mill grinding and magnetic separation the concentrated slurry is classified. The coarse fraction (+200 mesh) becomes sinter feed concentrate and the slime fraction after further ball mill grinding and magnetic separation, becomes pelletizing feed. A small quantity of the magnetite ore is processed into special iron-rich products in the the wet concentrator. Two types of pelletizing plant are used, shaft furnace and straight grate. This paper will deal only with experience gained at the straight grate plant.

Jan 1, 1979

By Duk-Won Park

Ground water has been a problem in underground mines (Anon., 1981; Aughenbough, 1973; Stansbury, 1981). Water migrates from water-bearing formations and surface water bodies such as lakes, ponds or creeks into the underground workings through fractures and cracks. As a result, under- ground workings become plagued with the necessity of having the water pumped out in large quantities. Underground workings become flooded when unexpected amounts of water flow into the openings, especially when mines use pillar extraction or longwall mining methods. It is difficult to detect water bodies above the coal mine roof before water problems take place. The resistivity method was used as a method for detecting water saturated rock layers and bodies of water above the roof of a coal mine in northern West Virginia, where the multiple seam mining method was being used.

Jan 1, 1983

By Wendell H. Nielson

Flotation processes contain disturbances which make material balance closures difficult to achieve. Lack of closure also arises from instrument errors. A portion of these problems can be overcome by proper equipment selection; the primary measurement installation and methods of initial data filtering are discussed below. The problem of data adjustment has been considered before (2). The technique described here is essentially that of Ripps (2). The technique was expanded to include linearization of non-linear material balance equations. An additional large error detection portion was also added to Ripp's formulation. Ripp's technique is based on a Lagrange-Multiplier optimization method. The Lagrange-Multiplier technique is generally applied when there are equality constraints on the variables. Steady-state material balance equations fit in this category. The basic Lagrange-Multiplier method is described. It is followed by a description of the modified material balance data adjustment technique. An example is presented to illustrate the use of this method.

Jan 1, 1970

By Chinmay Shingote, Robert Visintainer, Renjie Ke, Jaikrishnan R. Kadambi, John Furlan

Hydrocyclone separators are widely used in various industrial applications in the oil and mining industries to sort, classify, and separate solid particles or liquid droplets within liquid suspensions, which are considered to be multiphase systems. Numerous valuable studies have been conducted in recent years to investigate the flow fields inside hydrocyclones. However, much of the information regarding the performance of cyclones in the literature has limitations and much of it cannot be considered as completely applicable to most real-world applications; many of the studies investigated the flow fields within extremely simplified hydraulic designs that are not representative of the complex geometries or large sizes which are typical in industry. Therefore, in this study, the two-phase flow system inside the actual hydraulic geometry of a milling circuit hydrocyclone is explored with the aid of both computational and experimental techniques (particle image velocimetry (PIV)). More specifically, the flow field with an air core has been investigated. In addition, the air-liquid two phases flow in a hydrocyclone might cause some challenges on both the computational and experimental sides. Two turbulence models are utilized in the numerical calculations: the Reynolds stress model and large eddy simulation. The computational studies are mainly focused on the local flow behavior and the prediction of the dimensions and shape of the air core. Different section planes of hydrocyclone are selected as planes of interest and divided into several fields of view (FOV) for PIV measurements. Two-dimensional experimental velocity vector maps are obtained in each of the fields of view. The computational results are validated globally using pressure and flow rate readings at the boundaries and locally by comparison to the PIV velocity vector maps and profiles.

By J. C. Weimer

The goal of Bethlehem's mining research program is to improve both the safety and productivity of our mines through the use of new equipment, new technology and new mining methods. Although we can all agree on the value of such goals, achieving them can be a costly, time-consuming and sometimes frustrating experience. However, the potential benefits of lower costs per ton and better safety in an increasingly more stringent and confusing regulatory environment make the expended effort worthwhile. At Bethlehem we feel that the mining companies are in the best position to determine the needs of the industry, and coal companies have the incentive as well as mine sites at their disposal for testing. Therefore, the mining industry should be leading the research effort

Jan 1, 1979

By R. L. Bleifuss

The object of this study was to evaluate the oxidized taconites of the western Mesabi iron range and to establish a correlation between the various basic taconite types and their concentratability. This study was made at the Mines Experiment Station of the University of Minnesota under the sponsorship of the Great Northern Railway Company. The initial work included a study of the original mineralogical and stratigraphic facies of the fresh taconite and traced the oxidation and leaching patterns developed during the conversion of this material to oxidized taconite. Subsequent studies have extended this work to include the semi- taconites and also the wash and heavy media ore types widely developed in the area. Each basic, original mineralogical facies or taconite type produces during alteration an equivalent secondary oxidized facies which has a unique mineralogical composition and texture. These control the concentratability of the oxidized taconites. Actually the influence of the original mineralogical composition of the iron formation extends even further and determines whether the most likely product of oxidation and leaching will be a wash ore or a heavy media ore and even to the direct shipping ores where the ratio of hematite to goethite is largely determined by the original taconite type.

Jan 1, 1964

By K. L. Wiley

In-situ leaching, initiated in 1986 at San manual, was economically developed in 1989. The primary reason for this lag time between startup and viable production was the time required for technical development. The technical development pursued comprised detailed design, development, and implementation of in-situ well construction methods, formulation of suitable well pattern arrays, and the development of extensive hydrogeologic and geochemical knowledge of the mineral deposit. Since 1989, the in-situ leaching program has become a viable and cost effective method to extract copper from the supergene mineralized zone of the San Manuel deposit. The in-situ leaching methods that are currently utilized have been progressively expanded and continually developed and will became the cornerstone of copper production from the San Manuel oxide mineral deposit. This paper presents an overview of the supergene hydrogeology, current design techniques, drilling methods and well completion, pump determination and setting, solution management, and future plans for the increased extraction of copper by in-situ leaching methods at the San Manuel mine.

Jan 1, 1993

THE FUTUREGEN CLEAN Coal project will be the recipient of $1 billion worth of federal stimulus money by way of the U.S. Department of Energy (DOE), which announced the commitment to the project. The money is expected to kick off years of further work that could finally see the project completed. One of the companies involved, Ameren Corp., said the $1.2 billion project ? which will include some private funding ? still has a number of hurdles to clear.

Jan 1, 2010

By Alex G. Sciulli

According to recent estimates, nearly 30 percent of the material from underground coal mining in the United States is rejected on the surface as waste. This accumulation of almost three billion tons of coarse and fine coal refuse is primarily from coal cleaning operations. The marketable coal is intermixed with sandstone, clays, shales, and carbonaceous rocks, which must be removed and disposed of in an acceptable manner. The disposal of mineral wastes is a major environmental concern. The most common types of environmental problems associated with coal refuse disposal are acid formation, erosion, and sediment control. Other areas of concern include air and water quality, combustion control, mine sealing, and reclamation. This paper focuses on these topics and attempts to outline special environmental features which can be incorporated into the design and construction of a coal refuse facility. Often these measures can minimize and possibly eliminate the potential environ- mental hazards. It is imperative, however, that these measures be adopted prior to and during construction, because of the relative ease and cost savings compared to post-construction implementation.

Jan 1, 1983

By William J. Bryson

Just picture, if you will, the hot, lonely and desolate Ochre Mountains west of Salt Lake City. There works a grizzled old miner, his boots worn down, his clothes hang on a body stooped by years of hard labor. His skin is wrinkled and leather toughened by many years in the hot desert sun. His ever faithful burro stands patiently in the shade of a large rock as the tired old miner examines ore samples just acquired that very morning. Suddenly the old man's eyes widen, his breathing becomes rapid. 'Leaping to his feet, with a gleam in his eye, he cries, "Eureka, I'm rich, I've found the mother lode. This is where I will start my digging. " Without warning, the silent wilderness is alive with wild, shouting, charging figures! Frightened the old miner glances about him wide-eyed and pan- icky. His heart sinks, dismayed he now knows all is lost, this is the end. For there leaping from behind rocks and brush papers in hand, are the men from the Department of Interior, Bureau of Land Management, State Mine Inspectors, OSHA, MESA, EPA, OEO, and the never ending list of regulatory bodies related to todays mining industry.

Jan 1, 1975

By John D. Kalasky

Ventilation is necessary in coal mines to supply fresh air to the working faces for the health, safety, and comfort of the miners, and for the circulation of air to the extent that it will dilute, carry off, and render harmless the noxious or dangerous gases generated. Adequate ventilation depends upon good face control, as well as upon a well designed and properly controlled overall ventilation system. Generally, this includes fans, airways, overcasts, air locks, regulators, checks, and canvas or plastic stoppings near the working places to prevent short circuiting of air, and effective bleeders to maintain a continuous flow away from the working places along the pillar lines at all times and to prevent diffusion of methane back to the pillar line in case of temporary interruptions in ventilation. In the development of a new mine, or the virgin area of an old mine, the main headings should properly be considered a construction project, designed with, only the number of permanently supported (roof) headings required to conduct the necessary air volume to and from the major panels in which mining is conducted by room and pillar or longwall methods. Although subject to hazards from methane quite frequently and requiring constant and careful attention at all times, development of headings has some built in safeguards which make it a less difficult problem in control of methane than exists in pillaring.

Jan 1, 1973