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Fine coal is substantially more costly to process than coarse coal because of technical difficulties associated with separating fine particles and removing process water from both clean coal and refuse. Therefore, companies are often forced to discard coal fines to waste impoundments. According to a recent report published by National Research Council, the U.S. coal industry is discarding 70-90 million tons of coal fines annually to 713 active impoundments, most of which are located in Central Appalachia. On October 11, 2000, a 72-acre impoundment near Inez, Kentucky, accidentally released 250 million gallons of coal slurry into nearby underground mines, creeks, rivers, and schoolyards, thereby creating serious environ-mental concerns. Fortunately, recent advances in separation technologies make it possible to recover fine coal more efficiently from existing coal preparation plants and from waste streams previously discarded to impoundments. The availability of these new technologies allows companies to increase profitability and minimize environmental risks, which are conducive for achieving sustainable mining.

Jan 1, 2003

By Justin R. Patts, Andrew B. Cecala, A. KYLE LOUK, Emily J. Haas

The National Institute for Occupational Safety and Health (NIOSH) and the former U.S. Bureau ofMines (USBM) have given a significant effort over the past four decades in researching and developing engineering controls and interventions to reduce mine workers’ dust exposures during the bagging and palletizing of industrial minerals. Workers performing manual bagging and palletizing of 50- to 100-pound bags typically have some of the highest dust exposures of all workers at mining and mineral processing operations. This paper will provide an overview of available dust control technologies for bagging operations and present the findings of a recent case study that was conducted at four different industrial sand operations to identify the current types of bagging and palletizing technologies being used and to evaluate their effectiveness in reducing workers’ exposures to respirable crystalline silica dust. An evaluation will also be performed to determine if further reductions in respirable dust levels can be achieved by incorporating additional modifications or improvements into the existing technology.

Apr 3, 2020

By Jeff Salai

The CP-3A contract is the final segment of the MWWST’s 28.3 km (17.6 mile)pressurized water supply tunnel for the metropolitan Boston area. The 1,288 m (4,226 feet) of U-shaped tunnel alignment passed through five rock zones employing four different primary support systems. The short tunnel began in Weston, Massachusetts, at Shaft 5A in soft, completely weathered argillite, passed through a fault zone, and ended in Dedham granite. An 18-foot diameter horseshoe starter tunnel was built to accommodate a 4.94 m (16-foot 2 1 / 2 inch) diameter Robbins TBM. Heavy water inflows were anticipated and subsequently encountered during probe drilling. Pre-excavation grouting was implemented at high pressures to displace high water inflows in the starter tunnel and consolidate the fault zone. This paper will provide an overview of the tunnel construction with an emphasis on ground control, grouting and survey control.

Jan 1, 2001

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

By L. A. Clark

Although vein-, syenite-, and pegmatite-type deposits are known in Saskatchewan, recent intense exploration stems from discovery of several exceptionally high grade uranium and uranium-nickel deposits locallized near the basal unconformity of the 1.3-1.4 b.y. Athabasca Sandstone Formation. Graphitic basement rocks and post-Athabasca faulting or brecciation coincident with the unconformity are important in locallizing uranium deposits which form as tabular, shoe lace-like bodies with grades averaging over two percent and containing up to 50,000 tonnes U308. Some deposits have similar nickel contents. A few published sandstone analyses average 0.8 ppm uranium while basement granitoid and meta-sedimentary rocks vary from 0.5 to 20 ppm. In the proposed genetic model, traces of uranium are leached from these rocks by oxidized formation waters sweeping through the sandstone and along faults. Solutions are reduced and uranium is precipitated as basement graphitic meta-pelites are encountered along brecciated fault zones.

Jan 1, 1979

By R. H. King

This paper describes the results of an underground coal mine trial installation of a shielded trailing cable. The cable was a three conductor, round, type SHC-GC, and was installed on a shuttle car in a conventional room and pillar mining section. The purpose of presenting the information is to prepare mine operators for proposed legislation that will require shielding on low-voltage trailing cables. Specifically, machine modifications are required to cable reels, packing glands, and couplers. Cable splicing is not as complex as expected but additional materials are needed in the kit and splice training is necessary. Even though shielding will cause some problems for the mine operator, it can reduce the hazard of electrical shock to mine workers. This paper will present information that mine operators can use to solve most of the problems that will be encountered if they are required to install shielded cables. The in-mine evaluation was funded by the U.S. Bureau of Mines.

Jan 1, 1980

By W. R. Reed, G. W. Luxbacher

Mine worker exposure to respirable coal dust and silica dust can result in coal workers’ pneumoconiosis and silicosis which are occupational respiratory diseases that have no cure and are ultimately fatal. In 2021 the Mine Safety and Health Administration reported just over 11,000 operating metal/nonmetal mines with the potential for silica dust exposure for just under 200,000 miners. The National Institute for Occupational Safety and Health (NIOSH) conducts respirable coal and silica dust research associated with mining through its Office of Mine Safety and Health Research. NIOSH respirable coal and silica dust research began under the U.S. Bureau of Mines (USBM), which initially examined silica dust, progressing to include coal dust, with a stronger focus after 1969 with the passage of the Federal Coal Mine Health and Safety Act. A review of extramural research to develop real-time respirable silica dust monitor is presented along with a brief history of silica dust regulation.

Feb 1, 2024

By Robert L. Marovelli

The major mining health and safety problems of concern to United States Government and private industry researchers in 1981 included the difficulty experienced by longwall operators in complying with the Federal 2 .0-mg/m3 respirable dust standard, the accident rate associated with falls of ground and materials handling hazards, and the upsurge in the incidence of disasters after the steady decline in recent years. Although the many mines and manufacturing companies involved in the research projects to be described are not specifically identified, it is important to note their significant involvement. This is not by way of acknowledgement, but rather to establish that these projects, using mostly Federal funds, represent close cooperation between the U.S. Government and the mining industry. The ongoing work to be described on the development of critical longwall dust control technology is a classic example of Government-industry participation through the phases of problem identification, planning, cost-sharing, and implement at ion.

Jan 1, 1982

By R. A. Jankowski

The U.S. Bureau of Mines has conducted a study to identify the sources of respirable dust and appropriate dust controls applicable to today's high tonnage longwall faces. The primary source of respirable dust identified is the cutting action of the shearer; however, the pct contribution of dust from coal transport through the stageloader/crusher was significant. This was primarily due to the high rate of mining, requiring rapid and constant coal transport. Techniques implemented for the control of shearer-generated dust included high drum water flow rates, deep cutting, shearer-clearer-type external water spray systems, and radio-remote control. The high water flow rates, and an enclosed stageloader with scrubber, were used to control dust during coal transport. No novel or effective control technology exists to control dust during support advance. Administrative controls for dust avoidance, and manual and batch-activated electro-hydraulic control systems were used to keep support movers out of the dust generated during support advance.

Jan 1, 1990

By William I. Weisman

Natural sodium sulfate is obtained from both brines and solid deposits. The brines almost always contain other salts with sodium chloride predominating. They may be obtained from surface occurrences, such as Great Salt Lake or from shallow subterranean deposits. Althought many sodium sulfate minerals are known to exist, only three are of commercial significance. These are thenardite, the anhydrous salt; mirabilite, the decahydrate; and glauberite, the double salt of sodium and calcium sulfate. The reader is referred to Weisman (1983) for details on mineralogy and geology of sodium sulfate minerals. Sodium sulfate deposits, either in the form of brine or solid minerals, are found in many parts of the world. Natural sources, by far, provide the primary supply of commercial grades in Canada, Mexico, Spain, and probably in the U.S.S.R., Chile, Argentina, and Turkey. In the United States, production of natural material and synthetic (including by-product) are about equal in volume and have been for many years.

Jan 1, 1984

By Eugene A. Hickok

Seismic surveys utilizing the MD-1 have been performed by Geophysical Specialties Company since 1957 in many parts of the, U. S. and Canada and in several foreign countries. These surveys have proven the refraction seismic technique to be applicable to a wide variety of engineering problems. The best known applications of the instrument have been in the, construction industry, where it is used for the delineation of material and mineral deposits and for bedrock depth determinations. Fast on-the-site depth determinations give reliable subsurface' information even in boulder-strewn soils. A widely publicized use of the MD-1 is to make rippability studies in which the instrument is used to determine the seismic velocity of the materials to be excavated. By use of special tables which correlate rippability with seismic velocities, such as those prepared by the Caterpillar Tractor Company using the MD-1, the rippability of-a specific material may be determined.

Jan 1, 1962

By A. M. Marabini

Flotation of rutile with N-benzoyl-N-phenyl-hydroxylamine (N-BPHA) has been investigated. Initially, floatability tests were performed in a Hallimond tube. The results indicated that rutile was floatable in the pH range from 2 to 4 at N-BPHA concentration between 2x10-3 M and 2x10-2 M. Selectivity against hematite was recognized when operating at pH values below 2. Following the hypothesis of the formation of a surface chelate between N-BPHA and titanium ion, this compound was precipitated from a solution of Ti(SO4) to which N-BPHA was added. I.R. spectrometry oft the rutile before and after treatment with N-BPHA solution confirmed the presence on the rutile surface of the same compound. The absorption isotherm and kinetics were determined by analyzing N-BPHA in solution with an U.V. technique. A hypothesis for the mechanism of adsorption of N-BPHA on rutile is suggested.

Jan 1, 1982

By Edward J. Harvey

Joplin, one of the most famous zinc mining camps of a bygone era, is today experiencing a healthy growth in manufacturing enterprises. Manufacturing requires water, and knowledge of its availability and quality often is the main factor in location of industry. For this reason in January 1964, on the suggestion of the former State Geologist, Dr. Thomas R. Beveridge, a study of the water resources of the Joplin District was undertaken as a cooperative effort of the Missouri Geological Survey and Water Resources now under the direction of Dr. William C. Hayes and the U. S. Geological Survey. The project area is in southwestern Missouri on the Springfield Plateau and is bordered on the west and north by the Osage Plains of Kansas and Western Missouri, (fig. l). Upland altitudes rise from 900 feet above sea level in the west to 1400 feet in the east. The countryside is rolling to moderately hilly and much is excellent farmland.

Jan 1, 1965

By D. Potter

Freeport Exploration initiated regional reconnaissance exploration programs in Irian Jaya, the easternmost province of the Republic of Indonesia in 1990 (see figure 1). Irian Jaya occupies the western half of the island of New Guinea. Freeport was awarded an initial contract of work which totaled 2.6 million hectares (6.4 million acres) and was subsequently awarded additional?concessions which added 1 million hectares (2.5 million acres). The concessions require work commitments and periodic relinquishments. Due to these relinquishments Freeport?s current land position totals l. 9 million hectares (4.7 million acres).

Jan 1, 1998

By C. E. Stack

For the purposes of this presentation, "refractory clay" is intended to include any clay suitable for refractory products and thus represents a description based on industrial application. Other common examples based on use would be white-ware clay, bleaching clay, paper clay, or cement clay. Most users and producers of refractories have specific quality requirements which determine the quality or type of clay that can be utilized. Many clays can however be interchanged or substituted in use by changing manufacturing processes or upgrading less desirable clays. U.S. Bureau of Mines publications (Ampian, 1985) categorize days into six groups. These are kaolin, fire clay, ball clay, bentonite, fuller's earth, and common clay. These are practical groupings based on clay production and usage in the United States. Among these groups bentonite, fuller's earth, and common clay are primarily composed of the minerals, smectite, illite, or chlorite, and are non-refractory. Kaolin, ball clay, and fire clay are commonly used in refractories and thus qualify as refractory clays.

Jan 1, 1986

By W. C. Lacy

It is the responsibility of educators to look ahead and prepare young engineers and scientists to cope with industrial and social problems of the future. We are faced with a review of history as well as prophesy of the future. The mining industry exists in a "bubble" with little interaction or communication with the outside. This isolation must be broken down if the industry is to survive in the U.S. and Canada. The ability to communicate with the general public and public officials is essential. Many changes are occurring that will require readjustments in technology and staffing. Aging population will result in raising retirement and increasing available workforce. This may force shorter working weeks to supply additional jobs. Environmental concerns will likely direct more attention not only to these concerns during mining, but to planning for post-mining land usage. Retraining and up-dating educational programs are required to cope with these changes.

Jan 1, 1994

By H. Kinilakodi, R. L. Grayson

In 2010, the U.S. Mine Safety and Health Administration (MSHA) began holding hearings on a new coal mine respirable dust rule, which proposed a 1.0 mg/m3 standard, a separate 0.1 mg/m3 quartz standard, and the use of single-shift samples for compliance. Small mines largely comprise the “hot spots” where dust diseases of the lungs increased dramatically over the past decade. This paper presents findings on the feasibility of small mines’ compliance with the proposed new 1.0 mg/m3 standard. It gives probabilities of noncompliance by MSHA district, average mining height and selected “hot spot” counties. Because silicosis and respirable quartz dust appear to be the primary issues related to a recent doubling of the prevalence of dust diseases of the lungs, multiple regression models for prediction of the average total quartz content of compliance samples are given. These findings have significant implications for the need for better dust control methods.

Jan 1, 2012

By S. N. McIntosh

Column bioleaching was evaluated by the U.S. Bureau of Mines as a means of recovering manganese from a low-grade ore from the Three Kids deposit in Southern Nevada. Manganese was solubilized from the ore using indigenous heterotrophic microorganisms. Diluted molasses medium was provided as nutrient for the microorganisms. The medium was recirculated through the ore bed until the sugars were spent. Two methods were evaluated to recover manganese from the sugar depleted bioleaching solution: (1) adsorption with a weak cation exchange resin followed by stripping and precipitation techniques, and (2) direct precipitation of the manganese using ammonium carbonate. Both methods removed up to 95 pct of the solubilized manganese from the medium as a carbonate salt. After manganese removal, the medium was replenished with fresh molasses and recycled back through the column. More manganese was effectively leached. This process of manganese solubilization and recovery followed by replenishment and recycling of the medium was repeated until 98 pct manganese was extracted from the ore.

Jan 1, 1993

By George J. Saulnier

The U.S. Geological Survey has developed mathematical-modeling techniques to assess potential impacts on the hydrologic system resulting from mining of coal and oil shale in northwestern Colorado. Potential impacts of oil-shale mining on ground-water hydrology have been simulated using a quasi-three- dimensional finite-difference model. The model has been used to simulate hypothetical mine-dewatering operations at two proposed oil-shale mines. Dissolved-solids distribution and solute transport were simulated with a three- dimensional finite-difference model that was used to evaluate the effects of flooding in hypothetical abandoned mines. The potential impacts of coal and oil-shale mining on watersheds were investigated using a digital watershed model. This deterministic physical- process model predicts responses of the hydrologic system to modifications resulting from mining in basins having snow as the major source of runoff and recharge. Potential impacts of coal development on surface-water quality were investigated using a river-quality assessment model.

Jan 1, 1979

By A. B. Seal, C. J. Bise

Excessive noise has long been a hazard in the coal-mining industry. Studies conducted during the mid-1970s and mid-1990s consistently show that hearing loss within the mining industry persists, in spite of regulatory requirements and sampling technology advances. When the U.S. Mine Safety and Health Administration's new health standards to protect miners from hearing loss took effect in September 2000, the potential developed to reevaluate sampling approaches with regard to noise-source hazards, such as task-based methods. This paper describes results from a Pennsylvania State University research project now being conducted at an underground coal mine. Each occupation was reviewed, and a list of tasks or processes performed by each was generated. Traditional personal noise dosimetry, static sound pressure levels and equipment sound mappings have been performed. Job tasks indicating the greatest levels of daily noise exposure and contributions to noise dose have been identified and will be discussed.

Jan 1, 2003