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By Alejandro Sanz, Juan Luis Magro, David Mazeyrie

The Hampton Roads Bridge-Tunnel Expansion Project (HRBT), initiated by the Virginia Department of Transportation (VDOT), will add two new 1.5-mile TBM bored tunnels to the two existing immersed-tube tunnels between artificial islands, part of the connection between Norfolk and Hampton under the Hampton Roads Harbor in Virginia, USA. The new bored tunnels will be built by Hampton Roads Connector Partners (HRCP), a joint venture of Dragados USA, Vinci Construction, Flatiron Constructors and Dodin Campenon Bernard. This paper covers technical discussions that led HRCP to select a Variable Density TBM to address the challenges of this tunnel project, including but not limited to (i) the diameter of the bore: a 46 feet (14.04 m) diameter machine that constitutes the second-largest TBM ever used in the United States; (ii) shallow ground-cover under the water table; (iii) challenging and varying geology along the alignment, with mixed-face conditions and different types of ground modification zones; and (iv) the high TBM operating pressures required—all these and other challenges in a sensitive marine environment.

Jun 13, 2021

By T. Malterer, R. Adams

Peat has unique physical, chemical and biological properties. These include high porosity and water retention, high absorption and adsorption properties, and high buffering capacity. In addition, peat is a rich medium for microorganism activity. Peat has traditionally been used for horticultural purposes. However, in recent years, peat is increasingly being used for waste- treatment purposes. This paper reviews North American literature on the use of peat for waste-treatment applications. The literature indicated that peat has potential for use in the treatment of municipal and on-site effluents, for the removal of low concentrations of heavy metals and for the adsorption of liquid and gaseous hydrocarbon pollutants.

Jan 1, 1997

By K. G. Sutterer

The prevalent use of coal combustion byproducts in engineering applications has been with Class C and Class F fly ash as admixtures in structural concrete. But, the use of fly ash and bottom ash byproducts from modern desulfurization processes is receiving increased attention. The University of Kentucky has been conducting research into civil- and mining-engineering applications of these products. The studies have included extensive investigation of the geomechanical behavior of the materials and the effect of mineralogy on this behavior. These studies indicate important mineralogical considerations in the selection of materials for a specific application and highlight the importance of quality control before and during usage on specific projects.

Jan 1, 1997

By Mark R. Stanton

Geochemical and mineralogical analyses of 46 samples from six drill cores in the Mayday mine pile near Silverton, Colorado, demonstrate wide variability in trace metal contents with spatial location. This variability results from the original geochemical composition of mined rocks, mixing of ore and non- ore rocks during emplacement of the pile, and weathering since rocks were placed in the pile. Weathering reactions are controlled by factors such as pile thickness (depth), water availability, microbial activity, and mineral dissolution and formation kinetics. These factors result in variable redistributions of trace metals from primary (ore) to secondary (weathering products) minerals within each core.

Jan 1, 2000

By S. Chander, A. Briceno

The effect of sample storage in argon and in air on the kinetics of oxidation of pyrite from a coal source was studied using accelerated-weathering tests that were performed in laboratory columns. Prior to the weathering tests, the samples were crushed, ground and stored for various periods of time in either argon or air. The test results showed a dramatic difference in the rate of oxidation of the aged samples. The interpretation of the differences was based on the hypothesis that the aging of pyrite led to the formation of surface coatings that changed with time. "Dry" oxidation produced surface coatings that had properties different from those produced by "wet" oxidation. The significance of these results to pyrite/reagent interactions during flotation and in evaluating the acid-mine-drainage potential of pyritic waste materials is discussed.

Jan 1, 1995

By Edita Vircíková, J. B. Hiskey, Ludovít Molnár, Peter Lech, B. J. Scheiner

This paper describes the results of a study of hydrometallurgical methods of producing sodium arsenate for the glass industry from arsenic oxide wastes occurring in carbon dioxide washing. This paper addresses the following aspects: theoretical assumptions for leaching arsenic and its oxides, experimental results of As(III) oxidation to As(V) in aqueous solutions, sodium arsenate crystallization (the system As2O5-Na2O-H2O), characteristics of the crystalline product, and pilot-plant tests using sodium arsenate in the glass industry.

Jan 1, 1993

By Jr. Watts

The American Mining Congress and the U.S. Bureau of Mines have formed a collaborative research team to develop, implement, and evaluate a comprehensive control strategy to reduce diesel particulate matter concentrations without degrading other air quality parameters at an underground noncoal mine. Other participating organizations include Caterpillar, Inc., the Mine Safety and Health Administration, and the University of Minnesota. After extensive baseline information and air quality data are collected, available control strategies to reduce diesel particulate matter exposures will be implemented, individually or in combination, and evaluated. This paper discusses the objectives and protocol of the collaborative effort to evaluate diesel particulate control technology.

Jan 1, 1995

By Paul G. Schmidt

Exxon Minerals Co. was exploring for mineral deposits in Precambrian terranes of the US portion of the Lake Superior region in the late 1960s. Exploration drilling and other activities had been concentrated on massive sulfide prospects in northeastern Minnesota, but general exploration studies and competitor scouting were conducted in other areas of the region. These activities drew attention to Wisconsin in 1969 when it became apparent that Bear Creek Mining Co. had made a discovery near Ladysmith in the northwestern part of the state. Observation of their drill hole pattern suggested that a massive sulfide deposit, since named the Flambeau deposit (Schwenk, 1977), had been found. With this background, Exxon initiated an exploration program for Precambrian massive sulfide deposits in northern Wisconsin in 1970 (Figs. 1 and 2). Northern Wisconsin is extensively mantled by Pleistocene glacial drift and bedrock outcrop is sparse. Other than iron mines in the extensive iron formations along the Wisconsin-Michigan border and Jackson County, no significant mineral deposits were known in the Wisconsin portion of the Precambrian Shield until the discovery of the Flambeau deposit. Until the mid-1970s, the only specific published literature on the Wisconsin Precambrian consisted of old outcrop locations and descriptions in journals of the Wisconsin Geological and Natural History Survey (Chamberlain, 1882; [ ] Weidman, 1907; Hotchkiss, 1915) and the summary maps of Dutton and Bradley (1970).

Jan 1, 1991

By J. Hanna, J. Jung, I. J. Anazia

Electrothermal production of elemental phosphorous (P4) generates substantial amounts of highly toxic phossy water and sludges. Because of their high phosphorous contents and lack of reliable processing technology, large tonnages of these hazardous wastes have accumulated from current and past operations. To date, the sludges are stored in ponds or above ground in special containment vessels at various locations around the country. Two samples of electric furnace phosphorous sludge (obtained from the Tennessee Valley Authority (TVA) in Muscle Shoals, AL and FMC Corporation in Pocatello, ID) were investigated using physical separation techniques to recover the elemental phosphorous and to render the residual material nonhazardous. The techniques tested include sizing, froth flotation and dispersed air oxidation. Flotation and sizing produced concentrates containing 69% - 90%P4, with recovery in the range of 60% - 87%. Dispersed air oxidation of the fines and tailings products was effective in the removal of an additional 10% - 15% of the P4 in the sludge.

Jan 1, 1993

By L. M. Klimov

In recent gears in the coal industry a great deal of attention is attached to the questions of elaborating and introducing the problems of planning and management and, first of all, in the sphere of mine production. The basis for planning of mi- ne production is complexes (sets) of problems for planning the development of mining operations based on different time periods, ensuring the follow-up of changes of mine productive capacities. Complexes of problems for planning, the development of mining operations at existing underground and surface mines within the OASUugol system (Coal Industry-wide Automatic System of Management) are aimed at ma- king decisions close to optimum, i.e. general lay-out of panels, blocks and pillars; transport and ventilation networks; schedules for working out parts of mine take; coordinated mining operations with limited labour and material resources; control of mining operations and ultimately maintaining productive capacities of existing mines at the required level.

Jan 1, 1979

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Jan 1, 1985

By Cleophus Short

[Of the many occupations in and about the coal mines, those of the haulage crews are among the most hazardous. Statistics ship that the second greatest number of fatalities about the coal mines occur during haulage ion and through the use or misuse of haulage equipment. During the five year period between January 1, 1957 and January 1, 1962, the m stone mine had a. Sack haulage frequency of 4098 and mined 3, 541,939 toads per haulage fatality. Coal mire haulage is similar in respects to railroading. We gee very serious consideration to the instillation of tack and to the selection of the haulage crews. In doing this, we are attempting to have our coal mine haulage as. Safe as that of the railroads.]

Jan 1, 1963

By R. L. Grayson

Evidence has accumulated indicating that cultural change toward safer workplace behaviors is beginning to occur systematically in the coal industry. Through a range of programmatic mining company successes, enforcement and litigative actions, economic responses to competition, and integrated efforts by federal and state agencies, a broader participation of safety and training professionals is being achieved to address prioritized workplace problems at mines. Small steps in workplace-related improvements have been realized already, but the trends in industry safety statistics, coupled with focused programmatic initiatives, indicate that more definitive and systematic steps are occurring to improve safe behavior in the workplace routinely.

Jan 1, 1996

By John E. Urosek, Jack E. Tisdale

The Mine Safety and Health Administration (MSHA) has developed a Mine Ventilation Bleeder and Gob Training Course. This three day course is designed to increase the knowledge and understanding of bleeder ventilation systems. It discusses concepts, designs, plan approval, inspection and evaluation of bleeder systems. This paper will introduce some of the material contained in that course, focusing on the inspection, examination, and evaluation of bleeder systems. The regulations addressing the use of bleeder systems are found in Title 30 Code of Federal Regulations (30 CFR) Section 75.334. The examination requirements are found in 30 CFR Section 75.364. Section 75.364 de- scribes specific locations where examinations are to be made and specific information to be gathered at those locations. The required locations and information will be discussed in some detail with examples and illustrations. These weekly examinations for bleeder systems are designed to monitor the parameters of the bleeder system and to evaluate its effectiveness. Over time, conditions can develop in the bleeder system that affect the ventilation and lead to hazards such as methane accumulations. The hazards of methane accumulations need to be understood as such accumulations can contribute to mine explosions. The importance of additional information gathered by the mine examiner that can assist in evaluating the performance of the system will also be discussed.

Jan 1, 1997

By E. V. Kuzmin

The rock properties improvement means the exchange of natural properties: increase of stability, strain and compress tension, reduction of gas-liquid filtering property, increase Jung- module, other mechanical and physical parameters of rocks by injection the hardening materials, such as polymeric pitches, micro-or geocements by special technology under high pressure, to fill cracks. Flow of liquid materials between the rock units and hardening under high pressure create full redistribution of rock pressure in rock massif. There are many reasons to use this technology in underground mining, tunnelling, creation barrier technology in raioactive, chemical and other danger material site etc.

Jan 1, 1996

By Jr. Wallace

This paper describes an analysis performed to determine the cool-down time of drifts in the prospective commercial nuclear waste repository in volcanic tuff at Yucca mountain, Nevada. Two emplacement methods are currently being considered at Yucca mountain. The reference configuration stores the high-level waste in short vertical boreholes, and the alternative configuration stores the waste in long horizontal bore-holes. After emplacement operations for each emplacement drift are complete, the drift will be closed off from continuous ventilation. Given time, the radioactive decay of high-level waste will increase the rock temperature around access and emplacement drifts. Air cooling may be required to re-enter these drifts. The paper discusses the analysis procedure and computer programs used to evaluate the time to cool a drift to acceptable environmental conditions 50 years after emplacement of high-level waste. Key assumptions to the analysis are presented. The results of the study show that cooling either vertical or horizontal configuration emplacement drifts is possible in a reason-able period of time.

Jan 1, 1988

By K. C. Nathsarma

An attempt was made to extract niobium oxide from ~98.5% Nb2O5 using solvent extraction processes. Nb2O5 is used as the feed material in carbothermic reduction processes aimed at producing high-homogeneity, super-conductor-grade niobium on a laboratory scale. The Nb metal used for superconductor applications requires a residual resistivity ratio (RRR) > 300, which in turn needs a stringent purity of Nb and allows impurities (substitutional and interstitial) in ppm levels only. In this paper, solvent extraction of niobium was studied under various experimental conditions, such as effect of different extractants, concentration of methyl isobutyl ketone (MIBK) in the organic phase and concentration of various acids. The concentrate was digested with hydrofluoric acid, with ammonium fluoride (NH4F) as a stripping agent. The extraction of niobium from low hydrofluoric- (HF-) bearing solution was found to be low. Thus, various concentrations of hydrofluoric acid and sulfuric acid, as well as hydrofluoric acid and hydrochloric acid, were investigated towards obtaining a maximum amount of niobium in the filtrate and a minimum amount of niobium in the residue. A McCabe - Thiele plot for extraction of niobium from the aqueous phase, HF-bearing solution using HCl with 85% MIBK in kerosene has been constructed to determine the O:A ratio and the number of stages of the process.

Jan 1, 2011

By Waclaw Dziurzynski, Janusz Tracz, Danny Wooton, Andrzej M. Wala

The purpose of this paper is to present validation studies of the mine-fire simulator using data gathered from an actual mine fire which occurred in November 1991 at the Pattiki Mine. This study evaluates the suitability of the computer software package for modeling underground fires. The paper also discusses the importance of the on-line monitoring system for the validation process.

Jan 1, 1995

By V. I. Lakshmanan, P. D. Tackaberry

The use of activated carbon as an alternative to Merrill Crowe precipitation to recover gold from pregnant leach solutions is recognized. Recovery using activated carbon, however, suffers from the interference, due to organic fouling, clay content and increasingly from the presence of elements such as copper. Ion exchange separation technology is familiar to the mining industry (uranium) and its potential application to the gold mining industry is evaluated with considerable efforts by research workers in South Africa, Australia, and North America. The present paper reviews in detail the status of the research work that identifies potential opportunities.

Jan 1, 1990

By H. T. Miller, L. M. Scott

Radiation exposures in Uranium operations may result from external beta-gamma radiation emitted by Uranium and its progeny, internal exposure to alpha and beta radiation due to the inhalation and ingestion of Uranium ores, Radon gas, and Radon progeny in mine, mill, and laboratory atmospheres and from the contamination of environmental working surfaces and clothing by Uranium-bearing compounds and ore. This paper summarizes occupational experience with reference to the exploration, surface mining, underground mining, milling and transport of Uranium by one company in the U.S. and Canada.

Jan 1, 1981