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By Cherie M. Tilley

Dynatec Mining Contractors (Dynatec) entered into a contract with Barrick Goldstrike Mines (Barrick) to develop the deep gold ore reserves at the Meikle Mine north of Carlin, Nevada. The Ventilation and Production Shafts were started in early 1994 and were completed in December, 1995. The mine development and mine construction programs were completed in November, 1996. This paper describes the Meikle Mine development program.

Jan 1, 1997

By Kenneth S. Johnson

Western Oklahoma, with an estimated 48 billion tons of minable gypsum, has one of the largest reserves of high-purity stone in the United States (Figure 1). Gypsum beds of the Permian Blaine Forma¬tion are 10 to 30 feet thick in the southwest and northwest regions, and the Permian Cloud Chief Gypsum is 20 to 90 feet thick in the west-central region (Ham, 1962; Ham and Curtis, 1958; Scott and Ham, 1957). Republic Gypsum Company, in the southwest part of the State, is Oklahoma's second-largest gypsum producer. Since opening its plant in 1964, the company has steadily increased production and now accounts for about 15 percent of the State's annual output. The plant and quarry are 15 miles west of Altus at Duke, a small commu¬nity on the Hollis and Eastern Railroad in northwestern Jackson County.

Jan 1, 1970

By Robert N. Evans, Delon Hampton

During construction of the Washington Metropolitan Area Transit System, the hand-mining of a mixed-face condition was anticipated on a portion of tunnel located in the downtown area of Washington, D.C. The Section, consisting of two circular tubes, extends from Station 12+80, heading in a westerly direction, traverses along a curve under Lafayette Square, and ends in a northwesterly direction at Station 37+62 (see Fig. 1a). It was near the northernmost portion of the section that the mixed-face condition was encountered. Decomposed rock was first encountered in the invert at Station 31+00. From this point the rock gradually increased in height until it intersected the springline at Station 37+62, the project limit. Summarized within this paper are measurements of the soil load on a horseshoe-shaped portion of tunnel located in the mixed face condition. These measured loads are compared to the soil load on tunnels as determined by current design methods. The paper also discusses rib and surface movements associated with the post loading process. Comments will be made on how the presence of a mixed face condition might help or hender the tunnel design and construction procedures.

Jan 1, 1974

By James J. Snodgrass, David E. Siskind

The Bureau of Mines investigated the effects of vibrations from underground blasting in four rock types to define blast parameters that affect vibration amplitudes and to establish means of predicting expected vibration levels. Previous studies of surface blasting indicated that charge weight per delay period had a major influence on vibration amplitudes. Dividing the distance from the blast by the square root of the charge weight scaled the effect of various charge weights, however, and allowed vibration data for a particular site to be represented by a propagation equation of the form v = K(D/W ½ )-n (1) where v = particle velocity, D = distance from the blast, W = maximum charge weight per delay period, and K and n = empirically determined site constants. For square-root scaling, particle velocity and acceleration data from the underground sites appear to follow a similar propagation law. The subsurface data are in good agreement with those of the surface studies and provide a basis for engineering estimates of vibration amplitudes in many different rock types.

Jan 1, 1974

By E. D. Attanasi, J. H. DeYoung

Several factors contributed to continued declines in mineral-exploration activity in the US in 1985. Low metal prices and, what appears to be worldwide chronic excess capacity in copper, molybdenum, lead, and uranium, have resulted in mineral-exploration expenditures remaining anemic. Economic recovery could result in a healthier mining industry and more cash flow to fund exploration. This is because general economic activity and US mining industry activity have historically been closely linked. However, as the worldwide economic recovery has expanded, the mining sector has continued its downward slide. New cuts in industry exploration budgets in 1985 shocked those who thought the exploration situation could not become worse. Some personnel and equipment had been redirected from base metals exploration to precious metals in the past few years. Last year, continued reductions in exploration sent many professionals out of the mining industry. Recent staff reductions or consolidations of operations were made by Noranda, Chevron, Molycorp, and other exploration companies. The latest data from the Society of Economic Geologists (SEG) summary of exploration statistics show that professional staff at year end in major US exploration companies (domestic and foreign operations) fell from 2355 in 1981 to 1868 in 1983 and 1277 in 1984. By the end of 1985, two economic trends were established that could improve the future profitability of mining and hence exploration. First, the price of crude oil began a decline. If sharply reduced energy prices increase worldwide economic expansion, the substantial excess capacity in some of the base metals industries could disappear, and prices could improve. Furthermore, if energy price declines reduce mining and processing costs significantly, metals may recapture some lost markets. The decline in oil revenues has already encouraged some oil-producing countries, such as Venezuela, to look toward development of mineral resources to earn foreign exchange for debt repayment. Second, the decline of the dollar by 21% during 1985 could also help US producers meet foreign competition. During 1985, industry restructuring continued as many oil companies sold off mining subsidiaries and minerals properties. Gold, silver in new discoveries Precious metals continued to dominate the announcement of new discoveries and exploration projects in 1985. A review of domestic exploration and development activities reported in several industry journals shows that 60% to 80% of these projects were directed primarily at precious metals, particularly gold. Base metals exploration activities frequently involved polymetallic deposits with gold or silver values. Because much of this exploration was done on identified targets (on-property exploration), the decrease in wildcat or grassroots (off-property) exploration may be more substantial than indicated by reductions in total exploration activity. Significant gold discoveries in 1985 included several in Nevada, among them the Genesis property of Newmont (near the Carlin mine), Goldfields' discovery of the Chimney deposit in Humboldt Co., and Freeport's discovery of two mineralized sites near Jerritt Canyon. Gold exploration continued to be focused in the western US and Alaska, but gold production starts at the Haile mine in South Carolina, and the Ropes mine in Michigan as well as Amselco's feasibility studies on deposits near Ridgeway, SC, are evidence that gold exploration is not limited to the West. The dominance of gold projects in exploration is not limited to the US, as demonstrated by gold dis¬coveries and exploration projects in Australia, Brazil, Canada, the Caribbean region, China, Guinea, Ivory Coast, South Africa, the South Pacific islands, and Thailand. From the standpoint of US metal miners, it is perplexing that worldwide exploration and development is also taking place in copper, zinc, tungsten, and other metals with depressed prices. During 1985, the US Geological Survey's efforts to map the sea floor of the Exclusive Economic Zone shifted from the Pacific Coast to the deep water areas of the Gulf of Mexico and to areas off the coast of Puerto Rico and the Virgin Islands. An atlas containing sea-floor maps of the west coast area was published as US Geological Survey Miscellaneous Investigations Series Map 1-1792. Results of the 1985 surveys are expected to be published by January 1987. Exploration trends - Statistical evidence Data from the SEG showed continued decline in the US mining industry's exploration expenditures through 1984. The share of US companies' domestic exploration expenditures directed toward base and precious metals has increased from 51% to 84% from 1980 to 1983 and to 86% in 1984. US mining companies spent about $0.67 of each exploration dollar in 1984 in the US. However, this represents an increase from earlier years. The 1983 data also show that firms spending more than $5 million on exploration accounted for 77% of exploration expenditures. Since 1981, the Bureau of Land Management (BLM) has been assembling data on claims and an-

Jan 5, 1986

By L. Hales

Neural networks are a generalized, multivariable non-linear modeling technique that can be used to model mineral processing operations. Neural networks will be described as will their use in modeling column flotation. Optimization of column flotation will be explored and discussed by using the neural network column models.

Jan 1, 1996

By A. E. Ketler

Optical smoke monitoring fills an important gap in ventilation and fire safety: namely monitoring of smoky, low temperature fires where little CO and heat are generated. Smoke monitoring also avoids the nuisance alarms due to diesel exhaust, battery chargers, blasting and welding. The smoke optical density (OD) fire alarm standard specified by MSHA presents an opportunity for improved safety. Experience of actual mine usage of the SmokeBoss*100 is reviewed, with particular regard to effectivity, maintenance and cost.

Jan 1, 1995

By Betty L. Gibbs

A clear and accurate knowledge of the status of ventilation in an underground mine is essential to continuing safe operation. In a small mine with a few working faces, the problem is simple and can easily be solved by choosing the appropriate fan. In larger, more complex mines the problem of supplying the working faces with fresh air is a problem beyond the scope of 'finger in the wind' analysis. In today's climate of stiffer government regulation and mining company concern for the safety of workers, computer programs which analyze ventilation networks are helping mining companies meet the standards. The development of computer programs for ventilation network analysis is summarized. Early programs were developed at universities or government agencies and required large expensive computers. As computers have become smaller and less expensive, the development or revision of programs for micro computers has become more available. Prices have lowered to the point of affordability even for medium and small companies. A list of ventilation network analysis programs is provided along with a summary of capabilities, costs, and hardware requirements for each program.

Jan 1, 1987

By Robert B. Gordon

The Reverse Curve Tunnel Project was located in Glenwood Canyon, Colorado approximately twelve (12) miles east of Glenwood Springs. The Project was one of many being constructed over a period of time by the State of Colorado, Department of Highways to improve Interstate 70 to four lanes as it travels thru the environmentally sensitive Glenwood Canyon. The Project consisted of excavating and concreting a tunnel approximately five hundred fifty (550) feet long, forty two (42) feet wide, and thirty two (32) feet high. The designer was Parsons, Brinkerhoff, Quade and Douglas, with geotechnical consultation provided by Woodward Clyde. CONSTRUCTION CHALLENGES There were several significant construction challenges presented primarily by the physical location of the Project. In this study each problem will be discussed, as well as how it was overcome by construction methods and/or design requirements. Portal Excavation - One of the most difficult areas of work on the Project consisted of excavation and stabilizing the East and West Portal rock prior to tunnel excavation. The Reverse Curve Tunnel passes through a sheer walled cliff face which is approximately two hundred fifty (250) feet high. Geologically the cliff consists of primarily sedimentary deposits with open, weathered joints and vertical faulting. Before the tunnel excavation could begin, a narrow sliver cut had to be excavated and rock

Jan 1, 1989

By Drupad B. Desai, Alexander Rosenbaum

In recent years, there has been an increasing use of two-pass tunnel lining system consisting of segmental unbolted expandable precast concrete initial lining and cast-in¬place concrete final lining in the United States. Used so far in soft ground tunneling performed under free air, it often includes a waterproofing or gasproofing membrane placed between the initial and final linings. This paper describes the utilization of this two-pass system for an extension of the Baltimore Metro, constructed in part under compressed air. It offers a description of the extension project, known as Section C; addresses the tunnel lining selection process and the design of the lining elements; examines the effect of the adopted lining system and tunneling technique on the design of the project's major structural components; and describes design modification instructions in order to accommodate constantly changing field conditions.

Jan 1, 1993

By Jim W. Rosteck, Anthony Del Vescovo

In December of 1992, the City of New York, Department of Environmental Protection, solicited bids for Contract 543B. The low bidder was a joint venture of Schiavone Construction Co., Inc. and the J. F. Shea Co., Inc. When completed, the project provides a 4.88 meter diameter water tunnel 8,840 meters long. This paper presents a case history of the equipment and construction methods utilized for this, the first portion of the New York City Water Tunnel constructed by use of a tunnel boring machine.

Jan 1, 1997

By Robert Cooke

This paper shows how technology developed to analyse stabilised slurries can be applied to paste flows. The rheological characterisation of paste mixtures using the generalised yield pseudoplastic rheological model is described. It is noted that the slump test does not provide a complete rheological characterisation of a paste. Methods for calculating pipeline pressure gradients for laminar and turbulent flow are presented. The minimum pressure gradient is an important consideration to ensure that solids do not settle on the pipe invert. Important points to be considered for a pipe loop test programme are noted. The usefulness of the pseudo shear diagram for scaling pipe loop test measurements is demonstrated. Issues to be considered for the design of paste reticulation systems are discussed.

Jan 1, 2001

By C. J. Webb, C. J. Paterson, A. Davis

This work focused on identifying, examining and ranking the physical and environmental hazards at inactive and abandoned mine sites in the Black Hills of South Dakota. Earlier inventory projects in the Black Hills concentrated on federal lands, while more recent efforts have examined abandoned mines on state and private lands. The more recent efforts are a result of passage of legislation by the State of South Dakota requiring a comprehensive inventory. The inventory information provides criteria for identifying those sites that require further investigation or characterization of the physical safety or environmental hazards. For most AML sites in the Black Hills, location information is all that is typically needed, because the majority of sites pose little environmental or physical hazard.

Jan 1, 1999

By A. K. Mukhopadhyay

[The mechanical status of a mine ventilation fan can be monitored effectively through vibration analysis. An expert system can be an effective tool in fault diagnosis for a variety of equipment. Computers have made it possible to implement an expert system to analyze the data for correct and appropriate diagnosis. In addition, vibration analysis can provide important information oil the condition of the machine. This paper discusses an approach for an expert system to determine on vibration analysis, practical problems that can occur with a fan. The frequency of the vibration is the only characteristics considered in the analysis, although other variables are discussed in the paper. Finally, a simple computer program, written in Turbo Prolog, is presented. A friendly query system, menu operation and a disk-resident separate knowledge base are a few of the salient features of this system.]

Jan 1, 1997

By H. Walqui, J. Drelich, J. Pletka, E. Luhta, E. Raber, J. Wieland, P. Boyd, N. Tervo, D. Herron, S. Boston

Mini-projects studying the flotation chemistry of paper de-inking were incorporated to an educational program at Michigan Technological University with support from the paper recycling industry. Interfacial activity of frothing agents, surfactants and polymers in de-inking flotation systems has been studied through flotation, atomic force microscopy, zeta potential, contact angle, surface tension, and froth stability measurements. These fundamental studies were developed to understand microscopic and molecular effects occurring in flotation of ink particles that may lead to improved designs in de-¬inking flotation processes. Fundamental studies indicate that ethoxylated alcohols are efficient frothing agents in flotation and can be used to clean the recovered paper from hydrophobic ink particles. Next, it was further supported in this research that the fatty acids activated by calcium ions act as collectors in flotation of ink particles. Finally, improvements in de-inking flotation are reported in laboratory tests involving aqueous solutions of polymeric flocculants.

Jan 1, 2001

By Shuyu Qin, Shujiang Sun, Jingfu Zhao

The three key parameters of mine fires are local airflow velocity, temperature and oxygen concentration. According to the theories of seepage in porous media, heat transfer and heat dispersion, mathematical models were constructed based on the three parameters. The models can be used for early prediction of mine fires and for estimation of the level of spontaneous combustion. Proper use of the models can assist in preventing and controlling mine fires. KEY WORDS: airflow velocity, temperature, oxygen concentration, numerical modelling, mine fire prediction.

Jan 1, 1993

By Raymond J. P. Brouzes

INTRODUCTION [A Decade After the 1972 Stockholm Conference] The UN-sponsored Stockholm Environmental Conference held just over 10 years ago was the first successful attempt to achieve global recognition of environmental issues. Indicative of the lack of concrete involvement in environmental protection to that time was the fact that only 15 nations had a department or ministry responsible for environmental affairs compared to today's 143. Many governments were uncertain of what were the most serious or pressing problems in their country. There was obviously a need to both identify those issues and to determine how to manage them once identified. At the same time, the public at large was becoming more critically aware that environmental protection had been neglected by government and often ignored by industry. It soon became evident that large amounts of money would have to be spent to redress some of the more evident problems. However, many developing nations were reluctant to slow down the much-needed industrial growth by imposing costly environmental controls on industry. In fact, some waived environmental control altogether as an incentive to attract industry. In some sectors, it was often stated that industrial development and environmental protection were mutually exclusive activities. The need of an awareness, commitment and dedication by all sectors of society to protect their environment was just beginning to develop, replacing the rather simplistic view that all environmental problems were caused by greedy industry.

Jan 1, 1984

By J. C. Mullen

Today, the coal mining industry is more knowledgeable on the potential negative economic consequences associated with improper management of hazardous substances and various types of solid waste. The practices evaluated during environ-mental audits are discussed and example situations are shared from previous audits of coal mines and analogous situations. The importance of assessing and understanding purchasing, warehousing, safety, maintenance, electrical, operations, and environmental management practices and procedures is highlighted as a key to a successful and practical program. A waste minimization approach is presented including strategies for screening product purchases, product substitutions, and testing and record keeping.

Jan 1, 1992

By J. R. Diehl, R. W. Lai, R. W. Hammack, S. U. M. Khan

Cyclic voltammetry (CV), flotation response, evolved-gas analysis (EGA), and X-ray photoelectron spectroscopy (XPS) were employed to evaluate the major differences in the surface property and surface reactivity of a selected coal pyrite and a mineral pyrite. Surface properties of pyrite were evaluated in terms of flotation response in the presence of both an anionic fluorosurfactant and sodium hydrosulfide. The charge transfer adsorption and oxidation potential of sodium hydrosulfide were evaluated using cyclic voltammetry. Drastic differences in the flotation response have been observed between the coal pyrite and the mineral pyrite. Significant differences in the cyclic voltammograms at pyrite surfaces of these two sources were also observed. Measurements by XPS and EGA were used to determine the oxidation products and the rate of oxidation of the coal-pyrite and the mineral-pyrite surfaces.

Jan 1, 1991

By Karl Gunnar Holter, Frank Clement

"INTRODUCTION Typically waterproofing of conventionally excavated tunnels has been done by installing pre-fabricated sheet membranes between the primary temporary support lining and the secondary permanent inner lining. The membrane acts as a separation or sliding layer between the linings, which is often desirable. The geotextile installed behind the sheet membrane provides the required drainage and protection of the system. The design of the tunnel lining is strongly influenced and limited by the use of waterproofing sheet membranes. Since primary and secondary linings are separated from each other, forming a double-shell lining system. In that case the secondary lining must be designed for all permanent loads, although the sprayed concrete primary lining continues resists ground and water loads for a long time after construction. Significant progress has been made in sprayed concrete technology over the last two decades, with advanced admixtures, as well as the improved application technology using spraying robots. The development of new admixtures like superplasticizers based on poly-carboxylates, alkali free accelerators and silica fume, enables designers to use permanent sprayed concrete linings (SCL) increasingly for long-term service life. When designed and applied correctly, sprayed concrete can be considered as permanent. The use of spray applied membranes has seen increased use over the last decade in some countries, and demonstrated functionality and cost-effectiveness in several situations. This paper describes the use of the sprayed waterproofing membrane MasterSeal 345, an EVA polymer based product, and the practical experiences from several projects. SPRAY APPLIED WATERPROOFING MEMBRANES The sprayed waterproofing membrane is polymer based and has been especially developed for underground structures. The membrane is applied between primary and secondary concrete linings and develops high bond strength on both sides to the concrete (doubled-bonded)."

Jan 1, 2016