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By F. W. Metzger

Coal quality control in mining and mine planning has always been important and has become even more essential in recent years due to environmental considerations. The primary consumers of the sub-bituminous coals found in the Powder River Basin of Wyoming are electric utilities that require low sulfur coals to meet government air quality regulations. Electric generating plants are designed to burn coal of a specific quality, and the supplier of that coal must be able to guarantee shipments within specified quality tolerances. Over the past several years, Exxon Coal USA and, more recently, The Carter Mining Company, a division of Exxon Coal USA have established an evaluation and development program to accurately define the geology and quality of their coal properties. This requires an adequate drill hole density so that detailed correlations of the coal seam and the lithologic sub-units, of the coal seam can be made. These units must be recognizable in the core and also on geophysical logs.

Jan 1, 1981

By K. H. Bettles

The Goldstrike Mine is in Eureka County, Nevada, approximately 23 miles northwest of the town of Carlin. The mine is at the north end of the Tuscarora Spur of the Tuscarora mountains at elevations of 5,300 feet to 5,950 feet. It is part of the Bluestar/Goldstrike subdistrict of the Carlin Trend of sediment hosted, disseminated gold deposits. The Carlin trend comprises over 15 major gold deposits with production, reserves and geological resources of approximately 50 million ounces of gold (Fig. 1). In the Bluestar/Goldstrike subdistrict, there are four major deposits; Post, Betze, Bluestar, and Genesis, plus numerous smaller deposits (Fig. 2). Betze is located on property controlled by Barrick Goldstrike Mines; Bluestar and Genesis on Newmont Gold property; and Post on both Barrick and Newmont property.

Jan 1, 1989

By Robert P. Larkin

The necessity for mineral extraction and its impact on man and the natural environment is a subject of increasing concern to Americans. Rising living standards and new demands for energy require increased mineral extraction, whereas the "new environmentalism" and concern over social well-being warn of the dangers to both the environment and the social system. This dilemma can only be solved by a complete understanding and analysis of all the factors relevant to human welfare which include environmental considerations, economic implications, and the social and psychological dimensions. A decision-making framework is therefore necessary which will encompass all relevant views of the problem.

Jan 1, 1975

Energold Drilling Corp. is a leading specialty drilling company servicing the mineral and energy sectors in the Americas, Africa and Asia. Energold specializes in mineral exploration in remote locations with limited infrastructure. Such locations require the smallest footprint possible going in, leaving as little or no evidence on their way out. Energold?s rigs can be transported by helicopter or manually on footpaths as narrow as 1 m (3.3 ft). They set up quickly and then are struck and packed out, with any sign of their presence quickly disappearing behind them. Energold has teamed up with Atlas Copco and its team of engineers in North Bay, Ontario to design small rigs capable of drilling to a variety of depths, as required for each project.

Jan 1, 2013

By H. H. Murray

New and improved benefication techniques are available to allow the production of clay minerals of exceptionally high purity. This is particularly true for kaolins and smectites. Wet processing techniques including particle size separation, high intensity magnetic separation, chemical leaching, flotation, and selective flocculation are described and results and applications are discussed. The blending of clay minerals with other minerals provide opportunites to make special ceramic materials such as cordierite and other minerals which have very special ceramic properties including low heat expansion, high fired strength, low absorption, and other desired qualities.

Jan 1, 1989

By F. L. Pierson

Since the discovery of 'potash in the Carlsbad area in 1926 and the start of mining operations in 1931, "first mining," operations have been carried on. This is a room and pillar system in which approximately 62% of the total ore is removed. Or the basis of ore reserves and rates of extraction, the life of the mine in the early; days was estimated to be well over 50 years, however, even with an increase by additional ore reserves, it became increasingly apparent that the life of the mine was being shortened considerably by increased production. Further cause for the shortening of mine life was due to the exceptionally weak back over the northeast quadrant of the main orebody which had .caved in on first mining up to a height of 8 feet. Thus, in 1953 the decision was' made to begin pillar pulling, also called, second mining or final mining, and in December of 1953 this program was started after much discussion.

Jan 1, 1965

By J. E. Friant

The Mini-Disc TM cutter drill bit is a radical design departure from the traditional tri-cone rock drill bit. Miniature disc type cutting tools as small as 3.25 inches (82.5 mm) diameter are fitted to a bit body to cut individual concentric kerfs. The action is the same as that commonly used on large tunnel boring machines but miniaturized. The high performance rate and efficiency of a disc cutter are the result of producing a large proportion rock chips rather than sand or powder. The Mini-Disc TM drill bit, referred to as the "Disc Bit" has other unique features as well. It can be re-greased between runs. It can be rebuilt in the field in about 15 minutes, cutters can be replaced and the Disc-Bit appears to require less down hole hydraulic power than conventional bits. Thoroughly tested in the laboratory, the bit has recently been undergoing field trials in well drilling, blast hole drilling and shaft drilling. As any engineer knows, the laboratory cannot shake out all the problems but it eliminates the more glaring weaknesses. Performance results have been exhilarating, and a few mechanical problems were discovered and largely overcome. This paper is a progress report.

Jan 1, 1999

By Joseph E. Worthington

Increases in the price of gold starting about five years ago, and rapid fluctuations since then, have caused a substantial popular interest in the noble metal. Gold prospecting had been at low ebb since the end of World War II in most of the United states except for a flurry of activity in Nevada occasioned by the Carlin and Cortez discoveries. The last five years, however, have seen a great awakening of interest in gold exploration as well as an opportunity for education for many explorationists in the geology and other vagueries of gold deposits. The present writers have participated over the last few years in a search for gold deposits throughout the United States. This search was greatly influenced by the geologic studies of Dr. Wm. Spence at the Haile Gold Mine in South Carolina as reported in a companion paper. Spence's studies resulted in definition of a geologic model that has proven useful in a number of other geologic environments in the united states. These programs were all carried out under the auspices of Cyprus Mines Corporation and permission by Cyprus to present these results is gratefully acknowledged. The writers, however, reserve for themselves all responsibility for the results and conclusions. The exploration program to be described began in the southeastern United States. Spence's studies provided a reasonable basis for interpreting and understanding the geology of the Haile deposit and also provided a means for predicting additional occurrences. This concept was then expanded to other gold occurrences in the Piedmont and became an effective tool for evaluating other prospects. Finally it became evident that the concept could be applied in some western gold districts. The following discussion will then include descriptions of other Piedmont examples and a few western districts that also appear to fit the pattern.

Jan 1, 1978

By J. A. Herbst

Until the past decade, the energy-size reduction relationship was the dominant form of mathematical model used in the description of tumbling mill grinding processes (1,2). Typically, in these models some single measure of product fineness (e.g. the 80% passing size, the size modules, the specific surface area) is chosen as the dependent variable and the energy input per unit mass of material being ground acts as the independent variable. In some instances these models have been useful for the correlation of experimental data, but, invariably, they have been found to be inadequate for meaningful process simulation. During the last decade considerable advances have been made in the development of phenomenological grinding models derived from population balance considerations (3-7). In these models a set of dependent variables is employed, corresponding to the set of mass fractions which constitute the product size distribution, and energy input is abandoned in favor of "time in the mill" as the independent variable. The phenomenological models have been shown to provide accurate simulations of the entire size distribution of ground products produced in batch (8-10), locked cycle(11)and steady and unsteady state, open and closed circuit continuous grinding(12,13).

Jan 1, 1973

By C. M. Walck

The Rosebud district is located in the Kamma Mountains, southeast of the townsite of Sulphur, Nevada. Since discovery in 1989, LAC Minerals, in joint venture with Equinox Resources, has delineated a resource containing approximately 570,000 ounces of gold and 5,500,000 ounces of silver. The deposit is of the volcanic-hosted epithermal quartz-sericite type. Mineralization occurs in tabular zones in and along the hanging wall of the South Ridge fault, and in cross-cutting high-angle structures. Multiple stages of discontinuous stockwork gold-and silver-bearing quartz-calcite-clay veins cut variably clay-altered, silicified, and sericitized rhyolitic Miocene volcanic rocks.

Jan 1, 1993

By Andrew Chegwidden, Tara Wilk

Shaft 18B-1 is the second shaft to be constructed as a part of contract C547A along the New York City water supply system Tunnel No. 3. More complex than Shaft 17B-1, this site has an additional 30 m (100 ft) of overburden for a total excavation depth of approximately 78 m (256 ft) through water-bearing overburden soil and 145 m (475 feet) of gneiss bedrock to connect to the underlying Water Tunnel No. 3. round freeing was specied as the method to provide temporary earth support and ground water control for the overburden material. An extensive supplemental geotechnical investigation (SGI) and frozen soil testing program was performed to develop the design of a temporary ground freezing system, consisting of over 7,315 m (24,000 ft or 4.5 miles) of drilling for the installation of 95 freeze pipes. At the start of shaft excavation, the upper sandy silts strata was found to have an unprecedented low thermal conductivity, leaving the frozen soil face approximately 0.6 to 1 m (2–3 ft) behind the cutline. The ground freezing earth support needed to be augmented with ring beams and liner plates to support this soil face and allow for the excavation to proceed and be completed safely.

Jun 23, 2024

By T. A. Gray

There are several potential large-volume uses for coal ash in mining-related applications that could be environmentally and economically beneficial to mining companies. Actual usage, however, may be constrained by regulations or by perceptions of coal ash and the potential uses. To identify currently allowed uses and to assess constraints to coal ash use in the eastern coal fields, questionnaires were sent to state coal mining agencies to determine their policies on coal ash utilization and to mining companies to solicit their viewpoints on coal ash utilization. Identifying and understanding the constraints will allow for the development of a coordinated and consistent approach to remove or reduce these constraints and possibly allow for increased utilization of coal ash by the mining industry. This paper summarizes the findings of our investigation.

Jan 1, 1995

By Harry Perry

The Bureau of Mines is glad to have this opportunity to discuss its present Coal Research Program and its significance to the industry with a group which has for many years been representative of the coal producing community. We believe we have a dynamic program that will help our vast coal resources to find their proper place in the U. S, economy. The present coal research activities of the Bureau are conducted in three organizational subdivisions: Minerals Research, Mineral Resource Development, and Health and Safety. All investigations are carried out in Bureau research facilities located in different sections of the country, Since its creation by the Organic Act of 1910 and subsequent amendments, the Bureau has worked closely with the coal industry--first by providing assistance in mine safety for anthracite and bituminous coal mining, and since that time, in providing information on conservation, safety, mining, preparation, and utilization.

Jan 1, 1966

By M. Trim, Y. Sun, D. Tepavac, A. Kumar

Configuration of Rozelle Interchange Project’s ventilation system required design and construction of some of the largest and tallest underground civil caverns attempted in Australia. The paper focuses on the technical challenges of designing these caverns within a heterogeneous, generally weak sandstone under highstress conditions while providing a construction sequence that would align with the contractor’s preferred techniques and schedule. Various construction techniques were investigated, but ultimately an observational approach relying on a construction sequence and specialized instrumentation met both the designer’s and contractor’s requirements. Relevant data obtained from excavations and the construction monitoring program are presented within.

Dec 1, 2022

By Wendell H. Wiser

A comparison is presented of coal pyrolysis at temp¬eratures ranging from 4090 to 497°C and thermal dissolution of coal in tetralin at temperatures ranging from 350° to 450,°C, both utilizing a Utah high-volatile bituminous coal. The initial coal pyrolysis reactions are second order with an enthalpy of activation of 35.6 kcal per mole. The fraction of total product yield produced under second order conditions ranges from 67% at 409°C to 96% at 497°C. The process then gradually deteriorates to a first order reaction in the later stages with enthalpy of activation of 4.1 kcal, per mole. The initial reactions of solution of coal in tetralin are second order with an enthalpy of activation of 28.8 kcal per mole. The fraction of total product produced under second order conditions ranges from 63% at 350°C' to 94% at 450°C. The dissolution process then gradually changes to first order in the later stages with enthalpy of activation of 15.6 kcal per mole. A model is presented which relates the two processes and explains, the significance of the above similarities.

Jan 1, 1967

By R. B. Hopler

Explosives R&D has historically been motivated by coal mining. Whether to solve safety problems or to improve productivity and cost, the result has been the same: better explosives products and initiation systems. This process continues at an accelerated pace today due to the tools presently available to the explosives and mining industries.

Jan 1, 1993

By P. Soros

To accommodate the immediate and long term growth of the Hunter Valley, one of Australia's major coal producing regions, a third coal terminal was required in the Port of Newcastle, N.S.W. The initial capacity required was 15 million tons per annum, made up of 40 different blends, to be expanded to 50 million tons of 100 different blends, made up from 70 grades. Coal arrives in 3,200 ton unit trains, a total of 16,000 trains in a year.

Jan 1, 1986

By Takahide Wakamatsu

In Japan all the complex sulfide ore deposits of base metals have been developed as underground mining. The underground mining cost is extremely high as compared with open pit mining case. Therefore, in milling section of base metal mines, technical advance for maximum recoveries of valuable constitutents in ore has been required all the time to utilize as much ore mined as possible. At present, in mill plants treating "Kuroko", complex sulfide ore, concentrates of copper, lead, zinc, pyrite and barite are produced, with gold and silver contents in the copper, lead, and zinc concentrates being estimated as extra profit. As in the case of Kuroko milling plants, gold and silver contents in the lead and zinc concentrates of lead-zinc ore milling plants are also varuable from an economical viewpoint. Silver content is very high in Kuroko crude ore as well as lead-zinc ore.

Jan 1, 1982

By B. R. Addison

In the Spring of 1991, Georgia Marble Company of Arizona (GMCOA), acquired the Andrada Marble Company located near Vail, Arizona, approximately 32 km southeast of Tucson. The Georgia Marble Company operation consists of an open pit quarry and a recently constructed, state of the art calcium carbonate milling and processing facility. The open pit quarry exposes white, crystalline, CaCO3, Escabrosa limestone that meets our customer criteria for Consumer and Industrial Filler applications. The Georgia Marble Company Arizona Division facility is designed and engineered to produce a wide range of milled calcium carbonate that includes finely ground and coarse screened products.

Jan 1, 1994

By M. L. Free

Acid consumption in copper heap leaching is determined by the minerals present in the ore. Gangue minerals such as biotite and chlorite consume acid together with copper-bearing minerals such as chrysocolla and malachite. Acid consumption is affected by the rate of acid application and the particle size. Some gangue minerals undergo alterations and cause precipitate formation during acid leaching. Other minerals form due to precipitation as dissolved ion concentrations from a variety of mineral sources combine to exceed saturation levels. Copper recovery is related to all of these events. This study presents information on acid consumption of various gangue minerals as well as data for copper recovery from an associated copper ore.

Jan 1, 2010