Search Documents

By Richard E. Ray, George N. Aul, Fred Garcia, William P. Diamond

Increasing longwall panel dimensions, particularly face width in gassy coalbeds, may result in unexpected increases in methane emissions. To investigate this problem, continuous longwall face emission monitoring studies were conducted at two adjacent mines operating in the Pocahontas No. 3 Coalbed, where longwall faces were to be extended from 229 to 305 m (750 to 1,000 ft). It was predicted by regression analysis of methane emissions data from 229 m (750 ft) wide longwall faces that extending faces to 305 m (1,000 ft) would increase methane emission rates by only 7 percent (0.6 m3/min (20 cfm)), to 8.6 m3/min (304 cfm) at the VP-1 Mine. In contrast, it was predicted that extending faces at the VP-3 Mine could increase methane emissions by as much as 13 percent (1.8 m3/min (65 cfm)) to 16.1 m3/min (567 cfm). The geologic and mine design factors in¬fluencing the variation in face emissions between the two mines will be discussed.

Jan 1, 1997

By Taghi Sherizadeh, Kutay E. Karadeniz, Dogukan Guner, Samuel Nowak

Seals and build-in-place (BIP) refuge alternatives (RAs) are two main underground structures to isolate an area from the active working zones with different purposes. While seals are used to prevent methane gas that seeps from coal seams and blast pressures from a possible detonation of the contained gas, RAs are used to provide a safe haven for miners who are unable to escape their working locations after an accident like an explosion or fire. The recommended BIP RA designs can be similar to seals constructed with steel-reinforced concrete. Both seal and BIP RA are constructed in different locations of the mines for a period of time, exposed to a certain convergence due to stress redistribution which can change their responses during an explosion. In this study, a steel-reinforced concrete wall to be used in such applications is simulated to examine the structural performance during an explosion for a coal mine model with different strata conditions using dynamic analysis by a 3D distinct element method (DEM) code. The main purpose of this study is to reveal any possible effects or trends on the wall deformation with changes in strata conditions by implementing different combinations of roof, seam, and floor material properties. The model is calibrated by the experiment conducted on a steel-reinforced concrete wall by the NIOSH researchers in the Lake Lynn Experimental Mine. The results show that strong adjacent rock and coal units are the least favorable condition for the survival of the wall subjected to a simulated explosion pressure. The results indicate that changes in the roof and seam conditions can have dramatic effects on the deformation characteristics of the wall when compared to the floor conditions. The results of this study might be enlightening for future BIP RA and seal applications.

Feb 8, 2023

By Bob Snashall

Mines, miners and mining figured in the revolutionary birth of the USA. This occurred with a little help from General Washington's friends, the French. When the colonial minutemen confronted King George's "bloody lobsterbacks" at Concord, MA, in April 1775, the resulting "shot heard around the world" resounded in Versailles. France was sympathetic to the patriot's struggle. Before the Lafayettes shipped out, came French muskets and powder... but not many musket balls. The Continental Congress issued orders to get the colonial lead out for shot and shell. Colonial mining enterprises had been chiefly local affairs, cheaply supplying product to the surrounding communities. Since wood was accessible for fuel, coal had not been exploited.

Jan 1, 1990

By J. J. Schwoebel

Resource Enterprises Inc. (REI) is exploiting the coalbed gas resource by working in unison with active underground mining operations. At REZ7s pilot project at the Soldier Canyon mine, Carbon County, UT, RE1 has drilled nearly 15.25 km (50,000 ft) of horizontal in-seam and slant boreholes during the initial two years of drilling activity. Produced gas has been sold to a natural gas transmission company on a continuous basis since mid 1983.

Jan 1, 1988

By Howard G. Coopersmith

A resource of low grade good quality diamonds has been discovered through the Diamond Company NL-Moonstone Diamond Corp. Joint Venture. A limited bulk sample diamond test of two large kimberlite pipes on the Kelsey Lake Property, Colorado, has been completed. These kimberlite pipes have petrological and mineralogical indications of the presence of diamond. Small diamonds were recovered from surface samples. Drilling and trenching revealed both pipes were complexes of diatreme facies kimberlite. One pipe contains crater facies kimberlite as well. This is the first reported occurrence of crater facies kimberlite in the Province. Approximately 1000 tonnes of kimberlite rock was excavated and processed through a scrubber -HMS -Sortex -Grease Plant. Significant diamonds were recovered. The diamonds were generally of good color and clarity, with many being in the gem and near gem categories. Grades are considered low however. Additionally, a small potential resource of alluvial diamonds is present.

Jan 1, 1991

By William R. Henkle

High-calcium limestone has been intermittently produced from the Monarch quarry since the late 1800s. Initial production was used in sugar processing and for a smelter located near Salida, Colorado. During the 1920s, Colorado Fuel and Iron Company (CF&I) began to exploit the deposit as a source of flux stone for its blast furnace steel operations at Pueblo. The deposit was operated for many years as a captive quarry by CF&I. In 1984, CF&I closed the quarrying operations at Monarch; flux stone was no longer required since the blast furnaces were taken off line in 198 1. In 1994, Colorado Lime Company, a subsidiary of United States Lime and Minerals, Inc. acquired the property. Limestone was mined from the Castle Butte Member of the Leadville Limestone (Lower Missippian). Some high- magnesium dolomite was also mined during WWII from the Redcliff Dolomite Member which directly underlies the Castle Butte. Past production was from both an upper and lower quarry at elevations ranging from 10,000 to 11,000 feet (3,048 m-3,353 m) mean sea level (m.s.1.). The reserves at Monarch quarry are in a dip slope deposit, occupying the northwest slope of Monarch Hill. The structural geology of the deposit is complex on both a region- al and mine scale. The reserves are located on the eastern limb of the Syncline Hill syncline. The beds on this limb of the structure strike to the northeast and dip to the northwest from 30 to 45 degrees. A major reverse fault separates the reserves into an upper and lower deposit. Numerous smaller normal and reverse faults cut the deposit, requiring a flexible mine plan. At the Monarch quarry, the Castle Butte Member con- sists of two stratigraphic units. The Upper unit (Mlu) is a thick-bedded, fine-grained crystalline dolomitic limestone from 0 to 300 feet (0-90 m) thick. The unit generally has an Si02 content of less than 4 percent. A bedded chert horizon and a karst horizon at the base of the unit locally raise the Si02 content as high as 20 percent. The underlying Quarry Stone unit (Mlq) is a light-gray, massive, bedded, calcilutite/micrite limestone from 90 to 130 feet (27-40 m) thick. The Quarry Stone unit is remarkably uniform chemically throughout it's entire thickness. Average analysis is CaC03 - 95 percent, MgC03 - 3.5 percent, and Si02 - 0.5 percent. The Footwall dolomite unit (Mld) of the Redcliff Member of the Leadville Limestone is a dark gray to black, blocky, medium-to-thick-bedded, calcilutite/micrite dolomite from 150 to 180 feet thick (46-55 m). The upper 100 feet (30 m) of the unit is a low-silica facies with an average Si02 content of less than 0.5 percent. MgC03 content is con- sistent at 39.8 percent throughout the upper 50 feet (15 m) of the unit but varies from 15 percent to 39.8 percent in the lower portion (50 to 100 feet [15-30 m]) of the low-silica facies. The lowest portion of the unit, 100 feet (30 m) to base of unit is high in silica and is not considered chemical grade. Current in-place, surface-minable reserves at the quarry are estimated to be 14 million short tons (st) (13 million metric tons [mt]) of limestone and 50 million st (45 million mt) of dolomite. A 1.4 million st (1.3 million mt) stockpile of finely crushed limestone is also present on the property. Colorado Lime is presently processing approximately 2,000 st (1,800 mt) per month from the crushed limestone stockpile. This material is pulverized and sold to underground coal mines for use as rock dust, some of this product is also used for environmental purposes. Limestone mining is scheduled to resume in spring of 2000.

Jan 1, 2001

By Elisa Comis, Jeffrey Peterson, Yama Ebrahimi

Construction of the Northeast Boundary Tunnel (NEBT), the last leg of the Anacostia River Tunnel System on DC Water’s Clean Rivers Project, started in September 2018 and was completed in April 2021. The 26-foot-bore earth pressure balance (EPB) tunnel boring machine (TBM) mined 26,737 feet at elevations between 80 to 160 feet belowground. Approximately 55% of the tunnel was cut through lower predominantly coarse-grained facies identified as the Cretaceous Patuxent Formation (undifferentiated) (PTX), and the remainder was cut through upper predominantly overconsolidated fine-grained plastic material facies identified as the Cretaceous Patapsco/Arundel Formation (P/A). Mixed face conditions were encountered in the transition from the P/A to the PTX and vice versa. This paper reviews the performance of the TBM that mined the NEBT through several unique challenges, including 8,000 feet of tunneling under the heavily developed Rhode Island Avenue corridor, major sensitive structures, cast iron water distribution mains, and other sensitive utilities.

Dec 1, 2022

By T. McCallum, C. Cooper, B. Hutzler

"In copper solvent extraction, managing the quality of the organic phase is a key parameter to ensure optimal physical and metallurgical performance in the plant. Increased throughput as a result of declining ore grades coupled with advances in plant design and practice, resulting in reduced organic losses, has pushed the limits of the status quo with respect to organic quality. Clay treatment of plant and recovered organic at the optimal dosage is critical in maintaining quality, however, achieving the optimal dosage through existing filtration capacity and practice can be difficult. Cytec has developed a process aid that increases efficiency of existing filtration equipment that has been successfully implemented at two commercial SX operations. ACORGA® CB1000 enables higher dosages of clay while allowing for more efficient use of existing filtration capacity. This study analyzes results from commercial trials and demonstrates that improved organic quality and clarity is achievable through optimization of current treatment practices. INTRODUCTION Decreasing ore grades have prompted copper solvent extraction operations to raise PLS flow rates, increasing plant throughput to maintain production1. The ability to process higher flow rates through existing mixer-settlers historically came at the expense of increased entrainments2. However, advances in mixer-settler design, practices and improvements in organic recovery processes have enabled operations to maintain, and in some cases reduce organic losses while achieving higher flow rates through existing equipment. Based on the increased demand on the SX equipment and reduced losses (or more efficient recovery) maintenance of the circuit organic quality through efficient clay treatment is now more important than ever. This paper discusses common industry practices and related issues in organic clay treatment, and presents benefits achieved in commercial operations through the use of ACORGA® CB1000 Clay Binder. IMPROVEMENTS IN DESIGN AND PLANT PRACTICE Mixer-settler design has improved since the first commercial copper SX operation in the late 1960s. Advanced designs in mixer, settler, and settler internals have contributed to reductions in entrainments. For example, improved impeller designs have been reported to decrease organic in aqueous entrainment from the ‘old designs’ of 50-200 ppm3 to as low as 4 – 10 ppm confirmed via diluent and reagent consumptions . Similarly, operations are reporting a 20-50% decrease in reagent consumption when compared to the original design criteria3. Operations have optimized settler internals to increase coalescence and have improved settler operating practices which have been shown to reduce entrainments7. Comparison of the SX world operating data from 1999 and 2007 shows reductions in organic entrainment losses with increases in flow rates."

Jan 1, 2015

By J. Driscoll

After 30 years of success, Newmont Gold Company has temporarily ceased production from the original Carlin Pit. In late 1993, the Carlin East Decline was driven and an extensive underground exploration program was started. Today, Newmont Gold produces refractory ore from the Carlin East underground at the rate of 700 t/d (770 stpd) for an annual production of over 100,000 ounces. Over 70 underground miners enjoy the estimated 6-year mine life at Carlin East. About 70% of the ore at Carlin East is mined by mechanized longhole stoping with delayed cemented backfill. The remaining ore is mined by underhand drift and cemented fill methods.

Jan 1, 1997

By A. I. Johnson

This paper describes," the application, of a modular or building block approach to the analysis, design, and control of complex mineral treating processes. The main purpose of the paper is tutorial, to show the reader how such processes can be modeled using a modern digital computer" and, not to discuss in any detail the results that may be achieved in such studies. It is proposed that, the main techniques be illustrated by reference mainly to the Bayer process for alumina extraction and purification; in cooperation with the Aluminum Company of Canada Ltd. the author and his Colleagues at McMaster University and their students have studied this, process as a means of applying new computer techniques to extractive metallurgical processes. The plant described was studied by the author and his colleagues as a senior undergraduate project in cooperation with the Aluminum Company of Canada. It is one of several studies that have been carried out with Canadian industry. (1)

Jan 1, 1972

By M. R. Carter

The Rochester Mining District is located some twenty-five miles NE of Lovelock, Nevada. The District was discovered and named in the 1860's by prospectors from Rochester, New York. For a number of years, they worked Rochester Canyon, sinking shafts and inclines and making open cuts. After reaching a depth of approximately eighty feet, the miners tapped an underground channel and were driven from these workings by a strong flow of water leaving pumps in the shaft and barely escaping with their lives. With the Rochester workings no longer accessible, the miners went to the southeast and established the Relief Mining District. About 1881, gold was found in the gravel at the mouth of American Canyon, to the east of Rochester. These placers were worked until 1895, first by the Americans who reportedly took out $1 000 000, and later by the Chinese who mined the gravel with great skill. It was estimated that the Chinese took out as much as $10 000 000.

Jan 1, 1987

By E. R. Drevdahl

It has been suggested that we at the University of Arizona present a paper covering the origin, philosophy, and results of the College of Mines program in the field of computers and operations research. I have worked with the program since its beginning, and I will try to outline the developments as they have taken place. The formal development of the educational and research program in the field of Operations Research and Computer Applications at the College of Mines, University of Arizona, began in early 1957. During the year, the University offered its first formal instruction in computer programming. This was my first introduction to computers, and it did not take long to realize that this new tool had a potential that could be profitably utilized by the mining industry. In March 6f 1957, the University Computing Center began operations with its IBM 650 computer. This machine was the only computer of this size in the local area at this time, The first programming effort was in machine language and the programming cost could only be justified for repetitive-type of problems. The progress in the computer field moved very rapidly and with the development of the many compiler and assembly programs and the addition of sub routines to the computer library, the scope of problems that could profitably be investigated by computers expanded rapidly.

Jan 1, 1963

By Patrick B. Kenny

Generally speaking, it is safe to address this conference as a conclave of Engineers, Owners' Agents, Governmental Representatives, and Contractors. As a group, we have assembled here to learn of our compatriots engaged in similiar underground operations throughout the United States and the World. We are here to learn of improved methods, higher technology, and better management. Through the acquisition of this knowledge, we each hope we can improve our own particular services, products and projects. This session is dedicated to a discussion of "Costs". The most apparent reason for a discussion of costs at this level is to expose subjects affecting costs and propose methods to reduce them. From that premise a contractor can identify three areas of discussion: design considerations, contract considerations, and governmental considerations. A fourth area of consideration is an introspective view of the contractor's role in the design construct process. Unnecessary costs and risks attributable to these areas are contributing excessively to ever increasing project and system costs. DESIGN CONSIDERATIONS On April 20, 1977 the Metropolitan Sanitary District of Greater Chicago accepted proposals for the Tunnel and Reservoir Plan on Contract A and Contract B. This letting called for construction of over 33 km (21 miles) of the Mainstream Tunnel bored at 9.75 m (32 ft) to 10.67 m (35 ft.) in diameter. Also included were all the appurtenant collecting and regulating structures. The proposal allowed the

Jan 1, 1979

By P. A. Roberts

A proposal for a modified in situ leaching method for extracting gold from oxidized gold ores using a non-cyanide lixiviant is described. A non-cyanide lixiviant is suggested because of the obvious concerns posed by injecting cyanide-bearing solutions into the subsurface. Oxidized gold ores were chosen as a focus because earlier research on the use of sodium thiosulfate as a lixiviant under anaerobic conditions indicated that the presence of pyrite led to rapid thiosulfate breakdown. A reconnaissance research program involving ore characterization and hydrometallurgical test work on samples from four Australian ore deposits and preliminary reactive transport modeling studies was carried out. This work showed that lixiviant-oxidant combinations of sodium thiosulfate and ferric EDTA and iodide and iodine are both capable of extracting high percentages of accessible gold from the selected samples in bottle roll tests under anaerobic conditions. The ore characterization and reactive transport studies suggested that both physical and chemical methods of permeability enhancement may be required to lift bulk permeability and the availability of gold for dissolution to sufficiently high levels to obtain adequate gold recoveries. Assuming that such methods prove to be both necessary and economically viable, the mining method would no longer be regarded as simple in situ leaching. Therefore, the term ?in-place leaching? has been adopted for the proposed gold extraction system.

Jan 1, 2010

By Thomas Novak, Sampurna Arya

Controlling dust generation and keeping it below permissible limits to meet federal dust standards at the working face of a room-and-pillar coal mine is a challenge for a mine operator. With the recent changes in federal dust regulations requiring lower worker exposure, maintaining compliance has become increasingly difficult. The current most effective practice of dust control at a continuous miner face in an underground mine is the use of a flooded-bed scrubber. A study carried out by the U.S National Institute for Occupational Safety and Health (NIOSH) indicated that a flooded-bed scrubber could achieve cleaning efficiencies between 58 and 90 percent. But the operation of such a system is maintenance intensive. The flooded-bed scrubber screen becomes clogged with dust particles and requires frequent cleaning to maintain performance. However, the dust control issue is not solely a mining-industry problem. Other industries face similar issues. The University of Kentucky collaborated with Toyota Motor Manufacturing on the development of a novel wet scrubber, called the vortecone scrubber, for capturing over-sprayed paint particles in automotive paint booths. The vortecone scrubber achieved a cleaning efficiency of 99 percent and required minimal maintenance. This study aims to assess the ability of this vortecone scrubber to capture respirable dust in an underground coal mine. The paper presents the results of computational fluid dynamics (CFD) modeling of this vortecone scrubber. It discusses the effects of air quantity and dust particle size on the performance of the scrubber. 

By D. M. Fritz

Environmental experts face large and rapidly-increasing volumes of raw data obtained from environmental monitoring stations. These professionals must compile and analyze the data in a systematic manner to cost-effectively understand and minimize the impacts of mining. The shift toward desktop computing, combined with the downsizing of company staffs, has now more than ever created a demand for a modern, PC-based application for the storage, retrieval, analysis and presentation of environmental data. This paper discusses the general requirements of such a system, and points out specific ways in which such industry-specific software can provide convenient and useful access to the data. The software used to illustrate these features is the HydroDat program, developed by Western Water Consultants, Inc.

Jan 1, 1996

By T. Robyn

The Bolivar Cu-Zn skarn deposit in the Piedras Verdes mining district of Chihuahua is one of many base and precious metal deposits in the north-northwest trending Sierra Madre Belt extending across the states of Chihuahua, Durango and Sonora in northwestern Mexico. The information presented here is drawn from two papers on the Bolivar property1,4 plus new information. Historical mining and exploration for polymetallic Cu-Zn-Pb-Ag-Au deposits in the Sierra Madre Belt dates to Spanish Colonial days. Access to the Bolivar Property (Figure 1) is by paved road (approximately 305 km southwest from Chihuahua) and approximately 80 km by all-season gravel roads to the villages of Cieneguita (population ~1,000) and Piedras Verdes (population ~500) adjacent to the property. [ ] The Bolivar property comprises an old Cu-Zn producer (the Bolivar Mine), exploration concessions adjacent to the Bolivar Mine, and a new camp at the mine that supports mining, exploration and maintenance. From 1980 to 2000, former operators extracted approximately 300,000 tonnes of ore that was hand sorted to an average grade of 5-6% Cu and 25-30% Zn. From 2005-2010, Dia Bras produced from the mine just over 600,000 tonnes at an average grade of 1.7% Cu and 8.6% Zn. Dia Bras transported mineralized rock 275 km by truck and rail to its Malpaso mill, located about 30 km west of Cuauhtémoc in central Chihuahua, from 2005 until October 2011 when the new Piedras Verde mill was commissioned only 5 km from the mine. (Note: the Company cannot use the term ?ore? because it has never completed a feasibility study.)

Jan 1, 2012

By W. Robert Power

Dimension stone includes a wide variety of natural materials that are put to an equally wide variety of uses. It is possible to classify dimension stone according to the end use to which the stone is put or according to the lithology of the stone. Both schemes are used by the United States Bureau of Mines in the annual Minerals Yearbook. The 1969 Yearbook lists 15 specific uses and has additional miscellaneous catagories. The same Yearbook lists five specific rock types or lithologies, and also includes a miscellaneous category. In a short presentation it would hardly be possible to list and define all these categories, much less discuss the evaluation of deposits with regard to all possible combinations. Besides, I am only slightly familiar with some of the uses and their requirements. I have therefore chosen to limit my remarks to some special problems in evaluating dimension stone that is to be cut and finished to specific sizes, tolerances, and finishes for use in buildings and some monuments. This use class is called cut stone in the Minerals Yearbook. In terms of dollar value it is the largest single use category. In 1969 the dollar value of cut stone was $29,122,000 which is more than twice the value of the next largest category. For those of you who are interested in other use applications of dimension stone I suggest that you start with recent articles by Bowles (1960), Currier (1960), and Barton (1968).

Jan 1, 1972

By C. Brown, N. Rayyan, T. H. Dubaniewicz

Lithium-Ion batteries (LIBs) have the potential to go into thermal runaway which introduces a new ignition source in hazardous environments such as gassy underground mines that may contain methane in the surrounding air. Researchers from the National Institute for Occupational Safety and Health (NIOSH) used an accelerating rate calorimeter (ARC) to induce thermal runaway in individual lithium-titanium-oxide (LTO) and lithium-nickel-cobalt-aluminum-oxide (NCA) LIB cells within a sealed enclosure with either no methane, a lean, a stoichiometric, or a rich methane-air mixture in the surrounding canister to determine if these LIB types would ignite the methane, causing an additive effect on overpressures. Canister pressures and maximum temperatures reached by the cells, surrounding air, and exhausted gases were measured in this study and remained consistent with varying methane concentrations.

Feb 1, 2023

By J. J. Zimmerman

Over-exposure to noise remains a widespread, serious health hazard in the U.S. mining industries. Most other categories of illnesses and injuries associated with mining have improved, with the exception of hearing loss. Mine Safety and Health Administration (MSHA) coal noise data from 2000-2004 show that the continuous mining machine is first among all equipment with 35% of the noise overexposures. Joy Mining Machinery, in collaboration with the National Institute for Occupational Safety and Health (NIOSH), is conducting research to reduce noise generated by continuous mining machines. This paper describes a ?JOY Designed for Noise Reduction? (JOY-DNR; Patent Pending) tail section as a noise control for reducing the noise overexposures of continuous mining machine operators. Underground results show a 45% and 65% noise exposure reduction for the operator when compared to a standard machine. Utilizing this newly developed noise control, along with previously proven controls, will provide continuous mining machine operators an opportunity to be within the MSHA-Permissible Exposure Limit (MSHA-PEL).

Jan 1, 2010