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By Roger J. Morrell

Bureau of Mines laboratory experiments with reduced scale cutter and cutter forces were performed to (1) define the fundamental relationships governing disk cutter performance and (2) to develop a method of predicting disk cutter performance in soft, medium, and hard rocks. The rock cutting experiments were performed in four igneous and metamorphic rocks that ranged in compressive strength from 38,000 to 67,000 psi. A special testing machine called a linear cutter apparatus (LCA) was used to load and traverse a free rolling disk cutter across a smooth rock surface. Each pass of the disk produced a single crater, and runs were spaced to avoid breakage between craters. During each run the normal and tangential cutter forces were measured and recorded. The soft and medium rock data were obtained from previous Bureau experiments with disk cutters. Crater depth, tangential cutter force, crater volume, specific energy versus normal cutter force, and crater width versus depth are defined within this study. With the use of standard physical properties, performance prediction equations were developed using stepwise linear regression analysis techniques. A method of using these prediction equations to calculate the boring rate, the cutter spacing, and the torque and energy requirements of a full-scale boring machine was also developed.

Jan 1, 1974

By Paul C. Schmall, Thomas Tuozzolo, Arthur B. Corwin

The Lenox Avenue Reconstruction Project involved the excavation and replacement of 750 m (2,500 ft) of deteriorated subway invert concrete, 5 to 7 m (15 to20 ft) below water table in very permeable ground. The Replacement work was done over an 8 month period, while maintaining track service through this subway section. The project was dewatered with a single 125 l/s (2,000 gpm) wellpoint system,750 m (2,500 ft) in length, which was installed from inside the active tunnel structure and configured to coexist in the subway tunnel with operating trains as well as the construction activities. A thin diaphragm jet grout wall was utilized on one end of the site to cut off the flow of water across a difficult geological interface that was situated immediately below the tunnel invert. The thin diaphragm jet grout wall permitted the large 116th Street Station area to be dewatered completely with well points from outside of the excavation.

Jan 1, 2001

In September, a fleet of 363-t (400-st) Liebherr trucks became operational in Brazil and have already begun moving iron ore in Para state. Prior to the arrival of the the trucks the Brazilian fleet relied on trucks up to 218 t (240 st). With the addition of the 363 t (400 st) trucks, the fleet has since experienced the high productivity offered by Liebherr T 282 B trucks.

Jan 1, 2010

By M. Martins

This work presents and discusses the influence of the surface tension (gLV) of methanol/water mixtures on the flotation response of apatite versus gangue minerals conditioned with flotation reagents (75 g/t cornstarch and 100 g/t Berol 867) at pH 10.6. Berol 867 is a collector composed of sodium alkyl sarcosinate plus nonionic surfactant. The highest Schulz efficiency of separation (recovery of apatite minus recovery of gangue) was achieved at ?51.0 mN/m. The critical surface tension of wettability (gC) of apatite was found to occur at 34.7 mN/m when determined by means of gamma flotation experiments, and it was 33.9 mN/m when determined by Zisman?s approach.

Jan 1, 2009

By Zoltan F. Oszter

The design of belt conveyors is a well-known procedure and related formulae can be found in any handbook dealing with materials handling. Belting and conveying equipment manufacturer's catalogues and design manuals offer a wide range of detailed information which can be applied to most of our conveying problems. The aim of this paper, however, is to investigate the design of a specific type of belt conveyor, namely the long horizontal, or nearly horizontal, type. (The undulating type, with moderate lifts and drops, can also be included in this category.) Most of the long overland conveyors carrying ore from pit to processing plant, or those carrying over-burden to the disposal area, fit this description. A critical appraisal will show that reasonably accurate results can be obtained when tl1e familiar horse-power formulae are applied to this type of conveyor. The progress and new developments in the design of belt conveyors, which have resulted from the extensive research done in the past decade, will also be explored.

Jan 1, 1962

By Jun Lu, Mark Van Dyke, Daniel W. H. Su, Greg Hasenfus

"This paper presents the geologic and ground control challenges that were encountered by CONSOL Energy’s mining operations in southwestern Pennsylvania. A sandstone-to-limestone geology transition was encountered by Mine A, where the primary 8-foot bolts were anchored in claystone. Upon experiencing roof sags and a roof fall in the return entry, 6-foot high-tension, fully-grouted primary bolts were employed along with 16-foot center cable bolts at every other strap to improve beam building and to ensure proper anchorage into the competent limestone. No longwall delay was reported within this geologic transition zone, although there was some difficulty in maintaining an open #2 entry airway behind the longwall face.The geologic encounter in Mine B was more complex, where fluvial deposits of massive sandstone channels, shale channels and pyritic-rich, green claystones were encountered on both sides of the mains, and which impacted both development and longwall ground control. In particular, poor transitional roof areas near the edges of the sandstone and shale channels often posed significant ground control challenges. In addition, hydraulic fracturing was sometimes utilized to enhance caving of massive sandstone behind the shields to relieve pressure at the face. Longwall face conditions and advance rates were documented to illustrate the effects of sandstone channels, shale channels, and green claystones on safety and productivity and to demonstrate the effectiveness of the hydraulic fracturing.Shale channels, slickensided zones, laminated roof zones, soft floor, and a regional syncline were encountered in Mine C, the combination of which posed unique ground control challenges during both development and longwall mining. The presence of soft floor, coupled with the presence of thick floor coal and deep cover, resulted in headgate convergence during retreat of the first right-hand longwall panel. Two-piece 8-foot bolts were sometimes observed to fail at the coupler within the laminated roof zone, and 6-foot, 1-piece, fully-grouted point-anchor bolts were employed as the primary bolts thereafter."

Jan 1, 2015

By Ronald D. Hill, Elmore C. Grim

Coal-haul and mine access roads are defined as any road constructed, improved or used by the operator (except public roads) that ends at the pit or bench. These roads constitute approximately 10% of the total area directly disturbed by the surface mining operation(l). In some cases, the land disturbed by haul roads exceeds the area included in the mining operation. Studies (2 and 3) of the U. S. Forest Service in eastern Kentucky show that typical contour mining roads exhibit poor alignment, excessive grades, insufficient strength and durability, and poor drainage. Mine roads in other Appalachian- States, particularly where contour mining is practiced, appear much the same as those in Kentucky. Access roads(4) were also found to be a large source of sediment. It is possible that of the sediment that finds its way into the streams as much (or even more) originates from the haul roads as from the mining operation. Most roads are built as cheaply as possible, and good road-building design and practice are ignored. Maintenance schedules are generally inadequate, and upon completion of mining, haul roads are usually abandoned, with little or no attempt made to bed them down(5 ) . Such roads deteriorate very rapidly (Figure 68). Area mining, which is practiced in flat to gently rolling terrain, presents fewer haul road related environmental problems. These roads through necessity are generally well engineered because of the heavy equipment using them, such as 240 ton (217 metric ton) haul trucks. They must have wide beds, good alignment, and adequate drainage to permit coal haulers to run at top speed during all seasons of the year. Excessive dust can be a public nuisance and a driving hazard, and it is hard on equipment. Calcium chloride and sodium chloride have proven to be effective materials for controlling dust. Two applications during the summer when the ground surface is moist at the rate of 1/2 pound per square yard (.26 kilograms per square meter) (3 1 have been suggested. Th4 most common procedure is to keep the roads wet by using water trucks. Sediment that reaches the streams can be traced to one or more of the following five basic phases of haul-road life:

Jan 1, 1974

By K. -H. Lux, Z. Hou

ABSTRACT: It is well known in underground mining and waste disposal that the development of excavation damaged zones (EDZ), and thus, hydraulic pathways, is closely related to the excess in the corresponding damage boundary (= long-term strength) of the rock mass and the resulting damage. By integrating short-term and long-term strength, dilatancy, damage and healing into the newly extended Hou/Lux constitutive model for rock salt, it is possible to treat the tertiary creep, to identify the EDZ around underground facilities and to predict the time-dependent development of the EDZ in rock salt. Under in-situ conditions, the EDZ of a 37-year-old drift at the Sondershausen salt mine and the EDZ around a drift dam in rock salt are numerically examined. The numerical analysis gives satisfactory results. RÉSUMÉ: Dans les exploitations minières et le stockage souterrain des déchets, le développement des zones endommagées et fracturées (EDZ – excavation damaged zone), créant des chemins préférentiels pour écoulement, est étroitement lié au contexte géotechnique et à la méthode d’excavation. En intégrant la résistance court et long terme, la dilatance, l’endommagement et le colmatage, le nouveau modèle rhéologique Hou/Lux pour le sel gemme est capable de traiter le fluage tertiaire, d’évaluer l’extension de l’EDZ et de prédire l’évolution de EDZ dans temps autour des ouvrages creusés dans le sel gemme. L’EDZ d’une galerie datée de 37 ans dans la mine de sel de Sondershausen et les EDZ autour de barrage des galeries dans un sel gemme ont été modélisées. Les résultats numériques fournissent des résultats satisfaisants. ZUSAMENFASSUNG: Bekanntlich ist die Entstehung von Auflockerungszonen und damit hydraulischen Wegsamkeiten in der unmittelbaren Umgebung um bergmännische Hohlräume mit der Überschreitung der entsprechenden Schädigungsgrenze eng verbunden. Unter Berücksichtigung der Bruchfestigkeit, Schädigungsgrenze, Dilatanz, Schädigung und Verheilung kann das Stoffmodell Hou/Lux das Verhalten des tertiären Kriechens beschreiben, die Auflockerungszone im Salzgebirge ermitteln und ihre zeitabhängige Ausdehnung vorausberechnen. Mit diesem Stoffmodell werden die Auflockerungszonen einer 37jährigen Strecke in der Salzgrube Sondershausen und die Auflockerungszonen um ein exemplarisches Abdichtungsbauwerk im Salzgebirge numerisch untersucht. Dabei werden zufriedenstellende Berechnungsergebnisse erzielt.

Jan 1, 2003

By J. G. Pippenger

The mining industry has been Australia?s major economic driver over the past decade, contributing 8% to Australia?s Gross Domestic Product and 26% of Australian Stock Exchange Market capitalisation. Australia is the world's leading exporter in coal, iron ore, alumina, lead and zinc; and second largest in gold and uranium. While driving the economy, this resource boom has also created a demand for professional and operating talent that has far outstripped the capacity of Australia?s 21 million residents. I moved to Australia some 10 years ago and have not looked back. This unique island continent with its mix of Indigenous and diverse immigrants ? many still proud of their convict ancestry ? has offered life long memories both professionally and personally.

Jan 1, 2011

By J. Nakayama

Construction of foundation piles or diaphragm walls through rocky or boulder containing formations has been long-standing difficulty. It has been widely understood that the down-the-hole hammer is the most capable mechanical means but is restricted in drilling diameter by the unavailability of drillhead sufficiently large diameter and the difficulty of disposal of cuttings. A great number of submersible motordrills have been used for the construction of cast-in-place piles and diaphragm walls and the reverse circulation system employed has demonstrated its advantage of the prompt removal of cuttings. The development of multi-head down-the-hole hammer drill combined with reverse circulation system presents a powerful engineering choice for those "hard-to-drill" ground formations. This paper will introduce the features of the system and some actual operation results in the foundation engineering through those hard rocky ground formation in some countries.

Jan 1, 1989

By Mary Cocklan-Vendl

Regulatory processes associated with development of a world class lead-zinc mine, Red Dog Mine, in northwestern Alaska were reviewed and evaluated. Informal interviews with key project personnel, consultants, and agency field and permitting specialists provided perspective on the regulatory successes and failures of the project. Due to potential impacts to air quality, water quality, wetlands, and National Park lands, an Environmental Impact Statement was required. By developing a comprehensive baseline of information on the existing environment to aid in minimizing impacts during project siting/design and through regular coordination of evolving project plans with regulatory agencies, the mine developers were able to acquire necessary permits in a timely and cost effective manner. The only major exceptions occurred when inadequate information was collected on dispersal of airborne particulates, rates of surface water run-off, and groundwater quality. These deficiencies resulted in the need for design changes, unscheduled construction, additional environmental monitoring costs, and delays in issuance of the NPDES permit.

Jan 1, 1992

The Bureau of Mines is the engineering arm of the Government for mineral resources. Its mission is to carry out laboratory and field studies that will assure the wise and effective development and use of our Nation's minerals, fuels, and underground domain in order to preserve the security and enhance the welfare of our people. Specifically, studies are directed to the means by which current and emerging demands may be met, the real cost of such achievements, and the assessment of related social and economic factors. Ways are sought to fulfill our material needs in a manner that minimizes occupational hazards to workers in the industry, reduces waste, and ensures that mineral raw materials are supplied and mineral-based products are used and are disposed of efficiently, without objectionable social and environmental costs. The headquarters of the Bureau of Mines is located in Washington, D.C. The Bureau's research and development program, however, is conducted at 19 research centers and laboratories located throughout the United States.

Jan 1, 1971

By Charles E. Whieldon

Data on the oilfields in Mahoning, Columbiana, Carroll, Jefferson, and Harrison Counties, Ohio, were collected from scattered sources and compiled to make the information readily available to operators who may be interested in conducting secondary-recovery operations in the area. General geology, oil production, oil-productive acreage, core data, reservoir calculations by townships, and miscellaneous data and reference material are presented.

Jan 1, 1965

By A. V. Shroff

The Indian Standards code of practice for design and construction of underreamed piles contains provision for installing such piles in expasive soils. In recent years, a large amount of research work has been carried out in the analysis, design, construction and performance of underreamed piles in expansive soils. This paper suggests that the results of this research field tests should be included in the code. Various additions and modifications as well as deletions that should be incorporated in the code are discussed.

Jan 1, 1996

This chapter presents an overview of fatal and nonfatal injuries reported to MSHA during 1986-1995. Reportable injuries follow the criteria for reporting specified in 30 CFR 50. These criteria are listed in appendix A. The data used for these analyses came from the MSHA accident, injury, and illness data closeout files for the years 1986-1995. The MSHA data are described in appendix A and methods used in data analysis in appendix B. There may be slight discrepancies between the figures presented here and other presentations of MSHA data for the following reasons: (1) injuries to nonemployees have been excluded from analysis; and (2) injuries identified by MSHA after the files were closed out are not included. Within the MSHA data, there are differences in reporting requirements for operators and contractors. Contractors are required to report only those injuries that occur during certain categories of work (described in appendix A). For this reason, data on injuries among employees of operators and contractors in the MSHA database should not be considered directly comparable. As discussed in the "Introduction," the MSHA data on fatal injuries differ from the CFOI data (chapter 1) because of varying definitions used for the mining industry. As compared to the CFOI data, MSHA data exclude injuries that occurred off of mine property and include injuries occurring at mills and processing plants on mine property. Tables 4-1 through 4-9 and figure 4-1 provide comparisons of injury frequencies and rates among the commodities. These comparisons are followed by sections 4A through 4E, which provide more detailed tables and figures for each commodity separately. The method used to calculate injury rates is described in appendix B. Since denominator data for occupations (lob titles) were available for 1986 only, estimates of rates by occupation for the entire 10 year period are based on extrapolation from 1986 data. For this reason, estimates of injury by occupation should be interpreted with caution. Fatal Injuries A total of 1,078 fatal on-the-job injuries were reported to MSHA during the 10-year period 1986- 1995. The average annual fatal injury rate for all commodities combined during this period was 30.9 per 100,000 full-time equivalent workers. Mine operators accounted for 908 (84%) of the fatalities and had an average annual fatal injury rate of 28.2 per 100,000. While mine contractors comprised only 16% (n = 170) of the total number of fatalities, their average annual fatal injury rate was 2.3 times higher than that of mine operators (65.0 per 100,000). Table 4-1 presents the number and rates of fatal injuries by commodity for operators and contractors. Contractors in metal, nonmetal, stone, and sand and gravel are grouped together, since MSHA data on employment were not available for rate calculations for these commodities separately. The highest average annual fatality rate for the period, 66.5 per 100,000, occurred among metal and nonmetallic mineral mining contractors, followed closely by coal contractors (63.1 per 100,000). Among mine operators, the highest average annual fatal injury rate was in coal (38.9 per 100,000); the lowest was in nonmetal (14.3 per 100,000). Table 4-2 shows the average annual fatal injury rate by type of operation for each commodity for mine operators only. Of commodities with underground mines, all except stone had higher fatality rates at underground than at surface operations of these mines. The highest fatality rate for any operation occurred in surface operations at underground stone mines (124.5 fatal injuries per 100,000 workers). Stone had the second highest fatality rate for underground operations at underground mines (77.9 per 100,000). The highest rate for underground operations at underground mines occurred in metal (87.6 per 100,000). Table 4-3 shows the number and rate of fatal injuries by U.S. Bureau of the Census occupational groups (described in appendix D) for the 10 occupation-commodity groups with the highest fatal injury rates. These data should be interpreted with caution because the denominator used in calculating the rates was based on an extrapolation from data for the year 1986 only, as described in appendix B. Extractive occupations are represented in this group for three commodities: coal, metal, and sand and gravel. Construction trades are included for coal, sand and gravel, and nonmetal. The distribution of fatal injuries by commodity and work activity for mine operators is presented in table 4-4. A description of the work activity categories is in appendix C. Overall, the leading work activity at the time of injury was using or operating tools and machinery (26.4%) followed by constructing, repairing, and cleaning (24.0%), vehicular operations (18.8%), and materials handling (12.6%). The distribution varied by commodity. The largest percentage of fatal injuries occurred while operating tools and machinery in both coal and stone; during vehicular operations in metal; and during constructing, repairing, and cleaning activities in nonmetal and sand and gravel. Table 4-5 shows the distribution of fatal injuries by commodity and MSHA accident classification for mine operators. A description of the MSHA accident classifications appears in appendix E. The largest proportion of injuries overall occurred during powered haulage (28.5%). The

Jan 5, 2000

By Eric E. Cather

A mineral survey of a portion of the Lake Eleanor RARE II area (No. 5807), Trinity County, California, was done by the U.S. Bureau of Mines and U.S. Geological Survey (USGS). Approximately 8,650 acres (3,500 ha) of the Lake Eleanor RARE II area not examined for this report had been previously investigated by U.S. Bureau of Mines and U.S. Geological Survey personnel and published as part of USGS Bulletin 1371-B, (Hotz, 1972) Mineral Resources of the Salmon-Trinity Alps Primitive Area, California. The report showed that the section included in the rake Eleanor RARE II area contained no metallic mineral resources. Geochemical sampling indicated that the Lake Eleanor RARE II area contains no potentially important mineral resources. About 4,650 acres (1,880 ha) of the eastern part of Lake Eleanor RARE II area were examined for this report. The Bureau of Mines was responsible for detailed examination and sampling of mines, prospects, and mineralized zones; the Geological Survey conducted geological, geochemical, and geophysical studies of the area. This area is underlain mainly by granitic rock and serpentinite.

Jan 1, 1981

By Ronald W. Stingelin

The geology of the roof of the Pittsburgh coal bed was studied and mapped in nine contiguous counties containing the bulk of the remaining reserves of this coal bed in the northern Appalachian Coal Basin. Drill core records from Belmont and Monroe counties, Ohio, Washington and Greene counties Pennsylvania, and Ohio, Marshall, Wetzel, Monongalia, and Marion counties, West Virginia provided the data for twelve computer generated regional geologic variable maps. Four of these geologic variables (overburden thickness, vertical distance to the rider coal, lithology at the five foot horizon above the roof of the mineable Pittsburgh seam, and the number of lithologic changes within the 30 foot interval above the roof of the mineable Pittsburgh seam) were used to estimate the risk of potential roof falls by a methological scheme developed during this study. A hazard zone risk map was developed showing a generalized regional trend of increasing risk from west to east across the basin. Mapping of individual geologic variables and mapping of hazard risk can be done at any scale. The accuracy of the mapping is primarily dependent on the density of the drill core records. Geologic feature maps and the hazard risk map contained in this report are reduced (1 :500,000 scale) versions of the larger scale (1 :62,500) maps prepared for the Bureau of Mines as map folios.

Jan 1, 1979

By Martin Stoklossa

Surface mining operations typically require run-of-mine material to be sized for further processing. In-pit crushing facilities serve this need, as stationary, semi-mobile or fully mobile units. Although in particular fully mobile crushing facilities have been in use for over half of a century, other surface mining techniques have typically been implemented. However, with increasing operating costs in truck and shovel operations, and other economic considerations, mobile crushing plants are increasingly a viable option. The operational and economical parameters in relation to the optimal surface mining equipment selection will be reviewed. The role of the mobile crushing technology within the continuous vs. noncontinuous surface mining operation and basis for mine planning are also discussed. Current applications and respective case studies will be reviewed. Key performance indicators will be presented. These performance parameters can be viewed as a tool to aid in the equipment selection process. The future direction for further research and development in mobile crushing facilities will also be presented.

May 1, 2008

By Gary L. Stecklein

This final report delineates the findings of the test programs, simulations, and analyses performed to determine the requirements for the effective application of berms and guardrails as truck restraint systems for elevated mine roadways. Included arts criterion for effective vehicle restraint for guardrail applications and recommendations for berm applications based on scale model tests and computer simulations. Full scale haulage vehicle-berm interaction field tests were performed to correlate the results of these model tests and computer simulations. Recommendations for the construction of berms were made on the basis of tests of berm bearing strength, response of the vehicle to different berms, and predictions based on the obtained correlation

Jan 1, 1981