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By Timothy C. Richmond

The Stillwater District is located in south central Montana approximately 75 miles southwest of Billings, the state's largest city. It lies along the northeast front of the Beartooth Mountains and is within the boundaries of the Custer and Gelatin National Forests. The district contains some of the nation's most spectacular mountain scenery. Montana's highest peaks, including 12,799 foot Granite Peak, rise a few miles south of the area. Much of the district is located on a gently undulating plateau which averages 8500 ft. above sea level, broken by hills up to 10,000 feet and slashed by glacially carved canyons, some of which are more than 3,000 feet deep.(Fig. 1) Immediately to the north and east, the land falls away to the Great Plains, stretching unbroken to the Mississippi River. Two major tributaries of the Yellowstone River, the Stillwater and Boulder Rivers, traverse the area and several large streams originate in the district itself. Access to the high mountain country and the adjoining Beartooth Primitive Area is restricted to a few horse and jeep trails continuing from the terminus of improved roads in the bottom of the Stillwater and Boulder Valleys. Hunters, fishermen and cabin owners make intensive use of the area along its improved transportation routes, but hikers seldom venture more than three miles beyond the end of the roads. People from the Billings area are the most frequent visitors.

Jan 1, 1974

By Felicia F. Peng

In operation of column flotation of fine coal, the smaller bubbles are required to effectively recovery of fine hydrophobic particles. However, smaller size bubbles alone does not ensure an efficient flotation for fine particles. The sufficient available bubble surface area per unit column are essential for effective column flotation. The experiments are conducted in a lab-scale column using two different bubble size distributions and three different particle size distributions for flotation of Pittsburgh No.8 seam coal. The interaction between particle size, aeration rate, feed rate and wash water addition are examined in this investigation to establish the optimal operation conditions for flotation of fine coal. Despite of wide range of operation conditions used in this study, it is found that the experimental data fall in a single characteristic recovery-ash curve for a given bubble size distribution and particle size distribution. The major parameters affect the flotation performance points along -the characteristic recovery-ash curves are aeration rate/frother dosage, feed rate and wash water rate-.

Jan 1, 1994

By Roscoe W. Stensrud

The Marcona Corporation was established in 1965 to consolidate the ownership and management of the Marcona group operations. This company, with headquarters in San Francisco, has the following principal operating subsidiaries: Marcona Mining Company, formed in 1953, conducts iron ore mining, beneficiation and pelletizing operations in Peru. Cia. San Juan S.A., Panama, which contracts for sale and delivery of iron ore from the Marcona operation in Peru and from Mount Goldsworthy in Western Australia. Sari Juan Carriers, Ltd., a subsidiary of Cia. San Juan which owns and charters vessels for the bulk ocean transportation of iron ore, petroleum products, coking coal, slurry, salt and other commodities.

Jan 1, 1968

By Scott Brien, O&apos

Cyclones have become standard unit operations in mineral processing for both dewatering mineral slurries and for making separations at given particle sizes. Conventional cyclones are normally able to make moderately sharp cuts. However, the limited ability to control water flow out of the apex means that cyclones have difficulty handling fluctuations in feed. Underflow-regulated cyclones are cyclones with a rubber boot attached to the underflow. This boot acts as a non-return valve and restricts flow out of the apex of a cyclone. Normally, this type of restriction on a cyclone causes severe difficulties in cyclone operation. However, by adding a siphon arm to the overflow, water flow can be controlled. The siphon arm creates a vacuum that reduces or eliminates the air core, permitting better control of the ratio of water flow out of the overflow and underflow. A Linatex-developed underflow-regulated cyclone was compared to a conventional cyclone for its ability to dewater a sand slurry. The underflow-regulated cyclone produced slurries with solids contents as high as 80% in the underflow. Conventional cyclones produced lower solids content in the underflow under similar conditions.

Jan 1, 1997

By P. L. Yorio, D. R. Willmer

"The current paper presents the results of a study designed to explore the types of practices that are fundamentally important to developing and maintaining comprehensive risk-based health and safety management systems (HSMS) in mining organizations. Eighteen practicing health and safety (H&S) executives, managers, and professionals from a variety of mining commodities were asked to assess the fundamental importance of 20 distinct elements and 133 different practices assembled from a review of several HSMS consensus standards. The research approach assumes that developing and maintaining a robust HSMS requires unwavering attention to activities designed to either: 1) directly contribute to a risk management system’s plan-do-check-act cycle; or 2) build an organization’s internal infrastructure without which the cycle cannot be sustained. The results of this study suggest that the following areas require consistent focus and attention: Leadership Development; Accountability; Knowledge, Skills, and Abilities Development; System Coordination; Culture Enhancement; Behavior Optimization; and Risk Management Studies. Each element and its corresponding top-ranked and top-rated practices are discussed.INTRODUCTION Since the time of the Industrial Revolution, occupational health and safety (H&S) management has been a topic of practitioner thought and academic inquiry (1). In the U.S., decades of regulation and research have resulted in a surplus of prescriptive information (techniques, tools, approaches, standards, programs, practices, policies, etc.). With an abundance of such information, a simple H&S solution to address a problem in the U.S. mining industry may seem straightforward. Counter to this assertion, however, some evidence suggests that the abundance of information may create complexity and cause confusion in the minds of organizational leaders and H&S managers, ultimately discouraging the voluntary pursuit of a sound approach (2). In line with this perspective, in 2006 the U.S. National Mining Association (NMA) formed an independent commission to examine H&S management issues within the mining industry. The findings of the commission called for the mining industry to adopt a risk-based management paradigm. In the presentation of its findings, the commission stated that “…every mine should employ a sound risk-analysis process, should conduct a risk analysis, and should develop a management plan to address significant hazards identified by the analysis” (3). Grounded in the well-known plan-do-check-act cycle, the recommended risk management system allows for mines to ground strategic management choices in their mine-specific hazards and risk profiles"

Jan 1, 2015

By Daniel W. H. Su

The ability to predict the effects of longwall mining on topography and surface structures is important for any coal company in making permit applications and anticipating potential mining problems. The sophisticated finite element model described and evaluated in this paper is based upon five years of underground and surface observations and evolutionary development of modeling techniques and attributes. The model provides a very powerful tool to address subsidence and other ground control questions. The model can be used to calculate post-mining stress and strain conditions at any horizon between the mine and the ground surface. This holds the promise of assisting in the prediction of mining-related hydrological effects.

Jan 1, 1986

By I. E. Odom

A study was made of the physical and chemical nature of silica minerals found as natural impurities in bentonites and montmorillonitic Fuller&apos;s earth clay products as well as in <10 micron dust from eight processing plants. The results show that the silica minerals present in these clay materials are totally encapsulated or encased in clay. No "free" silica minerals could be observed in SEM images of either granular or powder products or in dust samples collected for MSHA crystalline silica analysis. Silica minerals, such as quartz, are identifiable by SEM and EDS analysis only after removing the clay coatings by vigorous washing. After washing it can be observed that all crystalline quartz grains also have diagenetic overgrowths of what is probably opaline silica. The clay and opaline silica encapsulation of quartz plus the strongly hydro scopic nature of montmorillonite are believed to be responsible for there not being a single confirmed case of silicosis among workers in the subject plants after more than 65 years of production.

Jan 1, 1996

By Ivan V. Klumpar

If components of a gas-liquid stream react with each other and with stationary solids, involving parallel and sequential, reversible and irreversible, and slow and instantaneous reactions, the process can be defined by a set of simultaneous differential rate equations and simulated as multistage semibatch re¬actors. Each stage is divided into finite time increments. Within each increment, even the simultaneous reactions are treated as sequential. The proposed method follows process evolution from non-steady state startup to normal operating conditions. It allows computing byproduct buildup in recycles, tracer response curves and, in case of underground processes, expansion to adjacent parts of the deposit.

Jan 1, 1979

By Günter Strappler, Max John

When tunneling through karstic terrain, diverse and complex karst structures are to be expected. By means of drilling ahead of the face using drill jumbos, these structures can be detected to such a degree that by applying proper support measures both open karst cavities and karst holes surrounded by boulders embedded in soft rock can be mastered without causing any break-outs. Support measures such as spiles ahead of excavation, sealing off cavities, back?lling with sand, etc. have to be planned schematically and adapted to the dimensions and formations of the karst structures on site. An essential requirement for a smooth excavation procedure is the availablility of all necessary tunneling equipment for excavation by drill and blast as well as for excavation of soil, with experienced tunnel engineers being in charge of any adaptions on site.

Jan 1, 2003

By C. W. Matthews

Introduction Screening is defined as a mechanical process which separates particles on the basis of their size and their acceptance or rejection by a screening surface. The key element in this method of particle sizing is obviously the screening surface, the medium that contains the apertures for the passage of the undersize material. This surface must be strong enough to support the weight of the material being screened, flexible enough to yield to the vibrating force applied to it, yet light enough to provide a reasonable ratio of open area to attain a practical through- put. To balance all of these factors is difficult enough. The problem is compounded, however, because screening media are made in a great variety of types, shapes, sizes, and materials of

Jan 1, 1985

By B. V. Driga

The paper presents the evaluation method of the thermal power potential of the salt lakes developed in collapsed salt mines in Romania. It is well-known that the hydro-chemical stratification of these lakes favors warmer internal layers. The degree of heat varies during the year, but, taking into account the large number of genetic lakes of this type, it can be used as a local utilizable power source. The authors analyze the correlations between the physico-chemical parameters of the water and the degree of heat stored as a function of the morphological parameters of the lakes, as well as the technical parameters for capitalizing on this power.

Jan 1, 2008

By B. Devulapalli

A mathematical model of the industrial hydrocyclone based on fluid dynamics is a better alternative to the currently existing empirical models. The swirling-flow velocities are determined by solving the Navier-Stokes equations with an appropriate turbulence model. The solution of the momentum-balance equations yields the flow field inside the hydrocyclone which determines the particle trajectories, and subsequently the classification curve. The essence of the model is that the physical dimensions of the hydrocyclone and the slurry characteristics can be incorporated, and the influence of these parameters reflects on the flow predictions. The predicted tangential and axial velocities in a 250-mm hydrocyclone are in good agreement with the laser-Doppler velocimetry measurements. Finally, the predicted classification curves show good agreement with experimental data measured on a KREBS Dl0B hydrocyclone.

Jan 1, 1993

By R. G. Darmody

Longwall coal mining in southern Illinois occurs beneath some of the best agricultural land in the U.S. This region is characterized by highly productive, nearly level, and somewhat poorly drained soils. Subsidence from longwall mining causes changes in surface topography which alters surface and subsurface hydrology. These changes can adversely affect agricultural land by creating wet or ponded areas that can be deleterious to crop production. While most subsided areas show little impact from subsidence, some areas experience total crop failure. Coal companies are required by law to mitigate subsidence damage to cropland. The objective of this study was to test the effectiveness of mitigation in restoring grain yields to their pre-mined levels. The research was conducted on sites selected to represent conventional mitigation techniques on the predominate soils in the area. Corn (Zea mays L.) and soybean [Glycine max.(L.) Merr] yields in 1988, 1989, 1990, and 1991 from mitigated areas were compared to yields from nearby undisturbed areas. There was no significant (a=0.05) difference in soybean yields averaged over the four years. Average corn yields, however, were significantly lower than reference areas. The impact of subsidence and mitigation is variable and site specific. Results were also related to weather. In wet years, yields in mitigated areas tended to be depressed. This research demonstrated that mitigation of subsidence damage can be successful.

Jan 1, 1986

By S. K. Kawatra

The fly ash from coal combustion often has a high unburned-carbon content. This can make it unusable as a cement admixture, which is the major fly ash utilization market. As a result, high-carbon fly ashes currently disposed of by landfilling, at sometimes considerable expense. In this paper, the use of froth flotation to remove the unburned carbon from fly ash is described. Three different fly ashes were studied, which had Loss-on-Ignition (LOI) values of 6.79, 6.90, and 11.11 %. It was found that the use of an alkanolamide/oil mixture as a froth-conditioning reagent could greatly reduce the amount of collector needed, by increasing the affinity of the collector for oxidized carbonaceous surfaces. For each of the three fly ashes, froth flotation reduced the LOI of the ash to less than 2% which is well below the ASTM specification of no &apos; more than 6.0% LOI for Class F fly ash. Increasing carbon content of the ash tended to increase the quantities of reagents needed in flotation.

Jan 1, 1996

By M. A. D. Azevedo

The effect of pulping reagents on the flotation de-inking of laser printed wastepaper was investigated with regard to the removal efficiency of toner and mineral filler particles for different pH values. These results show that caustic pulping causes the toner to be released from the fibers at larger particles sizes. On the other hand, acid pulping not only causes the toner to be released at smaller particles sizes but also increases the concurrent flotation removal of mineral filler particles. It was experimentally observed that the froth generation and stability during flotation were improved for acidic pH values.

Jan 1, 1997

By J. C. Cawley

Improvements in today&apos;s maintenance practices are mandatory as more complex and productive machines evolve in the mining industry. By keeping machine reliability high, through improved maintenance procedures, overall mining costs can be reduced. The Bureau of Mines is investigating diagnostic maintenance systems for underground mining machinery. A hydraulic expert diagnostic system and an electric motor predictive diagnostic system have been designed and installed on a Joy 16CM continuous miner. An electrical diagnostic system has been designed and installed on a Joy 14CM continuous miner. Each system is functionally described and the relative merits of expert diagnostic systems versus algorithmic diagnostic systems are discussed.

Jan 1, 1991

By E. Craig Simmons

Uranium is an element incompatible with respect to the major rock-forming minerals crystallizing from granitic magma, entering in- stead trace minerals such as zircon. The relationship between the saturation limit (SL) for such a mineral and the bulk distribution coefficient (Do) for U is central to understanding the distribution of U and its availability to late- stage fluids which can form ore deposits directly, or labile U which can be remobilized later. Low SL values imply early crystallization of zircon, but in very small proportions, minimizing Do and maximizing the degree of enrichment of U in late-stage fluids. Thus, granitic rocks with low Zr contents (due to a low saturation limit for zircon) are most likely to evolve U- enriched differentiates; this will be reflected in a high U content of the zircons (but not necessarily high U abundances in whole-rocks). Thus, the ratio of the U content of zircon to the Zr content of the corresponding whole-rock is potentially a very useful parameter in identifying granitic rocks which are most likely to have U-enriched solutions associated with them. The granitic rocks associated with the U deposits of the Midnite Mine area, Washington, have geochemical characteristics which fit very well the model presented here. The rocks are very low in Zr (100 ppm) and contain zircons with extremely high U contents (3,000-4,000 ppm).

Jan 1, 1981

By L. M. Nuelle

Rare earth element (REE)-and gold-bearing breccia pipes are a potentially significant economic target in the Pea Ridge iron ore mine, Washington County, Missouri. The Pea Ridge deposit is one of eight known volcanic-hosted iron ore deposits in the Middle Proterozoic St. Francois terrane, which are similar to the Olympic Dam-type deposits of Australia. The iron orebody is steeply dipping, tabular-shaped, and cuts across the host rhyolite. The footwall of the deposit is zoned from the massive apatite-bearing magnetite core outward to heterolithic breccia, pseudobreccia, specular hematite zone, to an extensive silicified zone. The hanging wall is zoned from the massive magnetite core outward to a heterolithic breccia, pseudobreccia, and an amphibole skarn zone. The REE-rich breccia pipes cut through the various lithologies along the footwall at or near contacts. They are typically 60 m long, 15 m wide, and extend at least 120 m vertically. The pipes are comprised of fragments of rhyolite host rock, massive magnetite zone, specular hematite zone, and silicified zone rocks supported in a matrix of rock flour, barite, feldspar, monazite, apatite, chlorite, xenotime, and, locally, gold. Total REE oxide content of samples of the ground mass material, which are not diluted with lithic fragments, average about 20 weight percent. Grades from working faces in the mine are lower and average about 12 weight percent. Gold distribution is erratic, but concentrations are as high as 371 parts per million.

Jan 1, 1991

By F. P. Jung

This presentation will be a general overview of the Cerrejon Coal Project being developed jointly by Carbocol, an entity of the Colombian government, and Intercor, an Exxon affiliate. The word "Cerrajon", by the way, is simply Spanish for a small hill. There is a distinctive hill near the mine site, and it&apos;s the only landmark of any significance. It&apos;s shown in Figure 1. So the locals call this area "El Cerrejon", "the little hill." Let me start with some of the highlights of the project, summarized in Figure 2, and then go into more detail later. A four-year feasibility study covered the geology, quality, engineering, construction operation and marketing of coal from this region. This study led Exxon to declare the project as commercial in July of 1980. Then in September of 1980 the president of Colombia gave the government&apos;s okay to proceed.

Jan 1, 1982

By Wade W. Bristol

The Jerritt Canyon Joint Venture project is located about 80 km (50 miles) north of Elko, NV. It produces approximately 9.3 t/a (300,000 oz/year) of gold. The joint venture is 70% owned by Independence Mining and 30% by Meridian Gold. Independence Mining is the operator. The Jerritt Canyon Joint Venture started operations in 1980 by mining a series of open-pit mines. The discovery of deeper ores during early 1990s made it neccessary for the operation to mine a large portion of its annual production by underground mining methods. Underground production started in 1993 at the West Generator Mine. This was followed by the Murray Mine in late 1994. Two additional underground projects are being developed. Underground mining at Jerritt Canyon is scheduled to produce about 3.9 t (128,000 oz) in 1997.

Jan 1, 1997