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By Choon K. Quan

Subsidence is a surface manifestation of the underground development and exploitation of minerals, and its impact on the environment is becoming of increased concern, particularly in the face of an accelerating demand for energy and minerals. In the United States, the state-of-the-art in subsidence prediction, control, and prevention and in subsidence-related damage abatement has not progressed to the level achieved in other countries. To bridge this gap, the Bureau of Mines, through its Mining Environmental Research program, is pursuing a comprehensive subsidence investigation, specifically designed to address major problems on the local, regional, and national level.

Jan 1, 1979

By C. L. Peng, F. F. Min, S. X. Song

"Using a parameter representing the degree of hydration of particles in a liquid called hydration index I, which we derived based on Einstein’s viscosity equation, we evaluated the degree of hydration of fine montmorillonite particles in different aqueous solutions by measuring the viscosities of the montmorillonite dispersions and plotting relative viscosity against volume fraction of dry montmorillonite particles in the dispersions. We investigated the effects on the hydration of montmorillonite in aqueous solutions of (1) the type and (2) the concentration of electrolytes in the solutions and (3) pH. For the same concentration of electrolytes, the hydration index I of montmorillonite was found to increase in the order of Na+ > K+ for monovalent cations and Mg2+ > Ca2+ for divalent cations, and to decrease with increasing valence of cations in the order of Na+ > Ca2+ > Al3+. For both Na+ and Ca2+, the hydration index I first increased with increasing concentration of electrolytes and then decreased after a certain concentration. The hydration index I increased with increasing pH. IntroductionClay minerals have the distinctive ability to adsorb water molecules and hydrated cations in aqueous solutions, resulting in hydration on their outer surfaces and in their interlayer spaces. Many investigators (Jurinak, 1963; Anderson and Tice, 1971; Costanzo et al., 1982; Israelachvili, 1992) had found evidence of ice-like structures of water on clay minerals.This phenomenon of hydration plays an important role in the dispersion and sedimentation of clay minerals in aqueous solutions. To understand clay hydration, numerous experimental and simulation studies have been carried out since 1933, including the recent ones of Hawkins and Egelstaff (1980), Skipper et al. (1995), Karaborni et al. (1996), Salles et al. (2013) and Morrow et al. (2013). Among the factors that can influence a clay mineral’s hydration characteristics are chemical composition, type and degree of isomorphous replacement in its structure, and number and nature of associated exchangeable cations."

Jan 1, 2015

By Steve Kral

Despite low commodity prices and mining industry cutbacks throughout the world, Peru remains one of the industry’s bright spots. The country’s remarkable economic turnaround during the 1990s remains a model for other developing nations to follow. And the Peruvian government has not forgotten the industry that was instrumental in that turnaround. True, the country has not been spared the effects of the mining industry’s retrenchment that has occurred in other parts of the world. However, foreign mining companies remain committed to doing business in Peru. And the government remains committed to attracting foreign investment and maintaining a strong mining industry. This commitment was evident in September 1999during the 24th Convention of the Institutos de Ingenieros de Minas del Peru in Arequipa, Peru. More than 3,000 mining industry professionals from around the world attended the convention. And Extemin, the accompanying exhibit, featured more than 450 companies, many from the United States, Canada, Australia, South Africa and other countries.

Jan 1, 2000

By M. Xing, S. Usman, K. Awuah-Offei

"While mines generally focus on achieving operational efficiency, creating shared value for all stakeholders is also a management goal. This includes taking a holistic view of their supply chains and increasing local participation. This paper examines the role of supply chain management in mine management; in particular the effect of a strong local supply chain on regional economic impacts. Using input-output analysis, the impact of a local supply chain on a mining sector’s regional economic impact is examined by increasing local sourcing (increasing local purchase percentage -- LPP) for 10 key commodities. An approach, based on multipliers and excess local capacity is used to identify key commodities. The impacts examined are sales, employment, labor income, and value added. The work is illustrated with stone mining and quarrying in Missouri. Ten percent increases in LPP of the key commodities, in this example, result in $4.1 million additional impact on the Missouri economy. This work can provide insight on how to better create shared value for all stakeholders. INTRODUCTION Little research has been published on improving mine supply chain management (SCM) to enhance regional economic impacts. Although some extensive academic research has explored the importance of an industries’ supply chain, not much is known about how a locally-based supply chain increases shared value in the resource sector. Across industries, traditional SCM is getting more and more complex. This is true of the mining sector as well. However, this increased sophistication is not directed towards increasing shared value for all stakeholders, particularly, the local communities. Further research is required to develop new SCM strategies that enhance local participation. One major point of difference between this work and traditional supply chain management is the inclusion of stakeholders’ shared value as a goal in SCM. Creating shared value has become a business goal in recent years (Porter and Kramer, 2011). The authors use input-output analysis (Leeuw, 2012) to evaluate the regional economic impacts of supply chain decisions, which is not part of traditional SCM. Although input-output analysis has been applied to SCM for decades, most of the research uses input-output analysis as a tool to advance an industries’ own operational efficiency (Accenture, 2014)."

Jan 1, 2015

By R. C. Berry

The Environmental Impact Statement (EIS) has become a routine requirement for mining operations on federal lands. A similar document is being required in developing countries. Baseline studies are needed prior to writing an EIS and these studies involve surface water, groundwater, air quality, and wildlife/ native plant evaluations. The required baseline hydrology and geochemical studies are often the most expensive and lengthy evaluations. This paper summarizes the hydrology and geochemical baseline studies required for .An EIS and presents suggested methods to expedite these studies and to shorten the time and the cost to complete the studies and the EIS.

Jan 1, 1999

By C. A. Hollingsworth

The Deep Leg Flotation Cell was developed to solve a problem which confronted the Smith-Douglass Company on moving from one mining area to another. Poor recovery and, to some extent, inferior concentrate grade were encountered in the silica flota¬tion circuit. This was believed due to the softness of the phosphate which caused it to form slime. In view of the urgency of the matter, the problem was attacked from two angles. The first involved the development of a flotation cell which would not create slime and the second, a new or improved reagent for floating silica from phosphate rock which would be less sensitive to slime than reagents currently in use.

Jan 1, 1964

By Yuemin Zhao, Daniel Tao, Rick Honaker, Maoming Fan

"Froth flotation is the most widely used method of separating fine coal, especially coal with coking properties. However, froth flotation is not efficient for treating ultrafine coal and coarse coal particles. Our previous fundamental test results demonstrated that cavitation-generated nanobubbles around 700 nm in diameter can significantly improve coal and phosphate flotation performance over a wide particle size range. In this study, the effect of nanobubbles on the flotation performance of different particle size fractions of coal was investigated using a bank of 10-L flotation cells, a specially designed 50-mm inside diameter column and a 152-mm inside diameter column. It was found that nanobubbles that were either directly formed on or subsequently attached to the surface of coal particles during the froth flotation process improved flotation efficiency. The use of nanobubbles in a bank of mechanical cells flotation and column flotation significantly increased the flotation recovery at a given product grade. Nanobubbles increased the flotation rate constants of different coal particle sizes. The presence of nanobubbles in flotation slurry could extend the lower and the upper particle size limits for effective coal flotation.IntroductionFor minus 0.6 mm fine coal or minus 0.15 mm ultrafine coal particles, froth flotation is known to be the most efficient and the most cost-effective separation technique. However, flotation efficiency decreases sharply with ultrafine and relatively coarse coal particles. Studies have shown that the low flotation efficiency of ultrafine particles is mainly due to the low probability of bubble-particle collision (Yoon et al., 1989; Ralston and Dukhin, 1999). Enhanced flotation of fine and ultrafine coal can be achieved by increasing collision and attachment probabilities.The top size of particles that can be recovered by flotation depends on the combination of mineral properties and flotation devices. Turbulence in flotation devices is an important factor that affects the stability of bubble-particle aggregates. Even in the flotation of fine particles, bubble-particle detachment can significantly influence the kinetics of flotation taking place in mechanical cells, which provide intensive turbulent agitation (Deglon et al., 1999). Coarse particle flotation is more difficult, because increased agitation is required to maintain particles in suspension and coarse particles are more likely to detach under turbulent conditions (Mankosa and Kohmuench, 2002; Soto and Barbery, 1991). More efficient attachment of particles and improved flotation rate has been observed when tiny bubbles coexist with conventional-sized flotation bubbles (Attalla et al., 2000; Tao et al., 2010; Fan et al., 2010a, b, c, d; Fan et al., 2012)."

Jan 1, 2015

By Burke Trafton

An earlier paper1 introduced a rapid solution for mine ventilation network problems, employing the digital computer. In this paper, refinements and additions to the computer program which expand its scope of application and a solution to a ventilation network having a coal-mine configuration are presented. Specifically, the revised program--written in FORTRAN for the IBM 7074 computer in Penn State's Computation Center--is applicable to any mine ventilation network employing natural splitting and having its fan located externally. It accomplishes the following; 1. Distributes an assumed total quantity of air flow among all air- ways of the network, performing iterations until an acceptable level of error is attained and the flow in each airway is known. 2, Computes the pressure drop (head loss) in all airways and the overall network and mine head losses. 3. Determines the operating point for the mine and a given fan, adjusting all air flows and head losses to the actual values.

Jan 1, 1964

By Winn B. Frank

Events of the mid-1970's have materially affected US coal production and transportation by railroad. Coal, as a replacement or substitute for petroleum fuels, has been hauled in significantly increased tonnages. Concurrent with the new demand, the railroad regulatory environment has undergone major changes, especially in "deregulation" activity. Those two events have produced considerable Litigation regarding coal rates. This paper discusses the factors involved with railroad rates and topics such as revenue adequacy, Ramsey Pricing, stand-alone cost, and differential pricing. In addition, an update on the western railroad merger situation and the implications for coal transportation are presented. The paper concludes with an evaluation of the current regulatory climate and future prospects.

Jan 1, 1983

By Gary B. Glass

Seventeen percent of US coal production now comes from the 19 surface coal mines in the Powder River Basin of northeastern Wyoming. The Powder River Coalfield, which coincides with this topographic and structural basin, is unique to the conterminous US, in that it contains an estimated 934.4 Gt (1.03 trillion st) of in-place coal resources. At least 13.2 Gt (14.6 billion st) is a compliant, strippable reserve base. In 1993, an estimated 162 Mt (179 million st), or 98% of the coal mined in this Wyoming coalfield, came from the thick - average 30.5 m (100 ft) - subbituminous, Wyodak coalbed, or from the Anderson and Canyon coals in the one mine where the Wyodak is split into two separate coalbeds. The other 2.7 Mt (3 million st) of coal mined in the Powder River Basin in 1993 came from the School, Badger, Monarch and Deitz No. 3 coalbeds. In this "world class" coalfield, there are at least 13 other persistent, 3 to 15 m (10 to 50 ft) thick, coalbeds as well as the Big George and Lake De Smet coalbeds, which are each 61 m (200 ft) or more thick in places. None of these latter 13 coals are mined at this time.

Jan 1, 1994

By N. S. Tanious

This work was completed prior to the author's appointment with the Nuclear Regulatory Commission (NRC). Therefore the views and conclusions contained in this paper are those of the author and should not be interpreted as necessarily representing the official policies or recommendations of the NRC. Reference to specific brands, instruments, or trade names is made to facilitate understanding and does not imply endorsement by the author or the NRC.

Jan 1, 1987

By L. A. Bellows

The "Athabasca oil sands" of the McMurray formation in northeastern Alberta cover an area of about 21,000 square miles and contain the world's largest reserve of oil. Fort McMurray, a small town in the heart of the oil sands area, is about 235 air miles north- east of Edmonton. A railway serves the town but no year-round roads connect the town with the rest of Alberta. (Figure 1). The McMurray formation is of early Cretaceous age, deposited unconformably on a limestone surface of Devonian age. The sediments appear to have originated from the Canadian Shield to the east and were deposited in bays and deltas of large fresh water lakes. The lakes were later replaced by marine seas in which t the overlying Clearwater shale was deposited. (Figure 2).

Jan 1, 1963

Thermal pretreatment can significantly improve industrial comminution operations by reducing energy requirements and increasing mineral liberation. The effect of pretreatment using conventional and dielectric heating followed by quenching on the fracture properties of a number single and multiphase brittle materials has been investigated. The reduction in the impact fracture energies and particle strengths with and without pretreatment has been measured in precise single-particle experiments using the Ultrafast Load Cell. Variations in the fragmentation pattern caused by different pretreatments were assessed by measurements of the progeny size distributions. The differences in the effect of thermal treatment on single and multiphase materials are discussed based on the experimental results.

Jan 1, 1995

By Theodore J. Barrett

[One of the earliest records of pillar removal can be found in the 16th Chapter of Judges in the Old Testament. Here we read where the mighty Sampson removed the pillars from beneath the prison house causing the collapse of the structure resulting in his own death along with the deaths of the 3,000 Philistine occupants. Our problems at the Mi Vida Mine differ somewhat from those of Sampson of old, in that it is our aim first to remove the pillars and get out from under the back before the "house falls in" and, secondly, to remove the pillars without the lose of a single life or without even a single casualty. As of January 15, 1959, the Mi Vida accident record stood at 772 days without a lost-time accident]

Jan 1, 1959

By Ben Sosewitz

The subject of rapid excavation tunneling is one that is extremely important to the people in the Metropolitan area of Chicago. My personal observation is that it is also extremely important to the urban communities around the U.S., to many local and state governments, and to the public officials who are deeply concerned about state affairs and taxes. The Metropolitan Chicago area is in fact, (as are 40 other major urban areas in the U.S.) confronted at the present time with a very serious combined sewer overflow, drainage and pollution problem which accounts for an estimated 40% of the pollutional load on its waterway system. In response to this the District has to date spent some seven millions of dollars in an attempt to find the most economical solution available for the elimination of this problem. This study included extensive investigations of the geological strata, the quantity and quality of storm runoff to be dealt with, and the various methods of storage and treatment available. It has considered solving the overflow problem by a concept involving a series of tunnels, rock tunnels, shafts and storage areas which will collect, retain and subsequently treat that portion of the combined sewer overflow which can be handled in the most cost-effective and economical way, consistent with following the federal and state standards - with which we at the present time agree in principle.

Jan 1, 1997

By B. J. Arnold, N. Terblanche

The features of the ‘Turbo’ froth flotation column will be discussed, including the double aeration system that improves flotation yield while not sacrificing grade, the internal launder system, and the unique feed/tailings sump that evens out flow to the flotation column preventing upset conditions. Results from various test programs and installations will be presented.

Jan 1, 2001

By Allegra Yeley, Ted Klemetti, Gamal Rashed, Tim Miller, Nicole Evanek

In 2015, the Subtropolis Mine in Petersburg, OH, experienced a massive ground collapse that continues to grow over time. Horizontal stress effects have affected the roof at this operation in the past and may have played a large role in this collapse. Horizontal stress can impact the roof and floor stability and endanger the health and safety of underground stone miners. Mines experiencing damaging effects from horizontal stress typically find that the principal stress direction is the same throughout the mine and the region. At the Subtropolis Mine the principal horizontal stress direction appears to change as conditions change and differs from the regional horizontal stress, particularly near the collapse or other roof fall areas. The growth over time of this collapse and other roof falls have been captured and analyzed using geologic mapping, 3D LiDAR scanning, numerical modeling and geographic information systems like ArcGIS. Utilizing these tools to better understand sitespecific conditions can be critical to reducing the potential of massive ground collapses in the underground limestone industry.

Feb 1, 2024

By Frank J. Foster

This Paper will deal with Bucketwheel Suction Dredging and its particular relationship to mining applications. There will be comparisons with other methods of suction dredging and descriptions of two recent bucketwheel installations in the mining area. The Directory of World Dredging Fleets published in the `larch 1984 edition of World Dredging magazine shows that there are about 1.000 conventional Cutterhead Dredges listed throughout the world with 289 in the United States. There are 242 Bucketline Dredges listed throughout the world of which only 6 are in the United States. These figures are not completely accurate because several units are known to the author that are not on the list and, of course, there may be others.

Jan 1, 1984

Face and pillar bursts, bumps and bounces are violent failures that occur in underground coal mines in response to a complicated interplay of face and pillar geometry, seam depth, coal properties and interactions between roof, seam and floor strata. Additional complications arise from the presence of gas, mainly methane, and associated pressure and flow that vary with time and are further influenced by the rate of face advance. Where gas plays a dominant role, the term outburst is often used; where stress concentration is primary, terms such as burst, bump or bounce may be used. Hargraves [1983] presents an often cited review of outburst phenomena with emphasis on Australian conditions. Beamish and Crosdale [1998] indicate outbursts have occurred for over a hundred years and present tabulations of outburst numbers in major coal basins throughout the world. A central consideration is the rate of depressurization that occurs in the course of mining. Outbursts are not limited to coal seams and adjacent strata; they also occur in salt and potash mines [Molinda et al 1988]. Stress concentration and gas pressure act in consort, so the combined action is important to understanding the mechanics of bursts or outbursts and to the development of measures to reduce the associated hazard. Gas flow is a complicated phenomenon associated with diffusion of gas from micro-pores and the flow of gas along cleats. Laboratory measurements indicate both are dependent on stress and pressure [Harpalani and Ouyang 1998]. Moreover, gas permeability in porous media is often many times water permeability [Klinkenberg 1941]. However, there is also evidence that gas and water permeability are similar at elevated stress and follow Darcy?s law [Dabous et al]. Gas flow is also of importance to mine ventilation. Price et al [1973] in cooperation with personnel of the former U.S. Bureau of Mines developed finite difference models to estimate methane emission in mines in the Pocahontas No. 3 and Pittsburg seams using a premining pressure of 4.69 MPa (680 psi) and Darcy's law implying laminar flow. However, the effects of stress were not taken into account. In this regard, mine measurements of permeability are usually based on Darcy?s law [Peide 1990]. Early models of gas flow with stress effects were one-dimensional in space and time (x,t) and were developed with the goal of estimating the gas pressure profile from the face into the seam as time passed [Schlanger and Paterson 1987, Zou and Yu, 1999]. A zone of high permeability adjacent to the mining face was recognized in these early models. Later models based on the popular finite element method allowed two spatial dimensions (x,y) and variation in time (t) and for coal seam heterogeneity [Tang et al, 2002]. Zhu et al [2007] formulated a set of nonlinear equations involving a complicated stress-pressure-permeability relationship for application to coal seam gas flow and concluded the coupling was important but failure of coal should also be considered. Wold et al [2008] used a hybrid finite difference - finite element model interleaved with a reservoir simulation model to study outbursts based on extensive mine and laboratory measurements. An important feature of the modeling was the use of spatially variable material properties and Monte Carlo simulation to obtain quantitative estimates of outburst conditions and probabilities. Connell [2009] used the same reservoir simulation model as Wold but used the popular finite difference code FLAC3D for hydro-mechanical responses to evaluate two permeability relationships, one depending on porosity and the other on stress, and concluded that permeability changes with gas production were more complex than computed by either permeability model. Gadde [2010] in an integrated laboratory and field study of coal pillar strength explored the effect of spatial variability and concluded that design based on average strength was acceptable in some circumstances, although gas pressure was not an issue. Liu et al [2011] also applied a FLAC code to analyze two-dimensional gas flow and deformation of layered but homogeneous strata in a Chinese coal mine using a strain-softening model and concluded that damage and gas pressure were important to strata safety relative to the case without gas.

Feb 27, 2013

By Michael J. Rinker, P. A. Tibble, M. Wiseman, R. V. Nicholson

Tailings, from an active copper-zinc operation, containing about 10% sulphur were investigated to assess the onset of acid production and potential lime requirements for treatment of drainage. Oxygen consumption rates were measured over two years to verify spatial and seasonal variations in sulphide oxidation rates. Shallow cores were collected to assess the quality of tailings porewater and to characterize solids that had been subjected to oxidation and depletion of neutralization potential (NP) for several years. Oxygen consumption data were used to quantify rates of NP depletion and onset of acid drainage from the near- surface tailings. Based on measured oxygen consumption rates and identification of NP remaining in the tailings, future lime use in the treatment plant was expected to rise significantly without mitigation. Geochemical modeling calculations were calibrated with observed oxygen consumption rates and the model results agreed well with actual lime use in the waste water treatment plant during operations. The modeling also demonstrated the benefits of lower lime demands and treatment costs after closure as a result of construction a soil cover on the acid generating tailings.

Jan 1, 2000