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By Allison

During the 1980’s, laboratories opened throughout the United States to serve the analysis needs of a rapidly growing asbestos abatement industry. The samples analyzed were either collected during the abatement of known asbestos-containing materials or were suspect asbestos-containing construction materials. Many asbestos analysts received minimal training and used analytical protocols that were industry specific. False positives (reporting a sample as containing asbestos when none is present) went unnoticed or had minor repercussions. The mindset of the industry was to err on the conservative side – it would be better to identify a non-asbestos fiber as asbestos than visa versa. With growing public awareness of the health hazards of asbestos, other materials began to be tested for asbestos content. Rock and ores began to be tested for naturally occurring asbestos by these laboratories using the same protocols or an in-house protocol. Analysts were given no additional training and accreditation, in most cases, it was not required. With no consistency in sample collection, testing protocol or expertise in analysis, significant discrepancies in final results can be expected. If we further complicate this scenario with misidentification of naturally occurring look-a-likes for asbestos, expensive false positives are likely. To avoid the repercussions of misidentification of naturally occurring chrysotile asbestos from look-a-like fibers in rock and ores, correct sampling and analysis protocols with more stringent scientific diagnostic criteria are needed.

Jan 1, 2005

By M. Okido, W. Wei, L. Chai

The kinetics on the growth of Thiobacillus ferrooxidans was studied by use of series piezoelectric quartz crystal ( SPQC ). Arsenic ioninhibits the growth of Thiobacillus ferrooxidans, which is consistent with the previous results by other measuring method. This further demonstrates that the SPQC can monitor the chemical activity of the growth of Thiobacillus ferrooxidans. Cupric ion accelerates the growth of Thiobacillus ferrooxidans. The mechanism was discussed, it was considered that copper promotes the protein enzyme of Thiobacillus ferrooxidans, rustic yanin, to form over the range of cupric ion concentration studied. There action order of cupric ion in accelerating the bacterial growth is 0.067. The growth of Thiobacillus ferrooxidans is dependent on temperature, the apparent reaction activation energy decreases from25.56 kJ / mol to 18.32 kJ / mol because of the addition of 10 mg / L Cu(II) to the bacterial growth solution of pH 2.0 at initial inoculum of 10%.

Jan 1, 2000

By Steve Kral

U.S. mines are among the most efficient, productive and safest in the world. Much of that efficiency is due to the high-technology equipment and processes available to the industry. The U.S. mining industry can produce more material now with fewer people than it could a few decades ago. And that material can be produced more safely. However, the workforce is growing older and fewer young people are filling the holes created by retirements. Even though mining is one of the highest paid occupations in the United States, young people believe they can find jobs that pay almost as well without the risks and the often remote locations associated with mines.

Jan 1, 2002

By Nikhil Dhawan, Ashwini Kumar, Yogendra Pratap, Himanshu Tanvar

India does not possess any soluble potash reserves and depends completely on imports. In this study, an attempt has been made to recover potash (K) values from the mica sample employing thermal and mechanical routes followed by leaching. Direct leaching of mica in different lixiviants is found to be ineffective with very low K-dissolution (1–5%). Heat treatment with different fluxes, such as NaCl, NaOH, and CaCl2, is carried out and almost 85% K-values are recovered. Mechanical activation of mica and with different calcium additives is carried out to recover potash values. K is recovered in leach solution in the form of soluble salts, such as K2CO3, K2SO4, and KOH, and leach residue consists mainly of calcium-alumino-silicates. Using mechanical activation with flux, it is possible to recover >95% K-values from mica sample. Mechanical activation with calcium-based flux is found sustainable in the recovery of K-values from mica.

By Leslie F. Ruppert

The US Geological Survey (USGS) is currently conducting a coal resource assessment of the coalbeds and zones that are projected to provide the bulk of the nation’s resources for the next few decades. The Pittsburgh and Upper Freeport coals are the first two beds in the northern and central Appalachian basin region to undergo fully digital coal assessments. The bed-specific assessments are being carried out in partnership with the state geologic surveys of West Virginia, Ohio, Pennsylvania and Maryland. Comprehensive stratigraphic and geochemical databases have been developed for both of the beds. The extent of the bed with mined areas, structure contour, isopach, and overburden thickness maps for the Pittsburgh coal bed have been released as USGS open-file reports.

Jan 1, 1999

By Y. Q. Zhang, Y. Luo, S. S. Peng, C. T. Holland

Barrier pillars in underground coal mines could eventually be subjected to a hydraulic pressure head due to the build-up of mine water in the old workings. The pressure head could not only act as a force to destabilize the pillar but also cause seepage flow through the pillar and its surrounding strata. Excessive seepage flow could induce piping failure that in turn could accelerate the mechanical failure process of the barrier pillars. In this paper, finite element simulation approach has been employed in the evaluation of the barrier pillars. Both the stress distribution and the seepage flow pattern in and around a barrier pillar have been simulated numerically. The effects of ground stress on rock permeability to water seepage has been taken into consideration in these simulations.

Jan 1, 2001

By Bo Forsman

METAFORA is a simulation model for determination and evaluation of strategies for operating loader/truck systems in mining. A specific version of METAFORA was used to evaluate the haulage system at Solider Mineral's Aitik mine in northern Sweden, one of the largest open pit mines in Europe with a production of about 11.5 Mtpy (about 34000 tpd) of copper are. A production level of 34065 tpd was estimated by simulation runs with METAFORA. Using METAFORA's dispatch rules (Fixed Dispatch, Maximize Trucks, and Maximize Loaders), the truck/shovel system in the Aitik mine was simulated for evaluating alternative dispatch control strategies. The Maximize Trucks rule gave about the same total production (ore + waste) as the Fixed Dispatch rule but a 9% higher ore production. The Maximize Loaders rule gave the lowest production. The marginal truck capacity decreases with increasing number of trucks serving the same loader due to increasing waiting times. In Aitik mine the low crusher capacity results in long dumping times. If the dumping time at the crusher could be halved, the ore production would increase by 14%. The paper indicates that the use of software like METAFORA can result in a substantial reduction of time, effort and cost in shovel/truck system design and evaluation.

Jan 1, 1992

By Wen Tao Liu, Tong Tian, Fu Sheng Niu, Xiu Man Liang

In order to address the difficulty of accurate segmentation of froth images of different sizes, a method of froth image segmentation based on highlight correction and parameter adaptation is proposed. First, a machine vision system on a single-cell flotation machine is built to collect froth images. Homomorphic filtering is used to improve the uneven brightness and shadow of the images. Fuzzy c-means (FCM) clustering is then utilized to classify similar highlights that belong to the same froth. After Otsu threshold segmentation, a parameter-adaptive morphological operation is used to extract the marker points and edge bands and correct the froth edges in the original image. Finally, the modified image is filtered by morphological reconstruction, and the highlight mark is used as the local minimum point for watershed segmentation. Three sizes of froth images are segmented in comparative experiments. The results show that the proposed method is suitable for the segmentation of froth images of different sizes. The position of the extracted segmentation line is close to reality, with average over-segmentation and under-segmentation rates for froth images of 2.6% and 6.8%, respectively. The froth image segmentation performance is stronger than that of the other methods examined.

By W. Rogers

Blast-induced rock mass displacement can have a significant impact on ore loss & dilution. The mischaracterisation of the grade boundaries both prior to, as well as a result of blasting can lead to significant financial losses on account of ore loss and dilution. Ore dilution occurs when waste material is miscategorised as ore and sent for processing or stockpiling, diluting the run of mine head grade and recovery. Ore loss takes place when valuable mineral is miscategorised as waste and sent to the waste dumps, thus never being processed and recovered. Extensive research has been conducted at the University of Queensland over the last fifteen years to understand the impact of blast movement on ore loss and dilution. Recent outcomes of this research have developed innovative tools and techniques to measure and model blast movement. These techniques have been implemented at Ahafo gold mine in Ghana to understand blast movement dynamics and to implement solutions to reduce blast-induced ore loss and dilution. These solutions are validated through controlled trials and have been incorporated into site standard operating procedures to sustain the benefits.

Jan 1, 2012

By L. F. Ruppert, W. D. Watson, S. J. Tewalt, L. J. Bragg

The U.S. Geological Survey recently completed a digital coal resource assessment model of the Upper Pennsylvanian Pittsburgh coal bed which indicates that of the original 34 billion short tons [31 billion tonnes] of coal, 16 billion short tons [14 billion tonnes] remain after subtracting mined-out coal. When technical, environmental, and social restrictions are applied to the remaining Pittsburgh coal model, only12 billion short tons [11 billion tonnes] are available for mining. Our assessment models estimate that up to 0.61 billion short tons [0.55 billion tonnes], 2.7billion short tons [2.4 billion tonnes], and 8.5 billion short tons [7.7 billion tonnes] could be available for surface mining, continuous mining, and longwall mining, respectively. This analysis is an example of a second-generation regional coal availability study designed to model recoverability characteristics for all the major coal beds in the U.S.

Jan 1, 2000

By A. T. Iannacchione

From 1990 to 1996, 16 states reported 92 injuries from falls of roof, rib or face in the more than 90 underground stone mines in the United States (Fig.1). Missouri, Pennsylvania and Kentucky accounted for 48% of the total number of injuries (Fig. 2). Of this total, 11 miners were killed. Of the 11 fatalities, 10, or 91%, were associated with unrecognized loose or failed rock within the roof beam. Additionally, unrecognized roof beam failures resulted in a majority of the falls of ground injuries occurring in underground US stone mines from1990 to 1996. This number is not large in magnitude. But a workforce of fewer than 2,000 miners makes for a high fatal-accident rate. The severity of the typical fall-of-ground injury is, in general, very high. About three-fifths of all roof, face and rib fall injuries were designated by the US Mine Safety and Health Administration (MSHA) as some kind of lost time accident. MSHA assigns each accident a severity value from one to six. A one represents a fatality, a two, a permanent disability and three, a lost time accident (Fig. 3).

Jan 1, 2000

By James A. Pendleton

In response to Public Law 95-87 (SMCRA), Colorado promulgated regulations governing the mining of Coal. These regulations require the prediction, monitoring and mitigation of "material damage" caused by subsidence. All permitted underground coal mines within Colorado have approved subsidence programs. Preliminary monitoring results indicate the subsidence mechanical predictions have been sufficiently accurate to preclude material subsidence damage. The State of Colorado has developed a practical approach to regulating subsidence, which stresses monitoring verification of predicted subsidence phenomena. However, shortcomings exist in our ability to precisely predict the secondary consequences of subsidence, including effects to structures, the hydrologic balance and the environment. Lack of accuracy in predicting these secondary consequences results in uncertainty, necessitating conservatism in permitting. To avoid increasingly stringent permit restrictions, future research should emphasize the secondary consequences of subsidence.

Jan 1, 1986

By O. Noirot, H. C. Owens, P. D. Rao, D. E. Walsh, J. R. Mokka

Over a period of seven years (1989-1996) the Mineral Industry Research Laboratory (MIRL) University of Alaska Fairbanks, has investigated the effects of temperature, residence time, and particle size on the degree of low-rank coal (LRC) upgrading for a non-evaporative, hydrothermal drying process, also known as hot water drying (HWD). Three Alaskan LRCs were used in this study: Usibelli coal (Seam No. 4) from the Nenana Coal Field, Little Tonzona coal from near McGrath, and Beluga coal from the Beluga-Yentna field on the west side of Cook Inlet. Replicated, factorial tests were conducted. Experimental results indicate that most of the low-rank coal upgrading via HWD occurs rapidly within the first 10-20 minutes of residence time. Thereafter, the upgrading process slows down and over 100 minutes of additional residence time are required to produce similar percentage increases in coal properties to those achieved in the first 10- 20 minutes. The properties of the hot water dried products were very sensitive to process temperature. Calorific value, carbon and oxygen contents, equilibrium moisture levels and Hardgrove gindabilities all appear to change linearly with temperature within the 275°C to 325°C range.

Feb 24, 1997

By K. Severin, B. Flanigan, P. Marion

“Plutonic-related” gold deposits in Interior and SW Alaska (Tintina Gold Belt) vary significantly in size, grade, vein/deposit morphology, depth of emplacement, distance from causative pluton and metal association. Metal associations such as Au-Bi and Au-As-(Sb-Hg) are a good empirical indicator of depth of emplacement and distance from causative pluton and have been used successfully in exploration. Results from a variety of analytical techniques also suggest a phenomenological cause for these metal associations, e.g. gold and bismuth have linked metallogenesis at high temperatures and thus are best correlated at deposits that are deep and/or close to causative intrusions.

Jan 1, 2000

By Dermot Winters

The Surface Mining Control and Reclamation Act (SMCRA, or the Act) was enacted on August 3, 1977. The Act was written, in part, to put an end to uneven environmental standards and to establish minimum national standards. Certainly, one of the motivating factors for passage of the Act was the success of the Federal Coal Mining Health and Safety Act of 1969 in reducing deaths and injuries in the coal industry nationwide. Section 516 (b) (1) of the Act requires *that subsidence be prevented from causing material damage to the extent technologically and economically feasible except in those instances where the mining technology requires planned subsidence in a predictable and controlled manner. Section 516 (c) of the Act authorizes the regulatory authority to suspend underground mining if there is imminent danger to inhabitants of urbanized areas, cities, towns, and communities. On December 13, 1977, the interim program, which applies a portion of the performance standards of the Act, was promulgated. Then on September 18, 1978, the proposed permanent program was published for public comment. Finally, on March 13, 1979, the final permanent program was promulgated and the States were given a period of time to submit their programs for approval.

Jan 1, 1986

By R. L. Guerguerian

Nowadays, most grinding mills driven by a wrap-around ring motor are operating successfully. Some of the earlier problems could be attributed to the lateral stiffness and stability of their bearings. As a result, modifications to the bearings included the rearrangement of the shoes, or the addition of more shoes, closer to the horizontal centerline. This technical paper reports a study of the effects of bearings on the lateral stiffness of grinding mills driven by a wrap-around ring motor. The discussions cover the design of the four shoe trunnion bearings and examine the effects of the angular location of the shoes.

Jan 1, 2000

By Steve Kral

For an industry that provides more than half of the nation’s energy needs, the U.S. coal industry still attracts negative publicity. However, the nation’s energy appetite continues to increase. And political leaders and the public are beginning to understand that alternative fuels will not be enough to keep up with that appetite. Does that mean the nation will now embrace the coal industry? No, according to speakers at the Rocky Mountain Coal Mining Institute (RMCMI) meeting. The industry still needs to sell the public on coal’s advantages over other fuels. And the industry must continue to develop technology that will allow coal to meet and exceed strict clean air and clean water regulations.

Jan 1, 2002

By C. J. Bise, D. A. Poukhovski

Two integral components of the 30 CFR 48 training requirements mandated for new miners, newly employed experienced miners, and the annual refresher training of all miners are hazard recognition and prevention of accidents. In these categories, instruction shall include the recognition and avoidance of hazards present in the mine, and a review of accidents and their causes. Unlike instruction preparation for fact-based material, program development for hazard recognition places a particular challenge before safety-training specialists because they are often limited in their ability to adequately gauge the trainees' levels awareness prior to training. Further, they must also assure that the training is relevant, and it is presented in a thought-provoking manner. Computer-based instruction is particularly well suited for assisting trainers in developing hazard- recognition topics because it can be used in pre-training and post-training modes for assessment of training effectiveness, in addition to use as a presentation tool. Therefore, this paper will present a recent approach developed at Penn State to apply this technology for assessment and instruction of accident prevention through hazard recognition, with an application prepared for surface coal mines.

Feb 24, 1997

By S. Janisko

Studies have linked long-term inhalation of diesel exhaust with adverse health effects such as cardiovascular disease, cardiopulmonary disease, and lung cancer. Diesel exhaust levels in underground mines can approach 100 times the environmental level and are therefore monitored closely in the mining industry. Elemental carbon (EC) (a product of diesel combustion commonly referred to as ?soot?) has proven to be a good indicator of diesel exhaust levels. The current procedure for measuring EC levels involves taking personal samples from a mine worker?s breathing zone and/or stationary samples in various parts of the mine and subsequently sending these samples to a lab for analysis by NIOSH 5040 method. Unfortunately, the whole process can take up to several weeks to complete. To address the problem of waiting weeks for results, NIOSH?s Pittsburgh Research Laboratory is developing a portable device for measuring levels of elemental carbon. This optical device takes a continuous sample of air in the surrounding environment and measures the absorbance of light passing through a filter that collects diesel exhaust particulates within the instrument. This technology can provide a near real time measurement of EC with accuracy within 10% error. The ability to take near real time measurements, combined with the instrument?s portability (currently small enough to be worn on a miner?s belt), makes this device extremely useful in the mining industry.

Jan 1, 2009

With unprecedented worldwide growth and increasing global demand for energy expected to swell by 60 per-cent in the next two decades, mining matters as much now, if not more, than it ever has. This was the consensus at the 110th Annual National Western Mining Conference presented by the Colorado Mining Association, Feb. 12-14 at the Westin Hotel in Denver, CO. The role of coal ? America?s most abundant energy source ? the future of uranium and its possible resurgence in the energy marketplace, the skyrocketing value of gold as well as the issues of health, safety, climate change, legislation and government?s role in mining were all discussed during the three-day conference that operated under the banner of ?Mining Matters.? Barbara Filas, chairperson of the 110th National Western Mining Conference, president of Knight Piesold Co. and former SME president, welcomed the record crowd with an inspiring speech in which she pointed out that although ?most normal folks don?t know what role mining plays in their everyday life, mining does matter. ?Our industry,? she said, ?matters to Colorado. It matters to Colorado because it is a $3-billion industry. It matters to the 13,000 people who are employed directly or indirectly by the industry and it matters to schools that receive more than half of the royalties that are generated by mining.? During discussions of mining?s place in Colorado, the western United States and the world, special attention was paid to coal, uranium and the future of energy. ?It is time to rethink our perceptions about coal,? said Mark A. Smith, president and chief executive officer of Chevron Mining Inc. He spoke during the opening reception in a presentation titled, ?Coal to Liquids: Bridging America?s Energy Gap.? Although coal is America?s most abundant, and cheapest energy source, it is also one of the most scrutinized because of the pollution it causes and recent, and heavily publicized, tragedies that have claimed the lives of some who mine it.

Jan 1, 2008