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By Thomas Novak, Sampurna Arya, Joseph Sottile

Dust generation and its dispersion in a longwall mine pose significant health and safety issues. The concern is prominent at both the working face, where coal excavation exposes workers to high dust concentrations, and also in the return, where float dust accumulates. To address this issue, researchers at theUniversity of Kentucky designed and fabricated a flooded-bed dust scrubber integrated into a full-scale physical model of a longwall shearer. This mock-up was installed in the longwall test gallery at the Pittsburgh Research Laboratory (PRL) of the National Institute for Occupational Safety and Health (NIOSH). A full-factorial experiment was designed to measure the effectiveness of the scrubber on dust capture. Test results indicated dust reduction of up to 57% in the return airways. This paper presents the development of a computational fluid dynamics (CFD) model and its validation by comparing the simulation results against the experimental results. The CFD simulations show good agreement with experimental results with differences between + 6.9 and − 9.7%. The validated CFD model was used further to predict the scrubber performance under additional operating conditions, resulting in a dust reduction of up to 66.5%. With this level of success, the scrubber concept can be a game changer for the mining industry, and it can be utilized to improve health and safety in longwall mines.

May 26, 2020

By Wolfgang Guetter, Wolfgang Weber

The upgrading project for two hydropower plants in Slovenia, Europe, requires two new pressure tunnels: Plave II (5.9 km Flysch) and Doblar II (3.6 km Limestone). It is the worldwide largest application of the Double-Shield TBM technology combined with an extremely thin-walled monoshell honeycomb lining system. The first drive has been completed by end of June 2000 achieving best performances of 50m/d and almost 1,100m/mth. In September 2000 the TBM started the second tunnel without any required adjustments due to geological or other reasons. Another 52m/d have been bored already within one production day of two 8 h shifts achieving a maximum penetration rate of more than 6m/h. The completion of the Doblar drive can be expected by February 2001.

Jan 1, 2001

Narrow vein mining, with enough challenge and also where the cutting edge technology can be applied, is still a very important and exciting portion of the mining industry. Based on the deposit characteristics, the most flexible mining method, cut and fill, has been being tested mining this high grade Northern Nevada property, Hollister, since the year of 2008. In the last three years, 254,000 tons of ore were hauled out of the portal and 23,000 feet of development were excavated underground with the winning of several safety and environmental awards. Together with mine geology, the essential segments include mining cycle, ground control, ventilation, grade control and backfill method in cut and fill stopes were covered in this paper.

Jan 1, 2012

By James M. Barker

No commodity agreements now exist for sulfur and a lack of reference to sulfur commodity agreements exists in the literature. Law (1975) made a passing reference to sulfur as one of a group of commodities where "there have been additional control efforts of various types." Clearly, sulfur was a candidate, at least conceptually in the past, for some form of commodity agreement and the following discussion centers on the world sulfur market of the early 1980's in this context. GENERAL THEORY OF COMMODITY AGREEMENTS The upsurge in demands for commodity agreements seen in the last decade or so stems largely from agitation by the less developed countries (LDC) for better economic treatment by more developed countries (MDC). Several economic factors, real or imagined, adversely affect the LDC's as follows (MacAvoy, 1977): 1) variable demand in MDC's causes wide fluctuations in commodity prices which hurt the economies of commodity producers, who are often LDC's although consumer economies may also benefit from more predictable prices; 2) a general decline of commodity prices relative to the price of manufactured goods which hurts commodity producers in their balance of trade while their stocks and overcapacity rise; 3) instability of LDC economies enhanced by the above factors lowers internal stability, inhibits foreign investment, and retards economic growth; and 4) a lack of self respect when dealing with developed countries o, following the OPEC lead, LDC producers want the stature related to cartel market power.

Jan 1, 1985

By José A. Rios, José A. Vidalôn

The case study of a highland area in the Central Andes of Peru, where many abandoned polymetallic mines are found, is presented. Some of these mines generate metal leaching and acid rock drainage (ML/ARD) or have potentially ARD generating (PAG) tailings/waste rock storage. Effluents are discharged into the first of two lakes in line, which act as reservoirs for irrigating an important valley in the desert coastal region. Drainage fees, their relationship with the deposit and the solid-wastes mineralogy are discussed, as well as variations in water and sediments composition, the benthos, and the aquatic/riparian flora/fauna in these lakes.

Jan 1, 2000

Ceremonies for the induction of five mining industry pioneers into the National Mining Hall of Fame will be on Sept. 12, 2009 at the Charles F. Barber Pavilion of the Museum Convention Center in Leadville, CO. The five inductees are: Paul A. Bailey, 82, Richard T. Moolick, 89, William Braden and Alonzo Pawling and Henry Harnischfeger. Paul A. Bailly was president of Bear Creek Mining Co., the U.S. exploration subsidiary of Kennecott Copper, from 1961 to 1967. In 1968, he joined Occidental Petroleum Corp. and was tasked with creating the company?s international mining division, Oxymin, which he led as president through 1983. During his distinguished career, Bailly participated in numerous significant mineral discoveries, developed a new exploration philosophy and made important additions to the mineral exploration literature. William Braden was the first to recognize the immense potential of the El Teniente orebody in Chile. He founded Braden Copper Co. and developed the El Teniente Mine which now, 100 years later, remains the world?s largest underground copper mine. Braden?s endeavor survives to-day as the El Teniente division of the Chilean state copper company, CODELCO. T. (Dick) Moolick established a lasting legacy in the mining industry, first during a 35 year career with Phelps Dodge Corp. and then as the driving force in establishing the National Mining Hall of Fame and Museum in Leadville. The Hall of Fame and Museum ? a monument to the memory of the men and women who pioneered the discovery and development of the United States? natural resources ? has become one of the fi nest museums in the western United States.

Jan 1, 2009

By J. J. Carlson

Studies were carried out to determine whether filtration rate changes observed in an iron ore concentrator were due to variations in particle shape. It was confirmed that ores mined from different locations differed in filtration rates by as much as 60%. However, when image analysis was used to quantify the shapes of the individual particles in the filtration feed, it was found that the particle shapes showed almost no variation, and the shapes did not correlate with the filtration rate. It was also determined that the filtration rate variations were not caused by changes in particle size distribution. These results suggest that the differences in filtration rate are due to factors other than size and shape, such as surface chemistry.

Jan 1, 2008

By J. E. Bernick, J. Davies

This paper describes the design and construction of a 22.86 m (75 ft) long jacked tunnel, which was successfully installed, despite difficult mixed face conditions at Metro-North’s Westport Station, in Connecticut in the fall of 2003. The tunnel utilized what is believed to be, the first application of a steel grillage system within the United States. This grillage was installed before the jacking started and allowed the tunnel to be jacked under four live railway tracks, which included the Acela high speed line, without affecting train operations. The clearance between the top of the tunnel and the rails was only 0.9 m (3 ft).

Jan 1, 2005

By D. R. Wilburn

his summary of international mineral exploration activities for the year 2011 draws upon available information from industry sources, published literature and U.S. Geological Survey (USGS) specialists. The summary provides data on exploration budgets by region and mineral commodity, identifies significant mineral discoveries and areas of mineral exploration, discusses government programs affecting the mineral exploration industry and presents [ ] analyses of exploration activities performed by the mineral industry. Three sources of information are reported and analyzed in this annual review of international exploration: 1) budgetary statistics expressed in U.S. nominal dollars provided by Metals Economics Group (MEG) of Halifax, Nova Scotia; 2) regional and site-specific exploration activities that took place in 2011 as compiled by the USGS and 3) regional events including economic, social and political conditions that affected exploration activities, which were derived from published sources and unpublished discussions with USGS and industry specialists.

Jan 1, 2012

By M. Paul

"INTRODUCTION In 1990, the uranium production of SDAG Wismut in East Germany was stopped. 45 years of inconsiderate destructive exploitation had scarred both landscape and nature. With the “Wismut law” which came into force in December 1991, the Federal Republic took responsibility of the remediation of the legacies from former uranium ore mining and milling in Saxony and Thuringia. A unique opportunity turned out in order to remove environmental damage, to enhance the life quality of the local population, to shape new landscapes and to advance the economic restart. (1) The results of nearly 25 years of remediation activity are evidence that this opportunity was used at all former SDAG (Sowjetisch-Deutsche Aktien-gesellschaft) Wismut sites. The reference project “Wismut“ has evolved into a joint project of all parties involved and radiates beyond the affected regions. This is particularly reflected by the Know-how transfer starting from Wismut and the increasing activities for third parties abroad.WATER MANAGEMENT AT WISMUT REHABILITATION Within the Wismut project, water management and conventional technical water treatment are by far the most cost-intensive long-term tasks of the remediation programme. Over the medium term, there is no viable alternative to the operation of active systems to catch and treat contaminated mine waters at the Ronneburg, Schlema, Königstein, Pöhla, Seelingstädt and Helmsdorf sites. Based on the status quo, this paper outlines the key issues of the Wismut GmbH water management strategy over the medium and long term. It is focused primarily on achieving protection goals for potentially impacted water bodies in the surroundings of Wismut sites and on optimising associated remediation expenditures as well as on creating the prerequisites for achieving low post-remedial care and maintenance or walk-away system status over the long term. (2) The applied mining practices during the active SDAG Wismut period have not been up to the high standards of modern mining operations and their requirement to leave former production premises and deposited residues in a condition that was not only physically but also chemically stable. Rather the emission of mine and seepage waters laden with high acidity, metal and salt content is a frequent corollary and difficult legacy of historic mining and processing operations (4, 5). As a consequence, the control or mitigation, respectively, of environmental impacts associated with contaminated mine waters ties up enormous public resources worldwide (6, 7)."

Jan 1, 2016

By Shaoyang Yan, Xinming Chen, Huazhe Jiao, Huaibao Chu, Chang Wang

In terms of the technical problems of rib spalling in large mining height coal face, a long-distance advanced pre-grouting layer flexible reinforcement technology is proposed in this paper. Based on the mechanism and failure mode of rib spalling in the coal face, the mechanical properties of the aluminum plastic composite pipe were analyzed by using the tensile and compression experiment. The deformation and strength characteristics of “flexible pipe + grouting” specimens were studied by uniaxial compression test, splitting test, and shear test. The UDEC numerical simulation software was used to simulate the reinforcement effect of “flexible pipe + grouting” at different positions. Combined with the field application, the feasibility of long-distance advanced pre-grouting layer flexible reinforcement technology was verified. The test results show the following: The coal face has the characteristics of brittle and large deformation. The aluminum plastic composite pipe has the characteristics of good elongation and tensile strength, which can endure the large deformation of the coal face. The “flexible pipe + grouting” can improve the tensile and shear strength of coal. The UDEC numerical simulation analysis indicated that the grouting hole layout of “flexible pipe + grouting” has a significant difference in the reinforcement effect of the coal face. Compared with single row grouting reinforcement, the reinforcement effect of double row grouting holes 1.5 m and 3.0 m away from the roof is better. According to the field application, it is feasible to use aluminum plastic composite pipe as a flexible grouting pipe to reinforce coal seam with 80–100 m long-distance pre-grouting. Long-distance advanced pre-grouting layer flexible reinforcement technology can improve the daily production of coal and reduce the support cost of the coal face. As a new method of reinforcement, long-distance layered flexible reinforcement has a significant effect on the prevention and treatment of rib spalling in large mining height coal face.

Sep 27, 2022

According to the classification of water conservation mining in shallow coal seams in China, when the ratio of the impermeable layer thickness to the mining height is less than 18, the mining belongs to the category of special water conservation, and the strip backfilling mining method is employed. This study is based on the geological conditions in northern Shaanxi. By analyzing the stability of the impermeable layer, the stability criterion of the impermeable layer was developed. The study also investigated the compositions and properties of the backfilling materials. The results show that reasonable subsidence of the impermeable layer is allowed during mining under the basic precondition (upward cracks and downward cracks are not connected).

Jan 7, 2020

By William C. Dixon

Since the mid 60's, several haul cycle simulation programs have been developed. However, most of these programs are believed to employ the continuous, rather than the discrete, event-oriented simulation approach to determine the haul cycle times. This paper describes the recently developed haul cycle simulation approach where time is advanced in varying amounts only as the system changes occur. This approach results in greater computational accuracy and increased computational efficiency. The program is written in FORTRAN and requires equipment performance curve and haul road profiles as input. Unique program capabilities include the handling of switchbacks and intersections. The program uses a master data file concept in which various haul road profiles found during the mine life can be simulated all in one job submission. The results of the model validation using the actual time study data provided by an open pit mine operator near Tucson, Arizona, are also described in this paper.

Jan 1, 1978

By R. E. Moore

Refractories are unique ceramic materials, which are used in large quantities in steel making furnaces, metal smelting vessels, and glass melting tanks. They are required to possess high thermal shock properties and good slag corrosion resistance as well as creep resistance at high temperatures. Therefore, they are made from very refractory minerals such as lime, periclase, corundum, spinel, and zirconia. Slags are vitreous materials produced as a residue in steel refining processes. They cover a wide range of compositions and may contain pure oxides, silicates, and sulfides as well as fluoride phases depending on the melting and smelting processes. These minerals exhibit spectacular cathodoluminescence color under electron bombardment; therefore, cathodoluminescence (CL) microscopy is found to be a superior technique for the characterization of refractory corrosion by slags. Examples included in this study are (1) reaction of fluorine containing mold slags with ZrO2-C nozzle refractories promoting crystallization of the Cuspidine, Ca4Si2O7(F,OH)2, (2) corrosion of fusion cast refractories in TV panel glassmaking furnaces and formation of glass defects, and (3) reaction of spinel based castable refractories with copper smelting slags.

Jan 1, 2001

By P. Zhang, S. Al-Thyabat

"Phosphate rock contains traces of rare earth elements (REEs) and can be a secondary source of these critical materials as large tonnages of phosphate rock are mined annually. Attention has mostly focused on the extraction of REEs from phosphogypsum, which contains more than 70 percent of the REEs reporting to phosphate concentrate, with only limited work conducted on REE extraction from sand tailings and slime even though they account for 16 percent and 15 percent, respectively, of REEs mined with phosphate matrix.In this work, phosphate flotation tailings were upgraded by gravity separation and froth flotation. Gravity separation was conducted using a laboratory shaking table, while flotation was conducted in a Denver D-12 flotation cell. The concentrated tailings were then leached by nitric acid followed by REE extraction with solvent and ion-exchange resin.The sand tailings were assayed as having 2.6 percent phosphate (P2O5 ) and 198.1 µg/g REEs. It was found that the shaking table could produce tailing concentrate assayed as having 8.6 percent P2O5 and 616 µg/g REEs but with only 20 percent REE recovery, while the froth flotation produced froth concentrate assayed as having 8.1 percent P2O5 and 368.2 µg/g REEs with 63.5 percent REE recovery. Leaching the flotation concentrate with 5.2 M (25 percent) nitric acid followed by extraction with solvent and ion-exchange resin yielded precipitates with REE contents of 0.926 and 0.314 percent, respectively, compared with 0.716 and 0.213 percent when table concentrate was used.IntroductionRare earth elements (REEs) consist of a group of 17 elements: the 15 lanthanides along with yttrium (Y) and scandium (Sc). They are rare not because of their scarcity in the Earth’s crust but because they are rarely found in economic and mineable deposits. REEs are called “seeds of technology” because of their importance to some critical technological industries such as renewable energy, hybrid cars, electronics and batteries. On average, an electric car or a hybrid car contains about 10 kg of REEs (Grasso, 2012; Radhika et al., 2011).REEs are usually categorized into light (LREE) and heavy (HREE). LREEs consist of lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pr), samarium (Sm), europium (Eu), gadolinium (Gd) and scandium (Sc), while HREEs consist of terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), lutetium (Lu) and yttrium (Y). About 200 minerals contain traces of REEs, but only three are considered economically significant: bastnasite, with the formula La,Ce(CO3)F; monazite, with the formula(Ce,La,Nd,Th)PO4; and xenotime, with the formulaYPO4 (Jordens, Cheng and Waters, 2013)."

Jan 1, 2016

By Muhammad I. Kabir

The streamline method of recovery prediction reduces a two-dimensional problem to a bundle of one-dimensional ones. This paper presents the development and application of a novel scaling technique which, when used with a streamline model, causes s bundle of one-dimensional problems to further reduce to a single one-dimensional calculation. The one-dimensional calculation accounts for chemical-rock interactions and the streamline model for areal sweep. The scaling technique significantly reduces computation time, is readily modified to desk-top calculations, and can be applied to both absorbing and reacting species. The work was sponsored by the Interior Department's Bureau of Mines.

Jan 1, 1984

By Davorin Kolic, Harald Wagner

Conventional ground support in accordance with latest state-of-the-art considers proper preparation of geotechnical investigation, structural design, observation during construction and fair risk sharing documents. Depending on the ground, there are different means and methods, reflecting different experiences. The paper is presenting ground support concepts, as mostly used in Europe during the past three decades. It discusses the use of anchors as well as the use of steel arches respectively combinations. It also discusses different applications of plain shotcrete, respectively fibre reinforced shotcrete. As excavation sequence is a major input to create the ground arch, the paper discusses also criteria to create closed ring conditions. Finally deformation criteria will be presented with case histories in order to control stability of the structure.

Jan 1, 2001

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 James Addis, Zoheir Khademian, Marcia L. Harris, Charlie Matthews, Y Zheng

Shale gas wells can sometimes drill through coal reserves. Hypothetically, the caving of the gob from longwall coal mines may deform the shale gas well casing and potentially result in a breach. NIOSH researchers studied the permeability of the surrounding ground strata that may affect the potential for an inflow of gas into an underground mine environment. An overview and comparison of measured permeability values under differing cover depths (147 m and 353 m to the Pittsburgh coal seam) and mining cycle phase will be presented and discussed in this report. The findings highlight data-driven experimental evidence that affect the interaction between gas wells extraction and mining operations that may lead to potentially hazardous environments.

Feb 1, 2025

By Klaus Rieker

Over the last 30 years Wayss & Freytag Ingenieurbau AG has gained a lot of experience in mechanized tunnelling on various major projects. During this period most important developments concerning the machine technology for EPB- and Slurry-Shields have taken place. Since the first application of a hydro shield for the Wilhelmsburg Collector project in Hamburg in the early seventies, several stages of development have led to the current state-of-the-art in mechanized tunnelling. The continuous improvement of TBM techniques allows the execution of high quality tunnelling, particularly with regard to maximum safety and efficiency. The practical experience of the construction companies is of essential importance in order to continue further development and improvement.

Jan 1, 2005