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By James P. Rider, Charles D. Taylor, Edward D. Thimons

Research was conducted to investigate how ventilation of a mining face is affected when scrubber flow is greater or less than intake flow. Tests were conducted in a full-scale surface test gallery built to simulate a mining entry with a continuous mining ma- chine at the face. Methane gas was released at constant flow at the mining face. Gas measurements taken at six locations near the face were used to evaluate how well the face was being ventilated. Increasing scrubber flow resulted in lower methane levels even when scrubber flow was much greater than intake flow.

By James P. Rider, Charles D. Taylor, Edward D. Thimons

Research was conducted to investigate how ventilation of a mining face is affected when scrubber flow is greater or less than intake flow. Tests were conducted in a full-scale surface test gallery built to simulate a mining entry with a continuous mining ma- chine at the face. Methane gas was released at constant flow at the mining face. Gas measurements taken at six locations near the face were used to evaluate how well the face was being ventilated. Increasing scrubber flow resulted in lower methane levels even when scrubber flow was much greater than intake flow.

Jan 1, 1997

By Keith G. Wallace

Coal mine ventilation systems are often subject to high leakage rates. As a result, changes in airflow resistance will strongly affect the efficiency with which air is delivered to the working place. One major source of airflow resistance is the line brattice used to direct air from the last open crosscut to the working face. Because it is a great distance from the fan, the resistance of the line brattice can result in more overall leakage than an equivalent resistance closer to the fan. Substituting auxiliary fans for brattice eliminates this source of resistance, with improvements in system efficiency and cost. Also, in some mines, the leakage that leads to spontaneous combustion can be reduced. The benefits obtained by several different brattice and fan substitutions have been studied by Mine Ventilation Services, Inc., under contract to the Bureau of Mines. Changes in main fan duty were compared with additional costs associated with auxiliary fans. Results indicate that in some circumstances, considerable leakage reductions and cost savings are possible.

Jan 1, 1986

By M. Dupuis

It has been previously demonstrated [1,2] that using selective collector bar rodding has a big impact on the uniformity of the current density at the top surface of the cathode block and hence on the intensity of the horizontal current in the metal pad, The present study investigates the impact of using selective collector bar rodding on the MHD stability of a 500 kA aluminium electrolysis cell, For this purpose the recently developed MHD package for the aluminium reduction cell time dependent behavior is used.

Jan 1, 2005

By M. Nambiar

Due to the remote locations of the mining projects and the demand for long transmission lines to provide electrical power, mining sites often operate with poor network power quality and low short circuit capacity. In order to cope up with this situation, more and more mining projects are considering the installation of appropriately designed Synchronous Condensers(SC) together with Power Factor Correction and Harmonic Filter System(PFC&HFS). The installation of these power quality equipments is viewed as a technological advancement in the mining application. An adequate level of short circuit power is essential and has to be ensured for the safe and reliable operation of especially large cycloconverter driven gearless mill drive systems used for grinding application. Increase in plant short circuit power is generally achieved by lowering the impedance of the supplying network. The SC also provides smooth voltage control during mill starting or major load trips, thereby regulating the plant voltage within the required limits. This paper will explore the impact, technical advantage and reasoning for the selection of the advanced hybrid technology mentioned above, in order to cope with the power system challenges for future mining projects. It also highlights the potential problems and how to address them carefully.

Feb 23, 2014

By M. Nambiar

Due to the remote locations of mining projects and the need for long transmission lines to provide electrical power, mining sites often operate with poor network power quality and low short-circuit capacity. To cope with this situation, more and more mining operators are considering the installation of appropriately designed synchronous condensers together with power factor correction and harmonic filter systems (PFC & HFS). The installation of such power quality equipment is viewed as a technological advancement in the mining application. An adequate level of short-circuit power is essential and has to be ensured for the safe and reliable operation of especially large cycloconverter-driven gearless mill drive systems (GMDs) used for grinding. This paper explores the impact, technical advantage and reasoning for the selection of this advanced hybrid technology to cope with the power system challenges of future mining projects. It also delves into the potential problems and how to address them.

By Manoj Khandelwal, Bright Akuinor Tsidi, Newton Amegbey, Daniel Mireku-Gyimah

This study emphasizes the importance of understanding the factors that influence the throwing of flyrock in mining operations, a significant hazard to both workers and nearby structures. Moreover, it highlights how blasting engineers, when estimating flyrock occurrences and their travel distance, typically rely on input parameters such as powder factor (PF), hole length (HL), subdrill (SD), spacing (S), hole diameter (D), burden (B) and stemming length (ST), while overlooking crucial factors like velocity of detonation (VOD) and charge per bank cubic meter (CPBCM). Through analysis using support vector machine (SVM) modeling in MATLAB, the study underscores the impact of including or excluding VOD and CPBCM on flyrock throw distance.

Jul 1, 2024

By Manoj Khandelwal, Bright Akuinor Tsidi, Newton Amegbey, Daniel Mireku‑Gyimah

One of the ambient effects of production blasting is flyrock. To effectively manage flyrock throw distance in mining, there is the necessity to successfully envisage blasting output without sacrificing the hazardous impact of flyrock which may result in fatality and operational shutdown. For flyrock throw distance prediction, velocity of detonation (VOD) and charge per bank cubic meter (CPBCM) are not usually included. This paper focuses on the use of support vector machine (SVM) regression to ascertain the impact of VOD and CPBCM on flyrock throw predictions. The machine learning models were linear support vector machine (LSVM), quadratic Gaussian support vector machine (QGSVM), fine Gaussian support vector machine (FGSVM), medium Gaussian support vector machine (MGSVM), and cubic Gaussian support vector machine (CGSVM). The outcome indicates that FGSVM was the most sensitive with a 4% improvement when VOD and CPBCM were included. As a result, the LSVM model provides a suitable AI competitive alternative tool for flyrock throw prediction in mining operations by incorporating VOD and CPBCM.

Feb 10, 2024

By Ken Mills

A program of stress change and roadway deformation monitoring was undertaken to measure the forward abutment load distribution about a retreating longwall panel at Dartbrook Mine. The results of this monitoring allow roadway conditions observed at various stages of mining to be ranked according to the estimated vertical stress they have experienced. This ranking also provides a means to predict and visualise future roadway conditions at various stages of mining. This paper presents the results of the monitoring and describes the approach developed to predict future roadway conditions. The monitoring results show the vertical stress distribution associated with the front abutment from a longwall goal decreases exponentially away from the goaf edge. The vertical stress distribution peaks at the goaf edge at 5 to 6 MPa stress increase and decreases to 1 MPa within 50 m becoming imperceptible beyond 100 m By scaling this measured distribution to reflect the loading environment, the vertical stress can be estimated for different overburden depths and different stages of mining. Photographs of roadway conditions at particular vertical stress levels provide a way to visualise roadway conditions at various stages of mining in the future

Jan 1, 2000

By AIME AIME

OVER-ALL operations of the oil industry, as measured by production of crude oil and consumption of products, are almost exactly of the same magnitude as a year ago. Does this mean that the great oil industry has been undisturbed by the war? Has this industry, so vital to the prosecution of the war and to the maintenance of our way of life, been unaffected in its operations? No indeed - changes within the industry are great. It has been called upon to revamp its trans¬portation methods so as to move about one fourth of the total amount of crude and refined products by railroad tank car instead of by ocean-going tankers. Its fundamental internal economy, based on maximum gasoline yield from a barrel of crude, has been relegated to memories of the past. Rationing of oil products, which has been forced upon us in face of an abundant supply, is not only disagreeable medicine but is in itself completely disruptive to the marketing end of the-business.-

Jan 1, 1942

By Travis S. Wellman, Jon C. Volkwein

The Bureau of Mines conducted a study to assess the impact of a directional water spray system on a unique single inlet dust scrubber on a low profile mining machine. Tests were conducted in a full scale model mine using a Joy 12 CM 10-AA continuous mining machine. Tracer gas was introduced at the face and concentrations of the tracer gas were monitored at the face and in the return. Various parameters included: mining position, depth of cut, brattice setback and combinations of scrubber, directional sprays or symmetrical sprays. Results indicated that either directional or symmetrical water spray configuration improved the ventilation effectiveness of the scrubber by a factor of 2 to 3. Average face ventilation effectiveness (FVE) values for all testing of the scrubber and directional sprays were 0.95, versus 0.37 for a standard 6 m (20-ft) blowing curtain without sprays. No FVE values were less than the standard 6 m (20-ft) blowing results.

Jan 1, 1989

By Kurt Bryan, O&apos

The crushing and milling of mineral bearing ores can now be accomplished more efficiently through the application of WaterFlush technology. WaterFlush crushing has reduced capital and operating costs for the processing of a lead/zinc ore in South America. Similar benefits can be expected in the processing of other ores. WF cone crushers offer improved performance over conventional cone crushers. Performance improvements include the ability to crush wet and sticky ores, increased reduction ratios and greater production of flakier and finer products.

Jan 1, 1989

By Sai Phaninder Reddy Chaganti, Corrina D. Beaven

This study investigates the effect of reagent type, dosage, and pH on flotation kinetics and copper recovery for secondary sulfide ore with elevated clay content. The primary objective was to determine whether Xanthate performs comparably to or better than the currently used primary collector, Thiophosphate. Approximately 80 kg of ore was collected from three blast holes and systematically prepared through drying, crushing, grinding, and flotation testing. Grinding tests were conducted to establish optimal grinding time and lime consumption for pH control, achieving a target particle size distribution in 13 minutes and 30 seconds. Elemental and mineralogical analyses using X-ray Fluorescence (XRF) and X-ray Diffraction (XRD) identified a copper content of 0.36% and significant clay presence, affecting flotation performance. Fifteen flotation tests were performed under controlled conditions, with variations in reagent dosages. Control tests confirmed reproducibility, with recoveries around 80–82%. Increasing the pH did not improve kinetics or recovery, making higher pH adjustments economically unjustifiable. Adjusting the Thiophosphate dosage yielded the best recovery of 83%. Xanthate collectors, tested both as tertiary additives and as replacements for Thiophosphate, delivered comparable or superior recoveries—up to 91.5% in plant tests—and demonstrated faster flotation kinetics, even under high-clay conditions. These findings highlight Xanthate’s reduced sensitivity to clay, potential for lower dosage requirements, and operational benefits such as improved selectivity and circuit efficiency, validating its role as a cost-effective and alternative for processing complex sulfide ores.

Feb 22, 2026

By Kelly F. Bailey

Introduction On June 20, 1986, the Occupational Safety and Health Administration (OSHA) published revised asbestos exposure standards for general industry and construction. The standards reflect OSHA's attempt to adequately control workplace exposures to minerals it considers carcinogenic - minerals capable of causing or contributing to cancer. These standards specifically identify asbestos as: chrysotile, an asbestiform serpentine mineral; and the amphibole minerals amosite, crocidolite, tremolite asbestos, actinolite asbestos, and anthophyllite asbestos. Each of these has a more common nonasbestos mineral analog that exists in nature in a crystalline, blocky shape rather than the hair-like or fibrous shape of asbestos. The mineralogical names for three of these nonasbestos minerals are unique: antigorite for chrysotile, cummingtonite-grunerite for amosite, and riebeckite for crocidolite. The other three nonasbestos analogs do not have unique mineralogical names. They are simply designated as actinolite, tremolite, and anthophyllite without the word asbestos following their names. The 1986 OSHA standards not only cover exposure to the six asbestos minerals, they also cover specifically the nonasbestos forms of actinolite, tremolite, and anthophyllite (AT&A). The new standards regulate these minerals exactly like asbestos (OSHA, 1986). The construction aggregate industry views this as a major problem because these nonasbestos minerals are common amphibole rock-forming minerals in the earth's crust. They exist in small quantities over large areas of the United States (Kuryvial et al., 1974). These minerals, unlike asbestos, are not mined for a specific commercial purpose. They are unavoidable components in much of the aggregate used for construction throughout the US. They are also common in the gangue material of metallic ores. There are areas of the US where amphibole-bearing bed¬rock is common. Not every rock mass in these areas contain amphiboles, however. It does mean, though, that amphiboles are physically compatible with many of the rocks in those areas. And given the correct geochemical conditions, they will be present primarily in the nonasbestiform variety. In addition, these amphiboles will probably exist in the natural drainage system, sand and gravel deposits, stream sediments, lake shores, valley basins, or ordinary beach sand within these areas. There has been little quantification of nonasbestiform AT&A in dusts and soils in the US. This is not surprising since these nonasbestiform minerals are not commercially valuable. However, an example of the pervasive nature of these minerals can be found in a 1981 Geological Society of America publication where about 0.7% tremolite-actinolite was found in the desert dust in and around Tempe, AZ (Pewe, 1981). Since OSHA standards treat these common nonasbestos minerals as carcinogens in the same way as asbestos, large natural areas in the US are implicitly being labeled as hazardous by OSHA. When a substance is identified as a carcinogen, another OSHA standard comes into play, the Hazard Communication standard. There are also right-to-know laws in 9 states that essentially duplicate this federal standard. These standards require that a product containing 0.1% or more of an OSHA-designated carcinogen be labeled as such (OSHA, 1983). This means that much of the stone and sand gravel products occurring naturally and mined in the US could be labeled a carcinogen when, in fact, they are not. The National Stone Association (NSA) and the domestic construction and mining industries believe that OSHA has seriously erred. The NSA has studied the health, mineralogical, technical, economic, and legal basis for OSHA's action. These studies concluded that there is no justification for the agency regulating nonasbestos minerals as if they were asbestos. Health issues The preamble to OSHA's 1986 asbestos standard states that evidence for asbestos-like health effects from exposure to nonasbestiform varieties of AT&A is inconclusive (OSHA, 1986). The fact is, not only are the data inconclusive, they are nonexistent. During 1986-1987, NSA's occupational health and epidemiology consultant, Environmental Health Associates (EHA), reviewed all available health studies related to AT&A. EHA found evidence that malignancies in both experimental animals and humans are associated with the asbestos forms of these minerals. No experimental or epidemiological evidence was found that indicated such pathogenic effects occur from exposure to nonasbestiform varieties of these minerals. There are relatively few scientific studies of the health effects of exposure to nonasbestiform varieties of AT&A. In three different animal studies, exposure to either nonasbestiform tremolite or actinolite did not result in pulmonary fibrosis on in excess tu-

Jan 11, 1988

By James W. Evans, Brian R. Wildey

"Carbon has been the principal reducing agent in producing metals for centuries. Carbon is an inexpensive reducing agent, but also an effective one, as any undergraduate who knows her Ellingham diagrams is aware. Even in the production of aluminum, an electrolytic process, carbon consumed at the anodes serves to reduce the voltage of the Hall-Héroult cell. The interest in reducing the amount of anthropogenic CO2 has led to this examination of whether a switch to hydrogen as a major reductant is feasible and economic. The main source of hydrogen is natural gas and its production entails the generation of CO2; however, that CO2 is more easily captured than, say, the CO2 leaving an iron blast furnace. Calculations and speculations lead to conclusions about whether there is significant benefit to be obtained from such a radical change in our way of producing metals and the approximate cost of such change.IntroductionThe 1991 paper by Forrest and Szekely1 was one of the first to examine the impact of CO2 emissions from the primary metals industries on global climate change. These authors compared data from 1968 and 1985 and reported a drop in carbon emissions from 115.8 million tons to 65.6Mt over this period, the latter figure representing approximately 1% of the world’s greenhouse gas emissions. Much of this reduction was due to a drop in steel output (with carbon emissions increasing within the aluminum and copper industries in this period) but some were due to technological changes such as increased use of continuous casting. A more recent paper on CO2 emissions, focused on the steel industry in Japan, is that of Ariyama and Sato2. These authors report CO2 emissions of 182.4Mt from the Japanese steel, industry in 2003, down from 194.8Mt in 1990. The former represents 14% of the GHG emissions for Japan in 2003. Much of this emission is from ironmaking and the authors break these emissions down into"

Jan 1, 2008

By J. H. Starkey

Large differences between macro and micro grindability relationships have been discovered for mill design measurements using the patented SAGDesign(TM) test. Crushing, Rod and Ball Mill Wi tests, and breakage parameter measurements have previously been used to design SAG mills but have not revealed the true magnitude of these differences. A SAGDesign(TM) test measures the SAG/Bond Wi Ratio (defined below) for every sample tested and gives a good design result because the F80 of the SAG stage test feed is 19 mm and because the test includes a Bond Ball Mill Work Index on SAG ground ore. Good flotation operation demands properly sized grinding mills and steady feed to the flotation circuit.

Jan 1, 2009

By N. A. Frazier

The technology for using limestone or lime to scrub SO2 from power-plant flue gas has significant implications to the limestone industry. A brief status report on these processes will be made, possible process requirements on the limestone properties will be reviewed, and projections on the buildup of demand with respect to time will be reviewed. Disposal problems inherent with the use of these throwaway processes will also be summarized. Given a viable technology, relations among (1) distance of power plants from low- and high-sulfur coal and limestone deposits, (2) modes of handling and transporting immense tonnages of bulk material-coal and/or limestone, and (3) regional air-quality standards are some of the factors which will ultimately determine the demand for limestone. A discussion of these factors will be presented, with the intent of identifying geographic regions where significant increases in production can reasonably be expected.

Jan 1, 1974

By Felipe P. D. Lopes, Jr. dos Santos, Sergio N. Monteiro, Frederico M. Margem

"Continuous and aligned fiber composites provide the highest possible reinforcement for a polymeric matrix. In particular, the impact resistance is significantly increased in comparison with a low energy absorbed brittle polymer. For this reason, investigations have been carried out with both synthetic and natural fibers as a way to improve the toughness of polymeric composites. Among the natural fibers, ramie was not yet been studied for its reinforcement effect to make tougher polyester composites. Thus, the present work assesses the impact toughness of polyester composites incorporated with different amounts of ramie waste fibers.IntroductionIn most engineering and other technological areas, the use of materials associated with low energy processing conditions is gaining attention for the possible environmental benefits. This offered an incentive towards the substitution of natural renewable and biodegradable materials for the traditional energy intensive synthetic materials [1]. Natural fibers from both origins: animal, such as silk and wool, and vegetable, such as cotton and jute, are typical examples of those environmentally friendly materials. Low cost and highly reduced processing machinery wear are important advantages of the natural fibers over the most common synthetic ones such as glass fiber and nylon. For these reasons, polymeric composites reinforced with natural lignocellulosic fibers have nowadays been the subject of investigation [2,3].The mechanical strength is one important property of lignocellulosic composites to access the possibility of uses like structural materials for building parts such as doors and panels, as well as furniture. In this case, mechanically strong fibers like sisal, jute, curaua and ramie [4-7] are most convenient. Moreover, the relatively low fiber/matrix interfacial shear stress in these composites is associated with higher impact energy. In fact, a greater energy has to be expended for the rupture of a weak interface. The many cracks that are formed by impact tend to branch during the fiber pullout from the matrix [8]. A larger number of cracks correspond to a greater fracture surface and consequently higher toughness."

Jan 1, 2008

By Paul Worsey, Randall Franklin

This paper is based on an undergraduate research project undertaken for the explosives emphasis in the UMR mining engineering degree program by the first author. The purpose of the selected research topic was to investigate the impact sensitivity of commercial detonators to determine their relative safety for handling and how much abuse they can take without accidentally firing. A modified BAM tester was used for the investigation. Both electric and non electric detonators were impacted at incremental positions along their length to determine the relative effect of their various components. Repeat impact tests were also conducted to see how a damaged cap would react to repeated abuse. The results indicate that it takes a significant amount of impact energy to initiate commercial detonators. They also indicate that repeated abuse can increase sensitivity. Modern commercial detonators appear to be relatively insensitive to impact (an order of magnitude above RDX in the standard BAM test) and this is mainly due to their construction. This explains why damaged caps with exposed powder are more sensitive. Their measured insensitivity correlates with rough handling not being a major cause of blasting accidents.

Jan 1, 2004

By M Doran

The Olympic Dam mine utilises 1.1 m to 1.4 m diameter raise bores for generating the initial slot void for most production stopes. Slot raise bores generally span two development levels ranging from 30 m to 50 m in height. Raise bores are reamed upward and typically leave a cap of rock equivalent to two times the raise bore diameter on the drill level (minimum 3 m). This provides safe access over the cap for subsequent production activities. It is therefore critical to ensure robust falling object protection for personnel accessing underneath, and in the vicinity of the raise bore void on the lower level. Recently, a number of mesh failures have occurred at Olympic Dam as a result of falling rock from the underside of the cap and raise walls. In addition, as Olympic Dam transitions to deeper and more challenging ground conditions, rockfall-off onto the raise bore protection mesh is anticipated to increase in frequency. This paper discusses the evolution of raise bore protection mesh used at Olympic Dam and presents results from recent site-based drop testing. This impact testing was carried out using a built for purpose object to replicate point loading and shear failure of mesh wires. Testing was also carried out on an improved mesh design which utilises two layers of Geobrugg high-tensile MINAX mesh. Results from the drop testing suggest an improvement in performance of the raise bore protection mesh is realised with the updated design.

Mar 29, 2023