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Blast vibrations induce sounds within neighboring residences. A house wide vibration and sound monitoring system was installed in a West Virginia home which was subjected to blasts at varied distances and direction. Eighty-nine blast events were monitored and analyzed for this case study. Fifteen channels of data were collected including three triaxial geophones, one airblast microphone, one uniaxial geophone mounted to the wall of the house (response channel), and four microphones that recorded CD quality sound waves inside the house. Each of these channels was recorded on the same time reference and scale allowing for direct comparison of the waveforms. The response channel signal was easily separated into ground vibration induced and airblast induced movement due to the differences in their times of arrival. This response channel was then compared to the sounds recorded inside the home to determine which component of blast vibration induced the maximum sound response inside the home. Blasts at distances less than 762 meters (2,500 feet) had maximum sound responses from both ground vibration and airblast. While for blasts beyond 762 meters (2,500 feet), the maximum sound response inside the home was caused by ground vibration without exception. When airblast was identified as the dominant sound generator in the house, the peak amplitude of the sound was directly related to the amplitude of airblast. When ground vibration was identified as the dominant sound generator in the house, the peak amplitude of sound was not related to the amplitude of ground vibration. In these cases, sound amplitude was driven by the conditions present in the house such as loose items, doors, and windows creating sudden peaks from falling or slamming. In the same respect, sound amplitudes varied depending on where the sound was recorded. Different rooms generated very different sounds based on the contents of the room. Findings from frequency analysis showed that the frequency content of sounds inside the house were not related to frequency content of airblast or ground vibration regardless of source suggesting that residents would have difficulty determining the source of blast induced noise in their homes.

Jan 1, 2010

By Richard L. Gordon

Coal supply analysis has since about 1973 become a major activity of many scholars and consulting firms. The present paper is an effort to explain in as nontechnical fashion as possible the state of the art and what implications, if any, the research has for those actually engaged in producing coal or regulating the industry. l The discussion stresses the coal supply side of the models and makes limited comments about other elements in the analysis. To orient the appraisal, it is desirable to recall the features of coal supply that an adequate model should capture. The first considerations are the locational aspects of the industry. Transportation costs can, in some cases, exceed the production costs of coal, and thus any adequate model must incorporate a treatment of the economics of transporting coal from one location to another. A second major issue is that of the heterogeneity of coal; models should treat as well as possible such key differences among coals as their Btu and sulfur content. Third, we recognize that, with given technology and labor, capital, and supply costs, an expansion of the supply of a given type of coal in a specific region will occur only if prices rise. This is the familiar proposition of textbook economics that supply is an increasing function of price. Finally, over time, changes in technology, input cost, and depletion interact to cause changes in the price of given amounts of coal. Economics represents the net effect of this process by a shift over time in the supply curve. During the 1950s and 1960s, the trend was to reduce the production costs of a given output; subsequently costs rose sharply.

Jan 1, 1977

By William J. Miles

For compliance with the Hazard Communication Standard and other federal and state regulations, numerous minerals, chemicals and products need to be evaluated for crystalline silica content at a threshold of 0.1 %. The polymorphs of crystalline silica that can occur in chemical and mineral products are quartz, cristobalite and tridymite. Other natural, industrial and synthetic amorphous silicas and hydrates must be distinguished from these polymorphs to prevent over-regulation in the workplace and environment. A number of industrial silica products are composed of glasses, expanded perlite, diatomite, slags, and precipitated and fumed silica products. Amorphous silica hydrates used for industrial products, include opal (hydrated silica of biogenic or inorganic origin), perlite, pumice and tuffs. In addition, crystalline and amorphous silicate minerals and chemicals, abundant in nature and industrial products, must be distinguished from the polymorphs of crystalline silica.

Jan 1, 1997

By Peter Zhang, Daniel Su, Mark Alexander Van Dyke, Heather Dougherty, Bo Hyun Kim

The National Institute for Occupational Safety and Health (NIOSH) has been evaluating longwall mining-induced strata fractures and their impacts on casing stability of Marcellus shale gas wells located in longwall pillars. To understand the extent of overburden fractures after longwall mining, NIOSH researchers drilled a post-mining corehole into the fractured strata above the Pittsburgh coal seam longwall gob. Knowing the extent of the fracture zone height will help gas operators minimize the hazards of drilling into longwall gobs. The core was retrieved from the surface down to the top of the gob void. Various fractures were encountered varying from 35 to 64°, depending on lithologic type and relative closeness to the gob. The longwall panel dimension was 457-m wide and 3657-m long, in which the total fracture zone height was found to be at 141 m and the hydraulic connected fracture zone at 87.7 m above the top of the Pittsburgh seam. In addition to core drilling through the gob, FLAC3D modeling was also used to simulate the formation of fracture zone and the orientations of longwall-induced fractures. This study provides much-needed evidence on the fracture zone of Pittsburgh seam longwall gobs to help gas operators avoid potential hazards associated with drilling through highly fractured zones in longwall gobs.

Jun 9, 2022

By D. J. Sweet, B. Seymour, T. M. Emery, M. Armatys, J. P. Bourgeois, W. Johnson

The Spokane Mining Research Division (SMRD) of the National Institute for Occupational Safety and Health (NIOSH) has partnered with a narrow vein, hard rock underground mine to research the effects of the binder content on the elasticity and post-peak ductility of cemented hydraulic backfill (CHB). This is part of a larger study to enhance the long-term integrity of ground support in underground mines. As mining advances deeper and stresses increase, CHB mix designs will benefit if they can be modified to handle higher levels of strain which are induced by an increased stope closure, typically affected by a reduction in stope width and increased mining depth, or through dynamic loading resulting from a local seismic event. This portion of the research examined the impact of reductions in binder and their impact on Young’s modulus, peak strength, and post-peak ductility.

Mar 2, 2022

By P. Eger

In 1991, LTV Steel Mining Company decided to close an open pit taconite mine in northeastern Minnesota, using a passive treatment approach consisting of limiting infiltration into the stockpiles and wetland treatment to remove metals. Over 50 million metric tons of sulfide-containing waste had been stockpiled adjacent to the mine during its 30 years of operation. Drainage from the stockpiles contained elevated levels of copper, nickel, cobalt and zinc. Nickel is the major trace metal in the drainages, and prior to closure annual median concentrations ranged from 1.5-50 mg/L. Copper, cobalt and zinc are also present but are generally less than 5% of the nickel values. Median pH ranges from 5.0 to 7.5, but most of the stockpile drainages have pH greater than 6.5. Based on the chemical composition of each stockpile, a cover material was selected. The higher the potential a stockpile had to produce acid drainage, the lower the permeability of the capping material required. Covers ranged from overburden soil removed at the mine to a flexible plastic liner. Predictions of the reduction in infiltration ranged from 40% for the native soil to over 90% for the plastic liner. Five constructed wetlands have been installed since 1992, and have removed 60-90% of the nickel in the drainages. Total capital costs for all the infiltration reduction and wetlands exceeded $6.5 million, but maintenance costs are less than 1 % of those for an active treatment plant. Since mine drainage problems can continue for over a hundred years, the lower annual operating costs should pay for the construction of the wetland treatment systems within seven years.

Jan 1, 1999

By Taeyong Lee, Cole Bales, Matt Fowler, John Horne

Mitchell Point Tunnel near Hood River, Oregon is one of the more unique segments of the Historic Columbia River Highway and State Trail being constructed through the Columbia River Gorge. This 650-foot bike/pedestrian tunnel set to open in 2024 is being delivered by FHWA in partnership with Oregon DOT, Oregon State Parks, and the U.S. Forest Service. Primarily driven using drill & blast excavation methods through basalt, the shotcrete and dowel-supported tunnel features masonry portals and ve window adits that provide illumination and views of the river similar to the original highway tunnel of many vistas built in 1915 that was removed in 1966 to make way for Interstate 84. This paper summarizes the planning, design, and construction.

Jun 23, 2024

By D. Nebbia, R. Aliberti, F. Solesin

The launch of a Tunnel Boring Machine (TBM) is one of the most challenging activity parts of the construction of a tunnel. Challenges are coming from limited space available, learning curve, concurrence of other activities and in some cases from the geological conditions. Launching a TBM is an extraordinary and complicated operation requiring a great level of planning. The Earth Pressure Balance (EPB) TBM named “Chris” was successfully launched for the Northeast Boundary Tunnel, the largest component of the Clean Rivers Project in Washington, DC. Due to space and time constraints, the 8-meter diameter TBM was launched from a single 20-meter diameter shaft, with a 30-meter-long tail tunnel by means of umbilical connections. This paper presents the steps followed during the TBM assembly and launching to complete the excavation of the initial drive of the tunnel maintaining high level of efficiency and quality despite the space constraints. Specifically, it focuses on the methods and phases used to extract the excavated material (muck) from the TBM and from the tunnel, to supply consumables, precast rings and backfill grout. The paper presents results in terms of productivity, lesson learned and possible alternatives to be considered in similar conditions.

Jun 13, 2021

By R. P. King

The MODSIM mineral processing plant simulator is used to find optimal combinations of target separation specific gravities in a typical modem coal washing plant. A plant that is set up with these optimal targets can deliver up to 10% more yield at the same ash content as the same plant set up with separation targets chosen by conventional methods. MODSIM is the only simulator currently available that can simulate the liberation of pyrite and other mineral matter during open-and closed-circuit grinding operations. The simulator can therefore be used to assess the benefits of grinding operations in the flowsheet.

Jan 1, 1997

By Henning R. Norbom

Lime has been produced for many centuries. The simple pot kiln was one of the first devices used in this process. It was constructed of stone often on the side of a hill to reduce construction efforts and provide easy access to the top for feeding of limestone. It was fired from below with wood and coal. The pot kiln was very small and operated on the batch principle. The kiln being cooled between each batch, the fuel consumption was horrendous. The lime quality was poor with perhaps only one half of a batch being lime of suitable quality. Of the remaining half one part would be over burned and another part underburned. For centuries the lime burning technique was improved at a barely recognizable rate. One of the first major steps forward was the introduction of the continuous process vertical lime kiln. Although at first crudely constructed, the kiln had a refractory lining. It was charged with alternate layers of limestone and solid fuel usually in the form of coke. Continuous mode of operation, larger unit size and better heat distribution resulted in greatly improved fuel economy. However, quality of lime produced still left much to be desired. One problem was contamination by ashes from solid fuel.

Jan 1, 1978

By Wei Li

Carbothermic reduction kinetics of ilmenite concentrates catalyzed by sodium chloride and the microwaveabsorbing characteristics of the resulting reductive products were investigated; the reduction degree of the reaction was deduced to be . Results show that the activation energy is 112.03 kJ/ mol when NaCl is used as catalyst, lowering to 23.11 kJ/mol for the final stage activation energy using sodium silicate as a catalyst. There is a sharp change in the reduction rate constant at temperature ranges of 1,223 K - 1,273 K and 1,373 K - 1,423 K. Microwave-absorbing characteristics of reductive products were measured by the method of microwave cavity perturbation. It was found that microwave-absorbing characteristics of reductive products obtained at temperatures of 850° C, 1,100° C and 1,150° C show sharp changes. Through X-ray diffraction (XRD) characterization, it was found that the formation of Fe occurs at a temperature of 900° C during the reduction process of ilmenite concentrate. The decrease of FeTiO3 content results in the decrease of microwave-absorbing characteristics, while the increase of Fe content gives rise to the increase of microwaveabsorbing characteristics. The decreasing trend is larger than the increasing trend, which is the main reason for the sharp changes in the microwave-absorbing characteristics of reductive products at the temperature range of 850° C to 900° C. When the decreasing trend is smaller than the increasing trend, it becomes the main reason for the sharp changes in microwave-absorbing characteristics of reductive products at the temperature range of 1,100° C to 1,150° C. Kinetics results show that sodium chloride can catalyze the carbothermic reduction of ilmenite, and microwave-absorbing characteristic investigations indicate that microwave heating can be used in the carbothermic reduction of ilmenite.

By N. W. Johnson

Two analysis tools which have been applied to problems in industrial Flotation processses are the application of kinetics and detailed mineralogical or liberation data, both on a size-by-size basis. The paper describes practical examples of the application of kinetics to examination of the entrainment recovery mechanism, the retardation of valuable minerals at the commencement of flotation sections and the resolution of problems related to valuable species with reduced rate constants at the end of sections. Examples of the usefulness of size-by-size liberation data for monthly composite samples of products from a concentrator are also described.

Jan 1, 1985

By Theodore Feldsher, Seung Han Kim, Mourad Attalla, John Roadifer, Chu-Chieh Jay Lin

Lifelines in seismic regions of the world seldom can escape crossing active faults. Cities in California have been mitigating this risk by constructing improved fault crossings. This paper discusses the analyses and design of the lining for a tunnel carrying a water conveyance pipeline through a fault that can potentially displace during a major earthquake event. The paper presents expected fault displacement, fault width and orientation respective to the tunnel, characterization of the ground surrounding the tunnel and its interaction with the lining, and performance required of the lining. Several other fault crossings will also be presented and discussed

Dec 1, 2022

By Samuel M. Brock

Problems related to strip and auger coal mining have grown with the development of the industry and the economy. New technology has produced equipment that has made mining by surface methods not only highly productive, but potentially highly destructive of water resources and natural environments. On the other hand, growth of the economy has produced an increased demand for clean water, and created new demands for amenity values that natural environments provide. Thus, opposing forces have created conflicts in resource use. And these conflicts have made surface mining highly controversial. Resolving the controversy will require the solving of complex economic and social problems. The essence of the economic problem created by surface mining is that, in the absence of proper regulation, substantial costs resulting from the process are borne by the public rather than the mine operator.

Jan 1, 1968

By B. J. Arnold

Coal blending inherently means homogenizing a mixture of coals so that, overall, the properties of the blend meet some specifications for maintaining power plant performance and emission requirements. In common practice, however, coal blending is at best coal mixing. If necessary, more sophisticated blending systems can produce a more homogeneous feed by using accurate weighing devices and on-line coal analyzers coupled with sampling systems. Blending can be accomplished at the mine, on stockpiles, and from bins, bunkers, and silos.

Jan 1, 1994

By V. A. Shea-Albin

Sandstone escarpments surrounding western coal-bearing plateaus serve as critical habitat for animal species. Effects of mining subsidence on escarpment stability are not well documented; therefore, regulatory agencies may limit extraction of coal reserves underlying escarpments. Because millions of tons of this coal exist on Federal Lands, associated public revenues from Federal royalties, and valuable coal reserves, risk being lost. The U. S. Bureau of Mines is using numerical modeling techniques to analyze effects of subsidence on escarpment stability. Finite element models that incorporate bedding plane slip, gob formation, and movement along joints simulate escarpment subsidence observed in the field.

Jan 1, 1994

By A. Arik

Reliable ore reserve estimates for deposits with highly skewed grade disributions are difficult tasks to perform. Although some recent geostatistical techniques are available to handle problems with these estimations, ordinary kriging or conventional interpolation methods are still widely used to estimate the ore reserves for such deposits. The estimation results can be very sensitive to the search parameters used during the interpolation of grades with these methods. This paper compares the ore reserve estimates from ordinary kriging using several cases in which certain search parameters are varied. The comparisons are extended to different mineralizations to show the changing effects of these parameters.

Jan 1, 1990

By Jürg Künzle

Underground construction is a matter of dealing with the inherent uncertainty of subsurface geology. If the encountered conditions are less favorable than the expected ones, the execution of excavation, support, ground treatment or lining works is likely to require more or different efforts than anticipated, thereby delaying the works and increasing the costs. The 2019 first edition of the FIDIC Emerald Book model contract (FEB) addresses many of the issues to which underground works give rise, including those related to differing site conditions (DSC). This paper examines how under the FEB disputes arising from or in connection with DSC could or should be avoided.

Jun 13, 2021

By W. P. Barnett

In 1988, the U.S. Department of Energy's Pittsburgh Energy Technology Center identified three coal cleaning options for achieving flexible environmental control strategies aimed at reducing energy-related SO2 emissions. These are selective agglomeration, advanced froth flotation, and advanced cycloning. Each technology relies on maximum liberation of pyrite and other mineral matter through feed coal comminution to fine and ultrafine sizes. Research projects designed to expeditiously develop each of these technologies to the point of commercial viability were initiated. This paper will present the status of these projects and the application potential of each technology to coal beneficiation.

Jan 1, 1992

By ANGELA NAIR AVELAR, Reiner Neumann, PAULO R. G. BRANDÃO

The understanding of the influence of the different types of apatite on the performance of mineral processing of igneous phosphate ores is still a challenge due to the difficulty to explain why some types of apatite floats in the froth flotation cell and others do not under the same conditions. Three types of apatite were identified by means of cathodoluminescence (CL) images in flotation concentrate and tailing samples from the Catalão mine: predominantly blue apatite, followed by green apatite and less frequently yellow apatite. The chemical composition of these types of apatite was determined by electron microprobe analysis (EPMA) and LA-ICP-MS. Blue and green apatite respond well to the process, thus remaining in the concentrate, while yellow apatite remained in the tailings. Yellow apatite is the one bearing the lowest P2O5 content and the largest anionic and cationic sites substitution, followed by green apatite, whereas blue apatite is the most homogeneous, with highest P and Ca grades and lowest substitution level. A negative correlation of the amount of phosphorus with fluorine was observed. Furthermore, impregnation of iron oxide-hydroxides in the yellow apatite was also observed. Therefore, the low flotation behaviour is due to low crystallinity coupled with impregnation onto its surface.

Jan 31, 2022