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By Maryam Motamed, Jeremy Stone, Leigh Anne Zhang

Controlling and predicting ground movements are essential to the design of shoring systems. The Courthouse Commons tunnel in San Diego, California, included a 56-foot-deep temporary shaft as a launching point for tunneling using the Sequential Excavation Method (SEM). The rectangular shaft was unique in that it was surcharged on one wall by an 11-story building and employed a hybrid support of excavation design. An array of geotechnical instrumentation was used to monitor lateral and vertical movements at the ground surface. This paper compares the measured ground movement with the predicted ground movement from various excavation stages

Dec 1, 2022

By Yucheng Li, De Huang, Yonghong Liu

Mine frictional resistance is one of the essential parameters of mine ventilation systems, and it is of considerable significance for the prevention and control of mine risks and accident hazards. Frictional resistance requires a lot of resources and time and has errors. To reduce the errors of frictional resistance, a regression model of frictional resistance is proposed based on the correlation analysis of the affecting factors. Through the comparative test analysis of seven regression methods, it is found that the classification and regression tree method for solving the proposed regression model has better performance than other methods. The least square error criterion is used to calculate and rank the importance of the factors affecting frictional resistance. The results show that the cross-sectional area of the tunnel, the support method, and the presence or absence of devices or pedestrian ladders have the most considerable influence on the prediction accuracy of frictional resistance. The support methods and cross-sectional areas are essential input variables. Through the combination test analysis of the influencing factors, the results show that the regression model does not have predictive ability when the number of input variables is less than 3 and the best predictive performance cannot be obtained using all the influencing factors. The best prediction model of resistance is to combine the shape of the tunnel, the support method, the presence or absence of devices or pedestrian ladders, and the cross-sectional area. The method proposed in this paper does not require a lot of resources and time investment, and the frictional resistance error is small. At the same time, it solves the problem of resistance prediction with incomplete data of influencing factors and provides a compelling new method for obtaining frictional resistance parameters.

Jan 28, 2022

By P. A. Plunkert

Metallurgical-grade bauxite was imported into the United States from 11 countries in 2004. The principal suppliers of this 10 Mt (11 million st) of imported ore were Jamaica (33 percent), Brazil (25 percent), Guinea(23 percent) and Guyana (11 percent). The average value of imports, cost, insurance and freight (c.i.f.) U.S. ports, was $31/t ($28/st). Calcined refractory-grade bauxite imports were 165kt (182,000 st) with an average value of $146/t ($132/st), c.i.f. U.S. ports. China supplied 70 percent; Guyana, 22

Jan 1, 2005

By Phil Jones

"Dilution — planned and unplanned – remains a significant cost impairment in the mining process. A series of trials were held over a sixmonth period in fiscal year 2018 (FY18) that established the cost-benefit of new technology as it applies to the alignment accuracy of production drilling rigs in underground mining, thus confirming its ability to limit drilling as one of the causes of dilution. The trials identified three underlying factors affecting drilling accuracy, measurable by blast-hole deviation surveys of planned versus actual toe data. These were rig alignment error, collar location change/ error and in-hole deviation.The trials involved a comparison of existing rig setup processes and technology, with the new technology (Minnovare’s Production Optimizer system). The trials were undertaken in the same environment: the Cracow gold mine, an operating underground mine. The comparison first revealed the extent to which rig alignment impacts blast-hole deviation. Secondly, the new technology was proven to limit rig alignment error, thereby reducing average blast-hole deviation and increasing the number of holes drilled within tolerance by 160 percent.The increased accuracy reduced stope dilution by reducing over-break of subgrade ore. The new technology was implemented at Cracow during the latter half of 2018. Despite utilizing the new technology for just six months of the year, the mine recorded a 5 percent overall reduction in dilution for the full year compared to the previous year (FY17); from 22 percent down to 17 percent (a net decrease of 22.7 percent). Mine management attribute a significant proportion of this reduction to the new technology, along with sequencing and planning improvements. This opinion is backed by detailed stope reconciliation data taken during the trial from 28 stopes — representing 20 percent of the total tonnes mined during FY18. The data identified that stopes drilled using the new technology recorded 62.6 percent less average dilution."

May 1, 2019

By Matthew S. Sanchez, Richard J. Lee, Matthew D. Zock, Drew R. Van Orden

"Current Environmental Protection Agency (EPA) risk models and asbestos fiber counting techniques for monitoring airborne exposures treat all fibers as being equivalent and ignore the effect of dimension on toxicity. While this may have been appropriate when modern analytical methods were not available, the measurement world is now fully capable of making the appropriate distinctions. The importance of width as a determinant of carcinogenicity has been recognized for nearly 30 years within the published literature. Stanton,1 in a landmark study of a suite of fibrous materials, found that durable mineral fibers with widths less than 0.25 mm and lengths longer than 8 mm were causally associated with the induction of tumors. Pott,2 in a later study, postulated a fiber toxicity model that agreed reasonably well with the Stanton findings, but extended the concept to include varying toxicity as a function of length and width. Wylie et al.3 reanalyzed samples used by Davis et al.4 and found that tumor generation was strongly and inversely correlated with fiber width. Crump5 testified increasing fiber length was correlated with disease occurrence. Lippman6 reviewed a number of studies and suggested that mesothelioma was closely associated with long, thin fibers. Berman et al.7 published a risk model, which found that disease was correlated almost exclusively with fibers longer than 40 mm and width less than 0.25 mm. Recently, Loomis et al.8 reanalyzed textile mill samples and found that aspect ratios greater than 40:1 were highly correlated with disease. Incorporation of width into risk models has been limited by the availability of data from operating asbestos plants and, in particular, the observation of an asbestos plant for which there is no observable mesothelioma. There have been only limited studies published on the dimensions of asbestos fibers, with a few serving as the primary references in other literature.9_13 A rare opportunity to collect detailed concentration and dimensional data of airborne crocidolite from an operating asbestos-cement plant using modern analytical procedures arose, providing a chance to supplement the existing literature on airborne fiber dimensions. The asbestos-cement plant is located in the eastern end of Cochabamba, Bolivia along Highway 4. Cochabamba is a relatively large city located in the Andes Mountains, approximately 250 km southeast of the capital La Paz. The city sits in a valley that runs east-west with mountains to the north and south. The crocidolite used in the products made at this facility is mined in central Bolivia, approximately 75 km northwest of Santa Cruz. The crocidolite is a fibrous magnesioriebeckite 14 (blue asbestos). Crocidolite fibers from Bolivia were the subject of prior reports suggesting the fibers are generally longer and thicker than crocidolite from Australia or South Africa.9 At the cement plant, the run-of-mine crocidolite was first pulverized using a hammer mill and then sieved on vibratory sieves to produce fibers of limited size ranges for use in the cement. The sieved crocidolite is mixed with other components, including recycled cement product, to produce a slurry that is vacuum filtered into sheet form. The sheets are then manually molded into a corrugated shape, air dried, and sawed (using circular saws) to accepted dimensions. The sawed sheets are cured in soaking pits for 28 days before being shipped to the consumer. Prior to shipping, the sheets are finished by a light hand sanding followed (at customer request) by applying one or more coats of paint. A detailed description of the cement plant and the industrial hygiene results can be found in Van Orden et al.15"

Jan 1, 2012

By S. S. M. Chan

The design of most underground support systems has largely been based upon empirical rules. This design method has proven to be satisfactory in most cases as witnessed by the number of successfully completed works. However, the adequacy of this approach to the developing technology of ground support systems associated with deep excavation has not been substantiated. In cases where the material has definite time-dependent behavior parameters, rules of past experience become extremely vague and conservative. The Spokane Mining Research Center is currently engaged in extensive research to develop rational design methods for underground structures which will account for the many interacting factors such as in-situ properties of the rock mass, excavation methods, proposed types of support system, construction sequence, and environmental variables. The information presented in this paper pertains to only a segment of the research program,

Jan 1, 1971

By N. S. Kim

Silver paste including nano sized particles maintains conductivity in high temperatures without forming oxide layers. In the industry, printing process produces wasted silver paste inside the cylinder and on silk-screen. Pyrometallugical silver recycling methods have environmental problems and do not extract pure silver after removing polymer and organic materials during the extraction process. In this study a simple wet process, of recycling the waste silver paste, using ammonia, was conducted. Silver ion extraction yield was increased using oxidant in the ammonia solution. Possible extraction yields, such as pH, concentration, temperature of ammonia, oxidant concentration and the extraction time. The particles that were obtained after the extraction process will be used as porous hydrophobic catalytic and applied to AI mask and hydrophobic ink. Keywords: Waste silver paste; Ammonia; Hydrophobic porous support

Jan 1, 2009

By P. Mills

The four top barite-producing countries in the world are China, India, Morocco and the United States. China is currently the largest exporter of barite followed by India. More than 95 percent of the barite mined today is used by the petroleum industry as driller’s mud. The rest is used in the industrial market and the medical field. Most of the barite mined in the United States is in Nevada. This year, mining activity has increased due to an increase in oil exploration/development. This was caused by an increase in the crude oil prices.

Jan 1, 2005

By Jupneek Singh, Zachary A. Kiehl, Leila Safazadeh, Gareth Kennedy, Eleonora Widzyk-Capehart, Jeremy W. Ward

Mine workers are continuously exposed to a host of nonfatal stressors and potentially fatal hazards: noise exposure, excessive vibration, poor air quality, toxicant exposure, ignition of combustible gases, equipment-related accidents, and thermal heat stress. Wearable or portable sensors and contextual analytics provide a platform to unobtrusively collect and fuse multimodal health and safety data in real time to compute both acute safety and longitudinal health insights. This paper presents preliminary trial results, conducted by Simtars, VigiLife, Inc., and Queensland Mines Rescue Service, of the application of wearable sensors to monitor heat stress and other vital biometrics for mines rescue personnel.

Feb 1, 2024

By J. G. Pippenger

Rio Tinto Coal Australia (RTCA) developed the Meandu Mine in Queensland, Australia in 1983 to supply thermal coal to the adjacent and newly constructed Tarong Power Station (TPS). In designing the mine, RTCA selected Meandu?s best economic reserves for a 27-year life based on station owner Tarong Energy Corp.?s (TECs) estimated life for TPS. That 27-year plan changed dramatically in the early 2000s when TEC approved life extensions to TPS?s four existing units plus construction of a fifth unit. After reviewing Meandu?s remaining reserves, RTCA decided the nearby Kunioon reserve offered the more economic option for maintaining deliveries beyond 2010. Those plans changed again in 2007 when TEC chose to purchase the Meandu Mine and nearby reserves. TEC then selected Thiess Pty Ltd. (Thiess) to continue operating Meandu until the new mine at Kunioon could be developed. After assuming operation of the mine in 2008, Thiess began a review of Meandu?s remaining reserves and found considerable coal available with economic potential. Working jointly with TEC, Thiess performed several analyses on Meandu and subsequently the Kunioon coal reserves. The results changed TEC?s decision from expediting Kunioon?s construction to instead continuing Meandu?s operation for up to 15 additional years.

Jan 1, 2011

By Frank F. Rahne

Butler Taconite, operated by the Hanna Mining Company, is an Iron ore pelletizing operation that is located on the Western end of the Mesabi Iron Range in Northeastern Minnesota. The operation mines low-grade taconite ore and through primary crushing, two stage grinding, magnetic separation, agglomerating and indurating, produces 2.6 million annual tons of high quality, 66% iron pellets. Mining and stripping is done with 13 - M100 trucks and 5 - 12 cu. yd. shovels. The operating processes in the concentrator and pellet plant are primarily con¬trolled through a centralized control room and monitored by a PDP l140 computer. During 1969 and 1970, a re-organization of the Company took place. Through this re-organization, each mine unit was analyzed and studied to determine the proper staffing of the internal departments. At this time, it was decided to continue with further detailed studies of the Maintenance Department with the intent to reduce maintenance costs. Maintenance costs at the time of the re-organization were 38.6% of the total mine operating cost. The preliminary study indicated that the Maintenance Department had a system of maintenance, as a matter of fact, it had a separate system in each sub-maintenance division and in some of the sub-divisions each foreman had a system of his own. Therefore, from the data collected, it was decided to develop one system of maintenance that could be utilized throughout the entire operation. To determine the type of system suitable to all phases of the operation, detailed time and method studies were conducted. All types of maintenance tasks performed at the operation were studied. The data collected was analyzed and the recommended improved methods were reviewed with the Maintenance Superintendent and his staff. The new improved methods that were accepted as feasible, were introduced into the system immediately.

Jan 1, 1975

By R. L. Grayson

Based on the relationships between severity measure vs. productivity and other factors, this paper presents a comprehensive analysis of US underground coal mine injuries in 1996 by mine size. From the 1996 data, it was concluded that, generally, the larger the mine, the more productive it is (in tons per employee-hour) but the more severe is its injury experience (r = 0.65). However, within very large, large and medium mines, the more productive the mine, the less severe is its injury experience (r = -0.43, - 0.36 and -0.26, respectively). For small and very small mines, a deeply nested analysis would be required to understand relationships. Other interesting relationships and comparisons are presented.

Jan 1, 2002

By SAHENDRA SINGH, SANJIT KUMAR PAL, DHARMITA HORO

The North Singhbhum Mobile Belt (NSMB) lies between two crustal-scale shear zones, the South Purulia Shear Zone (SPSZ) at the north, and the Singhbhum Shear Zone (SSZ) at the south. The Babaikundi-Birgaon Axis (BBA) is an east-west trending secondary shear zone in the NSMB lying south of SPSZ, which is known for the occurrence of gold along with other sulfide minerals within the quartz reefs. The present study has been carried out at north of Ichadih village, which lies on the BBA. The present study attempts combined electrical resistivity tomography (ERT) and self-potential methods along a profile of 470-m length in the Ichadih area to map the potential mineralized zones. Initially, ERT sections generated by Wenner, Wenner- Schlumberger, dipole-dipole, and joint inversion of the combined array have been analyzed, and results are validated through the analysis of model resolution. A prominent low resistivity (10–100 Ωm) associated with quartz reef/limonitic quartz reef at a depth of approximately 30–85 m, encircled by a high resistive (more than 10,000 Ωm) formation associated with metasedimentary rock, has been delineated using joint inversion of the combined array. Further, analysis of self-potential (SP) anomaly using particle swarm optimization inversion also confirms the prominent low SP anomaly at a depth of 77.3 m, which is analogous to the low resistivity anomaly identified in the joint inversion of the combined geo-electric array. Subsequent analysis of a complex synthetic geo-electrical model analogous to the present field situation proves the efficacy of the joint inversion of combined arrays. As a whole, joint inversion of multi-array data is established as an efficient technique for better subsurface imaging in case of the complex subsurface structure. In-depth analyses confirm the possibility of sulfide mineral-rich deposit (quartz reef/limonitic quartz reef) which requires further geological drilling and lithogeochemical sample analysis, for possible future exploration.

Oct 26, 2020

By Jacob Mathis, Mark Bradford, Alston Noronha, R. M. True

In June 2022, Louisville MSD completed a 6.5-km (4.0-mi), 6.1-m (20-ft.) diameter CSO conveyance and storage tunnel system located along the Ohio River in downtown Louisville, Kentucky. For large diameter shaft and tunnel construction, drill-and-blast operations among other methodologies were used in close proximity to federal, commercial, and residential properties with no impact to stakeholder infrastructure. s one of the rst maor tunneling proects in Louisvilles metropolitan area, this paper explores Black & Veatchs rigorous geotechnical instrumentation monitoring program that provided uality assurance for local stakeholders and afrmed innovative tunneling solutions can be successfully executed in an urban setting.

Jun 23, 2024

Fluorspar was not mined in the United States during 2004, although a small amount of usable synthetic fluorspar (CaF2) was produced from industrial waste streams. The majority of fluorspar consumed in the United States came from imports or stockpiled material purchased from the National Defense Stockpile (NDS). In addition, consumption is supplemented by use of by-product fluorosilicic acid produced at phosphoric acid plants. In 2004, annual production of fluorosilicic acid was 50kt (55,000 st) or about 88 kt (97,000 st) of 92 percent fluorspar equivalent. In 2004, annual production of fluorosilicic acid was 50kt (55,000 st) or about 88 kt (97,000 st) of 92 percent fluorspar equivalent.

Jan 1, 2005

By C. Y. Kao, Roger Y. Cheng, C. S. Hsieh

The mushroom-shaped Minghu power cavern located in central Taiwan is 21.2 m (W) by 40.5 m (H) by 127.2 m (L) and is designed to house 4 units of power generating-pumping equipment with a total capacity of 1,000 MW. This paper presents an introduction to the geological conditions at the cavern site; the rock mechanical tests undertaken; the design approach adopted; the construction method and sequence followed; and the instrumentation provided in the roof arch to monitor the behavior of the surrounding rocks. The measured data collected from the embedded instruments will be compared with those obtained from theoretical analyses and presented in this paper. Several technical problems encountered during the construction stage are covered and the solutions of these problems are also described therein.

Jan 1, 1983

By E. Tarshizi

Research was conducted to develop a simulation and animation model for an aggregate (sand and gravel) mine operation. This model can assist the mine engineers to investigate and consider the various options of haulage systems which are critical for the mine operation productivity. Discrete-event system simulation studies can be used for the typical haulage issues that mining engineers are often faced with: using truck fleet haulage, conveyor belts, or a combination of both. The simulation has identified some strengths and weaknesses in the current loading and hauling fleet of the mine, and has resulted in some suggestions for improving the system. The simulation includes animation of the operation. Animation is needed to enhance the benefit of any mine simulation model. By combining the visual power of animation with a mine simulation, a complete picture of the mine system is obtained and displayed. The mine is modeled and animated using GPSS/H® and PROOF Professional®, both of which have shown great applicability in discrete mining simulation projects.

Feb 23, 2014

By Jr. Wallace

This paper describes the importance of mine ventilation and air conditioning in the operation of a nuclear waste repository. It discusses the impact of ventilation on determining the number and size of shafts and access drifts to and within a repository horizon. The paper also describes the need to maintain separate ventilation systems for waste emplacement and construction operations. The requirement to have filtration capabilities for exhaust air from waste emplacement areas is discussed. Because radioactive high level waste will induce high temperatures in the emplacement drifts, the ability to cool an emplacement drift for re-entry requirements is important. The paper discusses strategies to cool an emplacement drift and the possibility of using continuous airflow to control temperatures in these drifts.

Jan 1, 1991

By Erika Moonin, Jim Nickerson, Marcus Jensen

"This paper will explain how the Contractor and Owner avoided a contractual dispute involving characterization, impacts, and final remedy for challenging ground conditions encountered during drill and blast excavation of the starter tunnel required for launch of the tunnel boring machine (TBM). During excavation more than 600 feet underground, the Contractor encountered a large complex fault zone subject to more than 14 bar of water pressure. Successive ground inflows from the fault complex over a six-month period presented significant technical and partnership challenges for the team and ultimately delayed the project by nearly one year. This paper will discuss how the Contractor, Owner, and their respective consultants worked together to address these challenges, make decisions, and ultimately move the project to successful completion. PROJECT BACKGROUND AND NEED Seven states of the western United States of America rely heavily on the Colorado River and its tributaries for their water supply. The primary source of water for the Colorado River is winter snow that falls in the mountains ringing the Colorado River basin, including the Rocky Mountains, the Wind River Mountains, and the Uinta Mountains. Flows in the Colorado River vary significantly from year to year, depending on the amount of snow and rain deposited in the basin. During the 1980s and 1990s, snowfall was relatively abundant and Colorado River flows were high on average. Beginning in the year 2000 and continuing to the present day, snowfall has been well below documented historical averages and Colorado River flows have diminished. In fact, a trend toward diminishing flows is evident during the period of the historical record. This variability in Colorado River flows and the trend to lower flows is represented in the following Figure 1."

Jan 1, 2016

By J. J. Snodgrass

Faults, sandstone channels, and abandoned mine workings present severe safety hazards, disrupt mining, and necessitate costly precautions or discontinuance of operations. In addition to fault detection, mining companies have a need to map discontinuities such as seam thinning and previously mined areas in both longwall and room-and-pillar operations. Initial field tests demonstrated successful generation and propagation of higher order guided wave modes. Theoretical studies indicate potential for improved resolution by sensing small details in the coal seam and roof structure. Controlled-waveform source transducers and specialized detectors are particularly useful to preferentially excite and detect the Love (SH) and Rayleigh-type (P-SV) waves, including the higher frequency modes. The distinct observation of reflections using the transducers in the shear wave mode makes feasible the detection of the water-filled voids.

Jan 4, 1985