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By J. Peterson, R. Michael, D. Yantek, E. Ferro

Among underground coal miners, hearing loss remains one of the most common occupational illnesses. To address this problem, the U.S. National Institute for Occupational Safety and Health Office of Mine Safety and Health Research (NIOSH OMSHR) conducts research to reduce the noise emission of underground coal mining equipment, an example of which is the roof bolting machine. Field studies show that, on average, drilling noise is the loudest noise that roof bolting machine operators would be exposed to, and it contributes significantly to the operators’ noise exposure. OMSHR has determined that the drill steel and chuck radiate a significant amount of noise during drilling. OMSHR and the Corry Rubber Corporation (CRC) have developed a bit isolator that breaks the steel-to-steel link between the drill bit and drill steel and a chuck isolator that breaks the mechanical connection between the drill steel and the chuck. This effectively reduces the noise radiated by the drill steel and chuck and in turn reduces the noise exposure of roof bolter operators. This paper documents the evolution of the bit isolator and chuck isolator. Laboratory testing confirms that production bit and chuck isolators reduce the A-weighted sound level generated during drilling by 3.7 to 6.6 dB.

Jan 1, 2011

By D. U. Gustafsson

After half a million meters drilled with Wassara we are now confident that ITH hammers powered with simple water will become an established product for production drilling. Today four drill rigs in LKAB Malmberget equipped with Wassara drill about 25 000 m per month of 4 1/2" holes. In Kidd Creek, Canada, Was sara is used for production drilling in stopes with good results. The first Wassara 6" hammer has drilled a 36 meter long, completely straight horizontal cut hole for drifting in the LKAB Malmberget Mine. Main advantages are about doubled penetration rate, very good air quality and improved hole cleaning which facilitates stabilized drilling. Disadvantages are resistance to new technology and, in some cases, the increased use of water.

Jan 1, 1995

By P. K. Naik, S. C. Das

Leaching studies of low-grade manganese ore containing 31.77% Mn and 23.71 % Fe from Nishikhal, India, were carried out using pyritiferous lignite as a reductant in sulfuric acid medium. The variables studied were quantity of lignite, sulfuric acid concentration and temperature. Regression equations for the extraction of manganese and potassium were determined from 23 full factorial design data. The experimental conditions for the extraction of manganese were optimized using the steepest-ascent method. It was found that 99.03% of the manganese could be extracted in three hours with an ore to lignite ratio of 1:1.8, a sulfuric acid concentration of 1.9 M and a temperature of 99°C. Key words: Leaching, Manganese ore, Lignite, Statistical design

Jan 1, 2003

By Sergio Estebanez, Martha Gross, Ruben Rubal, Yvonnick Rescamps, Alexandre Cochennec

The Hampton Roads Bridge-Tunnel (HRBT) Expansion project in coastal Virginia, USA will add two 1.5-mile (2.4 km) TBM bored tunnels alongside two existing immersed-tube tunnels between artificial islands. The site’s unusual constraints and the requirements of a large-diameter variable-density TBM shaped the design-builder’s decisions for handling TBM inputs and outputs, siting the TBM plant and supporting equipment, and sequencing tunnel-construction operations. This paper addresses the logistics necessary to enable key functions of the 46-ft (14-m) TBM and its ancillary equipment, including transport of most materials by barge, U-turn of the TBM on an artificial island, and delivery of materials for the second tunnel through the first one while interior structures are under construction.

Jun 13, 2021

By M. D. Dennis

Precious metal mineralization at Mt. Hamilton" Nevada is associated with a poly-metallic, garnet-pyroxene skarn system developed in middle to upper Cambrian calcareous shales, limestones and dolomites. The skarn is developed around the Cretaceous Seligman and Monte cristo calc-alkaline stocks. Gold is associated with intense retrograde alteration. Later epithermal quartz veins containing gold, silver, base-metal sulfides, and sulfosalts cross-cut skarn alteration. Westmont Mining Inc. is currently developing two mineralized zones containing a geologic resource of approximately 7.7 M.T., which averages 0.05 OPT gold and 0.5 OPT silver. The project will have an estimated mine life of seven years, with a planned annual production rate of 35,000 ounces of gold and 300,000 ounces of silver.

Jan 1, 1989

By George Munro

Heavy water inflows of up to 1350 1/sec in the 19.6 km Moawhango-Tongariro Tunnel section of the Tongariro Power Development Scheme in New Zealand gave rise to severe operating problems, particularly in the equipment stripping stage when pumping installations had to be removed. Due to the necessity to commence stripping from the upstream side the contractors. Codelfa-Cogefar (NZ) Limited, took the decision to install a steel bulkhead some 5000m in from the lower. Tongariro, portal. The article lists the considerations taken in the placement of the bulkhead, and gives details of its design, installation and final removal. A brief description of the geology of the tunnel. together with water flow sources, rates and pressures is also included.

Jan 1, 1981

By Y. Pan, P. Tukkaraja, R. BHARGAVA, V.V.S. VYTLA, S.J. SRIDHARAN

Panel caving is an underground bulk mining method that uses gravitational force to mine massive, steeply dipping and deep-seated ore deposits at lower operating cost. To control dust and gas emissions entering the production level during the extraction of ore from the draw points in a panel cave, relatively negative pressure is created in the cave by installing an exhaust fan in the exhaust drift located on top of the cave. As caving is a dynamic process, designing an effective ventilation system is challenging; therefore, estimating the airflow resistance offered by the broken rock inside the cave is critical. This study investigates the effect of changes in the bulk porosity of the broken rock on the cave airflow resistance using the computational fluid dynamics (CFD) approach. The results show an inverse relationship between the cave airflow resistance and the bulk cave porosity. The pressure-quantity characteristic curves presented in this paper provide valuable information for sizing and operating an exhaust fan used for a mature panel cave ventilation.

Nov 1, 2022

By STEVEN J. SCHATZEL, Zoheir Khademian, KAYODE M. AJAYI

The integrity of unconventional shale gas well casings positioned in the abutment pillar of a longwall mine could be jeopardized by longwall-induced deformations. Under such scenarios, the surrounding fracture networks could provide pathways for gas flow into the mine, creating safety concerns. To provide recommendations for developing guidelines that ensure a safe coexistence of longwall mining and unconventional shale gas production, this study uses a discrete fracture network (DFN) model to evaluate the impact of parameters that could affect potential shale gas flow into the mine in the event of a casing breach. These parameters are evaluated using a conceptualized DFN realization that is representative of the fractured zone in the overburden, and the range of parameter variations are within values validated with field measurements.

Mar 1, 2023

By AJIT SWAIN, SUNATI MOHANTY

The ability to predict the dewatering performance of an industrial hydrocyclone from a laboratory-model hydrocyclone is of great importance. In this study, laboratory-scale hydrocyclone experiments were conducted using silica sand samples at 10 percent solid concentration for dewatering with Mozley hydrocyclones with diameters of 2 in. and 4 in. The objective is to predict the design parameters for an industrial dewatering cyclone to achieve higher solid concentration in the underflow. A model was developed based on the Nageswararao hydrocyclone model with the help of a commercial simulator for a hydrocyclone operating at 100 t/h and 20 percent solid concentration to achieve 80 percent solid recovery at 45 percent solid concentration in the underflow.

Mar 1, 2023

By W. Burger

For the development of deep hard rock mines fast access to the orebody is critical. In some cases the mineralized area is more than 1500 m (5000 ft) below surface. Excavation of shafts or declines is typically on the critical path of the project schedule. Saving time on those activities can significantly increase the net present value of the mining project. Mechanical excavation methods are a step-change in excavation performance and labor safety compared to drill and blast operations. In hard rock conditions roadheaders can not be used effectively, so disc cutting is the first choice. For excavation of declines tunnel boring machines (TBM) can be used in many cases. These provide in certain rock conditions considerably higher production rates compared to drill and blast excavation.

Jan 1, 2010

By A. Mahtab, S. Xu, P. Grasso, B. J. Fu

The large population base, complex geology of the large land mass, and notable commercial activity have accelerated the development of underground construction market in China. The projected lengths of underground openings per year in the various sectors are: hydro-tunnels, 180 km; coal mine entries, 40 km; transport-tunnels, 300+ km. An example of the mega projects (being planned by the Government) is the water supply scheme for connecting Yangtze river to Yellow river involving 131 km of water tunnels with a diameter of 8-10m. Several large projects are highlighted in the paper with reference to the schemes for generating hydro-power, mining of coal and minerals, and constructing transportation networks. The related problems of construction and geomechanics are outlined.

Jan 1, 1995

By P. W. Erickson

Development of the Twin Buttes mine entailed the largest known preproduction stripping job in the history of mining. It linked earthmovers and conveyor belts in a new approach to development of a pit that may reach, or even exceed, dimensions of 1 x 1-1/2 miles at the surface and go as deep as 1800 feet. The orebody to be stripped was covered by an average of 460 feet of alluvial gravels, which presented an initial stripping job of great magnitude. The initial pit layout and the original time schedule established early in 1965 called for the excavation and disposal of about 250,000,000 tons of alluvial overburden before the end of 1969. Allowing about a year for equipment delivery, this schedule left four years to do the job averaging about 62-1/2 million tons per year. In 1964 when The Anaconda Company undertook the development of Twin Buttes, it was recognized that special planning was necessary for the disposal of waste material and tailings. Environ- mental control was a prime consideration and is particularly sensitive in the Twin Buttes area due to the proximity to residential developments. Disposal of the 250,000,000 tons of alluvium, as well as future rock and tailing waste material, presented a problem which Anaconda engineers resolved by designing a plan to spread out much of the alluvium over an extended area, including a massive 11- 1/2 mile dike system which will impound mill tailing in three basins. The tailing will be impounded behind these-dikes to avoid wind exposure and blowing. The dikes also serve as a

Jan 1, 1974

By Y. H. Kim

A simulation procedure has been developed that realistically portrays aggregate growth and disintegration for particular types of floc structures in water and wastewater treatment processes. The procedure requires local dissipation rates and specification of an interaction distance between colliding particles. A principal difficulty encountered in polymer flocculation, however, arises from changes in conformation of adsorbed macromolecules. Therefore, in systems where polymer flocculation occurs by bridging, dynamic changes in the particle size distribution depend upon the interaction of nonlinear. stochastic hydrodynamics with particles whose growth results from a number of concurrent and sequential random processes.

Jan 1, 1988

By S. Afrouz, C. Keles, E. Sarver, A. Greth

While respirable dust monitoring has long been done on the basis of mass concentration, it is increasingly recognized that specific dust characteristics may play an important role in health outcomes. Scanning electron microscopy with energydispersive X-ray (SEM-EDX) can be used for detailed particle analysis, but the quality of results can be dependent on the sample substrate; ideally, particles should be deposited on a smooth, uniform substrate like polycarbonate (PC). While direct air sampling onto PC filters is possible, this is not the standard approach in many situations. For example, in coal mines, polyvinyl chloride (PVC) filters are often used. They enable conventional mass-based analysis — of the total respirable dust, and the content of crystalline silica in this fraction — but are fibrous and thus not ideal for SEM-EDX or other microscopy. To address this issue, the current work tested a simple method to recover respirable dust particles from PVC filters and redeposit them to PC. Results generally indicated that recovered particles are representative of the original dust sample in terms of mineralogy distributions. Where this was not the case, the issue appeared to be with high particle loading density during SEM-EDX work rather than related to the recovery/redeposition method itself. This bodes well for applications where a single PVC filter sample could be used for nondestructive analysis to determine respirable dust mass and/or respirable silica mass, followed by preparation for SEM-EDX analysis to evaluate particle characteristics. The recovery and redeposition method might also be adapted for other applications, such as to enable the analysis of respirable dust samples collected by the continuous personal dust monitor (CPDM).

Oct 1, 2024

By Greg Beckstrom

Minnesota is a major mining state. This statement is not a dream or stretch goal but is a fact. As reported in a recent edition of Mining Engineering magazine, Minnesota ranks as the third largest state in terms revenues generated from nonfuels mineral production. The vibrancy of the mining sector in Minnesota can be attributed to several factors. The northeastern corner of the state is home to Minnesota?s iron range, one of North America?s largest deposits of iron ore. Iron ore from Minnesota is a strategic resource that has been [ ] instrumental to the nation?s development ? 90 percent of the iron used to build ships and planes during World War II came from Minnesota. Taconite pellets now produced from openpit mines on the iron range are shipped to steel mills worldwide. The growing appetite for steel in China and India has reignited once moribund mining operations throughout the iron range.

Jan 1, 2012

By Juan Andres Jarufe, Carlos Cifuentes

Numerical modelling has been extensively used to estimate plastic displacement in faults and rock mass surrounding mine excavations. Particularly, for fault slip seismicity, modelled plastic displacement is usually utilized to estimate seismic potential, however these methods assume that all the displacement caused during an specific simulated excavation step, is released as a single event at each step. This representation corresponds to a conservative estimation since rock mass displacement does not occur as one single event but as an exponential distribution of many small displacements and a few large ones. When displacement is expressed as seismic magnitude, this exponential distribution is addressed as the Gutenberg Richter (GR) relationship. This paper present a method to decompose the results from numerical models into a distribution of seismic events The reconstruction of the GR relationship from modelling displacement permits not only a more realistic approximation of the expected maximum magnitudes but also provides a tool to develop a probabilistic estimation of the maximum possible magnitudes.

Apr 26, 2022

By V. de Ruiter

In the northwestern part of the Netherlands lies the deepest solution salt mine in the world. The company operating the mine is Frisia Zout bv (part of the K+S group). Extracting the NaCl from caverns at a depth of nearly 3000 m has a lot of challenges. Continuously monitoring, among others, the flows, pressures and salt concentrations is necessary to safely and economically mine the salt. A system has been set up at Frisia to be able to monitor the data from a distance. Data has been put in graphs to monitor the trends daily. All gauges are also continuously monitored to maintain accuracy. With this system a better understanding of the mining process has been made and has led to many optimizations.

Jan 1, 2008

By MOHAMED WAEL, ANASTASIA GOEVA, ABDULAZIZ TAWFEEQI, IHTISHAM TARIQ, S. M. ZAKIR HOSSAIN, NIAZ ALI KHAN, MUHAMMAD FAISAL IRFAN

Carbon dioxide (CO2) mineral carbonation is a carbon capture and storage (CCS) technique that can sequester CO2 permanently in the form of durable carbonate minerals. Extendable permanent storage capacity — onshore and offshore storage reservoirs — and the exothermic nature of the mineralization process make this technique attractive [1]. In the present study, maximum carbonation efficiency for aqueous mineral carbonation was achieved through two steps: optimization of calcium leaching from cement kiln dust followed by the reaction of pure CO2 with the calcium hydroxide precipitates formed by hydroxylation using sodium hydroxide (NaOH). Optimization of calcium leaching is highly important, as it is a rate-limiting reaction step in mineral carbonation and also influences and enhances the carbonation efficiency. To maximize the calcium leaching as well as carbonation efficiency, response surface methodology — with either Box-Behnken design or central composite design — was applied. It is the most well-known statistical, fully randomized and bias-free method for determining optimized conditions using quadratic regression models.

By MYRIAM FRANCOEUR, JOHN R.R. BOWLING, ADAM MCFADDEN

As duct-fan systems push the envelope of power, length and cost, their design calls for a more comprehensive technoeconomic analysis to ensure they deliver the expected results without failure and cost overrun. This work explores the numerous factors to include in the design of an extensive (semi-)rigid duct-fan system. Besides delivering a given airflow, the system must satisfy component limitations and power constraints during its lifetime. We evaluate the assumptions underlying the positioning of in-line booster fans in a long gapless duct-fan system and propose a strategy for specifying the location and blade pitch of successive booster fans to prevent system failure due to a partial vacuum.

Oct 1, 2022

By T. R. Ellis

"In August 2013, the Appraisal Practices Board of the U.S. Appraisal Foundation issued its “APB Valuation Advisory #4 - Identifying Comparable Properties,” which contains analysis and examples that may suggest a broader meaning of the term “comparable properties” than is current convention in real property value appraisal in the United States and internationally. The advisory is directed at the appraisal of real property of all kinds, including interests in mineral properties, as indicated by the inclusion of two mineral property appraisal papers in the appendix that lists suggestions for further reading.This paper firstly reviews as background the historical meaning of a comparable property, with its perceived constraints, against real-world examples of transacted mineral properties that are adjusted to subject properties to provide market value indications. The advisory’s findings are then examined and evaluated as to whether they may influence and benefit the work of mineral property appraisers, particularly in situations where their sales comparison analyses may be challenged. The conclusion is that the combination of constraints that the advisory’s findings specify for use of the term “comparable” will for mineral properties be met infrequently or rarely. As a result, mineral property appraisers are advised to avoid using the terms comparable or “comp” when referring to transactions of mineral properties that they analyze to derive data for appraising the value of their subject mineral properties. IntroductionA mineral property appraiser rarely finds a sale of a mineral property that meets the literal meaning of the term “comparable sale,” by being directly comparable to the subject property of the appraisal in all factors of significance in the determination of the value of the property interest being appraised. Real estate appraisers have long used a more liberal interpretation of the meaning of comparable sale and its commonly used abbreviation, “comp.” Real estate appraisers compare sales to their subject property on the basis of price per hectare or acre of land and price per square meter or square foot of building floor area. Adjustments totaling to within the range of +30 to -30 percent from the sale property to the subject, before factoring in the property area, have generally been viewed as appropriate for the sale to be considered a comparable sale."

May 1, 2016