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By Ritika Kundu, Moussa Wone, Amanda M. Morgan, Tatiana K. Proctor

The Piney Branch CSO 049 Storage Tunnel (PBST) will be the last major project for the DC Clean Rivers Program. The project includes construction of a 2,200-foot-long, 18-foot-internal-diameter storage tunnel; two connections to combined sewer infrastructure; and two shafts. Major challenges include excavation underneath an existing live outfall that must remain in service; excavation of the tunnel through several areas of low rock cover and mixed-face conditions; and negotiations with a variety of federal, regional, and local stakeholders to address project impacts. This paper describes the overall project scope; geotechnical conditions along the alignment; design and construction challenges; and construction procurement.

Jun 23, 2024

By R. K. Mehta, M. G. Bersch

Characterization of an ore or mill product is routinely performed by time consuming and tedious chemical analyses, sink-float separations, etc. Additionally, these types of tests do not provide data concerning the interrelations and interlocking of the mineral constituents. This paper discusses some of the applications and capabilities of the Minerals and Material Science Research Center at The University of Alabama. Back-scattered electron images of coal, oil shale, complex suldfide, and tantalium ores were acquired using a JEOL 8600 electron microprobe with a NORAN (formerly Tracor Northern] 8500 image analysis system. Methods of analysis and typical results are discussed.

Jan 1, 1992

By Patti J. Best

The Southern Powder River Basin (SPRB) now commands 30% of the US utility, coal market due to the region's low mine production costs, competitive rail rates and low sulfur content. In 1997, production exceeded 240 Mt (265 million st). This was an in¬crease of 104 Mt (115 million st) since 1989 and 4.5 Mt (5 million st) above 1996. Continued growth is expected as the second phase of the Clean Air Act Amendments (CAAA) approaches. This growth will be the greatest in the southern part of the Basin where coal quality is higher. Coal characteristics SPRB coal is classified as subbituminous due to its low heating value and high moisture content. The coal is characterized by low sulfur and ash contents, low ash fusion temperatures and high reactivities. In 1997, the average heating content was 8,593 Btu/lb, with an average sulfur and ash content of 0.79 lbs S02/million [ ] Btu and 5.13%, respectively. The distinguishing characteristic of SPRB coal is its low sulfur content. Most SPRB coal contains less than 1.2 lbs S02/million Btu. This is the approximate definition of "compliance" coal for Phase II of the CA AA. Much of the coal, particularly in the southern part of the Basin, is referred to as "super-compliance" coal due to SO2 contents of between 0.4 and 0.7 lbs SO2/million Btu. The SPRB is divided into three geographic clusters based on coal quality. Mines located in the southern part produce coal with the lowest average sulfur content and highest heating content, almost 400

Jan 1, 1998

By R. V. Ramani, K. V. Raj

"The air flow problems in open pit mines are complex. Computational fluid dynamics (CFD) models provide a detailed knowledge of the airflow pattern and velocity distribution, temperature, and pollutant concentration within an enclosed domain of the open pit. A range of turbulent model can be selected for varying complexity and accuracy. Pollutant transport models, however, differ in their assumptions and structure as well as in the algorithm they use; as a result, prediction varies from model to model. This paper presents a study of pollutant transport in an actual open pit mine under stable boundary layer. The objective is mainly to test two turbulence models using the same input conditions, model constants, and similar geometry. Measured data are used to compare results of the two CFD models, namely, the kappa-epsilon (?-e) model and the Large Eddy Simulation (LES) model. Despite the complex synoptic situations, different meteorological input data and the fast changing conditions, the simulation results from both the models are in good agreement regarding the dispersion of pollutants.INTRODUCTION Modeling of contaminant transport under Arctic air inversion is an important step for an assessment of the amount of pollutants within the open pit. The Airflow in open pit mines is of larger scale and does not follow the principles of pipe flow. The air flow problems in actual open pit mines are thus far more complex. CFD models provide a detailed knowledge of the airflow pattern and air velocity distribution, temperature, and pollutant concentration within an enclosed domain of an open pit. There is no known application of CFD in three-dimensional modeling of air flow in large open pit mines. Two equation RANS kappa-epsilon (?-e) and Large Eddy Simulation (CFD) models, however, have been developed to solve the stable boundary layer (SBL) problems in Atmospheric Sciences (Baklanov 2000, Basu and Porté-Agel 2006, Dop and Axelsen 2007, Bandopadhyay et al. 2014). Because an exact flow situation in open pit mines is not known a-priori, it is therefore, necessary to investigate various turbulent models to identify the appropriate model that would simulate the flow phenomena with reasonable accuracy, and predict the contaminant distributions within the pit. Dispersion models differ in their assumptions and structures as well as in the algorithm they use and, as a result, predictions vary from model to model. Furthermore, it is also important to investigate the behavior of a CFD model in simulating a complex phenomenon such as the transport and distribution of contaminants in open pit mine under Arctic air inversion. The simulation of an enhanced period of turbulence in SBL is of particular interest because traditional air pollution dispersion models cannot explicitly treat such intermittent events, and yet the SBL is often the worst-case scenario in an open pit pollution transport"

Jan 1, 2015

Industry and regulatory agencies have requested guidance on safe blasting near transmission pipelines. The US Bureau of Mines (USBM) and Amax Coal Co. studied surface coal mine overburden blasting near four steel and one PVC pipeline of 15 to 51 cm-diam (6-20 in.-diam), monitoring vibration, strain and pressure. Unlike tests of small blasts simulating construction, these were up to 1 t (2200lbs) per delay in 31-cm (12-in.) blastholes. Worst-case comparisons showed that 12.7 cm/sec (5 in./s) blasting vibrations produced strains about one fourth that of pressurization and 10% to 18% of the ultimate tensile strength. No failures occurred from blasting as close as 15 m (50 ft), which produced vibrations over 60 cm/sec (24 in./s).

Jan 1, 1995

By G. Potts, K. Raiber, T. BoBo

Effective control of balling line circuits is a problem taconite companies have been dealing with for over thirty years. The sensitivity of balling circuits to changes in moisture, bentonite, concentrate particle size, and other operating parameters are the main reasons for control problems. This paper presents test results and describes the integration of existing instrumentation with a digital image analysis system on a balling circuit. This work has the goal of developing control strategies to automatically adjust water spray and bentonite addition, to optimize the size distribution on the roll screen and reduce the variability in control between balling attendants, resulting in more consistent greenball product quality.

Jan 1, 2003

By Robert W. Row

Advanced physical coal cleaning processes that are now under development may remove significantly greater fractions of pyritic sulfur and ash than do commercial coal cleaning processes at comparable heating value recoveries. These processes may be useful for reducing sulfur dioxide emissions from electric utilities and other emission sources. However, little work has been done to determine their applicability to any major coal market. The northeastern states of the United States are interested in burning more coal, but with further sulfur dioxide emission restrictions. Their nearest coal sources are relatively high sulfur Northern Appalachian coals. The project discussed in this paper, which is scheduled to be completed in June 1985, has the objective of technically and economically evaluating various coal supply scenarios involving five selected advanced physical coal cleaning processes; and comparing the economics of them with alternative fuel supply options open to the northeastern users.

Jan 1, 1985

By M. Hardy, K. Nielsen, M. Ramey

American Soda, LLP has commissioned the first solution mine for recovery of naturally formed sodium bicarbonate (nahcolite) from low-grade deposits using high-pressure, high-temperature injection fluid. This project, known as the Yankee Gulch Project, was commissioned33 years after discovery of the deposit and followed an intensive four-year feasibility study that included a full-scale pilot test. The nahcoliteis co-mingled with oil shale and is impermeable. Solution mining is achieved by a combination of thermo-mechanical cracking and dissolution. Elevated temperatures are required to initiate the thermally induced cracking and to enhance solubility of the nahcolite, which is highly temperature dependent. This paper will provide an overview of the development of the project from discovery, characterization, pilot testing, permitting and commissioning, with emphasis on the solution mining aspects.

Jan 1, 2003

By K. Y. Haramy, B. T. Brady

A scale-invariant theory of the strength and deformability, of rock masses in static equilibrium and at incipient failure is proposed The theory provides a rationale, for designing structures in rock. This paper presents results of experiments conducted by the US Bureau of Mines and presents theoretical methods to determine and interpret the in situ strength of rock masses using the borehole shear tester.

Jan 1, 1996

By K. A. Natarajan, J. M. Modak

A review of published literature on the biosorption of metals using nonliving biomass is presented. Factors such as pH, temperature, initial metal concentration, biomass loading, the presence of co-ions and the pretreatment of biomass influence the metal uptake by biomass. Although few generalizations are possible, unified theories regarding the mechanism of uptake are not available. Therefore, the above aspects of metal biosorption have to be defined individually for each biomass and metal-ion pair.

Jan 1, 1996

By Todd L. Hollingsworth, Jeremy K. Hobbs

In 2001, the Radomiro Tomic Mine located near Calamq Chile, added a tertiary crushing facility. An 84" wide mobile tripper is used to fill their tertiary crushing storage facility. This paper is a we study to demonstrate the drive and control systems in use on the tripper. Of special note is the design concept used to allow the system to operate multiple motors in both demand and regenerative modes through a single VFD. Also noted is the use of touch screen local controls, handheld radio controls, starting/stopping/ braking philosophies, safety device interfaces, and the local to remote control interface.

Jan 1, 2004

By Issac Douglas, Sheila Devasahayam, John S. Thella, Manoj K. Mohanty, Jeremy Prishmont

The flotation performance of Sodium O, O-diisobutyl Di thiophosphate (referred to as reagent A) was compared with Aerophine 3418A (referred to as reagent B) for floating a complex copper ore grab sample (Ore A). Preliminary test results indicated a cumulative copper concentrate grade of 10.19% with a recovery of 86.31%, which was achieved with reagent A from a feed consisting of 5.32% Cu. The grade and recovery achieved using reagent B are 9.11% and 87.85%, respectively. A comparative analysis based on the preliminary test results indicated that reagent A’s performance is better than that of reagent B at lower concentrate grades, specifically below 12% Cu. However, the flotation performance is better for reagent B at higher concentrate grades (>12% Cu). A more detailed study was conducted to optimize the grade-recovery performances achievable from both reagents on a complex low-grade copper ore sample (Ore B) from Western USA. Test results indicated a copper concentrate with a grade of 5.5% Cu and 78.59% recovery was obtained with reagent A compared to 4.31% Cu and 62.04% recovery with reagent B from a feed consisting of around 0.25% Cu.

Feb 22, 2026

By D. Wheeler

Similar to modern day petro-chemical processes, the flotation column is a complete break from the conventional manner of floating on a batch basis in cells. The column has a reputation of being only suited for cleaning applications, particularly that of molybdenum cleaning. The original column, invented and developed by Column Flotation Co. of Canada, Ltd., was developed as a Rougher-Scavenger. Only after proving its capability in this field was cleaning allowed. One rougher-scavenger column in closed circuit with a cleaner column produced better grade and recovery than a conventional cell plant consisting of one stage of roughing, two scavenging and four stages of cell cleaning. Three cleaner columns replaced 13 stages of conventional cell cleaning and resulted in higher grades and recoveries. The gentle countercurrent action of the column itself together with complete automatic control enable this machine to produce such results.

Jan 1, 1986

By F. N. Kissell, H. K. Sacks

This study examines the accuracy of area sampling for measuring the dust exposure of mining machine operators in coal mines. The specific objective of this research was to find locations where an area sampler might work better than earlier studies have indicated. The results show that fixed-location area sampling cannot accurately predict the dust exposure of a machine operator, even when the best fixed location is sought, the fixed location is quite close to the operator and the bias due to the dust concentration gradient is corrected. Industrial hygienists have known for many years that area sampling is unsuitable for measuring air contaminant exposures in the workplace. Near contaminant sources, the dilution air and the contaminants are not evenly mixed. Therefore, when workers are near contaminant sources, exposure measurements must be taken from the worker's breathing zone to be accurate.

Jan 1, 2003

By B. K. Parekh, W. M. Goldberger

Sludge obtained during the production of magnesium (Mg) from molten MgCl2 by electrolysis contains entrapped magnesium particles. The sludge containing the magnesium particles is a friable, continuous matrix of frozen salts that may also contain some oxides and impurities. Due to the high reactivity of magnesium metal with water, a dry process was developed to recover magnesium metal from the sludge. The process utilizes mineral-processing unit operations. The steps include selective comminution, screening, attritioning and tabling. Recovery of the high-grade (>90%) metal was in the 70% range. The novel process was also successfully applied to a magnesium-alloy for the recovery of metal from the sludges.

Jan 1, 1997

By Raj K. Rajamani, Ilesh M. Shah

Maintaining pH, a routine requirement in many industrial processes, is by no means trivial. The control is troublesome because of the inherent nonlinearity and frequently changing process dynamics. Many researchers in the past have investigated advanced on-line estimation and/or adaptive control techniques to overcome these difficulties. Most methods require the development of a complex mathematical model. The present work deals with the use of a simple and elegant method for pH control, based on the use of fuzzy logic. First, a standard fuzzy-logic controller is discussed, followed by a self-organizing controller. The latter algorithm generates a set of rules based on observation of the process. Thus it is a learning algorithm. The development and application of the algorithms to a laboratory acid-base neutralization experiment are presented. This elegant technique is powerful and deserves attention in mineral pro- cessing.

Jan 1, 1990

By Reinhard Gertl, Maximilian Weithaler, Harald Kammerer, Juan Pablo Muñoz, Juan-Carlos Rueda

The Guillermo Gaviria Echeverri tunnel and its access roads project in Antioquia, Colombia is a mega infrastructure project that includes a road network with the longest tunnel in Latin America and several short tunnels, the latter being the focus of this study. The design of the project required careful consideration of several special factors, such as the tunnels’ steep slopes of up to 5%, high fire load of 100 MW, bidirectional operation, and short lengths that make it difficult to place ventilation equipment. The combination of all these parameters cause a challenging design problem for the ventilation systems and smoke control of the short tunnels. To address this challenge, a risk assessment study was conducted to support the design of a new and innovative ventilation strategy that deviates from relevant guidelines and standards, like the Austrian RVS [1][5][6] or the German EABT [8] in order to provide a customized solution for this particular project. This strategy resulted a cost-effective solution, that allowed a reduction in the number of required jet fans and at the same time reaches or reduces the risk level compared to traditional ventilation strategies.

Jun 13, 2023

By M. G. Karfakis, K. P. Chong

Determination of fracture toughness using the semi-circular specimen, the chevron edge notch round specimen, the short rod specimen and the cylindrical burst specimen, are critically reviewed. These methods, among all, are the most applicable for fracture toughness determination of rocks. They require minimum machining. Samples are small, and testing procedures are simple. They have a sound analytical basis and allow the fracture toughness to be determined without measurement of fracture length.

Jan 1, 1986

By Kenneth A. Pietila

The thickening and dewatering characteristics of refuse slurries are as variable as the coal mining operations and preparation plants that create them. This paper discusses these characteristics based on field studies at a number of mine sites. The connection between bench and full scale performance is confirmed with the design, construction and operation of an integrated 18m (60 ft) diameter thickener and 2.5 meter belt filter press system in Western Kentucky. The data from this system are presented.

Jan 1, 1984

By A. Davaliev, K. Hrkovic, V. Pavlovic

On the territory of Macedonia in South Yugoslavia primary and dory gold occurences were known since ancient times. Remnants of numerous goafs and remainders of washaries on river terraces and alluviums date right back to the times of Phillip II and his son Alexander of Macedonia and from Roman times, as well as from the Middle Ages witness exploitation of primary and secondary gold. More recent explorations on primary and secondary gold occurrences date from the period between two World Wars. Over that period a number of private companies, each on their own jointly, carried out gold exploration, particularly of alluvial occurrences on rivers emptying into River Vardar, starting from Skopje to the Greek frontier. The latest gold explorations carried out In the alluvium of River Konjska date back in 1976, and in 1978 old terraces of River Konjska were explored. The Visibility Study was prepared on possibilities of exploitation of gold from River Konjska alluvium. In the paper are collected the basic date an all known primary and secondary occurrences of gold, the results of the latest explorations, and the study itself. To-date geological explorations and analyses show very interesting potentionality of River Konjska and River Vardar alluvium, which proves continuing of he further explorations. For the moment, it is necessary to re-explore more complete view of the deposit. After that it will be possible to make complete techno-economical estimation of the auriferious alluviums and the conditions of the evaluations of the alluvial gold. 1. REVIEW OF PRIMARY AND SECONDARY GOLD DEPOSITS IN MAOEDONIA,YUGOSLAVIA 1.1. Primary deposits Scarse data are available for primary gold deposits in Macedonia` being unadequate for clear

Jan 1, 1988