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By W. S. Sadik

This paper presents the ventilation design for an underground testing facility in a salt medium. The underground workings consist of two-12 ft. (3.66 m) diameter watertight shafts and approximately 6000 ft. (1830 m) plus of drifting. These facilities are designed for the purpose of providing access for an in-situ testing of a salt horizon in which a variety of hazardous and non-hazardous materials could be temporarily stored or permanently deposited. The ventilation system includes a design basis for gassy mine conditions and provides for the option of bulk air cooling and heating.

Jan 1, 1988

By Paul I. Eimon

Mineral exploration involves the selective collection, organization, evaluation, and interpretation of geologic and economic data. The sources for such data are original field observations and existing documented information of various types (publications, reports, maps, company files, etc.). As exploration data are accumulated, their storage, organization, indexing, and J retrieval is key to exploration progress. Initial use of computers by mineral exploration groups indicates that data can be meaningfully handled by machines. A computer system makes possible: 1) the storage, manipulation, collation, and selective retrieval of data; 2) the utilization of data banks developed by geologic service groups and available at relatively low cost; and 3) the retrieval of stored data more rapidly, completely, and effectively than by manual systems. Profitable utilization of these capabilities is conditioned by several factors, particularly by the information selected for the system data base and by the design of the computer system itself.

Jan 1, 1968

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

By Edward M. Dowey

This paper presents the excavation of the Roosevelt Island Valve Chamber, the final of three chambers in Stage One of New York City's Third Water Tunnel. The valve chamber and passageways 13 379.7 cu m (17 500 cu yd) are drilled and blasted. The rock is stabilized by grouted rock anchors. The 6.1 m (20 ft) diameter shaft is drilled, blasted, rock bolted and wire meshed for a depth of 70.7 m (232 ft). Then shaft excavation proceeds with immediate concrete lining for another 120.7 m (396 ft). Two 6.1m (20 ft) diameter manifolds are excavated using heading and bench. The raise drilling of eight 3.7 m (12 ft) diameter laterals occurs during lower shaft sinking.

Jan 1, 1987

By Kevin Fitzpatrick, Carmen Scalise, Patrick Jensen

"The Metropolitan Water Reclamation District of Greater Chicago (MWRDGC) owns and operates the Tunnel and Reservoir Plan (TARP) system which was adopted in 1972. TARP is a network of 110 miles of deep tunnels and ultimately 3 large reservoirs to combat waterway pollution and flooding within a 350 square mile area served by combined sewers. The original TARP concept included additional tunnels to convey CSOs from the largest storms to the reservoirs. With the initial TARP tunnels complete and the reservoirs nearing completion, MWRDGC commissioned hydraulic and hydrologic modeling studies to analyze the benefits of additional conveyance tunnels. These updated studies optimized the configuration of additional tunnels considering integration with potential future local sewer system upgrades. The alternatives considered several routes of 25, 30, and 35 foot diameter tunnels, ranging from 10 to 18 miles. Alternatives were analyzed based on projected reductions to basement flooding compared to the relative costs. TUNNEL AND RESERVOIR PLAN After World War II the Chicagoland area underwent rapid growth and development. With the Metropolitan Water Reclamation District of Greater Chicago's (MWRDGC) service area becoming increasingly impervious, the flat Chicago landscape was increasingly at risk of significant flooding. In the mid and late 1950's, Chicago experienced multiple extreme storm events that had significant impacts on the city and generated the momentum necessary to initiate what would ultimately become one of the world's largest civil works undertakings. In 1957 a Flood Control Coordinating Committee was formed, consisting of representatives of the MWRDGC, Illinois Department of Public Works, Cook County, and the city of Chicago, to review various plans and develop recommendations for a course of action. With more than 50 alternative concepts being identified, the Tunnel and Reservoir Plan (TARP), which itself is a composite of various alternatives, was adopted the by the Metropolitan Water Reclamation District of Greater Chicago (MWRDGC) in 1972. The need to adopt a long term plan was further influenced by the Clean Water Act, which was enacted only 8 days prior."

Jan 1, 2016

By Mary Fu, Helen Leung, Colin R. Phillips

In uranium mines, the median size of the aerosol has been found to be about 0.1 micron or less. Such small aerosols are readily deposited or "plated-out" on dosimeter interior surfaces resulting in the recording of a low dose. The "plate-out" properties of the CEA alpha dosimeter head are described with respect to aerosol properties in controlled experiments in the laboratory. A simple model is derived to estimate the amount of "plate-out" in the CEA head.

Jan 1, 1981

By K. Thirumalai

The Bureau of Mines has developed and tested a new concept of combining thermal and hydraulic energy processes for hard rock cutting. The study shows that this novel combination method overcomes the fragmentation limitations of the thermal process in nonspalling rocks and the cuttability limitations of the hydraulic process in high-strength rocks. The method effectively cuts hard rocks at moderate hydraulic pressures (below 30,000 psi). Theoretical predictions of the rock damage process are made and are correlated with experimental results obtained by using both single pulse and continuous water jet hydraulic systems. Traversing point heating and line heating techniques were used for heating rocks preceding the continuous jet impingement. Heating induces structural weakness of the rock material and assists fragmentation by the water jet impingement. The thermohydraulic process is effective if the significant depth of heat penetration induced by the surface heating exceeds the cutting depth produced by the jet impingement. Hydraulic specific fragmentation energy values reduce by about an order of magnitude using the combination technique. The process efficiency and the rate of themohydraulic hard rock cutting increases significantly by increasing the intensity and duration of heating.

Jan 1, 1973

By Arthur B. Steiker

Digital simulation was used to model a proposed underground' train system. The trains are to haul ore from numerous loading points beneath the production area of the mine to a central underground dump location, and then return to the mine. The purpose of the simulation was to aid mine engineers in studying various alternatives and configurations regarding track layout, crusher (dump point) specifications, dispatch procedures, fleet size, and train length, among others. The simulation' model can also be used to study the same aspects of existing haulage systems. To accommodate a wide and initially unknown range of system designs, a modular model structure was developed with major components devoted to track routing, train movement, loading process, dumping process, and dispatch. Key statistics tabulated were number of trains dumped during a simulated week, queueing delays in the mine and at the crusher, crusher utilization, cycle time, and percent of time for each: activity (loading, moving, dumping, etc.). The simulation results were instrumental in identifying a train system design which would reduce queueing delays and meet production goals with a minimum of trains and track mileage.

Jan 1, 1982

By Rick McGregor, David Blowes, Mike Choi, Ralph Ludwig

The oxidation of sulfide minerals at an ore transfer location in Western Canada has resulted in widespread contamination of underlying soil and groundwater. The oxidation of sulfide minerals has released sulfate [SO,] and heavy metals including cadmium [Cd], copper [Cu], nickel [Ni], lead [Pb], and zinc [Zn] into the groundwater. A compost-based sulfate-reducing reactive wall was installed in the path of the plume in an attempt to reduce the potential impact of the heavy metals on a down-gradient marine inlet. Monitoring of the reactive wall over a 21-month period has shown that Cu concentrations decrease from over 4000 ug/L to less than 5 ug/L. Cadmium, Ni, Pb, and Zn concentrations also show similar decreases with treated concentrations generally being observed near or below detection limits.

Jan 1, 2000

By Keith A. Heasley

The objective of this paper is to back-analyze the August 6th ,2007 collapse at the Crandall Canyon Mine in order to better understand the geometric and geo- mechanical factors which contributed to that collapse. In this work, the LaModel boundary-element program along with the best available information is used for the back- analysis. To initiate the analysis, a six step base model of the mining in he Main West area was developed. This base model included a step for each of the critical stages in the mining of this area. Next, calibrated values for the critical input parameters: rock mass stiffness, gob stiffness and coal strength, were developed and optimized based on the best available information. Finally, the model was used to simulate the final mining scenario. As a result of this back analysis , a number of conclusions can be made concerning the mine design and the August 6th collapse: 1) Overall, the area was primed for a massive pillar collapse because of the large area of equal size pillars, 2) The abutment stress from the active retreat sections and the adjacent longwall panels were significant contributors to the collapse, 3) From the modeling alone, it is not clear exactly what triggered the August collapse, although the active mining is a reasonable assumption.

Jan 1, 2012

By R. Sandefur

Recent advances in personal computer technology allow movies of various types to be made and displayed on PC and Macintosh computers. An interesting application of this movie technology is animation of computerized geological models. These movies, which can be most easily constructed along rows, columns, and benches of block models, allow an ore body to be more easily and quickly visualized than the traditional method of flipping back and forth through various sections.

Jan 1, 1994

By Frederick T. Graybeal

Silver Bell is located about 56 km (35 miles) northwest of Tucson, AZ. It is a classic porphyry copper deposit containing enriched disseminated chalcocite ore in altered porphyritic rocks with chalcopyrite in adjacent skarn zones. The discovery of Silver Bell was an evolutionary process that occurred over a 75-year period. Recorded mining activity began about 1865 on Boot Hill east of El Tiro pit (see Fig. 1) where outcrops of altered limestones were found to contain 425 to 482 g (15 to 17 oz) Ag mixed with copper oxides. By 1874, the Young America Copper Co. was mining shallow occurrences of 30% Cu along the north side of the present Oxide pit. The ore was shipped by wagon to Yuma, AZ, and then by boat to San Francisco for smelting. By 1881, the district supported several mining companies, two small smelters, and was being favorably compared to Bisbee in local newspapers. Most of the ore mined in the period 1865-1903 came from pods of massive sulfide or their oxidized products which were distributed in an unpredictable fashion through a large skarn zone in Paleozoic limestone east of El Tiro pit. Ore grades varied from 5 to 10% Cu.

Jan 1, 1991

By Lynn B. Hales, Randy A. Ynchausti

Introduction There continues to be a large economic opportunity associated with improving process performance through advanced process control systems within the minerals industry. The basis for this opportunity lies in the inherently low efficiencies of many of the unit operations found in mineral processing plants as well as the continual variation that is present in the ores being processed. The ageless target of such control systems is improved recoveries and concentrate grades, higher processing rates and lower unit costs. Many plants are enjoying the benefits of modem, well functioning process control systems but few if any have achieved plant-wide optimization in an economical sense. As new process modeling and control technologies, such as neural networks, continue to evolve and develop, the potential for plant- wide optimization is becoming a closer reality. Neural network technology appears to have a significant potential in the general field of process control and control of mineral processing operations. Neural networks are an emerging technology that have been evolving out of the study of biological systems since the early 1940's. The first software simulation of neural computing networks was reported in 1956 by Nathanial Rochester of IBM Research during the first conference on artificial intelligence which was sponsored by the Rockefeller Foundation. Neural Networks Neural networks can be considered to be a class of computer program that perform their problem solving functions based on a rudimentary model of the human brain and how it solves problems. Traditional computer programs and even computers themselves solve problems or process data sequentially and in a deterministic manner. The human brain, on the other hand, processes data and solves problems in a massively parallel fashion. We think of computers normally in terms of having a single processing unit, sometimes a co-processor to assist in certain activities such as mathematical functions or communications, bytes of memory, processing speed and program/data storage size.

Jan 1, 1992

By Samer Sadek, Phoebe Cheng, Changmo Kwon, Myat Ohn

BART Facilities Standards (BFS) Structural Criteria is a living document that governs planning, design, and construction of all BART projects. Since its development, the document undergoes incremental changes and updates to reflect policy changes, changes in local, State, or national design codes and guidelines, advancements in engineering and technology, or based on the performance of past built infrastructure. In 2020, the BFS-Structural Criteria underwent a comprehensive update and was released with BFS version 3.2. This paper summarizes the updates to the Tunnels and Underground Structures Section of the Structural Criteria, and provides insights to the basis and logic of the requirements.

Dec 1, 2022

By Laurence E. Snow

The conversion to the use of commercial grade ammonium nitrate (CGAN) for use in blasting at the Utah Copper Pit of the Kennecott Copper Corporation has presented unique problems for the Drilling and Blasting Department, In order to better understand these problems, a' picture of the Bingham Pit might be helpful. Some quarter of a million tons of ore and waste must be blasted daily in order to keep thirty-eight electric shovels operating. All material is blasted by "toe holes" of 24 to 28 feet in depth, drilled from prepared drill grades and sloped so as to bottom approximately 5 feet below the bench level. Horizontal spacing of these holes averages 22 feet, with exceptions being made where faults occur in the bank. These "toe holes" are drilled by 4-inch drifter machines, mounted on self-contained mobile drill units using .3-inch starter bits and bottoming at a minimum of 2 1/2 inches in diameter, "Toe-hole" drilling amounts to about two-thirds of the total drilling. In the higher bank sections of the Mine and wherever necessary, single rows of "down holes" are drilled to 28 feet in depth and spaced, on the average 23 feet apart. These holes are also drilled by a mobile drill. "Down hole" drilling amounts to about one-third of the total drilling.

Jan 1, 1959

By D. K. Grubbs

Red bauxites from Breadnut Valley, Clarendon Parish, Jamaica, are very homogeneous in texture. Bauxite minerals are uniformly distributed in a groundmass, the predominant grain size being smaller than l um (Figure 1 Although the deposits have a massive, non-stratified structure, they all seem to have been affected by postformational faulting which is evidenced by shear zones running subvertically through the deposits. These shear zones stand out very clearly because of a yellow staining along their faces. Often yellow zones, ranging from a few m to several cm in thickness, have developed. When the shear zones are cut at an angle, they appear as yellow veins. Near the surface of the deposits, yellow material forms shallow irregular lenses (Figure 2). In most cases, tree roots (hair roots), or their imprints, are associated with the shear zones or stained areas. In fact, the yellowish color is especially pronounced along these roots and often disappears where the roots end (Figure 3). The mineral composition and texture of red groundmass and yellow zones are markedly different. Secondary phosphate minerals and a higher goethite to hematite ratio characterize the mineral composition of the yellow zones. It should also be noted that Al-substitution in goethite from these areas is significantly higher than in goethite occurring in the groundmass (Figure 4).

Jan 1, 1980

By A. L. Mular

Steady-state material balances calculated from data measured at various locations around process units are useful for many purposes, such as metallurgical accounting, on-line control, and the development of mathematical models. Often it is possible to calculate material balances by several independent procedures when excess measurement information, i.e., redundant data, is available. Clearly, if the data were collected without measurement errors, a theoretical condition never found in practice, all material balances calculated from redundant data would be in agreement. The real situation is that error exists in practical measurements, so that the results of material balances determined from available optional procedures differ. Consequently, best fit computational procedures to improve the material balances by taking measurement errors into account have been formulated. Such procedures can be used also to judge whether measurements are grossly in error due to either faulty observations or defective data sensing devices. A variety of mathematical techniques are available which serve to adjust raw data. The adjusted data permit mass balancing that does not depend on the computational method. To illustrate the need for an adjustment procedure, Table 1 shows a raw data set acquired around the Brenda Mines Ltd. No. 4 grinding circuit shown schematically in Fig. 1. At least seven optional ways to calculate a circulating load ratio may be employed. These are shown in Table 2 where, depending upon the calculation [ ]

Jan 1, 1979

By Harry M. Edenborn, Richard W. Hammack

Experiments were done to determine if a mushroom compost-based sulfate reduction system could be used to treat nickel-contaminated mine waters. Sulfate reduction systems were established in columns containing acid-washed mushroom compost. Simulated mine waters containing 2000 mg/L sulfate and 50 to 1000 mg/L nickel were adjusted to pH 4.5 and pumped through the columns at flow rates between 15 and 25 mL/hr. During the first nine days of operation, virtually all influent nickel was removed in the columns by sorption and ion exchange mechanisms. The nickel removal rate then dropped to 18 to 30 mg Ni/day (7.8 to 12.8 nmol/ g-substrate/day), probably due to low sulfate reduction rates. When sodium lactate was added to the inflow, a sustained and seven-fold increase in the nickel removal rate was observed. Bacterial sulfate reduction rates measured in mushroom compost-based wetlands exposed to coal mine drainage are 2 to 20 times faster than the rates observed in this study. Low sulfate reduction rates in the columns may have been due to the inhibition of microbial activity by high nickel concentrations and the removal of labile organic compounds from the mushroom compost substrate during acid-washing. Results of this study indicate that bacterial sulfate reduction can effectively treat nickel concentrations up to 500 mg/L if labile carbon is nonlimiting.

Jan 1, 1992

By Yuuichi Umeki, Yuusaku Tominaga

In order to keep good air condition in any specific branch such as coal face and/or heading in an underground coal mine, effective factors of all the branches with respect to the specified branch have been investigated, using computer simulation. Main results of the paper are as follows; 1) A branch in a network is classified to one of three classes of effectiveness to increase, to decrease and not to change airflow rate in the specific branch by altering aerodynamic resistance in the branch. 2) Distribution of position of branches, belonging to each class, related to a specific branch is one of the macroscopic characteristic of a network which is the inherent property of every network. 3) A relation of the aerodynamic resistances of any two branches to keep a constant airflow rate in the specified branch is shown as a monotonous curve. 4) Ventilation transition diagram with the rate of airflow in the two branches as coordinates, and for different rates of airflow in the specific branch as the parameter, is found to be straight lines. 5) Existing range of airflow rates In the specified branch is given as a parameter in the enclosed area in the ventilation transition diagram. Moreover, an expert system to assist ventilation control using a transition diagram of airflow rate is introduced in this paper.

Jan 1, 1991

By Ronald J. Searle, Howard S. Latham

In April 1964 the Bureau of Reclamation awarded the first contract for rapid machine excavation of a water conveyance tunnel . Since then the Bureau has excavated seven tunnels with a total length of over 190,000 feet utilizing rapid excavation tunneling machines. Tunnel bored diameters have varied from 9' 0" to 20' 10" (See Table #1) and tunnel lengths from 5,000 feet to 67,000 feet. Driver and cutter units varied from 43 rolling teeth and eight rolling discs mounted on a rotating head driven by five 200 HP 23,000 volt electric motors to 20 discs and one tricone unit mounted on a rotating head driven by two 100 HP 440 volt motors. All tunnels were driven with a laser beam guidance system governing both line and grade. Trailing conveyors and rail haulage systems were used to dispose of the excavated material. Approved Bureau of Mines diesel locomotive engines for waste trains were prevalent power sources supplemented by battery units on some projects. Sandstone, conglomerates, agglomerates, siltstone, shale, and granite were the geological formations encountered, with sandstone and shale the preponderant material . Tunnel support systems utilized were structural steel ribs; rock bolts and metal plates; and shotcrete, or combinations of these. Progress varied from 51-1/2 feet to 154 feet per working day for three shifts, depending on rock material and supports required. One contractor established a record rate of advance of over 400 feet in one day, 1,905 feet in one week, and 6,848 feet in one month. Such diversified experience in underground machine excavation methods presented an excellent opportunity to observe, analyze, and evaluate associated environmental health problems. Also, to develop measures for controlling

Jan 1, 1997