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By Charles R. Jenkins

Three sedimentation ponds had their performance evaluated before and after installation of modifications. Each pond had a floating baffle installed, two had siphon outlets and one had a floating outlet device. Baffles inhibited short circuiting, and the outlet devices retarded flow following a rainfall event, and drained the pond creating a large storage volume to maximize detention time. Total suspended solids and settleable solids tests were run on samples of influent and effluent to evaluate pond performance. Particle size analyses were run on samples containing measurable amounts of solids. Performance improved in each pond, with baffles providing the major improvement. Through the entire surface mining process un- protected soil is exposed to direct rainfall and subject to accelerated erosion. Without controls, receiving streams would be "choked" by the additional sediment load. Several states, including West Virginia, require that sediment control ponds be constructed to trap the sediment before the water enters receiving streams. Even well designed ponds have exhibited difficulty in meeting effluent limitations. In a study supported by EPA, about half the ponds did not meet effluent limitations (1). There is a critical need to reduce sediment losses using presediment pond controls or by improving sediment pond performance. The objectives of this study were to evaluate modifications designed to improve sediment pond performance by; 1) monitoring three ponds prior to modification, 2) install floating baffles and 3) modify the principle spillway and determine the change in pond performance.

Jan 1, 1985

By Thomas J. Ferree

A Reichert cone concentrator was installed in an aggregate plant circuit to recover the extremely fine "flour gold" known to exist in the deposit. The gold content of the bank-run gravels averages about 0.1 grams per ton (about $1.45 per ton), based upon $14.47/g (345O/ounce) gold. Tine Reichert cone, in conjunction with a conventional shaking table, re- covers in excess of 85% of the gold. A screen analysis of the gold particles shows 44.1% is -i4 microns (-200 mesh) in size. The plant operates with a two-man crew.

Jan 1, 1981

By A. S. Kastrinos

There are many concepts of preventative maintenance. The basic objective of all maintenance organization, however, is the efficient (accomplishment and control of all) inspection, repair, overhaul, material and preventative maintenance functions necessary to maintain facilities and equipment in a condition that will meet operating requirements at a level consistent with low costs and high availability. To formulate a preventative maintenance program requires sound judgment and the ability to apply in a practical manner a system that meets Plant operation requirements, based upon organization, experience, conditions, design and historical data. A maintenance program must be divided into to categories consisting of: 1. Scheduled tasks to be accomplished at planned intervals. The objective of these tasks is to maintain reliability and prevent as much as possible abnormal failures. 2. Non-scheduled tasks that result from periodic reports and which can be scheduled to fit in conveniently with other routine work. The non-scheduled work items may include long-range preparation for lenghty shutdowns requiring Engineering and Shop services.

Jan 1, 1975

By H. Wesley Peirce

Arizona, in 1966, has continued to be the site of an extensive and intensive search for metallic mineral deposits. Over fifty separate entities--companies and individuals--have been actively engaged in mineral exploration programs, both large and small, in the Basin-and-Range portion of the State. Certainly, copper has been primarily responsible for the major efforts, although associated gold, silver, and molybdenum mineralization also has been important in the economic evaluation of potential copper deposits. It is not difficult to explain why the Basin-Range portion of Arizona is receiving such attention. Part of the story, undoubtedly familiar to most, can be illustrated by reference to three graphical presentations. For example, Figure 1 shows Arizona's annual copper production for the period 1955-1965, inclusive, and it demonstrates that new records of production have been accomplished in each of the past 6 years and in 9 of the last 11 years.

Jan 1, 1967

By Jose Agapito

Roofbolts with expansion anchors have been used at White Pine for more than twelve years, but always with an understanding that their performance was not entirely satisfactory. Some bolts fell out, some were obviously loose, and, when roof failures did occur, very few bolts actually broke. Obviously, there was an anchorage problem. A program was started in May, 1967, to define the problem and to solve it. This paper describes briefly those parts of the program which led to the development of a roofbolt assembly which performs much better in the medium-hard rocks at White Pine. As a result of the changes, significant improvements were found in the torque:tension, tension loss, and pull tests.

Jan 1, 1970

By G. T. Lineberry

There is a critical need for effective instructional materials at the university level and for an upgrading of mine safety and health in the mining engineering curriculum. A fundamental approach to mine safety and health is recast into the familiar 3 E's: engineering, education, and enforcement, in that order. Each is briefly reviewed and their interdependence emphasized. A unique philosophy for successfully integrating safety and health principles into the mining engineering curriculum is offered. The concept of textbook ?tailoring? is discussed and defended, permitting rapid assemblage and synthesis of existing educational materials. Final recommendations are made for a u, comprehensive approach to mine safety and health education in the undergraduate curriculum.

Jan 1, 1987

By C. L. Jiang

The role of iron ions (Fe2+ and Fe3+) in the flotation of both ore-and coal-pyrite with ethyl xanthate was comparatively investigated. The complete/partial depression of ore-and coal-pyrite in neutral to weakly alkaline solution is due to the formation of ferric dihydroxy ethyl xanthate between xanthate and the oxidation products of pyrite, ferric and ferrous ions. With xanthate as collector, coal-pyrite was found to be nonfloatable above pH6. In the presence of iron ions and between pH6-9.5, the flotation of ore-pyrite was significantly depressed. Ferrous ions have a stronger effect on pyrite flotation than ferric ions in neutral to weakly alkaline solutions.

Jan 1, 1996

By Fred H. Lightner

The feasibility evaluation of the Borealis project of Houston International Minerals Corporation (HIMCO) was initiated in October of 1980. The operation of the Borealis Mine and heap leaching plant began in late 1981. In order to achieve the rapid development schedule several items were necessary: 1) Pre-planning of environmental requirements and early study of key issues. 2) Adoption of conservative design criteria. 3) Coordination and cooperation between HIMCO and regulatory agencies. 4) Adoption of specialized engineering and construction procedures. 5) Careful evaluation of owner project management philosophy.

Jan 1, 1982

By William E. Robinson

Why did it fail? My first reaction when assigned this topic was to say: because somebody "goofed"--then thank you all for letting me say those few words, then promptly sit down. All of you have been bandying this problem around for many years--so all of a sudden I should come up with the solution. Well, While I might not provide you with your particular answer, I think I can show you some of the resolutions to it. Somewhere along your path of experience you may have discovered that a good formula for starting a fight is to tell a group of dedicated (Nordberg Crusher) users they should be using (Allis-Chalmers), or a group of (Allis-Chalmers) 'users they should be a (Traylor). Now, if you really want a melee, get both groups together and tell them they should be using a (Stedman Cage Mill). This is one sure way you can learn how great minds arrive at logical, well thought-out conclusions, based on all the relevant facts. Why did it fail? I could go on for hours giving you specific reasons why. One of my engineering professors used to start his new class off each year by writing on the blackboard--four and two, then turn to the class and ask: What is the problem? One brave scholar would venture to answer 8. His head would shake no. Another would dare 6. Again, a head shake. Now that the ball had gotten rolling, a number would vocally decide it had to be two, which produced only another shake of the head--no. All of them had missed the question he had asked : What is the problem? What he had gotten ,were some of the possible answers to the problem.

Jan 1, 1977

By J. K. Brooke

Fluorine is a lively element in both its chemical and economic behavior. It was not isolated as an element until 1886 by Moissan. However, its principal source to this day, fluorspar, was known and its special merits recognized long before that time. Our own mining brother, Agricola, is credited with having named fluorite, the mineral name, in 1546 from the Latin, "fluere", to flow. It made things melt and was already being used as a flux. Because fluorspar has been found as a relatively common gangue mineral in metal ore veins, it has long attracted the attention of geological thinkers seeking to, explain the whys and wherefores of veins. Fluorine has been thought of as one of the principal mineralizers, holding metals in ascending vein solutions for deposition close enough to the eventual surface to be accessible for profitable mining.

Jan 1, 1964

By Paul L. Bearden

The accumulation, handling, and utilization of sludges formed from wet process phosphoric acid is one of the major problems in the industry. The purpose of this paper is to explain some of the considerations and techniques that can be employed to provide some measure of control over the problem. An acid made from a Central Florida phosphate rock is used to illustrate the effects of one process design approach used to provide one type of control. Other approaches or techniques are discussed on a general basis. In every case, the discussion is purposely limited to conventional dihydrate processing in which phosphoric acid is produced from the filter at a strength of approximately 30% P205 and is subsequently concentrated to higher strengths such as 44 and 54% P205.

Jan 1, 1966

By Martin N. Kelley

The Great Belt Link is a $3.5 billion fixed link across an 18 km (12 mile) wide body of water that separates the island of Zealand, on which Copenhagen is situated, and the main land mass of Denmark, Jutland, which is part of the European continent. The project consists of three main contracts. The first contract is an 8 km (5 mile) long, two-bore railway tunnel for the eastern half, the second contract is a 6.6 km (4 mile) combination railroad and highway bridge for the western half, and the third contract is a 6.7 km (4 mile) long high-level highway bridge for the eastern half. This paper will discuss the Eastern Railway Tunnel Project and the methods of construction that the joint venture consortium plans to use, along with its equipment selection. The ground conditions to be encountered begin with glacial tills, which are a mixture of clay, silt, sand, gravel, cobbles, and granitic boulders. The boulders can be up to 1-3 m (3-10 ft) in diameter. Underlying the till is a marl which is sometimes highly fractured with hydrostatic pressures of up to 8 bar. About 40% of the tunnel is in till and 40% in marl, with the remaining 20% being a mixed face of the two formations.

Jan 1, 1991

By J. W. Scott

The problems involved in installing, maintaining, and operating large vibrating screens have been summarized and discussed, based on a survey of current use of such screens in selected North American mineral processing applications. Practical, effective solutions for the more serious common problems are described, along with some recommendations on design practice for specifying, selecting, and installing large screens.

Jan 1, 1983

By Daniel McNamee, Wern-ping N. Chen

The Amtrak East River Tunnels include four tunnels, Line 1 to Line 4, which extend from New York Penn Station in Manhattan, under the East River to Sunnyside Yard in Long Island City. Since fall 2015, Amtrak has initiated a program to repair and reconstruct the century-old tunnels, including structural repairs of all the tunnels and reconstruction of the Line 1 and Line 2 tunnels. The reconstruction includes bench wall demolition and replacing and installing the following elements in the tunnels: direct fixation track, traction power, signal, communication, and tunnel fire/life/safety components. This paper provides design and site investigation challenges and knowledge gained from this program.

Dec 1, 2022

By Jeff Fontana, Daniel Ebin, Eric Westergren, William Currier

The PMott MacDonaldlane Train Tunnel West Extension (PTTWE) Project at HartsfieldJackson Atlanta International Airport includes the extension of the existing automated people mover system and terminal renovations at the baggage claim station. To assist with design, pricing, and assessment of risk on this progressive design-build project, 3D design models were prepared to increase visibility into realities of construction. This paper will focus on the original intent of the models and explore the additional, unforeseen value they provided throughout the design and construction process.

Dec 1, 2022

By Brian Young, Ben Pantony

Interferometric Synthetic Aperture Radar (InSAR) has played an integral role in many large scale tunneling projects globally. Until recently, it has been regarded as a complementary monitoring tool. On the Los Angeles Metro Purple Line Phase 1, InSAR was proposed as a primary means to replace weekly and bi-weekly surface monitoring requirements on surrounding critical infrastructure. This paper will summarize the statistical analysis approach engaged in order to compare and contrast a year of historical InSAR data to known geodetic survey data, in order to utilize InSAR as an operational monitoring tool on this project.

Jun 13, 2021

By Giuseppe Gaspari, Xiangrong Wang

The pandemic emergency is forcing transit agencies to define strategies allowing social distancing, which are more challenging in underground interchange stations in crowded downtown cores. Toronto Transit Commission’s (TTC’s) Bloor-Yonge Station Capacity Improvement Project in Toronto was approved to meet increasing demand and represents an opportunity to fight COVID-19. This paper discusses cost-effective solutions in expanding the cut-and-cover station box over the existing Toronto Subway Line 2 and connecting it through ventilation openings in the cast-iron tunnel liner. Potential uplift risks and structural damage due to minimal vertical clearance were analyzed via three-dimensional finite element analyses with advanced constitutive laws to simulate the multi-stage construction process. Based on the simulation results, a series of countermeasures, including excavation support systems, king posts, ground-consolidations, and liner reinforcements were integrated into comprehensive design options to ensure the serviceability and structural integrity of the subway tunnels.

Jun 13, 2021

By Eduardo Velasco, Paz Navarro, Alfonso Navarro, Claudio Cimiotti, Alejandro Sanz, Nick Karlin

The LA Effluent Outfall tunnel is a 7-mile long, 18' internal diameter, secondary treated effluent discharge tunnel currently under construction by Dragados USA for the Los Angeles County Sanitation District No. 2 (LACSD). The purpose of this tunnel is to add redundancy and increased capacity for discharge of secondary treated effluent from the LACSD’s Joint Water Pollution Control Plant, located in Wilmington, California within Southern Los Angeles County. Current discharge from this facility flows through two existing tunnels of 8' and 12' horseshoe profile, constructed in 1937 and 1958, respectively. When the new tunnel is complete, it will add an additional capacity of 670MGD in peak wet weather flow conditions. Geology of the roughly 7 mile long tunnel was divided into six reaches by the contract documents. Tunnel Reaches (TR) 1 to 3, comprising 19,550' will be excavated in alluvial sands of the San Pedro and Lakewood formations, with cover ranging from 45 to 90 feet. In this reach the tunnel intersects the seismically active Palos Verdes fault Zone. TR 4 is a 1,600' transitional zone between alluvium and the rock formations of the Palos Verdes (PV) Hills, comprised mostly of Malaga Mudstone. TR’s 5 and 6 total 15,591', and are within the rock formations of the PV Hills with overburden ranging from 315' to 475'. The primary constituent of the PV Hills is Altamira

Jun 13, 2021

By Paul Taurasi, Mahmood Khwaja, Anjuli Corcovelos, William Brick

California’s San Diego County Water Authority provides a safe and reliable water supply to more than 3.3 million residents through twenty-four member agencies. The 2nd Aqueduct pipelines, a critical infrastructure consisting of three large-diameter pipelines, are susceptible to natural threats including streambed erosion, channel migration, and seismic hazards within the 3,840-foot-long Moosa Canyon segment of the alignment. A state-of-good repair, hazard mitigation, and resiliency project is progressing to ensure uninterrupted water supply. For each pipeline, a segment will be replaced by tunneling. A high-level project development approach is presented, focusing on alternative selection, environmental and geotechnical considerations, and operations and maintenance constraints.

Jun 13, 2023

By Eugene E. Hively

The Tower Kill is a vertical "stirred" ball/pebble mill recently introduced in the Western Hemisphere. This device offers a significant power savings on wet fine grinding applications when compared to conventional tumbling mills. This paper describes the laboratory application of this mill wet grinding hydrated alumina to products of 50 percent passing 2 to 6 microns.

Jan 1, 1983