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By David J. Hatem, K. Bhattarai

Effective risk management in major subsurface projects involves ways to mitigate adverse impacts to final design and construction approaches due to changed subsurface conditions. An Early Contractor Involvement (ECI) collaborated with Observational Method will be an effective contractual tool to address risk developed due to encountering differing site conditions. Observational Method (OM) can further be supported with artificial intelligence (AI) technologies with automated data-driven decision-making features in risk mitigation and implementation of proper design and construction approaches. This paper presents collaborative applications of ECI, OM, machine learning, and risk baselining in risk management and productivity enhancement in tunneling projects.

Jun 23, 2024

By M. F. Corcoran

Rapid advances have been made in the past few years in the application of automatic controls and instrumentation to iron ore pelletizing plants. Present practice in applying instrumentation and control to the Grate-Kiln system of iron ore pelletizing is described. Major control points and loops are tabulated. Future trends in the application of digital control including computer data logging systems are described.

Jan 1, 1965

By G. Ferrara

Hydrocyclones and other dynamic separators are normally fed with pulps of water and solid particles. The particles have different sizes, shapes and densities and, except in the special case of mono-characteristic particles, are segregated into size, shape and density. Segregation is magnified by the high values of centrifugal acceleration in the hydrocyclones. This paper develops the theory of the segregation, indicates the major variables involved and reports experimental data of segregation under different operating conditions for mixtures of magnetite and/or ferrosilicon and non-magnetic minerals.

Jan 1, 1995

By T. W. Camm

"We hear all the time about the value of hard work and perseverance, and the part they play in the professional life of successful people. What we do not hear so much about are the many professionals who work hard and persevere, yet never seem to quite reach the level of success they aim for. Some current authors are beginning to give more attention to the part luck/black swans/outliers play in success. This is not a new phenomenon, Machiavelli had a lot to say about it back in the Renaissance. So how can knowledge of this dynamic help in a modern organization? INTRODUCTION Work hard and you will succeed. Go to the right school, major in the right degree, study hard, and get a good job. Look at the lives of successful people, and do what they do. Be all that you can be. You can be anything you want to be. Really? Those who are successful always get attention, people want to know what they did to reach such a high position. Invariably, at least part of their narrative will include hard work, wise insight, taking advantage of opportunities, etc. If they are of a more generous nature, they might also allow that building the right friendships and collaborations also played a role. All of this may be true; what we do not often hear are the stories of those who did all of these very same things, but did not find success. An example from pop culture: The Voice. I have watched this show occasionally the past couple of years. One of the things I like about the show is that the initial screening of contestants is based solely on their singing voice (hence the name of the show), and not on their appearance. At the time of this writing (early November), the judges have just finished elimination rounds for their final teams to go on to the live shows. Here is my point—in almost every case the judges agonized over choosing who would go forward and who would be eliminated. And the reason is because all of them are really talented singers. It is impressive how gifted they are. At the end of each season, only one is declared a winner, out of that gifted pool of singers. When you hear their stories, they are all talented, hard-working individuals sacrificing for their art. And as far as I know, none of them has ever become a star. Hard work, dedication, sacrifice, talent—sometimes it is enough, sometimes not. I will be looking at the part uncertainty/luck/black swans play in our lives, but I want to make it clear at the beginning that I am not saying everything that happens to us is out of our hands or beyond our control. Taleb makes this same point (2007, p. 52): “This problem is chronic: if you tell people that the key to success is not always skills, they think that you are telling them that it is never skills, always luck.”"

Jan 1, 2017

By J. R. Evans

In order to patent an industrial mineral placer mining claim, it must incorporate an economic deposit. Each ten acre parcel is evaluated for its mineral -in -character nature. Nonmineral -in -character parcels cannot be patented. Economic concerns include: claim locations, dummy locators, common variety nature, "excess reserves," and environmental constraints. Also, geologic and mineralogic studies, sampling and testing procedures are vital. Mining, milling, processing cost, and taxes must be evaluated. Product marketability analysis is necessary before starting any cash flow or discounted cash flow study. Valid data is essential to evaluate an economic industrial mineral deposit.

Jan 1, 1997

By R. G. Swanton

The Bureau of Mines is investigating the leaching of phosphate values from Florida phosphatic clay wastes using sulfuric acid (H2SO4) as the leaching agent and methanol as the solvent. Acid-alcohol leaching studies were done using pure crystalline apatite to investigate potential causes for low extractions. It was found that a barrier layer formed on the surface of the apatite. Initial discovery of the barrier layer was made by analyzing pure apatite samples before and after leaching using an optical microscope. Subsequent Fourier Transform Infrared (FT-IR) analyses proved the coating was calcium sulfate hemihydrate (CaSO4-1/2H2O) and that unreacted apatite existed beneath the coating. Scanning electron microscope (SEM) photographs depict the CaSO4-1/2H2O morphology as long slender crystals adhering to the apatite surface. It was also shown that grinding the leached tailings and leaching again in the H2SO4-methanol system resulted in additional phosphate extraction.

Jan 1, 1991

By Douglas M. Deason

Swelling clays, such as montmorillonite, contribute significantly to the poor dewatering and consolidation behavior of the Florida phosphate clay wastes. Understanding and to a degree, control of the forces which cause the swelling behavior may aid in supplying a solution to this problem. The technical feasibility of utilizing control- led dispersion for aiding dewatering of phosphatic slimes was investigated. This technique is based upon inhibition of swelling and self-dispersing tendencies of the montmorillonite clays by dispersing the solids in electrolyte solutions. Through this process, significant improvements in settling rates and sediment solids content were achieved in both pure clay systems and on simulated phosphate slimes.

Jan 1, 1983

By T. J. Malterer

Peat has unique physical, chemical, and biological properties. These include high porosity and water retention, high absorption and adsorption properties, high buffering capacity, and it is a rich medium for microorganism activity. Peat has traditionally been used for horticultural purposes. However, in recent years, peat is increasingly being used for waste treatment purposes. This paper reviews North American literature on the use of peat for waste treatment applications. The literature indicates promising use of peat in treating municipal and on-site effluent, removal of low concentrations of heavy metals from wastewaters, and adsorption of liquid and gaseous hydrocarbon pollutants.

Jan 1, 1995

By Mark Cadzow, Rodney Lamb

CARBAD is a recently developed Australian process for the recovery of gold and platinum group metals (PGM). The process relies on the selective agglomeration phenomena of the gold and PGM to capture the mineral in a carbon-hydrocarbon media. The precious minerals are then extracted from the loaded media by a solvent gold room process producing a relatively pure concentrate. The media is then reformed and recycled. The process development from batch test work to a 5 t/h commercial scale CARBAD plant is discussed. The operation and results of processing a variety of ore types at several alluvial and hardrock gold mines is examined. The operating and capital costs for the CARBAD process shows that it is significantly less than that the conventional CIP/CIL. The environmental safety of the process is a major feature where precious metal deposits are located within urban environments or within wilderness areas.

Jan 1, 1989

By R. W. Mossman, George E. Heim

Seismic exploration techniques offer the engineer and geologist a way of obtaining detailed information on the physical parameters and geometry of the rocks where extensive underground excavation or tunneling is proposed. Use of the seismic method can provide a greater amount of detailed information at relatively less cost than can be obtained by any other known subsurface exploration method. Boreholes are still required for calibration of the seismic data but at a much wider geographic spacing than otherwise would be needed for subsurface mapping. The seismic data can define with precision the actual location of zones of flexure or fracture of the rocks and reveal the configuration of the surface of the rock layers. ENGINEERING PROBLEMS One of the major requirements in the planning of subsurface installations is that of locating tunnels and other underground openings in favorable rock units. Such rock units should exhibit uniformity of composition, both vertically and horizontally, to minimize variation in excavation techniques. The depth and thickness of the unit must be known: a 30-foot diameter tunnel cannot be contained in a 25-foot thick limestone. The rock unit needs to be as free as possible from structural defects and should be suited to efficient excavation procedures. If liquid conduits are planned, the slope of the rock unit needs to be known so that maximum advantage can be taken of gravity flow with the tunnels wholly contained within the unit.

Jan 1, 1997

By I. E. Odom

A study was made of the physical and chemical nature of silica minerals found as natural impurities in bentonites and montmorillonitic Fuller&apos;s earth clay products as well as in <10 micron dust from eight processing plants. The results show that the silica minerals present in these clay materials are totally encapsulated or encased in clay. No "free" silica minerals could be observed in SEM images of either granular or powder products or in dust samples collected for MSHA crystalline silica analysis. Silica minerals, such as quartz, are identifiable by SEM and EDS analysis only after removing the clay coatings by vigorous washing. After washing it can be observed that all crystalline quartz grains also have diagenetic overgrowths of what is probably opaline silica. The clay and opaline silica encapsulation of quartz plus the strongly hydro scopic nature of montmorillonite are believed to be responsible for there not being a single confirmed case of silicosis among workers in the subject plants after more than 65 years of production.

Jan 1, 1996

By Daniel T. Brian, O&apos

Exploration targets and results in the mining industry are commonly summarized in terms of tonnage and grade. Business appraisals require, as additional information, the expected profit or loss implied by the physical summary. The early incorporation of knowledge gained through financial analysis computations can provide a means for economically resolving many common exploration and development problems. Examples of such applications from the activities of exploration planning, reconnaissance, land acquisition, and development planning are presented in this paper.

Jan 1, 1969

By Debra Switzer, Swapnil Urankar, Douglas Watson, Steven Hunter, Chandranth Banerjee, Shashank Pathak

A hydrocyclone is a piece of equipment commonly used as a classifier in mill circuit operations. Traditionally, hydrocyclone performance is characterized by the classification efficiency parameter, such as cut size (d50c), sharpness of separation () and bypass (Rf ). A plethora of endeavors have already been made to develop parametric models to determine hydrocyclone performance that correlate design and process variables. In contrast to those studies, we made an attempt to develop an approach to derive required design parameters purely from hydrodynamic principles that provides a platform to optimize the operation of a hydrocyclone for a given application. In this selection methodology, we calculated the differential pressure at the air core, as well as the tangential velocity at the boundary of the air core from the vortex principle in a confined geometry at different operating regimes. A series of experiments were conducted using Weir’s Cavex® hydrocylone where process variables—such as solids concentration and feed flowrates—were experimentally studied to determine the key classification parameters. For the validation of the current approach we used the same process variables to derive design parameters and compared them with the existing design. The current approach can provide insights towards the selection of design parameters and can be useful for mining industry professionals to optimize different operating parameters of hydrocyclones to achieve the best performance.

Feb 1, 2024

By Steve Kral

"Each January, tunneling and underground professionals gather in New York City for the George A. Fox Conference. The one-day event offers attendees the opportunity to listen to their peers outline what’s new in the underground construction industry, get updates on major projects in North America and have a chance to catch up of old friends.The conference is put on by the Underground Construction Association of SME. This latest conference attracted about 370 specialists in the industry. The theme for this year’s event was “Water Tunnels, Past, Present and Future.”The technical session included talks focused on major tunneling projects, including the massive California Water Fix program and the Massachusetts Water Resources Authority (MWRA) Metropolitan tunnel redundance program in Boston. The conference also included an update on the Gateway Project from Phil Rice from WSP and Mahammed Nasim of Amtrak as well as a Tunnel Industry update.The following is a sample of a few of the presentations. Technical presentationsDEP’s Tunneling Program Evolution. James Mueller is the agency chief engineer of New York City’s Department of Environmental Protection (DEP). Its mission is to plan sustainable infrastructure investments for the future of clean water and the environment in the city and its watersheds, he said. The agency’s goals are to synthesize information across bureaus within DEP to allow data-driven decision-making. It is also to optimize internal agency processes and systems related to the implmenation of engineering programs within a structured assessment process. The agency also prioritizes projects and funding within a structured integrated planning process. And it standardizes project performance and delivery to meet the needs of the agency in alignment with industry standards and market capabilities."

Mar 1, 2019

By W. E. Lindquist

Roasting of refractory gold ores has the primary goal of oxidizing sulfides and organics to improve gold recoveries prior to leaching. Commercial installations currently utilize bubbling and circulating fluidized beds. The principle of flash roasting is aimed at a more cost effective method of whole ore roasting for large throughput applications. Results of pilot plant testing and scale up to commercial design will be discussed in further detail in this paper.

Jan 1, 1993

By John G. Groppo, Bonnie Webb-Groppo

INTRODUCTION The first portion of this chapter is concerned primarily with the contamination aspects of fine coal cleaning that include both the solids and water discharged as waste products after coal preparation. Topics include characteristics of the water and solids, changes that occur to both of these phases during use and after impoundment, as well as the impact that these changes have on unit operations and the environment. Attention is also given to the formation of acid mine drainage and treatment options that may facilitate reuse of the water. The second part of the chapter analyzes the problem of air contaminants from coal preparation plants including analysis of air pollutants and control methods. An overview of air quality regulations is also presented; most provisions have little or no applicability to coal preparation plant operation but are presented to provide an understanding of end-user constraints. The final part of the chapter emphasizes the long-range problem of refuse disposal and control. An overview of characterization, maintenance, and control of the refuse area is presented, as well as design guidelines. A brief review of stability analysis procedures is also included. PREPARATION PLANT WATER Characteristics of Makeup Water for Coal Preparation There are few specific rules governing the quality of makeup water used in coal preparation processes.&apos;" It is generally accepted, however, that the solid matter content should be less than 5%. The solids concentration in plant makeup water typically varies between 0.25 to 0.9 lb per gal (30 to 110 g/L) and may reach concentrations as high as 1.7 lb per gal (200 g/L). The water used in coal preparation is usually obtained from one or more of the following sources: public supplies, rivers and streams, canals, mine water, and wells. In most cases, water is obtained at the lowest cost including any necessary treatment. A major portion of the recirculated water is clarified by thickeners and settling ponds to remove fine coal and clay particles. Sufficient water is generally available to meet the needs of coal preparation in most areas. It has been estimated that approximately 65 to 70% of the makeup water used in a coal preparation plant comes from surface sources. It is important to note that a variety of substances are commonly found in natural water supplies, whatever the available source may be (Table 11-1). Excessive concentrations of some of those substances can have an affect on plant performance; the effect of specific contaminants on unit operations will be discussed

Jan 1, 1991

By R. Q. Honaker

Although the fundamental principles of hindered bed classifiers are relatively simple, the complex interactions between the operating parameters provide a degree of difficulty that hinders the ability for on-line plant optimization. Thus, a dynamic population balance model was developed for determining the hindered settling velocity of particles varying in density and size. The steady-state results of the model include partition curves as a function of particle size and density as well as metallurgical data. A statistical comparison of the simulation results with those obtained from industrial units reveal a high level of accuracy with adjusted R2 values greater than 0.95.

Jan 1, 1999

By George K. Martin

This paper deals primarily with roof bolting in Kentucky coal mines from January 1, 1949, through December 31, 1954, a six year period. The Consolidation Coal Co? (Ky.), a division of the Pittsburgh Consolidation Coal Co., began systemmatic roof bolting in November 1948 in Mine #204, Elkhorn #3 Seam, at Jenkins, Kentucky, After the efficiency of roof bolting had been proven by the Consolidation Coal Co., this procedure was adopted by other companies throughout the state. In December 1954, approximately 46.4 percent of Kentucky&apos;s total production of coal from underground mines was obtained from roof-bolted areas. Statistics in this report will show the progress made in roof bolting during the six years, in addition to the roof bolting being done as of December 31, 1955. Significant progress has been made in the coal mines of Kentucky in reducing the roof-fall fatality, rates, during the past several years by adopting systemmatic roof bolting. The ground work by the Consolidation Coal Co, (Ky.) in cooperation with the Federal Bureau of Mines was based upon the previous experience of the St. Joseph Lead. Cc, in its Southeastern Missouri Mines and The Tennessee Coal and Iron Division of the United States Steel Corporation. The author gratefully acknowledges the cooperation and assistance given by officials of the various mining firms using roof bolts, the Kentucky Department of Mines and Minerals, and the Federal Bureau of Mines in furnishing photographs and information.

Jan 1, 1958

By H. Polat

Relatively large amounts of such hydrocarbons as fuel oils are often needed in flotation of low rank coals. The amount of oil can be decreased considerably by using surfactants as promotors. The reagents which are good candidates as surfactants to promote hydrophobicity can also act as emulsifying and wetting agents. Since the physical and chemical variables influence various sub-processes in different ways, their influence on the performance parameters is complex. The results of laboratory tests are presented to show that the dual role of reagents can be judiciously exploited to increase both the recovery and grade of clean coal. The mode and order of reagent addition is critical in enhancing their efficacy as flotation promotors. The results demonstrate the benefits of proper conditioning of the pulp prior to flotation.

Jan 1, 1997

By Thomas H. Dubaniewicz

(XP) enclosures to enclose electrical ignition sources to prevent propagation of an internal methane-air explosion to a surrounding explosive atmosphere. Researchers at the National Institute for Occupational Safety and Health (NIOSH) conducted a lithium-ion battery thermal runaway test within a modified MSHA-approved XP enclosure to assess thermal runaway containment. Thermal runaway produced jet flames emanating from the cover joint at several locations and distorted the cover joint and bottom plate of the enclosure beyond allowable limits. The test demonstrates that XP enclosures may not provide adequate explosion protection against lithium-ion battery thermal runaway. This paper suggests some approaches to mitigate the hazard.

Feb 1, 2024