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By R. Asmatulu

According to Darcy?s law, the rate of filtration should increase with increasing pressure drop across a filter cake. In centrifugal filtration, the driving pressure is created by the centrifugal forces applied in the free water on the surface of a filter cake. However, the pressure drop can become negative when the free water surface disappears, which makes it difficult to achieve low cake moistures. In hyperbaric centrifugal filtration, this problem is overcome using air pressure to restore the pressure differential. In the present work, various mineral and coal fines have been subjected to hyperbaric centrifugal filtration tests. The laboratory tests show that the moistures of various mineral fines, such as copper and zinc concentrates, phosphate, talc, kaolin clay, and precipitated calcium carbonate, can be reduced substantially below that achieved by conventional centrifuges. Similar promising results have also been obtained with various coal fines in laboratory and pilot-scale test programs and in full-scale plant demonstrations.

Jan 1, 2012

By R. T. Swinderman

This paper discusses how many of the common practices in conveyor specification and design are out of date compared to the current expectations of users for safe, serviceable, reliable, and fugitive material-free conveyance of bulk solids. Ten of the most common mistakes made in the specification and design stages related to user expectations are reviewed along with the cost vs. price implications of those decisions. A general specification and design hierarchy that designers can use to improve conveyor design is included.

Jan 1, 2010

By Thomas R. Kuesel, Harvey W. Parker

INTRODUCTION This paper describes the use of a shield and compressed air for construction of a short section of a pair of twin single-track tunnels for the Metropolitan Atlanta Rapid Transit Authority (MARTA) transit system. Although only two blocks long, this section posed the greatest difficulties to both engineers and contractors, and is the most expensive section of line construction on the MARTA system. All this derives directly from its setting--these tunnels had to be constructed through mixed-face conditions. SETTING The Broad Street tunnels form a link between the Peachtree Center and Five Points Stations, in the heart of Atlanta's central business district (Figure 1). Peachtree Center sits atop a solid rock ridge, which inspired the design of a deep rock-mined station, as described in the 1979 RETC. Five Points Station is MARTA's hub--the intersection of the system's two main branches. It is located in the old railroad gulch, a filled-in erosional valley at the base of Peachtree Ridge, and was constructed by open-cut methods. The alignment and profile of the Broad Street tunnels were closely constrained by these two adjacent anchors, and in the six-block stretch between them there was very little room for maneuvering. Since the rock ridge petered out about in the middle of the section, it was evident at the outset that there would be about two blocks of rock tunneling at the north end, two blocks of soft ground construction at the south, and two blocks of mixed-face in between. It is this central two-block section that is the focus of this paper.

Jan 1, 1981

By A. A. Terchick

In 1970 U. S. Steel acquired the physical assets of mine, mine property, and preparation plant of the Crystal Block Coal Company near Thacker, Mingo County, West Virginia. The facility, identified as U. S. Steel Mine No. 20, is administered and operated as a production unit of U. S. Steel Gary District, Gary, West Virginia. Mining operations of the No. 20 mine are conducted in the high-volatile Alma seam. The preparation plant, which originally had a capacity of about 150 tons per hour (tph) of raw-coal feed, had process circuitry consisting of a Daniels heavy-media vessel for cleaning the plus-1/4-inch raw coal, a McNally-Pittsburg feldspar jig for cleaning the 1/4 inch by 28 mesh, and Daniels flotation cells for treating the 28 mesh by 0. No water-classification system existed. Refuse tailings from the plant were pumped to several surface lagoons which were decanted to the stream. The settled solids were removed and trucked to the coarse-refuse disposal area. Water make-up requirements were supplied by a small mine-water surface reservoir and augmented with stream water. Expansion of production from the property required an increase in preparation-plant raw-coal-feed rate capacity from

Jan 1, 1974

By Jerry R. Johanson

Introduction Many solids processes that look feasible on paper or even in pilot studies become disasters in full scale. Changes in solids flow characteristics from pilot scale to full scale be- cause of larger solids contact pressures, thermal shocks, or unforeseen temperature excursions often cause full-scale solids flow problems not encountered in the laboratory or pilot studies. Fortunately, proper applications of solids flow principals and solids flow properties measurement at full scale conditions can anticipate the problems and thus provide an accurate basis for full-scale design or existing plant modifications. Solids flow properties The basic solids flow property definitions are given in Table 1 (Johanson, 1966, 1976, 1978, 1985). In this section, the author will discuss each property and its potential for creating full-scale pilot plants. Unconfined yield strength The unconfined yield strength of a bulk solid determines the tendency for cohesive hangups of the solids in the process and is effected by the time at rest, chemical reactions, temperature, liquid content, solids size consist, and phase changes of solids or fluids involved in the process. One of the common mistakes is to consider the solids condition only at the beginning and the end of the process. For example, consider the direct reduction of iron ore. The feed solids are free-flowing, hard lump ore or pellets. The end result is a hard, free-flowing reduced sponge iron lump or pellet. One might conclude that the process involves free-flowing lumps. This conclusion may seem reasonable based on laboratory studies oreven pilot plant studies where solids contact pressures are very low. Unfortunately, during the reduction reactions at high temperatures, the rock or pellets soften and, with solids contact pressures associated with the full-scale plant, may fuse together, thus providing a possible solids hangup in the moving bed reactor not evident in the low pressure pilot scale. Fig. 1 shows some typical unconfined yield strength measurements for pellets as a function of solids contact pressure at various times at rest. Note at low consolidation pressures, generally associated with laboratory or pilot plant studies, the pellets show no strength unless held at rest for an extended time. This will produce a very free-flowing condition in pilot plants that will not exist in the full size reactor.

Jan 1, 1990

By Felicia F. Peng

The naturally occurring aged manganese oxide coated on the granular media was found to have a catalytic effect on the removal of low concentration of Mn(II) (-1 ppm) from drinking water. Applying this principle, a manganese removal technique was developed for removal of higher concentration of Mn(II) (-100 ppm) from mine drainage by using various aged filter media and synthesized granular media with manganese oxide coatings. Laboratory-scale continuous granular media column experiments were conducted to assess the feasibility of manganese oxide-coated granular media for Mn(II) removal from synthesized mine drainage. The removals of Mn(II) were evaluated as a function of operation parameters including solution pH, manganese oxide concentration coated on the media, interstitial velocity, and oxidant concentration of influent. Higher solution pH and/or higher manganese oxide concentration promoted the removal of Mn(II) on the oxide-coated granular media under low interstitial velocity. Addition of sodium hypochlorite as an oxidant in the influent resulted in continuously regenerated oxidized surface to serve as the catalyst for Mn(II) oxidation reaction on the surface of oxide-coated media.

Jan 1, 1994

By C. Newman, N. Schaefer

"As underground mining continues to operate at deeper depths and in more complex geologic and geometric conditions, there has been an increased demand for mine designs to better reflect site-specific conditions, measurements, and observations with respect to ground control safety and stability. During the past 20 years, the National Institute for Occupational Safety and Health (NIOSH) has developed, validated and distributed a number of free software packages (ALPS, ARMPS, AMSS, ARBS, etc.) specifically aimed at providing the industry with ground control design tools for the evaluation of underground stability in coal mines. While these programs were initially developed as stand-alone software packages where all data reside on an individual or workgroup computer, modern day web applications have begun to migrate toward a “multiple-tier” architecture, allowing multiple users to access an application by means of an Internet connection.This article introduces a new Web-based platform for ground control software applications, webGroundControl (webGC). webGC provides users with a platform through which one can access NIOSH and other ground control design software utilizing a Webbased, multiple-tier architecture. This provides users with easy access to ground control designs, the ability to perform on-demand calculations, as well as increase online collaboration between operational personnel and engineers through a web server. The basic framework and, more specifically, the user-interface of webGC are defined and outlined within this paper. It is expected that the mining industry will rapidly embrace this new product and webGroundControl will be a new paradigm for mining engineering computer applications. Platform architectureAs Web-based computing technologies continue to advance and cloud computing gains momentum, web-based platforms for software applications are growing in popularity across all industries due to ease of product accessibility and distribution as well as data security. With the expansion of Internet connectivity on the surface and underground, there is an industry need to develop Internet-based applications for mine and ground control design (Barczak et al., 2016). Cloud-based products are already available for many industries and are slowly being developed for the mining and geotechnical industry. A notable example is the drillysis package, which is a cloud-based borehole logging database (Geosysta, 2017) or the Dynonobel package for on the fly blasting calculations (Dyno Nobel, 2013)."

Jan 10, 2017

By John W. Tieman

The increasing magnitude of our nation's pollution problems seems to stem from two main factors: urbanization and technical advance. In 1920, less than half the country's 106 million people lived in cities. Forty years later, the urban population accounted for 70 percent of the nation's 179 million. It is predicted that by the end of the century, 95 percent of the U. S. population, estimated at 280 million, will live in urban areas. As these people live increasingly in city concentrations, their residues also concentrate. With technological advances to support the increasing population, the variety and quantity of goods that we use also increases. New materials and processes result in increases in pollutants, some of them new. The harmfulness of these pollutants is sometimes known, but sometimes only suspected. One pollutant of concern at the present time is sulfur dioxide, the product of combustion of sulfur-containing fuels. Research on processes to remove sulfur oxides from flue gas has been in progress for many years. Pioneers in this field were the British who, in the early 1930's, installed a full-scale flue gas scrubbing unit on a 120 MW boiler using alkaline water from a Thames estuary plus chalk. Since that time, various methods have been studied by many investigators. Federal laws covering air pollution started with the 1955 Air Pollution Control Act. With the advent of the Air Quality Act of 1967, and subsequent publishing of criteria and available technology for control of sulfur oxides in January 1969, the clamor for information on commercially available control techniques to remove sulfur from fossil fuels has rapidly increased. Although many state-of-the-art papers have deluged the literature during the past several years, the research going on in the area of sulfur oxides control is of such importance that periodic reviews are justified. It is the purpose of this paper, therefore, to again review the state-of-the-art, but this time from the stand-point of what is immediately commercially available

Jan 1, 1972

Jan 1, 1999

By R. L. Atwood

The structure, properties, and composition of commercial chelating-type copper extractants are examined. Characterization of these extractants was accomplished using organic separation techniques and analytical tools such as NMR and IR. Results indicate that only the trans isomer of the diphenylhydroxyoxime (LIX (R) 64N) is capable of copper chelation. The effect of the structural modification of the extractants on the extraction and stripping reactions are discussed.

Jan 1, 1972

By Lawrence Tsang, Conrad Ng, Tim Leung, Peter Poon

"The Mined Tunnel is part of the Central-Wan Chai Bypass and Island Eastern Corridor Link (CWB), which is a strategic road along the northshore of Hong Kong Island targeted to alleviate the heavy traffic congestion. The objective of this paper is to review the performance of construction of a 160m long Mined Tunnel with a trinocular cross-section area of 460m3 and a combined span of about 50m underneath the southern approach ramp of the existing Cross Harbour Tunnel (CHT) by sequential excavation method (SEM) in hard rock. Mechanical excavation of tunnel by adopting the New Austrian Tunnelling Method (NATM), together with the application of NGI Q-system allows observational approach and optimization of temporary rock support design. Furthermore, the good performance of optimized rock support and the stability of CHT are confirmed through instrumentation monitoring review. This paper also discusses the selection of different tunnel plant and equipment to achieve the planned rates of tunnelling by mechanical excavation in competent granitic rock. INTRODUCTION The works of the CWB mainly comprise construction of 4.5km dual three-lane trunk road, of which a 3.7km section is a tunnel connecting Rumsey Street Flyover in Central to Island Eastern Corridor at North Point (see Figure 1). The Mined Tunnel runs from the ex-Public Cargo Working Area (ex-PCWA), underneath the existing CHT, and through the Causeway Bay Typhoon Shelter. The Mined Tunnel passes at an oblique angle beneath the southern portal of CHT over a length of some 50m. CHT is the primary sensitive receiver of this project and is utilized with a daily throughput of about 120,000 vehicles that far exceeds the design capacity of 78,000 vehicles per day. Hence it is necessary to choose the most appropriate tunnelling method to preserve the structural integrity of the CHT. Other sensitive receivers in the vicinity include structures to the north of the Mined Tunnel, the Royal Hong Kong Yacht Club (RHKYC); and to the south of the Mined Tunnel, the Police Officers’ Club (POC)."

Jan 1, 2016

By Jack O?Hearn

A liquid and solid waste management plan for an operating uranium ore processing mill was developed to efficiently and effectively dispose of existing solid wastes and related, affected surface and ground water resources. The goal of this management plan was to achieve satisfactory clean up of these existing wastes ad their by-products as well as to prevent similar situations from occurring in the future. An existing, modern system of synthetically lined tailings ponds, constructed after many years of mill operations, now provides an approved site for the disposal and containment of waste streams currently generated by the mill. This system was thought to be readily adaptable to serve as a key element of the waste management plan. The potential presence of extra capacity in these ponds could eliminate or reduce expenditures for new facilities required solely for proper management of liquid and solid wastes generated by operations prior to construction of the modern tailings ponds as well as for a range of anticipated future operations.

Jan 1, 1984

By Thomas Novak, Philip Johnson, Richard L. Sanford, Lloyd A. Morley

Macintosh use in mine-planning applications lags DOS machines since many users have made significant investments in hardware and training for other environments. Macintosh use is becoming more pronounced in many other industries, and com soft-ware is of at least the quality of that available for DOS machines and many workstations. This paper describes attributes of the Macintosh computer family as related to many mine-planning problems and solutions including software, memory considerations, workstations, DOS compatibility, and networking.

Jan 1, 1993

By Paul J. Henkels

Synthetic gypsum is the calcium sulfate co-product of a number of industrial processes. Synthetic gypsum utilization as an alternative to the naturally occurring mineral continues to grow in the gypsum industry. In particular, flue gas desulfurization (FGD) gypsum produced by the electrical utility industry has had a significant impact and a far-reaching effect on the gypsum wallboard manufacturing industry. This paper will discuss the various synthetic gypsum sources verses natural gypsum and highlight issues of use in gypsum wallboard and related products.

Jan 1, 1999

By Andy Thompson, Frank Perrone

"As part of the Metropolitan Transportation Authority’s $10.5bn East Side Access Project in New York, 3,200 m of tunnel had to be constructed in rock, mix face and soft ground conditions beneath one of the largest passenger railroad junctions in North America, handling over 780 trains per day. The use of risk based decision making tools was essential in developing the bespoke contract framework that was adopted as well as making informed decisions once excavation commenced. This paper will outline the risk management process adopted, discuss the risks and mitigation strategies adopted and comment on the impacts of this approach on the as built Project cost and schedule. In particular, the paper will outline the unique approach used to establish the baseline against which the Contractors performance would be measured as the selection of a Slurry TBM to excavate the tunnels was considered to compromise the effective use of a Geotechnical Baseline Report. BACKGROUND AND CHALLENGES Contract CQ031, Queens bored Tunnels and Structures was awarded in September 2009 to a joint venture of Granite Northeast/Traylor Brothers/Frontier Kemper (GTF JV) for $717.6m following a negotiated procurement process. A robust approach was taken with regard to the management and payment for risks associated with the construction of these tunnels. Risk assessments were carried out during the design phase and a risk register was developed prior to procurement. During the procurement phase close attention was paid to ensuring that the allocation and pricing of known risks, together with mechanisms for managing future risks were clearly defined between the MTA and GTF JV.In comparison to the excavation work in Manhattan, which was performed in competent hard Manhattan schist, the tunnels in Queens were excavated predominantly through soft ground with a high water table and complex environmental conditions. Not only did this require the use of pressurized face TBM technology, a first in New York, but also a re-evaluation of the contractual mechanisms used to manage the hard rock excavation contracts for their appropriateness to the soft ground tunnel work."

Jan 1, 2016

By W. –E. Marx, M. Faber, R. Pollak, I. Astberg

INTRODUCTION Essentially three strategies are pursued in parallel for protecting the underground working force in mining against the consequences of methane ignitions which might lead to explosions: • Sufficient ventilation for avoiding the formation of explosive methane-air mixtures. • Avoiding sources of ignition caused possibly by electrical equipment or friction. • Structural explosion protection for limiting explosion propagation to the farthest-going extent for the case that methane is fired because of failing of the above preventive measures taken. The corresponding methods taken in mechanized roadheadings with point-attack roadheaders in German coalmining are subject of this paper. VENTILATION In ventilation of roadheading sites the following is to be considered in respect of methane control: • Sufficient air flows by volume being cycled to the heading face for diluting released methane to safe concentrations. • Sufficient local air velocities for effective mixing of methane and air in the whole heading site, in particular directly on the heading face and underneath the roof. Furthermore, ventilation needs to be laid out in a way that cut- ting does not result in health affecting dust exposure at any working place. Accordingly, the ventilation systems shown on Fig. 1 including primary and, if necessary, secondary auxiliary ventilation air ducts as well as dedusters, are used in roadheadings. This equipment is run according to the following principles: • If the roadheader is at standstill, the heading face is ventilated by the free air jet from the blowing duct closest to the face. In this operation phase the deduster is shut-down. • During cutting, the exhaust of the blowing air duct is automatically closed, and the deduster is taken into operation. The in- coming fresh air is now locally discharged via a lateral orifice, or distributed by Coanda-type ducts from the primary or secondary ventilation air duct. In this way, a stable dust wall not disturbed by the jet of the air duct is formed in front of the heading face. Only the ventilation air stream taken in by suction of the close-to-face deduster is passed through the inby zone of the heading face (over approx. 20 m). The clean exhaust of the deduster is dischayed to the roadway in some distance outby. Immediately at the heading face, methane accumulations possibly released by cutting are diluted by compressed-air jets from air-movers located near the roof which assure more rapid motion of the air without distuhing the dust wall. • In the zone of overlapping of primary and secondary duct and the deduster - that zone possibly is poorly ventilated during cutting - sufficient local air speed is assured by Coanda-type ducts or additional ventilation jets for avoiding methane accumulation. The regulations of the inspectorate specifies geometrical conditions to be met with these configurations of ventilation equipment. In-seam roadways are ventilated at rates > 0,5 m/s. For dedusters, present-day ventilation air flows are of 600-800 m+/ min. Ventilation monitoring and control is assured by units for measuring methane and ventilation air flows. If pre-set thresholds are exceeded or fallen short of, these measuring units shut-down - dependent on potential hazard - any not intrinsically safe electrical equipment in the roadheading, either totally or in limited zones. In addition, CO-measuring units near the roadway en- trance serve for early detection of mine fires. In spite of this ventilation layout and the equipment used and in spite of the water spray systems on the cutting head (discussed later in this paper) several cases of methane ignition and subsequent burning off (however, no explosions) have been recorded in the recent past. Therefore, the above-described ventilation is nowadays complemented in many cases by machine-mounted ventilation equipment for the immediate surroundings of the cutting head. Ventilation of the surroundings of the cutting head Investigations carried out subsequent to the above-mentioned gas ignitions have shown that the high ventilation air speed necessary for rapid dilution of methane could not permanently be arrived at in the following zones: • The direct zone of cutting, in particular during sumping. • The floor zone above the debris, predominantly below the cut- ting head. Accordingly, VOEST ALPINE-Bergtechnik, a producer of mining machinery, in cooperation with DMT developed for point- alttack roadheaders a novel machine-mounted ventilation equipment, the Jet-Block" (AERO SAFE Jet-Block) shown on Fig. 2. This system allows to ventilate the above-mentioned critical zones with high flow speeds. One AS Jet-Block is mounted on each side of the boom approx. 0.5 m behind the cutting head. The blocks discharge compressed-air jets with high energy from 10 nozzles per block into the hazardous zones (Fig. 3). Two nozzles of each jet block are tangentially oriented toward the upper circumference of the cutting head, the others are arranged fan-like with orientation to the heading face underneath the cutting head and the debris. The nozzle array of the blocks as well as the com-

Jan 1, 1997

By L. Yuan, C. Brown, N. Rayyan, J. Soles, T. H. Dubaniewicz

As lithium-ion batteries (LIBs) become more prevalent in the mining industry, new hazards of battery fire and explosion are emerging. Efforts must be taken to ensure that workers are safe from these new hazards, such as batteries undergoing thermal runaway in underground areas that may have explosive methane-air mixtures. Researchers at the National Institute for Occupational Safety and Health (NIOSH) investigated overpressures generated within a sealed battery enclosure filled with an explosive methane-air mixture and a single cell lithium-ion battery driven into thermal runaway using an accelerating rate calorimeter (ARC). For both iron phosphate (LFP) and nickel manganese cobalt (NMC) lithium-ion cells, the explosion overpressures remained unchanged with varying percentages of methane concentration in the atmosphere surrounding the cell. It’s likely that the gases released from the battery undergoing thermal runaway caused an inert atmosphere within the sealed canister. The results from this study will help mining equipment manufacturers develop proper measures to keep miners safe while working with lithium-ion batteries in underground gassy mines

Mar 2, 2022

By C. K. C. K. Gupta

The rare earths in elemental form are required for a variety of scientific and technological purposes. They are not easily obtained in this form, due to the great chemical stability of the rare-earth compounds and the strong tendency of elemental metals to react with everything they come in to contact with, especially at high temperatures. Beginning in the 1950s, when sufficient quantities of separated rare earths became available, as the result of intense research and development, three processing routes were developed to accomplish the preparation of all 16 naturally occurring rare-earth elements. They are chemical reduction of the halide intermediates, the oxides and electrochemical reduction of chlorides and oxide-fluoride mixtures. Not all the processes are effective with all the rare earths. In spite of the celebrated similarity of trivalent rare earths, the physical properties of individual rare-earth elements are sufficiently different that a variety of techniques are required for their preparation. The development of reduction processes for the rare-earth metals are covered in this paper, with focus on the oxide reduction routes. The strong reliance of effective reduction processes on the fundamental science of reduction reactions is highlighted.

By V. F. Swanson

A mathematical model for free and hindered settling of minerals was developed. This paper describes how to apply the model in designing systems, such as fluidized bed, elutriation, mixing pumping systems, involving solids and fluids.

Jan 1, 2000

By W. J. Maloney, H. E. Tuneblom, A. J. Smith

The development of a large regional water supply in Southern West Virginia faced several hurdles. This paper deals with the design and construction of the intake shaft where a combination of cutting edge mechanical excavation technologies were utilized to produce a world class project.

Jan 1, 1999