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By R. Wisniewski

Every underground coal mine in the United States must deploy and operate a wireless communication and tracking system. This paper addresses the reliability and availability of an installed tracking system and the communications infrastructure that supports it. A particular interest is the requirements for the systems to operate continuously without failure after a mine disaster for 96 hours, and the requirements in the MINER Act for the tracking systems to be ?calculated to be serviceable? and the communications systems ?redundancy?. These requirements imply a certain reliability and availability. This paper describes a quantitative way to assess these systems requirements, using the tools that are available and commonly used by the Reliability, Maintainability, & Availability community.

Feb 23, 2014

By F. Shigeyoshi

The development of pelletizing during the last ten years has continued, however, self-fluxing pellets have not been regularly and commercially produced for use in blast furnaces, except as Kobe Steel, Ltd., Japan. This paper tells about unique developments for self-fluxing pellets, and their effects when used in Kobe Steel's No. 3 blast furnace at the Nadahama Works (inner volume 1845 Nm3, hearth diameter 9.5 m)., Several phases of the pelletizing process are discussed individually, and also their relation to performance in blast furnace operation. Special emphasis is placed on proper preparation of the limestone added to the raw materials, and indurating at optimum conditions. Means of improving pellet quality by correct control of size distribution of the raw materials used in pelletizing, and indurating temperatures, are also discussed. As basicity (CaO/SiO2) of pellets increased 0. 1, coke consumption decreased 3. 8 to 4. 2 kg per ton of hot metal, when using 70% pellets in the iron burden.

Jan 1, 1969

"Mine ventilation is in every underground mine a crucial process to ensure mine safety as well as acceptable working conditions. On the other hand is also a major cost factor depending on air requirement and air resistance. Due to the fact that the special layout of mines develop over time, ventilation systems change as well. This may result in complex systems which are suffering severe problems and low efficiency. With attention to the mine safety and costs, ventilation systems have to be controlled repeatedly and optimized continuously to fit changing conditions. The project “Improvement of ventilation systems in narrow vein mines” has been commenced with measuring and data collection in the Bogala Mine, Sri Lanka. This over 150 year’s old graphite mine consists of about 20 levels. The resulting ventilation system is highly complex and suffers problems like high temperatures and humidity as well as a mixing of fresh and used air on lower levels. To solve these problems and to optimize the system the complete ventilation system had been measured on-site first. The gained data have been used for simulations to develop and select an optimal and cost efficient solution. OBJECTIVE As an important process in mining ventilation is a major cost factor and can determine the economic feasibility of a mine. Due to the production mine layouts develop over time and mines increase in size and depth while the ventilation system becomes more complex and may suffer severe problems and inefficiency. Therefore mine ventilation systems have to be controlled and optimized regarding the general requirement of mine safety and health of the miners as well as the costs. Depending on the deposit type, depth, mining method, climate and as well corresponding laws and regulations the possible solutions are varying strongly. The work carried out paid special attention to the improvement of ventilation in narrow vein mines in tropical climate, in this case the graphite mine “Bogala” in Sri Lanka, South Asia."

Jan 1, 2015

By Robert C. Bates

Published information discussing uranium mine radon daughter controls and related costs was examined and used to develop an estimated (projected) cost per ton for any level of control. Results show a clear power function increase of cost for conventional dilution ventilation as the annual exposure limit is lowered. Projections can be made using any assumed changes in consumer price index (CPI) and radon daughter working level months exposure limit. Bounds on the estimated costs are provided, and applicability of the final equation is discussed.

Jan 1, 1983

By Jon Y. Kaneshiro, Eric Dawson, Pooyan Asadollahi, Steven Hunt

This paper provides updates to the paper published by the lead author at RETC 2011 with a summary of developments in technologies, products, and approaches to corrosion analyses of gravity sewer tunnels and microtunnels. This paper presents approaches in evaluating degradation of reinforced concrete liners. Also, the carbon footprint of conventional concrete liners and alternative “green” liners are compared and their life cycle costs are considered. A few case histories from the past decade are provided indicating the latest and emerging trends in liner protection.

Jun 13, 2023

By M. F. Werneke

Flotation of the carbonate, oxide and silicate minerals of copper (malachite, azurite, chrysocolla) has been the subject of much research in recent years, but few effective solutions to this problem have been found. With decreasing reserves of sulfide minerals, the economic recovery of these "oxides" appears to be an important source of copper for the future. Xanthates have been known for many years to be malachite collectors (1), but only at very high dosages, or at lower dosages following activation of the mineral by sulfide ion. Dewitt and Batchelder (2, 3) found that chelating agents such as certain oximes were collectors for malachite and azurite, but also required high reagent dosages. Fuerstenau (4) has suggested, for example, that potassium octylhydroxamate may be an effective collector for malachite, On the other hand, Balberyszski (5) has found that oxide minerals may be completely sulfidized at high temperatures with gaseous sulfur or H2S, and then floated with conventional collectors. None of the above approaches appear to offer an economically effective method for the direct flotation of these oxide minerals.

Jan 1, 1977

By J. C. Stankus

Many coal seams are associated with soft floor strata and during mine development if coal pillars are not properly designed, floor heave occurs and causes interruption of coal production. In the severe cases, the section or mine is abandoned. One of the methods for controlling floor heave is floor bolting. This paper describes the demonstration of floor bolting methods in a West Virginia coal mine. Three methods were used: (1) vertical full resin bolting, (2) floor truss bolting, and (3) floor truss bolting plus a floor cut at the center of the entry. The design of each method and the experimental results are discussed in detail.

Jan 1, 1993

By Robert S. Shoemaker

The development of a metallurgical project is a business venture rather than a technical exercise, and its real objective is to obtain the maximum return on investment consistent with the limitations imposed by company policy and the requirements of society. Demand for profits is the driving force for technical advances and naturally leads to improvements in processes, equipment and plant designs. In the mineral dressing field there have been virtually no new processes developed since the introduction of flotation, and the steady erosion of profits by inflation has been offset only by increasing equipment size. Unfortunately, in recent years, plant designers have not always utilized the largest equipment or the opportunities for functional and economic design presented by the development of larger equipment. Lower cost plants can be developed providing that unrealistic restraints arising from the prejudice of past practices are avoided. As an illustration of this premise, three different approaches were taken toward the design of a clearly delineated but hypothetical copper concentrator of 20, 000 tons per day capacity. While the same flowsheet was used in each case, designs were produced for a conventional plant, an alternate using the largest available equipment, and a third scheme utilizing large equipment and the most functional design which could be developed, including features derived from many plants in many different industries. Capital costs were developed for the three separate designs based on a location in the southwestern United States. Ancillary facilities were identical in each case and included a mine truck shop, a maintenance shop, a general office, and a nominal starter dam for tailings disposal within 5000 feet of the plant. Water supply within 1000 feet of the plant, and power furnished to the property boundary has been assumed in each case. The flowsheet of the three plants is shown in Figure 1 and represents the treatment of a typical sulfide copper ore by three- stage crushing followed by single-stage ball milling. Concentration is by flotation roughing and scavenging followed by regrinding of the concentrates and two stages of cleaning.

Jan 1, 1971

By Yakup Cebeci, Leyla Kalender, Ceylan Yarluğkal Altınışık, Hikmet Sis

The abstract highlights the challenges in concentrating complex and non-sulfide lead-zinc ores and emphasizes the importance of froth flotation for their beneficiation. The study focuses on using process mineralogy to understand the flotation behavior of these ores from the Görgü region. The ore samples were characterized using various techniques, revealing oxidation and carbonation of primary minerals. The flotation results were interpreted in light of the mineralogical data, explaining the poor outcomes due to the complex nature of the ore, poor liberation, and lack of hydrophobicity.

Mar 22, 2022

By Bryant Fitch

This paper will review thickening theory, from the ( ) of the practicing engineer, with particular emphasis on ( ) uncertainty or disagreement. It will attempt to outline broadly what we know and what we don't know. This should serve two purpose First, it will warn the process engineer where he might get into trouble. At least it will alert him to the risk involved in uncritically accepting any of the recommended design procedures. Second, it will identify for researchers some areas in which further work might be fruitful. Not too many years ago there would have been little to write on such a subject. We had been designing thickeners for decades, using the classic Coe and Clevenger procedure. As far as we were generally aware, they all turned out to be about the right size. And so if there was anything we didn't know, It certainly wasn't hurting us much. Today we know better. While it is true that in most cases units designed by the Coe and Clevenger procedure (1) will perform satisfactorily, we now know of cases in which they don't. And during the past few years there have been many developments and advances in basic thickening theory. So there is now a lot more room for disagreement, and a whole lot more to be uncertain about. What is "thickening" "Thickening" means different things to different people. For this paper we define it to mean sedimentation behavior characterized by line settling. Solids subside with a clear line of demarcation between settling solids and supernatant. Although the supernatant will usually be clear, in some cases it may be turbid. Line settling must entail that all particles just below the pulp-supernatant interface have the same subsidence rate, so that

Jan 1, 1971

By Yi Yang, CHENGLONG XU, HAORAN LI, YALI FENG, JINRONG JU

This study presents a method for recovering valuable metals and synthesizing anhydrite from steel slag using sulfuric acid leaching and solvent extraction. The process achieved high leaching efficiencies for V, Ti, Fe, and Mg, and produced anhydrite with 93.09% purity. The leachate was further processed to separate and recover V, Ti, Fe, and Mg using selective stripping and precipitation methods, offering a sustainable approach to steel slag utilization.

Jan 22, 2022

By M. Rîsteiu

The authors aim to analyze the behavior of smart sensors using Transmission Control Protocol/Internet Protocol (TCP/IP) infrastructure in hazardous applications, because of their advantages regarding safety, expansion and Quality of Service (QoS). Initially, some constraints are discussed for these applications. Then, the possibility is analyzed of using 2.4 GHz TCP/IP based transmission for sending data out of an industrial area. In this setup the authors evaluated the round-trip implementation (which requires a database of packet lengths), related to the delay introduced by the radio transmission algorithms from 802.15.4, and 802.11d/g protocols. Tuning results of different varying time-delays were compared to the constant delay cases from the literature (Deák, 2003; Lincoln, 2003). Both the hardware and software setups are implemented. Based on TinyOS specific software for hardware checking/ initiating communication/ starting/ closing measurements the authors have developed separate/combined procedures for testing the integrated devices. Measured time delay is presented and analyzed, for both beaconed and non-beaconed 802.15.4 transmission, with power optimization criteria. By testing two different implementations (Zhang et al., 2001), (ATmega256 RZAV - 256KB flash memory, the CC2420 IEEE 802.15.4 and ZigBee-compliant RF transceiver core - 128KB flash memory) the authors have found some time delay variations as a result of local processing by the ZigBee controller with an amount of flash memory. The work is also focused on adapting industrial measuring standard systems to the smart sensors, but not only through the 4-20 mA standard.

Jan 1, 2008

By Toby Mayo, Tassos Grammatikopoulos, Massoud Aghamirian, MARK FEDIKOW

The Zoro pegmatite project in east-central Manitoba occurs 20 km east of the historic mining town of Snow Lake. A composite sample (Master Comp) was prepared fromthree pegmatite zones within Zoro Dyke “D1” including the North, Central, and South Zones for mineralogical analysis and heavy liquid separation (HLS). The mineralogical examination was conducted on a subsample crushed to ca. P80 of 600 μm to determine the overall mineral assemblage, liberation of spodumene, and assess the potential recovery of spodumene by flotation. XRD and QEMSCAN results show that the sample consists of spodumene (10.5%), quartz (29.3%), plagioclase (29.0%), K-feldspars (21.3%), micas (5.1%), tourmaline (2.9%), and Fe-Mn-phosphates (0.1%). Spodumene is well liberated (88%), but also forms complex particles (7%), and middlings with quartz (4%). Liberation of spodumene increases from 81 in the + 600 μm to 95%in the − 106 μm size fraction. Liberation of quartz, feldspars, and micas account for 89%, 94%, and 83%, respectively. Electron probe micro-analyses and LA-ICP-MS showed that the average Li concentration is 3.7% in spodumene, 2196 ppm in micas, 1001 ppm in tourmaline, and 115 ppm in K-feldspars. Thus, spodumene accounts for 96%, micas 2%, Fe-Mn phosphates 1%, and both K-feldspars and tourmaline for < 1% of the total Li in the sample. The mineralogical data indicate the potential to recover spodumene by flotation with minimal Li losses due to other than spodumene carriers. Heavy liquid separation was conducted on the Master Comp which was crushed to − 6.4 mm, while the − 600 μmfractionwas removed fromthis test. The coarse fraction − 6.4mm/+ 600 μmwas subjected to HLS tests with eight heavy liquid-specific gravity cut-points (2.65 to 3.10 g/cm3). HLS indicates that it is possible to produce a high-grade lithium concentrate (close to 6% Li2O) after the rejection of iron silicates with magnetic separation.

Sep 16, 2020

By Lloyd B. Underwood

In the event of a sudden nuclear attack upon the United States, it is imperative that vital command and control centers have a high probability of survival. One such vital facility is the North American Air Defense Command Combat Operations Center at Colorado Springs, Colorado. Known briefly as NOW, this installation when completed will be housed in large chambers excavated out of granite beneath the eastern slope of Cheyenne Mountain (Figure 1). The NORAD COC, a U. S. Air Force sponsored project, will serve as the primary collection and evaluation center for data concerning unknown aircraft, missiles, or space vehicles, which might bring destruction to North America. The data will be fed into high-speed computers and electronic equipment from outpost sources - radar, ballistic missile early warning stations and picket ships throughout the world. Electronically controlled display boards will make it possible to evaluate the tracking data instantaneously and to take appropriate defensive action1.

Jan 1, 1965

By P. R. Dugan

Sulfur removal from high sulfur coal has several objectives including: a) reduction of the atmospheric load that contributes to the problem of acid precipitation; b) reduction of ash, which contributes to decreased energy transfer in boilers, as well as ash disposal; and c) alleviation of the social and economic dislocations related to uneven geographical distribution of sulfur in coal reserves. Cost in relation to the value of refined coal will govern the development of an emerging coal refining industry. Estimation of the premium paid by power companies for coal with a low sulfur content is a good estimate of the value that will be added as the result of refining. Estimates of premiums paid in 1984 are $28.65/t ($26 per st) for reduction of total sulfur from 370 to 1% S and greater than $28.65/t ($26 per st) for removal below 170 sulfur.

Jan 1, 1988

By N. C. Saxena, S. K. Puri, A. K. Pal

The condition-based monitoring system is an important innovation for reducing the downtime of costly, heavy earth- moving machinery (HEMM). Vibration severity measurements were made on the HEMM located at the Gevra Project, the largest coal opencast project in India. Whenever the vibration severity levels exceeded the permissible limits, necessary actions were taken to replace the defective parts of the ma- chine. The systematic vibration monitoring of 120-t (132-st) dumpers, followed by corrective measures led to a substantial increase in component life (8.18% for an 445E Dressor and 28.44% for an MK-30 Unit Rig). The associated costs (including spareparts) were reduced by 21.55% and 25.74%, respectively. Because of the reduced downtime, savings for these two dumpers over the period from March 26 to June 25,1998, were of the order of Rs.26.47 (US$0.649) million.

Jan 1, 2000

By Thomas F. Evans

Niagara Mohawk, like other northern coal users, has long experienced increased costs during winter months as a consequence of handling frozen coal. These costs include operating labor, maintenance labor and materials, equipment rental, fuel for thawing, demurrage, carrying costs for excess coal inventory and substitution of higher cost electrical generation for lost production capacity. In the winter of 1978-79, limited trials of several coal freeze conditioning agents were made to determine whether these would provide a cost-effective means of reducing the problems of handling frozen coal. Since these trials were generally effective, the Coal Purchasing Department arranged that all rail coal received during the 1979-80 winter from early December to mid March would be treated at the mines during loading. Inasmuch as the treatment costs are themselves appreciable and our various coal suppliers made a variety of choices of chemical supplier and equipment for application, an attempt was made to evaluate the unloading performance of each train received at the two generating stations which use coal as an aid in the future optimization of the use of freeze conditioning agents. These stations also receive coal by truck but this coal is not treated because of the short hauling time. The C.R. Huntley Station in Tonawanda, NY has a capacity of 800MW and burns about 5000 tons of coal per day during the winter months. The coal is primarily from central and western Pennsylvania but one source in southern Kentucky is also used regularly. Most of the Pennsylvania coal is washed and the fines are thermally dried. The coal is delivered in unit trains made up of mixed cars of 60, 75, and 90 ton capacity. Time between loading and arrival at the station averaged five days and ranged from three to eleven during the 1979-80 winter season.

Jan 1, 1980

By J. Paraszczak

Application of teleoperated and automated (or ?autonomous?) mobile equipment in underground metal mines is a promising avenue for overcoming some of the challenges facing mine operators. These include, but are not limited to, the issues related to safety and health of underground workers, better use of the shift time leading to increased productivity, skilled manpower shortages, and remoteness of some mine sites. Autonomous load-haul-dump machines and trucks offer several benefits over man-operated ones, but their use at their full capacity is a challenging and complex task. This paper makes an overview of commercially available equipment and systems and their applications. It examines factors affecting adversely availability, utilization, and production efficiency of autonomous vehicles and compares them to conventional man-operated machines. Technical and operational aspects are discussed and their criticality is analyzed. Based on that, recommendations concerning means and measures that may help raise operational effectiveness are given. It is stressed that due to a scarcity of publicly available information on the performance and cost of autonomous loading and haulage operations, more field studies and in-depth analysis are needed.

Feb 23, 2014

By Andrzej M. Wala

A knowledge of the friction factor (K-factor) is necessary in planning and designing mine ventilation systems for least cost and highest effectiveness. The friction factor used must be accurate and reliable for correct estimation of airway resistances. At present, the friction factors are determined by using tables of published values. These values were established principally for metal-mine openings having small effective areas. This presents a problem to the ventilation design engineer whose responsibilities center around the design of effective ventilation systems for large room-and- pillar mechanized underground coal mines. Friction factors selected from these tables could be excessively conservative for large scale room-and- pillar operations. With only limited data on the K-factor (which are considerably site dependent) for Kentucky&apos;s coal mines and for all the above mentioned reasons, it was concluded that there is a need for field investigations to determine these values in-situ for existing mining conditions in Kentucky. The author describe the study carried out in ten coal mines located in eastern and western Kentucky and present the results of the investigation in both tabular and graphical form.

Jan 1, 1991

By J. R. Goode

The first part of this paper comprises a general discussion on refractory gold ores and their mineralogy processing methods now in use are reviewed and test procedures for the important methods are discussed. Factors determining the selection of a process are outlined. The paper includes a survey of production plants using pressure oxidation, roasting and biological oxidation to process refractory ore. The status of processes under development is briefly reviewed.

Jan 1, 1993