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Edwin H. MessiteR, New Pork City (communication to the Secretary*):—Under the heading " Flues," Mr. Edwards refers to the Bee-hive construction, a cross-section of which is shown in Fig. 4 of his paper. A flue similar to this was designed by me about six years ago,' in which the walls though much thinner than those described by Mr. Edwards gave entire satisfaction. These walls, from 2.25 in. thick throughout in the smaller flues, to 3.25 in. in the larger, were built by plastering the cement mortar on expanded-metal lath without the use of any forms, or cribs, whatever, at a cost of labor generally less then $1 per sq. yd. of wall. Of course, where plasterers cannot be obtained on reasonable terms, the cement can be molded between wooden forms, though it is difficult to see how it can be done with an interior core only as stated by Mr. Edwards. In regard to the effect of sulphur dioxide and furnace-gases on the cement, I have found that, in certain cases, this is a matter which must be given very careful attention. Where there is sufficient heat to prevent the existence of condensed moisture inside of the flue, there is apparently no action whatever on the cement, but if the concrete is wet, it is rapidly affected by these gases. At points near the furnaces there is generally sufficient heat not only to prevent internal condensation of the aqueous vapor always present in the gases, but also to evaporate water from rain or snow falling on the outside of the flue. Further along, a point is reached where rain-water will percolate through minute cracks caused by expansion and contraction, and reach the interior, even though internal condensation does not occur there in dry weather. From this point to the end of the flue the roof must be coated on the outside with asphalt paint or other impervious material. In very long flues a point may be reached where moisture will condense on the inside of the malls in cold weather. From this point to

Jan 1, 1905

By Geraldine Woods

I work for the State of Washington as an Explosives inspector. My paper will describe the mission of the Wa. State Dept. of Labor pertaining to explosives and the regulation of explosives in the State.Blasting safety is high on the public safety list and the regulation of explosive use and storage has been mandated through legislature. The Dept. considers pro-active partnering forexplosive safety preferable to after-the-fact citations for non-compliance.In some cases, the Dept. will issue civil citations with monetary penalties, meant to be a deterrant, of course, to blasters who choose not to comply with the explosive regulations of the State.The Dept. has also revoked and suspended blasting licenses. In some instances, the Dept. has allowed recipients of citations with monetary penalties to reduce the amount paid by attending technical training classes. The idea here, is to reduce the chance of reoccurence of unsafe blasting practices. The State of Washington partners with MSHA in the regulation of explosives use and storage in mines, pits and quarries in the Stateas well as working closely with law enforcement, State and local fire marshals, ATF,and is active in ISEE in part of it’s ongoing effort to promote explosive safety and establish communications in a nonadversarial way with explosives users. My paper will include some statistics on licensing in the State, pounds of explosives used, inspection numbers, numbers and types of complaints with information from the inspections resulting of these complaints. My paper will include examples of storage, both good and bad, examples and pictures of fly rock incidents, accidents, near-miss close calls, break-ins, thefts, and abandoned explosives. This paper may also include a brief summary of my opinion of explosive regulation and my job as a regulator, including examples of high and low points of the job, joys and frustrations.

Jan 1, 2002

This paper addresses the valuation and development timing of an undeveloped mineral project. Traditional analysis has us developing the project immediately if its net present value (NPV) is positive. Option pricing theory finds that it is better to wait until the NPV of the property is significantly greater than zero before developing. Alternatively, when evaluating the development timing decision, we must calculate NPV using a higher "timing-adjusted" discount rate, and develop the property only if its NPV using this timing-adjusted discount rate is greater than zero. This paper uses option pricing ideas to convert this development timing advice into a more concrete and user-friendly decision rule: develop the project when its "development-timing NPV" is positive, this development-timing NPV being calculated using the normal discount rate.

Jan 1, 1997

By A. R. T. Denues

"INTRODUCTION The Explosives Division of the Bureau of Mines, United States Department of the Interior, is investigating cushioned blasting at the Explosives Testing Station, Bruceton, Pa. The general interests of this investigation are practical and relate particularly to safety. The immediate concern is an application of cushioned blasting in coal mining.In cushioned blasting, various means are employed to reduce the intensity of the application of energy in an explosive action in a borehole. The primary object is to increase the efficiency of the use of explosives. Cushioned blasting is designed to save the energy usually lost in excessive shattering and in this way to effect economies and to produce increased proportions of desirable lump coal. That this saving should lead to greater efficiency is indicated by an analogy with the theory and experience of size-redaction by crushing or grinding from which it is known that a large proportion of the energy consumed is expended in producing the smaller sizes (26),3/. Aside from these considerations, increasing the yield of lump coal is important in practice because larger sizes of coal usually sell at higher prices. Some statistics published in England in 1934 (63) illustrate the economic origin of the interest in increasing yields of lump coal; these indicate for three sizes of coal that as the size decreases the value decreases in the approximate series 3:1.5:1, thus:"

May 1, 1940

By G. R. Guillet

THE LATE Dr. D. F. Hewitt, Ontario's foremost authority on industrial minerals, was the first to point out the importance of urban minerals when he produced figures (Hewitt 1968) to prove that the Toronto-Hamilton area was Ontario's second largest mining camp in 1966 (Fig . 1). In that year, the value of mineral production within a 60-mile radius of downtown Toronto exceeded individually that of Steep Rock, Kirkland Lake, Timmins, Manitouwadge and Elliott Lake. Only the nickel and precious-metal production of Sudbury .surpassed in value that of Toronto's pits and quarries. Although that position was unchanged for some years during the early sixties, it was admittedly an unusual situation: gold was still pegged at an artificially low value; uranium was stagnant; and Texasgulf had not entered the scene. However, the point had dramatically been made. The combined value of production from hundreds of sand and gravel pits and dozens of limestone and shale quarries was of formidable proportions. The mining industry of the urban fringe could not be denied. Construction aggregates, cement, building stone and bricks were fueling an apparently insatiable appetite for urban expansion and redevelopment.

Jan 1, 1978

The Earth?s population is approaching 6.6 billion people. More than half live in urban areas. And, as those figures continue to grow, the need to make wise use of the world?s natural resources as well as its living space will also grow. Thus, the concept of sustainable development ? meeting the needs of the current generation while preserving resources for future generations. The use of underground space is only one part of the sustainable development concept. But it is an important one. Tunnels and underground space are environmentally friendly and contribute significantly to sustainable development. But it takes years to plan and build tunnels and other underground infrastructure. And the demand for infrastructure in the world?s mega cities has grown significantly. In December, about 100 people representing several developed and developing nations spent a day at the United Nations (UN) in New York City discussing the future of underground space development throughout the world. The meeting was put on by the UN?s Department of Economic and Social Affairs and the International Tunnelling and Underground Space Association (ITA). The conference was titled ?The Use of Underground Space as an Unexpected Solution for Promoting Sustainable Development.? Its aim was to promote practical solutions to the use of underground space and tunnels as feasible alternatives to promote sustainable development throughout the world. A panel of speakers from government, academia, the UN and the ITA stressed that development is not sustainable without infrastructure. And, as the world?s population grows, there is now an urgent requirement to efficiently plan for the use of underground space to preserve it for the future benefit of mankind. The benefits of the use of underground space are many, they said. Among them: ? Tunnels channel clean water in and waste water out. This promotes health and sustainability worldwide, particularly in developing countries. ? The use of tunnels and underground space helps conserve energy and increases its efficient use ? the use of tunnels cuts commuting time and so saves energy. ? Tunnels, microtunnels and other underground structures promote the more efficient use of space in large cities ? the bulk storage of water, fuel and other goods. ? Underground structures are subject to less stress than surface structures, making them safe havens for natural and man-made hazards, including earthquakes. And, because underground structures are more durable, lifecycle costs are less than surface structures. ? Underground structures promote the multiple use of available land. Land owner-ship at several layers increases land use and provides more usable space. Han Admiraal is director of the Center for Underground Construction in the Netherlands. He said that urban planners need a new vision concerning the use of underground space. Going underground protects historical and archaeological surface facilities, he said. Underground space use can also protect populations located in adverse climates. And sensitive environmental areas on the surface can also be protected from development. In addition to the transportation of people, freight and water, underground development can also store water, as well as provide storage for waste, hazardous materials, carbon dioxide and geothermal energy. The upshot of this new awareness and vision for under-ground space is that its use should be considered before surface development, Admiraal said. And planners and developers are placing more emphasis on underground space development as part of their overall development plans for urban areas. That was not always the case, he said. In the past, underground space was not considered until after the surface space had run out, he said.

Jan 1, 2008

By B. DANIEL MARJAVAARA, I. A. SOFIA LARSSON, ANNA-LENA LJUNG

The flow field and coal combustion process in a pilot-scale iron ore pelletizing kiln is simulated using a computational fluid dynamics (CFD) model. The objective of the work is to investigate how the thermal effects from the flame affect the flow field. As expected, the combustion process with the resulting temperature rise and volume expansion leads to an increase of the velocity in the kiln. Apart from that, the overall flow field looks similar regardless of whether combustion is present or not. The flow field though affects the combustion process by controlling the mixing rates of fuel and air, governing the flame propagation. This shows the importance of correctly predicting the flow field in this type of kiln, with a large amount of process gas circulating, in order to optimize the combustion process. The results also justify the use of down-scaled, geometrically similar, water models to investigate kiln aerodynamics in general and mixing properties in particular. Even if the heat release from the flame is neglected, valuable conclusions regarding the flow field can still be drawn.

Apr 20, 2021

By Bernard J. Steblay

Millions of mechanical anchor roof bolts are used each year for mine structural support. The benefit of this bolting depends on a number of factors including rock density, bolt length, in situ stresses, time elapsed between mining and installation, rock properties, bolt patterns, and tension (Lang, et al., 1979). Installation tension is a major determinant of support quality. Postinstallation tensions indicate both the usefulness of the individual bolts and the behavior of the reinforced rock structure. The importance of short- and long-term bolt tension measurements is well recognized, and such measurements are required by regulations (Fed. M/NM Nine Safety and Health Reg.). These regulations also take into account the difficulty of practical tension measurements. Only a statistical sample of the bolts installed is required to be measured using current torque wrench technology. Drawbacks to this practice are that the anchorage is disturbed and perhaps weakened, accuracy is limited by friction to about 30% (Lang, et al, 1979, and Barry, et al., 1956), and the procedure is relatively time intensive.

Jan 1, 1984

The purpose of this study is to develop designs to facilitate and accelerate auger rotation stoppage (and auger rotation start up so as to promote auger disengagement during auger miner repositioning) and to provide a time delay and warning signal prior to auger start up to permit any miner s near the augers to get away from the augers before they start rotating. In the underground coal mines in the U.S., there are four auger miners that are currently in use. They are the Jeffrey 100L (see Figure 1-1) and 100M (see Figure 1-2), and the Wilcox WCM and the MK20A (see Figure 1-3).

Jan 1, 1974

By Ronald Althouse

During the past five years under contract with the U. S. Bureau of Mines (BOM Contract J0308002). West Virginia University's Mining Extension Service (WVU-MES) has designed, developed) and delivered to the mining industry a comprehensive training program for Mine Rescue (MR) teams and a management planning tool for Mine Emergency Preparedness. The Mine Rescue team program is systematically built on a set of training objectives, backed up by content, allowing mine operators to conduct team training activities. These materials are user-ready, provide the MR principles and practices for both initial and advanced training, and supply teams with exercises geared to problem-solving activities. In addition to an instructor's program guide, the eight (8) modules that comprise the initial (20 hour) MR training are: an Introduction to Mine Rescue, an Introduction to Self-Contained Breathing Apparatus (SCBA), a set of modules covering each approved minimum 2-hour SCBA (i.e.) the Draeger BO 174-A. the McCaa) the Aerolox. & the Scott Rescue-Pak), and a manual on Auxiliary Apparatus as well as the Chemox Auxiliary SCBA. Advanced, annual refresher training (40 hour) is covered by seven (7) modules that spell-out the principles and practices needed to establish surface organization, to handle mine gases as well as mine ventilation, to conduct exploration, for fires, firefighting, and explosions, to rescue survivors and recover bodies, and to accomplish a mine recovery. Approved by MSHA in 1984 to meet requirements for 30 CFO. Part 49, these materials provide a basis for trainers' instruction, for comparison of team capabilities, for modifying programs resources, and services, and for program planning. The Mine Emergency Preparedness Program (MEPP) is used by management as a tool in the preparation of company personnel for handling a mine emergency operation. As a wholly new program. MEPP depends upon development of a Mine Emergency Organization and Emergency Operations Procedures. It also requires regular scheduling of drills) periodic mock emergencies, and evaluation of organizational responses and program performance beyond required training of mine rescue teams. MEPP materials are arranged into three sets of guides: 1) the Preparedness Program System Guides include an Executive Summary, a Program Director's Guide Mine Emergency Organization, and Emergency Operations Procedures; 2) the Emergency Organization (MEO) User's Guides cover the Rescue and Advisory Division, the Technical/Safeguarding Division, and the Surface Support Division; and 3) the Emergency Procedures (EOPS) User's Guides detail Containment Level Procedures, Notification Level Procedures. Mobilization Level Procedures, and Deployment Level Procedures.

Jan 1, 1986

By B. J. Vorster

The South African Iron and Steel Company Ltd operates a large Iron Ore Mine in the Cape Province of the Republic of South Africa. The Mine is situated on the farm, Sishen, approximately 600 km west of Johannesburg. The annual capacity of the Mine is 100 million ton of ore and waste and the present production level is 60 million ton. The Mine operates continuously for 6 days a week. The primary equipment used to maintain the above production are 55, 154 t trucks (Wabco and Unit Rig) and 14 P & H shovels. During 1979 an urgent feasibility study into the application of a trolley assist system was launched at the Mine. This was due to the unrealistic escalation in the cost of diesel fuel and the appeal from the South African Government to reduce the use of fossil fuels. Tests and economic evaluations proved the system technical feasible. The estimated discounted cash flow return exceeded 50% and the diesel fuel consumption would be reduced by 120 million litres in the next 10 years. Management subsequently approved the implementation of the system at Sishen. The construction of 7,7 km of line and the conversion of 66, 154 t trucks were completed in March 1982.

Jan 1, 1985

By G. Nazari

ERAMET, through its subsidiary COMILOG, have rights to a rich niobium and rare earth deposit inGabon. The Mabounié deposit, is located 50 kmfromthe town of Lambaréné, in a fairly remote location. ERAMET has been developing a process to recover value metals for several years, and approached Hatch Ltd. to design a sizeable Demonstration Plant to help them further optimize the process, and prove the flowsheet is technically viable. The process employs concentration techniques to recover an upgraded Nb/REE feed material for processing in the subsequent leach step. Rare earths and niobium are selectively leached, and subsequently precipitated. Following precipitation, rare earths undergo bulk separation and are purified to produce LRE and mixed MRE/HRE products, which will be further processed by Third Parties. This paper provides a high-level overview of the process, summarizes the motivation for a Demonstration Plant in the vicinity of the deposit, and discusses technical challenges faced during the flowsheet definition and design phase. Key challenges are focused on and summaries of the methodologies used to address each challenge, as well as the solutions to overcome the challenges, are discussed. The paper provides motivation for further process simplification and concludes with a project update.

By Gustavo Huerta Valer, Jorge Cárdenas Miranda, Johan Salas Flores

One of the challenges of mining is the optimization of the blasting process, which has an important impact downstream in the processing of crushed ore in the plant, that is why mining companies ensure the results of granulometry obtained from the blasting process through a joint work with companies specialized in the process of loading with explosives.

Feb 6, 2023

By I. Campbell, P. C. Jones, E. G. Potter, R. P. Taylor

"The Cobalt embayment is a large domain of Paleoproterozoic clastic sedimentary rocks that unconformably overlies the Archean Abitibi greenstone belt. Regionally extensive sills and dikes of Nipissing diabase, emplaced circa 2219 Ma, occur throughout the embayment and are the preferential host to gold-bearing polymetallic vein systems on the Merico-Ethel property, near the northeastern margin of the Cobalt embayment. These gold-bearing, polymetallic veins are predominantly east-west-trending, steeply dipping, discordant calcite- quartz vein systems that formed close to the time of crystallization (within ~15 m.y., based on Pb-Pb ages) of the Nipissing diabase. The ore mineralogy is complex in character, typically comprising sulfides, arsenides, native metals (gold and silver), and specular hematite, preferentially concentrated along the interface between silicate and calcite gangue. A simplified sequence of mineral deposition in the veins is: (1) "Early-stage" pyrite ± chalcopyrite hosted in quartz ± chlorite gangue; (2) "Main-stage" polymetallic (Cu + Co + As + Ag + Au + Bi ± Pb ± Ni ± U) sulfides, arsenides, and native metals hosted in calcite gangue; and (3) "Late-stage" calcite flooding ± galena. Wall-rock alteration in Nipissing diabase is restricted to narrow (<5 cm) haloes of calcite-chloriteepidote- bearing assemblages, whereas a weak alteration halo of specular hematite, calcite, and allanite-epidote has been observed in the surrounding sedimentary rocks. In terms of their age, geology, mineralogy, paragenesis, and morphology, the gold-bearing vein systems at Merico-Ethel closely resemble the silver-sulfarsenide vein deposits of the historic Cobalt and Gowganda mining camps. These observations indicate that the Au-bearing veins are variants of the Ag-vein systems and as such, have a common genesis belt. L’Échancrure de Cobalt est un large domaine de roches sédimentaires clastiques d’âge Paléoprotérozoïque qui reposent en discordance sur la ceinture de roches vertes d’Abitibi d’âge Archéen. La Diabase de Nipissing, mise en place vers 2219 Ma et qui constitue un réseau de sills et de dykes d’importance régionale, est présente dans l’ensemble de l’échancrure et constitue la roche-hôte principale des systèmes de veines aurifères-polymétalliques de la propriété Merico-Ethel, près de la bordure nord-est de l’Échancrure de Cobalt. Ces veines à minéralisation aurifère et polymétallique constituent un système de veines de calcite-quartz sécantes d’orientation principalement est-ouest et à pendage fort qui se sont formées peu de temps après la cristallisation de la Diabase de Nipissing (à ~15 Ma près, d’après les âges Pb-Pb). La minéralogie de la minéralisation est complexe; elle consiste typiquement en sulfures, en arséniures, en métaux natifs (or et argent) et en hématite spéculaire, préférentiellement concentrés à l’interface entre les silicates et la gangue de calcite. La séquence de déposition simplifiée des minéraux dans les veines est : (1) «Stade précoce» pyrite ± chalcopyrite encaissés dans une gangue de quartz ± chlorite; (2) "Stade principal" sulfures polymétalliques (Cu + Co + As + Ag + Au + Bi ± Pb ± Ni ± U), arséniures, et métaux natifs dans une gangue de calcite; et (3) "Stade tardif" calcite massive ± galène. L’altération pénétrative de la Diabase de Nipissing est confinée à des halos étroits (<5 cm) présentant des assemblages marquées par la présence de calcite-chlorite-épidote, tandis qu’un faible halo d’altération en hématite spéculaire, calcite et en allanite-épidote est noté dans les roches sédimentaires environnantes. De par leur âge, leur géologie, leur minéralogie leur paragenèse et leur morphologie, les systèmes de veines aurifères de Merico-Ethel ressemblent beaucoup aux gîtes filoniens d’argent-sulfoarséniures des camps miniers historiques de Cobalt et de Gowganda. Ces observations indiquent que ces veines aurifères constituent une variante des systèmes des veines argentifères et qu’elles partagent"

Jan 1, 2009

By C. E. Wicks, F. E. Block, F. D. Stevenson

The vapor pressures of tungsten (VI ) chloride ( WC1 ) and hafnium ( IV ) iodide ( HFI ) were measured by a metal diaphragm technique . Vapor pressure values were obtained to permit calculation of the thermodynamic properties of the vaporization processes of the compounds . The vapor pressure data of WC16 are represented by the following equations for the liquid , B - solid , and a- solid over the temperature intervals indicated : - log P = 8.194 3,253 /T Liquid , 281.5 ° to 325 ° C : B - solid 230.0 ° to 281.5 ° C : log P a - solid 185.0 ° to 230.0 ° C : log Pam *** = 8.794 - 3,588 / T = 9.615 - 3,996 /T where T is the absolute temperature in degrees Kelvin . The heats of vaporization and sublimation are 14.9 , 16.4 , and 18.3 kcal / g mole , respectively . The entropy of vaporization at the normal boiling point , 330 ° C , was 24.3 eu . The fusion temperature , 281.5 ° C , and transition temperatures , 230.0 ° and 185 ° C , were found by thermal analysis .

Jan 1, 1964

By Jorge Ganoza

Dado que la metalurgia no es una ciencia nueva -en tanto que los conceptos utiilizados como propiedades geológicas, mineralización, procedimientos de extracción y recuperación de oro son practicados durante mucho tiempo, la variación actual de su nombre, no es determinante. En ese sentido, el presente texto señala algunos aspectos metalúrgicos del oro como: mineralogía de los depósitos de oro, las muestras geometalúrgicas para el programa de pruebas, mezclas de minerales, ley de oro y relaves de cianuración.

May 1, 2013

By George R. Elliott

Introduction The pages that follow present a brief chronological survey of views which have been held, and of legislation enacted, for the regulation of the natural gas and oil industry in the Turner Valley field, especially as regards conservation of the natural gas. To provide a necessary background for an adequate understanding of the progress of events in western Canada, there is included also a compilation, from technical and legal authorities, of some of the more important measures which have been adopted for the regulation of the oil and gas fields of the United States, where these measures have had, or are likely to have, a bearing on the course of our domestic industry. Owing to exigencies of space, it has been possible to refer only to the most outstanding proposals and legislation, and to these in the briefest possible form. Although, so far as Canada is concerned, the data presented are restricted almost entirely to the Turner Valley field, it is the hope of the writer that the paper may prove of value for purposes of reference: for any similar gas and oil fields discovered in western Canada will certainly revive and intensify the problem of the proper steps to be taken for the conservation of the gas. Definition of &apos;Conservation The term conservation has been so misunderstood and misrepresented that, to many persons in Alberta, it means little more than closing-in wells. In the light of the definition of Charles E. Hughes, that &apos;True conservation of a raw material is its economical use&apos;, the subject of natural gas conservation is inseparably involved with the study of the function of the -gas and with the development of the principles of unit operation.

Jan 1, 1934

By James Noll

Total carbon (TC) is sometimes used to measure or characterize diesel particulate matter (DPM) in occupational settings such as underground mines. DPM samples are collected on quartz fiber filters. When using quartz fiber ?lters, adsorption of gas phase organic carbon (OC) has been reported, causing a positive bias in the particulate TC results (adsorption artifact). Most of the data on the sampling artifacts and corrections apply to environmental air sampling, where samples are collected at a much higher filter face velocity and the OC concentrations are generally much lower relative to occupational sampling. In this study, we investigated the effects of adsorption artifact on samples from occupational settings. Samples were collected with and without denuders to determine the amount of gas phase OC collected and the accuracy of certain corrections. In underground stone mines, the adsorption artifact was found to positively bias the particulate TC by greater than 20% for filter loadings below 25 µg/cm2 TC (8-h time weighted average) 262 µg/m3). The tandem ?lter correction reduced the effect of the artifact, as high as 60% of the TC value, to less than 11% for laboratory data. It also significantly reduced the effect of the artifact obtained for field samples.

Jan 1, 2008

By E. Shum, V. G. Papangelakis

"Attempts to reduce the energy requirements of water recovery in the process industries have resulted in the development of techniques to freeze and purify aqueous solutions that take advantage of local climatic conditions. Natural freezing is a technique by which aqueous solution is exposed to freezing air temperatures, resulting in the production of a layer of ice on the surface. As the ice layer tends to exclude solute, a concentrated solution is formed. However, due to dendritic ice growth along the advancing growth front, small quantities of solution are trapped within the ice, decreasing the purity of the water recovered. The ice produced can then be allowed to thaw in order to recover the water using low grade plant heat. As the more concentrated parts of the ice melt first, a purer ice remains. In this study, 0.5 molal magnesium sulfate solution was frozen under simulated natural freezing conditions at temperatures between –1 and –6°C. The ice produced was thawed at either room temperature or 50°C. Up to 40% of the water was recovered with a separation efficiency of above 95% when thawing at room temperature.INTRODUCTION Advances in refrigeration technology have made low-temperature separation processes increasingly appealing to an energy-conscious society. The latent heat of freezing of water is about seven times smaller than the latent heat of evaporation providing freezing with a strong thermodynamic advantage over the traditional evaporation-based processes. The result is the development of a wide variety of processes that fall under the term Freeze Concentration (FC), which describes a variety of techniques in which an aqueous solution is concentrated by the creation and subsequent removal of ice (Williams et al., 2015).FC processes exploit the freezing behaviour of aqueous solutions as dictated by their respective water-salt phase diagram. When, for example, a solution of magnesium sulfate is cooled to a temperature below its freezing point but above its eutectic temperature of –4.1?C (Figure 1) then, if the concentration of MgSO4 is less than the eutectic concentration (about 1.7 m), ice will form until the solution concentration reaches its equilibrium concentration at the given temperature on its phase diagram. If the concentration is greater than the eutectic concentration, MgSO4 solid will precipitate until the concentration reaches equilibrium. It is for this reason that ice can be selectively produced in FC processes (Randall & Nathoo, 2015)."

Jan 1, 2017

By Liming Yuan

Three-dimensional computational fluid dynamics (CFD) modeling is conducted to simulate spontaneous heating in a large-scale coal chamber with a forced ventilation system. Spontaneous heating is modeled as the low-temperature oxidation of coal using kinetic data obtained from previous laboratory-scale spontaneous heating studies. Heat generated from coal oxidation is dissipated by convection and conduction, while oxygen and oxidation products are transported by convection and diffusion. The water vapor transfer and the effect of heat of wetting are not modeled. The CFD model is validated by comparing simulation results with test results from U.S. Bureau of Mines experiments conducted in the coal chamber. The model predicts lower temperatures in the early stage but agrees well on the induction time for spontaneous heating. The effects of airflow rate and order of reaction on the spontaneous heating process are also examined. The calibrated CFD model is found to be useful for predicting the induction time for spontaneous heating in underground coal mines.

Jan 1, 2009