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L. S. Austin, Denver, Colo. (communication to the Secretary) : Mr Hartman says (p. 4 of the pamphlet) that the penetration of air into the crucible of the blast-furnace " is, of course, a function of the diameter of the nozzle." To this I would emphatically take exception. Fig. 1 represents a vertical ideal section of tuyere, cruciblewalls and charge, immediately at the tuyere, in which the currents of air are represented, both in quantity and in direction, by the tortuous black-lines emanating from the nozzle-opening and passing through channels of the least resistance. As an electric current, flowing by various conductors to a common point, is carried in quantity inversely as the resistance of those conductors, so here the air ramifies through the most open cavities or channels, relatively little of it passing where the resistance due to fine materials is great. This figure represents the course of currents in the vertical plane only. As a matter of fact, they pass away in every plane, as opportunity offers. The effect of blocking or decreasing the area of the nozzleopening would certainly only decrease the quantity of air entering by that particular tuyere, without assisting penetration. The large channels (b, b, Fig. 1, for example) would still carry the larger part of the air, while again the smaller channels (a, a, a) would continue small and take no larger percentage of the air than before. These channels momentarily change, however, with the slow descent of the coke. Further on (p. 5), Mr. Hartman describes the dispersive effect of a single lump of fuel. He has only to conceive the entire spaces before the tuyere-nozzles as filled with such lumps, in order to parallel the condition of affairs I have just explained. It is where the large pieces of the charge come down, that the mass is the most open, and the blast passes most freely. On the other hand, wherever the fine ore collects combustion proceeds slowly, because of the smaller supply of air. The

Jan 1, 1899

By Jared Onyirimba, Jim Viellenave, Hal Demuth, Dale Verran, Chad Sorba, Errol Lawrence, David Bronkhorst

As outlined within the Denison Mines Corp’s (“Denison”) Pre-Feasibility Study ("PFS") completed in late 2018, additional work is required to increase confidence and reduce risk associated with the application of the In-Situ Recovery (“ISR”) mining method at the Phoenix deposit, located on the Wheeler River Uranium Project (“Wheeler River” or the “Project”) in northern Saskatchewan. The successful application of ISR in any geological environment largely hinges on three fundamental requirements, 1) permeability (of the deposit), 2) containment (of the mining solution) and 3) leachability (of the mineralization). Denison has designed several staged technical programs to progressively reduce risk associated with these requirements as the Company advances the Project toward a Feasibility Study (“FS”) and Environmental Impact Assessment (“EIA”). This paper will discuss the scope and results of certain technical programs being undertaken as the Company aims to develop the first ISR mining operation in the Athabasca Basin.

Jan 1, 2020

By Pradeep K. Rohatgi, Clyde M. Adams

Dendritic aggregate of ice formed on freezing of aqueous soluitions has been studied. Chlorides of sodium, potassiutn, lithiunz , and hydroget1 were used as solutes. The spacing between ice platelets or den-drites was experimenlally found proportzonal to the square root of freezing time when the freezing rate was constant from beginrting to end of solidification; the constant freezing rates were obtained during freezing of small droplets of aqueous soliitions surrounded by relatively large heat sinks. The transverse growth velocity of the ice platelets is proportional to the square root of the freezing rate. During unidirectional freezing from a constant temperuture chill, the solution at each location is subjected to a spectrum of freezirtg rates. The freezing rate is ini- FREEZING of solutions has been a subject of investigation in many disciplines. Aqueous solutions offer the advantage of transparenty; their study is of special significance due to the increasing interest in freezing processes for desalination. In addition dendritic solidification of aqueous solutions is in many ways analogous to freezing of metallic solutions. Aqueous solutions of most ionic salts freeze with tially low, passes through a maximum, and then decreases until solidificatimz is complete. The den-drite spacing increases linearly with the distance from the chill surface; it is inversely profiortional to the square root of the maximum freezing rate. The dendrite spacings in the two systems (the constanl freezing rate and the varying freezing rate) are equal, when the maximum freezing rate of the varying freezing rate system equals the average freezing vale of the constant freezing rate system. Mass transport in interdendritic liquid duriug solidificatiotz is analyzed; the experimental observations indicate that maximum concentration difference (AC) and supercooling (AT) in the interdendritic liquid are indepexdent of freezing rate. the separation of practically pure ice crystals from the liquid phase; with very few exceptions there is no solid solubility of ionic salts in ice. As an ice crystal grows there is rejection of solute from the moving interface into the liquid. Since the rejected solute moves primarily by diffusion, concentration gradients are established in the liquid. The highest solute concentrations are found in liquid immediately adjacent to liquid-solid interfaces and lowest concentrations farthest from the interface. Two-phase equilibrium obtains only at the solid-liquid interface; at other locations the liquid becomes supercooled because temperature gradients are negligible compared to concentration gradients. This is an immediate consequence of the fact that thermal diffusivities are considerably higher than mass diffusivities.

Jan 1, 1968

By S Jahanshahi, D R. Swinbourne

A knowledge of the value of the activity coefficient of cobalt oxide in slag as a function of composition and temperature is necessary if effective strategies are to be devised to maximise the recovery of cobalt in nonferrous smelting processes. This work reviews previous studies and shows that comparison and evaluation of the results is hampered by variations in the choice of standard states for the species. Published results have been recalculated to a common set of standard states with a preferred value for the Gibbs free energy of formation of cobalt oxide. It has been shown that the value of the activity coefficient of cobalt oxide referred to the solid standard state in iron silicate slags is approximately two, at temperatures from 1523 to 1623¦K. It is suggested that some contradictory results are most likely due to errors in the measured partial pressure of oxygen.

Jan 1, 1998

By J. E. Ostberg, G. Phragmen, A. Hultgren, S. Wohlfahrt

Detailed study was made of a number of rimming ingots, both low and high carbon, and especially upon effects of superimposed air pressure. Requirement to suppress core bubbles is between 10 and 15 atm; at 6.5 atm freezing was in semikilled manner and at 3 atm, steel was of rising type. Probable mechanism of freezing under various conditions is discussed. AN earlier paper' reported an investigation made by a committee for studying rimming steel ingots appointed by Jernkontorets in Stockholm. The present paper is the outcome of some further work done by the same committee. Since the characteristics of ordinary rimming steel are connected closely .with the amount of gas liberated during freezing and since this amount of gas is governed by the pressure, it was considered of interest to ascertain in what manner and to what extent definite pressures applied to the top of the liquid steel in the mold would affect the solidification process and the consequent structure of a rimming steel of ordinary composition. The experiments were made at the Domnarfvets Steel Works. The steel was made according to normal practice in a 4-ton Rennerfelt electric furnace. Ferromanganese was added in the furnace; no aluminum was added, with one exception. Analyses of the four heats are given in Table I. The top-poured ingots measured about 12 in. sq x 48 in. and weighed about 1300 lb. One or two ingots of each heat were allowed to solidify under pressure, using a special device for admitting compressed air to the upper closed part of the mold, as shown in Fig. 1. A heavy plate sealed with asbestos was bolted to the top of the mold. The plate had a tapered aperture for pouring. Immediately after pouring the hole was closed by a wedged plug, and compressed air was admitted through a hole in the plug. Because of some delay in applying the plug, full pressure was not reached immediately. The pressure was adjusted to the desired value as indicated by a manometer. In order that the interior of the ingot might have the benefit of the pressure, the freezing of the top crust was delayed by a refractory lining applied to the top part of the mold, Fig. 1. Ingots were also cast from each heat without applied pressure, and with and without refractory lining at the top. Axial sections of ingots were cut either of the whole ingot or of some part of it of special interest; sections were polished and usually etched.' To facilitate description of structures the following terms may be used for different types of ingots solidified under gas evolution: 1. Box-hat or boot-leg ingot: Abundant gas evolution during casting and during rimming; no rim holes. 2. Normal rimming ingot: Lively gas evolution during rimming; usually rim holes in lowest part of

Jan 1, 1952

By L. S. Jeffrey

Estimates for South Africa?s coal recoverable reserves made in 1999range from nine to 59 billion tons; latest estimates by the Minerals Bureau suggest that 33 billion tons is a more likely figure. As much as 70% of that coal is located in the Waterberg, Witbank, and Highveld coalfields, as well as lesser amounts in the Ermelo, Free State and Springbok Flats coalfields. However, the Witbank and Highveld coalfields are approaching exhaustion (estimated 9 billion tons of recoverable coal remaining in each), while the coal quality or mining conditions in the Waterberg, Free State and Springbok Flats coalfields are significant barriers to immediate, conventional exploitation. New extraction technologies, technologies exploiting the energy content of the coal in situ, as well as suitable uses and markets for low-grade, high-ash coal are required before the country can utilize its admittedly vast coal resources. Major challenges for exploiting some Limpopo province coalfields are severe water shortages, insufficiently developed infrastructure, fragile environments and poor roof conditions due to the depth and complex geology. In the Central Basin (Witbank, Highveld and Ermelo coalfields) technical innovations for thin seam extraction, economic mining of both pillar coal and intrusion-fragmented resource blocks and the utilization of lower-grade coals are required. The success of the fluidized bed combustion technology is necessary to utilize the low-grade coals of the Free State and Molteno coalfields, while environmental exemption for past problems, together with strategies for mining small, disjointed thin-seam resource blocks, is required in KwaZulu-Natal. Clean coal technologies, coal cost and quality, environmental considerations, sustainable development, the growth of the South African economy and Government?s regulation of the electricity industry are the main challenges to the continued use of coal as South Africa?s primary energy source.

Jan 1, 2005

By I. Lowthian Bell

THERE has been probably no improvement introduced into the manufacture of iron which created more surprise in the minds of practical smelters and of scientific men than Neilson's discovery of the hot blast. In 1829, Messrs. Dunlop & Co. consumed at the Clyde Works, near Glasgow, nearly 7 3/4 tons of coal to make a ton of pig iron, of which about 20 cwts. was employed under the boilers of the blowing engines, leaving nearly 7 tons for the consumption of the furnace itself. In the year 1833, by heating the air to 612° F. (322° C.), they reduced the 7 3/4 tons to 3 tons by the mere burning of 8 cwts. of coal in the apparatus for raising the blast to this temperature. The statement just given is strictly true in a commercial sense, but when we come to consider the question as one of physical science, it is necessary to eliminate some of the conditions which conduced to so extraordinary a result. Anterior to Neilson's time the fuel employed in smelting iron was coke, and it was supposed at that period, erroneously, however, that coal in its raw state, when burned with cold air, was totally unfit for the purpose in question. This mineral, as it was obtained from the Lanarkshire coal-field, contained about 35 per cent. of volatile matter, but the process of charring it was performed in so unskilful a manner that instead of receiving 88 cwts. of coke from 135 cwts. of coal, 60 cwts. only was the product of the operation. Again, the reduced consumption of carbon in the furnace itself was accompanied by a corresponding diminution of blast, and this was followed by an economy of half a ton in engine coal. After making a proper allowance, however, for all these collateral circumstances, we are within the mark when we admit that in actual coke, which is really the form the fuel has to assume before it is burnt in the blast-furnace, not less than 30 cwts. was saved by heating the blast to 615° F. (322° C.). This unexpected economy, be it remembered, was obtained by the combustion of the 8 cwts. of coal, somewhat wastefully applied in the hot-air apparatus. Numerous have been the opinions advanced by different authorities in the scientific world to account for the apparent anomaly, but none,

Jan 1, 1877

By I. Lowthian Bell

THERE has been probably no improvement introduced into the manufacture of iron which created more surprise in the minds of practical smelters and of scientific men than Neilson's discovery of the hot blast. In 1829, Messrs. Dunlop & Co. consumed at the Clyde Works, near Glasgow, nearly 79 tons of coal to make a ton of pig iron, of which about 20 cwts. was employed under the boilers of the blowing engines, leaving nearly 7 tons for the consumption of the furnace itself. In the year 1833, by heating the air to 612' F. (322' C.), they redoccd the 79 tons to 3 tons by the mere burning of 8 cwts. of coal in the apparatus for raising the blast to this temperature. The statenlent just given is strictly true in a commercial sense, but when we come to consider the question as one of physical science, it is necessary to eliminate some of the conditions which conduced to so extraordinary a result. Anterior to Neilson's time the fuel employed in smelting iron was coke, and it was supposed at that period, erroneously, however, that coal in its raw state, when burned with cold air, was totsally unfit for the purpose in question. This mineral, as it was obtained from the Lanarkshire coal-field, contained about 35 per cent. of volatile matter, but the process of charring it was performed in so unskilful a manner that instead of receiving 88 cwts. of coke from 135 cwts. of coal, 60 cwts. only was the product of the operation. Again, the reduced colisumption of carbon in the furnace itself was accompanied by a corresponding diminution of blast, and this was followed by an economy of half a ton in engine coal. After making a proper allowance, however, for all these collateral circumstances, we are within the mark when we admit that in actual coke, which is really the form the fuel has to assume before it is burnt in the blast-furnace, not less than 30 cwts. was saved by heating the blast to 615° F. (322° C.). This unexpected economy, be it remembered, was obtained by the combustion of the 8 cwts. of coal, somewhat wastefully applied in the hot-air apparatus. Numerous have been the opirlions advanced by different authorities in the scientific world to account for the apparent anomaly, bat none,

By Sanjiv Dhanjal

"Often mineralogy dictates the physical properties of a material rather than chemistry. This in turn affects how that material behaves in a process plant, and whether optimum conditions for refining one mineral are different to those for refining another. For example how does refining copper from chalcopyrite differ to refining copper from bornite?Minerals are naturally occurring inorganic solids that have a definite chemical composition and an ordered atomic (crystalline) structure. X-ray diffraction is a common and highly developed method to identify and quantify minerals. X-rays are fired onto a material and the mineral is identified by the angles where the diffracted X-rays are in phase.Most X-ray analyzers are laboratory based. A sample is prepared and analyzed by a detector that travels in an arc to collect the diffraction pattern. COSMA has a curved detector which picks up the complete x-ray pattern instantaneously. Therefore, material is collected and transported through the machine where is it is analyzed continuously.COSMA measures about 0.5 tons of material per day, while laboratory analyzers measure a few grams at a time. Real time data trends are produced allowing for improved process evaluation and automatic control. The COSMA on-line system has taken X-ray diffraction out of the laboratory into the field.There are a number of systems in operation in cement production. It is recognized that on-line mineral analysis has a role in many other processes. This paper presents the technology and invites further discussion should the technology be beneficial to members of the audience.INTRODUCTIONThis article describes COSMA, a system that provides direct and continuous on-line mineral analysis using X-ray diffraction in the field. While X-ray diffraction is a common technique used in mineral analysis, the time from sampling to analysis can be hours and plant operators typically do not get the data in time to control a process or respond to an upset. COSMA provides rapid measurement, analysis and feedback of data, in real time. This provides powerful information that can be used to optimize operation, thereby reducing costs and increasing quality."

Jan 1, 2009

By C. M. Frost

The hydrodesulfurization characteristics of a residual fuel prepared from Wilmington, Calif., crude oil were determined at temperatures from 600° to 900° F, pressures of 200 to 800 pSig, and space velocities from 0.2 to 2.0 Vo/Vc/hr, using cobalt molybdate type catalysts. A prediction equation, developed from the experimental data, satisfactorily predicts the fraction of total sulfur that can be removed under any combination of operating conditions within the ranges investigated. Yields and properties of the low sulfur product are correlated with the fraction of total sulfur removed. Kinetic calculations show that the apparent reaction order and activation energy change with space velocity and temperature.

Jan 1, 1970

By C. Bucknam, M. McComb

Mercury and silver polythiocarbonate sludge that was generated from the pilot testing of optimized mercury removal from cyanidation pregnant eluate solutions prior to Merrill-Crowe recovery of gold and silver were tested for long term stability at Newmont Metallurgical Services. Sludge samples were mixed with heap leach residue to simulate disposal of the sludge in spent or active areas of the heaps and leached for twenty weeks with water and cyanide leaching solution, respectively. Leach testing results are presented as well as analysis of the sludge using scanning electron microscope techniques down to the <1000 nanometer scale.

Jan 1, 2007

By W Patton

Investment decisions in the mineral resources sector are made on the basis of an assessment of the economic potential for a mineral deposit. Given the supporting information for the location, scale, and quantity of the commodity of interest, miners and investors aim to make risk-informed decisions when considering further investment. The objective of resource classification is the synthesis of various types and quantities of geologic information used in resource model construction to assign confidence categories to the estimated mineral resources, which can then be used to support informed economic decisions. In this paper a risk-based classification scheme for iron ore mineral resources using conditional simulations is presented. The method involves categorisation of each block according to a confidence level, considering expected recoveries from a kriging model over mining production volumes. The realisations of the simulated model are used to assign risk-based confidence categories to zones of the ore deposit. One motivation for this work is to assess the sensitivity of the scheme to geologic uncertainties. Specifically, that which uncertainty in the layout of mineralising alterations and weathering overprints influence variabilities of associated rock properties and the likelihood of obtaining expected ore recoveries. It is shown these risks have material implications for a project’s economic potential. How the scheme can be extended to the grade control context and the value subsequent grade control activities is also quantified.

May 24, 2023

By M. G. Benz

The superconducting performmce of diffusion-processed Nb3Sn is influenced by its micro structure. High isotropic transverse current density may be achieved in this material by a process which forms a precipitate of ZrO, within the Nb3Sn. FOR an ideal type-I1 superconductor, little or no transport current can be carried in the mixed state; i.e., little or no transport current can be carried above the lower critical field H,,, where the field penetrates abruptly in the form of current vortices or fluxoids, even though full transition to the normal state does not occur until the upper critical field H,,.&apos; Fortunately, nonideal type-I1 superconductors can be readily obtained and these carry large transport currents up to the upper critical field H. Both theoretical and experimental investigations have attributed this current-carrying capability for nonideal type-I1 superconductors to pinning of the fluxoid lattice by heterogeneities in the microstructure of the superconducting material. These heterogeneities may take the form of dislocations or dislocation clusters,2"5 grain boundaries: structural imperfections introduced by phase transformations; radiation damage,8"10 or precipitates.11"15 Nb3Sn formed by diffusion processing is a type-I1 superconductor. Heterogeneities are needed for high superconducting critical currents above H,,. This paper will cover: a) what the microstructure of diffusion-processed NbSn looks like; b) what changes in the microstructure take place when the system is doped with precipitates, and c) how these changes in microstructure influence the superconducting critical currents. EXPERIMENTAL Preparation of Samples. Diffusion processing was used to form the Nb3Sn. The procedure used was as follows: a) coat the surface of a niobium tape with tin; b) heat-treat this tape at a temperature above 930°C to form a layer of Nb3Sn at the Sn-Nb interface. Such a layer of NbsSn is shown in Fig. 1 The thickness of the NbsSn layer formed was controlled by the time and temperature of the heat treatment. The same general procedure was used for preparation of both undoped samples and samples doped with a precipitate. An additional step was included in the preparation of the doped samples which consisted of internal oxidation of zirconium to form ZrOn. The details of the doping process will be reported in a later paper. Sample Testing. The Nb3Sn tape samples were soldered to a copper or brass shunt. Current and voltage leads were then attached to the sample in the usual four-probe resistance measurement configuration. The sample was cooled to 42°K. In some cases it was cooled in the presence of a high magnetic field and in other cases with the field turned off. The results were the same for both cases. The samples were oriented in a configuration with field transverse to current but could be rotated such that the angle between the field vector and the wide side of the tape sample could be changed. Measurements up to 100 kG were done in a superconducting solenoid and measurements above 100 kG in a water-cooled copper magnet at the MIT National Magnet Laboratory. Once the test field was reached, the current in the sample was increased until voltage was detected across the sample. The critical current was taken as the current at which voltage was first detected in excess of background noise. In most cases this was 1 to 2 x 10~6 v for a— in.-wide sample carrying several hundred amperes with a in. separation between voltage leads and with a 10 "-ohm shunt resistance. RESULTS AND DISCUSSION Microstructure. Examination of the microstructure of the undoped Nb3Sn shows rather large-diameter (1 to 2 columnar grains growing outward from the niobium surface toward the tin surface. As the layer is made thicker by longer diffusion times, these grains grow longer. Few new grains are started. Transmission electron microscopy shows little or no second-phase material within the bulk of the Nb3Sn layer. The microstructure of a diffusion-processed NbsSn layer changes quite drastically when the system is doped so as to form a precipitate within the NbsSn layer. Instead of large-diameter columnar grains of NbaSn forming, smaller-diameter (0.5 to 1 ) equiaxed grains of Nb3Sn decorated with the precipitate form. Fig. 2 shows a transmission electron micrograph of a Nb3Sn layer doped with zirconium oxide. This layer has been etched so that one may look between the grains

Jan 1, 1969

By M. A. Elliott

The technology of gasifying coal to produce synthesis and pipeline gas has advanced significantly in the Past 20 to 30 years. This period has seen the extensive use of oxygen in coal gasification, the development of suspension gasification processes and fluidized-bed gasifiers, the operation of various gasification processes at elevated pressures, and operation of gasifiers under slagging conditions. These developments are discussed, and their application to commercial and pilot plant gasifiers is reviewed. Typical processes for synthesis gas production are described, and operating results are compared. Pipeline or high-Btu gas may be produced from coal either by catalytic conversion of synthesis gas to methane, or by the direct reaction of coal with hydrogen (hydrogasification) to produce a methane-rich gas. Neither of these methods has been applied commercially, but developments pertaining to each of them are reviewed, and general processing schemes are discussed. The use of coal as a raw material for manufacturing gas has a long and distinguished history. In fact, the gas industry began in the early 1800&apos;s when William Murdock demonstrated that it was feasible to produce and distribute gas made by retorting coal. Coal was used exclusively for gas manufacture until the middle of the 19th centruy, when Lowe invented the carbureted water gas process. In that process, coke was one of the raw materials used, so coal was still an important factor in gas manufacture. However the availability and relatively low cost of natural gas in the United States, and its widespread distribution by long-distance pipelines in recent years, has virtually eliminated the use of coal as a raw material for gas manufacture in this country. It should not be inferred from the foregoing that the technology of coal gasification has remained static in the United States and abroad. In fact, in the past two decades many new concepts have been developed in both the science and the technology of gasification. This progress has been a result of the considerable expansion in research on the fundamental chemistry and physics of gasification reactions, and in development work on gasification processes. This expansion in effort stems in part from increased interest in the use of gas as a raw material for the synthesis of chemicals and liquid fuels, and in part from the need to develop methods for gasifying coal and other solid fossil fuels to ensure a long-range supply of energy in the form of gaseous fuel. In these uses of gas, synthesis gas, a mixture of hydrogen and carbon monoxide in various proportions, is the starting material. It may be converted catalytically to gaseous and liquid hydrocarbons and other chemicals, or to hydrogen for use in hydrogenation or reduction reactions. Since coal is our most abundant fossil fuel, it is inevitable that one day it will regain its prominence as a raw material for gas manufacture. It is of interest, therefore, to consider the present status of gasification technology, directing attention particularly to advances made in recent years. Inasmuch as many comprehensive treatises l-3 and review4-7 of gasification technology are available, no attempt will be made in the present review to cover all processes in detail. Instead, the discussion will be concerned chiefly with typical processes embodying the advances that are most likely to be generally applied. ADVANCES IN GASIFICATION TECHNOLOGY For purposes of this discussion the starting point will be the conventional processes that were used for many years for the complete gasification of coal. These were: 1) carbonization in coke ovens followed by gasification of coke with air and steam in cyclic water-gas generators, and 2) fixed-bed air-blown producers. Both of these methods have obvious deficiencies when we consider that the ideal complete gasification process would be a single-stage, continuous

Jan 1, 1961

By Peter G. Groer

The commonly used exact methods (1-2) to determine the WL measure the total a activity or the total number of a counts during three preselected time periods. Due to the half-lives involved (TRaB = 26.8 min, TRaC = 19.7) I these methods take 3S minutes to complete the a activity Ra measurements. Methods using the total a counts, obtained at times less than about one RaB half-life after the end of sampling run into statistical 214 problems. These methods are almost blind to RaB (Pb214) as a consequence of its relatively long half period (see above) and the fact that RaB is a ß emitter. The way out of this dilema is to measure RaB directly through its ß activity. Since RaB&apos;s daughter Rae (Bi214) is also a ß emitter, the two f3 spectra have to be separated to obtain RaB alone. How this is accomplished 1s described in subsequent sections describing the theory of the IWLM and its calibration. 2.0 THEORY The IWLM samples air for two minutes and counts this airs ample for two minutes starting 3 sec after the end of the sampling period. The instrument has three channels. The lower a channel, the upper a channel, and one ß channel. The total RaA counts observed are accumulated in the lower a channel, the total RaC? counts are stored in the upper a channel. The total ß counts from RaB and RaC are recorded in the ß channel. These three quantities are functions of NA, NB, and NC, the unknown concentrations

Jan 1, 1975

By Stephen Hardcastle

Supplying ventilation in underground metal mines can be one of the most energy demanding services required to support production activities. Consequently, as energy, in the form of electricity or combustible fuels can be expensive and their unit cost is expected to increase, there is significant interest in reducing the overall demands of a mine?s ventilation system through such initiatives as controlling ventilation based upon demand and exploring other power alternatives to the current usage of the diesel engine in mobile mine vehicles. However, determining the benefit of any energy saving technology is complex and not universal applicable across the industry, consequently they have not been widely adopted. For these technologies to succeed they must be strategically applied based upon sound business cases. The intent of this paper is to provide information on some of the prospective control strategies and their potential impact on the power consumption related to supplying ventilation.

May 1, 2007

By Paul F. Ziemkiewicz, Aaron Noble, Christopher R. Vass

Many modern industries rely on rare earth elements (REEs) to produce products that are essential to both civil and defense applications. In a prior study (Vass et al., 2019), we showed that REE grades in acid mine drainage (AMD) and associated byproduct precipitates from AMD treatment (AMDp) warrant evaluation as a feedstock for REE production. The current work extends that effort through a broad survey of 141 AMD treatment sites in Northern and Central Appalachia. In this study, 185 raw AMD and 623 AMDp field samples were obtained and analyzed to assess the REE and major metal concentrations. Results show that an average of 282 μg/L and 724 g/t of REEs occur in AMD and AMDp, respectively. Additionally, both basins contained similar distributions of REEs, and these distributions tended to favor heavy and critical REEs when compared with traditional REE ore deposits. 

By John T. Cumberlidge

The Groveland deposit, in the Upper Peninsula of Michigan, consists of an E -W trending overturned syncline of Middle Precambrian Vulcan iron formation. At Groveland, the Vulcan formation can be divided into four units or facies. The total succession may be more than 550 feet thick, and consists of a basal unit composed of a lean chemical quartzite with traces of magnetite; a non-banded, partly clastic unit characterized by the preponderance of hematite over magnetite; a transition unit of well-banded magnetite-bearing iron formation interbedded with non-banded oolitic hematite; and a well-banded magnetite-quartz silicate unit at the top of the exposed sequence. The present magnetite-hematite ratios of different units within the orebody are considered to be a primary (post-diagenetic) feature of the original sediment. Subsequent regional metamorphism has increased the grain size of the original iron oxide minerals, but did not appreciably alter the oxidation state of the original sediment.

Jan 1, 1964

By J. B. Rasmussen

As part of a purchase of a fleet of Caterpillar 785 trucks, Round Mountain Gold Corp., Cashman Equipment Co. and Caterpillar Inc. entered into a four-year contract for the major maintenance of the fleet of trucks. This contract includes fixed costs and guaranteed availability. The results have been excellent, and the fleet of trucks performs well. History The Smoky Valley Common Operation is a unique mine. Through a mixture of diligence and foresight, it has become the largest open-pit, heap leaching gold mine in the world. This was no small feat considering the remote area surrounding the mine. Round Mountain is located in north-central Nye County, NV. To the east of the town and mine lies the Central Toquima mountain range. To the west is the Toiyabe mountain range. Between them is the Big Smoky Valley, a flat expanse of sagebrush, salt grass and fine dirt.

Jan 1, 1991

By W. T. Abel

The rate of the steam-carbon reaction, which is of fundamental importance to coal gasification, was determined by passing steam over graphite specimens suspended in an electrically heated tube. The measurements were made at 1,900° to 2,400° F. and at steam-feed rates of 0.1 to 2.0 moles of steam per mole of carbon per minute. At the maximum steam-feed rate, the reaction rate of carbon ranged from 0.4 percent per minute at 1,900° F. to 7 percent per minute at 2,400° F. Up to about 2,200° F., the steam-feed rate had only a slight effect; above this temperature, it limited the reaction velocity when the final mole fraction of steam in the reaction products was much less than 1.

Jan 1, 1962