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By Thomas M. Barczak

Wood cribs have been the dominant form of supplemental support in coal mining for many years. Recently, there has been a renewed interest in prop supports as a replacement for wood cribbing due to the increasing cost of mine timber and engineering advancements in prop design to improve their stability and yield capability. Prop supports generally consume less material, can be installed in less time with less labor, and provide less restriction to mine ventilation than wood crib supports. Several prop supports are now available or under development'. These include: (1) Strata Products Propsetter? Support System; (2) Heintzmann ACS and Super Prop; (3) MBK-Hydraulik MEGA prop; (4) Advanced Mining Technology Inc. (AMTI) BTS Mortar prop; (5) Dywidag Coal Post; (6) Western Support Systems YIPPI support; and (7) "The Can" support by Burrell Mining Products. A comparison of the performance and cost of these support systems to wood cribs is made to provide mine operators with information needed to assess their application potential. Examples of current underground installations are discussed. Included in this assessment are full scale tests of these supports conducted in the U.S. Bureau of Mines' Mine Roof Simulator.

Jan 1, 1995

By R. E. Head

[Surveys of the manganese situation conducted by the Geological Survey and other agencies have distinctly established the fact that the tonnage of high- grade manganese ore in the United States is relatively small. It is therefore obvious that large-scale production of manganese is possible only through beneficiation of low-grade material. ]

Jan 1, 1941

By S. Usui

In a previous article1 the methyl stretching vibrations for a series of xanthates and amines were reported, and the frequency of the methyl stretching vibrations in a homologous series of the alkyl compounds were shown to decrease exponentially with chain length and approach a limiting value corresponding to that of saturated hydrocarbon beyond six or seven carbons. These observations were explained quantitatively by the theory of Goto and Takenaka2 who proposed an equation relating the frequency shifts to the inductive effect of polar groups. As a result, the alkyl groups in the shorter chain heteropolar compounds were interpreted as becoming somewhat polar, and a good correlation was observed between the CH3-stretching frequencies and such surface chemistry parameters as contact angle, surface tension lowering, solubility, and critical micelle concentration" The substitution of fluorine atoms, the most electronegative of all atoms, for the hydrogen atoms in alkyl groups was expected to reverse the direction of the inductive effect within a heteropolar molecule, and its effect on the C-F stretching frequency shifts and on some surface chemical properties became of interest. In a recent study the C-F stretching frequencies of a series of normal perfluorocarboxylic acids and a few 1,1' -dihydroperfluoro alcohols were determined as a function of chain length and the results were compared with the corresponding hydrocarbon analogs. Furthermore, the nature of the induced polarity in the hydrocarbon and fluorocarbon groups was investigated through surface potential measurements at the interfaces of air-aqueous solutions of normal butyl alcohol and of l,l'-dihydroperfluorobutyl alcohol and through differential capacity and electrocapillary measurements at the interfaces of mercury-aqueous solutions containing the above two alcohols. Experimental Normal perfluorocarboxylic acids and 1,1' -dihydroperfluoro alcohols were provided through the courtesy of the 3M Company, St. Paul, Minnesota. Normal butyl alcohol was purchased from Distillation Product Industries, Rochester, New York. A Perkin-Elmer Model 621 infrared spectrophotometer was used to investigate the spectra in the frequency region of 1200 to 1270 cm-l with frequency scale

Jan 1, 1971

By Edward C. Stephens, Robert R. Coats

High-grade copper ore was discovered in 1932 in the long-dormant Mountain City (Cope) mining district, Elko County, Nevada. From 1932 to 1947, the one producing mine in the district, the Mountain City Copper Mine, produced 1,109,878 short dry tons of ore averaging 9.745 per cent copper, 0.274 ounces of silver, and 0.0057 ounces of gold per ton. The Mountain City Copper Mine is developed in eugeosynclinal rocks of Ordovician age, the Valmy Formation, which is part of the upper plate of the Roberts Mountains thrust. On the Valmy were deposited unconformably first, a elastic formation of Devonian or Mississippian age, the Grossman Formation, succeeded unconformably by a ·sequence of three conformable formations, the Banner, the Nelson, and the Mountain City. The Banner Formation probably is early Late Mississippian in age; the ages of the Nelson and Mountain City are not known precisely but are believed to be of Late Mississippian and Carboniferous(?) age, respectively. A thick formation of elastic rocks, limestone, and volcanics, the Reservation Hill Formation, has been thrust over the Mountain City. The age of the Reservation Hill is unknown but is presumed to be Pennsylvanian(?) and Permian(?). Several plutons of Cretaceous quartz monzonite intrude the Paleozoic formations; they and the intruded formations have been laid bare by erosion, and several sequences of volcanic rocks of Miocene and Pliocene age, and perhaps in part older, have been successively deposited on irregular erosion surfaces. The primary mineralization of the Mountain City Copper Mine is believed to postdate the deposition of the Nelson Formation and to predate the intrusion of the quartz monzonite. The primary ore bodies are lenticular in shape and are composed largely of quartz, pyrite, and chalcopyrite. The ore lenses, in general, strike northwestward and dip northward. They occur in the Valmy Formation within a definite stratigraphic sequence composed largely of shales with associated minor quartzite lenses. The ore is epigenetic. The principal ore body, the "200," was completely leached to the 200 level. Abruptly beneath the barren gossan was supergene copper sulfide ore, much of which assayed 50 per cent copper. The secondary copper minerals are sooty and massive chalcocite, bornite, and covellite. The supergene enrichment of the ore may have required a large part of Tertiary time.

Jan 1, 1968

By R. Hendrickson

In the 1940's a top blown water-cooled oxygen lance was developed to inject oxygen into liquid iron. This process, the LD or BOF process technique, today is used in 65% of the world's steel production, and represents the largest oxygen market for temperature enhancement in steel and non-ferrous smelting applications. There are three major approaches to the use of oxygen in metallurgical processes: (1) general enrichment of the air supplied to burners or tuyeres, (2) under-flame enrichment or injection, and (3) the use of an auxiliary oxy-fuel burner as a heat source. With each of these techniques there are technical and economic trade-offs.

Jan 1, 1990

The Iron Ore Company of Canada (IOC) is the largest manufacturer of iron ore pellets in Canada and its customer base covers North American, European and Asian steel producers. The company operates a mine, concentrator and a pelletizing plant in Labrador City, Newfoundland and Labrador, as well as port facilities located in Sept-Iles, Quebec. It also operates a 418-km (260-mile) railroad that links the mine to the port. IOC has approximately 1,900 employees. Its shareholders are Mitsubishi Corp. (26.18 percent), Labrador Iron Ore Royalty Income Fund (15.1 percent) and the international mining group Rio Tinto, which is its major shareholder (58.72 percent) and operator, with activities in more than 40 countries throughout the world. The IOC was incorporated in 1949 and by 1954 it had completed the Quebec North Shore and Labrador (QNS&L) rail line. IOC began mining in Schefferville, Quebec by 1954 and closed those operations down in 1982. In 1962, IOC commissioned the present day Carol Project consisting of mining, concentration and pelletizing facilities in Labrador City, Newfoundland. In 2004, IOC shipped its one-billionth tonne of ore on the QNS&L Railway. In 2005, IOC celebrated 50 years of mining history. The company expressed an interest in reducing the amount of oversize material (>1 m x 1 m x 1 m or 3.2 ft x 3.2 ft x 3.2 ft) being produced and its subsequent downstream effects, including in-pit sorting and reduction, damage to mobile equipment and significant delays in the loading pockets and the primary crushers. To achieve this goal, an oversize reduction project was undertaken by the mine that, to date, has significantly improved upon baseline measures. One key approach used to reduce the amount of oversize was the implementation of thicker emulsion. The introduction of a thicker emulsion provided more resistance to the forces created by dynamic water and reduced the infiltration of the emulsion into the cracks and fissures of the rockmass, resulting in reduced amounts of oversize and more consistent fragmentation throughout the muckpiles. Additionally, a significant reduction in nitrates leached into the mine water discharge has been realized. To determine the effectiveness of the oversize reduction project, IOC used a first-of-kind technology to assess fragmentation presented to the shovel at the digging face. A digital vision system (DVS) was installed on one of the shovels to capture images that were stamped with GPS locations. A large population of digital images were analyzed to produce a robust fragmentation distribution baseline that was used as one of the mine key performance indicators (KPI). Changes to blasting practice were subsequently measured against the baseline KPI to assess effectiveness.

Jan 1, 2011

By Freeman NV

The concept of an in stream analysis probe was developed at The Zinc Corporation (now Z.C. Mines) in the late 1960's and commercialised quite rapidly, by Phillips and then AMDEL, as an alternative to the established centralised systems (Courier, etc.). The developments which have taken place since that time are reviewed and current procedures and performance are described. An audit of the system, recently undertaken by AMDEL, has highlighted areas where improvements can be made. In 1988 the ISA system will become an integral part of a substantially upgraded process control system.

Jan 1, 1988

By H. A. Baumann, C. C. Wright, T. S. Spicer

A LTHOUGH the efficiency of coal utilization has A improved steadily since the turn of the century as a result of continued research and development, little of this increase in efficiency can be credited to improvements in the single retort stoker. There are still numerous problems connected with the burning of coal on this type of unit, the solution of which would be a stimulus to coal and stoker sales and a boon to the user. Among the more critical of these problems is that of burning slack bituminous coal of strong caking tendency and containing large percentages of fine material. With the increased trend toward mechanical mining, it may be expected that in the future an even larger percentage of the coal available for use on this class of stokers will contain higher percentages of the fine sizes, thus aggravating an already serious problem. During the war, the problem of efficient and economic burning of available coals on the single retort industrial stoker, particularly the class 4 stokers (301 to 1200 lb per hr), became quite critical in many localities. In addition to the inherent problems associated with the use of this class stoker, the coals available were frequently not those best suited for use on this equipment and the manpower shortage made it difficult as well as expensive for the consumer to provide the labor necessary to keep the iires in reasonably satisfactory condition. Although exact figures on the number of class 4 stokers are not available, the yearly tonnages of coal consumed are of considerable consequence and have been estimated* at between 15 and 20 million the stoker research staff of the Mineral Industries Experiment Station of The Pennsylvania State College was requested to study the performance of the single retort industrial stoker and to undertake a program of research on the more efficient burning of bituminous coal on this class of unit. Various aspects of overall problem have been investigated since the inception of this program in 1942, only one of which is here reported. General Considerations There are numerous factors which appear directly or indirectly to affect the overall performance of bituminous coal underfeed stokers, such as the caking or matting properties of the coal, the contact relationships between coal and air, the ash fusion characteristics, the burning rate, and the design of the stoker and furnace in which the coal is burned. An analysis of the influence of each of

Jan 1, 1951

By H. A. Baumann, T. S. Spicer, C. C. Wright

A LTHOUGH the efficiency of coal utilization has A improved steadily since the turn of the century as a result of continued research and development, little of this increase in efficiency can be credited to improvements in the single retort stoker. There are still numerous problems connected with the burning of coal on this type of unit, the solution of which would be a stimulus to coal and stoker sales and a boon to the user. Among the more critical of these problems is that of burning slack bituminous coal of strong caking tendency and containing large percentages of fine material. With the increased trend toward mechanical mining, it may be expected that in the future an even larger percentage of the coal available for use on this class of stokers will contain higher percentages of the fine sizes, thus aggravating an already serious problem. During the war, the problem of efficient and economic burning of available coals on the single retort industrial stoker, particularly the class 4 stokers (301 to 1200 lb per hr), became quite critical in many localities. In addition to the inherent problems associated with the use of this class stoker, the coals available were frequently not those best suited for use on this equipment and the manpower shortage made it difficult as well as expensive for the consumer to provide the labor necessary to keep the iires in reasonably satisfactory condition. Although exact figures on the number of class 4 stokers are not available, the yearly tonnages of coal consumed are of considerable consequence and have been estimated* at between 15 and 20 million the stoker research staff of the Mineral Industries Experiment Station of The Pennsylvania State College was requested to study the performance of the single retort industrial stoker and to undertake a program of research on the more efficient burning of bituminous coal on this class of unit. Various aspects of overall problem have been investigated since the inception of this program in 1942, only one of which is here reported. General Considerations There are numerous factors which appear directly or indirectly to affect the overall performance of bituminous coal underfeed stokers, such as the caking or matting properties of the coal, the contact relationships between coal and air, the ash fusion characteristics, the burning rate, and the design of the stoker and furnace in which the coal is burned. An analysis of the influence of each of

Jan 1, 1951

By P. Goosen

The paper presents a basic summary of the approach to hydraulic scale-model tests as may typically be applicable to slurry flow situations. A case study is presented illustrating how hydraulic scale-model tests can be of significant benefit in evaluating the performance of novel or unproven slurry handling equipment. In this case the equipment tested was a fan-shaped expansion piece used to spread the discharge from a launder over the full width of a dewatering screen. The tests showed that the device did indeed distribute the slurry flow both in terms of volume and solids mass, but not perfectly uniformly. Unfortunately the equipment was not taken beyond the model test phase. The scale-model test approach did, however, prove to be very useful as it is considered to have provided a good indication of the expected performance of the full-size unit. Significantly, this was achieved at very low cost compared to the cost of installing the device into the proposed plant and having to later change it out for an alternative or live with the less than optimal performance. The paper illustrates the value that can derive from applying hydraulic scale-model testing techniques to evaluating the performance of new or unusual slurry handling equipment. There is particular value in situations that do not lend themselves to numerical modelling.

Jan 1, 2007

By Sidney Katell

This Bureau of Mines study estimates typical capital investments, operating costs, and selling prices for two bituminous coal strip mines in the Eastern and Interior provinces and a subbituminous coal operation in the Northern Great Plains province. The annual productions were based on tonnage required to fuel a 250-million-standard-cubic-foot-per-day, high-Btu gas plant. The annual tonnage for the Eastern province mine is 4.8 million tons; for the Interior province mine, 6.72 million tons; and for the Northern Great Plains province mine, 9.2 million tons. It is assumed that the mines have a 20-year life. Wages and union welfare payments are considered as of December 6, 1974, under the terms of the Bituminous Wage Agreement of 1974, and costs for material and equipment are based on 1975 indexes. Initial capital investment varies: $65,137,900 for the 4.8-million-ton-per-year (MM tpy) mine in the Eastern province, $78,514,600 for the 6.72-MM-tpy mine in the Interior province, and $42,050,100 for the 9.2-MM-tpy mine in the Northern Great Plains province. Total capital investments for the Eastern province mine, the Interior province mine, and the Northern Great Plains province mine are $86,969,900, $109,378,500, and $78,543,500, respectively. Corresponding selling prices for the coal, per ton, are $6.94, $6.03, and $3.39, assuming a 15-percent discounted cash flow rate of return after Federal income taxes. These studies are considered typical for the areas involved. Costs will vary depending on specific locations in these areas.

Jan 1, 1976

By L. G. Austin, P. T. Luckie, R. R. Klimpel, R. S. C. Rogers

1. INTRODUCTION The Bond method(1.2) for sizing tumbling ball mills has been used successfully for many years. The primary purpose of the Bond calculation is to predict the mill size and mill power to give a desired capacity (Q tph) from a wet overflow ball mill in normal closed circuit operated with a circulation ratio of 2.5. The input to the calculation is the make-up feed size characterized by the 80%-passing size in micrometers (xG), the desired circuit product size characterized by the 80%-passing size (xQ), and an empirical grindability number (the standard Bond Work Index) determined by a standard test. A series of empirical correcting factors(2) are used to convert the results to open-circuit or dry grinding in grate discharge mills. The Bond method has two major engineering advantages: (i) it is very simple; (ii) experience has shown that it works for many circumstances, as a reasonable approximation, because it is based on direct conversion of test data to results measured on industrial mills. There are four main disadvantages of the Bond method. First, there will be a range of error for any specific mill and material and set of operating conditions because the method does not explicitly include several variables which are obviously important: (i) recycle ratio and classifier efficiency (ii) mixture of ball sizes in the mill (iii) variations of residence time distributions with mill geometry and slurry density (iv) lifter design (v) slurry rheology (vi) different underfilling or overfilling of the mill as flow rate is changed. Second, the Bond method explicitly assumes that specific grinding energy E is not a function of ball load, whereas industrial practice and laboratory tests(3) show that the specific grinding energy (to go from a specified feed to a specified product) is less for lower ball loadings than the ball loading for maximum mill capacity. Third, the method uses only the 80% passing size of circuit feed and product to characterize the size distributions, whereas mill capacity in general must depend on the shape of the feed size distribution and the product size distribution. The prime example of this is the use of the reverse closed circuit which removes some fraction of the make-up feed before it is

Jan 1, 1982

By Henry M. Howe

Many direct processes have been proposed for the treatment of oxidized ores of copper by reducing the copper oxide to the metallic state, and by separating it from its impurities by a subsequent fusion. The radical objection common to all the methods which have come to my notice, except those in which sulphur plays the prominent part, is that the very deoxidizing agent which effects the reduction of the copper oxide, inevitably reduces at the same time a very considerable part, if not the whole, of the iron which almost invariably accompanies copper in its ores. The result is that, when the ore is subsequently fused, a very great quantity of the already reduced iron separates from the slag along with the copper, alloying with it, and necessitating costly subsequent operations for its separation. Thus, at Perm, in the Urals," the product of the fusion of ferrnginous copper oxides is a mixture of one hundred and fifty-tive parts of highly cupriferous pig iron with two hundred and fire parts of very impure and ferruginous black copper, containing Pome 10 per cent. of' carbon and iron, though free from sulphur, and of course very difficult to refine. If, in order to avoid this reduction of iron to the metallic state, the reducing action be made feebler, it inevitably results that a considerable part of the copper as well escapes deoxidation; and, consequently, the slags are so rich that it becomes necessary to treat them subsequently in order to recover the copper which they contain. Thus,. in treating native copper, at Lake Superior, where the reducing action is purposely made feeble in order to prevent the deoxidation of the iron, the slags from the first fusion of the ore carry so much copper as to render it imperative to treat them again, which is done in a cupola. And yet, in spite of so far weakening the reducing action as to cause a notable slagging of the copper, a very considerable reduction of iron actually takes place. These are the two dangers which threaten the smelter of oxidized copper ores. If he wishes to avoid slagging his copper, he must have so strong a deoxidizing action as to reduce a great deal of his

Jan 1, 1879

By W. K. Connor, O&apos

Thermal Treatment Technology Division Albany Research Center, U.S. Dept. of Energy Oregon. This evaluation included a characterization study and direct smelting tests conducted in a bench-scale electric arc furnace (EAF). In contrast to other thermal treatment technologies considered for these wastes (i.e., fluidized bed combustion), direct smelting in the EAF can process 100% of the wastes without prior beneficiation, and utilizes solid oxidant additions (in this case iron ore) rather than air to oxidize the carbon. This solid oxidant addition is advantageous because it results in the production of several value-added furnace products. These products include cast iron resulting from the reduction of the iron oxides, baghouse dust containing virtually all of the zinc from the residues, and a clean (nonhazardous) slag product suitable for recycle as concrete aggregate or construction fill. Offgas from the smelting furnace also holds potential as fuel gas for cogeneration. The direct smelting tests conducted thus far were successful at producing the desired furnace products, exhibiting the potential for complete recycle of the waste pile. A cast iron product of comparable quality to conventional cast irons was produced, at nearly 80% iron recovery to the metal. The slag product was determined to be nonhazardous, based on the EPA TCLP. Lead and zinc partitioning to the dust product was greater than 99%. The material balance over the furnace indicates that for every ton of feed processed, 540 lb. of cast iron, 600 lb. of slag, and 150 lb. of dust would be produced. Energy consumption was roughly 1.10 kWxh/lb of feed material. Prior experience suggests that these figures measured in the bench-scale furnace would translate to 0040 to 0.50 kWxh/lb at the industrial-scale.

Jan 1, 2000

By C. J. Walker

The Bureau of Mines undertook a theoretical and laboratory study to determine the feasibility of using ethylene as a tracer for natural gas in underground gas-storage reservoirs. The study indicated that ethylene was a useful gas tracer in underground gas storages. Tracer losses were not excessive. Laboratory tests were conducted at pressures as high as 500 psia in both wet and dry consolidated-sandstone cores, evaluating tracer loss with gas blends containing natural gas with different concentrations of ethylene tracer. Under certain conditions losses were less than 17 percent.

Jan 1, 1966

By F. E. Lathe, L. Hodnett

This paper summarizes extensive data supplied by 40 copper converter plants in 18 countries, and includes a partial analysis and comments on the effect of converter slag composition and temperature on the fomzation and elimination of magnetite and the life of basic and neutral refractories. APRELIMINARY draft of this paper, including data from 26 companies which had submitted replies to a questionnaire, was presented at the Annual Meeting of the AIME held in New York in February, 1956. Publication was delayed in the expectation that additional replies would be received, and justification for the subsequent delay may be found in the fact that the present revised paper contains data from 40 converter plants situated in 18 different countries. The suggestion that a questionnaire be sent to the major copper and copper-nickel plants outside the U.S.S.R. and associated countries arose at the Los Angeles Annual Meeting in February, 1953, where several papers dealing with converter construction and operation were presented. In private discussions which followed, a group of metallurgists and refractories engineers raised the question why practices varied so much at different plants. Why did magnesite brick give superior service to chrome-magnesite in some plants but chrome-magnesite prove superior in others? Would metallurgical studies point the way to the development of still better refractories? Could magnetite formation be prevented in converter slags and reverber-atory furnace mattes? If this was feasible, why was a heavy circulating load of magnetite tolerated, when, in all probability, it increased copper losses in the reverberatory slags and, in some cases, made it necessary to shut down the furnaces periodically to clean out the accumulated magnetite? Was the sole purpose of coating brick with magnetite that of

Jan 1, 1959

By Armstrong RW, Middlin B

The development, design, construction and operation of the new Solvent Extraction/BCA process plant at Copper Refineries Pty. Ltd., Townsville is described.The process offers substantial savings in electrical power costs, improvements in plant hygiene, and a lowering of materials handling costs compared with conventional electrowinning technology.The solvent extraction process extracts arsenic from copper Tank House electrolyte using a tributyl phosphate (TBP) - kerosene solvent. The plant incorporates fourextraction stages, two scrub stages, and three stripping stages to produce an arsenic-bearing low-acid strip liquor. This strip liquor is mixed with copper sulphate, and neutralized with ammonia to form a copper (II) arsenic (V) crystalline product, bicupric arsenate (BCA). This product is then used in the manufacture of chromated copper arsenate timber preservatives (Royston 1982).

Jan 1, 1985

By N. Katsikaros, A. Lewis-Gray, P. Richards

"To optimize gold recovery in complex leach-to-electrowinning processes, Gekko Systems developed the Gekko resin exchange column (G-REX) as an intermediate step, using a highly gold-selective resin to isolate contaminant metals. The AuRIX®100 resin produced by Purolite is licensed exclusively to Gekko, with the G-REX column designed specifically for this resin. Operational experience has been gained at the Castlemaine Goldfields Ballarat gold mine. In near-continuous operation since 2008, the Ballarat plant treats unclarified concentrate leach solution. The extension of this technology to higher throughputs and more complex chemistry is discussed.RÉSUMÉ Afin d’optimiser la récupération de l’or dans des procédés complexes impliquant la lixiviation suivie de l’extraction électrolytique, Gekko Systems a développé la colonne Gekko de résines échangeuses d’ions (G-REX) comme étape intermédiaire, à l’aide d’une résine hautement sélective pour la récupération de l’or qui permet d’isoler les métaux contaminants. Gekko détient la licence exclusive pour la résine AuRIX®100 produite par Purolite, et la colonne G-REX a été spécifiquement conçue pour cette résine. C’est à la mine d’or Ballarat de Castlemaine Goldfields que l’expérience opérationnelle a été acquise. L’usine de Ballarat, en exploitation quasi-continue depuis 2008, traite une solution concentrée non clarifiée de lixiviation. L’extension de cette technologie à des capacités supérieures et à une chimie plus complexe est examinée.AURIX®100 RESINAuRIX100 resin is a crosslinked polystyrene alkaline resin developed by Henkel (Virnig, Mackenzie, & Adamson, 1996). The resin beads are off-white in colour and spherical, with a nominal size of 100% +600 µm. This resin is highly selective for gold and silver over many metals, by way of extracting precious metal–cyanide complexes from leach solutions with a pH of less than 11.5. The higher end of the pH scale produces the best selectivity according to the order of preference: Au > Ag > Hg > Zn > Ni > Cu > Co > Fe. Purolite produces the resin and Gekko Systems maintains licensing of AuRIX100 resin for use in its G-REX column, as part of its unique suite of gravity gold–handling equipment.Significant cost savings over carbon-in-solution (CIS) systems are realized with AURIX100 resin: approximately 4–12% in capital savings and 27–40% in operating costs (Virnig, Mackenzie, Katsikaros, & Gray, 2004). Additionally, AuRIX100 resin is not susceptible to fouling; that is, the resin does not load with inorganic salts or organic compounds that would affect the loading and extraction of precious metals. To counter any potential for fouling by inorganic salts, a dilute acid wash is periodically conducted in service on the resin to unblock resin pores."

Jan 1, 2017

By C. Hennesmann, D. Maijer, S. L. Cockcroft, P. Yo

"Die cast aluminum wheels are one of the most difficult automotive castings to produce because of stringent cast surface and internal quality requirements. As part of a collaborative research agreement between researchers at the University of British Columbia and Canadian Auto Parts Toyota Incorporated, work has been underway to predict heat transport and porosity formation in die cast A356 wheels. The basic heat transfer equations have been solved using the commercial finite element package ABAQUS to which specialized routines have been added to predict porosity. Preliminary work on predicting porosity formation focused on using the Niyama parameter as a measure of the probability of porosity. The latest version of the model incorporates a new fundamentally based porosity criterion, which takes into account the effect of hydrogen concentration. The development of this model together with its application to a series of cylindrical test castings as well as a production cast wheel are presented.I. IntroductionDie cast aluminum wheels are one of the most difficult automotive castings to produce because of stringent cast surface and internal quality requirements. Microporosity, in particular, is a common defect that can adversely affect wheel quality. The mechanism of microporosity formation in aluminum alloys is complex owing to its dependence on the interaction of a number of phenomena occurring during solidification including the decrease in hydrogen solubility, the decrease in volume, the development of the solidification structure, and the increase in difficulty in interdendritic feeding [1]. As a result, the amount, size, and distribution of microporosity is affected by a large number of casting parameters including thermal variables, melt composition, grain structure, modification, and inclusion content, making optimization by trial-and-error methodologies difficult.The use of criteria functions, based on thermal conditions during casting, offers a relatively simple approach to predicting microporosity. In practical terms, they are useful because they provide a straightforward method of assessing the impact of varying casting parameters on porosity through various thermal parametersl21 such as thermal gradient, cooling rate, solidification time, and solidus velocity. Drawbacks of criteria functions include insensitivity to varying hydrogen concentration and the limitation to qualitative predictions. Consequently, in aluminum alloys, attempts have been made to develop models incorporating the effects of hydrogen gas and microstructure evolution. However, these types of models represent a significant increase in complexity and sacrifice the simplicity and ease of application of the thermally based criteria functions."

Jan 1, 2001

By R. E. Head

[Surveys of the manganese situation conducted by the Geological Survey any other agencies have definitely established the, fact that the tonnage of high-grade manganese or in the United States is relatively small. It is therefore obvious that large-scale production of manganese is possible only through beneficiation of low-grade material. Deposits of low-grade manganese ore are being examined by engineers of the Mining Division of the Bureau of Mines to determine their size and possibilities as sources of manganese on a tonnage basis. The Metallurgical Division of the Bureau is developing and perfecting beneficiation processes with the objective of utilizing such low-grade ores. Microscopic study of these ores represents one phase of the research.]

Jan 1, 1941