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The recovery of fine hydrophilic gangue in flotation is related to the recovery of water. Water is carried by bubbles as a film and wake into the froth. The amount carried (entrained) depends on bubble size, gas rate and the subject of this paper, frother type. To isolate the effect of frother type from that of bubble size and gas rate, gas holdup is used as the correlating variable. Measurements were made using a bubble column (no solids) operated continuously with the overflow recycled. Continuous operation meant some foam depth was required to ensure only entrained water is recovered. Using an automatically controlled 7cm foam depth the overflow rate of water is used as a measure of 'water carrying rate'. It is shown that the common frothers can be grouped into four families based on the water carrying rate-gas holdup relationship.

Jan 1, 2006

By Donna Guillen, Matthew Lehar, Sebastian Freund, Jennifer Jackson, Helge Klockow

"Research and development is currently underway to design an Organic Rankine Cycle (ORC) system with the evaporator placed directly in the hot exhaust stream produced by a gas turbine (GT). ORCs can be used to generate electricity from heat that would otherwise be wasted, thus producing carbon-free energy. In conventional ORC configurations, an intermediate oil loop is used to separate the hot gas from the flammable working fluid. The goal of this research effort is to improve cycle efficiency and cost by eliminating the pumps, heat exchangers and all other added cost and complexity of the additional heat transfer loop by developing an evaporator that resides in the waste heat stream. Direct evaporation – although simpler and less expensive to implement than indirect evaporation of the working fluid – has historically been avoided due to a number of technical challenges imposed by the limitations of the working fluid. The high temperature of the hot exhaust gas may cause decomposition of the organic working fluid and safety is a major concern due to the high flammability of some of these working fluids. The research team has addressed these challenges and developed a new direct evaporator design that can reduce the ORC system cost by up to 15%, enabling the rapid adoption of ORCs for waste heat recovery. The ORC system is intended to integrate with the GT either as a retrofit or to be marketed as a single package, thus maintaining the manufacturer’s warranty.IntroductionWaste heat from turbines and engines used in industrial applications along with waste heat from industrial processes are exceptionally abundant sources of energy. If even a fraction of this waste heat could be economically converted to useful electricity, it would have a tangible and very positive impact on the economic health, energy consumption, and carbon emissions in the U.S. manufacturing sector. Land-based gas turbines are used in a broad range of applications to produce both shaft and electrical power. Most commonly known for generating electricity either as peaking units or as base load units, they are also used to directly drive pumps, compressors or other machinery requiring shaft power. Simple cycle gas turbines have the advantage of a short startup time relative to coal-fired and nuclear units, however, they incur a significant penalty on their efficiency. Large frame gas turbines usually are combined with bottoming steam-based Rankine cycles to increase the overall efficiency of the system and thereby improve their cost performance. Small-frame gas turbines with exhaust temperatures around 500°C could in principle benefit from steam bottoming cycles, but rarely use them in practice because of the high capital cost of the steam system. Particularly for base load small frame gas turbines, akin to those used in pipeline applications, an increase in efficiency is highly desirable."

Jan 1, 2011

By Diego Marquina, Jorge Terrones, Jose Morales

Si bien los incendios en el sector minero representan apenas el 1 % del total en todos los sectores, sus consecuencias son potencialmente críticas, por lo que resulta necesaria una evaluación constante de riesgos de incendio. En una evaluación de riesgo de incendio convencional (FRA, por sus siglas en inglés) se detallan los escenarios de riesgo de incendio a los cuales está expuesta una unidad minera, considerando las condiciones de la instalación, el análisis de los procesos, identificación de actos y condiciones subestándar, equipos u operaciones, reportes de incendio o amagos, entre otros factores que permitan identificar y analizar los escenarios de riesgo de incendio para definir su nivel de criticidad y aceptación del riesgo. Este enfoque diferenciado de FRA busca priorizar la inversión en protección contra incendios, al tomar en cuenta una tolerancia específica al riesgo de incendio, vida útil de la mina y la continuidad de procesos o recursos críticos para la operación en un nivel mínimo tolerable.

Sep 20, 2019

By A. F. Banks

"IntroductionThe typical potash processing plant recovers and/ or upgrades from 10% to 20% of its production through the recrystallization process. The feed to the recrystallization section consists of preconcentrated slurries of fine crystal size that cannot be raised to the required product grade by flotation and fine dusts also of low grade and too fine for compaction feed. It produces high grade white potash crystals that can be marketed as a high grade product or blended into the flotation products to raise their grade. In this chapter, a typical leaching (dissolving) and recrystallization operation will be discussed.The crystallization process makes use of the three phase system chemistry of NaCl, KCl, and H,O. The normal potash process operates on a temperature range of 75°F to 95 °F. A three phase slurry feed to the dissolving circuits will be within that range. The potash (KCl) is dissolved by heating the slurry in the presence of sufficient brine to a temperature of 190°F to 200°F. As the slurry is heated, the potash (KCI) dissolves and the salt (NaCI) precipitates. The potash rich brine is then clarified and the salt and other undissolved solids removed by thickening. Clarified brine becomes the crystallizer feed.The hot brine is cooled in evaporative cooling crystallizers. In cooling, the potash precipitates as a high grade white crystal. Crystallization is done in multiple effects to permit energy recovery and control of the process. In a four effect crystallizer the cooling is done by recycling mother liquor counter currently through the first two effect condensors and using brine pond brine for the cooling of the last two.The crystallizer product is removed from the last effect as a slurry at normal process temperature and is fed either to its own centrifuging and drying circuit or blended with the flotation product for centrifuging and drying."

Jan 1, 1989

By Christopher B. Kapes

To reduce concentrate dewatering and drying costs, the Concentrator Division at Phelps Dodge Morenci, Inc. investigated available filtration technologies. Numerous methods were explored, including: drum, disk, belt, pressure, hyperbaric, and ceramic media filtration. An economic evaluation of the individual filtration technologies indicated the advantages of ceramic media filtration for Morenci concentrates. This paper discusses the technological development culminating in the first full scale application of ceramic media disk filters in North America. Low moisture contents are obtained at high production rates and greatly reduced operating costs.

Jan 1, 1994

By Robert J. Wright

The purpose of this paper is to propose a classification of uranium deposits that is believed to be well suited to the needs of uranium exploration and resource assessment. By way of background some observations are offered about mineral exploration in general, and uranium in particular. Attention is first given to the we of models in mineral exploration. Some general principles of mineral deposit classification, the basis for model formulation, are then considered. Finally, the uranium classification is presented.

Jan 1, 1979

By Karl J. C. Harries

"1.1. WHAT ARE AGREEMENTS AND HOW ARE THEY FORMED?In order to have an agreement, at common law, there must be an offer, acceptance of that offer, and consideration passing between the parties. In addition, the material terms (i.e. the basics or substance) of the agreement must be discernible, preferably by means of documentation. Although these concepts may appear simple and straightforward, the law relating to them is voluminous and complex. Some brief comments are worthwhile.• Offer/acceptance: Both offer and acceptance should be in writing, but they need not be. The actions, conversations, and/or correspondence of the parties may constitute either or both of them. Notwithstanding, the local law or practice of a jurisdiction will impose some specific requirements for certain types of agreements. If these requirements are not met, the agreement may be unenforceable. For example, Ontario’s Mining Act requires transfers of unpatented mining claims to be evidenced in writing and recorded.1• Consideration: Consideration is usually thought of as being money, but it can be virtually anything, even “the premises” (i.e. the mutual covenants or promises contained in the agreement itself). In addition, if one party, relying upon the offer of another, does something to his detriment, then the doing of the act can be considered to be an acceptance of the offer and, under the legal concept of “detrimental reliance”, can also be consideration. Whether or not detrimental reliance exists will depend upon the circumstances of each case.2• Material terms: The requirement that the material terms of an agreement must be discernible does not mean that all of the terms of an agreement must be documented or even have been considered, just the basic or material ones. In addition, it will be up to a judge to decide what is material – not necessarily the parties. In order to establish the material terms, a Court may look at all relevant documentation and may hear oral evidence. It will resist “writing the agreement”"

Jan 1, 2003

A series of petrological studies were carried out on the characteristics of alteration and mineralisation in mainly structural-controlled (Deep Star, Meikle, Deep Post) and predominantly lithological-controlled (Post-Betze-Screamer and West Leeville) gold deposits in the northern district of the Carlin trend, Nevada. Alteration and mineralisation in these deposits are hosted in a sequence of calcareous clastic units of the Devonian Popovich Formation, into which have been emplaced a number of Jurassic intrusions, and syn- to post-mineral Eocene dikes. Four hydrothermal events have been recognised in these deposits: an initial Devonian base metal system and early diagenesis; a Mississippian stage of alteration in conjunction with burial metamorphism; contact and hydrothermal alteration and base metal-gold mineralisation associated with the emplacement of the Jurassic intrusions; and a Carlin-style gold system related to Eocene magmatism.

Jan 1, 2004

By F. S. LOTT, I. S. CULVER

The number of petroleum refineries in the United States decreased during 1948 from 390 to 375, continuing the trend to fewer units of larger individual capacity that has persisted since the peak in number of plants was recorded on January 1 , 1936. Large - scale construction of new processing facilities continued through 1948 with a resultant gain in daily crude-oil throughput capacity of installed equipment from 6,034,252 barrels on January 1 , 1948 to 6,438,995 barrels on January 1 , 1949. The capacity of the average refinery to process crude oil therefore increased during 1948 from 15,472 barrels daily to 17,171 . The principal areas of expansion of facilities were the strategic seaboard districts of the Texas and Louisiana Gulf Coast and the East Coast , and the important Indiana , Illinois , Kentucky, etc. , district that supplies markets in the upper Middle West region . These four districts accounted for 79 percent of the total new capacity added in the United States in 1948. The relatively small petroleum- refining industry of the Other Rocky Mountain district experienced a vigorous expansion in 1948 that will continue during 1949 . Capacity building on January 1, 1949 , amounting to 341,500 barrels daily, was 25,750 barrels lower than the comparable total on January 1 , 1948, but was the second highest on record . New construction was heavily concentrated in the Texas Gulf, East Coast , and Indiana -Illinois

Sep 1, 1949

By George D. Dub

The Bureau of Mines, in connection with the investigations of war minerals it conducted, examined the graphite deposits of this country, studied the methods of mining and preparation used, and sought to devise more efficient methods for the preparation of domestic graphite, and to standardize the quality of the product. The graphite investigations covered three general phases, as follows: 1. An examination of the deposits in Alabama and other States, and a survey of the methods of mining and preparation used. In this connection methods of sampling and analysis were noted and experiments made to determine a standard method of sampling and a, rapid but accurate method of analysis. 2. Experimental work on the concentration and refining of domestic crucible graphite to improve the quality of the product and to lessen waste. 3. Experimental work in crucible manufacture to determine the properties of domestic flake and the maximum proportions that might be used without impairing the quality of the crucibles. This work was accompanied by photomicrographic study of crucible structure.

Jan 1, 1920

By H. J. Ramey, I. S. Bousaid

Experimental results on the oxidation reaction kinetics in the forward combustion oil recovery process are presented. A total of 48 runs were made wherein a stationary thin layer of coked, unconsoli-dated sand was burned isothermally in a combustion cell. Individual runs were made at various temperature levels to permit determination of the effect of temperature upon the reaction. An expression was obtained for the burning rate of carbon as a function of carbon concentration, combustion temperature and oxygen partial pressure. The carbon burning rate for two types of crude oil indicated a first order reaction with respect to both carbon concentration and oxygen partial pressure. The effect of combustion temperature on the reaction rate constant matched the Arrhenius equation. The activation energy was similar for the two crude oils examined. The activation energy decreased for a porous media containing clay. The rate of oxidation of crude oil at reservoir temperature was found to be significant. Other significant findings included information on hydrogen-carbon content of fuel residues, fuel reactivity and the products of combustion. INTRODUCTION The production of crude oil by underground combustion has been studied in the laboratory by many investigators.1-5 Results of laboratory and field experiments have been reported in the literature describing the forward combustion process. But as yet, no qualitative or quantitative study of the kinetics of fuel combustion involved in this process has been reported. The fuel concentration and the rate at which fuel is burned at the front are important factors governing the air requirement in a forward combustion operation. Although the fuel is essentially unrecoverable crude, the air required to burn the fuel is an important economic factor in this process. Because fuel is burned, the heat transport associated with forward combustion is a key and unique feature of this new oil recovery method. Many investiga-tors5-9 have presented information on the heat transmission and fluid mechanics involved in forward combustion. Berry and Parrish10 demonstrated the utility of considering reaction kinetics in reverse burning. From differential thermal analysis, Tadema11 presented a qualitative discussion of the nature of reactions between oil and oxygen in combustion oil recovery. Although little quantitative work has been done on the reaction kinetics involved in forward combustion oil recovery, an extensive literature does exist on combustion of carbons and oils, and carbonaceous residues from cracking catalyst pellets. Dart, et al., 12 studied the combustion rate for oxidation of carbonaceous residues on clay catalyst pellets, and found the reaction to be second-order with respect to carbon concentration, and first-order with respect to oxygen partial pressure for carbon concentrations less than 2 weight percent of the catalyst weight. The reaction appeared to be first-order with respect to carbon concentration for concentrations greater than 2 percent. Metcalfe13 noted that other workers had found that aging of the fuel during the combustion process was responsible for changing coke properties, and it accounted for the apparent second-order carbon concentration effect found by Dart, et al. It appears that burning of residues from cracking pellets is first-order with respect to both carbon concentration and oxygen partial pressure. Dart, et al., also observed that hydrogen in the hydrocarbon residue appeared to react faster than the carbon. Lewis, et al.,14 studied oxidation of charcoal, coke and graphite in a fluidized bed. Gas velocities were high enough to partially lift and circulate the carbon particles. Their results indicated first-order reaction dependency with respect to both carbon concentration and oxygen partial pressure. One

Jan 1, 1969

By Roy H. Paddon

This paper describes the 6, 000 tpd, three stage haulage system at the Ozark Lead Company's mine in southeastern Missouri. It details the methods and problems pertinent to the loading, hauling, sorting, crushing, storing and hoisting of waste rock and ores obtained from underground development headings and production areas. The Ozark Lead Company is a wholly owned subsidiary of the Kennecott Copper Corporation. Its mine is located nine miles south of Bunker in Reynolds County at the south end of the "New Lead Belt" mining district. Development started in May, 1964, by drilling a seven foot diameter (six foot cased), 1, 250 foot development-ventilation shaft. Drifting began in August, 1965, to obtain a bulk ore sample, to test ore continuity, and to drive two mine levels while the pre-grouted production shaft was being sunk. Over 7, 900 feet of 12 by 24 foot drifting was done from this small shaft. In March, 1966, a 20 foot diameter, three compartment, concrete lined production shaft was collared. It intersected existing development headings at a depth of 1, 195 feet in April, 1967, and was completed along with a concentrator and other facilities in June, 1968. Mine production began that month, with 5, 000 tpd reached in 1970.\

Jan 1, 1971

By H. L. Burmeister

This report describes the mining and milling practices used by the Eastern Magnesia Talc Co. at its Johnson, Vt., operation. The report also contains a description of the local geology and all available information on cost and performance data. Since 1925 the mine has produced continuously at an average annual rate of 54,000 tons, and the ratio of ore hoisted to finished product is roughly 2 to 1. Ore is stoped by a combination of shrinkage and sublevel methods. In any 24-hour period the mill produces an average total of 14 grades of finished talc product, 9 by dry grinding and air classification and 5 by wet grinding and flotation methods. The mine operates one shift per day, 5 days per week and the mill operates on a 3-shift, 5-1/2-day-per-week basis. Operating costs for 1958, on a percentage basis, were mining, 22.34; milling, 54.77; ore haulage, 2.89; and all other, 20.00 percent.

Jan 1, 1963

By B. Meddings, O. J. I. Evans

"This paper is mainly concerned with the present and probable future role of hydrometallurgy in the production of base metals.The economic and technological bases of the hydro-metallurgical plants built and operative in the mid-fifties are compared to those in production in the mid-sixties. The trends observed are extrapolated and some estimates made concerning the probable size and type of hydrometallurgical plants which will be operative in the mid-seventies.The impact of emerging socio-economic factors such as pollution control and the market demand for specialized metal products which favour hydrometallurgical recovery processes are also discussed."

Jan 1, 1971

By Michael J. Klishis

Accident rates continue to show that underground mining jobs areamong the most hazardous occupations in the United States and roof bolter operators continue to have one of the highest accident incident rates (MSHA, 1991) despite efforts by labor, government, and industry to reduce and eliminate work-related hazards. In the last two decades we have seen technical innovations such as the ATRS, and there has been an increased emphasis on hazard awareness through programs such as MSHA's REAP, but bolter operators continue to be injured and killed. Researchers at West Virginia University examined risk in the roof bolter's job and developed new approaches to accident and injury prevention. The study concentrated on the workers' job performance, machinery and the work environment to identify miner's risk and hazard exposure while bolting.

Jan 1, 1993

By V. M. Benson

A simplified, routine method for determining lithium in lithium-bearing rock is presented. The sample is decomposed by repeated treatments with nitric, hydrofluoric, and perchloric acids. Since this procedure does not appreciably dissolve beryl, interference by beryllium (the principal interfering cation) is minimized for most samples. The salts are brought into solution with water and enough citric acid-ammonium citrate buffer is added to make the final volumetric dilution 0.20 M with respect to citrate. The addition of citrate greatly reduces anion interference in the hydrogen-oxygen flame, slightly increases the intensity of the lithium 671 millimicron emission line, and reduces the effect of most of the interfering cations to the extent that analytical separations are not necessary. The accuracy of results of single determinations of lithium in a pegmatite containing spodumene, lithium-bearing mica, and beryl are approximately equal to that obtained by other flame methods, INTRODUCTION This investigation was undertaken in Bureau of Mines laboratories to develop a reliable, rapid, routine analytical method for determining lithium in lithium-bearing minerals. The requirements of the procedure were that the method should be applicable to the analysis of a variety of lithium-bearing ores and test products, and the results would be reasonably accurate for materials containing 0.05 to 8 percent Li20.

Jan 1, 1961

By Dr. -Ing. Wolfgang Pietsch

Many primary metallurgical wastes are in the sh.-ape of turnings; borings, chips, dusts, and other particuletes. While such. materials can be easily segregated and/or upgraded to yield high quality ?secondary metals with often known composition for easy recirculation into the production? process; their particulate nature results in various problems. Roller presses are used in an ever increasing number for size enlargement and densification of primary particulate metallurgical wastes for secondary metal recycling. The paper will mention the areas of application from A(luminum) to Z(ink), also including Brass; Cast Iron, lead, and Stainless Steel, as well as dusts from all types of melting and ladle furnaces or converters. Typical systems using roller presses for size enlargement. will be discussed.

Jan 1, 1995

By R. Guardia, J. Hoskins, E. Claros, Y. Kamiya, R. Ramirez, J. Dalenz, P. Fernandez, E. Ilgren

Crocidolite is a well known causative agent for mesothelioma. Studies have shown that the pathogenicity of the fiber from different mines varies considerably and it has been postulated the parameter that appears most likely to account for this variation is fiber width. Epidemiological studies have shown that ‘thin’ fibers from mining areas of Western Australia and the Cape Province, in South Africa are associated with a high mesothelioma risk while exposure to ‘thick’ asbestiform amphibole fiber of the same fiber type are associated with little or no mesothelioma risk. This study is concerned with ‘thick’ Bolivian crocidolite but similar findings also probably explain the paucity of mesotheliomas in the Finnish anthophyllite, South African amosite and African Transvaal crocidolite mines. The findings from the present study suggest the incidence of mesothelioma in the three major cities of Bolivia is not significantly elevated above background even though Bolivian crocidolite has been used for the past 60 years commercially and residentially in all three cities. Although some cases of mesothelioma may have been missed due to a failure to reach hospital or a shortened natural lifespan, mesothelioma generally occurs after the age of 50, we cannot tell precisely the extent to which these were confounding. We suggest the most likely explanation for the lack of mesotheliomas despite the large populations at risk from the long and extensive residential and commercial use of crocidolite containing products, is related to an increased fiber width distribution and a concomitant reduction in the ‘Stanton fiber size’ fraction.

Jan 1, 2012

By James C. Foley, David K. Rehbein

"In-situ characterizations of green state part density and sintering state have long been desired in the powder metal community. Recent ·advances in non-contact electromagnetic acoustic transducer (EMAT) technology have enabled in-situ evaluations of the acoustic attenuation and velocity as sintering proceeds. Pure aluminum (99.999%) and aluminum alloy powders were prepared with high-pressure gas atomization (HPGA). The powders were pressed in a uniaxial die and examined with acoustic waves for changes in velocity and attenuation during sintering. The changes in acoustic properties were correlated with sample microstructures and mechanical properties. Evolution of the acoustic echo train during sintering is shown to provide information on the state of sintering as well as having the potential for detection of interior flaws.IntroductionThe versatility of powder metalallurgy (PIM) technology in the manufacture of complex shapes has enabled an increasing amount of wrought and casting production capacity to be converted to PIM technology. However, ultrasonic inspection of green components produced using PIM techniques remains a challenge and is not generally practiced [1]. Inspection of PIM components in the green state is highly desirable, because the green part can be reclaimed with only accepted components being subjected to further costly processing. Another potential benefit is characterization and greater understanding of the sintering process itself. An increased scientific understanding of the sintering process enables intelligent process control, greater reliability of the production process and a lower rate of rejection of the finished product. In order to realize these potential benefits, it is necessary therefore that accept/reject criterion be based on real time nondestructive evaluation of the green-state components and the sintering process.Most current nondestructive inspection techniques suffer from their inability to perform inspections below the near-surface region with the exception of X-ray and to some extent pulsed eddy current [2]. X-ray inspection requires extensive shielding of production personnel and expensive film and film processing. While development of pulsed eddy current techniques have lessened the impact of the well-known skin effect, the depth of penetration of the induced eddy currents remains somewhat of an issue [2]."

Jan 1, 2000

By F. O., Garrabrant

ELECTRIC power requirements for Climax are similar to those of most metal mines, except that large blocks of power are used underground and there are a number of other unusual applications. Power is furnished to the Company by the Public Service Co. of Colorado over two 100,000-volt lines to a bank of three 3333-kva. transformers 100/13.8 kv. These transformers are designed so that with the addition of forced cooling their capacity may be increased a third at 12,000-ft. altitude. On the secondary side of this bank is a 15-kv., 1200-amp. oil circuit breaker provided with automatic reclosing relays allowing three successive short circuits before lockout. From this breaker 13.8-kv. power is transmitted to a central switching station where all circuits radiate to the different operations of the property. Each circuit is protected by a 23-kv., 600-amp. oil circuit breaker with by-pass and isolating disconnecting switches. (A more complete description of the electrical distribution system at Climax, with detailed drawings, is contained in T.P. 1734, A.I.M.E., Mining Technology, July, 1944.)

Jan 1, 1946