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Create two air splits along the longwall face to isolate the shearer-generated dust to the immediate face area, maintaining a cleaner split of air in the workers' walkway.

Jan 1, 1994

By D. K. Dysinger

Capital resource budgeting is the means by which managers of publicly held companies fulfill their fiduciary responsibility to maximize the wealth of stockholders. Managers maximize shareholder wealth by allocating investment capital to the most productive of competing alternative projects in a manner that maximizes the net present value of the firm's future cash flow. The techniques of cash flow analysis are the primary tools available for selecting a corporate portfolio of projects that meets or exceeds the rate of return expected by shareholders. The reliability of cash flow analysis hinges on the ability of managers to forecast the future values of individual components. The accuracy and reliability of forecasting determine the soundness of capital investment decisions and, ultimately, determine the value of the firm. The present paper will explore tools for forecasting the spot market price of a commodity, silver, to demonstrate the difficulty and uncertainty involved in forecasting the future. The commodity price is only one of a number of components of the cash flow equation. Each component has a unique and uncertain future and must be individually analyzed and forecast to arrive at a robust cash flow model.

Jan 1, 1997

By D. A. Norrgran

The recent development of rare earth permanent magnets has revolutionized the field of magnetic separation. The advent of rare earth permanent magnets in the 1980's provided a magnetic energy product an order of magnitude greater than that of conventional ferrite magnets. This has allowed the design of high-intensity magnetic circuits operating energy free and surpassing the strength and effectiveness of electromagnets. New applications and design concepts focused on the mineral and metal processing industries have evolved. This technology also led to the development of various magnetic separators specifically designed for mineral processing applications. Applications which were not previously considered are now being applied to primary mineral upgrading and recycling and secondary recovery.

Jan 1, 1993

By Ormsby W. R, Farrar L

The stratigraphy of the central Pine Creek Geosyncline has been simplified into a three-fold subdivision comprising the Batchelor, Frances Creek and Finniss River Groups. The Batchelor Group consists of a sequence of shallow water coarse clastics and crystalline carbonates and is conformably overlain by the marine carbonaceous shale dominated Frances Creek Group. Interbedded within the carbonaceous shale are turbidites, iron formation, tuffs, carbonate and non carbonaceous shale. The Finniss River Group is a flysch sequence of greywacke and mudstone. The stratigraphic and structural evolution and igneous history are all interrelated. Although the Batchelor Group may have formed in a tensional regime, it is likely that regional compression and accompanying thin skinned deformation began during deposition of the Frances Creek Group. Continued compression resulted in D2 folding d6collement deformation, wrench faulting in compressional zones and thrust faulting. Occasional relaxation of compression is marked by a number of periods of basic intrusion and perhaps distal volcanism. The style of deformation within sediments varies away from granitic basement highs and is similar to that observed around salt domes and found in experimental diapiric models. Sedimentary facies changes also indicate local emergence of basement highs during sedimentation. As compression continued, the deposition of thick sequences of the Finniss River and El Sherana Groups brought about regional metamorphism. Relaxation of compression and waning of associated subsidence resulted in a relative increase in the rate of uplift and partial melting of diapiric sialic basement. In places, granitic magma moved upwards and crystallised forming grossly concordant bodies. Other masses moved laterally and formed extensive granitic sills. Later compression periods caused mainly brittle deformation which may have been strongly influenced by underlying basement fabric.

Jan 1, 1994

By Noel A. Warner

Modern steelmaking is based on direct use of oxygen in high intensity batch reactors. A totally new approach is proposed in this paper, based on the view that pursuit of high intensity is unlikely to lead to successful coal-based continuous steelmaking. By substituting carbon dioxide and water vapor as the oxidants rather than using oxygen directly, the intensity is greatly reduced. Accordingly. subsurface formation of carbon monoxide bubbles can be avoided by careful manipulation of the three participating rate processes, gaseous diffusion, interfacial chemical kinetics and liquid phase mass transfer. Steelmaking can then be carried out without explosive ejection of molten droplets and the generation of micro-spray but rather in a controlled and fumeless fashion. The vital component is the introduction of generic melt circulation technology. Three melt circulation loops in series are envisaged. Starting with a composite feed of iron ore fines, pulverized coal and lime flux, a metallized solid raft floating on molten iron is propelled out of the ironmaking loop onto the first of two downstream steelmaking loops. In the first, a liquid slag is formed, primary decarburization is undertaken not with oxygen but rather with CO2 and H2O and the melt is desulfurized. The semi-product stream enters the third melt circulation loop, where open-channel decarburization is effected along with dephosphorization to yield a low carbon steel product. Alternatively, the melt leaves the last loop to irrigate a packed tower countercurrent to argon at around 100 mbar to continuously produce ultra-low carbon (ULC) steel.

Jan 1, 2003

By U. Steiner

Electronic detonators have been in commercial use for a decade, with an excellent safety record. This paper lists known incidents involving electronic detonators. Typical standards required by regulatory bodies for static electricity and electromagnetic fields are reviewed. The performance of some detonators is compared to these standards; in general the minimum standards are easily exceeded. The general resistance of electronic detonators to extraneous electrical energy that can be derived from the body of test results is compared to danger levels for exposure of humans to these energies; it is shown that electronic detonators can safely tolerate higher electrical energies than people can. This comparison includes comparable data for electric detonators, which are shown to be more vulnerable to extraneous electrical energy than people are. Electronic detonators also bring significant safety benefits in blasting due to their testability, two-way communications, reliability, programmability and precision. The links between these attributes and enhanced safety are discussed with examples from actual blasting. Although electronic detonators are usually more vulnerable to extraneous electricity than non-electric initiation systems, the paper shows that the net safety benefit in handling and blasting is in favor of electronic detonators, which are the safest initiation system that has ever been offered to the mining industry.

Jan 1, 2010

By Erick Lino

Como parte del proceso extractivo de la minería, se generan materiales de desmonte que deben ser almacenados en topografías bruptas y planas dependiendo de la capacidad de almacenamiento que requiera el proyecto. La geometría y los taludes de estas estructuras deben ser diseñados tomando en cuenta las propiedades de resistencia del desmonte de mina. Por ello, el presente texto describe la importancia de la caracterización geotécnica de este material con el objetivo de diseñar el depósito de una unidad minera en condiciones estáticas y dinámica.

Feb 1, 2017

By Sharif Jahanshahi

Calcium ferrite slags are often associated with Professor Yazawa due to his pioneering work on the thermodynamics of this type of melts. Over the past years CSIRO has invested some effort in studying physico-chemical properties of such melts to fill in some gaps in our knowledge and explore opportunities for application of the understanding developed. These investigations cover thermodynamics, transport properties of calcium ferrite based slags, as well as the kinetics of reactions of such slags with refractories. The present paper provides an overview of some of these studies and highlights some of the interesting behavior of such melts. The oxidation state of copper and arsenic in calcium ferrite based slags are predominantly Cu+ and As3+, respectively, at oxygen potentials below 10.1 atm. The concentration ofCu2+ in such slags becomes significant at oxygen potentials of greater than 10'1 atm at 1300 ?C. The activities of CuOo.s and AsOl.S in calcium ferrite slags show strong deviations from the Raoultian Law, while that of CoO is very close to ideal behaviour with respect to pure solid CoO. Addition of Si02 to calcium ferrite slags can have significant effects on the activities of FeO and Fe2O3 and hence the stability of magnetite phase. Transfer of oxygen in calcium ferrite slags is fast with diffusivity of 2xlO?3 cm2/s at 1350 °C and activation energy of 16 kcal/mol Presence of solid phases, such as magnetite, has pronounced effect on the viscosity of calcium ferrite slags. The observed dependence on solid loading and shear rate indicates deviation from Newtonian behaviour. The interfacial tension between copper mattes and calcium ferrite slags is strongly dependent on the matte grade, with the determined values being much lower than the corresponding ones for interfacial tension between similar mattes and iron silicate slags. MgO, Cr2O3 and MgCr2O4 have low solubility in calcium ferrite slags and their solubility increases with increasing copper oxide content of the slag at 1300 °c. The oxidation state of the slag has strong effects on phase transformation, dissolution rate and disintegration of refractories in calcium ferrite slags. Other key factors with major impact on slag-refractory interactions include viscosity and surface tension of slags as well as the contact angle between slag and refractory material.

Jan 1, 2003

By Donald A. Cumming

Since the first major mine development, the company has continually looked for ways of improving drifting methods. The planned increase in production to 60,000 tpd, and the lack of trained personnel, requires new development methods to maintain this high production rate. In order to finish the drifting on the 2015 and 2075 levels, a total of 59,000 ft is required, or two years at the present rate.

Jan 4, 1972

By John M. Hird

Texas Gulf Sulphur Company's Lee Creek Mine has opened a major phosphate mining district in the Central Coastal Plains of North Carolina (Fig. 1). The ore deposit as it is now known was roughly outlined in 1961 by a Texas Gulf geologist using wire line exploration methods. Slightly uraniferous phosphate materials were detected by a slim-hole gamma ray probe run in numerous farmers' water wells penetrating the formations. A follow-up-core drilling pro- gram determined the economic ore limits to lie in the south central section of Beaufort County beneath 70 feet to 120 feet of unconsolidated sediments. The 50,000 acre deposit is known to contain over two billion tons of phosphate ore amenable to strip mining methods. A part of the deposit underlies several thousand acres of the Pamlico River estuary. The 90 million dollar capital investment plant built by Texas Gulf during 1965-66 included a strip mining operation using a 72-yard walking dragline, a three million product ton per year flotation concentrator, four fluid bed calciners, a sulphuric acid plant (acid for captive use), a phosphoric acid plant, and three solid fertilizer material plants. Shipment to domestic markets is by rail and truck and to over- seas markets by barge to a transshipment terminal at Morehead City, North Carolina. Early mining investigations were conclusive first that the phosphate ore could economically be recovered only by dry strip mining methods, and second that artesian ground waters in the formation (Castle Hayne limestone) underlying the ore would have to be controlled. This report will relate the application of ground water hydrology in depressurizing the Castle Hayne aquifer to facilitate dry strip mining at depths 130 feet below sea level at the Lee Creek Mine.

Jan 1, 1970

By Kamalendu Bhunia

With the progressive depletion of known resources of good quality coal and minerals as well as the increasing demand of these minerals by different user industries, the emphasis has been shifted all over the world from selective mining to bulk mining followed by up- gradation to obtain the required quality of concentrate. The column flotation cell is one of the alternatives to reduce the gangue content of fines because of its inherent characteristics viz. easier to operate, low space required, no moving parts etc. A laboratory flotation column is used to conduct experiment. Present work has been undertaken to observe the effect of process variables (gas flow rate, feed/slurry flow rate, and frother concentration) on gas dispersion parameters (gas holdup, bubble surface area flux) in collection zone and to explore the effect of feed (slurry) inlet orientations and gas flow rate on column?s metallurgical performance. The effects of solid particle concentration, size and type (hydrophobic and hydrophilic) of solid on gas dispersion parameters have also been investigated. Test work has been performed in a continuously operating Perspex column (10 cm in diameter and 168 cm in height) using coal, sphalerite and dolomite as solid. Gas hold-up has been measured by phase separation method and mean bubble sizes are estimated from a drift flux analysis. The influence of operating parameters on bubble surface area flux has been discussed. It is observed that gas holdup in collection zone is affected by air as well as feed flow rates and also solid?s type. It is also found that addition of solid decreases the gas holdup and rate of decrease in gas holdup increases when solid concentration increases and particle size increases. Increase in gas flow rate increases recovery in collection zone due to increase in number of bubbles per unit volume of the column. From the experimental results it is evident that cross-current orientation of feed inlet shows slightly better metallurgical performance compared to other orientations. Keywords: column flotation, gas holdup, drifts flux, bubble size, bubble surface area flux, hydrophobicity, and recovery

Sep 1, 2012

By Andre Journel

El presente texto describe el origen, clasificación y la estructura de la geoestadística en el campo de la minería. Para ello, se describe primero la función de la estadística como materia de conocimiento económico y de estimación minera. Esta misma se divide en estadística variable dependiente y a su vez en Krigeage universal, estructura variable regionalizada y la morfología matemática. Mientras que la geoestadística tiene una función estructural más simple, donde su extensión es aplicable es a todo tipo de variable regionalizada como la ley en mineral, potencia o espesores, profundidad submarina, salinidad media en una zona, densidad de población, valor de gen un punto o en una zona, cantidad de lluvia en cm², etc.

Nov 20, 1969

By A. Bastrzyk

Text The mining and refining of minerals generates large amounts of solid waste. The waste from cleaning operations constitutes up to 90% of the total production. Although some of them can be used in mining, civil enegineering, construction, agriculture, most of them must be disposed in dumps and slurry ponds, causing major economic and enviromental problems (Alonso, 2002; Alon-so, 1999). The refuse from minerals cleaning may have considerable valuable particles content, which can be used in industry. Thus, the recovery of these particles from minerals waste by using a cleaning method effective at fine particle size, may overcome these consequences. Surfactants are used in numerous applications including emulsification and solid surface modification. In the oil agglomeration of minerals, the ionic surfactants (both anionic and cationic) are used for the hydrophobization of mineral surface and the oil-water emulsion preparation. When the cationic surfactant is injected into the oil-water mixture, surfactant molecules adsorb at the oil-water interface, changing droplets? properties. The addition of anionic surfactant to the mineral suspension was found to modify the solid-liquid interface. In this paper, the condition and mechanism of selective separation of magnesite from quartz are presented. A satisfactory was achieved with the amount of anionic collector (sodium oleate) equal to 15.2 mg/gsolid and with the amount of cationic collector 27.9 mg/gsolid for cetyltrimethylammonium bromide (CTAB) and 16.9 mg/gsolid for dodecyloammonium hydrochloride (DDAHCl) at pH 8. At these conditions, the amount of agglomerated carbonates was about 12% for CTAB and 5% for DDAHCl.

Jan 1, 2014

By J. F. Messerly

The purity of three specially prepared samples of benzene was determined with an adiabatic, low-temperature calorimeter with automatic control of shield temperature. Extensive measurements were made on each sample to determine how variations in operating procedures affect melting-point and freezing-point as well as purity data obtained by the calorimetric method. Detailed results of the investigations are presented, and effects of different operating procedures are discussed, together with problems encountered in interpretating experimental results.

Jan 1, 1963

By D. Harrington

"The recent discovery and exploitation of petroleum territory have resulted in the enactment of new petroleum laws in most of the South American Republics. The activities in the discovery of these new fields were engendered by the knowledge of the fact that present producing fields must within well defined periods be exhausted. Oil operators were willing to take the initial steps in exploitation in the absence of legislation that applied strictly to petroleum operations. The enactment of modern legislation in many of these Republics encouraging and protecting exploitations may cause tremendous oil activities in these countries, and the results may be comparable with the magnitude of the undertakings and the prestige of the companies now entering this territory.These, oil fields are admirably located for convenient distribution of petroleum by water to all the Nations using oil as fuel for shipping and industrial concerns. The oil markets of the western coast of South America will derive immense benefits from the Panama Canal. This navigation route brings these markets into direct ocean shipment with the Atlantic coasts of the Western and Eastern Hemispheres.One deterrent to oil production in the Republics of South America is the want of inland. transportation facilities, but the recent laws of these Republics without exception provide for acquiring rights of way for pipe lines and other modes of transportation; and doubtless the great interests and. syndicates already operating in these regions will, as production increases, provide ample pipe line transportation sufficient to convey to the coast the oil produced. It way be assumed, from the legal guarantees afforded, and from operating equipment and machinery that are now being concentrated that refineries will be erected at shipping points for the purpose of making these petroleum products accessible to the world."

Jun 1, 1921

By J K. Irwin

The authors discuss the application of drum and friction hoists under modern conditions and give four examples of friction hoists proposed for various applications. The paper concludes with a summary of the advantages and limitations of friction hoists relative to drum hoists. Introduction T H~ introduction of the multiple-rope friction hoist m the late 1940's has complicated the se-lection of the right hoist for a given job. Once such considerations as rope safety factor, drum to rope ratio, hoisting distance, tons per hour and/or service duty have been decided upon, the selection of a drum hoist is relatively simple. We now ask our-selves "which hoist -drum or friction? (See Figure 1 and Figure 2). When a friction hoist is a possibility we are immediately concerned with how many ropes to use, whether to hoist balanced or counter-balanced, whether a friction hoist will be flexible enough for the application and, of course, what the relative costs will be.

Jan 1, 1964

By Gregg PEH, Stewart RB

Reclamation field trials commenced in 1985, two years before the granting of the Mining Licence. The level of pasture production on varying soil depths (0 cm, 5 cm, 15 cm and 25 cm) overlying both tailings and oxidised waste overburden was assessed. After seven years, the rate of increase of N, C, P and S, losses of S and P and pH changes were investigated on the plots where grass seed was sown into bare tailings. It was determined that on these plots it would take approximately 24 years to reach the original carbon and nitrogen levels at the mine site.

Jan 1, 1995

By Henry C. Freeman

During the early period of the construction of the Illinois and Michigan Canal, about 1838, in excavating for the canal, where the present town of Utica stands, hydraulic limestone was discovered, and its value was recognized. A kiln for calcining and a mill for grinding were erected, and the cement was used in the construction of the locks of the canal. This property was subsequently bought by the present owner, Mr. James Clark, and the work has been continued to the present time in much the same primitive manner as it was begun. The bed is exposed in the Illinois River valley by stripping off a few feet of the covering rock. It is from 4 feet to 6 feet 9 inches thick, and nearly level, dipping gently to the northeast. The Utica Cement Company's establishment, which is two miles west of Utica and two miles east of La Salle, was an outgrowth of the Illinois geological survey. The writer was in charge of the district which included La Salle county, and, in working out the details of the geology of that county, discovered, below the Utica bed, another workable hydraulic limestone, which makes its appearance in the northern bluff of the Illinois River valley, rising above the water level at the point where the company's works are established. This cement group, of which there are several thin beds, lies just below the St. Peter's sandstone, with a few feet intermediate of transition-rock, which appears to represent the Calciferous, and is exhibited in place, in concretionary form, at the top of the bluff. The hydraulic beds are very regular, and the one worked by the company is 10 feet thick; or, speaking more definitely, there are two beds, separated by 18 inches of sandstone, lying about two feet above the bottom, and the two beds are worked as one, the sandstone being first cut out and removed, to prevent mixture. In 1869 I was invited to join with a company, and to take charge

Jan 1, 1885

By Harry Verakis

Flyrock is the second leading cause of all blasting related injuries in surface coal, metal and nonmetal mining operations. It is also a primary cause of property damage, monetary losses and “near misses.” For the period 1978 to 2008 flyrock accounted for 11.6 percent of all blasting-related injuries in surface coal, metal, and nonmetal mines. A large amount of published material has been published on the safety hazard of flyrock, on ways to predict how far rock will travel from a blast, as well as ways to protect mine personnel and neighbors from flyrock. However, flyrock incidents continue to occur resulting in fatalities and “near misses” that could have caused fatalities. It was only good fortune in some instances that no one was in the mine's parking lot or other unprotected area when flyrock rained down or in harm’s way when a large rock punched a hole in the roof of a building or other structure.

Jan 1, 2011

By Franklin Moeller

CONSIDERING the really short time that has elapsed since hydro-metallurgical processes of extracting copper from ores have been extensively developed, and the large scale on which this method is practised at Ajo, the successful operation of the plant must excite the admiration of every visitor. The application of the mechanical unloader to the purpose for which it is employed at Ajo is but an extension of the use for which it was originally designed, some 20 years ago, for unloading iron-ore vessels at the lower lake ports. At a time when the maximum output of a single machine, with men shoveling the ore into buckets, did not exceed 40 tons per hour, G. H. Hulett invented and constructed a mechanical unloader with a bucket of 10-ton capacity. This machine was of the steam hydraulic type, and it is still in operation after nearly 20 years of service. Several more machines of the same type were built, but the difficulties of power transmission, and the rapid development of electrical machinery, soon led to the adoption of electrically operated machines, and practically all of the later installations have been thus equipped. This electrically operated unloader has proved so well fitted for the work that the design of the lake boats has been practically revolutionized, with special view to the ease and rapidity of unloading. It is now possible to unload a 12,000-ton vessel with four machines in a little over 2 hr. This has necessitated an increase in the capacity of the machine, and the largest yet built handles an average load of 17 tons, with a possible maximum of 20 to 21 tons.

Jan 8, 1918