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By I. A. Mwamba

Titanium aluminide of composition Ti-47.5 at.% Al was prepared by melting titanium and aluminium of commercial purity with additions of precious metals of 0, 0.2, 1, 1.5 and 2 at.% content. The microstructure, hardness and oxidation properties were assessed. It was found that at 47.5 at.% Al, the microstructure of plain TiAl alloys was duplex, consisting of duplex lamellar grains and ? grains. The lamellar grains consisted of alternating lamellae of ? (TiAl) and a2(Ti3Al), with overall aluminium content in the range of 43?47 at.%. The ? grains had a aluminium content above 50 at.%. The addition of precious metals to the TiAl alloy resulted in the formation of a new phase, with a high precious metal content, occurring mostly in the ?phase, without any major change to the microstructure. Increasing the amount of precious metals resulted in an increase of the new phase amount, at the expense of the ? phase. The hardness of the different alloys was around 300HV10. Overall, the research has shown that addition of precious metals to TiAl resulted in a slight increase in hardness and a significant improvement of the oxidation resistance. This shows that alloying TiAl with precious metals, at the addition levels investigated, does not alter the mechanical properties very much, but improves oxidation resistance.

Jan 1, 2012

By Willie M. NeSmith

Conventional augered, cast-in-place (ACIP) piles were introduced into the New York City area as a result of the damage to existing structures caused by pile driving operations. ACIP piles are often specified where deep foundations are to be installed adjacent to transit facilities, sensitive underground utilities or in close proximity to existing structures. However, loss-of-ground issues associated with the installation of ACIP piles have prevented the wide-scale use of these systems. Beginning in 2002, Berkel & Company Contractors, Inc. began using its augered, cast-in-place displacement (ACIPD) system in the New York City area. Like conventional ACIP piles, this system produces almost no vibration. Also, as almost no material is brought to the surface, there is no opportunity for loss of ground. This paper presents a description of Berkel's displacement pile system and a brief discussion of six projects in the New York City area that have been executed with this system over the past two years.

Jan 1, 2004

By Luis Alberto Medina

La característica principal de la composición de un cuerpo mineralizado es la heterogeneidad, dado que sus elementos no son iguales. En ese sentido, la prueba de heterogeneidad en el mineral de Cerro Verde, es una guía para la geología, mina, metalurgia y laboratorio químico, que busca optimizar los protocolos de muestreo y minimizar errores en las muestras tales como: Error Fundamental; Error de Segregación, generado por una muestra o submuestra cuando es cuarteada; Error de Extracción, generado por una muestra pequeña o insignificante colectada o tomada, y Error de Preparación, producido por la pérdida excesiva de finos. De acuerdo al estudio, el presente trabajo señala que la heterogeneidad de cobre total, cobre soluble en ácido y cobre soluble en cianuro, desarrollada para el mineral de Cerro Verde, es baja, lo que permite un manejo operacional sencillo para el muestreo con protocolos más simples, mientras que el parámetro más heterogéneo es el cobre soluble en cianuro y el protocolo podría ser afectado en el error fundamental.

Sep 13, 2001

By D. A. Reynolds

[A few studies on the relationship of the fusion temperature of the ash of coke to that of the corresponding coal have been made on commercial high-temperature cokes. R. J. Rose3/ in 1921 compared the' fusion temperatures of the ashes of 10 coals and. the cokes produced from them and concluded tat they were in such close agreement that either figure could be used. More recently, Quarfort4/ found that the ash of coke fused at a somewhat lower temperature than that of the original coals As the ash of a coal and that of the coke produced therefrom have the same origin their chemical composition should be identical, provided that carbonization has not altered the inorganic, or ash-forming, constituents of the coal, and such alteration seems highly improbable. However, it has been shown5/ that coke is liable to contamination by iron during crushing and preparatory to sampling. Pieters6/ found that coke ash was cantaminated in this manner up to 0.4 percent. extraneous iron would lower the ash-fusion temperature because such iron may form ferrous silicate, which is readily fusible,7/ These results provide a basis for the prediction that the ash of coke will fuse at a lower temperature than that of the corresponding coil., especially if the fine grinding of the coke was done by rubbing surfaces of iron, as in a disk pulverizer or bucking plate.]

Jan 1, 1940

By Wesley Schmutzler

The Deep Mixing Method (DMM) was employed to raise and support the LPV (Lake Pontchartrain and Vicinity) -111 Levee in New Orleans. Even using innovative technologies, the tight schedule to achieve the 100 year elevation by June 1, 2011 was a daunting endeavor. The size and scope of DMM proposed for LPV-111 was on a scale never attempted outside of Japan. Over 1.65 million cubic yards of DMM was installed. LPV-111 is adjacent to the Bayou Sauvage Wildlife Refuge, which is the largest urban National Wildlife refuge in the United States. By utilizing DMM to control settlement and improve stability of the taller levee, side slopes were steepened from the conventional 1V:4H to 1V:2.85H, thus avoiding encroachment into the Bayou Sauvage and reducing the amount of clay needed for the completed levee. The COE utilized Early Contractor Involvement (ECI) for this contract. The ECI process allowed for input from the DMM contractor, TREVIICOS South, in order to optimize equipment resources and material requirements. This paper gives an overview of the extensive DMM requirements for LPV-111 and explains the benefits of the ECI process.

By Edward A. Barrett

The ability to recognize visual cues commonly associated with roof and rib hazards is fundamental to the prevention of groundfall accidents. The perceptual skills that miners possess to visually search and assess hazardous ground conditions differ considerably. This U.S. Bureau of Mines report summarizes recent investigations on the use of stereoscopic (3-D) slides as a training aid for improving the ability of miners to recognize the various geologic and mining-induced irregularities that cause ground-falls. The feasibility of using 3-D slides for training and their effectiveness for representing roof and rib hazard conditions are discussed. Information is presented on equipment and procedures for creating a 3-D slide program that can be updated by mine trainers. Recommendations are made on selection of 3-D equipment and on the use of 3-D slides for training miners to recognize roof and rib hazards.

Jan 1, 1988

Applicaton of Agricultural Residues from Pyrolysis in Flotation of Black Coal

Sep 13, 2010

By Harald Ludwig

In 2002, excavation support work commenced on the Capitol Visitor Center project located adjacent to the nation?s Capitol building in Washington, D.C. The outlying work (Slurry Wall Work at Main Site is not discussed) consisted of providing excavation support for a new truck tunnel approximately 1900 feet long up to 50 feet deep as well as support for the new underground auditorium and Library of Congress tunnel. The excavation support consisted of a combination of conventional drilled in soldier beams, lagging, tiebacks and braces; intricate underpinning inside the existing Capitol building; support of an existing Russell Tunnel; soil nailing and tiebacks underneath the existing Russell Tunnel; two temporary bridges; and a deep soil mixed wall with lateral support provided by braces. As part of an on-going research program, some of these braces were instrumented with strain gauges. The deep soil mixed wall was approximately 300 feet long and 65 feet deep on either side of the truck tunnel. Approximately 34,000 sf of deep soil mixed wall, 90,000 sf of conventional excavation support, 200 braces, and 320 tiebacks were installed. This paper describes the large scope and breadth of the project that required a variety of excavation support techniques. A few of the challenges in designing and installing the support of excavation are discussed. This paper also presents the results of the instrumentation program conducted on the deep soil mixed wall, which stood open for more than a year.

Jan 1, 2006

By Martin Smirlock

A novel instrumentation system has been developed which enables simple, quick, and accurate measurement of vehicular dynamics within low speed ranges. The system, consisting of a microwave transceiver and microprocessor data acquisition and reduction system, measures the deceleration dynamics of low-speed mining and construction equipment. It makes the basic measurement, calculates key parameters such as average deceleration, initial velocity, stopping distance, and brake system delay time, and produces autoscaled graphs of velocity, acceleration, and displacement versus time.

Jan 1, 1981

By Grant Loveday, Vincent Dieudonné, Andrew Jonkers

Bateman Minerals & Metals supplies the APIC Technologies which include the under-bed air-pulsed APIC jig and related technologies such as the JigScan controller and advanced mathematical models of the jig process. Bateman have developed a methodology for predicting process performance for jigs from simplified testing and modelling, based on batch equipment matched to industrial designs. Batch tests conducted on laboratory scale air-pulsed jigs can process small batches of material, such as those obtained from drill core samples. The novelty comes from using an advanced jig process model, ASTRAD, to link the results of batch and continuous jigs. The batch jig presented as a novelty in this paper has been designed to be hydraulically equivalent to the full-scale APIC Jig, allowing the generation of equivalent pulse shapes and using JigScan controller. Lump and fine ferrous ore material have been separated in this unit and any feed >1mm can be tested and extracted. The global test procedure and further modelling focus on the stratification of material, with emphasis on key aspects such as pulse shape, feed characteristics and residence time. The splitting of rejects from concentrates is itself more difficult to reproduce in batch jigging, however the ASTRAD model includes a separation imperfection module, and the APIC Technologies have extraction systems adapted to each type of material. Air pulsed batch jigs are available in several locations and are relocatable. They have been used to treat samples from Australia, South Africa and India as part of studies into ore processing using jigs. Each test layer is available for various physical testing procedures (density and chemical analyses). Test-work is performed on a case by case basis, and analysed using an advanced model ?now available over the internet. Some fundamentals of air-pulsed jigging are recapped along with some of the features of APIC jigs. The process of designing a ?hydraulically equivalent? batch jig test is then described. Some results from jigging tests are presented plus the results of the ASTRAD advanced jig model, which was first developed at the JKMRC with ferrous ores and coal and is now being supported and further developed and utilised by Bateman.

Jan 1, 2006

By SME SME

NORTH AMERICAN TUNNELING 2024 PROCEEDINGS

Jun 23, 2024

By Edward L. McHugh

The study area, which comprises 11,500 acres, includes the 9,610-acre Whitewater Wilderness Study Area, in the California Desert Conservation Area, 15 miles northwest of Palm Springs, CA. The U.S. Bureau of Mines evaluation of mineral resources is based on examination of prospects and mineralized areas during the spring of 1981. The Whitewater study area is mainly underlain by granodiorite to quartz diorite and their gneissic equivalents in an igneous-metamorphic complex. Late Tertiary sedimentary and volcanic rocks locally overlie the crystalline complex in the eastern part of the study area. The study area lies between branches of the San Andreas fault system.

Jan 1, 1986

This paper summarizes the results from a project aimed at adapting scroll centrifuges for application to the dewatering of flotation concentrates. The main impetus for the project was to reduce the high cost and footprint size of the technology currently used to dewater fine coal. The technical challenge was to enhance solids capture by incorporating a laser-cut screen into the design of the basket. The project has shown that a pilot-scale scroll centrifuge can be used to dewater froth concentrate. A number of different basket designs were tested, the best results being achieved with a basket comprising a laser-cut screen of aperture 70 µm. The best result on a sample of untreated flotation concentrate, which was taken from the open trough flotation cells at a coal preparation plant (CPP) in NSW was a solids recovery of 82 wt% at a product moisture of 24.3wt%. By comparison the best product achieved with a conventional wedge wire basket was a similar moisture content but solids recovery was only 64 wt%. This could only be achieved after the feed had been artificially thickened. Conditioning of the centrifuge feed with polymer flocculants led to an increase in recovery up to 88 wt% with a moisture content of ca 25 wt%. It is thought that optimizing additive selection and conditioning parameters, as well as screen aperture and open area, could improve performance still further. The results were obtained using centrifuging conditions (centrifugal force, feed solids, feed rate) in the pilot-scale machine which should be possible to translate into conventional designs of commercial scale machines, without downgrading solids throughputs. However only with full-scale trials will it be possible to establish this assertion with certainty.

Jan 1, 2001

By I. C. Edwards, G. E. Agar

INTRODUCTION Many research efforts over the past years have been devoted to the study of energy consumption in comminution and the characteristics of the broken material. The old "laws" have been superseded by more general methods of analysis1,2,3 but these methods have not received much attention outside the laboratory. The work to be described here was done in order to obtain scale-up information on wet rod milling of sylvinite. EXPERIMENTAL A 30 x 51 in. Denver rod mill with a scoop feeder was used for these tests. Ore was fed from a variable speed screw conveyor into the feed box along with saturated brine. The mill was filled to approximately 45% of its volume with 2400 lbs of a mixed rod charge. The minimum possible feed rate was 2.5 tph and the practical maximum for this mill was 8 tph. Individual tests were run by setting the solid feed rate, then adjusting the brine flow rate to give the desired pulp density. After steady state, as evidenced by constant discharge pulp density, had been reached, samples of the discharge were taken at 15-minute intervals. These samples were filtered, washed with alcohol, dried, then screened on Tyler screens using a Ro-tap shaker. The sylvinite feed was regular plant feed that had been scalped at 20 mesh and was tapped from the coarse ore bins. It had been previously passed through a roll crusher set at 3 inches and after scalping was essentially minus 1 in. plus 20 mesh. RESULTS The screen analysis of samples from each series of tests was plotted on double logarithmic scale paper to determine the reliability of the series. In some cases, a faulty sample or screening procedure dictated that the results of one test be discarded. The criterion is a simple one — if the slope of one plot was noticeably different from the others in the series, it was discarded. The only cases that caused difficulty were those in which the brine was not thoroughly displaced from the solids. When this occurred agglomerates were easily identified on the screens and the whole of the sample was retained on 3 or 4 screens. There were no border line cases. The number N given in Table 1 is the number of size analyses that were pooled to form the data shown in Fig. 1. While examining the reliability of the sizing and sampling by plotting the data, it became apparent that there was no significant difference between grinds made at 50 and 60% solids. For the analysis given here, these tests were regarded

Jan 1, 1967

By J. Olsson

Introduction Stainless steel has by tradition been a common construction material for hydrometallurgy processes and the most common grades can be found amongst the ASTM 300-series, i.e. austenitic grades of type 304L, 316L and 317L. However, there are a number of new grades available today, which imply more cost effective solutions for those designing plants where good resistance to acids, containing the desired metal ions, often contaminated with chlorides and other halides, is the key issue. There are austenitic-ferritic or duplex grades having the same or even better corrosion resistance than the austenitic grades and approximately twice the strength, which enables design in thinner gauges, which in turn implies less weight and less cost. They have also excellent engineering properties, enabling fabrication of process equipment, machinery and different types of tanks. On top of that, they contain less nickel and molybdenum than their austenitic counterparts, which implies not only lower cost for alloying elements, but also a more stable price when considering the price fluctuations for these alloying elements during the last years. This paper describes briefly the family of duplex stainless steel and it presents a number of relevant corrosion tests where duplex grades have been compared with austenitic grades. The results have in several cases been verified by in-plant exposures in zinc and copper production plants. It also describes applications and experience of duplex grades within a variety of hydrometallurgy plants. Installations of highly alloyed austenitic grades will be described as well. The corrosion tests and service experience reported cover hydrometallurgical processes based on sulphuric acid.

Jan 1, 2007

Experiments in the bolting of a mine roof were commenced at Elrington Colliery on the South Maitland Coal Field early in 1949, following the appearance of an article in the American publication, "Coal Mine Modernisation Year Book" 1948. Prior to this, although bolting had not been used in the maintenance of satisfactory roof conditions, the principle of roof bolt anchorage had been illustrated in instances such as the hanging of a trolley locomotive power wire using an expanding shell type of bolt anchorage, or the insertion of an eye bolt with a split and wedge, as used to suspend a rope block over a winze being sunk in a metalliferous mine.The experiments at Elrington Colliery were the first efforts in this country to supplement the work of timber supports under a mine roof with systematic placement of roof bolts.Following the series of experiments at Elrington, full scale bolting was commenced at that Colliery in a trackless mobile section in April, 1950.The obvious success of the system at Elrington indicated that it might also be a success in the support of weak roof strata immediately overlying the workable section of the Victoria Tunnel Seam at John Darling Colliery.The system was commenced at John Darling Colliery in April, 1951, in one mechanical section on the Victoria Tunnel Seam, and the scope was gradually widened until by December, 1952, ail'six mechanical units then operating on this seam were working under bolted roofs.

Jan 1, 1954

By S. W. Stogran

"A brief summary of the environmental testing and analyses required to ensure and maintain compliance of mining properties will be discussed. Programs for new and existing properties and for properties which may be purchased will be outlined and potential solutions to problems will be discussed. In addition to the compliance aspects of operations, due diligence will be discussed.1.0 INTRODUCTIONThe impact of mining projects on the environment is an area of major concern to the public, governmental agencies and mining companies. Due to the ever increasing pressure on the government by special interest groups and the public, governments have implemented legislation to control potential environmental impact of mining, from the exploration phase through to close-out. By not planning for environmental issues during all phases of a mining operation, unavoidable delays and retrofitted environmental programmes will be expensive and cause projects to be delayed, which, ultimately, may cause the abandonment of a mining prospect. Most jurisdictions require at least one full year of background environmental data. Therefore, many thousands of dollars are wasted as construction is interfered with or held up due to data collection. This may be avoided by a thousand dollars worth of sample being collected and analyzed early in the project."

Jan 1, 1992

By F. M. C. C. Vieira

Four mining alternatives for exploiting an ultra-deep orebody were assessed through a multidisciplinary evaluation process which involved: the generation of a 3D geological model; the design and scheduling of life-of-mine layouts; the analysis of anticipated ventilation and cooling conditions; the study of rock-related risks of mining in ultra-deep stress environments; the logistic implications of transporting men, rock and materials; and, lastly, the economic implications of each option. Once results from the integrated mine design assessment were available, mine planners were faced with an important problem to solve: how to identify the optimal mine design alternative when numerous assessment measures and multiple decision criteria needed to be considered simultaneously? To address this ‘multiple-attribute decision problem’ and arrive at the ‘optimal layout for ultra-depth’, a generic decision methodology that uses principles of ‘utility’ was applied. The methodology assumes that ‘single-value risk estimators’ do not account for the inherent variability of real conditions. Therefore, risk estimators were represented by statistical distributions of their incremental changes, where applicable. The stochastic variables, once defined, are used as inputs in the ‘utility’-based layout decision scheme. This ‘utility’-based decision methodology offers a framework for mine design decisions to be made objectively, when complex trade-offs between multiple risk domains need to be considered simultaneously. Upon applying it, one of the layouts emerged as the preferred alternative. Keywords: Utility; mine design; multiple-attribute decision; layout selection

Jan 1, 2003

By J. Nakayama

For drilling large diameter holes for deep foundations, the common and distressing difficulty of long standing has been in coping with ground containing rocky formations and boulders. Where geological formation contains weathered rock or boulders, or deep rock socket is specified, drilling equipment occasionally is found to be unable to drill through and therefore will need supplementary equipment and procedures. Incentive of the MACH Drill Development has been to realize a capable drilling system for rocks of weathered to fresh rock without losing its applicability to usual overburden. Through seven decades' experience of manufacturing and operation of boring machines, the best features of all sorts of drillhead are known such as the drag bit, wing bit, auger bit, diamond bit, rock roller bit, down-the-hole hammer bit, etc.

Jan 1, 1988

By W. L. Zhong

Probability function integration method is one of the influence function method. It is a widely accepted method in many mining districts in China and Poland mainly because its theory and formulae can well-represent the surface subsidence basins due to longwall mining of flat or near-flat seams. This paper introduces the basic theory of the probability function integration method and determines its 4 basic parameters by analyzing the measured subsidence profiles in eight longwall panels in Northern Appalachian Coal field. It also discusses the two methods for determining the 4 parameters. Finally the acquired parameters are used to predict the subsidence and deformation of the houses for damage assessment. Comparisons are made between the measured and the predicted subsidence. Probability Function Integration Method The probability function integration method for predicting surface movements and deformations is widely used in China and Poland. The governing equation of the method contains five parameters: subsidence factor, a, offset of inflection point, d, tangent of the major influence angle, tan fl, horizontal movement constant, b, and major dispersion angle e (e = 90. for flat seams). Its applicable range iis much larger including seams less than 30' from the horizontal, critical and noncritical mining and soft to hard overburden.

Jan 1, 1986