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By Anselmo Monteiro Ilkiu

No presente trabalho será apresentado um modelo matemático para a análise da instabilidade plástica de um cilindro de parede fina sujeita a pressão interna, considerando o material com anisotropia normal R no estado plano de tensões. As equações foram obtidas, com base nas teorias elásticas e plásticas, considerando o critério de escoamento de von Mises no estado plano de tensões em termos da anisotropia normal, e de acordo com os trabalhos realizados por Johnson & Mellor [1], Chakrabarty [2] e Al-Qureshi [3].

Aug 16, 2017

Pressure drops were measured in a column packed with glass spheres and wax particles, both in random and preferential distributions. Variables investigated included wax content, gas flow rates, and temperatures.It is shown that for random distribution of wax, pressure drop is exponentially related to wax content above the melting point of wax and that below this it increases with increasing gas rate and temperature.For preferred distribution of wax the highest increase in pressure drop is obtained with horizontal distribution of wax and the least with vertical distribution.Comparison with operating blast furnace data and application of results to practice are also included.

Jan 1, 1970

By Edward G. Cunney

[Track in underground bituminous coal mines was investigated and technology has taken from other industries in order to Main information on conditions that impair the safety and efficiency of the track and to develop guidelines ad useful information on the constriction, inspec¬tion and maintenance of mine track. Volume l contains information oil the investigations, observed track conditions, useful technology from railroads and other industries, derivations of track condition descriptors and limits, conclusions, and recommendations. Volume 2, Guidelines, contains recommended standards and practices for mine track. It includes the relation of track conditions to safe speeds; descriptions and limits for measurable track features such as gage, descriptions of conditions for track components that are normally not measurable, such as subbase soils; construction requirements and techniques; inspection requirements and methods; and methods for managing and performing track maintenance work. As a research product, it 0005 nut repeat the summary or derivations. Volume 5, Inspection Handbook, summarizes recommended standards and procedures from Volume 2 and provides related information for read: refer¬ence by inspectors in tin mines. As a research product to be used in mines, it does not repeat the summary, derivations or references.]

Jan 1, 1977

The income of the Institute is derived from dues, subscriptions to MINING AND METALLURGY and sale of publications. These sources are fortunately supplemented by the interest from invested funds now amounting to over $500,000, a considerable portion constituting endowments for especial purposes. Aside from the medal funds the principal endowments are the James Douglas Fund for support of the Library, the Rocky Mountain Fund and the Seeley W. Mudd Memorial Fund. The income from the two last named is available for the support of research and a variety of other purposes. It is allocated by the Board of Directors upon recommendation of standing committees in each case. An active effort is being made to increase the endowments of the Institute, it being felt that unusual opportunities exist for research and public and professional service through the organization.

Jan 1, 1936

By James F. O?Neil

Brown iron ore deposits in Quitman County, Ga., were investigated by the Federal Bureau of Mines in cooperation with the State of Georgia, Department of Commerce, and the University of Alabama. Ninety-one holes were drilled, having an aggregate footage of 2,188 feet; seventy-one holes penetrated 248 feet of iron mineralization. Average thickness of the ore zone was 3.5 feet under an average thickness of 14.7 feet of overburden. The drilling developed inferred reserves containing nearly 30 million long tons of crude ore with an average analysis of 28 percent iron plus minor quantities of manganese. Test work done by the Bureau on the crude ore samples indicated that they would upgrade by current lug washer practice, with the use of a 1i8-inch screen, and yield 4.4 million dry long tons of concentrate with an average analysis of 52.1 percent iron plus manganese. The weight recovery obtained was 14.7 percent. Research studies made by the Bureau showed that the weight recovery would be increased by changing the screen size without any appreciable sacrifice of grade. The average weight recovery was increased to 18 percent with a 10-mesh screen and 22.8 percent with a 20-mesh screen. Screen tests studies indicated that there was no appreciable interlocking of the iron and manganese minerals and the clay and silica waste particles of the materials retained on a 200-mesh screen. Clay was prominent in micron-size slimes. Silica was deleterious in the minus 20-mesh size.

Jan 1, 1965

By Michael G. Zabetakis

Limits of flammability of normal propyl nitrate (NPN) vapor were investigated at ambient and elevated temperatures. Minimum spontaneous ignition and decomposition temperatures were determined with laboratory apparatus over the pressure range from 0 to 4,000 p.s.i.g. Flame speeds and the detonation susceptibility of NPN vapor were measured at elevated temperatures. Stable detonation was obtained with liquid NPN at elevated temperatures, and the detonation velocity was determined to be between 4,700 and 5,100 m./sec.

Jan 1, 1962

By V. Dinesen

"Grinding is simply the function of reducing particles in size or creating new surface areas. This may be accomplished by many means but we will only concern ourselves with the continuous grinding process as performed in a revolving drum or mill, containing a grinding media. Such a mill consists essentially of a feed head, a cylindrical shell section and a discharge head. To prevent internal wear of these parts it is customary to attach replaceable linings over the wear areas. The specification and design of these mill liners is more important than generally conceded. As they reduce the effective internal volume of the mill, they will consequently affect the whole mill ·design and operation.A number of mill designs of various sizes are available for combined crushing and grinding of materials within a wide size range. For simplif1cahon purposes we will refer 1n particular to conditions relating to standard mill shapes having a length which is greater than the diameter. Such mills usually rotate at speeds between 60% to 85% of the critical speed and may, depending on the grinding media used, be classified as rod mills, ball mills and pebble mills.LINER MATERIALSA great variety of materials have been and are being used for mill linings. These include wood, ceramics and cements, rubber and plastic compounds, rolled and forged steels, cast steels and cast irons, both plain, alloyed and specially treated.The choice of a liner material depends on many factors. In both dry and \\.:et grinding, it may be necessary to consider product purity, colour, chemical reaction etc. but for our purpose we \viii refer to wet grinding operations as generally used within the mining industry."

Jan 1, 1972

By N. R. Dixon

This report summarizes all work performed under U.S. Bureau of Mines Contract No. J0395028, "Noise Control of Rubber-Tired Front-End Loaders Used in Surface Mining. " Two loaders, a Caterpillar 988 and an International H-400B, were chosen for this program, and the noise sources and acoustic paths that contribute to the operator's noise exposure were identified. Retrofit noise control treatments were designed and installed on these loaders, and noise reductions of more than 10 dBA at the operator position were achieved on both machines. The retrofit packages are low cost and have been field tested in two mines for more than two years. The results of the program were communicated to the mining industry through a series of noise control workshops and a field manual. The workshops were given in nine states across the U.S. and more than 440 manuals were distributed An audio/visual slide presentation was also developed which the program.

Jan 1, 1983

By Olga Frank-Kamenetskaya

The experimental results of study of atmospheric corrosion processes on Saint-Petersburg bronze monuments surface, received in situ and by means of simulating experiments, have been discussed. Influence of the time factor on corrosion film (patina) mineral composition has been analyzed. Direct dependence between patina mineral composition and environmental conditions has been proved. The sequence of patina phases crystallization has been established. Effect of the chemical composition and heterogeneity of artistic bronze and also monument surface structure on the rate of corrosion process has been regarded. The time variations of mass of the crystallized in the hydrochloric acid vapor phases have been investigated. The kinetic laws of their development at the initial stage of formation, indicating simple (non chain) reactions, have been revealed.

Jan 1, 2006

By Richard E. Gray

Subsidence due to coal mining is poorly understood by non-specialists. This has led to numerous misconceptions and myths based on limited observations and lack of knowledge. The three most common are: 1. Mine maps are inaccurate. 2. Deep mines are not a problem. 3. If no subsidence has occurred for many years after mining, there is no risk of future subsidence. Maps are important during mining and most are carefully prepared. Future use to evaluate conditions at mine level often includes drilling to confirm what the map shows. Usually, little or no effort is made to tie the surface survey of the property to the mine survey, to conduct a well designed drilling program to confirm the mine map, or to drill test borings vertically. When a mine entry is encountered rather than a coal pillar, or vice versa, and conditions at mine level appear different than anticipated, the first reaction is the mine map is inaccurate. The idea of a safe depth from subsidence is often based on the false premise that mining results in sufficient breakup of the overlying rock strata that bulking compensates for the coal extracted. The safe depth idea first appeared in the literature about 1880 and remained prevalent well into this century. Sadly, it is still encountered. The modern understanding of fragmentation of the immediate mine roof with the overlying beds sagging down on the broken roof rock was first described in 1900. With full extraction mining, either longwall or retreat room and pillar, surface subsidence occurs regardless of the depth of the mine. Subsidence over longwall mines at depths of 2000 feet can be 90 percent of the mined seam thickness. Numerous studies of undermined sites conclude that mining occurred many years ago and since no subsidence has occurred, there is no risk of future movement. This is true if sufficient coal pillars have been left to support the overlying strata. However, every year subsidence occurs over mines that have been closed for 100 years or more. In a study of subsidence incidents over the Pittsburgh Coal, the senior authors found that 50 percent of the incidents occurred above mines that had been closed for at least 50 years and 10 percent over mines closed for at least 80 years.

Jan 1, 1996

By D Chalmers, C R. Ward, B B. Beamish

Coal workers’ pneumoconiosis (CWP) has re-emerged as a major concern in the Australian coal mining industry. Harmful effects from coal dust inhalation have been well documented, but the underlying causes and mechanisms of CWP are still debatable. Research conducted in the USA has proposed a plausible link between the presence of pyrite in coal and the prevalence of CWP. Reactive pyrite in coal oxidises under ambient mine conditions to produce various iron sulfate minerals such as melanterite, rozenite, roemerite and szomolnokite. Rapid reaction rates are promoted by the form (size and morphology) of the reactive pyrite present, which provides both increased surface area and increased porosity for easy air access to reaction sites. The products formed from reactive pyrite oxidation are often needle-like crystals with thicknesses in the order of 1–2 µm (eg melanterite and rozenite) and prismatic crystals with thicknesses less than 5 µm (eg roemerite) have been recorded. The densities of these minerals are significantly less than quartz, which makes them prone to becoming airborne with the normal coal dust. In fact, the mix of these mineral salts is commonly referred to as ‘fairy dust’ by mine workers due to the way they can become entrained and sparkle in the mine ventilation air, particularly if they occur in the upper part of a seam that is forming a coal roof. Examples are presented of the various products of reactive pyrite oxidation found in three Australian coal samples, which provide evidence of the physical and chemical mechanisms that would support the USA findings, particularly in terms of a source of bioavailable iron leading to increased inflammatory stress response.CITATION:Beamish, B B, Ward, C R and Chalmers, D, 2017. Products of reactive pyrite oxidation in the mine environment – implications for coal workers’ pneumoconiosis, in Proceedings Australian Mine Vent Conference 2017, pp 87–92 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 28, 2017

Validation and Application of Filtration Theory to Plate and Frame Pressure Filtration - From Laboratory to Full Scale

Sep 13, 2010

By B. W. Haynes

This Bureau of Mines report describes the laboratory processing of manganese nodules and the results of tailings characterization obtained during the cooperative program with the Department of Commerce's National Oceanic and Atmospheric Administration (NOAA) and the Bureau. Five technically feasible first-generation nodule processing methods were operated at bench scale to generate sufficient tailings and slags for physical and chemical analyses. A description is given for the laboratory operation of the individual unit operations of each process. The laboratory-generated tailings and slags were tested for physical properties, mineral content, elemental and ion content, and leachability for all five processes. The results of leachate testing using the Environmental Protection Agency extraction procedure (EP) toxicity test, the American Society for Testing and Materials shake extraction test, and the EPA-U.S. Army Corps of Engineers seawater elutriant test showed very low to negligible leaching of metals from the tailings and slags. Results of the EP toxicity test demonstrated that the wastes are nonhazardous as defined in the Resource Conservation and Recovery Act (Public Law 94-580).

Jan 1, 1985

By N. Ogbonna

A mathematical model for bioleaching at the agglomerate scale is developed. The agglomerate is defined as a unit volume of a heap which contains a solid phase (a size distribution of ore particles), a liquid phase (stagnant and flowing leaching solution) and a gas phase (flowing air and air pockets). Leaching at the level of an ore particle is modelled using a diffusion-reaction equation, and oxidation by attached and detached microbes is treated separately. With the aid of the mathematical model, the effect of particle size distribution on the bioleaching of an ore containing a mixture of chalcocite and pyrite, and a culture of iron oxidizers, is investigated.

Jan 1, 2006

By Norma Golumbic

The primary purpose of the Bergius (hydrogenation of coal) and Fischer-Tropsch (hydrogenation of carbon monoxide) processes is the production of synthetic liquid fuels. This objective is of importance in insuring an adequate supply of motor fuels and lubricating oils in the United States. In the urgency of the basic research and process development work on synthetic liquid fuels, the possibilities for the production of synthetic chemicals inherent in these processes have hitherto received little attention in this country. However, the by-products, as well as the primary products, from the Bergius and Fischer-Tropsch processes are rich source materials for organic chemicals. The overhead oil from liquid-phase hydrogenation of coal, for example, contains benzene, toluene, xylene, cyclohexane, methylcyclohexane, aromatic solvents, about 20 percent tar acids (largely phenol, cresols, and xylenols), and 3 percent nitrogen bases. Wax, alcohols, and acids are by--products of the Fischer-Tropsch synthesis. In addition, techniques have been developed which make possible the production of aliphatic hydrocarbons, alcohols, acids, aldehydes, and other oxygenated organic compounds. These chemicals are more valuable on a unit basis than gasoline. Because of continued rapid expansion of the plastic, resin, lacquer, and solvent industries, larger amounts of many of these chemicals will be needed in the near future.

Jan 1, 1949

By Henry P. Chandler

THE year 1950 was one of increased activity in almost all branches of the abrasives industry, with nearly all abrasive materials showing a marked increase in tonnage and value. New records were made In the production of tripoli, ground sand and sandstone, pumice and pumicite, and garnet. Total production of crude artificial abrasives in the United States and Canada increased 17 percent in tonnage and 30 percent in value. Imports of industrial diamonds increased 100 percent in total value and 72 percent by weight, the 1950 importation being the largest since 1944. Imports of corundum increased 76 percent in tonnage and 4 percent in value.

Jan 1, 1953

By S. H. Ash

For several years considerable activity has been devoted to economic and social factors affecting California metal-mining operations as they relate to accidents and their cost. The reason for this intense interest is that accidents cost this industry annually over $1100,000 in industrial insurance premiums for mines insured by insurance carriers only; during 1924-32, inclusive, they amounted to $3,616,9115. There are several reasons for this high cost, the most important of w rich are the consistently .high frequency and severity rates of injuries occurring in the industry. Coordination of effort, appreciation of a mutual problem, and widespread education are essential if accidents and their cost are to be reduced.

Jan 1, 1935

By S. F. Burks

"This paper develops themes explained at two SAIMM platinum conferences. Optimization techniques can be used to significantly increase the value of mining businesses by enabling better long-term planning decisions. Open pit and underground mine design, mine scheduling, cut-off grade and blending, stockpiling, and the linking of these to flexible elements of the metallurgical recovery processes are all evaluated together. Transport or sale of intermediate products and the requirements of the product metal markets can also be considered. Experience shows that net present value (NPV) can be increased significantly, usually even before the expenditure of significant amounts of project capital. Recent studies of NPV have aimed to simultaneously evaluate the impact of the optimized financial solution on the non-financial features of a project or operation.The case study presented comprised a commercially orientated review of the prefeasibility study designs and cost estimates of a platinum group metal (PGM) project in South Africa, followed by value chain optimization and sustainability studies of the project carried out simultaneously to identify potential value uplifts to be gained and guide the owners’ team going forward into the feasibility study phase. Some of the major aspects of the project that were found to have significant potential to add value included enhancement of the business model by the application of activitybased costing and theory of constraints, focus on the highest net value portions of the orebody in the early years of production, enhanced and optimized scheduling of the underground mining operation, application of dynamic grind and percentage mass recovery from ore to flotation concentrate (also known as percentage mass pull) to optimize revenue, application of elevated cut-off grades early in the life of mine, matching of the mining and processing capacity, expansion of the operation subject to capital availability, and installation of downstream processing facilities subject to regional third-party capacities.The investigation of non-financial project features focused on demonstrating that a financially optimized solution could also have a number of other benefits. These are mentioned briefly in the paper, which aims to present the status of the project at an early stage of its development."

Jan 1, 2016

The history of zinc production in Australia is outlined including attempts to make zinc electrolytically at Cockle Creek, N.S.W. in the last century, the use of horizontal retorts at Cockle Creek and Port Pirie, South Australia, production by electrolysis at Risdon, Tasmania and at Port Pirie using zinc oxide fumed from lead blast furnace slag and production by the Imperial Smelting process at Cockle Creek. Developments in the electrolytic process are described including those in roasting, acid manufacture, leaching, purification, electrolysis, melting and casting. The Imperial Smelting process technology is also outlined. In both processes global technology is reviewed, including important Australian contributions.

Jan 1, 1986

By C. S. Simons, D. A. Dahlstrom

"Growing interest in the developing technique of improving the dewatering of filter cakes by the direct application of steam has been apparent during the past year. A number of applications to iron and base-metal concentrates are under study, and intensive work continues on applications to coal cleaning.This paper presents and discusses the data presently available. The effects of material characteristics and operating variables on final cake moisture are examined. Although it is not yet possible to answer all questions regarding the applicability of the technique to specific problems from general data correlations, it is found that the use of these in con-junction with empirical data derived from properly conducted laboratory tests does yield reliable conclusions.Emphasis is placed on the basic economics of the process, and on de-sign criteria for ""steam drying"" filter stations, as applied particularly to metallurgical concentrates. Examples of the use of laboratory tests to solve application problems are given."

Jan 1, 1966