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By K McLeod

{Figure 1} The Placer Dome-Western Areas Joint Venture?s South Deep Twin Shaft Complex, has been planned and dreamt of for nearly 20 years. [ ] The gold reserve at the bottom of these shafts is one of the largest single intact gold deposits remaining in the world today, containing an estimated 57 million ounces. This is about the size of the fictitious reserve created by inventive prospectors for the infamous BREEX scam in Kalimantan about ten years ago and about the size of the reserve Harmony claims as its own in it?s current hostile takeover bid for Gold Fields. So it is certainly of the magnitude that dreams are made of. [ ] {Figure 2} The unique orebody lies in a continuous, highly concentrated, thick deposit, an estimated twelve kilometres along dip and a two kilometre wide strike. Due to the thickness of some sections of the reef, up to 60 metres in places, bulk mining methods will be required for it?s extraction. [ ] {Figure 3} The twin shaft system comprises a main shaft which had an initial design depth of 2765m and a ventilation shaft of 2760m, making them the world?s deepest to be sunk in a single lift. The shafts were

Jan 1, 2005

By A. Redfern, B. G. D. Smart

The ultimate objective of the development work presented in the paper is to devise an appropriate method for relating powered support specification to geological conditions and mining practice, thus enabling the longwall method of coalmining to be successfully implemented throughout the varied coalfields of the world. The paper begins with a review of various methods previously used to determine support rating, each method being analysed with regard to its source, the logic and theory which constitute the method, and subsequent recommendations. An alternative approach is then proposed, the Powered supports being considered to be one of three foundations, sharing load with coal ahead of the faceline which acts as another foundation, and the waste behind the supports which acts as the remaining foundation. The load/deflection characteristics of the coal and waste, which in turn are related to geological conditions and mining practice, are shown to affect the load transfer on to and hence the specification of the powered support. In particular the characteristic of the waste foundation is shown to be affected by the caving mechanism, an alternative form to that mechanism accepted for British conditions being proposed and designated "parting-plane-controlled" caving. A finite element solution for a beam on elastic foundations was used to translate the above concepts into numerical results, these results being compared with data from Indian and Chinese operating conditions. The Indian case study examines the effect of using a conventional chock type of support in a one-web back mode when mining towards a roof break generated ahead of the face, while the Chinese case study compares measured subsidence over a longwall with "blocky" roof conditions with the model results. The comparisons are encouraging, suggesting that the approach used is worthy of further development.

Jan 1, 1986

By G. Portillo

Electrospark Deposition (ESD) is a pulsed-arc micro-welding process characterized by using high current electrical pulses, of a short duration, to deposit an electrode material on a metallic substrate. The short duration of the electrical pulse allows for a low heat input over the substrate and an extremely rapid solidification of the deposited material. As a result, the ESD is capable of a wide variety of microstructures like micro-segregationfree solid solutions, nanostructured grains, metastable structures, and amorphous phases. The present work shows a microstructural analysis of rapidly solidified Al-Ni alloys coatings by the ESD process. Field Emission Scanning Electron Microscopy (FE-SEM) and X-Ray Diffraction (XRD) were performed to present the microstructural evolution as a function of the welding parameters. The phases and non-equilibrium metastable structures present in the alloys, and their distribution, were found to be a sensitive function of the alloy composition; hence its formation is governed primarily by thermodynamic considerations.

Jan 1, 2011

By D. Bienstock

The Fischer-Tropsch synthesis is practicable in a reactor where the exothermic heat of reaction is removed by circulating large quantities of recycle gas through a catalyst bed of high-voids content. At an hourly space velocity of 1100, the feed gas, a mixture of 1.5 parts hydrogen to 1 of carbon monoxide, was converted 90 percent, producing hydrocarbons predominantly in the gasoline range. At these conditions a recycle-to-fresh gas ratio of 40:1 was enough to give excellent temperature control with a pressure drop of 1.5 p.s.i. per foot of bed using a steel catalyst in the form of lathe turnings. Steel parallel plates, although offering lower resistance to gasflow, were less reactive and less durable. INTRODUCTION The Federal Bureau of Mines has been engaged in a research and development program since 1944 on the synthesis of gasoline from coal. Gasification of coal with steam and oxygen to yield a synthesis gas--a mixture of carbon monoxide and hydrogen--is being investigated at Morgantown, W. Va.; and the synthesis of gasoline by catalytically reacting the carbon monoxide and hydrogen over iron by the Fischer-Tropsch reaction is being investigated at Bruceton, Pa.

Jan 1, 1960

By C. W. Lee

"Introduction of diesel engines in underground mines may generate severe health hazards associated with exhaust contaminants. One of the most important parameter in determining the optimal air quantity for hazard reduction is the exhaust dispersion. Through analyzing the exact solution of the diffusion equation and its approximation by finite difference method(FDM) , this paper aims at doing a fundamental research to find an efficient dispersion model suitable to the domestic mines. Diffusion coefficients are likely to be small in the underground airways with high ventilation resistance. This makes concentration profiles similar to the convection-based step functions. It is the case for fixed as well as moving engines. Concentration estimation by exact solution is almost impossible in the case of either a single engine moving at a variable speed or the existence of multiple engines. Application of FDM to the diffusion equation including turbulent dispersion results in the various problems; unstable concentration profiles depending on the engine location, nuctuating concentrations near the engine, and overestimation of the dispersion region of which error grows with waning diffusion coefficient.Convection-based dispersion model is found to fit well for dynamic simulation of exhaust dispersion from multiple diesel engines in the airways showing low diffusion coefficients. Its suitability is more likely in the regions with frequent equipment passage. Published"

Nov 1, 1995

Large scale open pit mining at Ok Tedi and Misima are described in this paper. The paper also presents the socio-political problems encountered in the construction, operation and waste disposal of high technology, high output gold and copper mines in very remote and rugged terrains. Despite these handicaps, mining companies from all over the world have established top class mining facilities including huge open pits, underground mines and mineral processing plants to extract rich mineral deposits of gold, silver and copper.Papua New Guinea is the sixth largest gold and copper producer in the world. New projects likely to come on stream before the end of this century would make it the world's third largest gold producer. The mining industry is the largest organised industry in the country employing over 10 000 persons and investing over US $1000 million on these mega projects per year.

Jan 1, 1992

By D. A. Rice, M. C. Fuerstenau

Flotation data indicate that sulfonate and amine adsorb physically on manganese oxide; oleate also adsorbs physically if the zero point of charge is sufficiently high. Chemisorption of oleate occurs on pyrolusite between pH 8 and 9, and possible mechan- isms of collector adsorption involving metal ion hydrolysis are discussed. The flotation characteristics of most metal oxides1-15 have been examined with standard collectors such as fatty acids and sulfonates. From these studies it would appear as though electrical phenomena are important when shorte r-chained collectors are involved. For example, Iwasaki, Cooke, and Choi9 have shown that dodecyl amine and dodecyl sulfate float iron oxide above and below the zero point of charge, respectively. In another system, D.W. Fuerstenau and Modi10 have shown that dodecyl sulfate, dodecyl

Jan 1, 1969

By Robert L. Lagace, Michael A. Grossman, Alfred G. Emslie

This supplement to the final report is a collection of interim and monthly reports and working memoranda prepared during the course of this program to document the progress, methods and results of the work. The supplement is divided into the self-contained sections briefly described below. I. SELECTED MONTHLY TECHNICAL LETTER REPORTS - This section is a collection of selected monthly technical letter reports that briefly summarizes the chronological development of the analyses and results, including the different concepts, theoretical approaches, and methods of data reduction and analysis explored, and the discoveries, insights and findings made along the way. More detailed treatments of the key developments and results are presented in the interim reports and working memoranda reproduced in subsequent sections of this supplementary report, and in the separately published final report. II. BACKGROUND THEORY FOR MEASUREMENT PROGRAM ON MEDIUM AND HIGH FREQUENCY RADIO TRANSMISSION IN COAL SEAMS - Working Memorandum - This working memorandum gives the initial background theory needed to guide the planned measurements and data analyses of this program to describe the propagation of radio waves-in coal seams for the frequency range of 50 to 5000 kHz. III. MODELLING AND DATA ANALYSIS OF IN-MINE ELECTROMAGNETIC WAVE PROPAGATION - Interim Report - This interim report presents detailed treatments of the data analysis and modelling techniques used, and the associated results obtained from conductor-free area propagation data measured by T. Cory in the first set of six coal mines. The mines were located in three highcoal seams; the Pittsburgh seam in northern West Virginia, the Pocahontas No. 3 seam in Virginia, and the Herrin No. 6 seam in Illinois. IV. ANALYSIS OF MF PROPAGATION DATA FROM MARGARET NO. 11, NANTY GLO, EHRENFELD, AND ADRIAN COAL MINES - Interim Report - This interim report presents detailed treatments of several improved data analysis and Modelling methods applied to, and results obtained from, conductor-free area propagation data measured by T. Cory in the second set of four coal mines. These mines were located in three low-coal seams; the Upper Freeport seam in Pennsylvania and West Virginia and the Lower Freeport and Lower Kittaning seams in Pennsylvania. In addition, this report contains a reprint of two papers presented at a Bureau of Mines sponsored EM Guided Waves in Mine Environments Workshop held in Boulder Colorado. One paper describes the three-layer theoretical model and its application to the conductor-free data from the first six mines, while the second paper describes the theory developed for the coupling of loop antennas to a cable in a mine tunnel in a coal seam, and the model's application to data in the vicinity of cables taken at the Margaret No. 11 mine. V. A METHOD FOR NONINTRUSIVE, IN-SITU MEASUREMENT OF COAL AND ROCK CONDUCTIVITIES IN A COAL MINE TUNNEL - Working Memorandum - This working memorandum briefly describes a possible direct method, and its potential advantages and shortcomings, for performing in-situ measurements of coal and rock conductivities. VI. MODELLING AND DATA ANALYSIS OF IN-MINE ELECTROMAGNETIC WAVE PROPAGATION FROM 50 to 5000 kHz - Interim Report - This interim report presents a summary comparison of theoretical and experimental results for conductor- free areas in eleven coal mines located in seven coal seams. It also summarizes the findings and their implications for intrinsically-safe, portable radio communications between roving miners.

Jan 2, 1980

By J. L. Gregg

A STUDY of copper and silver base alloys was made with the object of finding, if possible, useful alloys subject to dispersion hardening. These studies led to the discovery of several alloys showing considerable dispersion hardening, the most important of which, the alloys of copper with iron, nickel, cobalt and chromium silicides, have since been very ably reported by M. G. Corson.1 This paper is offered as a few notes covering alloys other than those described by Corson and some further data on the silicide alloys.

Jan 1, 1929

By M Miller

Operators of nickel laterite pressure acid leach and gold pressure oxidation technology frequently employ a series of steam condensing heaters to preheat the leach feed slurry. The heaters are an economic pinch point û although the thermal performance of the heaters is critical to overall process viability and operating cost minimisation, they are also a significant capital item and must be sized accordingly. Despite this, discussions of the factors underlying heater design are conspicuously absent from technical literature, and existing operations feature a conflicting range of heater sizes and configurations. This variety would suggest that at least some of the chosen heater designs are oversized. As part of its detailed design stage, the Ravensthorpe Nickel Project (RNP) constructed and tested a pilot plant heater to develop an understanding of the heating process and to ensure that the RNP heaters were appropriately sized. This testwork used RNP slurry at design density and viscosity on a 450 mm diameter, 6500 mm high column. The pilot plant testwork demonstrated the intrinsic efficiency of the direct steam condensation heating process, which was essentially independent of slurry density and viscosity. Presence of non-condensable gases in the steam phase decreased the heat transferred in certain circumstances, but heater performance remained consistent with thermodynamic limitations. Stagewise heat transfer within the column was rapid, and suggested either a very high slurry surface area or excellent heat transfer within the slurry phase. While the testwork did not set out to distinguish between these effects, physical evidence pointed to droplet formation in the inter-tray shower zone, giving a high heat transfer area. For scale-up purposes, the key facts were that the heat transfer rate was not limited by using high viscosity slurries and heaters could be designed using the principles applied to the smaller of those in existing operations. This paper discusses existing slurry heater designs, the current understanding from open literature, the pilot plant testwork, results and analysis, and scale-up to commercial sized equipment.

Jan 1, 2005

By A. J. Neale

Much has been published lately about the application of advanced control strategies in the automatic control of autogenous and semi-autogenous grinding circuits. The application of adaptive control algorithms, self-tuning controllers, state estimation, and expert systems has been well documented. While these approaches can be very effective; experience has shown that quite often simply "fixing the fundamentals" can have a significant positive impact on overall grinding circuit performance. This paper will highlight the results of process optimization and process control work by the authors at a variety of autogenous and semi-autogenous installations. A review of one approach for quantifying the mill load/bearing pressure/power relationship is provided. Accurate monitoring of key mill process variables is a necessary prerequisite for both effective process analysis and process control. This paper discusses some of the concerns related to defining steady state operating conditions and the issues related to signal conditioning. The paper concludes with a discussion of an effective application of algorithmic constraint control which incorporates many of these considerations.

Jan 1, 1994

By E. V. Bratygin, E. G. Dmitrieva

The aim of the research was to study the thermodynamic characteristics of high-temperature processing of ilmenite concentrate deposits "Central" in a neutral and oxidizing atmosphere, as well as its interaction with alkaline additives. The research was conducted using a scanning colonoscopy on thermogravimetrical analyzer NETZSCH STA 449 F3. A sample of the test material weighing 10 mg was placed in a crucible and heated at a rate of 10 °C/min to 1200 °C in argon or air. Studies have been conducted pure ilmenite concentrate and its mixtures with 5 % and 12.5% of sodium carbonate. The results of the analysis of the thermogravimetric curves it was found that the recovery of the concentrate carbon will come from ulvospinel, not pseudobrookite, and the reaction recovery is possible at temperatures above 900°C. While removing produced in the decay ilmenorutile of iron oxides in an inactive form, for example, iron (III) oxide, it is possible to reduce the quantity of the solution of ilmenite formed during the restoration of the melt anosovite. The analysis of data obtained during heating of ilmenite concentrate with sodium carbonate in concentrations of 5 and 12.5% transition pseudobrookite in ulvospinel is missing, it just breaks down into hematite and titanium oxide, which, in turn, react with N?2??3. It should be noted that increasing the concentration of sodium carbonate in the sample contributes to more complete interaction of iron oxides and N?2??3 with formation of ferrites of sodium. This can ensure full recovery of iron oxides in the concentrate, which is part of secondary ilmenite can not be dissolved in the melt formed by the lower oxides of titanium. In addition, the increase in the content of soda in the mixture significantly reduces the temperature of the initial melting point of the slag and facilitates the coagulation of metallic iron.The obtained results were used for laboratory studies of the solid-phase sintering of briquettes from ilmenite concentrate with additives of sodium carbonate and a reducing – coal, as well as for the development of technological mode of solid-phase sintering of the concentrate with the aim of obtaining product recovery with a titanium dioxide content of more than 75 %.

Jan 1, 2018

By R. L. Manegold

This paper outlines the reasons for and the application of suspended magnets above belt conveyors for the purpose of removing tramp iron to protect equipment. The design of a magnet strong enough to extract iron through a distance of 24 in. is described along with the proper method of application in the field. Advantages of the suspended magnet in contrast to the conventional magnetic pulley are also discussed. IN RECENT years there has been a decided trend toward bringing ores and coal out of open-pit and underground mines by long, sloping single-stage belt conveyors. Because the high investment cost of haulage conveyors dictates maximum speed and full loading for economy, conveyor belts are running faster than ever before, with a greater burden on the belts. In addition, larger blocks of ore are being mined and conveyed. Rougher use of large mining equipment generates more tramp iron; mechanical loading rejects nothing. Therefore the extraction of tramp iron and other deleterious materials for the protection of haulage conveyors at transfer points, chutes, and idlers is becoming an increasingly difficult job. In our experience, the best method of protecting long haulage conveyor belts is to extract the tramp iron, at least the large tramp iron, ahead of the main haulage conveyor or series of conveyors. It is most practical to collect the tramp iron at the earliest source possible, usually directly after the primary car unloading dump or after the primary crushers, which are ordinarily not affected by tramp iron, see Fig. 1. The coal or ore from its primary source is fed by chutes or feeders onto a buffer or shock belt conveyor, a short, ruggedly built conveyor system that can be considered somewhat expendable. Its primary function is to bring the ore up to speed for transmission to the haulage conveyor. There is no assured method of protecting this conveyor from tramp iron damage at its feed end. Likewise, there is a possibility, although remote if the magnet applied to this belt is installed correctly, that the tramp iron extraction process will damage the shock belt, which is, however, short and comparatively inexpensive. Magnetic head pulleys with their maximum effective range of about 8 or 10 in. cannot be considered for large installations, even though they are desirable because of the continuous and automatic tramp iron removal feature. Further, the most dangerous form of tramp iron with respect to potential damage to a haulage conveyor is the long rod, roof bolt, or rail segment, which is not extracted satisfactorily because of the limited tangential contact of such an iron shape with the magnet. Magnetic head pulleys are also undesirable because the dribble or fines from the head pulley discharge at the same point as the tramp iron. Screens must be used to separate the fines from the magnetics, resulting in additional expense and loss of head room. Magnetic detectors have been used with success, but they only indicate the presence of iron, and the conveyor belt must be stopped for its manual removal. The stoppage of any conveyor means that all preceding equipment must be stopped or a cascade of material on the idle conveyor will result. Occasionally combinations of detectors and magnetic head pulleys are used. The detector precedes the magnetic head pulley and detects only large pieces of tramp iron, while the magnetic pulley subsequently takes out the smaller ferrous metals. Suspended magnets overcome the disadvantages of magnetic head pulleys, detectors or a combination of both. There are several magnetic extraction problems involved in applying a suspended magnet at this

Jan 1, 1953

Develop a metal substitute which is more plentiful and less expensive than the metals currently being used in high performance, permanent magnets, while maintaining the quality of the magnet. The New Alloy The rare-earth metal used in most high performance magnets is samarium, an expensive metal of limited availability. Cobalt is also used in high performance magnets, but supplies of this metal also are limited because it is not domestically mined and must be imported. The Bureau of Mines embarked on research to find a less costly domestic: metal source for use in industrial magnets. The alloy found most promising consists of mischmetal, a relatively abundant, naturally occurring mixture of rare-earths, which can be used as a replacement for samarium. Additives of copper, magnesium and iron used in combination with mischmetal aid in replacing some of the cobalt needed for the magnets.

Jan 1, 1983

By E. DeGolyer

I. INTRODUCTION VOLCANIC origin. was among the first of the theories advanced to account for the occurrence of the salt domes of the Gulf coastal plain, northern Louisiana., and eastern Texas, and it is still being re-stated in various forms by the most recent contributors to our knowledge of the geology of such deposits. Argument has been largely by analogy and attention has repeatedly been called to the Mexican oil fields, particularly those of the Tampico-Tuxpam region, because of the occurrence of oil in close proximity to volcanic plugs in those fields, an occurrence supposed to have some resemblance to the common occurrence of oil in the salt domes of the United States. The author, having spent several months of the past year in a general study of salt domes and in a detailed study of certain domes in the United States, and having been acquainted for some time with the exploration of similar domes in the Isthmus of Tehuantepec region, Mexico, and with the general geology of the Tampico-Tuxpam region, Mexico, has reviewed the various theories of volcanic origin for salt domes which have been advanced to the present time. The purpose of this paper is to present such review and to discuss the supposed Mexican analogy.

Jan 5, 1918

By Kenneth M. Earl

In its investigation of deposits of strategic minerals, the Bureau of Mines lid some development drilling at the Milan deposit in an endeavor to find an additional source of supply of copper. The deposit, which is in Coos County, northern New Hampshire, is about 8 miles northwest of Berlin. It was discovered in the seventies and was worked steadily until 1886, yielding a monthly production of 2,600 tons of ore. Lessees opened the mine again in 1695 and mined 1,500 tons. The Milan Mining & Milling Co. acquired the property in 1907 and made regular shipments of ore and concentrates until 1910. From 1911 until 1938, the tract was held by a local resident for timber land, Ventures, Limited, a mining concern with headquarters at 25 King Street, West, Toronto, Canada, acquired the property in 1938. No production has been recorded since 1910. To cut the vein below the old mine workings and to search for extensions to the northeast and southwest, the Bureau of Mines diamond-drilled eight holes for an aggregate of 3,596.2 feet.

Jan 1, 1950

By W. B. Mather

The object of this paper is to record and interpret data collected during the examination of over 250 barite deposits in the Central Mineral District of Missouri. In the course of this study, the origin of the deposits, which the author believes to be hydrothermal, has been given particular attention. Economic barite deposits occur in two main areas in Missouri: (I) in the Washington County District of Southeast Missouri, from which over 90 pct of the state's production is derived; and (2) in the Central Mineral District, which includes portions of 15 counties in Central Missouri (Fig I). Barite in the smaller Washington County District is mined from widespread low grade, relatively shallow residual deposits, whereas in the Central District, it is mined

Jan 1, 1948

The inauguration of a geological department for the mines of North Broken Hill Limited necessitated the provision of accurate plans and sections upon which geological facts and projections might be plotted.Unfortunately, the basic data were very inadequate. For the British Section, sill survey plans were available, but no regular stope plans. Filling surveys had been preserved for many stopes, but on innumerable pieces of tracing linen, without heights of any kind, and not altogether reliable (as indicated by the finding of very inconsistent duplicates). For the bulk of the old stopes no plans exist at all. The expenditure of much time and patience has resulted in the co-ordination of most of the existing stope data, but the British Section must for the rest of its life continue to have surprises in store, as has been the case for many years past. Manufacture and preservation of stope records has, of course, been on a sound footing during recent years. No reliable cross-sections of the British Section were available.The Marsh, Junction, and Junction North Sections have for the most part very poor data. In the North Section, level plans were fairly reliable, and cross sections of the lode made for ore reserve purposes have been preserved for quite a few years. No floor plans of stopes were kept, however, until a couple of years ago.Diamond Drill records vary in quality. Practically none exist for the Junction and Junction North Sections. Logs have been kept for the British Section drill holes, but are...

Jan 1, 1940

Die Suid-Afrikaanse Instituut vir Mynbou en Metallurgie het 'n paar jaar gelede 'n toekenning vir voortreflike akademiese prestasie deur vierdejaarstudente aan technikons ingestel. Disinvestment campaign by COLIN M.SPENCE As President of the Federation of Societies of Professional Engineers, which is an organization representing twelve institutions of the engineering profession comprising over 18 000 engineers of all kinds-of whom over 15 000 are either professional engineers or engineering graduates-I have been asked to make a statement on the disinvestment campaign on behalf of the profession.

Jan 1, 1985

By Diane F. Baker, Cathy Aimone-Martin

A series of small-scale explosive experiments were conducted in a perlite mine near Socorro, New Mexico. These experiments were a joint effort between Los Alamos National Laboratory, New Mexico Institute Of Mining and Technology, Southern Methodist University, and Defense Nuclear Agency. The purpose of these tests was to measure the changes in the shock wave and seismic coupling as a function of depth of burial and structural setting. The size of the explosive charges ranged from 1 to 68 kg. Over 1150 measurements of velocity and acceleration were made on thirteen experiments using three component sensors. The sensors were placed to maximize the azimuthal coverage as well as to provide data at a variety of ranges from ~1 to 130 m A few far field measurements were made at ranges of ~2Êkm. While the bulk of the measurements were made on the surface, high g accelerometers were placed in one instrumentation borehole to provide some free-field measurements. Preliminary results indicate that significant differences in the amplitudes of signals can occur when the location of the explosive charges are changed by only meters. Part of the observed difference is attributed to variations in the rock immediately adjacent to the charge affecting the shock coupling; and part to the effects of the site characteristics.

Jan 1, 1994