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By Raymond W. Hiteshue

Experiments were conducted al temperatures of 480° to 800° C. and hydrogen pressure of 6,000 p.s.i.g. to determine the effect of coal residence time on the conversion of a high-volatile bituminous C coal to liquid and gaseous products when using a semicontinuous apparatus designed fur rapid heating and cooling of reactants. The objective of the studies at high temperatures was to determine if appreciable quantities of coal could be converted to gaseous hydrocarbons and low-boiling liquid hydrocarbons. Experiments at lower temperatures were designed to indicate shifts in product distribution with respect to temperature and to learn more about the general mechanism of the reaction when using close control of coal residence time. One percent molybdenum, based on m.a.f. (moisture-and ash-free) coal, was used throughout this investigation. At 800° C., 6,000 p.s.i.g., and "zero" residence time) the yield of gaseous hydrocarbons was about 38 percent and the yield of oil about 4.5 percent, based on m.a.f. coal. With IS minutes residence time, under the same conditions, the yield of gaseous hydrocarbons was approximately 80 percent with no increase in yield of oil. Apparently at 800° C., and hydrogen pressure of 6,000 p.s.i.g. coal was rapidly carbonized to char with expulsion of volatiles. Char was then slowly hydrogenated to gaseous hydrocarbons without production of oil.

Jan 1, 1962

By Jones S. C

A specific arc can be cut in hard rock formations using a specially designed multistep piloI bit, variable sized drift joint and long heavy control rod as a stabilizer rather than the Vaughan Thompson "Lifting" arc cuttingequipment. The rate of deflection can be controlled after an initial determination of behaviour in any particular rock type.

Jan 1, 1966

By F. Schlosser

The extension of Montparnasse Station in Paris required the construction of supports of very high unit capacity to support a particularly rigid super-structure. The majority of the site is characterized by the existence of old limestone quarries at a depth of approximately 20 metres. These workings have been backfilled in some places, have collapsed in some places and have given rise to local subsidences in the marne layers above them. This paper addresses the steps taken by the group of companies and their consultants to evaluate the equivalent stiffnesses of the supports necessary for the design of the superstructure, and gives details of the construction techniques chosen by the foundations specialist to adapt to the particular conditions encountered on this site.

Jan 1, 1989

By Hideki Shimando

Periodic weighting and windblast which are caused by the dynamic effects of overburden in a longwall panel significantly affect longwall mining This study describes past experience with wind blast at Miike Colliery, proposes a new loosening system using hydraulic fracturing and moistening, and also discusses strength deterioration in hard-to-collapse roof rocks due to water in order to solve the problems caused by the effects of dynamic roof rocks behavior in a longwall face

Jan 1, 1998

By Gregory T. Ziegler

A complex soil profile and high water table, together with a below-grade active subway tunnel, an above-ground elevated railway line, and the heavily travelled Northern Boulevard all passing above the tunnel alignment, combined to make mining of New York?s Northern Boulevard Crossing what is widely considered to be the most challenging portion of the multi-billion-dollar East Side Access project. The Northern Boulevard Crossing is a vital link in this project which, when completed, will connect the Long Island Railroad to Grand Central Terminal in Manhattan. How the sequential excavation method (SEM) tunneling was successfully accomplished, despite the obstacles, was a textbook exercise in practical innovation coupled with close cooperation between the owner, the construction manager, Hatch Mott MacDonald, the designer, Parsons Brinckerhoff, the contractor, Schiavone-Kiewit, and spe-cialty geotechnical contractor, Moretrench.

Sep 1, 2013

By A. V. Roschin, N. V. Malkov, V. N. Karnoukhov, V. E. Roschin

Reduction interactions in solid phases are widespread and occur in most complex metallurgical processes. Among these processes, reactions between oxides and carbon have a special importance. The authors conducted experiments for comparison of reduction by different reducing agents of impregnated chromite ores, in which grains of the reducible chromite spinel are isolated from direct contact with the reducing agent by layers of non-ore material. The results of the experiments have revealed that the beginning of reduction is preceded by thermal and impurity order-disorder transformation of the oxide lattice whilst the transformation of the oxide lattice into the metal lattice takes place as a result of removal of oxygen anions from the zone of metal germ nucleation. Since anions are charge carriers, increase of their mobility can be monitored by changes in electrical conductivity of oxides. Respective measurements of electrical resistance of ores of different metals and a number of pure refractory oxides under heating have indicated that the beginning of reduction coincides with the time of drastic (tens of thousands times) increase of conductivity of the oxides. Besides, the temperature of the beginning of carbon-thermal reduction is in line with the Tammann temperature, i.e. the temperature of transition from the predominantly surface diffusion to volume diffusion. Segregation of metals from the oxide lattice occurs as a result of merging of anion vacancies with defect electrons on defects of the oxide lattice. The transformation of the oxide lattice into the metal lattice requires a certain concentration of anion vacancies and inflow of electrons from the reducing agent to the site of metal segregation. Such inflow has no difficulties due to the mixed anion-electron nature of high-temperature conductivity of oxides. Thus, the reduction is not determined by oxygen diffusion, it is determined by oxygen vacancies diffusion whose speed exceeds the speed of oxygen diffusion by orders of magnitude. This determines that the kinetics of reduction considerably exceeds the kinetics of oxidation at similar temperatures since oxidation proceeds by means of mass transfer of oxygen through the layer of the generated oxide.

Jan 1, 2004

By Ronel du Plessis, John C. Davidtz, Jan D. Miller

Recent results from electrochemical measurements demonstrate that trithiocarbonate (TTC) collectors are more readily oxidized to their corresponding dithiolates than the dithiocarbonate/xanthate (DTC) collectors. Based on the traditional analysis of collector adsorption, trithiocarbonates might then be expected to be effective for bulk sulfide mineral flotation. Previous bench-scale flotation research had shown that TTC collectors are very effective for the flotation of copper sulfide minerals and PGM (platinum group metal) sulfide minerals. More recently, the TTC collectors were evaluated for auriferous pyrite recovery in benchscale plant scale flotation testing in the United States and in plant tests at Anglogold in South Africa. TTC collectors were also applied in bench-scale testing of a PGM ore. In each case an improved separation efficiency was realized. Fundamental studies at the University of Utah examining the effect of collector structure (functional group, -O-CS2 versus .S-CS2), specifically with respect to auriferous pyrite flotation, are in progress. The effect of collector structure was evaluated with air as well as nitrogen as the flotation gas medium. Experimental techniques utilized included electrochemically controlled contact angle measurements to evaluate mineral hydrophobicity and infrared spectroscopy to explain collector adsorption phenomena at the mineral surface.

Jan 1, 2003

Economic Sustainable Power for Mineral Processing

Sep 13, 2010

By J. O. Lewis, Carl H. Beal

The material for this paper was collected for the most part by C. H. Beal during the years 1916, 1917, and 1918. Many of the conclusions reached in regard to the life of oil wells have already been published by the Bureau of Mines 1 but those presented in this paper deal particularly with the theoretical aspects of oil production. The report discusses some of the fundamental factors governing oil production, taking up first the conditions affecting the. amount of oil in the oil sand, then those factors that control the rate of production of oil wells, and then discusses several related problems, most of which deal particularly with the effect of the production of one well on that of another.

Jan 1, 1921

By P. P. Sinha, D. N. Bhatia, B. R. Ghosh, R. K. Gupta

Medium carbon, low alloy, high-strength steels containing Ni, Cr, and Mo are used for the fabrication of various types of high-strength fasteners required for launch vehicle structures. Cold heading properties and response to hardening and tempering are the essential requirements of the material for fabrication and application, respectively. Combining these two requirements is essentially warranted in high-strength fastener-grade steels. Cold heading properties require ductility, which can be achieved through spheroidizing treatments. In the absence of a suitable spheroidizing cycle for medium carbon 3.8 Ni, 1.8 Cr, 0.3 Mo steel, experiments were carried out with a theoretical understanding of the alloy system. This paper presents the experiments and results obtained after a spheroidizing treatment, which was carried out to optimize the process. Hardness measurements were carried out and microstructural studies were conducted to assess the spheroidization process and to determine the optimal spheroidization parameters.

Jan 1, 2007

By S. Hoskins, S. Chiovelli

"The annual budget for the repair and maintenance of equipment at Syncrude Canada Ltd. is in excess of $450 million. Of this amount, a significant portion can be attributed to the loss of material on various pieces of equipment throughout the operation. In order to effectively battle the different wear and corrosion mechanisms that lead to material loss, it is important to understand how materials behave in the environments in which they are used. Through the work carried out at Syncrude, and work conducted with various external collaborators, significant improvements in both equipment reliability and productivity have been achieved. This paper will review some recent field trials where materials research has demonstrated the potential for significant improvements in equipment run life and reduced maintenance costs. These field trials will demonstrate the need for understanding the interaction between various damage mechanisms and the materials used in different services. The paper will also discuss current areas of focus along with future directions for further work. IntroductionSyncrude Canada Ltd, located in northern Alberta, Canada, operates a mining, extraction, and upgrading facility that removes bitumen from oil sand to produce synthetic crude oil. Oil sand is mined from the orebody using conventional open pit mining techniques. Recently, the mining scheme has changed from a dragline/bucketwheel/conveyor system to a shovel/truck/crusher/hydrotransport operation as depicted in Figure 1. Since the start of production in 1978, the identification, development and application of wear protection has been an ongoing challenge due to the abrasive nature of the oil sands and the massive volumes of materials that are moved. The use of various materials and application processes along with component design modifications has resulted in significant improvements in both productivity and reliability (Adamic et al., 1995; Llewellyn, 1996, 1997; Anderson et al., 1998; Chiovelli et al., 1998).In an effort to continuously improve the operation, Syncrude has been quick to adopt new wear technologies. As seen in Figure 2, since the start of operation, a variety of materials have been used to increase wear performance and ultimately equipment reliability and availability. Although Figure 2 does not show a time axis, the bottom axis may also be used to represent a time progression for the predominate use of these materials at Syncrude. Tungsten carbide metal matrix composite (WC-MMC) overlays are currently the materials of choice for most of Syncrude’s critical production applications. Metal matrix composite overlay technology has potential for significant improvements and Syncrude is actively working with powder consumable manufacturers to advance this technology."

Jan 1, 2004

Soon after the Rosebery concentrator commenced operations in 1936, an investigation was begun in an attempt to discover a substitute for cyanide in lead flotation. Cyanide is an excellent depressant for zinc and iron, but it also powerfully depresses the copper, silver and gold bearing minerals present in Rosebery ore, thus allowing them to pass through to the zinc concentrate or final residue where they are of little or no value.The investigation was not entirely successful, but it did indicate that sodium bisulphite or sodium sulphite could be used as a depressant for zinc without depressing the copper, silver and gold bearing minerals. The sulphites were, however, much inferior to cyanide as apyrite depressant.At about this time, I. W. Wark, using the captive bubble technique, had shown that, at the concentrations normally used, sodium aerofloat is not a promoter for pyrite or galena in alkaline solutions (see his book "Principles of Flotation", p. 188). Some preliminary tests on the production of a copper concentrate from Rosebery ore were therefore carried out using sodium sulphite as depressant and sodium aerofloat as promoter.The results of this work were promising but, since Rosebery ore usually carries only about 0·5% copper, there did not seem to be much incentive to carry the work further. With the outbreak of war, however, Australia became desperately short of copper and the relatively small amount in the ore. became of sufficient importance to...

Jan 1, 1952

As metal prices fluctuated over the years, so too have the fortunes of many of those mining in Canada?s Yukon province. With a rich mining history that dates back to the Klondike gold rush of 1896 to 1898 and continues to thrive today, Yukon has experienced several ?boom-and-bust? cycles. However, during the world?s most recent mining ?bust? Yukon has held strong and has re-mained one of the world?s hottest destinations for mineral exploration. In fact, the area even exceeded forecasts in 2009, more than doubling last year. And the near-future looks just as bright.

Jan 1, 2010

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

Sep 13, 2010

By T. Iwanowski

Stress wave measurements and calculations are often used to make a safe determination of the bearing capacity and the integrity of driven piles. Some applications to the restoration of old buildings in the Old Town of Stockholm are referred to and especially analyses of measurements combined with simulations are discussed here.

Jan 1, 1991

By B. J. Moore

This publication contains 14,242 analyses of gas samples from oil and gas wells and natural gas pipelines in 40 States and 24 foreign countries. These gas samples were collected in the period 1917-85 as part of the Bureau of Mines survey for helium occurrences. The gas analyses contained herein were made by several methods over the period covered. Analytical work on samples collected early in the period was done on the Orsat apparatus. The one-cut apparatus and four-cut fractional distillation equipment were added later. A mass spectrometer was acquired in 1949 and used for all gas analyses made after that time. From 1917 to 1978, helium analyses were made on special helium analytical equipment designed and built by the Bureau of Mines Helium Operations Laboratory. In 1978, this apparatus was replaced in the quantitative helium analysis work by a gas chromatograph.

Jan 1, 1987

By J. J. Forbes

This publication is a revision of the first of a series of four Miners' Circulars originally prepared and issued in 19'29 for use in a course of training designed to prepare mine officials to organize men for rescue and recovery operations. These circulars were revised in 1937 and 1938 and again in 1948. This circular (Miners' Circular 33) discusses mine gases and methods for detecting them. The second of this series (Miners' Circular 34) gives instruction in Bureau of Mines methods of sampling and analysis of mine gases; the third (Miners' Circular 35) describes methods and equipment used for protection against mine gases; and the fourth (Miners' Circular 36) explains procedures used in sealing and unsealing mine fires and in recovery operations after mine fires or mine explosions.

Jan 1, 1954

By H. Saroglou

The anisotropic behaviour of Athens Schist has been brought out through the testing of specimens with varying orientation of schistosity with respect to the major principal stress under uniaxial, triaxial and dynamic conditions. A large number of results from tests on intact rock specimens of the Athens Schist were statistically analysed and evaluated.

Jan 1, 2004

By R. V. Higgins

"INTRODUCTION When nations throughout the world are pitted against each other in a war in which petroleum plays a major role, scientist and engineers of the petroleum industry must give serious thought to ways and means for recover¬ing greater percentages of oil from natural reservoirs than in the past. Petroleum and its products are vital to highly mechanized modern warfare, and the victorious nations will be those whose armies, navies, and air forces are supplied with adequate fuel oil, gasoline, and lubricants until the war is won.Efficient recovery of oil from underground reservoirs depends on many interrelated techniques; evaluation of the producing performance of wells upon the basis of their productivity indexes is one such tool. Oil wells usually yield oil at a maximum rate when first ""brought in"". The rate of production begins to decline soon after the first oil is delivered to the tanks, and although part of the decline usually can be attributed to natural reduction of reservoir pressure as oil and as are withdrawn from the reservoir, a larger proportion frequently is caused by greater saturation of water and as in the producing formation about wells and clogging of the pores of the sands by silt, organic salt, and insoluble hydrocarbons. If the maximum quantity of oil is to be recovered from reservoir sands and rocks by wells, it is then imperative that the ability of wells to produce oil be watched closely and all adverse influences that affect the case with which oil can flow to wells be corrected if possible."

Sep 1, 1942

By N A. Sikwa, L M. van Niekerk, G N. Ndlovu

In June 2012, Lucara Diamond Corporation officially commissioned its Karowe Diamond Mine in Letlhakane, Botswana. The processing plant circuit incorporates variable speed autogeneous milling, a first for African diamond processing - only previously practiced in Russia. The paper discusses the basis for the selection of milling against the more traditional circuits incorporating crushing and scrubbing. It covers early commissioning challenges of operating a mill in an æalien environmentÆ with no immediate reference plant to look up to for bench-marking.The paper describes how these challenges were overcome and learnings quickly incorporated into the mill operating philosophy for maximum diamond liberation and minimum product damage. The plant was commissioned in three months and by August 2012 the production ramp up had reached name-plate capacity. The feed to the mill has varied from highly weathered material to extremely hard kimberlite and the operating philosophy had to be optimised for the full range of ore types. While more work is required to stretch the mill operating envelope coupled with other circuit additions to improve liberation of fine diamonds at minimum capital expenditure, the mill has, to date, performed to its billing.CITATION:van Niekerk, L M, Ndlovu, G N and Sikwa, N A, 2013. Commissioning and operating an autogeneous mill at Karowe Diamond Mine, in Proceedings MetPlant 2013 , pp 215-228 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 15, 2013