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By Indrajit Paul, Atanu Pal, Kapil Modi, Sanjay Chandra, Chandra Sekhar, Srinivas Dwarapudi

"High alumina content in the Indian iron ore fines (2.5% Al2O3) resulted in poor quality pellets at the recently commissioned 6 MTPA pelletizing plant and a study was under taken to establish suitable pellet chemistry through proper fluxing agents. Limestone fluxed pellets were prepared at varying basicity (0 to 0.8) and pyroxenite fluxed pellets at varying MgO contents (0 to 3%) to study their effect on the metallurgical properties. Fired pellets were tested for their strength, RDI, reducibility and swelling. Microstructural studies, optical and SEM-EDS, were carried out to quantify different phases and their chemistry. Acid pellets exhibited poor quality whereas limestone pellets at 0.8 basicity and pyroxenite pellets at 1.5% MgO exhibited optimum metallurgical quality. Formation of widely distributed silicate melt in limestone pellets and high melting point slag & magnesioferrite in pyroxenite pellets found to improve their quality. However during commercial production of MgO bearing pyroxenite pellets, their room temperature and low temperature properties found to be inferior, but exhibited better high temperature properties, viz. softening-melting behavior. Contrary to this, commercially produced limestone pellets, comprising CaO, exhibited better strength and RDI but showed poor high temperature properties. To yield the benefits of both CaO (for good strength and RDI) and MgO (for low swelling and high softening), a dual flux combination was established by using both limestone and pyroxenite/olivine together that resulted in optimum metallurgical properties. Coke rate at the blast furnaces found to be reduced by 1kg for every1% increase of dual flux pellets in the burden.INTRODUCTION Iron ore agglomerate quality plays a vital role in decreasing the reducing agent consumption and increasing the productivity of blast furnace. In most of the integrated steel works, the burden mix for blast furnace is decided as per the availability of the iron ore agglomerates like sinter and pellets. More attention has been given in recent years to the use of fluxed pellets in blast furnace due to their good strength and improved reducibility, swelling and softening melting characteristics. Generally, quality of pellets is influenced by the nature of ore or concentrate, associated gangue, type and amount of fluxes added and their subsequent treatment to produce pellets. These factors in turn result in the variation of physicochemical properties of the coexisting phases and their distribution during pellet induration. Hence properties of the pellets are largely governed by the form and degree of bonding achieved between ore particles and the stability of these bonding phases during reduction of iron oxides (Panigraphy et al., 1990). It is important to note that conditions and parameters of pelletizing are specific to given ore or concentrate; the present study is undertaken for typical Indian hematite ore fines high in alumina. Except authors earlier work on quality of pellets from Indian iron ore (Dwarapudi et al., 2008, 2010), there is no considerable literature reported on the effect of pellet basicity and MgO content in the basicity range of 0 to 0.8 for Indian hematite ore."

Jan 1, 2018

By Lewis C. Karrick, Martin J. Gavin

"Introduction.The theory of fractional ""education"" of oil from oil shale has been used by several inventors as the basis for the design of retorts for the production of oil from the oil shales of the United States. The term fractional ""education"" gives expression to the rather common belief that when an oil shales is heated it produces light, low-boiling oils as low temperatures, and increasingly heavier, higher-boiling oils as the temperature of retort¬ing rises. The theory evidently had its origin in the fact that crude petroleum may be fractionally distilled, yielding light oils at low distillation temperatures, and heavier oils as the distillation temperature increases is as, gasoline is produced from petroleum at relatively low temperatures, kerosene at higher temperature, and heavier products such as gas-oil and lubricating distillation at still higher temperatures.The writers have examined several oil-shale retorts designed to take advantage of the belief that crude, and in some cases refined, gasoline can be recovered from the shale at low temperatures; kerosene at higher temperat.res, and so on. Such retorts are usually designed to operate continuously and have several vapor-pipes lending from them at differing intervals and passing to separate condensers. Designers of such retorts repeat that the distillate from the low-temperature parts of the retort will be gasoline, and that as the shale passes to zones of increasingly higher temperatures, the vapor lines lending from these zones rill remove increasingly heavier products such as kerosene, gas-oil etc."

Mar 1, 1924

By F. Malek

At Creighton Mine, magnitude events are a regular occurrence due to depth and major seismically-active structures. Over the last ten years, major advances have been made in research and development to develop strategies for the management of these major events. Today, the number of rockbursts has been drastically reduced at the mine and damage due to seismic events, when they occur, is often minimal. This paper describes the evolution and implementation of appropriate geomechanics strategies, designs, and practical ground control measures undertaken for the management of seismicity at Vale Inco?s Creighton Mine. A description of the research and development approach, implementation, and ground control strategy is provided for placement of enhanced support systems to manage the consequences of magnitude events at Creighton

May 1, 2009

By David B. Brooks

INTRODUCTION Resources are not; they become (Zimmermann 100) . The companion concepts of reserves and resources appear, one way or another, in almost all considerations of mineral supply. Yet, no other concepts in the economics of the mineral industries have occasioned so much confusion. Whereas everyone agrees that in general the terms refer to the amounts of material that-depending upon technology, market conditions, and institutions-will become available for production in the near or more distant future, the apparent agreement disappears when we come to more specific definitions or to application of the definitions. Some definitions emphasize the physical aspects of reserves and resources, while others emphasize the economic. Some treat reserves and resources as fixed quantities, while others regard them as continually varying. Some consider that reserve and resource estimates have validity only for individual deposits, while others insist that they can be measured with sufficient accuracy for regional or national planning. This confusion in concepts that lies at the very heart of mineral economics is both strange and not so strange. It is common in the social sciences to find concepts that have been adopted into scientific jargon from popular usage and given rather special meanings -at the same time that they continue to be widely used without such qualifications. Psychologists have the same trouble with personality and sociologists, with community. Nevertheless, an attempt must be made to straighten out the various meanings of reserves and resources, or at least to clarify the conditions under which different meanings are applicable, before much progress in analysis of mineral problems can be expected. That is the objective of this chapter. Throughout the chapter, an attempt has been made to provide enough references to guide the interested reader to the most pertinent works on the concepts under study. However, even in a review article, it is no longer feasible to provide a comprehensive set of citations; there are simply too many. In many instances the works cited will themselves include the bibliographies needed to complete a literature search; those that are particularly useful in this respect are so noted. Also, because of the limited availability of foreign periodicals, some important works -originating largely in Canada, France, the

Jan 1, 1976

The history of mining is rightly proud of its achievements in improving productivity and cost improvements over the years. No matter what measure is used, tonnes per manhour, cost per tonne, etc vast improvements have been made over the last hundred years. In fact over the last ten years in Australian coal mines raw coal output per employee has increased by 60 per cent. When one examines why these improvements have taken place the principal reasons have been technological advancement in mining equipment, excavator and dump truck capacity increases, longwall and continuous miners continually improving in reliability and size. Of course all these improvements are correlated to an increase in capital cost. Even with the above-mentioned advances the pressure for increased performance is as strong as ever. The international mining and mineral-processing sector is currently operating in a recessive market with some traditional commodities, eg gold trading at 20 year lows. During recessive times senior management will demand greater returns on capital employed: the obvious choices being reducing costs or increasing throughput. In addition, head office environments will often place a capital freeze on operational management so the opportunity to take advantage of technological change is not available. The challenge is, therefore, to increase throughput and cut costs without the need for capital. The answer is to optimise the existing labour and plant. If done systematically a result in productivity improvement, in our experience, as high as 45 per cent can be achieved with the average across South East Asia and Australasia being 21 - 23 per cent. The intention of this paper is to present a systematic approach to labour and machine utilisation thereby gaining the greatest possible return on the existing capital base.

Jan 1, 1999

By T Roberts, S Talu

Steel wire weld mesh is a common industry standard surface support used in underground mining, traditionally installed with mining drills during the bolting cycle. As underground mining depth and stress increase, mining methods and their sequences at these depths place challenges on conventional surface support options. These challenges have provided a need for high capacity surface support options that improve development efficiency, reduce the need for secondary ground support installation and is easily installed with current mining equipment. A 5m2 mesh testing machine was built, suspending a 9500kg concrete slab, designed with multiple hold down points to test varying bolting patterns. Mesh load and displacement is accurately measured using a data acquisition system which pushes against the restrained mesh module with an available 200kN load and 1200mm displacement capacity. A testing program comparing conventional surface support, straps and combinations of both were tested for baseline results. New module designs incorporating existing mesh types and new design concepts were manufactured to allow for single pass installation during a bolting cycle. Nine mesh types, mesh/strap combinations and new mesh module designs were compared using the same test method. Based on these results, two high capacity mesh module types are produced. This paper will detail the test program, load and displacement results and underground mesh module performance, describing the two high capacity mesh modules function within the development cycle and manual handling. CITATION:Roberts, T, Talu, S and Wang, Y, 2018. Design and testing of high capacity surface support, in Proceedings The Fourth Australasian Ground Control in Mining Conference (AusRock), pp 303–322 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 30, 2018

By R. H. Duval

"In May 1936, Pamour started producing gold by cyanidation of flotation concentrates, and in 1939 was milling about 1, 600 tons per day.Refining records dating from 1939 show two oil-fired furnaces in use, (Rockwell type 46 11 x 29 11 inside oval shell).Refining time averaged 7. 83 hours during the year 1939, indicating a complete refining shift of about 9. 33 hours. That year appears to be characteristic of the period with regard to time required and results obtained.For that year total fineness (gold + silver) of the bars averaged 940 (approx.), but it frequently dropped below this figure, sometimes far below.Furnace lining life varied widely from three to seven or more months. Sillimanite was the standard lining but Mullfrax 41 was frequently used.For many years refining practice remained practically unchanged, and in 1960 procedure still consisted essentially of mixing a flux(% Composition Borax 41, Silica 11, Soda-Ash 11, Nitre 15, Mn02 22) with cyanidation precipitate in the ratio of l. 2 to l and heating to a medium heat (yellowishred, 2000° F) with a low flame for a long time. Time required was about 10. 5 hours per refining. Results were still much as detailed above.At this time it was decided to revise refining procedure, in an effort to shorten refining time and obtain consistently good bullion fineness."

Jan 1, 1965

By Harry W. Campbell

In 1986 at the request of the U.S. Bureau of Land Management, the U.S. Bureau of Mines studied the 2 acre North Sisters Rocks Wilderness Study Area (OR-12-8) in order to evaluate its identified mineral resources. The Wilderness Study Area is located in Curry County, Oregon, about 15 miles north from Gold Beach. No mines, prospects, or mining claims were located inside the study area, and no mineral resources were identified. Stone from the study area could be quarried and used for construction purposes; however, two nearby quarries have sufficient stone to satisfy local construction needs. INTRODUCTION This report describes the USBM (U.S. Bureau of Mines) portion of a cooperative study with the USGS (U.S. Geological Survey) to evaluate mineral resources and mineral resource potential of the North Sisters Rocks WSA (Wilderness Study Area) 1/ at the request of the BLM (U.S. Bureau of Land Management). The USBM examines individual mines, prospects, claims, and mineralized zones, and evaluates identified mineral and energy resources. The USGS evaluates potential for undiscovered resources based on areal geological, geochemical, and geophysical surveys. Results of investigations will be used to help determine the suitability of the North Sisters Rocks WSA for inclusion into the National Wilderness Preservation System. Although the immediate goal of this and other USBM mineral surveys is to provide data for the President, Congress, government agencies, and the public for land-use decisions, the long-term objective is to ensure the Nation has an adequate and dependable supply of minerals at a reasonable cost.

Jan 1, 1987

This paper explains why the valuation of mining assets is often a very different exercise from the valuation of the shares in the mining company which owns those assets. The fundamental reason for this is that mining assets, and the shares of the company which owns those assets have different risks. In order to properly value mining securities it is essential to: ò ensure all the different risks and other factors which impact on the value of the mining assets and the value of the shares are taken into account; and determine the extent to which the different risks and other factors are addressed in the value of the mining assets and the value of the shares so as to avoid double counting or not counting at all. If the alternative, but far from consensus, view is accepted that the correct valuation methodology to apply to shares in mining companies should be based on option pricing theory then conventional valuation practice of both mining assets and shares in mining companies will need to be fundamentally reassessed.

Jan 1, 1994

By Warren B. Weeks

The year 1940 saw an increase of 20 per cent in oil production over the previous year—compared with a 16 per cent increase the previous year. In all, 25,790,380 bbl. were produced, an increase of 4,414,150 bbl, over 1939 and the largest production figure for south Arkansas since 1928. The older settled production continued to decline. Magnolia accounted for most of the increase, with aid from the other recent deep fields. During the year, 169 wells were drilled, 79 fewer than in the previous year. Of 131 wells drilled in proven fields, 18 were dry. Three of the 38 wildcats were pool openers. The drilling depth record was increased from 9028 to 9550 feet. Trend of Prospecting For the first time since 1936, the search for oil in the deep Smackover limestone slackened perceptibly; g dry wildcats ended in Smackover, 2 in. the underlying Eagle Mills; 7 penetrated Paleozoic beds, while 9 ended in Hosston, 2 in Glen Rose, 2 in Paluxy and 4 in Gulf. Geology The wells listed in Table 2 either resulted in the discovery of new oil pools or, because of their depth or location, afforded impor-tant stratigraphic or structural informa-tion. Fig. I is a general columnar and stratigraphic section showing the relation-ship of the strata within the Comanche series. The nomenclature shown was ac-cepted by the Shreveport Geological Society. It was subsequently published by Imlay,l who indicated probable correlations with other areas and presented evidence for the possible Jurassic age of the under-lying Cotton Valley and Smackover formations. New Fields Pouke.—On June 10, 1940, the Louark Producing Co. completed its No. I Sturgis, sec. I, T. 17 S., R. 27 W., in central Miller County, producing between 3583 and 3607 ft. in the upper part of the Paluxy forma-tion. The well flowed I00 bbl. of 3r.4' gravity oil per day through Ns-in. tubing choke. This discovery resulted from seismograph work. Six other wells were drilled in the area, none of which found production in the original sand. One of these wells is producing from a sand 50 ft. deeper in the section. The others were abandoned. No further development is in prospect. Production is from lenticular sands of the upper Paluxy; 45,556 bbl. had been pro-duced by the end of 1940. There is structural closure against a fault to the northwest. McKanzie.—The Atlantic Refining Com-pany's No. I Bodcaw Lumber Co., sec. 29, T. 17 S., R. 23 W., eastern central La-fayette County, was completed June 8, 1940, as the eighth and farthest west of the Smackover (Reynolds o6lite) limestone pools. The well flowed 10 bbl. an hour of 58.6' gravity distillate through an 1 1/64 Ma-in. tubing choke, with a gas-oil ratio of 8400:I.

Jan 1, 1941

By Warren B. Weeks

The year 1940 saw an increase of 20 per cent in oil production over the previous year—compared with a 16 per cent increase the previous year. In all, 25,790,380 bbl. were produced, an increase of 4,414,150 bbl, over 1939 and the largest production figure for south Arkansas since 1928. The older settled production continued to decline. Magnolia accounted for most of the increase, with aid from the other recent deep fields. During the year, 169 wells were drilled, 79 fewer than in the previous year. Of 131 wells drilled in proven fields, 18 were dry. Three of the 38 wildcats were pool openers. The drilling depth record was increased from 9028 to 9550 feet. Trend of Prospecting For the first time since 1936, the search for oil in the deep Smackover limestone slackened perceptibly; g dry wildcats ended in Smackover, 2 in. the underlying Eagle Mills; 7 penetrated Paleozoic beds, while 9 ended in Hosston, 2 in Glen Rose, 2 in Paluxy and 4 in Gulf. Geology The wells listed in Table 2 either resulted in the discovery of new oil pools or, because of their depth or location, afforded impor-tant stratigraphic or structural informa-tion. Fig. I is a general columnar and stratigraphic section showing the relation-ship of the strata within the Comanche series. The nomenclature shown was ac-cepted by the Shreveport Geological Society. It was subsequently published by Imlay,l who indicated probable correlations with other areas and presented evidence for the possible Jurassic age of the under-lying Cotton Valley and Smackover formations. New Fields Pouke.—On June 10, 1940, the Louark Producing Co. completed its No. I Sturgis, sec. I, T. 17 S., R. 27 W., in central Miller County, producing between 3583 and 3607 ft. in the upper part of the Paluxy forma-tion. The well flowed I00 bbl. of 3r.4' gravity oil per day through Ns-in. tubing choke. This discovery resulted from seismograph work. Six other wells were drilled in the area, none of which found production in the original sand. One of these wells is producing from a sand 50 ft. deeper in the section. The others were abandoned. No further development is in prospect. Production is from lenticular sands of the upper Paluxy; 45,556 bbl. had been pro-duced by the end of 1940. There is structural closure against a fault to the northwest. McKanzie.—The Atlantic Refining Com-pany's No. I Bodcaw Lumber Co., sec. 29, T. 17 S., R. 23 W., eastern central La-fayette County, was completed June 8, 1940, as the eighth and farthest west of the Smackover (Reynolds o6lite) limestone pools. The well flowed 10 bbl. an hour of 58.6' gravity distillate through an 1 1/64 Ma-in. tubing choke, with a gas-oil ratio of 8400:I.

Jan 1, 1941

By S Lockie, G Ivanova, J Rolfe

One of the consequences of mining expansion in the Bowen Basin region of Central Queensland in Australia has been a substantial increase in demand for housing, with subsequent impacts on housing and rental markets. Those pressures are reduced to some extent by a proportion of the workforce choosing to live in other centres and commuting to workplace for block periods. The main factors influencing location choice are: housing availability and affordability, basic urban services and lifestyle of the town and the town physical attractiveness such as coastal town. Low costs housing provided by the mining company acts as an attracting factor for some miners to live in the mining town. Recommendations for three short-term and two long-term strategic policy guidelines to address housing situation and location issues are provided.

Jan 1, 2009

By J. E. Burke, C. W. Mason

IN attempting to study precipitation from a tetragonal lattice using solid solutions of bismuth in tin, it was found that although a Widnmanstatten pattern is observed 1 only a qualitative analysis of the orientation relationships is possible, because of the unusual structural changes that accompany the precipitation process MICROSCOPICAL STUDIES Alloys were made from Chempur tin (Standard samples 42b and 42c, National Bureau of Standards), and bismuth (Kahlbaum C P ) by melting neighed quantities together under palm oil, stirring well, and casting in a heated graphite mold The polishing and etching techniques employed largely govern the visibility of the structural changes The preliminary surfacing operations were similar to those recommended by Villela and Bergekoff,5 through BehrManning 3/o abrasive papers, lubricated by a solution of paraffin in kerosene A rough metallographic polish was next given, using a thin cotton cloth charged with relevigated alumina (maximum particle size of about 4µ) and soap solution, repeated etching and polishing served to remove disturbed metal For high-power examination better preparation was necessary It was found that on such soft metals the threads of the fabric, rather than the abrasive, cause most of the scratching Cotton outing flannel, which had been brushed so that the nap lay down, was fairly satisfactory, but a Heavy grade of silk velvet (not the noncrushable kind) was found to be better, especially after some use A better procedure was as follows The metal lap was warmed slightly, and a 4-in circle of woolen broadcloth was cemented to its center by a thin film of melted paraffin The broadcloth was then moistened with water, and a 30 to 40 per cent solution of sodium hydroxide heated to about 50°C was poured over it, allowed to stand for 1 to 2 min and then washed off It was neither necessary nor desirable to remove all the sodium hydroxide from the cloth, since its etching action aided in the removal of the flowed layer from the sample The cloth was then charged with a paste of the relevigated alumina in water Since this lap did not remove deep scratches, it was necessary previously to polish the specimen on some material such as the silk velvet The sodium hydroxide softens and partly gelatinizes the woolen lap covering, permitting a scratch-free polish, but its action continues, and the cloth deteriorates after about 24 hr This is not serious, because a new lap can be prepared in about 5 min, and only small pieces of cloth are used Etching with a strongly acid solution of ferric chloride was found satisfactory for removing the flowed layer For the final etching, the most satisfactory reagent was that of Taffs,7 the formula for which is FeC13 6H20, 2 grams, HC1, 5 c c , H2O, 30 c c , C2H5OH (95 per cent), 60 c c This etchant reveals differences in com-

Jan 1, 1941

By O. Naiker

Xstrata has modified and improved on the solid state reduction of chromite (SRC) process that was pioneered by Showa Denko in Japan and previously used at Xstrata?s Lydenburg plant. The history of pre-reduction is a long one, with the SRC process being the first and only commercially successful one prior to Premus. Krupp developed the chromite direct reduction and the rotary hearth for the pre-reduction of chromite. However, these processes have not been successfully commercialised. The are a number of significant differences between Xstrata?s patented Premus and the original Consolidated Metallurgical Industries (CMI) process. These include, the use of lower cost anthracite fines as the reductant source together with the use of unactivated bentonite as the binding agent. In addition the use of oxygen as an energy source is used in Premus but not in the original CMI process. There was a fundamental change in the operational philosophy of the process in that while the original CMI process aimed to maximize metallization of the pellets, the Premus process seeks to maximize the energy output from the kiln while still achieving the required efficiencies and hence increasing furnace output. Premus is designed to reduce electrical energy consumption, provide high recoveries of metallic oxides, and utilizes low cost reductant and energy sources such as anthracite and oxygen respectively. Due to the fact that Premus is one of the most technologically advanced and competitive processes used today in the production of ferrochrome it was the process selected for Xstrata?s new ferrochrome facility, Project Lion, that is due to be commissioned in the third quarter of 2006 in the Steelpoort Valley in Mpumulanga, South Africa.

Jan 1, 2007

By C. C. Clark, J. R. Mihalisin, K. G. Carroll

OBSERVATIONS made in this paper were for the purpose of exploring the anomalous behavior of a particular heat of Type 310 stainless steel. The alloy, of nominal composition 25 pct Cr, 20 pct Ni, was observed to form a grain boundary precipitate at exceedingly high rates. A sheet of this metal, 0.060 in. thick, after cooling in air from 2000°F showed the presence of the grain boundary material, whereas none was found after water-quenching from the same temperature. X-ray techniques were applied without success and, in view of the ex-

Jan 1, 1958

By C Nucifora, M Landers, J Jones, G Maddocks, K Mandaran, A Forbes, W Wilson, S Newman

Glencore’s Mount Isa Mines Limited (MIM) operates the Mount Isa open cut and underground copper (Cu) and zinc-lead (Zn/Pb) mines near Mount Isa in Queensland, Australia. Tailings from processed Cu and Zn-Pb ore is contained in a 1,315 ha shallow (< 35 m deep) multi-cell valley fill tailings storage facility (TSF). Static geochemical testing conducted by MIM over the life of mine (LoM) verifies that the Cu, and Zn-Pb tailings has a wide range in sulfide content and diverse mineralogy with significant acid neutralising capacity (ANC) in some samples. The tailings are predominantly classified as potentially acid forming (PAF) using static analytical methods. Kinetic leach testing using free draining columns and humidity cell tests simulating tailings placed on the surface of the TSF suggest that the tailings samples are likely to remain non-acid forming (NAF) for 10 to 40 years under aerial exposure, and much longer than this under saturated conditions within the TSF. During this period of weathering, as ANC is depleted, the neutral pH drainage may contain elevated concentrations of some elements including sulfate, manganese and zinc. Only when the ANC is depleted would the tailings then begin to produce acid drainage. CITATION:Mandaran, K, Jones, J, Nucifora, C, Maddocks, G, Landers, M, Forbes, A, Wilson, W and Newman, S, 2018. Mount Isa Mines Rehabilitation Materials Sampling and Analysis program for closure planning, in Proceedings Life-of-Mine 2018, pp 138–140 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 25, 2018

From March to May of 1963, the Bureau of Mineral Resources carried out an experimental aeromagnetic survey at Cobar, New South Wales, to field test a proton-precession magnetometer installation in the Cessna aircraft VH-GEO. The Cobar area was chosen as considerable information was already held on the Earth's magnetic field there, which was known to provide a range of anomalous areas that are not excessively disturbed.A procedure for survey flying and methods for processing data were developed during the survey. Contour maps of the aeromagnetic results were produced in the field. The experimental survey was successful in outlining magnetic anomalies in detail.INTRODUCTIONSince 1951 the Bureau of Mineral Resources, Geology and Geophysics (B.M.R.) has carried out an airborne magnetometer exploration programme with DC.3 aircraft carrying fluxgate magnetometer equipment. Recently a proton-precession magnetometer was developed by the Design and Development Group of the B.M.R. for observatory use. One unit modified for airborne use was installed in the Cessna light aircraft, VH-GEO. The Cessna was modified structurally to take the magnetometer, associated bird, and winch gear.The proton-precession magnetometer has many good features.1. It utilises the transistor and associated solid-state devices in its electronics, and hence is light and small.This is the basic feature allowing its installation in a light aircraft. The transistor circuits have a high reliability factor and owing to the card sub-unit...

Jan 1, 1964

By E. J. Meets, C. F. Meyer

Bord and pillar mining at shallow depth (400 m approx. maximum) is widely used in South African coal mines. One of the problems encountered in extracting coal in this manner is the ventilation of advancing bord and pillar headings. The traditional ventilation methods of force, exhaust and overlap (force/exhaust) are reasonably effective but tend to be both cost and labour intensive. Ducting often restricts the available free area of roadways thus impeding the transport of coal and other materials inbye the coal production section. Due to the above facts, ductless fans are currently being used to minimize the amount of ducting required in advancing sections. Two different types of fans are used, namely, vortex fans and the so-called `jet' fans. Vortex fans were developed from the fan blade design used for vertical take-off aircraft. The fans have the capability of delivering air over distances of about 30 m in the underground situation without any ducting attached to it. Jet fans are standard axial flow fans fitted with outlet reduction pieces which increase the velocity pressure at the discharge to such an extent that the air delivery distance is improved to almost match that of vortex fans. The paper describes some applications of both these fan types in advancing bord and pillar sections.

Jan 1, 1993

By R. G. Charles, E. A. Gulbransen, S. Barnartt

KINETICS of the reaction of zirconium with pure oxygen at elevated temperatures have been studied by several workers for periods of time up to 6 hr.1-1 In two cases,3-4 . the experimental values of oxygen uptake, w, as a function of time, t, were best fitted to the parabolic rate law w2 = kPt + constant. In others,3,4 the cubic rate law w3 = kot + constant, showed better agreement. The most recent data of Gulbransen and Andrew4 indicate that the choice between the parabolic and cubic laws for empirical representation of the data will often be arbitrary. This is particularly true if the first few minutes of the reaction with a clean zirconium surface is attributed to a different oxidation mechanism, for deviations from either rate law were found primarily during the initial period. Thus, the kinetics of this reaction have been too uncertain to permit safe extrapolation to oxidation periods of practical interest (many hundreds of hours). The data to be described are of interest, for they indicate that the cubic rate law applies over long oxidation times. The reaction of zirconium with oxygen at 1 atm pressure was followed at 350" and 450°C for 500 and 200 hr, respectively. Abraded test specimens of pure zirconium sheet' 3.0 X 2.0 X 0.012 cm in size were oxidized by the procedure previously described,3 which included periodic cooling to room temperature for weighing. The surfaces were polished to a 4/0 finish using polishing paper wet with kerosene, then wiped with petroleum ether and washed in redistilled acetone. Fig. 1 shows plots of log ? vs log t. Each curve represents the average of duplicate measurements, and deviations from the average were generally less than 3 pet. The cubic rate law (slope = 1/3) is closely followed. The rate constants, 5.2, x 10 -6 and 2.4, X 10- (mg cm-2)3 per hr at 350" and 450 oC, respectively, are plotted as log k, vs 1/T in Fig. 2, together with cubic constants calculated from the data of Gulbransen and Andrew4 for abraded specimens from the same lot of zirconium. Their data refer to runs of 6-hr duration at a pressure of 0.1 atm 0 and under conditions of uninterrupted heating. In spite of these differences, the latter data yield a straight line which appears to apply equally well to the new extended time data. The energy of activation for the oxidation process, calculated from the slope of this line, i.s 38 keal per mole. This may be compared with the value of 47 keal per mole found by Belle and Mallett3 at higher temperatures. It may be concluded tentatively that extrapolation of short-term oxidation data for zirconium to obtain the long-term behavior is best done through the cubic equation ?3 = kpt + constant. References ' E. A. Gulbransen and K. F. Andrew: AIME Trans., 1949, vol. 185, p. A.515; JouRNal OF Metals, August 1949. 'D.p. Cubicciotti Journal Amer Chemical August1949.Soc., 1950, Vol. 72, P. 3 V. Belle and M. W. Mallett: Joulnal Electro chemical Soc., 1954, ' E. A. Gulbransen 339.and K. F. Andrew: Oxidation of Zirconium Between 400" Gulbransenand 800'C.and AIME Trarzs.. 1957, vol. 209, p. 394; JOUR-Nal of Metals, April 1957. IS Barnartt, B G. Charles, and E. A. Gulbransen: Oxidation of 50 weight pet uranium-zirconium alloy, Journul Electrochemical SOC., 1957, vol. 104, p. 218.

Jan 1, 1959

This publication summarizes the in-house and contract research and development projects programed for fiscal year 1981 by the Bureau of Mines under its Minerals Environmental Technology activity. The document provides a mechanism for interested parties, including potential contractors, to gain insight into ongoing and projected work of the Bureau?s environmental research efforts. Research to identify and correct environmental problems associated with mining and metallurgical operations has long been an integral part of the Bureau's mission. The environmental research and demonstration activities of the Bureau were consolidate in 1979 with the formation of the Minerals Environmental Technology program, which is directed toward the elimination or reduction of environmental problems associated with the extraction and processing of minerals. Among the efforts underway are development of data and technology for assessing the potential environmental impact of minerals development, for monitoring minerals extraction operations, and for establishing viable reclamation requirements on abandoned mine lands; development and demonstration of technology 'or control of environmental disturbances during minerals extraction operations; development and demonstration of land reclamation and mine closure techniques to restore or enhance the productive use of mined lands; development of engineering techniques that incorporate state-of-the-art mining environmental technology in the design and planning of minerals extraction operations; development and demonstration of new mining systems that greatly reduce or eliminate the adverse environmental impacts of minerals extraction; and providing the technologic base for Federal, State, and local establishment of environmental standards for mining operations. Included in the minerals-processing-related work are projects to clean mineral-processing waters: demonstrate a Bureau process for scrubbing SO from powerplant stack :;as; recover dissolved minerals from process streams; stabilize discarded dusts, slags, and tailings: remove hazardous contaminates from byproduct wastes; reduce generation of waste solids; and improve metallurgical process engineering to eliminate pollution. Approximately $21 million was appropriated for this work in fiscal year 1981.

Jan 1, 1981