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Modelling and Optimisation of Direct Reduction of Iron Ore by Coal in a Rotary Kiln

Sep 13, 2010

By M. M. Gadde

Recent regulatory changes in the United States make it mandatory to conduct structural analysis of coal mine seals used to isolate abandoned workings from active mining areas. Different loading criteria are available for seal design depending on whether gob composition is actively monitored and maintained or not and whether the gob conditions lead to deflagration or detonation type loading. Since the loads involved in seal designs are dynamic in nature, the structural analysis must be made using dynamic stress analysis techniques. However, because of the significant complexities involved in conducting dynamic analyses, some designers use approximate simplified techniques to address the design problem. In this paper two such simplified methods are critically evaluated for their suitability to design coal mine seals. The benefits and limitations of the simplified methods are also outlined. Some comparisons are made to show the differences between sophisticated three dimensional dynamic analyses and the simplified methods and to delineate the problems associated with the latter approaches.

Jan 1, 2009

All aspects of precious metals processing were featured at a symposium held Oct. 3-6, 2007, at Loews Ventana Canyon Resort in Tucson, AZ. Although billed as "Precious Metals Processing: Advances in Primary and Secondary Operations," the symposium also looked at economic, regulatory and environmental issues affecting the precious metals industry. The symposium was sponsored by SME; The Minerals, Metals & Materials Society (TMS); and the International Precious Metals Institute (IPMI). It included workshops, technical presentations, guest speakers and social activities. Mining industry management, process engineers, equipment manufacturers, consultants, metals marketers, academics and others involved in the precious metals industry attended the conference. Needless to say, with gold nearing $25.721g ($800/oz) and platinum pushing $41.801g ($1,300/oz) at the time of the meeting, the mood among the attendees could not have been more positive. The symposium was privileged to have Father Ernest S. Sweeney, professor of Latin American History at Loyola Marymount University, as a guest speaker. Sweeney, a Jesuit priest, provided a colorful account of the history of mining in Arizona and the surrounding region of North America (Fig. 1). He described the importance of the mining industry and said, "To go down into the bowels of the earth to extract its riches for the benefit of all of us is an awesome task deserving our sincere respect and gratitude." However, he warned the industry that: "The ever increasing de¬mands on the mining community for the protection of the environment calls for endless efforts to maintain ethical standards in a business filled with risk, uncertainty and frustrations." Sweeney noted that the Spanish conquest of the Americas was driven by the three fundamental motives of "God, glory and gold." He noted that gold was the basic, most powerful driving force of the conquest and occupation of the Spanish empire. The first European to explore Arizona was the Franciscan missionary Marcos de Niza. He came to Arizona in 1539 in search of the fabled Seven Golden Cities of Cíbola. Sweeny noted that Spanish explorers were consumed, as Cortes himself described it, "with a burning fever that only gold could cure." Sweeney told the story of some of these early explorers, including Francisco Vázquez de Coronado who "mounted an expedition in pursuit of gold and rich empires to conquer." Coronado passed through Arizona and discovered the Grand Canyon. "Coronado returned to Mexico exhausted, bankrupt and disillusioned, but with a wealth of new knowledge of the borderlands of the Spanish empire," said Sweeney. He then described the colorful history of early gold, silver and copper exploration and mining in Arizona, including the famous tale of the Lost Dutchman's Mine. In a luncheon address, David Kanagy, SME's executive director, introduced the attendees to the upcoming OneMine. org Web site. Kanagy told the audience" One-Mine.org will be a collaborative digital library that will

Jan 1, 2008

By Raj K. Rajamani, Sanjeeva Latchireddi, Dave Plummer, Stieger. Julius

"The Cortez SAG mill liner design was recently modified to improve the mill operating energy efficiency. In addition to the expected benefits, the design change unexpectedly played a significant role of verifying the proposed grinding circuit expansion for the Cortez Hills project as well as illustrating current SAG mill bottlenecks. This paper will discuss the evaluation that addressed operator and maintenance observations, historical PLC data, and “crash stop” observations to calculate charge motion, packing between lifters, and slurry transport through grate and pulp lifters. The performance of the new shell and discharge end liner design will also be discussed as well as their role in the possible grinding circuit expansion.INTRODUCTIONCortez Gold Mines commenced operation in 1969 with its Mill #1 rated at a nominal 2,000 tons per day. Mill #1 was a conventional rod mill/ball mill circuit followed by an 8-stage CIP circuit. In the early 1990s the Pipeline deposit was discovered and subsequently Mill #2 was built to process the increased ore volume. Mill #2, commissioned by mid-1997, was a nominal 10,000 tons per day SABC circuit followed by an 8-stage CIL circuit for oxide gold ore. Operating and commissioning details of this plant have been published elsewhere (Powell, 1998). By late 1998, there was not enough ore volume to support both mills so the smaller, higher operating cost Mill #1 was put under its current care-and-maintenance status. A simplified flowsheet of the current mill is shown in Figure 1."

Jan 1, 2007

By Chand F

The silver deposits of Rockvale near Armidale, N.S.W., occur in fissure veins in epi-Permian granite. The ore is fine grained, mineralogically complex, and contains twenty-seven different minerals including eleven silver minerals. The ore is characterized by a unique multiple unmixing from a sphalerite solvent. The following minerals have exsolved from solid solution in sphalerite: pyrrhotite, chalcopyrite, cubanite I, cubanite II (chalcopyrrhotite), valleriite, "brown" stannite, "olive" stannite, argentian tetrahedrite, pyrargyrite, and an unknown grey-white mineral. Several of these minerals derive from a second-stage unmixing, the immediate solvents of which are the products of earlier exsolutions.INTRODUCTIONSmall silver-rich base metal deposits occur at several localities near Armidale in the New England district of New South Wales. Chief among these are the Tulloch Mine and the Rockvale Mine at Rockvale, 27 miles SE. of Armidale, and the Tait's Gulley deposits some 15 miles NE. of Armidale.At Rockvale (Kenny, 1928), irregular lenses of lode material, principally quartz and calcite, occur along a zone of shearing in biotite granite and altered sediments. The orebodies had a maximum width of 6 ft but averaged 2 ft 6 in. The largest lens was 150 ft long and 50 ft high. The Rockvale deposits were worked for both arsenic and silver; 2,897 tons of arsenic were produced but no figures are available forsilver.Little is known of the Tait's Gulley deposits which occur in folded arenites containing small but rich veins of pyrargyrite with base metal sulphides.The sediments in these localities are possibly Silurian.

Jan 1, 1962

Most mining operations have been happy to live in blissful ignorance of what their equipment is really capable of. Shareholders have been shown increasing tonnes output per employee (due to rationalising employee numbers). It is now known that the best practice for large mining trucks is 52 per cent higher than average or best practice for excavators is 41 per cent higher than average, or 38 per cent in shovels or 35 per cent with draglines, etc. The data is available. The bell curve of performance is flat. Substantial underperformance is rife. If you are working in or supplying equipment or services to one of the majority of operating mines that donÆt achieve best practice surely you want to know why. Or maybe you donÆt? For many mining people this sort of knowledge could be dangerous to their career so keeping the MD or CEO in the dark is a good option. Many suppliers donÆt want the performance of their equipment benchmarked? Mining consultants donÆt have the data so they are happy to keep guessing. Unfortunately, many Business Improvement or Business Excellence projects are about ticking the participantÆs æcareer boxesÆ. The first step to capacity utilisation is knowing what the capacity is. Even then people and culture will get in the way. People are the biggest hurdle to capacity utilisation. This paper will discuss what the mine of the future (and today) will need to do to utilise the productive capacity of its assets. It is not just benchmarking. It is not just automation. It is not just technology. It is about engaging those people who impact on equipment performance; right from the operator up to the Mine Manager. Doing it better involves a process to facilitate change and a culture which says it is OK to try even if you are wrong.

Jan 1, 2009

By J B. Gemmell, D R. Cooke

Recent mapping at the Kelian epithermal gold deposit in East Kalimantan, Indonesia has delineated intrusive and extrusive-phreatomagmatic breccias, their magmatic roots, and late-stage endogenous domes of a maar-diatreme complex. The Kelian epithermal system is characterised by a wide variety of mineralised and unmineralised breccias, which include tectonic, hydrothermal, phreatic and phreatomagmatic varieties. Phreatomagmatic breccias and associated igneous rocks post-date early stage alteration and mineralisation, and pre-date main stage precious and base-metal mineralisation. This study emphasises the spatial, temporal and genetic links that have been drawn between diatremes and both epithermal and porphyry systems in volcano-plutonic arcs.

Jan 1, 1999

By B. Ndlovu

The world mineral industry has over the years experienced growth in the production of nickel (Ni) due to its use not only in the catalytic industry but mainly also to its demand in the stainless steel production industry. Hence there is a need to produce more pure and marketable grades of Ni through the use of efficient purification routes such as solvent extraction. The V10-LIX®84-IC system resulted in nickel (Ni) extraction isotherm shifting to lower pH levels. The pH window of opportunity for the extraction of Ni subsequently increased in solution containing magnesium (Mg) and calcium (Ca) even though the system also resulted in slight shifts to less positive pH values for Mg and Ca curves. Results showed a synergistic effect of LIX®84-IC when added to V10 for all elements, Ni, Mg and Ca. The pH50 values for elements Ni, Mg and Ca in the V10-LIX®84-IC system were 2.95, 8.10 and 7.70 respectively. Comparing results obtained when using V10 alone produced ?pH50 for Ni, Mg and Ca being 3.35, 0.15 and 0.70 respectively, which was a confirmation of the synergistic shifts for all the elements. The ?pH50 (Mg-Ni)value was 1.95 with no synergism and 5.15 with synergism and that for ?pH50 (Ca-Ni)was 2.10 with no synergism and 4.75 with synergism. This showed that the Ni-Mg separation factor was relatively larger than the Ni-Ca. Improved loading and stripping kinetics were also observed. Keywords: Nickel solvent extraction separation, magnesium, calcium, versatic 10 acid and LIX®84-IC.

Jan 1, 2008

By Michel R. Julien, Michel Lemieux, Jean Cayouette, Daniel Talbot

"The Louvicourt Mine located near Val d’Or, Quebec has been in operation since 1994. It produces copper and zinc concentrates. The tailings generated from the ore processing operations have a strong net acid generating potential. Louvicourt Mine, a grass root project, was designed for closure with the best available technology at the time of design. In order to inhibit short and long time acid potential generation, sub-aqueous disposal was selected at the design stage. Given the fact that disposal in a natural lake was ruled out up front for obvious reasons related to loss of natural habitat and risks of permitting delays, a man made facility built with dams was planned. This mine includes therefore the first fully man-made sub-aqueous tailings disposal facility built in Canada. The requirement of using sub-aqueous disposal had serious implications on the placement of tailings. This tailings facility located about 9 km from the mine site has been selected based on the available natural confinement, the favorable foundation and hydrogeological conditions. This paper describes the site and the design criteria that were used. A presentation is also made on the placement technique to maximize storage and its impact on the operation of the basin. The performance of the basin, the dams and the decant structures is reviewed.Résumé : La mine Louvicourt, située près de Val d’Or, Québec est opérationnelle depuis 1994. Elle produit des concentrés de cuivre et de zinc. Les résidus générés par les opérations de traitement du minerai possèdent un fort potentiel net de génération d’acide. Le parc à résidus de la mine Louvicourt, implanté dans un milieu naturel intact, fut doté dès sa conception initiale de la meilleure technologie de fermeture disponible à l’époque, soit la déposition sous couverture aqueuse et ce, dans le but de bloquer le potentiel de génération d’acide à court et à long terme des résidus. Etant donné que la déposition dans un lac naturel fut mise de côté dès le départ pour des raisons évidentes reliées à la perte d’habitats naturels et au risque d’introduire des délais dans l’émission des permis, un étang artificiel délimité par des digues a été conçu. Cette mine fut donc la première au Canada à être dotée d’une installation anthropique de disposition des résidus sous une pleine couverture aqueuse. L’exigence d’une déposition sous couverture aqueuse a eu des implications sur le mode de mise en place des résidus. L’emplacement de l’installation de gestion des résidus a été choisi en un lieu situé à environ 9 km du concentrateur sur la base du confinement naturel disponible et des conditions hydrogéologiques et géotechniques favorables. Cet article décrit le site et les critères de conception utilisés. Une présentation est faite sur la technique de mise en place utilisée pour maximiser l’entreposage et son impact sur l’opération du bassin. La performance du bassin, des digues et des structures de décantation est également revue."

Jan 1, 2004

By D S. Clarke, K B. Sporli

The Thames Goldfi.eld has been a major gold resource in the west of the Coromandel Peninsula, New Zealand, with the Waiotahi quartz vein system forming a large part of the field. Mineralisation is hosted by hydrothermally altered Miocene andesitic volcanic rocks. Both massive columnar-jointed and fragmental volcanic rocks are present. The vein system is dominated by the steeply dipping NE striking Waiotahi-Cambria vein, and associated splays. Hydrothermal alteration increases in intensity from isolated blocks of propylitic altered andesitic material, into the intensely clay altered equivalent. Low rank propylitic alteration is typified by chlorite, calcite and pyrite, with local illite or epidote. Clay alteration is characterised by illite, quartz, kaolinite and pyrite. While broadly forming halos around veining, intense clay alteration also occurs in strongly jointed portions of the hostrock.   Vein textures and the intense illitic clay alteration at Thames are similar to those in some of the other epithermal gold deposits of the Coromandel Volcanic zone, and in deposits of the Philippines, all related to andesitic terranes. Possible causes for textures and alteration being different in these deposits from the more classic Quartz-Adularia-Illite type epithermal systems may be that cooling/mixing rather than boiling dominates fluid evolution. Kaolinite may be also be a product of either of these different fluid types, or has resulted from overprinting of an illitic assemblage by downward percolation of acidic fluid.

Jan 1, 1991

By Stewart A. Silling, Dale S. Preece

The two key results of rock blasting are fragmentation and movement of geomaterials. Movement/flow of the blasted rock is often referred to as heave. Modeling the movement of full scale blasting is now possible with 3D distinct element models and parallel processing.

Jan 1, 2016

The rocks of Waihi and the surrounding district are almost entirely rhyolitic and ande5itic in character. Sedimentary rocks, with the exception of some surface deposits of clay loosely compacted conglomerate, etc., and one or two thin and broken beds of a very poor lignite, occasionally changed by igneous agencies into a bituminous coal, are almost absent. In the shafts sunk by the Waihi and Grand Junction companies outside the outcropping andesitic area of the Martha Hill, more than one old surface or lake bottom has been passed through. At these points layers of sand, consolidated volcanic mud and tuff, accompanied by numerous broken fragments of imperfectly silicified wood have been enccuntered, but these occurrences may, for the purpose of this paper, be neglected.The youngest rock of the district are rhyolites, probably of Pliocene age. At least three distinct classes of rhyolitic lava, each possessing features of unusual interest, may be made out. None of these, however, is gold-bearing. The youngest flow, a light-coloured, fine-grained rock, is remarkable owing to its enclosing at times fragments of carbonised wood, varying in size from mere specks up to quite large pieces of almost pure charcoal. Rhyolitic tuff is also met with. The rhyolites cover a large extent of nearly flat country east, south, and west of Waibi, here and there rising into barren, stony hills.Below the rhyolites, geologically speaking, but for the most part. forming hills which bound the rhyolitic plain, or rise out of it as isolated patches, come ahdesites of older...

Jan 1, 1902

By Wolfgang Gütter

India is targeting to boost its electrical capacity from 100 GW to 200 GW within the next 10 years. The National Hydroelectric Power Corporation (NHPC) has decided in2001 to take execution of the 800 MW Stage-II of the prestigious 2,051 MW Parbatihydrol electric project in Kulu district of the northern province Himachal Pradesh. Two parallel 30° inclined underground pressure shafts of 1.542m in length each will be excavated in different geological formations and lined with hexagonal concrete segments by a hard rock double shield TBM. That kind of heading will be a novelty to India and an innovative method for inclined pressure shafts. The 4.88m Mitsubishi DSTBM will be assembled underground on a swivelling steel platform especially designed for the launching as well as for the acceptance of the TBM in the upper cavern of each shaft. The hexagonal segmental lining system causes a significant higher job safety than an open TBM with conventional support. Each ring consists of four honeycomb segments with 20 cm thickness. After finalisation of the excavation a steel liner will be installed and concreted. The Joint Venture Jäger-Seli will perform the two pressure shafts as a sub-contractor for the Indian company Gammon India Ltd.

Jan 1, 2005

Mining education has received almost continuous discussion since its inception and most people engaged in the mining industry and in mining education feel at some time the urge and necessity to express their views. This paper is not a comprehensive survey of past and present practices and accepted principles, but a personal opinion of the form mining education should take at university level. It is expressed because of a dissatisfaction with the existing courses offered to students. It is hoped to provoke discussionand bring forth guidance to those engaged in mining education. After all, students spend four or five years at a university and it is desirable that the graduate should be something more than just those many years older at the end of his course.POST GRADUATE EMPLOYMENTThe first problem confronting the university should, be to discover what the mining industry wants and expects or graduates. This must influence the university course and yet universities have done little to seek this information, and if suggestions have been offered by industry; universities appear to have made little use of them. University mining curricula are basically what they were 50, 100 and even 200 years ago. (See Appendix.) Whether this reflects the unchanging problems of mining the wisdom of early professors, the conservatism of subsequent professors or inability to apprectate necessity for changes, is debatable.Unfortunately there is no uniformity in the type of employment offered to new graduates: Some mining...

Jan 1, 1959

There is an alternative theory of the high grade orebodies of the Middleback Group, based on the primary nature of the high grade ores in an area of carbonate deposition, with lesser amounts of siliceous and aluminous sediments. The environment is thought to have been unstable, possibly volcanic, and to have been a subsiding basin, substantially isolated from the open sea.Jaspilites, iron bearing talc rocks and iron bearing carbonate rocks were derived from the primary sediments by metasomatic alteration after metamorphism.The metasomatic agents were carbon dioxide and water vapour which were mobilized from the primary dolomite and reacted with a metamorphically produced group of iron bearing and iron free amphiboles, forming talc and progressively releasing silica and iron oxides from the iron amphiboles.The talc rocks in turn released silica which reconstituted jaspilites into their present 200 ft thick crust or zone.The theory accounts for the present disposition of a jaspilite zone over a talc zone which in turn overlies a carbonate zone, and accounts for the down dip changes found in bores which penetrate these zones.INTRODUCTIONIron Duke (Fig. 1) lies some 34 miles south west of WhyalIa in South Australia, and is the most southerly ore body in the Middleback Ranges.The Middleback Ranges are divided into a northern range and a southern range meridionally disposed and separated by an erosion gap called Kimba Gap.The South Middleback Range contains four orebodies;Iron Duke at the southern extremity, Iron Duchess north of Iron Duke and on the same ridge, Iron Knight also on the same ridge, which has been breached by erosion between theDuchess and Knight orebodies, and north east of Iron Knight, the Iron Chieftain.Cook's Range is the eastern range of the South Middleback Range and no large orebodies are known to occur there.

Jan 1, 1963

By Dupuy. Leon W., R. T. C. Rasmussen, W. A. Calhoun

"INTRODUCTION For many years it has been known that low-grade manganese deposits occur in the bluffs along the Missouri River Valley. Frequent attempts have been made to develop the ore and to produce a marketalble commodity but they have had little success. Under pressure of the war emergency and the shortage of manganese, the attention of the Federal Bureau of Mines was directedtoward the deposits.Manganese-bearing shale occurs from a point near Pierre, S. Dak., down the river to the Rosebud bridge near the Nebraska line (1).5/ The Bureau of,confined its work to the more accessible central portion of the deposits near Chamberlain, S. Dak. The ore occurs principally as concretionary nodules in the form of iron and manganese carbonates (manganosiarite and perhaps some manganocalcite; rhodochrosite has not been identified). At the surface the carbonate is often broken down so that the oxide of manganese gives the nodules a black The matrix or host rock is generally known as Pierre shale, composed of ""interbedded layers of bentonite, an altered volcanic ash, and dissemi¬nated bentonite particles,"" (2) and montmorillonite-beidellite clay minerals (3). The shale weathers to the very sticky gumbo characteristic of South Dakota and well-known to hunters and travelers in the area.The area selected for the experimental mining and pilot-plant work discussed in this report lies about 8 miles westerly from Chamberlain and is a few hundred feet north of U. S. Highway,16, on land owned or controlled,by M. Q. Sharpe of Kennebec, S. Dak., and the General Manganese Corp."

Feb 1, 1946

By Kefton H. Teague

This paper deals with the practical application of the Dutch State Mines cyclone separator for fine-coal cleaning. The more important operating variables are discussed, and results of a number of continuous-scale tests on various fine coals with a 6-in. cyclone separator are given. Descriptions of the Cyanamid Pilot Plant and the 50 tph Cyclone Separator Plant at the Emma Washery in Holland are included.

Jan 1, 1950

By John Chipman, Peter J. Koros

The distribution of copper between liquid silver and liquid iron, Fe-C, and Fe-C-Si alloys was studied at 1600°C. From the data and the activity of copper in silver obtained from the phase diagrams, the activity coefficients of copper in iron up to 3 atomic pct are log y, = 0.90 — 2.4 N, and y": = 8.0. The effect of carbon up to saturation is expressed as log y = 1.8 Ni. The effect of silicon up to 11 atomic pct is insignificant. SLOWLY rising copper content of steel being produced is focusing attention on the lack of information on the behavior of copper in liquid steel. Chou' measured the activity coefficient of copper in liquid iron through its distribution between liquid silver and iron. He obtained a value of 9.12 at infinite dilution. Chipman' calculated the activity coefficient of copper in liquid iron at 1600°C from the phase diagram and obtained a value of 12. Ameiln and Pfeiffer- investigated the possibility of removing copper from liquid steel through the use of lead, silver, and bismuth as solvents. They also calculated that the activity coefficient of copper in liquid iron would be increased five or sixfold by addition of 4 pct C. Langenberg and Lindsay' are investigating the effectiveness of lead and sodium sulfide in removing copper from liquid iron. The experimental method was similar to that used by Chou' and Chipman and Floridis." Silver, copper, and iron were melted together, the copper distributing itself between the two layers so that at equilibrium a,.,, (in Ag) - a,.,, (inFe) and N,.,, (in Ag) yc,, (inFe) (in Ag). [21 N,.,, (inFe) Thus, from the concentration of copper in each layer and the activity coefficient of copper in liquid silver, the activity coefficient of copper in liquid iron can be calculated. The effect of an alloying element such as carbon on the activity coefficient of copper can also be determined from its effect on the distribution, provided the new element is essentially insoluble in silver. The one serious limitation of this method is the increasing mutual solubility of silver and iron in the presence of a third component. The mutual solubilities of pure iron and silver are negligible, but increase with increasing copper concentration beyond the range investigated. Ag-Cu System—The activity coefficient of copper in silver at 1600°C had to be estimated, since direct experimental data are not available. Kawakami" measured the heat of mixing of Ag-Cu alloys at 1200°C by a calorimetric technique. Scheil' calculated the heat of mixing in this system by use of the phase diagram, assuming that the solution is random and that the heat of mixing is independent of temperature. The terminal solid solution may be assumed to obey Raoult's law within the requirements

Jan 1, 1957

By P. den Hoed, R. I. Rambiyana

"Four sulphide minerals - pyrite (FeS2), pyrrhotite (Fe1-xS), pentlandite ([Ni,Fe]9S8), and chalcopyrite (CuFeS2) - contain the base metals and most of the iron in concentrates of platinum group metals (PGMs). In the pyrometallurgical processing of PGM concentrates these sulphides form a matte during smelting, and iron and sulphur are removed from the matte during the converting process. This paper discusses the roasting of Merensky concentrate in air before smelting, with the purpose of reducing the matte load to the converter.Roasting tests were conducted in a bench-scale rotary kiln at temperatures from 350°C to 700°C. The concentrate tested contained 17.4% sulphur and consisted of 23% pyrrhotite, 16% pentlandite, 11% chalcopyrite, and 2% pyrite. The particles were fine (d50 = 22 µm), and all the sulphide particles were liberated. Roasting in air at 550°C and 650°C for 20 minutes removed respectively 60% and 70% of the sulphur. The iron in the sulphides was oxidized to Fe3O4 (magnetite) at temperatures below 500°C and to Fe2O3 (haematite) at temperatures above 550°C. At 700°C the bed sintered and copper oxides formed. At temperatures below 450°C oxidation was incomplete: pyrrhotite remained and only 30% of the sulphur was removed. Smelting tests were conducted to assess matte fall and the deportment of copper and nickel to matte. It was evident that roasting resulted in lower matte falls (a drop of approximately 60%) compared with matte falls from unroasted concentrate. The iron and sulphur levels in the matte were reduced to below 3.5% and 22% respectively.This paper also briefly describes the mechanisms by which pyrrhotite, chalcopyrite, and pentlandite are oxidized during roasting. For chalcopyrite, the mechanism proceeds through an intermediate solid solution phase, which extends from Cu1.02Fe1.04S2 to Cu2.04Fe0.72S2 to a copper-rich solid solution of bornite (Cu4Fe1.4S4-Cu2S). The oxidation of pentlandite proceeds through a monosulphide solid solution (Ni0.39Fe0.53S-Ni0.74Fe0.15S) to a solid solution of heazlewoodite ([Ni,Fe]3}xS2). These mechanisms are explored in relation to chemical thermodynamics and microstructures."

Jan 1, 2015

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