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By Manqiu Xu, Joe Holmes, Peter Wells, Peter Langlois, Germain Labonté, Jim Barrett

"The flowsheet for the Voisey’s Bay mill had to meet the challenge of processing an ore containing high pentlandite and chalcopyrite values in a largely pyrrhotite/troilite matrix. In the 1994-97 period, circuit development focused on making a high-grade copper concentrate and a relatively low-grade nickel concentrate. However, in 1998 a circuit with copper concentrate, high-grade nickel concentrate and a Ni/Cu middlings concentrate was specified. Following a three year project delay, work resumed on the flowsheet in 2001, and the target for the overall grade of the nickel concentrate was raised from 14% to 20% nickel. To achieve this target triethylamine tetramine (TETA) and sulfite pyrrhotite depressants were used in an all lime circuit. It later became evident that, with appropriate selection of collector and adjustment of the circuit by the addition of a scavenger on the scavenger cleaner, it would be possible to approach the grade of concentrate required without the use of pyrrhotite depressants. The recycle of water and the contained thiosalts was also proven to be instrumental in raising the grade.Construction and commissioning of the mill were fast-tracked with start-up of the mill in September 2005 some six months ahead of the original schedule. Ramp-up of both throughput and metallurgy was faster than any other recent nickel installations with tonnage being limited mainly by concentrate dewatering due to the higher than initially planned ore grades.INTRODUCTIONNickel was discovered in the vicinity of Voisey’s Bay by Chislett and Verbiski working for Diamond Field Resources in 1993 and the Ovoid deposit was delineated in the winter of 1994/95. By the end of 1995 the Ovoid had been well explored and at that time was thought to have a reserve of at least 30 million tonnes with an average grade of 2.83% Ni and 2.0% Cu. Drilling to the east of the Ovoid had indicated the presence of significant mineralization. In June of 1995, Inco Limited bought a 25% share in the Voisey’s Bay Nickel Company (VBNC) which was a subsidiary holding company set up by Diamond Fields. Inco also bought 8% of Diamond Fields and negotiated the right to sell all the nickel produced from VBNC for twenty years as part of this agreement. In April 1996, Inco bought the 75% of VBNC shares that it did not own."

Jan 1, 2007

The Army Reorganization Act, which became effective July 1, 1916, contains a provision authorizing the organization of an Officers' Reserve, in which will be included a Corps of Reserve Engineers. There will also be an Enlisted Reserve of skilled workmen in technical lines. The special provisions of the bill relating to the Engineer Officers' Reserve were formulated with the help of the Joint Committee of the several national engineering societies, which has been at work on the matter for over a year with the War Department and Committees of Congress. Recognizing that engineering science is the basis of success in modern

Jan 8, 1916

By S. Bellec, A. Berton

"Usually, steady state mass balances are used for the design of mineral processing plants. However, this tool does not take into account the impact of process inputs variability nor does it evaluate process transient behaviours between stationary states, such as mill start-up and shutdown. The use of advanced simulations enables the integration of dynamic behaviours in process design decision-making by highlighting situations that are undetectable by using only steady state mass balances. Applying these simulation tools to brown field projects allows the simulator performances to be calibrated and validated on actual plant data before it is used as a prediction tool for the modified plant.Three (3) simulators were implemented at the design stage of a major upgrade project for an ore processing plant in order to assess process behaviours under different production scenarios. These simulators were built to evaluate the impacts on major elements such as mine production, ore stockpile, concentrator production as well as water demand. A validation of individual equipment models was performed whenever sufficient measured data was available. The simulators were then used to study the impact of ore variability (grade, hardness, throughput), to assess day-to-day production special events, and to evaluate the true stockpiles live capacity.The use of a stochastic simulator for equipment sizing allowed a more precise sizing of many pieces of equipment and avoided important expenses in the fresh water pumping system. The dynamic simulator also confirmed that the water in place system would suffice, even in the most demanding production scenario. Finally, the stockpile simulator allowed an important production bottleneck to be quantified and then made possible the assessment of various practical solutions for the stockpiling-reclaiming issues.Post start-up, process data underlines the fact that using advanced simulation tools was useful to mitigate process-related risks associated to the plant expansion, showing generally accurate prediction and adequate equipment sizing, leading to smooth process commissioning. The presented methods are part of what is now routine in Soutex’s participation in both greenfield and brownfield projects."

Jan 1, 2015

By Paul G. Schmidt

The Crandon massive sulfide deposit Forest County, Wisconsin, was discovered by Exxon Minerals Company, U.S.A., in July 1975. Announced estimated in-place reserves are 62 M metric tons (70 million short tons), grading about 5% zinc and 1% copper. The reserves are evenly divided between massive sulfide are and stringer sulfide ore. The sulfide body is associated with Precambrian felsic pyroclastic rocks, and it is overlain by intermediate volcanic rocks and their derived sedimentary rocks. These rocks were subjected to greenschist facies metamorphism and were tilted to a near-vertical attitude. Geologic observations indicate a submarine-volcanic-exhalative origin for this deposit.

Jan 1, 1978

By Harry H. Power

WHILE the attention of all engineering branches is focused today on changes and improvements in the several curricula, we are concerned here with the many questions arising in industry and college concerning the preparation for the petroleum engineering profession. The succession of problems confronting the petroleum engineer demands a degree of versatility not ordinarily encountered in other professions. As a consequence, the student cannot acquire mastery of all the several engineering branches represented in field practice, and as an alternative, he has learned to appreciate the value of thorough training in the basic or fundamental sciences as a preliminary foundation for professional work. While our attention is directed primarily to the training of engineers in educational institutions, it is necessary that the ultimate education of the professional engineer be kept in mind. It is apparent that his success as an engineer is limited not only by his educational and job experience, but by his native endowments: mentality, personality and health. The engineer's lack of job experiences often proves as much a handicap as the lack of adequate college training. If the final product proves to be satisfactory, both industry and technical institutions are to be congratulated. However, if the product is found wanting, the one most responsible should be apprehended. FITNESS FOR PROFESSION For the most part, students of engineering colleges have had their interests in applied science awakened at a relatively early age. Many of them entered college as a convenient means of acquiring a technical education, but undoubtedly would have had better prospects in a shorter program offered by institutions of noncollege grade. The activating motive of practical interest is also strong in students suitable for college training, but in many cases an intellectual interest must be awakened in order that it may survive graduation. Numerous engineers believe that this progressive process of selection and determination of career aims is one of the essential services rendered by the engineering colleges. Industrialists, who are more interested in quality than quantity of petroleum engineering graduates, have pointed out the good that should result if more empha¬sis were given to the work of eliminating the misfits. They also point out the protective measures that have been taken by other professions for the betterment of professional standards. Mention has been made of the beneficial results to be obtained by collective determination of the market for the products of engineering schools, particularly in that the students unsuited to the profession would have an opportunity to prepare themselves for employment more suited to their personalities and other qualifications. In the event that such a system of coordinated personnel direction is developed by the

Jan 1, 1941

By Craig Bournes, David Chapman, Michael DiPonio

Historically, boulders are a frequent source of problems in soft ground tunneling. During tunnel construction, the need to manually break and remove boulders as obstructions causes delays to the project. Repairs to a tunnel boring machine (TBM) can also be a source of delays. Managing these problems is difficult since normal soil investigation techniques do not accurately predict the presence or frequency of boulders. This has lead to considerable number of claims for extra costs and delays during the construction of soft ground tunneling projects. These issues are exacerbated in pressurized face tunneling systems where there is limited access to the TBM cutterhead for obstruction removal and/or cutterhead maintenance. The project team that built the Big Walnut Augmentation/Rickenbacker Interceptor (BWARI) Project for the City of Columbus successfully managed the design and construction of a 4,267 mm (14 ft) diameter soft ground tunnel with high boulder concentrations in a complex geologic setting. The management of the boulder issue tookplace during several phases of the project.

Jan 1, 2007

By Walter Miller

BY the beginning of 1945 the output of petroleum products for war had reached a volume and a rate of growth which practically assured all requirements so long as war continued. The programs for making gasoline, lubricating oils of required quality, toluene for T.N.T., and chemicals for manufacture of synthetic rubber, as well as numerous other lesser petroleum products, were all well in hand, and unless catastrophic developments occurred there was no doubt of the ability of the industry to meet all demands. The end of the fighting found the refining industry working at top capacity on war commodities, but also in position to convert quickly into peacetime civilian production. 100-octane Aviation Gasoline Production of the vital 100-octane aviation gasoline, starting with approximately 44,000- bbl. daily capacity at our entry into the war, reached a top of 525,000 bbl. a day in the United States by the end of hostilities. With 75,- bbl. from other Allied sources, the grand total was 600,000 bbl., or 25,000,000 gal. each 24 hr. available to the armed forces had fighting continued. At times it was a close race between requirements and production, but never were any important military operations involving the use of high-octane aviation gasoline held up or delayed for lack of sufficient output of such material. The undivided effort of the entire refining industry in full cooperation with the Government made this record possible. Little diminution in output followed the German surrender on May 7. Plans called for a correspondingly greater activity for the Japanese war and possibly for well into 1946. But when the Japanese sued for peace on Aug. 10 most contracts were quickly canceled. Substantial stocks, reputed to be somewhere between 20,000,000 to 30,000,000 bbl., built up largely between V-E and V-J day pending organization of the larger Japanese war program envisaged after Germany gave up, were in the Government's hands in this country, in addition to working stocks in the war areas. Toluene and Lubricating Oil Requirements for toluene for T.N.T. increased rapidly as bombing speeded UP with increasing control of the air by the Allies in Europe and Asia. Production in excess of T.N.T. requirements which had been going into 1000-Octane aviation fuel blending during 1943 and 1944 was again drawn into explosive manufacture early in 1945. In anticipation of the war continuing into 1946, two new plants were ordered constructed, the decision being announced in April, plans calling for one of them to get into production about the end of 1945, the other in the first quarter of 1946. Both of these projects were later canceled as victory made it evident that the additional supplies would not be needed. Production was

Jan 1, 1946

By Raymond E. Kary, John W. Mcklveen

The four unit Cholla coal fired power station at Joseph City, Arizona, consumes coal from the McKinley mine located in western New Mexico. Since coals may contain relatively high uranium or thorium concentrations and may release quantities of detrimental progeny of these elements to the environs, there is concern that releases may pose an adverse environmental impact or even a health hazard to the workers. Thus, an effort was made to quantify the radionuclide content of the coal and compare the results with radionuclide concentrations already present in the vicinity of the plant. Additionally an attempt was made to assess any potential for significant enhancement of the levels of radioactivity in the environment or to plant personnel. Background gamma radiation measurements at and near the plant ranged from 8 to 12 [µ]R/hr (70 to 105 mR/yr) with a few localized anomolies measuring to 18 [u]R/hr (160 mR/yr). Levels on top of the coal storage piles decreased to ~ 6.5 [u]R/hr (60 mR/yr). Apparently the direct radiation emitted from the coal is less than the background levels in the vicinity of the plant. Measurements performed on top of several coal seams at the mine confirmed low radiation levels emanating from coal, but readings more than doubled when the overburden was monitored. Laboratory gamma spectrometry confirmed the lower amounts of natural radioactivity in the coal when compared against soil and water samples obtained in the vicinity of the plant and the overburden at the mine. In an effort to see if there is biological enhancement, animal feces was sampled. The radiation variations were found to be influenced primarily by naturally occurring potassium-40 which varied from ~ 1 to 18 pCi/gm rather than fluctuations in the uranium and thorium series. The potassium-40 concentrated in the ash were similar to the concentrations in the environs around the disposal ponds while Radium-226 concentrated in the fly ash was ~ 3 times that found in the immediate surroundings. Radon-222 gas concentrations in buildings at or near the plant ranged from 0.5 to 1.8 pCi/l and were generally lower than indoor concentrations measured in the Phoenix area. The burning of coal at the Cholla station does not appear to increase ambient levels of radioactivity found in the surrounding environs or to the workers. However, the use of byproduct fly ash for construction purposes may need to be examined.

Jan 1, 1981

By Jeffrey M. Taylor, Arturo Ressi di Cervia

"Construction of the drilled shafts for the Brightman Street Bridge Replacement Project were not only challenging due to working over the water but were also challenged by changed soil conditions, concurrent work being performed by an adjacent contractor on the same project, environmental restrictions and severe winter conditions. A total of 36 x 8 foot (2.44m) diameter drilled shafts with 7.5 foot (2.31m) rock sockets were installed for the East and West bascule piers. This project also included Osterberg Cell load testing on two production drilled shafts at both the East and West bascule piers. The results from the load test program were used to fine tune the design of the drilled shaft rock sockets. From a constructability standpoint the reverse circulation drilling method with a pile top drill rig proved to be an excellent choice for drilling the overburden and rock sockets of the large diameter deep drilled shafts. INTRODUCTIONThe replacement Brightman Street Bridge spans the Taunton River between Fall River and Somerset in Massachusetts.The new crossing is located approximately 1500 feet (450m) upstream from the existing Brightman Street Bridge, which was built in 1908. The new mainline bridge includes nine spans totaling 1725 feet (525m). A bascule type moveable span will be located in the middle of the Taunton River and provide a 200 foot (61m) open channel centered about the 400 foot (122m) navigational channel. The bascule span, which has a span length of 409 feet (124.7m), will be a trunnion-type four leaf structure with a solid deck. A site plan is shown in Figure 1 Contract 3, which includes construction of the foundations for the East and West bascule piers, was bid on December 19, 2000 and was awarded to Modern Continental Construction Company (MCC) on January 24, 2001. MCC in turn awarded the subcontract for the installation of the drilled shafts to TREVIICOS Corporation, which started mobilizing in June of 2001.The scope of work for the drilled shafts of Contract 3 consisted in installing 18 drilled shafts in three rows on each side of the river to support the bascule piers located in the middle of the Taunton River.The foundation plan for the bascule span is shown in Figure 2."

Jan 1, 2004

By P. K. Foster, C. M. Payne, A. McNabb

Some measurements of the rate of loss of hydrogen from cylinders of iron and steel are analyzed in terrns of a trapping theory. The apeement is encozcraging and gives rise to estimates for the density of traps in the metal. Furthermore, the results appear to be consistent with the assumption that the diffusion constant D for the steady flux of hydrogen through iron lies on the extrapolation of the linear curve (log D us 1/T) obtained at higher temperatures. IT has been shown in a previous paper1 that the literature relating to hydrogen diffusion in steels contains sufficient evidence to invalidate the application of Fick's laws to hydrogen diffusion in steel at low temperatures. To account for the deviations from simple diffusion behavior a trapping theory was developed, and the fundamental laws modified accordingly. In the present paper, new data on the evolution of hydrogen from long cylinders are presented, and together with some published data are examined in terms of the requirements of the theory.' Properties of solutions of the basic equations derived previously1 and appropriate to the present experimental conditions are outlined in the first section as they determine the form in which the experimental data must be presented for a comparison of theory and experiment. Two new solutions not previously reported have been derived as described in the Appendix. The experiments and treatment of data are then given in Sections 2 and 3 and the results are discussed in Section 4. 1) THEORETICAL CONSIDERATIONS The hydrogen-diffusion theory1 applied in this paper postulated that lattice-dissolved hydrogen at a concentration C diffuses randomly in accordance with Fick's first law, but that the lattice contains a uniform density N of traps which can capture and delay hydrogen atoms. kC atoms are trapped per second in a region containing unit concentration of vacant traps while p are released per second in a region containing unit concentration of occupied traps. On this basis it was shown (Eq. [30] of Ref. 1) that, when local changes in the lattice-dissolved concentration C are slow enough for equilibrium to be established with the traps, the system is represented in dimensionless form by the equation:

Jan 1, 1965

By Paul C. Schmall, Arthur B. Corwin, Hugh S. Lacy, Derek Maishman

For reasons of hydraulic design and constructability, water supply tunnel systems are often located relatively deep, in competent rock. Where the rock lies below a thick cover of water bearing soils, artificial ground freezing offers a low risk, cost-effective method of constructing access shafts. Several examples, in Kansas City, MO and in Brooklyn and Queens, NY, illustrate the use of freezing to provide structural support and ground water exclusion. In the case histories presented, the shafts range from 6m to 12m (20 to 40 ft) in diameter and soils vary from clays to boulder beds with depths in excess of 73m (240 ft) to competent bedrock. Where tunnels for infrastructure are designed to be driven in rock, vertical access may encounter a considerable thickness of overburden soils with groundwater. In such cases, shaft sinking problems are analogous to those confronted by mining engineers over 100 years ago. At that time, newly developed refrigeration machines were set to freeze the ground water and stabilize running sands. Although modern technology has refined our efforts, the basic features of the ground freezing to be described here are the same as those used in the last century. Vertical holes drilled on a circle surrounding the shaft site are equipped with leak-free steelpipes through which a refrigerated brine is circulated. In this manner, a frozen cylinder, seated in rock, is formed when the earth freezes between adjacent pipes. Shaft excavations take place inside a self-supporting, ground-water excluding structure. For mines, no better method of sinking production shafts through deepwater-bearing ground has yet been established. Indeed, major deposits of coal, potash, and salt would have remained inaccessible to this day were it not for the continued use of artificial ground freezing. If mine shaft freezing became relatively commonplace, early applications to civil engineering were few. Mussche and Waddington (1946) mention only five projects between 1892 and 1935; three of these relate to subway or vehicular tunnels in Paris, Antwerp, and (the most extensive) at five locations of the Moscow Metropolitan Railway development. In the United States, the method was used to spectacular effect in 1936, freezing about 3,000 cubic yards of silt to stop a slide

Jan 1, 1999

By F. E. Calkins

THE following presentation of the more important accumulated facts and probabilities involved in copper ore deposition is based on my experience in examination work and study of the extensive litera-ture of the subject; to make personal mention of all sources of information would require the naming of a small army of able geologists and other investigators who have contributed to, building up the science. I have tried to present the salient features of the subject in logical order and condensed form, and to point out the relative importance of processes involved. Doubt-less many geologists could suggest some changes and many additions. ORIGINAL SOURCE The original source of all copper was in the earth's interior; it has been brought to the outer part of the earth, within reach of man, in three ways: (1) By intrusions and flows of basic igneous rocks containing copper in minute quantities, presumably as silicate or sulfide. No orebodies have been formed by this method. (2) As segregations within intrusive igneous rocks, the copper minerals having solidified at the same time as the rock itself. The few deposits known to have been formed in this manner have been of little or no importance. The oft quoted Sudbury nickel-copper deposits are now known to belong to the class following. (3) By gaseous or liquid aqueous emanations from ,large deep-seated masses of intrusive molten rock. These emanations, or mineral solutions, ascended through zones of connected openings in the earth's crust and dropped their load at points far above their source. Deposits formed in this manner were the primary source of nearly all, if not all, of the world's copper production.

Jan 10, 1923

By Willard Jillson

WITHIN the last ten years Kentucky has become celebrated for its low-sulfur bituminous coals. Prior to this time, many investigators had discovered the abundance of this coal but the fact was unknown to the general public until the last extension of Kentucky's mountain railroads was completed. The coals of Kentucky are, broadly, separated into two geographic units-the eastern and the western coal fields. On a basis of their sulfur content these coal fields fall into three units, which are indicated on the accompanying map, by numbers, 1, 2, and 3. The area marked 1, the very southeastern part of the State, shows the lowest sulfur, all coals being averaged. In this field the maximum is 1.04 per cent. and the minimum as low as 0.68 per cent.-both averages and not individual analyses, which would of course show much greater variation. Included in this group are the following counties: Lawrence, 0.87 per cent.; Martin, 0.75 per cent.; Johnson, 0.73 per cent.; Magoffin, 0.S7 per cent.; Floyd, 0.88 per cent.; Pike, 0.68 per cent.; Knott, 1.04 per cent.; Perry, 0.77 per cent.; Letcher, 0.80 per cent.; Leslie, 0.70 per cent.; Harlan, 0.79 per cent.; Knox, 0.86 per cent.; and Bell, 0.92 per cent. The total average sulfur content for these thirteen counties is 0.82 per cent. Bordering the restricted low-sulfur field of eastern Kentucky is the No. 2 belt (slightly darker), which is commonly known as the western border of the eastern coal field. Here the maximum sulfur is 2.91 per cent. and the minimum 1.05 per cent. Again these are averages and not individual analyses. The counties in this group are: Greenup, 2.60 per cent.; Boyd, 1.67 per cent.; Carter, 1.07 per cent.; Morgan, 1.40 per cent.; Wolfe, 1.83 per cent.; Lee, 2.93 per cent.; Breathitt, 1.85. per cent.; Owsley, 1.09 per cent.; Jackson, 1.06 per cent.; Rockcastle, 2.30 per cent.; Clay, 1.09 per cent.; Laurel, 1.08 per cent.; Pulaski, 2.24 per cent.; Whitley, 1.05 per cent.; McCreary, 1.50 per cent.; and Wayne. The sulfur percentage average for this area including fifteen important counties is 1.65 per cent.

Jan 9, 1919

By Y. S. Li

The life cycle assessment method is applied to investigate the environmental impacts of cop-per-slag and copper-ore concentration process. Some environmental load data of copper production are obtained. The result indicates that damage level of human health, ecosystem quality and re-sources respectively is 0.174, 0.0203, 0.246 in the copper-slag concentration and 0.112, 0.0136, 0.299 in the copper-ore concentration. Environmental impact of copper-slag production (0.44) is more than that of copper-ore production (0.42), but can meet the environmental protect demand. With domestic copper concentrate supply gap enlarging, recovering copper from slag will lead to a significant improving of resource utilization and development of circulation economics.

Jan 1, 2014

By Dennis C. Martin

Construction of the Cerro Colorado on-off leach pad in northern Chile required about 3 Mm2 (32.3 million sq ft) of fill over an area of about 600,000 m2 (6.5 million sq ft) in irregular terrain with relief of up to 40 m (130 ft). Earthwork construction was completed in about six months using mine waste, placed in 4 to 6 m (13 to 20 ft) lifts with mine haul trucks. The lift thickness was reduced and the compactive effort increased in the upper 10 m (33 ft). This was done to develop a mat for additional resistance to possible differential settlements due to the modest density of the fill and dynamic (earthquake) conditions. A single 2-mm (80-mil) high-density polyethylene (HDPE) liner was used below the leach pads. This was protected from the loading and unloading equipment by bedding and cover systems. It consisted of screened sand, gravel and silt as the bedding and cover layers and a heel of screened gravel and primary crushed low-grade ore.

Jan 1, 1995

By W. D. Eddy

Topaz is a fluorine-bearing aluminosilicate mineral of the kyanite-sillimanite group. The formula has been given as Al2SiO4(F,OH)2, [Al(F, OH)]2SiO4, or 2Al2O3?2Al(F, OH)3SiO2. Topaz is generally considered a semiprecious-to-precious gem mineral, but it is a fairly common minor constituent of granites. In 1937 the U.s. Geological Survey reported an occurrence of massive topaz in the 3 Brewer gold mine, Chesterfield County, S.C. Over the next 8 years considerable research was done on topaz to establish its properties and to determine possible end uses The first reported shipment of ore was in 1939 Peak production was reached in 194412, and output then began declining until the mine closed in 194913? During World War II topaz was used in refractories, as a flux in steel mills, and in the manufacture of borosilicate glass 14. The main advantage of using topaz over kyanite and sillimanite in refractory use was that calcined topaz converted to over 95 percent mullite (3A1203 .2Si02) while calcined kyanite or sillimanite contained only 88 percent mullite15. However, a major draw-back to utilization of topaz is the evolution of fluorides during calcination. In 1973 the Geological Survey reported that topaz occurred in probable commercial quantities in at least two domestic locationsl6: the Brewer area of South Carolina and a location in Colorado. The literature also indicated that progress had been made in controlling fluorine-bearing fumes. This research has progressed to the state where valuable fluorine compounds are being recovered on a commercial scale 17. Thus, a major obstacle to utilization of topaz appears to have been resolved. The Bureau of Mines under its program of advancing minerals technology initiated a project to study techniques for the concentration of topaz from disseminated materials. The objective of the study was to determine those techniques that would be used to produce topaz concentrates that could be utilized as a source of fluorine and mullite.

Jan 1, 1977

By J. Olson

"A model was developed to use near-infrared (NIR) analysis of pulverized ore samples to estimate the recoverable gold content for ores from the Barrick Cortez Hills underground mine. Current routing practices use a ratio of the cyanide soluble gold content and fire assayed gold (CN/FA) to classify ores as oxide or refractory. Prediction accuracy of the NIR model was equivalent to the CN/FA ratio. Prediction accuracy was improved by combining the CN/FA ratio and the NIR spectra. Bootstrap validation estimates the root-mean-square error to be 9.92% with an estimated r-squared value of 0.893. This model will allow more accurate estimates of the variability in recoverable gold content throughout this mine. These data will aid in building an improved geo-metallurgical model or in making better informed routing decisions during the production cycle.INTRODUCTION The contained gold of an ore available for cyanidation is often related to subtle variations in the mineralogy. It is difficult and expensive to collect enough mineralogical information in order to predict how the variable mineralogy will impact the metallurgical results and project economics throughout the life of the mine or mill. Near-infrared spectroscopy may be an effective tool to rapidly and inexpensively collect discrete, quantitative mineralogical data for minerals that contain transition metal oxides, metal sulfides with semi-conduction properties, rare earth metals, and some chemical groups having di-pole covalent bonds such as carbonates, sulfates, and various types of clays (Hunt, 1977). Near-infrared spectroscopy can be a powerful tool for geo-metallurgical characterization of deposits where the presence of these minerals has direct or indirect relationships to metallurgical results such as grindability, regent consumption, or recovery. Near infrared spectroscopy is a rapid analysis that measures the intensity of reflected light in the near-infrared spectrum. The ranges for the ASD-Panalytical units used in this study extend through the visible spectrum and into part of the UV spectrum, reporting reflection by wavelength from between 350 nm to 2500 nm. Absorption peaks visible in this range are a result of interactions with outer valence elections or chemical bonds. The location and intensity of the peaks vary depending on the chemical composition and crystal structure of a solid indicating the presence and abundance certain minerals (Hunt, 1977; Clark, 1984)."

Jan 1, 2017

By M. J. Wilhelm

Bromine is the intermediate member of the halogen family of elements between iodine, a solid, and chlorine, a gas. The name is derived from the Greek bromos, meaning stench. Bromine is the only nonmetallic element that is liquid at room temperatures, with a melting point of -7.2°C and a boiling point of 58.78°C. Reddish brown in color, it dissolves easily in water to yield a red solution. Bromine volatilizes at ordinary temperatures to a red vapor that is very irritating to the eyes, nose, and throat. Density of the liquid is 3.12, and gas weighs 7.59 gpl in standard conditions. Because the element is highly active, it exists in nature only as bromide compounds. Bromine was discovered by Antoine Jerome Balard in seawater bitterns in 1825 and began to find commercial applications shortly thereafter in photography, medicine, and dyes. The first commercial production of bromine was in 1846 in Freeport, PA, followed by production in Germany in 1865. OCCURRENCE Bromine is widely distributed in nature, and compounds occur in solution in natural brines, in seawater, saline lakes, oil and gas well brines, and in evaporite chloride minerals. The concentration of bromine salts ranges from 60 to 65 ppm in seawater to several thousand ppm in oil well brines and saline lakes. The distribution of bromine in marine evaporite minerals and in the solutions from which they crystallized was determined many years ago by H.E. Boeke (1908). Theoretical aspects regarding the geochemistry of bromine have been published in numerous papers (Raup and Mite, 1969). Bromine occurs in solid solution in carnallite and sylvite associated in potash deposits, in halite in salt beds, salt in oil shales, and in trona deposits. Its presence is useful as a guide in geochemical exploration. The analysis of small amounts of bromides in the presence of large amounts of chlorides is discussed by W. Schwerdtner (1963). Manganese, iron, and iodine may interfere with the determination. Other analytical methods are discussed at length in literature (Stenger and Atchison, 1964).

Jan 1, 1994

By Leon H. Nelson

Several factors which affect the segregation and solidification of killed hot-topped steel ingots are: (1) pouring temperature, (2) volume in the hot top, (3) taper in the ingot, (4) pouring rate by varying the nozzle size, (5) segregation of several elements, (6) moving ingots before completely solidified. In most of this discussion, segregation will be measured in terms of carbon variation only. All the data given are results on S.A.E. 1040 analysis of fully killed steel direct-poured in hot-topped molds giving 20-in, square ingots. Thus the variables of analysis and ingot size and contour are eliminated. Segregation results are all on the rolled-bloom size, not on the ingot itself. They are results from plant-control work and not results of special research on ingot segregation. Pouring Temperature The temperature (or, more correctly, the amount of superheat above the liquidus-solidus) of the steel entering the ingot is, of course, one of the most important factors influencing segregation and solidification. Table 1 gives the average segregation of a number of heats of S.A.E. 1040 steel with normal pouring temperatures of 2775" to 2825" F. The table also gives some data on segregation in hot heats (pouring temperature 2840" to 2870" F.) and in cold heats with some skull (poured at 2725" to 2760" F.). The results in Table 1 are on steel ingots with 20-in. square cross section and 60 in. long to the hot top. The ingot weighs 7100 lb. and the hot top contains 14.3 per cent of the total ingot volume and 11.2 per cent of the total ingot weight. The results are from drillings after rolling the ingots to bloom size. Segregation results obtained on the bloom are probably not as great as they would be in the ingot itself, since heating the ingots for rolling can perhaps cause some migration of carbon from regions of high and low carbon to those of average carbon content.

Jan 1, 1937

The brown coal deposits of the Latrobe Valley are ideal for open cut mining and this method has been used since the start of coal winning in 1894. Operations at the main Yall9urn open cut commenced in 1922, but after a few years the main excavators were replaced by German continuous excavators and subsequent developments of Yallourn and the newer Morwell open cut have been based on this type of plant. The reasons for preferring continuous to intermittent excavators in the Latrobe Valley are indicated in this paper.Under the pressure of post-war conditions, and from their long experience and ability, German engineers have recently made substantial improvements in their continuous excavators and these developments have been enhanced by some American innovations. These changes have extended the economic limits of open cut mining and also serve to emphasize the close inter-relation between the nature of coal and overburden deposits, excavator design and methods of operation.As an aid to descriRing recent excavator developments, this interdependence is demonstrated by means of diagrams which show typical methods of operations, together with examples of actual machines using these methods. The types of excavator dealt with are mainly those in use at, or destined for Yallourn or Morwell open cuts, together with additional types used in U.S.A. and Western Europe. For completeness, and also because they will continue in service at Yallourn and Morwell for some years, rail-mounted dredgers have been included in this paper even though in Europe they are now regarded as obsolescent.Explanations are given of how the intrinsic qualities of Latrobe Valley brown coal and overburden have sometimes prevented overseas plants from operating with the full efficiencies and/or in the methods visualized by the manufacturer, and references are made to the modifications and investigations being undertaken to overcome these problems.A compresensive bibliography is given. Dates shown on illustrations are not commissioning dates of the plant concerned, but the year when photographed.

Jan 1, 1960