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The Rosebery and Hercules mines, situated in the Rosebery-Williamsford district in western Tasmania, have a history of production dating back to 1896-7, although full scale production did not commence until 1936, following the development of a satisfactory process of selective flotation (Hall, Cottle, Rosenhain and McGhie, 1953). The mineral composition of the Rosebery zinc-lead ores was first described in detail by Stillwell (1934). The Hercules ore is generally similar, but as yet no descriptions of it have beenpublished.Since Dr. Stillwell's paper appeared, the management of the Rosebery and Hercules mines has from time to time submitted a number of interesting mineral specimens to C.S.I.R.O. Mineragraphie Investigations. Examination of these specimens brought to light eight minerals, some relatively uncommon, not previously recognized in these ores.They are cassiterite, molybdenite, stannite, electrum, meneghinite, boulangerite, pyrargyrite and pyrrhotite. Some of the specimens are also rich in tetrahedrite and gold. In addition each of the other ore minerals described by Stillwell, viz. pyrite, sphalerite, galena, bournonite, chaleopyrite and arsenopyrite, was detected in one or more of the specimens examined during the present study. The principal gangue minerals were found to be quartz, manganiferous carbonate, sericite and barite, agreeing closely with the observations of Stillwell.The present study was based on the examination of the following eight specimens.

Jan 1, 1960

By J. E. Allen

The trend in refractory technology for the copper and nickel industries has been to higher quality raw materials and improved processing technology. These changes have been dictated by the changes in pyrometallurgical processes in these industries. For example the introduction of flash smelting, reaction type smelting and auxiliary slag cleaning furnaces havedemanded better refractories materials. Extensive field applications and improved laboratory testing procedures have helped make this transition possible. Changes in refractory technology, primarily in basic refractories, are followed from the late fifties to the present and into the future.

Jan 1, 1994

By I. Nimmo

Since the beginning of Aluminum mining and refining the industry has lived with distributed control rooms and suffered from many behavioral problems common with this design. When Human Factor/Ergonomic design is introduced to a Western Australian installation a common centralized control room realized many improvements including economic payback. Communications issues were resolved, better coordination of materials, improved situation awareness during startups, abnormal operations and an opportunity to make improvements during normal operations characterize the changes at the Worsley Refinery. This presentation will review the reasons for the change. Since the beginning of Aluminum mining and refining the industry has lived with distributed control rooms and suffered from many behavioral problems common with this design. When Human Factor/Ergonomic design is introduced to a Western Australian installation a common centralized control room realized many improvements including economic payback. This presentation will review the reasons for the change, what changed and the process of changing the culture from reactive to predictive and what difference that has made.

Jan 1, 2011

By M. Misra

Acid mine drainage from reactive sulfide tailings is a major environmental concern facing the mining and mineral industries. A preventive technique to control acid mine drainage by agglomeration and encapsulation process is presented in this paper. The reactive tailings are agglomerated using Portland cement type I1 as binder. The cold bonded agglomerates after specified curing period are, strong and resistance to weathering. The leaching and weathering experiments have shown that a significant reduction in the concentration of dissolved metals can be observed with the agglomerates as compared to as- received tailings. Addition of small amount of sodium silicate during agglomeration increases the strength and develop good resistance to weathering by forming a glassy coating and elongated crystals within the agglomerates.

Jan 1, 1993

By Markus A. Reuter, Albert Scholte, Ewoud V. Verhoef, Gerard P. J. Dijkema

A dynamic, interactive map has been developed of the life cycle of a number of metals, from mining through to minerals processing, metal production, product manufacturing, recovery and waste management. Whilst the existing metal process network and waste management infrastructure provide substantial scope for (product) design, these also limit change due to the complex interdependence of metals, both in production and recovery, and the strong path dependency of industry and infrastructure development. Therefore, models for dynamic simulation were constructed that allow the specification and evaluation of the metal process network and waste management infrastructure ‘products’ over a longer time span. The model has been constructed using a bottom-up approach, to enable assessment of the environmental aspects of metallurgy and to simulate changes in the system structure and technology, i.e. from reactor or individual process step up to integrated material cycles. The model comprises hierarchical mass balances and linear models of individual processes and sub-processes. Thus, at lower system aggregate levels an increasing level of technical detail is represented. Data reconciliation has been used literature data on process feed, products and residue composition to calculate representative and reliable split factors around each (sub-)process. World production figures on process capacity and recovery rates are be used to calculate the relative contribution of processes. The dynamic map is illustrated with a case on the introduction of lead-free solder.

Jan 1, 2003

By D. E. Nash

Environmental compliance programs for mining companies are not only important management tools, but can deflect serious civil and criminal penalties if violations of environmental laws do occur. The paper discusses the legal foundation for such programs and their basic structure.

Jan 1, 2001

By Duk-Won Park

A new gage for monitoring fractures in underground openings was successfully developed utilizing the reflection photo-elastic technique. The gage may be used to detect crack initiation in mine openings or tunnels so that remedial action may be taken to prevent further deterioration. Fringes concentrated around the cracks were spread by the use of rubber backing. Crack growth as little as 0.003 inch up to as much as 0.1 inch width were detected in this study. Variation of gage materials will provide alternative ranges. The feasibility of the method was tested and calibration was made in the laboratory study. Field study successfully demonstrated the capability of applications in detecting mine roof crack development.

Jan 1, 1982

By C. Deutsch

Resource estimation for the West Leeville deposit is prepared using a conventional explicit approach. The geologic model is developed using interpretive methods based on visual logging. Grade shells are then prepared at low and high grade cutoffs. The low grade shell includes material of interest (Au > 0.010opt), while the high grade shell is developed slightly below the economic cutoff grade for mining. Grade estimates are made within these boundaries. This paper documents a conditional simulation study to evaluate the uncertainty contributed by both the grade shells and grade estimates. Multiple realizations are generated for the grade shells and the grades. The full combinatorial of realizations are merged to assess the uncertainty and the relative contribution of the grade shell and grades.

Jan 1, 2007

By H. Fujihara, K. Uesugi, H. Toda, A. Takeuchi, K. Shimizu

"Hydrogen is trapped at a variety of microstructures, for example grain boundaries, dislocations and particles. It is thought that hydrogen trapped at trapping sites is redistributed to the other sites under loading and then brittle fracture occurs with hydrogen accumulation. In order to understand hydrogen embrittlement behavior, it is necessary to investigate the time evolution behavior of hydrogen accumulation at each trap site. In the present study, changes in hydrogen distribution are observed under stress using Kelvin force microscopy (KFM) that can visualize hydrogen concentration distribution on material surface at high resolution. Spot-like hydrogen enriched regions are observed on the surface of a material. In addition, hydrogen depleted regions are observed around those enriched regions, and the appearance of hydrogen trap due to particles existing near the material surface is revealed. On the other hand, hydrogen trapped at grain boundary can be visualized. From in this result, it was suggested that crystallographic factors influence hydrogen accumulation. The relationship between initiation and propagation of intergranular crack and hydrogen accumulation under stress will be discussed.INTRODUCTIONHydrogen present in a metal sometimes has significant effects on various properties. Hydrogen in a metal is trapped at a variety of microstructure, for example dislocations and grain boundaries. Grain boundaries, dislocations and micro pores are the major trap sites in aluminum alloys. Some researchers considered that hydrogen redistribution and accumulation between these trap sites in a material with loading plays an important role in the brittle fracture behavior. In general, in intergranular fracture and quasi-cleavage fracture, the hydrogen trapped at grain boundaries and dislocations contributes to fracture behavior, respectively. Recently some researchers have shown that the ductile fracture in aluminum alloys is resulted from growth and coalescence of hydrogen micro pores. Analysis using first principles calculation indicates that intergranular fracture occurs when hydrogen concentration reaches 20 atom H/nm2ongrain boundary. From this report, it is considered that hydrogen redistributed during deformation accumulates locally in order to cause hydrogen brittle fracture. In order to understand hydrogen embrittlement, it is necessary to investigate the time evolution behavior of hydrogen accumulation at each trap site. In the present study, we evaluate the relationship between hydrogen accumulation behavior and fracture behavior in Al-Zn-Mg based alloys. In-situ observation was made by combining the tensile test with Kelvin force microscope (KFM) that can visualize the hydrogen concentration distribution on the material surface with high resolution. We also investigate the relationship between hydrogen distribution behavior and crystal orientation."

Jan 1, 2018

By Peter Moser, Mark Ganster, Radoslava Ivanova, Florian Bauer

Blasting accurately in underground drifts and creating a smooth contour requires proper drilling, knowledge about the apparent geology, a well designed blast pattern and ideally a smooth blasting product. These products are usually cartridged explosives with less energy and are charged in the contour holes in order to reduce the energy concentration and therefore the cracking into the surrounding rock. With the development of a new contour blasting system, a device can now be delivered to the industry that that avoids the additional storage of cartridged products when bulk explosives are used. The system consists of a foldable hose that is charged with bulk emulsion, in the same way as the rest of the blast, from the base to the collar of the hole. It centers automatically in the borehole and provides a decoupled charge. The paper describes the system in detail, gives background information on smooth blasting and presents the first successful field tests using the system in the drifts of an underground mine. It shows the advantages of blast results that produce more stable contours that reduce the amount, time and cost for support but also increase safety underground.

Jan 1, 2012

By S Rice, A Midlin

Many of the stacking and reclaiming machines employed in the mining industry today are operating in ways that were never envisaged in the days before they were commissioned, with greater throughput, increased annualised operating hours and load cycles well in excess of their original specification requirements being the norm. In many cases these machines were supplied prior to the widespread use of finite element modelling or, in the era when such software became commercially available, those supplied designed using simplified and/or coarser meshes than would be employed today. With many of these machines being expected to operate for many years to come, it is important that their ongoing reliability be maintained and their operational limits understood. In this paper, a case study is used to outline the method required for estimating the fatigue life already consumed and the likely real life left in a machine. By reference to the machineÆs prior operating history, the use of strain gauges in the field and the development of finely meshed finite element analysis (FEA), a coherent picture of the machineÆs operational state can be generated and then investment/maintenance decisions made to ensure continuity of machine operation.

Jan 1, 2007

By Michael Hoch, Walter C. Wyder

The isothermul section of the Nb-Ti-Zr-O system at 1500°C was investigated using X-ray dzffraction and metallographic techniques. UP to 66.7 at. pct 0, the system contains nine four-phase regions. Tsopleths at 10, 20, 30, 40, 50, and 55 at. pct 0 weye constructed. The purpose of this investigation was to determine the general shape of the quaternary equilibrium phase diagram of niobium, titanium, zirconium, and oxygen at 1500°C. The system was truncated at 66.7 at. pct. O., PREVIOUS INVESTIGATIONS The Ti-Zr-O system was investigated in this laboratory.' The binary systems of interest have been compiled and discussed by anssen2 and Levin, McMurdie, and Ha11. Elliott4 has determined the Nb-O system by metallographic and X-ray diffraction techniques. He shows the existence of three oxides, namely NbO, NbO2, and Nb2O5. At 1500°C the solubility of oxygen in niobium is about 4 at. pct. No solid solubility region is shown for either NbO or NbO2. EQUIPMENT The same equipment as that for the study of the Ti-Zr-O system was used. The X-ray diffraction patterns were analyzed with the help of the ASTM card set5 and NBS circulars.6 MATERIALS The niobium powder (99 pct pure), the titanium powder (99.6 pct pure), the niobium pentoxide, and the zirconium dioxide used in this study were purchased from the Fairmount Chemical Co., Newark, N.J. The zirconium powder (99.4 pct pure) was obtained from the Charles Hardy Co., Inc., N.Y. Reagent-grade titanium dioxide was purchased from the Matheson Co., Inc., Norwood, Ohio. The oxides were dried in air at 700°C for 24 hr before use. Though the materials used were not "hyper-pure," the impurities present do not affect the results (lattice parameters, phase boundaries), within the experimental accuracy. PROCEDURE Samples of the desired compositions were made up, in mole pct, from the materials listed above. In some cases the intermediate binary compounds, such as NbO and TiZrO4 were prepared beforehand and used in the preparation of the samples. This technique enabled equilibrium to be reached from two sides. The components of each sample were mechanically mixed in a mortar and pestle and pressed into 3/16-in. diam pellets. The pressures used in compacting were of the order of 50 to 100 x 103 psi. Sintering was accomplished by heating the samples in a tungsten crucible (3/4-in. high, %-in. diam, 1/8-in. wall, lid with XB-in. hole). The pellets were separated from each other and from the crucible by means of small spiral coils of tungsten wire placed between the stacked pellets and on the bottom of the crucible. The sintering time was from 4 to 12 hr at 1500°C under a vacuum of 6 x 101-5 to 1 x 10-6 mm of Hg. All samples were reground after the first or second heating repressed, and reheated. In most cases: equilibrium was obtained after the first heating, as the X-ray diffraction pictures after each heating remained unchanged. Quenching of the samples from 1500°C was at first only possible by allowing the crucible and its contents to lose heat by radiation. The temperature dropped from 1500° to 900°c in approximately 1 1/2 min, which was considered adequate when compared to the times used by other investigators to reach equilibrium in the temperature range of 1000°c and lower. Later, a new technique for faster quenching of the samples was cleveloped. This technique involved the removal of the samples from the crucible, whereupon they were quenched by coming in contact with the water-cooled copper base of the furnace. This manipulation was performed without breaking the vacuum. The sample pellets were placed on a tungsten wire rack inside the crucible. The wire rack passed through the hole in the crucible lid, where it was connected to a small nonmagnetic chain. The chain was fed to the side of the furnace by means of a brass rack which fitted between the body and lid of the furnace. Suspended at the end of the chain, near the furnace wall, were three magnetic washers. With the use of a strong

Jan 1, 1962

By Ross W. Whipple

Applying geophysical techniques in potential geothermal areas has received: little attention in the United States, though it is widely used and accepted in New Zealand and Italy. In those countries it has been demonstrated that geophysical surveys can be useful in locating new geothermal areas and in directing test drilling programs. Geophysical studies in a thermal region can provide structural information and, if conditions are right directly; locate subsurface hot waters. They can give indications of sub-alluvial rock types and of the thickness of alluvial cover. In certain cases they can be used to estimate the power potential of a hydrothermal system.

Jan 1, 1963

By Tuan V. Nguyen, Louis Mittoni, Murray Rudman, CSIRO Minerals, Jean D. Swift, John B. Farrow, Phillip D. Fawell

"Research projects towards developing a sound understanding of the factors controlling the performance of gravity thickeners have been conducted by the AJ Parker Cooperative Research Centre for Hydrometallurgy since 1988 through AMIRA International. The current phase of this work, the three year P266D “Improving Thickener Technology” project, has 27 sponsors comprising mineral processing companies, reagent suppliers and thickener manufacturers.These projects have resulted in the development of a range of tools and techniques to address flocculation, thickening and associated dewatering issues. A number of Computational Fluid Dynamics (CFD) models have been developed to predict likely full-scale thickener performance under various process conditions, based upon a knowledge of thickener design, plant flows and assessment of the flocculation behaviour of the feed slurry. At the same time, various laboratory and plant studies have been used to quantify important thickener processes, and to provide validation of the CFD models. These numerical and experimental capabilities have been applied to various thickener issues across a broad range of mineral processing operations, leading to significant process improvements and substantial financial benefits.This paper presents an overview of the work conducted during these projects, focussing on the research tools, the nature of the information that has been gained and the implications for thickener performance."

Jan 1, 2003

By Laurence M. Demers, Douglas C. Kuhn

It has been suggested that radicals on the surface of dust particles are key chemical factors in the pathophysiology which results from the occupational inhalation of coal and silica dust. In addition, oxygenated derivatives of arachidonic acid (eicosanoids) have been implicated as important biochemical mediators of mineral dust-induced lung disease through their role in bronchial and vascular smooth muscle reactivity, inflammation, and fibrosis. Therefore, we assessed eicosanoid production by the rat alveolar macrophage (AM) exposed in vitro to mineral dusts with varying surface chemical characteristics in order to determine if radicals associated with the mineral dub1 could influence the production of pro-inflammatory mediators in the lung environment. Rat AM were exposed to freshly fractured or "stale" bituminous coal dust, as well as untreated silica or silica calcined to 500°C and 1100°C. Prostaglandin E2 (PGE2) and thromboxane B2 (TxB2) levels in incubation medium were determined by specific radioimmunoassay. When AM were exposed to freshly fractured coal dust, PGE2 and TxB2 production were markedly increased. In contrast, exposure of AM to "stale" dust significantly reduced PGE2 and TxB2 production. In vitro exposure of AM to untreated silica resulted in a significant increase in PGE2 and TxB2 production compared to control. However, exposure of AM to silica calcined to 1100°C resulted in eicosanoid levels which were not significantly different from control. These findings suggest that radicals associated with respirable coal and silica particles may play a key role in the ability of mineral dust to activate AM eicosanoid production.

Jan 1, 1991

By H. S. Bell

IT SEEMS unnecessary to dwell upon the advantages of the modern pipe still as compared with the older type of distillation equipment used by oil refiners. The relatively low installation cost, coupled with remarkable operating efficiencies of pipe stills, precludes the consideration of other types except in rare instances where some peculiarity of product or plant may have an influence. The question of the actual heat required to distil petroleum is quite involved. We have extensive data on the latent heats of the various hydrocarbons under different conditions of pressure. We also have information regarding the specific heats of various oils and the effect of temperature thereon. Because of the complexity of petroleum and of each fraction, it seems impossible to theoretically analyze the partial-pressure effect of the great number of hydrocarbons upon one another during distillation. If a distillation curve and percentage analysis of any crude or product are available, it is possible to construct a curve with ordinates representing per cent. distilled and B. t. u. per pound or per gallon, or other desired unit. To do so the crude is split into fractions, of 5 or 10 per cent. The boiling point and gravity of each fraction being determined, it is possible to evaluate the heat required. As each fraction is removed, the residue must be raised to a higher temperature and latent heat supplied for the successive fraction. As the calculations progress, the latent heats decrease while the specific heats increase. Such a curve is illustrated by Fig. 1 for a typical 39.9 B° North Texas crude.

Jan 1, 1928

By Tony B. Szwilski, K. Unrug

INTRODUCTION Since the introduction of longwall coal mining systems, reliable predictions of roof support requirements at the face and the roof caveability in the gob area have been major contributors to the success of the longwall face by means of safety and face productivity. That is, the successful operation of a longwall is well-served by good regular caving of the gob. In recent times, with the advent of increased coal face mechanization and capital investment, the evaluation of the feasibility of longwall mining has become essential. In the United States, where a face unit for a face length of about 150 metres may cost around $6 million, a quantitative system that would assist in selecting the best equipment for the coal would prove extremely beneficial. There have been many such varied investigations in the past few years. A vast -amount of work has been invested principally by West Germany [3, 7, 8, 91 , Poland [I, 101 , United Kingdom [4, 5, lo], France [4], and South Africa [4]. It is the object of this paper to review this previous research work and give an outline that may be used as guidelines for long- wall evaluation. Essentially, for the initial design phase for a longwall system, account must be taken of the geometry of the coal panel, its position relative to the surface (depth), direction of the coal cleat system, faults and in-situ stresses and other neighboring workings in the same coal seam and other seams both above and below. The advance of the coal panel disturbs the stress field and in doing so creates an abutment zone around the face. At this stage the condition of homogeneity of the surrounding rock mass does not apply. The magnitude of the rock strata pressure may exceed the ultimate strength of the rocks and create zones of clastic, plastic and elastic material, the limits of which are difficult to determine. The collapse of the gob and resulting expansion of the displaced waste roof rock, create a statically undefined support complicating an already unclear rock structure. For example, it is often a point of debate whether, indeed, the vertical strata pressure develops to regain the original magnitude of virgin stress. Under these post-failure circumstances an analytical approach based on simplified and idealized assumptions can only be considered a very general approximation. Theoretical concepts, however, may be adequately supplemented by empirical methods that are based on numerous underground observations and surveys [3, 4, 7, 8]. These methods employ the use of rock indices that very handily correspond to the competence of the roof rock mass. Scale model work [3, 41 , using equivalent materials representing the surrounding rock mass within the coal seam zone, have given valuable qualitative and sometimes quantitative data in addressing the behaviour of the rock mass around longwall panels. To characterize the state of art of caveability predictioqthe principal concepts will be reviewed with special emphasis placed on practicality for the planning of longwall operation. It has been the general observation of the authors that many of the literature surveys published in English often neglect reference to other international mining literature. It is with this point in mind that an overall review has been written including mining concepts identified with the principal coal mining countries. THEORETICAL CONCEPTS Arching Theory For the development of this theory, assumption has been made that an extracted height, h, in a coal seam results in an extracted panel of width, w . Also, the coal seam is horizontal and the rock strata of both the roof and floor are homogeneous. The primary (virgin) stress distribution will change in the roof as well as the floor. As a result of lack of support caused by the excavation (in the gob area) an additional load is developed due to the redistribution of the load around the sides of the panel, referred to as the abutment, R, where: [ ]

Jan 1, 1982

By Maria Salazar-Villalpando, Todd H. Gardner

"Efficient utilization of CO2 can help to decrease global warming. Methane reforming using carbon dioxide has been of interest for many years, but recently that interest has experienced a rapid increase for both environmental and commercial reasons. The use of CO2 provides a source of clean oxygen, which eliminates the need for costly oxygen separation plants. The product of dry reforming is useful syn-gas, which can be used to generate electrical power in a SOFC or in the production of synthetic fuels (hydrocarbons and alcohols). Hexaaluminate catalysts prepared at NETL may represent a product that can be utilized for the conversion of CO2 to syn-gas. In this work, transition metals dispersed in barium hexaaluminate have shown to be promising new catalysts for dry methane reforming. In this investigation, a series of BaNixAl12-yO19-d catalysts with varying Ni content were prepared by co-precipitation followed by calcination at 1400°C. CO2 reduction by dry methane reforming was carried out to determine catalyst performance as a function of temperature and carbon formation was also quantified after the reforming tests. Results of catalysts characterization, dispersion and surface area, were correlated to catalytic performance.IntroductionEfficient utilization of CO2 can help to decrease global warming. Methane reforming using carbon dioxide has been of interest for many years, but recently that interest has experienced a rapid increase for both environmental and commercial reasons. The use of CO2 provides a source of clean oxygen, which eliminates the need for costly oxygen separation plants. The product of dry reforming is useful syn-gas, which can be used to generate electrical power in a SOFC or in the production of synthetic fuels (hydrocarbons and alcohols). The dry reforming reaction has been known for a long time. Recent publications have reported studies over several catalysts. For example, the CO2 reforming of CH4 over mesoporous nanocrystalline zirconium powders (ZrO2–3%M2Ox; M: Ce, La and K) at 700ºC have shown methane conversion up to 60% (1). Similarly, the effect of Ni content (1–12 wt%) on the surface and catalytic behavior of bimetallic PtNi catalysts supported on ZSM-5 for reforming of methane with CO2 has been studied and report shows a maximum conversion of 16% and catalyst deactivation was observed during the first hour of time on stream (2). In another report, (3) Ni/a-Al2O3 catalyst was tested for syn-gas generation at 750ºC. The maximum methane conversion was 25%."

Jan 1, 2008

By J. D. Morgan

Demand for nonfuel minerals depends on the overall state of the economy, which steadily improved each quarter in 1984. New housing starts rose to 1.8 million units. Automakers turned out about 15% more cars (7.8 million) and 30% more trucks (3.1 million) than in 1983. Nevertheless, many domestic mineral operations experienced difficulties in 1984. This resulted from import competition greater use of newer engineered materials, emphasis on multi-unit housing and downsizing of motor vehicles. About 15% of our energy was imported. This in cluded $36 billion worth of crude oil and $22 billion in refined products This added significantly to the overall merchandise trade deficit of $12; billion. On the bright side for mining, coal production rose 14% to 810 Mt (890 mil lion st). Three-fourths o: the coal was burned to generate electricity and more than half of our electricity was derived from coal-burning plants. With the exception of a few large-bulk, low-value raw minerals, most minerals move relatively freely in world trade. The strong dollar encouraged imports and made exporting more difficult. Consequently, our nonfuel minerals trade deficit rose 60% to $19 billion, reflecting imports of $39 billion and exports of $20 billion. There were increased pressures from some major segments of the minerals industry for some form of import protection. But President Reagan said, "Our goal is a system of free and fair trade in goods, services, and capital. We will work toward this goal through both bilateral and multilateral trading agreements." The US minerals industry consists of domestic mines, concentrators, smelters, refineries, mineral manufacturing plants, and recyclers. It also includes many wholly- or partially-owned operations in many parts of the world, providing employment and income for US citizens and others as well. Compared with 1983, the value of US raw nonfuel mineral output rose 8%, to $23 billion. The $253 billion worth of goods processed from this crude mineral output was a 14% increase. Major Metals Raw steel production - a major indicator of both material use and mineral production-rose 10%, to 84 Mt (93 million st). This stimulated a 36% rise in domestic iron ore production, to 52 Mt (57 million st), about 98% pelletized. Iron ore imports rose 44%, to 14 Mt (15 million st). Despite the increase of steel production, output remained well below levels of just a few years ago. For example, 1984 production was still 23% less than in 1981. Raw steelmaking capacity remained steady at 122 Mt (135 million st). The industry continued to cite steel imports as a major reason for low domestic capacity. In December, pacts with seven leading steel exporting nations were announced. This is an effort to reduce import penetration to about 18.5% of the domestic market. Domestic producers of bulk ferroalloys of chromium, manganese, and silicon operated at about 50% capacity. The US mined no manganese or chromium. Only a small quantity of ferronickel was produced from domestic laterite mining in Oregon. Molybdenum production, at 45 kt (49,500 st), rose threefold. Mine shipments of tungsten, another mineral tied to steel

Jan 5, 1985

By Schoeman L., K. C. Sole

Evaluation and measurement of the influence of changes in conditions and electrolyte composition during early stages of a growing metal electrodeposit are crucial to predict changes in developing morphology. A galvanodynamic polarization technique was developed to reliably measure overpotentials for nickel electrodeposition from sulfate electrolyte. The validity of these polarization parameters as indicators of the relationships between changes in the electrolyte and resulting deposit morphology was evaluated for electrolytes of varying composition. Findings indicate that nucleation and plating overpotentials measured by the described technique can be used as indicative tools for monitoring, evaluating and ultimately improving control of the electrodeposition of nickel from sulfate electrolytes. The results predict that nickel deposits of desirable quality and morphology are obtained when plating overpotentials are higher than 700 mV vs. Ag/AgCl and nucleation overpotential is less negative than plating overpotential.

Jan 1, 2017