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By D. Denton, M. Stickney, R. Langston

The National Institute for Occupational Safety and Health and the Stillwater Mining Company worked cooperatively with the Montana Bureau of Mines and Geology to develop a system that would collect seismic data at the Stillwater and East Boulder mines. The purpose was to obtain baseline information on the magnitude and location of mining-induced seismicity to determine if the mines needed multi-channel in-mine monitoring systems. Seismic data recorded at field sites near the mines are being telemetered via FM radio through a series of repeaters to a central recording site where the seismic signals are digitized using an Earthworm data acquisition system. The Earthworm system performs several data analysis tasks in near-real time and places raw seismic data, preliminary hypocenter locations, and magnitudes on a Website within 5 min of a seismic event. Such rapid access to seismic data allows personnel at the Stillwater Mine, Spokane Research Laboratory, and Earthquake Studies Office to evaluate seismic events quickly and respond in ways that may improve the safety of mine personnel underground. Installation of the system also broadened earthquake coverage to south-central Montana, a region previously not covered by the seismograph network.

By M. Abdellatif

"SynopsisCalcined basic nickel carbonate (BNC) concentrate was smelted in a pilotscale DC arc furnace to produce a nickel metal. The furnace was continuously operated for 12 days (24 hour/day), during which twelve different smelting conditions were investigated, with the major variables being reductant type and feed rate, flux composition and addition, and BNC feed rate.The 200 kW DC arc furnace was operated at power levels between 110 and 165 kW and at a total feed rate of 78 to 96 kg/h, resulting in an average slag and metal tapping temperature of about 1650°C. A total of 7.2 t of BNC were smelted, producing about 5.44 t of nickel metal and 2.94 t of slag. Nickel recoveries of 96.4% and higher were achieved, and the slag nickel content was as low as 0.1%. The major impurities in the metal were iron (mostly from oxygen lancing) and carbon. The calculated feed carry-over was less than 0.85% and the graphite electrode consumption was between 2.8–3.3 kg/MWh.IntroductionOne of the most distinctive advantages of DC open-arc smelting is the ability to process fine raw materials without any major issues with regard to the operability of the furnace, metal recovery, and metal quality. This has been demonstrated in Mintek’s DC arc pilot plant facilities over a period of about three decades (Curr et al., 1983). The materials that have been processed include laterite (Kotze, 2002), chromite fines (Curr et al., 1983), manganese fines (Lagendijk et al., 2010), PGM concentrates (Shaw et al., 2013), electric arc furnace (EAF) dust (Denton et al., 2005; Abdellatif, 2002a) and stainless steel (SS) dust (Denton et al., 2005; Abdellatif, 2002a; Goff and Denton, 2004), and petroleum fly ash (Abdellatif, 2002b). The top particle size of such materials can vary from a few millimetres (e.g. laterite) to micrometres (EAF and SS dust). Dusting, whether due to physical carryover of feed or to the arc side reactions, has been proven to be a non-issue. As such, the applications of DC open-arc furnaces have the potential to be extended to other raw materials such as particulate nickel oxide, which has a particle size much less than 100 µm.Nickel oxide is typically produced from laterite ore by sulphuric acid leaching, purification, and precipitation as basic nickel carbonate (BNC) (Rhamdhani, Jak, and Hayes, 2008) or as mixed hydroxide precipitate (MHP) (Mackenzie, Virnig, and Feather, 2006), and finally calcining at moderate temperatures (800–1200°C). The NiO product is very fine, with an average particle size in the range of 10–20 µm and a NiO content of more than 99%."

Jan 1, 2015

By J. W. MacDonald

Two coal mine shafts recently completed in Franklin County, Ill., afford experience and accomplishment to warrant review, These shafts provide access to a tract with a potential recovery of one hundred million tons. This work provided the initial sinking by other than a contractor's organization since 1918. Four additional shafts required during the interim were sunk under contract arrangement with others. Supervisory contact and inspection afforded experience to govern planning and conduct of the recent work.

Jan 1, 1960

By L. Sandbak

The Turquoise Ridge Joint Venture (TRJV) is located in northern central Nevada, and is situated within the Basin and Range province, near the northeast end of the Osgood Mountains (see Figure 1). The TRJV mine consists of typical Carlin type- gold mineralization characterized by low strength rock of altered limestones, siltstones, and mudstones. The weak nature of the ground facilitates the underhand cut and fill mining methods. TRJV has been working to optimize ground support and mechanize top cut drift sizes and eliminate operating hazards associated with jackleg drilling. Safety Factor analysis based on bolt strengths has allowed us to pursue larger sized top cut drifts and to evaluate bolt length sizes and spacing. Switching from jackleg sized drifts of 10?W x 10?H to a mechanized 12?H x12?W top cut drift design has the potential to decrease overbreak, provide more uniform drift design sizes and bolt patterns, and increase ore production by at least 38%.

Feb 23, 2014

By John Nagy, Hylton R. Brown, Irving Hartman

"INTRODUCTION The tests described in this publication were planned to provide information on the explosibility of metal-powder dust clouds. This subject has become increasingly important because of the large quantity and variety of metallic powders now used for military and industrial purposes. To provide the increased amounts of metallic powders needed in the manufacture of munitions and to supply the demand created by the rapid growth of powder metallurgy, existing metal-powder plants have been enlarged, production schedules accelerated, and new plants erected. In some cases new methods of producing metal powders have been developed. This increased production and the development of new manufacturing methods have caused an increase in the number of metal-powder fires and explosions, with accompanying heavy loss of life and property. These have emphasized the need for information on methods of providing protection against hazards inherent in the production and handling of powdered metals. This paper gives results of laboratory inflammability and explosibility tests made to April 1, 1943, and is a progress report. Many descriptive details have been omitted purposely; they will supplied in a later publication, expected to be a Bureau of Mines bulletin."

Oct 1, 1943

By David Dvorkin, Thomas C. Anderson

INTRODUCTION A major function of the Mine Safety and Health Administration (MSHA), Denver Safety and Health Technology Center (DSHTC), Ventilation Branch, is to provide engineering analyses of underground mine¬ ventilation systems for coal, metal, and nonmetal in¬spection departments in accordance with field surveys and data analyses. Health and safety problems such as the control of diesel contaminants, dust, methane, radon, and radon daughters all are dependent upon ventilation. It is necessary for the ventilation engineers at DSHTC to have a complete understanding of the various and highly complex ventilation systems used in the nation's mines. Only through the proper assembly and analysis of data can the engineer determine the causes of prob¬lems and make suitable recommendations. Furthermore, the engineer must have the ability to predict the results of any such recommendations. In the study of the ventilation system at any indi¬vidual mine, it is common practice to collect data on airflow quantities and pressures at key points throughout the mine. However, these data give only a single point¬-in-time view of the system. As the mine develops and progresses, the system undergoes numerous changes; as the mine becomes more extensive, the ventilation re¬quirements increase, and the costs rise. For proper utilization of the available resources, it is necessary for the engineer to have a sound engineering basis for deci¬sions on how best to ventilate the mine. To evaluate the system as a whole, particularly re¬garding possible system changes, it has become necessary to rely on computers to perform the calculations in¬volved in analyzing the network. This chapter sum¬marizes the implementation of such computer capabili¬ties at DSHTC, as well as the services that are available from DSHTC. ANALOG SIMULATIONS AND ANALYSES OF VENTILATION NETWORKS As early as 1954, the US Bureau of Mines (USBM) in Pittsburgh, PA, was using an analog computer as an aid in analyzing ventilation systems. The Mcllroy Fluid Network Analyzer used filament-tube resistance elements and an electrical power supply to simulate mine-ventila¬tion systems electrically. This system is shown in Fig. 1. Analog simulation has proven to be a practical tool, providing fast analyses of complicated problems after the initial setup has been completed. Advancements in electronic technology over the past 24 years have made possible the construction of an analog computer that has streamlined several operating features of the previous machines. The DSHTC Ventilation Branch now has an improved electronic analog computer to assist in the analyses of ventilation systems. General Features As shown in Fig. 2, the analog computer used at the DSHTC Ventilation Branch has three "element" cabi¬ nets, a console, and a printer. The cabinets contain the fan elements and the airway-resistance elements that are used to "program" an analysis problem; each element is independent of the others. The console contains the "patchboard" and the controls necessary to operate the analog computer. The patchboard connects the inde¬pendent elements into the circuit appropriate for simu¬lating the ventilation system. The total system is controlled from a panel on the console, while the value corresponding to each element is set on the individual controls located on the face of each element. The control panel has three visual output displays that give the quantity of flow, the pressure of the output junction with respect to a datum, and the differential pressure across each element. The control panel also allows manual selection of the element to be monitored, or automatic scanning and printing of values for the entire system. Capabilities The analog computer can simulate an existing mine¬-ventilation network. This is accomplished by collecting field data at the mine to give a complete pressure-¬quantity network. Resistance values for each airway branch may be determined from the quantity of flow in the branch and from the pressure differential between the end-point junctions of the branch. The basic rela¬tonship to determine the resistance is expressed as: H=R •Q2 where H is the pressure differential, R is the resistance, and Q is the quantity of air in the flow. After the resistance values are known for all of the airways in the circuit, the elements on the analog com¬puter can be set to the corresponding values. The elements are designed to reflect the basic relationships, with electrical potentials corresponding to pressures and

Jan 1, 1982

By R. Schuhmann

Available thermodynamic data applicable to copper smelting systems are collected and tabulated, and the important gaps are pointed out. A few examples are given of estimations which can be made from the available data. An experimental research program is proposed to supply the thermodynamic data that appear most essential to better quantitative understanding of the chemistry of copper smelting. The proposed program is designed also to shed specific light on the practical problems of slag losses and magnetite behavior. OPPER smelting, from flotation concentrates to V-/ blister copper, is conspicuous among the large scale chemical processes which are conducted with only relatively incomplete knowledge of the physical chemistry involved. For example, no common metallurgy text explains adequately why copper enters the matte phase while iron enters only to the extent that sulphur is left over after satisfying the copper. Explaining this important phenomenon as a manifestation of the greater affinity of sulphur for copper than for iron is unsound because the affinities of copper and iron for sulphur are about the same at smelting temperatures. As will be shown, other affinities are really decisive in the relatively clear-cut separation of copper in the matte. In contrast, thermodynamic studies have contributed much to our understanding of copper refining, zinc oxide reduction, magnesium production, steelmaking, etc. For each of these processes, the important reactions are clearly recognized, and fair to good quantitative values of the free-energy changes and equilibrium constants are available. Such data have proved to be of constantly increasing practical value in process development and improvement. Work in other fields has furnished much thermodynamic data applicable to copper smelting systems. In fact, several promising starts have been made in applying such data to specific smelting problems. Kelleyl made an appraisal of the possibilities of recovering elementary sulphur from low grade matte. His calculations and compilations of thermodynamic data have represented the starting point for much of the work in this field, including the present survey. Huang and Hayward2 nd Aksoy3 used thermodynamic methods in the study of copper losses in reverberatory slags. Peretti4 used thermodynamic data in explaining the chemistry of converting. The recent publications of Darken and Gurry"." and of Darken,' dealing with the iron-oxygen and iron-silicon-oxygen systems, respectively, present equilibrium data that are applicable to copper smelting systems. Also additional data were reported recently on the affinity of sulphur for copper, manganese, and iron8 and on the sulphur pressures of iron-sulphur melts." The survey presented in this paper was made as the basis for planning an experimental program on the thermodynamics of copper smelting. Few researches on the chemistry of copper smelting have been reported in recent years, so that a reappraisal and coordination of old and new data are essential if further work is to take the directions of maximum value. The experimental program is now in progress, and the plan of attack is outlined at the end of this paper. Progressive Oxidation and Desulphurization of Copper-bearing Liquid Phases: The chemical activities of sulphur and oxygen are two of the most important thermodynamic yardsticks to be applied to copper smelting processes. Virtually the entire smelting and refining sequence involves a series of systems characterized by decreasing sulphur activity and increasing oxygen activity. In this section, therefore, an attempt is made to define and explain these activities in terms of equilibrium partial pressures of SO2, s2, and O,. Also, estimates of these quantities are presented, the estimates being based largely on calculations presented in a later section of this paper. The sequence of steps from raw flotation concentrate to fully oxidized copper ready for poling involves progressive and controlled oxidation. Iron is oxidized and enters the slag. Sulphur is oxidized and leaves in the gas. Table I summarizes several important features of this oxidation and desulphurization sequence, starting at the beginning of the matte blow in the converter. The top line gives in order the principal smelting and refining stages up to fully oxidized copper, plus the additional step, not used commercially, of oxidizing all the way to Cu,O. In the second line are shown the principal copper-bearing liquid phases which characterize the process. Through most of the sequence the copper

Jan 1, 1951

By Meghan M. Murphy, Derek Penrice

The Downtown Rail Extension (DTX) is principal element of the planned second phase of the Transbay Joint Powers Authority’s (TJPA) Transbay Program. When complete, this regionally critical project will connect Caltrain’s regional rail system and the California High-Speed Rail Authority’s statewide system to the Salesforce Transit Center in downtown San Francisco via a 1.3-mile tunnel. Studied since the 1970s, the DTX has now received environmental clearance, and key stakeholders are aligned on the project’s configuration and its expedited delivery. This paper describes efforts to optimize the DTX configuration and develop an informed project delivery strategy that incorporates construction industry feedback on project phasing, contract packaging, and procurement methods that accomplish the project’s budget goals.

Jun 13, 2021

By I. R. Muirhead

"One approach to making new technology available is to demonstrate its value under full-scale operating conditions. Studies were undertaken to assess the feasibility of this approach to introducing a longwall mining system to the western Canadian coalfields.The longwall method of mining coal is described, world and Canadian usage is reviewed, and the merits of the system in comparison 10 other coal mining methods are discussed.The rationale for a longwall demonstration in western Canada is presented, along with a proposed organization for the design, operation and dissemination of the findings from such a trial. The factors which must be considered in the design of the demonstration, and in the assessment of a potential site are highlighted. It is concluded that a demonstration of this technology is both timely and essential to prepare the way for the western Canadian coal industry of future prospects for coal.IntroductionFor many years CANMET has encouraged research work organized on a cooperative basis. This requires that a working consensus must be negotiated by researchers and operators at the beginning of the project and continuously refined as work proceeds. The result is usually a more relevant selection of research problems, improved direct ion and con duct of experiment al work and often a validation phase in which research concepts are tested in an opera ting environment. All this tends to narrow the gap between obtaining research results and applying them.Even under the best of circumstances cooperative projects require a good deal of coordination and enthusiasm to maintain focus and the pace of work. The working perspective of a research scientist in a government laboratory is substantially different from that of a mine operator at a producing mine, and a common ground must be found. This is difficult to do and cooperative projects typically evolve over several years as experimental results progressively define the potential solutions to mining problems."

Jan 1, 1985

By Bruce D. Hanson

The Bureau of Mines conducted a series of experiments using four different coal types to determine the effect of attack angle and symmetric bit wear on airborne respirable dust (ARD) generated by point-attack bits and in energy consumption. Neither had a significant effect on ARD at the 95-pct confidence level, but bit wear had a significant effect (95 pct confidence) on specific energy (energy per gram of cut coal) for three coal types, Depth of cut was the most significant factor affecting ARD and specific energy.

Jan 1, 1979

By L. W. Holm, A. K. Csaszar

A series of laboratory experiments was conducted in which oil was displaced from a porous medium by water-driven slugs of alcohols or similar solvents. The solvents used were soluble to some degree in both oil and water and covered the range of solubilities from complete solubility in oil to complete solubility in water. Displacement experiments were conducted on 2-and 3%-in. in diameter consolidated cores and 1-and 2-in. in diameter unconsolidated sand packs. The cores and sand packs ranged in length from 1 to 30 ft, and they were saturated with brine and crude or refined oils. The solvents used included ethyl alcohol, isopropyl alcohol (IPA), tertiary butyl alcohol (TBAI, secondary butyl alcohol (SBA), n-amyl alcohol (NAA), methyl ethyl ketone, acetone and others. It was found that all of the oil present in a porous medium could be miscibly displaced by injecting a slug of mutual solvent and driving it with water. The oil-recovery efficiency was dependent upon (1) the relative solubilities of the solvent in oil and water, and (2) the distance traversed by the flood. For complete oil recovery from cores, a smaller amount of a preferentially oil-soluble solvent was required, compared to the amount of preferentially water-soluble solvent needed. The size of the solvent slug required varied inversely with the linear flooding-path length raised to the 0.65 power. Water-driven dual solvent combinations (an oil-soluble solvent slug followed by a water-soluble solvent slug) were found to effect complete oil recovery with less total solvent than any single solvent used. In these dual-solvent displacement experiments, the slug size required varied inversely with length raised to the 0.55 power. Based upon the experimental results, a theory was developed to describe the displacement of oil and water by mutual solvents, and equations are presented to predict the production history in a linear system. These equations take into account the properties of the solvents and the porous medium. INTRODUCTION Oil-recovery processes which utilize displacing fluids that are miscible with the reservoir fluids have been studied extensively in recent years. Because of the poor contact efficiency and high pressure requirements of the LPG-gas displacement process there has been considerable interest in the alcohol-water process, and a number of studies have been made on the recovery of oil through the use of solvents which are mutually soluble in oil and water. An investigation by Sievert, Dew and Conleyl indicated that the use of mutual solvents would be limited because the presence of water in a porous medium would cause a phase break in the leading edge of the displacing solvent. Their study also showed that, in consolidated cores containing. only oil, the displacement of oil by a water-driven mutual-solvent slug of tertiary butyl alcohol (TBA) was affected by the viscosity ratios of the fluids involved. Gatlin and slobod3 concluded that an isopropyl alcohol (IPA) slug acts as a miscible piston, completely displacing both oil and water until the alcohol content of the mixing zone falls below the concentration necessary to maintain miscibility. Their study was conducted on uniform unconsolidated sand packs. They concluded further that IPA could be used effectively to recover oil from a watered-out sand. In a paper by Taber, Gamath and Reed4 relating an investigation on sandstone cores, it was stated that the displacement of oil by mutual solvents, particularly IPA, was not a miscible displacement and that no improvement in efficiency could be expected with increase in flooding-path length. However, their analytical analysis of the displacement mechanism using TBA is, in fact, one which indicates that the displacement is controlled by miscible mixing. They suggested that the lack of improvement in efficiency with flooding - path

Geophysics is playing an increasingly important role in the exploration industry. In the soft rock scene the application of seismic techniques is basically mandatory prior to any drilling program. Simply, this is because, in a majority of situations, the seismic method is ideally suited to mapping accurately relatively flat lying strata and displaying structures that may host oil or gas. It is worth stressing that seismic methods do not delineate oil or gas but they map well in two or three dimensions. In the base metal arena, geophysical methods used are generally focussed on direct detection methods with the mapping application not often used except in potential fields (magnetics and gravity). The success rate in the last decade has not been good but this does not only apply to the application of geophysics; it really applies across the board of exploration techniques. Both geological and geochemical exploration have not had a success rate commensurate with the funds injected. Basically in the last ten years we have failed as explorers! As explorers we have been negligent in mapping. As geoscientists we have let the basic mapping and observation skills diminish û the old adage æboots on the groundÆ is still applicable but are we doing enough of it? The answer is clearly no. As explorers the huge burden of bureaucracy, eg Government Acts û local, state and federal, safety compliance, environmental compliance, etc has reduced the ægeologicalÆ time dramatically. This has culminated in an over-reliance on quick fix solutions, eg spot the bump geophysics or geochemistry. This obviously simplistic scenario is arguable but there is no doubt in the geoscientific areas we have failed in the last decade to provide adequate geoscientific maps to assist in exploration. This failure could partially be responsible for the current demise of the industry resulting in a reduction in exploration dollars and, hence, people. This trend is seen acutely in the geophysical area where the head count in comparison with the geological fraternity is low. Other trends during this downturn are inevitable as explorers maximise the use of the dollar in exploration and diminish spending on advances in geophysics. Improvements are being seen however in geophysical equipment, although it is considered that the main improvement will be in the interpretation of data. Specifically, the trend will be towards integrating geophysical data into geological, geochemical and spatial data sets producing quality interpretation and providing low risk drill targets. Examples of the current trends in hardware and future directions are discussed below. In interpretive schemes there are very few examples of integrated interpretation but the possible trends will be discussed with limited examples.

Jan 1, 2000

By J. M. Pachter

Property sales and acquisition are prominent features of today's coal industry. Before selling or buying a site, a company must know the property's economic net worth. Any evaluation of economic net worth would be inadequate if determinations of a property's environmental liabilities and costs were omitted. Short-term and long-term costs can result from liabilities related to reclamation, water treatment, subsidence, and hazardous waste disposal. A structured, interdisciplinary approach can aid in the delineation, summation, and scheduling of these costs and liabilities.

Jan 1, 1986

By José Francisco Carbajal, Juan Carlos Alcas

En Piura, el bosque seco tropical desaparece a un ritmo de 20 mil hectáreas anuales. En respuesta a esta situación, Compañía Minera Miski Mayo desarrolla, desde septiembre de 2012, el “Proyecto de forestación y manejo forestal comunitario de las áreas de la mina de fosfatos Bayóvar”, en el que participan activamente los pobladores del área de influencia, asociaciones de ganaderos y otros actores locales. Este proyecto plantea una intervención integral que permite la forestación y el manejo sostenible de extensiones de bosque seco despoblado, bajo un enfoque que asegura el equilibrio ambiental y el equilibrio económico a través de la generación de cadenas productivas, tanto como la mejora de la calidad de vida mediante la contratación de mano de obra local y el aprovechamiento de los nuevos recursos.

Jul 30, 2019

By Isaias Moreira de Freitas

Componentes de alto custo como rodas ferroviárias estão em pleno desenvolvimento a fim de aumentar o desempenho em operação. Para isso, diversos materiais microligados têm sido testados para obter melhores propriedades mecânicas e metalúrgicas. Esses materiais estão fortemente sujeitos a fraturas devido às solicitações térmicas e mecânicas durante o trabalho. Muitas dessas fraturas frágeis são ocasionadas por propagação de trinca, impacto, fadiga ou alguma falha metalúrgica. Essas fraturas e riscos operacionais vêm aumentando gradativamente com as maiores cargas transportadas. Portanto, novos materiais e processos produtivos devem ser exaustivamente testados a fim de garantir alto desempenho e confiabilidade. O objetivo deste trabalho é avaliar as propriedades dos materiais atuais e de diferentes composições de aços microligados de rodas ferroviárias de vagões, fabricadas pelos processos de fundição e forjamento. As amostras foram submetidas a ensaios metalográficos, mecânicos e de tenacidade à fratura. Foram avaliadas rodas convencionais, microligadas ao vanádio e microligadas ao nióbio. Nas rodas forjada e fundida, foram observadas propriedades de tração e dureza similares, e superioridade para o microligado em relação ao aço convencional. As rodas forjadas apresentaram melhor resistência ao impacto e a tenacidade a fratura, destacando-se a microligada ao nióbio.

Aug 16, 2017

By Rafael Henrique Alves Gomes

A automação em processos industriais agrega qualidade, padronização e segurança aos produtos e pessoas envolvidas. Entretanto, as demandas de mercado, custos agregados e a concorrência exigem melhorias que podem ser alcançadas através de métodos de otimização. Este artigo apresenta algumas metodologias e ferramentas para otimização de processos industriais que visam desvincular a obrigatoriedade de que Técnicas de Controle Avançado em métodos de otimização são a única solução capaz de oferecer resultados satisfatórios para aumento de produtividade. Os recursos expostos abordam a gestão de malhas de controle, gestão de alarmes e o cálculo do indicador global de eficiência, o OEE.

Aug 17, 2017

By Marcos Pereira Manso, Carlos Alberto Rodrigues Lares, Sandro Luiz Zahner, Alexandre Dolabella Resende, Marcelo Martins Ferreira, Rodrigo Garcia Ribeiro

O Distribuidor é um equipamento fundamental no processo de Lingotamento Contínuo por ter como função, dentre outras, assegurar a continuidade do processo durante a troca de panela, bem como manter o aço líquido na temperatura adequada para o processo. O presente trabalho apresenta um estudo de melhoria no Distribuidor da Gerdau Divinópolis, no qual foi realizada a redução da temperatura de entrada do aço no distribuidor após modificações no projeto refratário e estudos de simulação numérica. As simulações indicaram que seria possível uma redução significativa da temperatura de entrada do aço no distribuidor e a implementação na prática dessa alteração levou a ganhos significativos, tais como, redução de Power On, redução de Temperatura Média para liberação e consequente redução de consumo de energia.

Oct 1, 2019

By F. R. Archibald, F. C. Jackson

The. prospect of winning aluvinum from clay was recorded almost a century ago at a time when the metal was no more than a curiosity.$ As the industry developed, and it has probably developed faster than that of any other metal, the expanding need for raw materials was adequately met by the ample supplies of bauxite ore. As with the other metals older in industry, however, lower grade ores have gradually entered the raw-material field through improvements in ore dressing, insufficienoy of high-grade ore supplies, favorable geographic location, or national necessity for domestic supply. So with aluminum, or alumina, which has been established as the requisite intermediate, the time may have come when a satisfactory process, with favorable location and suitable raw materials, can hold a sound place both in metallurgy and economics. It is the purpose of this paper to describe the Ancor process and its proposed application in treatment of clay in a plant now under construction at Harleyville, South Carolina, by the Defense Plant Corporation. Development of the AncoR Process The Ancor process has developed through successive stages of laboratory investigation, pilot-plant demonstration using neph-eline syenite and pilot-plant demonstration using kaolin-type clay from South Carolina, and is now in preparation for unit trial on an operating plant basis using the latter material. The laboratory studies were carried out over a number of years in the laboratory of the American Nepheline Corporation in Rochester, N. Y., and for the same company in the ore-dressing laboratory of Beattie Gold Mines, Que. Ltd. at Dupar-quet, Quebec. Both companies are associated with Ventures Ltd., Toronto, and its associated American companies. The work was originally undertaken with a view to recovery of alumina and alkalies from nepheline syenite as an adjunct to the American Nepheline Company's established business in the glass and ceramic trades, but as a process developed the possibility of application to clay and other aluminous raw materials became apparent and the laboratory studies were broadened to include these as well. Under the more pressing impetus of wartime needs and possibilities, pilot-plant operations were undertaken at the Canadian Bureau of Mines Ore Dressing Laboratories in Ottawa, and for purposes of demonstration under joint sponsorship of the Canadian Bureau of Mines, The American Nepheline Corporation, and The Aluminium company of canada Ltd. Upon completion of this program, of

Jan 1, 1944

By G. Sachs, L. J. Ebert, W. F. Brown

INTRODUCTION ISOTHERMAL transformation, or "austempering," of a carbon-containing austenite at elevated temperatures yields so-called "intermediate products." Their structure and properties are, for a given hardness, rather different from those of "tempered martensite" obtained on conventional quenching and tempering.1 Several investigators2,3 have found that for high carbon and slightly alloyed steels the intermediate products formed at temperatures close to that of the martensite reaction possess strength properties superior to those of tempered martensite. The structure of these low temperature, intermediate products is generally acicular (bainite) but clearly different from that of martensite. However, at higher austempering temperatures, between 1000 and 1300°F (540 and 700°C) carbon steels were found to exhibit a rather low ductility.4-5 Thus notch bar tensile tests showed the ratio between notch strength and regular tensile strength to decrease with increasing austempering temperature. For ductilities below a few percent this notch strength ratio is a measure of ductility, according to investigations on low alloy steels.6-7 Furthermore the presence of intermediate products formed unintentionally on quenching was considered as responsible for the low ductility and impact energy of some heat treated steels.8 These intermediate products could result from partial transformation at the so-called "nose-temperature" where the rate of the transformation is a maximum. Tempering improved such mixtures of martensite and intermediate products, their properties approaching those of tempered martensite of equal hardness. The following investigation constitutes an attempt to determine certain strength properties of a partially austempered and subsequently quenched low alloy steel, namely, a chromium steel (SAE 5140). The structures formed by such a treatment should consist of a mixture of intermediate products formed on austempering and a martensite formed on oil quenching from the austempering temperature. It was intended, by varying the austempering time, to vary the quantity of the intermediate products between zero and 100 pct. The austempering temperature of 860°F was selected after extensive preliminary tests close to the nose-temperature. Austempering at this temperature yielded an acicular intermediate product. Additional tests under less exacting conditions were made for an austempering temperature of 950°F where the intermediate product appeared to be very fine pearlite. To determine the effects of tempering on structures containing various amounts of

Jan 1, 1948

By Hojong Kim, Isehaq Al-Nafai, Kwadwo Osseo-Asare

The standard Gibbs free energy of formation (ΔGo f, 298) of bastnasite, (Ce, La, Nd, Pr)FCO3, was estimated using four different methods. The obtained average values were − 1589.5 kJ/mol for CeFCO3, − 1599.5 kJ/mol for LaFCO3, − 1589.1 kJ/mol for NdFCO3, and − 1595.4 kJ/mol for PrFCO3. The value for cerium bastnasite, CeFCO3, was used to construct a potential vs. pH (Eh-pH) diagram to investigate the stability relations of cerium bastnasite. The diagram shows that CeFCO3 is stable in neutral to basic conditions (pH ~ 6.5–11).