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By J Zhou

Gold in sulfide ores is associated predominantly with sulfide minerals and occurs as both microscopic and submicroscopic particles. In non-refractory sulfide ores, gold occurs mainly as coarse- and medium-grained particles. Minute inclusions and submicroscopic gold usually account for a minor portion. In contrast, gold in refractory sulfide ores occurs mainly as minute particles and submicroscopic gold, and microscopic gold usually accounts for an insignificant portion. In gold ores containing carbonaceous material, the preg-robbing nature of carbonaceous material may impose challenges on gold extraction and cause gold losses. To extract gold from refractory sulfide ores, the ore needs to be finely ground and preoxidation is often required. Sulfide host minerals must first be oxidised to create a porous structure through which the cyanide leach solution can penetrate to reach the colloidal gold particles. The oxidation is traditionally achieved by roasting, autoclaving or bacterial oxidation. In carbonaceous sulfide ores exhibiting a preg-robbing nature, the carbonaceous material needs to be treated by roasting, autoclaving or other means to minimise the preg-robbing effect. As a predictive and troubleshooting tool, the gold deportment study plays an important role in gold metallurgy. It determines the deportment of gold in an ore or mill product and identifies the mineralogical issues that may affect or may have affected gold extraction. The information acquired from a gold deportment study can be used to assist in process selection, flow sheet development, recovery improvement and reagent optimisation.CITATION:Zhou, J, 2013. Deportment of gold in sulfide ores and implications for gold extraction, in Proceedings World Gold 2013 , pp 433-442 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 26, 2013

By H. W. McQuaid, E. W. Ehn

It is usually assumed that chemical specifications are sufficient for steel to be used for case carburizing, and if the steel analyzes within the ordinary limits specified for steel for this purpose, no difficulty traceable to the steel used should be encountered in obtaining satisfactory results in the case carburizing and hardening. Much work has been done to determine the effect of various alloying elements on the rate of carbon penetration, etc. but, to our knowledge, little if anything has been published in regard to the effeet of the quality of the steel on the final results in the hardening of case-carburized steel parts. The writers believe that the structure of the case both before and after quenching is greatly affected by the actual condition of the steel itself as made, and that for good results in the case-carburizing and hardening departments, the steel should be of the best possible quality as regards non-metallic impurities. It is the purpose of this paper to prove that the presence of excess dissolved oxides in the steel, as made in the melting furnace, affects permanently the results obtained in carburizing and hardening and that it is possible that the presence of dissolved oxide call result in total unfit-ness of low-carbon steel for case hardening purposes. When races and rolls for roller bearings are made from a low-carbon steel, case carburized and hardened, it is of primary importance that the results of this treatment be of the highest quality. It is necessary, therefore, that in the case-carburizing work each detail be rigorously checked to avoid any defects which would cause the loss of much time and material. The case carburizing with which this paper deals was done in under-fired oil furnaces. The temperature of each furnace is controlled by means of a platinum platinum-rhodium thermocouple, in connection with a potentiometer indicator and potentiometer recorder. The temperature of each furnace is registered every 15 min. by an operator, who is continually checked by the automatic recorders.

Jan 1, 1922

By H. W. McQuaid, E. W. Ehn

It is usually assumed that chemical specifications are sufficient for steel to be used for case carburizing, and if the steel analyzes within the ordinary limits specified for steel for this purpose, no difficulty traceable to the steel used should be encountered in obtaining satisfactory results in the case carburizing and hardening. Much work has been done to determine the effect of various alloying elements on the rate of carbon penetration, etc. but, to our knowledge, little if anything has been published in regard to the effeet of the quality of the steel on the final results in the hardening of case-carburized steel parts. The writers believe that the structure of the case both before and after quenching is greatly affected by the actual condition of the steel itself as made, and that for good results in the case-carburizing and hardening departments, the steel should be of the best possible quality as regards non-metallic impurities. It is the purpose of this paper to prove that the presence of excess dissolved oxides in the steel, as made in the melting furnace, affects permanently the results obtained in carburizing and hardening and that it is possible that the presence of dissolved oxide call result in total unfit-ness of low-carbon steel for case hardening purposes. When races and rolls for roller bearings are made from a low-carbon steel, case carburized and hardened, it is of primary importance that the results of this treatment be of the highest quality. It is necessary, therefore, that in the case-carburizing work each detail be rigorously checked to avoid any defects which would cause the loss of much time and material. The case carburizing with which this paper deals was done in under-fired oil furnaces. The temperature of each furnace is controlled by means of a platinum platinum-rhodium thermocouple, in connection with a potentiometer indicator and potentiometer recorder. The temperature of each furnace is registered every 15 min. by an operator, who is continually checked by the automatic recorders.

Jan 1, 1922

By J. Burns Read, S. Tour

It is the purpose of this paper to summarize, as far as possible, the metallurgical information and experience gained by the Ordnancc Department, during the war, in the manufacture of artillery cartridge cases, to describe the tests to which artillery cartridge cases were put, and to summarize the knowledge and experience gained in this testing. The authors wish to acknowledge the aid given by manufacturers, army officers, and civilian employees of the Department in obtaining data. Artillery cartridge cases are cold drawn from circular disks punched from strips of rolled brass. The rnanufacture involves from 25 to 30 main operations, which are done almost entirely on a punch press. Descriptions of the operations have appeared in various periodical:: and, therefore, will not he given here. After each cupping, or drawing, operation, except the last, the cases are annealed at from 540" to 650" C. (1000" to 1200°F.), to remove all the hardening stresses set up in the metal and to allow complete recrystallization. After each annealing, the cases are pickled in niter cake or sulfuric-acid solution and then washed in water to remove all traces of acid. In some instances, the cases arc then immersed in a cyanide-salt solution, and afterwards rinsed in water, to remove the thin layer of copper that forms on the surface of the cases during the acid pickle. The last cold-drawing operation is followcd by the heading operation which, by flattening the head of the case on the outside, causes the metal to flow on the inside to approximately the proper finished dimensions. The mouth, or open end, is then annealed at 430" to 450" ('. 1800" to 900" F.) by immersion in a salt bath or by gas flames. After being washed, the eases are tapered, when they arc ready for machining, inspection, and testing. Cartridge-case Disks Good disks of proper composition and physical properties are essential to the production of good cartridge cases. The Ordnance Department

Jan 1, 1923

By J. Burns Read, S. Tour

It is the purpose of this paper to summarize, as far as possible, the metallurgical information and experience gained by the Ordnancc Department, during the war, in the manufacture of artillery cartridge cases, to describe the tests to which artillery cartridge cases were put, and to summarize the knowledge and experience gained in this testing. The authors wish to acknowledge the aid given by manufacturers, army officers, and civilian employees of the Department in obtaining data. Artillery cartridge cases are cold drawn from circular disks punched from strips of rolled brass. The rnanufacture involves from 25 to 30 main operations, which are done almost entirely on a punch press. Descriptions of the operations have appeared in various periodical:: and, therefore, will not he given here. After each cupping, or drawing, operation, except the last, the cases are annealed at from 540" to 650" C. (1000" to 1200°F.), to remove all the hardening stresses set up in the metal and to allow complete recrystallization. After each annealing, the cases are pickled in niter cake or sulfuric-acid solution and then washed in water to remove all traces of acid. In some instances, the cases arc then immersed in a cyanide-salt solution, and afterwards rinsed in water, to remove the thin layer of copper that forms on the surface of the cases during the acid pickle. The last cold-drawing operation is followcd by the heading operation which, by flattening the head of the case on the outside, causes the metal to flow on the inside to approximately the proper finished dimensions. The mouth, or open end, is then annealed at 430" to 450" ('. 1800" to 900" F.) by immersion in a salt bath or by gas flames. After being washed, the eases are tapered, when they arc ready for machining, inspection, and testing. Cartridge-case Disks Good disks of proper composition and physical properties are essential to the production of good cartridge cases. The Ordnance Department

Jan 1, 1923

By G. L. Smith, B. Genc, V. Morar, U. Govender

This paper presents a novel holistic healthy human framework for C-suite executives and senior leaders in the minerals industry. The value-add of the framework centres around the integration of inner holistic health and interpersonal holistic health to support and enhance environment, social, and governance transformation, with a focus on the social enterprise. The framework unpacks key components of holistic health and their interlinkages to environment, social, governance, and stakeholder engagement. Insights were gleaned from interviews with 10 C-suite executives, each with over twenty years of experience in mining or business leadership. By applying the holistic healthy human framework, industry leaders can strengthen the social licence to operate and positively transform the industry's public image. Broader application to other sectors is underway.

Oct 2, 2025

By J. B. Griffiths

Clearly there is a tremendous need for assistance in Eastern Europe since most industries must undergo major restructuring. The new governments face many dilemmas, the first task being to establish an order of priorities to deal with the numerous problems at hand. Issues such as the standard of living take low priority compared with market economy and ecological problems. The concept of a Comecon market is now virtually non-existent and trade in roubles ceased from 1991. From this time onwards countries were obliged to trade using free market prices. Governments must also avoid the economic mistakes of countries such as Poland with its high devaluation and lack of economic control and, if possible, contain inflation and unemployment. The privatization of Eastern European enterprises raises considerable difficulties, particularly for large corporations, employing anywhere from 50-100,000 people, which played a major role in the national economy. Whichever method is selected, however, still has to overcome the problem of lack of capital and evaluating the national property. For example, earnings represent only a small percentage of the value of these national industries and thus cannot convert to private ownership without foreign capital investment, either direct or as joint venture capital.

Jan 1, 1992

By E. G. King

Thermodynamic calculations involving the oxides of tungsten and molybdenum have been hampered by lack of accurate entropies and high temperature heat contents. This paper presents work by the Federal Bureau of Mines on new low-temperature heat-capacity data leading to the evaluation of the 298.15° K. entropies of tungsten dioxide and tungsten trioxide, as well as high-temperature heat contents (above 298.15° K.) of molybdenum dioxide, molybdenum tri-oxide, tungsten dioxide, and tungsten trioxide. Included are heats of fusion of the two trioxides. The heats of formation at 298.15° K. of these four oxides are tabulated as measured by Mah4 5/ of this laboratory. Included also are the 298.15° K. entropy of Mo02 measured by Kin 6/ of this laboratory, and that for Mo03 according to Kelley and King.7/ These basic data provide a consistent compilation from which to perform accurate thermodynamic calculations involving these compounds. No previous low-temperature- heat-capacity measurements have been reported for tungsten dioxide. Seltz, Dunkerley, and DeWitt8/ measured the low-temperature heat capacity of tungsten trioxide. The only previously-reported high-temperature heat-content measurements for any of the oxides were conducted by Cosgrove and Snyder,9/ who measured molybdenum trioxide to 1,300° K.

Jan 1, 1960

By B. W. Gandrud

In the summer of 1950, Bureau of Mines engineers visited a number of coal-preparation plants in western Europe and Great Britain to obtain information on European and British coal-cleaning and froth-flotation practices. In view of the growing importance of froth flotation as a process for cleaning fine sizes of coal, it was felt that such data and information would be of value in this country, for, although froth flotation has been adopted for use in a few of our plants, it has not as yet been employed as extensively as in British and European preparation plants. Many of the important coal beds in western Europe, especially in the Ruhr Valley of Germany and in the Dutch coal-mining region of Limburg, Netherlands, are very friable, with the result that the run-of-mine product contains a large proportion of the sizes too fine to be treated successfully by any other method than froth flotation. Furthermore, the relatively high cost of producing coal from these beds has for many years made it economically feasible and desirable to treat the fines by froth flotation, especially in the coking-coal fields.

Jan 1, 1951

By Theodore L. Turner, Joseph H. Swift

A study on a small laboratory scale was made of the use of ammoniacalammonium carbonate for batch leaching Mn from low- grade manganiferous materials ( 6 to 16 pct Mn) obtained from deposits in the southern district of Aroostook County , Maine . These materials were partially reduced at 500 ° to 700 ° C with H₂ or CO and then leached with solutions of NH and CO₂ dissolved in water . Extraction of 80 to 90 pct of the Mn was obtained from some sample materials , but 10 to 34 pct of the iron was also extracted . Material from the Littleton Ridge deposit contained manganese intimately associated with Fe , a condition which contributed to difficulties in obtaining a commercially acceptable product . Extensive investigations of the leach and reduction processes with various mixtures of H₂ and water vapor , and CO and CO₂ , failed to disclose a set of conditions for selectively leaching the manganese . Finely divided metallic Fe was probably produced during the reduction steps so that Fe was leached with the Mn in the subsequent extractions .

Jan 1, 1964

By Louis C. Srichta

The rapid depletion of known high-grade ore deposits of the Tri-State district and the recognized need for development of additional reserves, together with increased interest in open-pit mining of low-grade zinc-lead ores led to Bureau of Mines examination of several abandoned mining areas for possible deposits adapted to strip mining. Examination of the North Empire tract in Cherokee County, suggested that mineralized zones contiguous to previously mined 2e deposits presented probabilities of meeting the requirements for an open-pit mine - hence the tract was selected for further investigation by churn drilling. The zinc-lead deposit on the property is in a sink-hole structure that has been subjected to intense deformation and silicification. Numerous shafts, mine dumps, and surface caves are evidences of exploitation of an extensive area. The reported active mining period was 1895 to 1905. No production records are available, but it is generally stated locally that the value of the mill products exceeded $2,000,000 which represents considerable production, considering the low metal prices of that epoch.

Jan 1, 1950

By Bernardo Martins Braga

O desgaseificador RH é um reator de refino secundário bem estabelecido. Nesse equipamento, gás inerte é usado para promover a circulação de aço entre a panela de aciaria e uma câmara de vácuo. A predição correta da dispersão de gás na perna de subida do RH é importante para a modelagem confiável do processo. O presente trabalho estudou a penetração de gás na perna de subida do RH por meio de modelos físico e matemático. No estudo, foram considerados apenas um ou dois bicos injetores e vazões de gás, por bico, entre 5l/min e 50l/min. Para as condições com um bico injetor, os resultados das duas abordagens mostraram boa concordância qualitativa. Já para as condições com dois bicos injetores, a concordância só foi satisfatória para vazões de até 30l/min por bico. Adicionalmente, os resultados obtidos indicaram que o problema de penetração de gás em modelos matemáticos de desgaseificador RH identificado na literatura está relacionado com erros numéricos e não com falhas na modelagem da física do problema.

Aug 17, 2017

By Sushant Upadhyaya, Deniz Karadeniz, Ahmed Mohamed

Soil setup analysis provides opportunities for efficiencies in pile foundation design and installation. Soil setup gain with time was evaluated as part of the foundation design and installation for twelve bridges along the Interstate 64 corridor between York County and Newport News in Virginia. The substructure elements of the bridges consist of driven precast prestressed concrete piles or H-piles. This case study describes lessons learned to understand the soil setup phenomenon during the installation of the piles in coastal plain. We were able to make expedited decisions during construction by analyzing previously performed pile dynamic analyzer (PDA) test results within the project alignment. Data evaluation included analyses of PDA data obtained from initial driving and restrike after a few hours to 5 weeks. The test data showed pile resistance increase up to twice in most cases and as high as four times in some cases. Foundation design and acceptance based on soil setup can provide opportunities for cost savings and advanced scheduling during construction.

By M. J. Bradley, P. H. Dike

THE art of melting nonferrous metals, in smelting, casting, and in compounding of alloys, is highly dependent on a knowledge of the temperature of the metal. This knowledge may reside in the experience and judgment of the melter, or it may be based on measurement by suitable instruments. It-is our purpose to discuss briefly the instruments available for such measurements, and more at length the present, practice in molten metals, without recommendation. In the limits of time and space allotted, we can do little more than mention the available methods of measurement that are directly applicable in this field. In the 1939 edition of the Metals Handbook, issued by the American Society for Metals, pages 285-310, there is a more extensive discussion of pyrometry than can be attempted here, which should be referred to for details we must omit. For reasons that will appear, thermoelectric pyrometry will constitute the major portion of our discussion of the subject, only limited attention being given to radiation or optical pyrometry. METHODS OF MEASUREMENT THERMOELECTRIC PYROMETRY A thermocouple consists of two dissimilar wires, or a wire inside a tube of a dissimilar material, joined together at one end, which is placed in the region or medium where the temperature is to be measured, while the other ends are connected through suitable lead wires to a voltage-measuring device, which may be a millivoltmeter or a potentiometer. An electromotive force is generated in the circuit, which is proportional to the difference in temperature between the hot junction and the junctions of the lead wires to the measuring instrument. If this latter temperature is maintained constant, the e.m.f. measured varies only with the temperature of the hot junction. Every thermoelectric pyrometer is calibrated for a particular cold-junction temperature such as 0°F., 32°F. or 75°F., but usually it is more practical to compensate instrumentally over the probable range of cold-junction temperatures than to maintain the junction at the particular temperature for which the instrument was calibrated. Thermocouple Materials Only a very few pairs of metals are in frequent use for pyrometric measurements. The most generally used are iron-constantan for temperatures up to 1500°F. in oxidizing and up to 1800°F. in reducing atmospheres and chromel-alumel, which may be used in oxidizing atmospheres at temperatures up to 2400°F. for intermittent service. The accuracy of the latter deteriorates rapidly at temperatures above 2200°F. Platinum vs. platinum-rhodium thermocouples may be used up to a temperature of 3000°F , but they are easily contaminated by slow absorption of

Jan 1, 1946

By G. M. Kintz

The data in this circular were taken from publications of the United States Bureau of Mines and published annual reports of the Wyoming State Inspector of Coal Mines. The tables included are complete only' with regard to major disasters; the Bureau of Mines considers a major disaster one in which 5 or more men are killed. However, minor disasters and gas ignitions recorded in these publications are included. It is known that a number of gas ignitions have occurred of which no record is available. This is one of a series of papers by the Bureau of Mines giving by States available data regarding coal-mine explosions. This information is published in condensed form in the belief that it may be of vale to mine operators in preventing future coal-mine explosions.

Jan 1, 1934

By Leonardo Matsumota

Este trabalho aborda um estudo de caso sobre a transferência do conhecimento siderúrgico de colaboradores da empresa para o sistema que realiza o controle de produção da Usina de Cubatão. Este processo de transferência foi realizado em etapas até a implantação do sistema que registra os principais eventos realizados pelas máquinas operacionais. Estes registros são armazenados em banco de dados e com o uso de ferramentas, podem ser apresentados em relatórios e gráficos. Com isso, a empresa possui um sistema de produção muito confiável, por ter condição de analisar e diagnosticar cada etapa do processo de produção e acompanhar com precisão as falhas e acertos operacionais. Quando há estabilidade no processo e todos os eventos acontecem de acordo com a condição normal de operação, o sistema possibilita um controle aprimorado no consumo de gás e da produtividade. O método utilizado é baseado em um projeto de experimentos que examina a influência dos principais parâmetros de controle no processo de produção industrial.

Jul 30, 2018

By Tuanhui Wang, Qiwei Wang, Quanrui Liu, Jianhui Xu, Chao Wang, Yu Liu, Yuefeng Li

Rockburst is a highly destructive geological hazard that can cause casualties and equipment damage. To achieve highaccuracy discrimination of rockburst intensity, this article proposes an improved model that addresses the inefficient maximum membership principle used in traditional rockburst fuzzy evaluation models. The stress coefficient σθ/σc, brittleness coefficient σc/σt, and elastic deformation energy index Wet are selected as evaluation indicators for rockburst classification. Subjective and objective weights are obtained using the Delphi method and entropy weight method (EWM). Three types of membership function distribution forms are then used to obtain the membership degrees of each indicator to rockburst grades: trapezoidal membership function (TMF), normal membership function (NMF), and quadratic parabolic membership function (QPMF). Finally, six traditional models and six improved models are established using the maximum membership principle (MMP) and weighted average-maximum membership principle combination evaluation principle (WMP), respectively. Based on the analysis of 100 sets of rockburst field data, the accuracy, precision, recall, and F1-score of the improved evaluation model are increased by 11.3%, 0.097, 0.068, and 0.089, respectively, compared to the traditional model. The Delphi-NMF-WMP model is selected as the best model, with four performance indices reaching 97.0%, 0.979, 0.979, and 0.978. The best model is applied to evaluate the rockburst intensity of the Cangling Tunnel, Dongguashan Copper Mine, and Jiangbian Hydropower Station Diversion Tunnel, with evaluation results consistent with the actual situation, demonstrating the reliability and scientificity of the model.

Feb 28, 2024

By W. Hodge Caraway

This report presents the results of an evaluation of several indirect methods of measuring the water content of oil-reservoir rocks. The water content of oil-base cores is considered to be most nearly representative of the water content of the undisturbed petroleum reservoir and therefore, the direct method of measuring the volumes of water in cores cut in oil-base drilling fluid was adopted as a standard for comparison. The indirect methods evaluated included (1) displacement through a semipermeable membrane by air, (2) centrifuge, (3) evaporation, (4) mercury injection, (5) chloride dilution and (6) electric logs. Approximately 270 samples of cores from petroleum-reservoir rocks were used in the study. The cores, most of which were cut with oil-base mud in the hole, were taken from oilfields in California, Texas Gulf coast, Colorado, Oklahoma, and Alaska.

Jan 1, 1959

By W. E. Robinson

A laboratory study wan made to determine whether drying and preheating Colorado oil shale with waste retort gases has any appreciable effect on its oil yield. Samples of crushed oil shale were heated at subretorting temperatures in a specially constructed electric furnace by gases similar in composition to waste gases from oil-shale retorts. The results of this study showed that preheating oil shale with nitrogen or a reducing mixture had no effect upon the oil or water yield. However, oxygen in the preheating gas caused a decrease of oil and an increase of water. In general, the oil yield decreased with (1) increase in oxygen content of the heating gases, (2) increase in temperature of the heating gas, (3) increase in heating time, and (4) decrease in the particle size of tho shale. The decrease in oil and the increase in water resulting from preheating were due to oxidation of the benzene-insoluble organic material (kerogen) rather than to oxidation of the benzene-soluble organic material (natural bitumen) in the shale, A small amount of oil was volatilized during preheating, which would constitute an additional loss if prober precautions were not taken to recover it. The results obtained in this laboratory study indicate that oil shale can be preheated without appreciable decrease in oil yield by proper selection of preheating conditions.

Jan 1, 1951

By Maurice L. Pinel, Thomas T. Read, Thomas A. Wright

THE erroneous, but until recently widely prevalent, belief that iron castings were first made in Europe in the fourteenth century has been adequately refuted in a number of earlier papers;1,11,12 but except for an unpublished metallographic study by the late William Campbell, and a phosphorus analysis by T. A. Wright of the metal of the Han dynasty cast-iron stove described by Laufer,2 nothing was known of either the chemical composition or the metallographic structure of the metal of any ancient iron casting, although data on castings of recent manufacture are abundantly available. The metal of the stove, which had been buried in a grave for at least 15 centuries, was so corroded that it seemed inadvisable to publish the results on it until more and better specimens from other ancient castings could be obtained. During a journey through China, extending from Peking in the north to Canton in the south and Cheng-tu, Ssu-chuan, in the west, in the late summer and autumn of 1936, one of us (T. T. Read) was fortunate enough to obtain, and bring home for study, nine castings, all more than 1000 years old, of which the date of manufacture is precisely known because of inscriptions cast in them, another that lacks a dated inscription, but of which the date, as explained below, can be otherwise established, and a specimen from the largest iron casting ever made," which is also dated. The period covered by this suite of specimens extends from 502 to 1093 A.D. In addition, a sample was obtained from a casting of date unknown, but which was certainly cast before 1000 A.D. and possibly as early as the third century A.D. A detailed description of these specimens is as follows: 1. 502 A.D. A pair (right and left) of recumbent lions (Fig. 1). Base 7 ¼ by 14 3/8 in., height over-all 5 ½ in., weight 26 lb. each. The translation of the inscription on the base is: "Made on the twenty-fourth day of the seventh month of the third year of Ching Ming of Great Wei" (Sept. 11, 502 A.D.).

Jan 1, 1938