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By Leon W. Dupuy

Marquette's first reported the existence of iron In Missouri in 1673. Recorded production wan begun in 1815, increasing in size and importance until 1888, when the low price of iron resulting from Minnesota's production of high-grade ore caused most of the operators to close down. Missouri's iron production came from three types of ore: (l) Brown ores, including the deposits of primary and secondary limonites in southeast and southwest Missouri, (2) hematites of the filled sinks, including the ores of Central Ozark district, and (3) specular ores in porphyry, including the deposits of the St. Francois Mountains.

Jan 1, 1949

By C. Derek Martin

"Predicting the ground response for tunnels in weak shales remains challenging. Predicting the ground response is challenged by difficulties in characterising the material, and our ability to predict deformations that are driven by coupled hydromechanical processes, when this material yields. The techniques that are used for characterizing weak shales are reviewed, and three case histories are examined that demonstrate the behaviour of these weak rocks during tunnelling. A general framework is provided for assessing the squeezing potential for weak shales.1 INTRODUCTIONGeologically, shale is an argillaceous fine-grained sedimentary rock that forms from the compaction of silt and clay-size mineral particles commonly referred to as ""mud"". Because of this grain size, the material is generically classed as Mudstone (Figure 1). Shale is distinguished from other mudstones because it is made up of many thin layers (laminated) and readily splits into thin pieces along the laminations (fissile). While the geological classification of shale appears straightforward, the classification for engineering purposes is often confusing. Underwood (l967) provided the first description of shale that made the distinction between “soil-like” compaction shales and “rock-like ""cemented"" shales. He coined the term ‘clay shale’ to capture the characteristics of hard clay yet recognizing its origin as a shale. In this paper weak shale is synonymous with clay shale and have strengths that typically range from R1 to R2 (1 to 25 MPa). Characterising these materials draws on methods from both soil and rock mechanics."

Jan 1, 2015

By Tom Learmont

The importance of coal in solving our energy problems has been widely discussed; the world demand for food requires increased fertilizer production and the minerals to produce fertilizer must be mined. We have seen an explosive increase in the demand for large stripping equipment. It is appropriate that we review this equipment and determine what can be done to improve productivity. While we have used coal mining as an example in the study, much of the discussion will apply equally to other forms of stripping.

Jan 1, 1975

By Danny Hagood

The drilling of horizontal boreholes as a means of degasification in advance of mining has been tried at Jim Walter Resources, Inc., No. 4 Mine. In a joint venture with the U.S. Bureau of Mines, a series of horizontal drainage boreholes have been drilled in the panels of an advancing continuous miner section with impressive results. The combined methane gas production rate has ranged from 205,000 to 680,000 cfd (cubic feet per day} with individual "in-seam" horizontal holes producing up to 332,000 cfd. The methane liberation from the ribs for the entire panel length has decreased from an average of 8.75 cfm (cubic feet per minute) per 100 feet of entry to 4.05 cfm per 100 feet, a 54 per cent reduction. The actual gas concentration as measure at the surface discharge point normally ranges from 85 per cent to 95 per cent methane. As a consequence of the significant reduction in methane liberation rates from the panels of the section, a 50 per cent increase in productivity from the section has been realized.

Jan 1, 1983

By G. L. Hundley

An anhydrous chlorination process has been developed by the Bureau of Mines for the production of copper, ferric oxide, and sulfur from chalcopyrite. The first part of the process is a chlorination step in which elemental sulfur and a mixture of iron-copper chlorides are produced. This paper describes the second step of the process in which the copper and iron chlorides are reacted with oxygen to selectively convert the iron chloride to ferric oxide and chlorine leaving the copper in the chloride form. The chlorides are pulverized and dropped countercurrent to a flow of oxygen in a vertical 20-cm-diam. reactor at 800° C. By leaching with brine, the copper chloride may be separated from the insoluble iron oxide and reduced to copper powder by electrowinning. It has been demonstrated that 70 to 80 pct of the iron can be converted to oxide in a single-stage operation with a chlorine content in the offgas of 80 pct. After removal of the oxygen, this chlorine could be recycled to the chlorination step. A two-stage operation will convert 98 to 99 pct of the iron in the mixture to insoluble oxides. The offgas from the second stage contains 70 pct chlorine.

Jan 1, 1974

By Koichi Nishimura

Japan's coal reserves are estimated at 8,583 million tons (according to the materials on X World Energy Conference,. 1976). Japan is a long island country in the shape of an elongated cashew nut whose top is pointing to the north and its lower tip is pointing to the west. And her major coal fields are located in the two extreme far parts of Hokkaido in the north and Kyushu in the south. On the other hand, Japan's major industrial center are located in the central part of the country far from either coal-producing areas. This fact places coal a great geographical disadvantage in comparison with petroleum whose refining bases are concentrated on the coastal regions virtually next to major industrial centers.

Jan 1, 1982

By Kumar P. Dharmasena, Haydn N. G. Wadley, Bill W. Choi

"Non-contact eddy current sensing methods have been developed and applied to Cd0.955Zn0.045Te crystal growth to obtain a better understanding of the melt, solid nucleation, and the growth process. The application of this sensor approach relies on a large difference in liquid and solid electrical conductivities near the melting point and requires knowledge of the relationships between the electrical conductivity, melt composition, and temperature. Using a multifrequency encircling eddy current sensor, the electrical conductivities of three different Cd1-xZnxTe (x=0.00, 0.045, and 0.08) alloys were measured as a function of temperature in a laboratory-scale vertical Bridgman furnace. The measured solid and liquid electrical conductivities were then used in electromagnetic finite element models to analyze the multifrequency responses of eddy current sensor designs during the simulated growth of a crystal. These eddy current sensors were fabricated and installed in a vertical Bridgman furnace and used to monitor many Cd0.955Zn0.045 Te growth runs. One sensor was placed in the vicinity of the ampoule tip to detect undercooling/spontaneous nucleation and two other sensors (""absolute"" and ""differential"" designs) placed to monitor the movement/curvature of the liquid-solid interface during crystal growth. The sensor data was used to characterize the initial melt state, detect the onset of nucle-ation, determine the growth velocity, and identify the shape of the interface.IntroductionSingle crystal CdTe and its solid solution Cd1-xZnxTe alloys (0.03<x<0.05) are used as infrared transparent substrates for infrared focal plane array (IRFPA) detectors [1-6] and as solid state y- ray detectors [7-9j. Cd1-xZnxTe substrates are normally ""mined"" from large polycrystalline boules grown by the unseeded directional solidification of Cd1-xZnxTe melts using either a vertical or horizontal Bridgman process [10-14]. The vertical Bridgman method is particularly popular for growing CdTe and its related compounds. In this process, a Cd1-xZnxTe ingot is produced by first melting a charge in the hot zone of the furnace and then vertically translating the furnace (with its associated axial temperature profile) relative to the stationary crucible to cause directional solidification. In spite of many experimental efforts to investigate the relationships between material purity, stoichiometry, the controllable growth parameters (furnace temperature profiles, ampoule geometries/materials, furnace translation rates and starting position) and the resulting material characteristics (grain structure, dislocation densities, IR transmission, macro-segregation etc.), the yield of Cd1-xZnxTe of a quality suitable for large area (e.g. 4 cm x 6 cm) substrates remains low (<10%). Since much of this poor yield is directly associated with the crystal growth process (e.g. melt stoichiometry, solidification velocity, interface shape, temperature gradients, cooling rate, etc.) intensive efforts are under way to improve this technology."

Jan 1, 1997

By Saurav Kumar, Akshay Kumar, Vinayaka R. Kiragi, M. K. Banerjee, Amar Patnaik, Vinod Kumar

Today’s industrial technology offers to optimize and reutilize the resources available in terms of scum that remains after hot rolling in steel rerolling mills in Rajasthan, India. Vast reserves of low-grade coal exist and tons of mill scale are produced everyday after hot rolling in steel rerolling mills in Rajasthan, India. The present research work aimed to optimize the various parameters of solid-state reduction of mill scale using low-grade coal from Rajasthan, India. This study investigates the effect of reduction temperature (850–950 °C in steps of 50 °C), reduction time (60 to 180 min, in step of 60 min), mill scale size (800– 300 μm), and mill scale to coal ratio (1:1, 1:2 and 1:3) on achievable metallic iron percentage and its metallization. A higher percentage of iron content is obtained at a lower particle size of 300 μm. The structural analysis is carried out on 300 μm mill scales using XRD analysis, which shows the percentage of iron is approximately 63%, and metallization above 80% can be obtained under the reduction temperature at 900 °C for 180 min, for 1:3 ratio (mill scale to coal ratio). The chemical composition of the mill scale is obtained using X-ray fluorescence (XRF), and particle sizes as well as distribution of mill scale are determined by scanning electron microscopy (SEM). The elements present in the mill scale are also verified using EDS, which indicates the presence of a major portion of Fe, followed by Fe2O3, Si, and C, respectively.

Aug 14, 2020

By Sunfangze Liu, Xumeng Chen, Yongjun Peng

Efficient separation of naturally hydrophobic gangue, such as talc and carbonaceous materials, from sulphide minerals in flotation is becoming a significant challenge in many processing plants due to the need to process lower grade and more complex ores. Considering the hydrophobic nature of these gangue minerals, prefloating them at the beginning of the flotation circuit in the absence of collectors and rejecting the concentrate is a common practice to remove these gangue minerals. However, sulphide minerals, such as chalcopyrite, can become naturally floatable due to surface oxidation and therefore may float together with naturally hydrophobic gangue. In this study, a new approach was developed to maximize the prefloat of hydrophobic gangue while minimizing the loss of sulphide minerals. The new approach introduced a prefloat cleaner stage where sulphide minerals recovered to the prefloat concentrate was depressed and separated from other hydrophobic gangue minerals at a low pulp potential with the prefloat cleaner tailing fed back to the main sulphide flotation circuit. Flotation tests were conducted using chalcopyrite and organic carbon. The results show that the proposed approach can significantly reduce the loss of valuable minerals in the prefloat flotation without affecting the reject of naturally hydrophobic gangue. Applying pulp potential control at the prefloat cleaner flotation stage also reduces the consumption of reducing agents while minimizing the effect of reducing agents on downstream rougher flotation.

Nov 23, 2020

By R. C. Philp, Allan Gibb

INTRODUCTION. THE term matte is applied to smelting-products so extremely diverse in composition and physical properties that it appears impossible to devise any generic formula to represent, chemically, the manner in which the varied proportions of the almost unlimited possible constituents combine with each other. Mattes produced in copper-smelting, in distinction from those produced in smelting-operations in which the recovery of copper is secondary to that of other metals, cover a narrower range in composition. The copper-content of such mattes vary from 20 to 80 per cent., and even this range is much smaller in general practice since it is found advantageous, when possible, to produce mattes with about. 50 per cent. of copper in the first operation. Further, it is unusual that arsenic or antimony occurs in copper-ores in sufficient proportions to form arsenides or antimonides in such quantities that they will separate out from the furnace-products, as is common in lead-smelting. Generally, the mattes produced in copper-smelting are composed mainly of copper (usually greater than 35 per cent.), iron and sulphur, the remaining elements being usually in proportions sufficiently small to allow of their treatment as impurities, rather than as essential constituents of the mattes. In modern practice of smelting copper-ores in blast-furnaces the tendency is to approach pyritic smelting as nearly as pos¬sible, the furnaces being low and the air supplied being largely in excess of that required for complete combustion of the carbonaceous fuel. Hence the atmosphere of the blast-furnace thus used is usually oxidizing or Dearly neutral? and, as a consequence, the reduction of metallic iron that was a necessary evil of former practice is of unusual occurrence in operations where the main object is the recovery of copper. Hearth-accre-

Nov 1, 1905

By Linn M. Farish

SOVIET RUSSIA reserves must be stupendous. In 1937 I. M. Goubkin placed the reserves of all categories it approximately 48 billion barren which was about twenty billion horn Is in excel:, of all the oil produced in the world since 1857. It is not unlikely in fact it is probable, that these huge stores of petroleum may ultimately be proven to exist within the present boundaries of the U.S.S.R. The size of the country is almost beyond imagination it is 2.7 times as big as the United States. Great sedimentary basins exist in all its different geological provinces, much of which are entirely untested and barely prospected. Oil in commercial quantities is actually produced from formations in every period from the Devonian to the Pleistocene. In the Emba region alone, 300 salt domes are known with an estimate of 700 still to be found. Only 22 of the 300 have been drilled and all showed oil. Of the 22 domes drilled six are now producing. There are 400 mapped structures reported in Azerbaijan

Jan 1, 1940

By Eugene McAuliffe

THE last obtainable figures of the value of the coal mining investment are those contained in the U. S. Census Reports, from data gathered in 1919. The values shown therein and set forth below cover lands and equipment and do not include distribution and marketing facilities. The working capital necessary to meet pay rolls to purchase material and supplies and workmen&apos;s compensation insurance are likewise excluded.

Jan 1, 1926

By Nehemías López, Juan Escala, Nestor Deza, Antonio Bustamante

Desde el inicio de la operación minera en Antamina y a lo largo de los años, se han desarrollado e implementado tecnologías que han ayudado a optimizar los procesos de producción. Uno de los principales retos que se tenía, y en el que actualmente se está trabajando con más de una iniciativa, es reducir la dilución (material estéril enviado a la planta), pérdida (material con contenido metálico enviado a los botaderos de desmonte) y mezcla (representado por bloques de mineral de Cu enviado como CuZn y viceversa) de mineral en el proceso de carguío y acarreo.

Sep 30, 2022

By Ryan C. Stephan, Zach Agioutantis, Christopher Mark

During the past 15 years, roof fall rates have fallen dramatically in US coal mines, particularly in regions where the roof is weakest. The remarkable reduction in the number of roof falls has been accomplished with more effective roof support systems. The purpose of this paper is to present a design methodology that builds on and quantifies the basic roof support concepts that have been successful in the USA. The methodology starts by defining three modes of roof support, based on the roof strength relative to the stress level: (1) suspension, where roof bolts mainly provide skin control for strong roof; (2) beam building, where moderate strength roof can be supported by roof bolts alone; and (3) supplemental support for weak roof. Next, a large database of roof fall histories at a number of mines is used to define the approximate boundaries of these three regimes based on the coal mine roof rating and the depth of cover. Finally, guidelines are presented for site-specific design of support systems within each regime. The new computer package, analysis of mine roof support (AMRS), implements the design methodology.

Sep 29, 2020

By E. C. Wright

FOR many years the cost of making pig iron and steel in the Birmingham district has been about the lowest in the United States. The close proximity of the important raw materials such as coal, iron ore, limestone, and the large available scrap supply made it possible to assemble all of the important ingredients necessary for steel- making with only nominal costs for transportation. Both iron ore and coal were being mined in this district at one time for about $1 per ton from underground operations. At that time mining wages were low everywhere and the labor rate in the South was considerably below that of other mining districts. This situation persisted until the emergence of labor unions as an economic and political force, emigation of southern labor to northern plants, and continued growth of industry in the South in the years following the depression of 1932. Since that time union organizing of miners and steel workers throughout the nation has increased labor costs in mining and steelmaking. This influence has been felt particularly in underground mining operations since the proportion of labor cost to total cost is still high. The previous advantage in basic labor rate in the South has been almost entirely eliminated by the equalization of labor rates in basic industries by national unions. Since 1945 these influences have been especially noticeable in increasing the cost of mining coal and iron ore in the South. The northern steel districts are still being largely supplied with iron ore from the Minnesota open-pit mines and the cost of this ore has not increased nearly as much as the cost of ore obtained from underground mines in Birmingham. A similar situation exists in coal mining; the thinner seams in Alabama are not so amenable to mechanization as the northern mines and, as a result, the output per man-day in southern mines is only about three tons of coal as compared to five or six tons per man-day in the large captive mines of West Vir-

Jan 1, 1950

By S. K. Pan, R. Venugopal, L. A. Kumaraswamidhas, Rakesh Prasad, Chandan Pandey

Cold compressive strength (CCS) and apparent porosity (AP) of pellets are essential properties regarding the burden of blast furnaces. The optimal required values for industries are 2.5 KN CCS and 21% AP. Blaine fineness and firing temperature are the decisive parameters analyzed here. During firing, microstructure phases such as silicate, hematite, and pore are formed. The phase’s grain density during induration influences the pellet’s CCS and AP. The influence of the factors over the response is evaluated by I-optimal (response surface methodology) design. Blaine fineness, firing temperature, pore phase grain density (PPGD), silicate phase grain density (SPGD), and hematite phase grain density (HPGD) affect the CCS and AP of pellets. The RSM-I-optimal predicted responses with a coefficient of determination (R2) of 0.89 for CCS and 0.91 for AP of iron ore pellets. Optimal conditions were Blaine no. = 1668 cm2/g, 1250 °C firing temperature, PPGD value 90 no/mm2, SPGD value 250 no/ mm2, and HPGD value 490 no/mm2, with 4.5 KN CCS 27%. The induration processes were investigated through statistical design of experiments for process optimization. Statistical analysis indicated the direct and interactive influence over CCS and AP. In this study, RSM-I-optimal modeling is used for iron ore pellets processing. The I-optimal prediction could be applied to make the process economical because information is obtained through fewer experiments.

Aug 18, 2020

By S. J. Schatzel, P. W. Jeran, W. P. Diamond, F. E. McCall, F. Garcia, J. C. LaScola, T. P. Mucho

The National Institute for Occupational Safety and Health, Office for Mine Safety and Health Research, is investigating the geologic and mining factors influencing the migration of longwall gob gas. One goal of these studies is to optimize methane drainage strategies to reduce the volume of gob gas that reaches the underground workplace. As part of this research effort, longwall gob gas flow paths in a mine operating in the Pittsburgh Coalbed, PA, were investigated using SF6 tracer gas. Tracer gas released into the ventilation airflow underground generally stayed in the bleeder system and was vented at the associated bleeder fan shafts. Tracer gas injected into an inactive (intaking) gob gas venthole migrated to the two inby producing ventholes on the study panel, indicating that all three ventholes were in communication. The tracer gas that was injected into the gob generally stayed in the gob and only migrated to the ventilation system in response to the venthole on the study panel closest to the injection hole going off production. Tracer gas flow velocities in the longwall gob reservoir and factors influencing the production performance of gob gas ventholes in the study area are also discussed.

By Geraldo Lúcio de Faria

Ao final do processamento termomecânico nos laminadores do tipo Steckel, a tira laminada, já com sua espessura final, é submetida ao resfriamento controlado que geralmente é feito por uma cadeia regulável de aspersores de água. Este resfriamento promove as transformações de fases desejadas para que a microestrutura final do produto laminado confira a ele propriedades mecânicas adequadas para desempenhar com qualidade as funções de aplicação. Neste contexto, o conhecimento dos efeitos da composição química do aço sobre a cinética de transformação de fases possibilitará a adequação de parâmetros operacionais do laminador e do sistema de resfriamento. Reconhecendo a importância deste aspecto, este trabalho estudou a influência da composição química sobre a cinética de transformação de fases dos aços LNE 380 e API X65. Os dois aços foram submetidos a ensaios dilatométricos, metalográficos e de dureza. Ao final do estudo, concluiu-se que, comparados aos efeitos do Nb e Ti, o teor de Mn parece ser o fator com maior influência sobre as temperaturas de início e final tanto de austenitização como de decomposição da austenita durante o resfriamento contínuo. O aumento controlado no teor de Mn possivelmente potencializa o refinamento da microestrutura na etapa de resfriamento.

Oct 30, 2017

By E. D. Musin, S. S. Gudkov, A. V. Epiforov, S. V. Balikov

The standard technology for processing of gold-bearing sulfide raw material has many problems associated with the use of cyanide as a gold lixiviant. Therefore, many tests to find alternative gold recovery methods are being undertaken. This paper describes some technological solutions, which can become alternatives to cyanide technology in the future. Pressure oxidation (POX) of refractory gold-bearing sulfide concentrates from five different Russian gold deposits were investigated. Concentrate 1 was gold-copper concentrate. Concentrate 2 was gold-pyrite concentrate. Concentrates 3-5 were pyrite-arsenopyrite double refractory concentrates. The POX tests were at temperatures of 110, 200 and 220 °C and oxygen pressures of 1.5, 2.4 and 3.0 MPa were carried out. Gold lixiviants, such as chloride, thiosulfate, sulfite and thiocyanate were tested. The recovery of gold from sulfide gold-bearing concentrates by non-cyanide methods was 97- 99%, and from double refractory concentrates, 86-93%. The tested reagents are less toxic than cyanide, and their use will reduce of the cost of gold production. These methods make it possible to recover gold in acidic media, and eliminate the washing operation and POX slurry neutralisation. In addition, precious metals recovery from POX cakes using lead reduction smelting was investigated. It was shown that the “POX-pyrometallurgical” technology for double refractory concentrates processing could be used with recoveries of gold and silver of 97 and 96%, respectively. Keywords: Recovery of gold, refractory sulfide gold-bearing concentrates, double refractory concentrates, pressure oxidation, non-cyanide lixiviants of gold, chloride autoclave leaching, thiosulfate leaching, thiocyanate leaching, sulfite leaching, reduction smelting, POX-pyrometallurgical technology

Jan 1, 2020

By Brajendra Mishra

Molten Salt electrolytic processes offer unique opportunities to extract and refine metals where gaseous or metallothermic reduction, hydro metallurgical extraction and aqueous electrolytic methods are thermodynamically constrained. Production of aluminum and magnesium by molten salt electrolysis are well known commercial processes. Several other reactive metals, such as lanthanides and actinides, as well as beryllium and calcium, make use of molten salt processing for extraction and refining. This presentation describes the science of molten salt chemistry and electrochemistry for winning and refining of several metals. In addition, recovery of metals from waste process salts by molten salt reduction as well as oxidation have been discussed. Material issues in design of molten salt reactors have been included. Various applications have been presented through case studies. Experimental data have been included to justify the suitability as well as limitations of these specific processes.

Jan 1, 2003