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By J. R. Cain

In every process for making steel there are one or more stages where the metal is exposed to gas of one kind or another. Thus, in the open-hearth furnace, the carbon dioxide and water vapor in the products of combustion are oxidizing toward the ferrous and manganous oxides in the slag, tending to convert these to higher oxides; the higher oxides then , oxidize the steel, so that indirectly the products of combustion are oxidizing toward the steel. In the Bessemer process, there is direct contact of air and steel; also, the water vapor in the air blown into the converter is continually decomposed by the molten steel, yielding hydrogen and ferrous oxide, both of which are in part taken up by the metal. In the electric-furnace processes, there is always more or less air in contact with the slag covering the metal, and this air and the gaseous reaction products from it are dissolved in the slag to some extent and thus transmitted in part to the steel. In the crucible processes, there is always entrapped air in the charges and the crucibles are more or less permeable to the gaseous products of combustion from the furnace. In all the processes of manufacture, the molten metal is exposed to air while tapping into ladles and ingot molds and has an opportunity to saturate itself with air or with gaseous or solid products generated by chemical reactions between air and steel. Sievertsl has shown that molten metals requirc but a few seconds to saturate themselves with a surrounding gas. No one familiar with the operations at a steel plant needs to be reminded of the important role that gases play at all stages. The familiar "boil" of open-hearth furnaces, due to evolution of carbon monoxide when iron ore is added to the molten steel; the spectacular operation of the Bessemer converter brought about entirely by a gaseous reagent; the almost magic effect of small quantities of silicon, manganese, or aluminum added to the molten metal in ladle or furnace in quickly preventing bubbling and evolution of gases; the unwelcome phenomena of blowholes in ingots that have not been properly manufactured—these

Jan 1, 1920

By Gary E. Sherman

This report presents a Bureau of Mines study on the cost of mine permitting and compliance with environmental regulations in Alaska. It discusses permitting requirements and procedures for placer and lode mines. Placer miners must comply with recently established (1988) water quality regulations and effluent treatment requirements. To estimate the impact differing treatment options (no recycle, 100% recycling, and flocculation) have on a placer mine's rate of return, three models (1,500, 1,000, and 500 yd3/d) were simulated. Rates of return for these models show a marked decrease as effluent treatment is increased. The incremental increase in operating cost from one treatment option to the next is relatively small; however the opportunity cost of lost production if' significant and accounts for the decreasing rate of return with increased effluent treatment. Lode mines face greater costs for permitting and compliance than similarly sized placer mines as a result of the impact of the operation. Direct permitting costs for lode mines range from 2 to 6% of total project cost, with 4% the most common figure cited by industry. Total costs for permitting and compliance are approximately double those for permitting. Indirect costs associated with compliance include mitigation, monitoring, and reclamation.

Jan 1, 1991

By Ueki S

Underground coal gasification (UCG) is a promising process for obtai- ning energy from coal, which is either unmineable with current mining techno- logy or uneconomic to recover, using conventional methods, in the present energy market situation. There are several coal fields, which could become new coal reserves, if the UCG process were successfully applied. In the 1960's Japanese researchers made a number of basic studies and field tests into UCG, although not all of them produced favourable results. This paper reviews Japanese research on UCG. This includs basic studies into coal gasification using a small, tube reactor fed by air and oxygen, and also large scale model stu- dies(reactor size of 8.Om x 2.4m x 1.5 m). Field test results from Akabira colliery in Hokkaido and a feasibility study of power generation using UCG from a coal field in Hokkaido are also Presented.

Jan 1, 1987

By J. W. D. Groenewald, L. Auret, B. S. Lindner, E. C. Nienaber

Mineral processing plants have complicated control strategies, with different control layers, multiple interacting loops, and feedforward disturbance rejection. The complicated control strategies mean that oscillations can arise and propagate to multiple loops and degrade the control performance. Oscillation detection techniques, such as the spectral envelope method, can be applied to detect oscillations within an observation window. However, the start- and end-points of the oscillations within the observation window cannot be identified with current oscillation detection techniques. The start- and end-points would be useful to label the oscillatory intervals, and then to use these labels to identify process conditions associated with the oscillation. In this paper, a pattern recognition technique, Density-Based Spatial Clustering of Applications with Noise (DBSCAN), was used to label oscillation intervals. An oscillation diagnosis workflow combining spectral envelope and DBSCAN was demonstrated on an industrial case study of oscillations in a flotation circuit concentrate sump. The workflow successfully detected the oscillation, labelled the oscillatory intervals, and enabled accurate root cause analysis. The impact of time series features, namely the signal power ratio () and the oscillation frequency, on the performance and optimal parameter selection of DBSCAN was also investigated. Low oscillation frequencies and low s negatively affected the performance of DBSCAN. Additionally, the results indicated that higher oscillation frequency was related to higher optimal values for the lag parameter. Keywords: Oscillation diagnosis, process monitoring, data mining, clustering, flotation control

Jan 1, 2020

To improve a miner's chances for survival in an emergency by providing an improved self-rescuer device that functions in a toxic or oxygen-deficient atmosphere. The Approach: Development of a compact, lightweight apparatus which produces oxygen by using the wearer's breath in a chemical reaction. How It Works: The device is designed to cause the user's breath, which contains water vapor and carbon dioxide, to react with potassium superoxide (K02) to produce oxygen in quantities sufficient to sustain the wearer for one hour. The system is a closed circuit and does not depend on "screening" of noxious gases. To use the device, the miner opens the top and

Jan 1, 1974

By E J. Y Koh, G J. McLachlan, E Amini, N Beaton

Preconcentration greatly reduces the ore mass input to the processing plant while upgrading the grade. One of the commonly used methods of preconcentration is optical sorting. These methods rely on optical sensors which classify the material stream into “accept-reject” streams. Currently, it is common to use near infrared (NIR) or colour cameras to classify streams based on reflectance or colour thresholds set by experts. The imaging is done through line-scan sensors where the material is scanned on a belt or a chute. Then, a separation apparatus like a diverter gate or air jet is controlled to separate the streams according to the classification made by the algorithm. Separation efficiency is dependent on the classification algorithm. Existing classification algorithms rely on low-level feature discrimination like observing individual pixel values for reflectance or colour hues. This limits discrimination between minerals with low contrast in colour. Human experts perform mineral segmentation using texture, colour distribution and shape, but it is difficult to translate these visual rules to mathematical thresholds. Deep learning methods like Convolutional Neural Networks (CNNs) provide high-level feature discrimination similar to a human expert. Instead of relying on pre-defined features, the CNNs learn complex features from the dataset. CNNs can construct a hierarchy of features based on pixel clusters to learn texture, shapes, and colour spectrums of the mineral grain surface to provide better separation. In this study, a state-of-the-art deep learning instance segmentation method is used to outline boundaries and classify grains from the background (mineral segmentation). The algorithm is trained on images collected from a flotation feed of a gold deposit, where the gold is mechanically locked inside pyrite. This method can process on-line video inputs at 5 frames per second to provide a live grade. The proposed method is inexpensive as it only uses a camera and a desktop computer.

Nov 10, 2020

The purpose of this paper is to outline some aspects of the experimental worlr that has been carried out in the mineral dressing laboratory at M'ount. Morgan during recent years.The subject matter has been dealt with under the following headings:1. Comminution of various mill products.2. The application of sulphur dioxide as a flotation reagent.3. Heavy-media separation.4. Bulk flotation of sulphide ores.COMMINUTION OF VARIOUS MILL PRODUCTSThe following data were cbtained by processing fractions of reserve grade ore.Granular TailingIn Table 1 are shown the results of tests on material representative of average grade tailing. In the first test (H1 ) the granular tailing was floated as received and in the second test (Ha) the tailing was ground prior to flotation.

Jan 1, 1952

By R. O. Dannenberg

This report describes aperiments by the Bureau of Mines and reviews theoretical aspects of the use of organophosphate solvent extraction for recovering beryllium from sulfate leach liquors. The leach liquors were prepared by sulfuric acid leaching of lime-sintered low-tenor beryl flotation concentrates. The experimental work on sulfate leach liquors showed that the acidic esters of organophosphates extracted beryllium slowly but in preference to aluminum. Three common alkylphosphoric acids, di- (2-ethylhexyl) (EHPA), heptadecyl (HDPA), and dodecyl (DDPA), in order of decrmsing selectivity, yielded a partial separation of beryllium from aluminum.

Jan 1, 1962

By Sigmund J. Andersen, Eva A. Mørtsell, Jostein Røyset, Randi Holmestad, Oddvin Reiso, Yanjun Li, Øyvind Paulsen, Calin D. Marioara

"With the purpose of increasing the extrudability of lean alloys, we reduce levels of the alloying elements Mg and Si in a 6xxx extrusion alloy. To avoid sacrificing strength, we investigate the compensating effect of smaller amounts of lithium and germanium, alone and in combination. Recent studies by atomically resolved high angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) together with density functional theory (DFT) calculations have demonstrated that while Li replaces Mg, Ge substitutes Si in the columns in the hardening ß’’-phase. Several studies have shown that Ge replaces Si in other precipitates as well, and that both Li and Ge promote precipitation and can improve macroscopic properties, like strength and thermal stability. The scope of the current work has been to investigate and document the combined effect of the two alloying elements. Of the investigated alloys, the one containing both elements displayed highest hardness, corresponding with a significant increase in precipitate number density. We used HAADF-STEM to determine the extent of Li and Ge in the precipitate structures.INTRODUCTION The two most important alloying agents, with respect to age hardening of the 6xxx alloy series, are Mg and Si. In general, 6xxx alloys are formed into their final shapes by rolling or extrusion, before being age-hardened at elevated temperatures around 180°C. The hardening effect during this stage is due to the formation of metastable, semi-coherent, precipitate needles along the three < 001>Al directions generally following the precipitation sequence (Marioara, Nordmark, Andersen, & Holmestad, 2006): Supersaturated solid solution ? atomic clusters ? Guinier-Preston-zones (pre-ß”) (Edwards, Stiller, Dunlop, & Couper, 1998) (Marioara, Andersen, Jansen, & Zandbergen, 2001) ? ß” (Andersen, et al., 1998) (Hasting, et al., 2009) ? ß’ (Vissers, Huis, Jansen, & H. W. Zandbergen, 2007), U1 (Andersen, Marioara, Vissers, Frøseth, & Zandbergen, 2007), U2 (Andersen, Marioara, Frøseth, Vissers, & Zandbergen, 2005), B’ (Vissers, Marioara, Andersen, & Holmestad, 2008) ? ß, Si (stable)"

Jan 1, 2018

This is the sixth in a series of reports on properties of commercial motor fuels, made in accordance with a cooperative agreement between the Cooperative Fuel Research (C.F.R.) Committee and the Bureau of Mines of the Department of the Interior. The first report gave data on motor gasolines sold during the winter of 1935-36.3/ The present report covers 54 brands of gasoline represented by 1,480 samples plus those from the Pacific Coast, which were averaged by the Pacific Coast Technical Group before being submitted and are published exactly as they were submitted. In some areas reports were received from 8 to 10 companies on the same brands of gasoline, whereas in other areas only one company reported on a brand. Thus, it can be seen that some of the data are more representative than others. The inclusion of data from several cities within some of the districts has improved the report by reducing the number of brands reported by only one company. Several changes have been made in the districts. A new district, Memphis, Tenn., has been formed to include Arkansas and western Tennessee. The Rocky Mountain areas have been divided into three sections. Salt Lake City and Denver form the Middle Rocky Mountain district; Laramie, Wyo., Idaho, Montana, and Spokane, Wash., are included in the North Rocky Mountain district, and Arizona, New Mexico, and El Paso, Tex., have been combined to represent the South Rocky Mountain district. The Cleveland district has been expanded to include Ohio an,"- Indiana. Eastern Pennsylvania, Maryland, and northern Virginia are included in the Washington (D. C.) district. The Atlanta district includes Georgia, South Carolina; Mississippi, and northern Florida.

Jan 1, 1938

The method of investigation was to study the distribution of ore in great detail, to make a thorough structural study of the lode and the mine area, and then to compare the results of the two studies. Such a comparison usually reveals a very close relationship between geological structure and ore distribution, and can often lead to important conclusions which would not be reached in the ordinary working of a mine.The Triton mine lies 30 miles E.N.E. of Cue, or 380 miles N.W. of Kalgoorlie, in typical pre-Cambrian rocks, consisting of gTeenstone lavas and tuft&apos;s, interbedded with slates and some sediments, and intruded by granite and porphyry. Fig. 1 (at end of paper) is a longitudinal section of the mine and shows that the workings consist of the main North Emu and the smaller South Emu, separated by a distance of about 1 of a mile. Both orebodies occur on the same lode, which strikes north and south and dips practically vertically. On the same line, and of 1/2 a mile and a mile respectively to the north of the North Emu, are the small Rand and North Rand workings, where a big width of lode material has proved to be very low grade. In the North Emu the lode width averages 12 to 15 feet; it is seldom less than 5 feet and in places reaches 30 feet. In the South Emu the lode is wide, but only portion of it is payable.The lode is a mineralised bed occurring between massive lava flows on the east and a mixed series of tuft&apos;s and thin lava flows on the west. The lode material is hard, fine grained, and dark coloured, and generally has a faint banding which is believed to indicate a tuft&apos;aceous origin of the original lode rock. Microscopic examination shows that the original lode rock has undergone considerable albitisation;&apos; there has also been considerable formation of biotite which gives the lode material a characteristic sheen. The mineralisation consists of abundant fine pyrite, which is auriferous, and a lesser development of pyrrhotite which is, however, barren of gold.THE OREBODIES AND THEIR CHARACTERISTICSThe distribution of ore is best studied from gold contours, as these reveal features that cannot be detected in an ordinary assay section. Gold contours (see Fig. 3) are developed&apos; by plotting the width and grade of all development and stoping assays throughout the mine on a longitudinal projection, representing each sample by a coloured dot according to a suitably chosen range of assay values, and then outlining areas of similarly coloured dots (see H. J. C. Conolly, Econ. Geol., April, 1936). Both width and grade must be taken into account and the simplest method of gold contouring is to use dwt.lft. values, but difficulties arise here with big widths of low grade and small widths of high grade ore. To choose an extreme case, 30 ft. of 2 dwts. and 2 ft. of 30 dwts. both equal 60 dwts.lft., and would therefore be given the same value in dwt.lft. contouring...

Jan 1, 1943

By M. A. Trevits

During the time period from 1990-2007, 1601 reportable fires occurred in the U.S. mining industry (an average of 89 fires per year). The leading causes of U.S. mine fires were flame cutting and welding operations, frictional heating and ignitions, electrical shorts, mobile equipment malfunctions, and spontaneous combustion. The fact that mine fires continue to occur with an alarming regularity reinforces the importance of recognizing and eliminating the potential hazards and the overall need for improved fire control and suppression technology to ensure the best possible outcome during a mine fire. The National Institute for Occupational Safety and Health (NIOSH) is conducting an evolving comprehensive program of research that is addressing mine fire prevention, detection, management and suppression. This paper presents a summary of recent research accomplishments and provides an overview of the next phase of the NIOSH mine fire research program.

Jan 1, 2008

By R. A. Vik

The influence of thermal treatments on the grindability of low-grade hematitic iron ores from Michigan and Minnesota was examined in bench-scale tests. Treatment factors were roasting temperature, roasting atmosphere, and ore cooling conditions. Bond ball mill grindability and work indices were used as response indicators in evaluating the condition of the ore. Of the three treatment factors evaluated, roasting atmosphere, which brought about the con version of iron oxides to magnetite, had the most significant effect; roasting temperature had the next most important effect; and cooling condition had the least effect. Optimum grindability was obtained with reduced-quenched products of both ores at 650° C, near the alpha-beta phase transformation of quartz.

Jan 1, 1971

By Donald F. Reed

Deposits of gray hematite occur in two districts in Talladega County, Ala., the Emauhee-Tallasechatch and Weewoka, both in the; vicinity of Wintorboro, 50 miles east of Birmingham. The deposits were investigated by the Bureau of Mines in 1945 and 1944. Approximately 15,000 feet of diamond drilling was done and 6,000 linear feet of trenches excavated and sampled.

Jan 1, 1949

By H. R. Peiffer, R. Geckle

The silver phase of silver and finely divided alumina composites is shown to grow as single crystabs upon solidification from the melt. These crystals grow without the aid of an externally applied thermal gradient or a mold. The single-crystal growth is more readily disrupted as the alumina content varies from the optimum concentration of 20 wt pct. Pretreatment such as variation of fabrication pressure, and presintering of the specimens appear to play a lesser role in this phenomenon. In actual practice the growth of single crystals of metals from the melt is a tedious, painstaking process.&apos; Care must be taken to insure the proper thermal gradients and rate of growth in a vibration-free environment. Excellent single crystals can be grown when these variables are controlled. When a second insoluble and finely divided phase is present in the melt the growth of single crystals is difficult, if not impossible, even under the most favorable conditions outlined above. During the past few years, a composite of silver and alumina has demonstrated an ability to resist flow even though the major phase, silver, is mo1ten. 2 A more surprising feature of this material is the ease with which single crystals of silver grow upon cooling the composite from temperatures above the melting point of silver to temperatures near room temperature. Observations have been made that demonstrate that single crystals of silver will grow even when conditions most unfavorable for growth of pure silver crystals exist. The crystals grown in this manner are imperfect in that a great deal of subgrain structure exists. It is the purpose of this manuscript to qualitatively describe this process and to attempt to isolate the influencing factors of this behavior. MATERIAL PREPARATION The composite material is prepared by powder-metallurgical techniques. Two items of great importance are the introduction of oxygen into the system and the obvious need for a thorough mixing of the metallic and refractory oxide phases. The oxygen is necessary in order that the silver wets the alumina. Without oxygen the phases separate and the material shows no unusual properties. In order to supply the needed oxygen the silver is added in the form of silver oxide which is readily decomposed to oxygen and silver upon heating. The silver oxide is readily obtained in a finely divided form that allows a uniform mixture of the alumina and silver oxide to be prepared. The correct ratio of alumina to silver oxide is mixed in the presence of alcohol in an ordinary food blender. The mixture has the consistency of a thin slurry and after mixing for approximately 20 min is dried and pressed into billets at various pressures. As is shown in Fig. 1, there is no limit to the shape of the specimens obtainable as single crystals. These billets are heated in air in a predeter-

Jan 1, 1964

By J. J. Bodmer

Although the similarity between puzzolana, or trass, and blastfurnace slag, as seen by comparison of the analyses, is a well-known fact, blast-furnace slag has not been used commercially as a substitute for those cementing materials. The reason, the writer apprehends, lies in the fact that unless such slag is disintegrated or subdivided by rolls, the process must either be too costly, or the material is not in a fit and proper condition for the purpose. In order to produce a reliable slag cement, the slag must be ground together with the lime into an impalpable powder. The subdivided slag must, therefore, be perfectly dry, and, at the same time, friable. The stronger the hydraulic properties of the lime, the more reliable the slag cement will be, and practice has proved, that the slag from a gray-iron furnace gives the best results. The slag cement which has given the results shown in the annexed table, under pressure tests, was composed of six parts of slag, from a blast-furnace producing No. 3 foundry iron, and one part of lime, of medium hydraulic properties. The above-described class of cement bears storing as long as most Portland cements, and the cheapness of its production is self-evident.

By J. J. Bodmer

ALTHOUGH the similarity between puzzolana, or trass, and blast-furnace slag, as seen by comparison of the analyses, is a well-known fact, blast-furnace slag has not been used commercially as a substitute for those cementing materials. The reason, the writer apprehends, lies in the fact that unless such slag is disintegrated or subdivided by rolls, the process must either be too costly, or the material is not in a fit and proper condition for the purpose. In order to produce a reliable slag cement, the slag must be ground together with the lime into an impalpable powder. The subdivided slag must, therefore, be perfectly dry, and, at the same time, friable. The stronger the hydraulic properties of the lime, the more reliable the slag cement will be, and practice has proved, that the slag from a gray-iron furnace gives the best results. The slag cement which has given the results shown in the annexed table, under pressure tests, was composed of six parts of slag, from a blast-furnace producing No. 3 foundry iron, and one part of lime, of medium hydraulic properties. The above-described class of cement bears storing as long as most Portland cements, and the cheapness of its production is self-evident.

Jan 1, 1874

By R. R. Oder, R. E. Jamison, E. D. Brandner

This paper presents preliminary test results obtained with a 0.38 kg/s (3000 lb-hr) beta prototype MagMill™. In processing Upper Freeport coal the beta prototype recovered 82% of the weight of the feed and 91% of the heat content while reducing the potential emissions of sulfur, kgSO2/GJ(lbSO2/MBtu), by 61%. Pyritic sulfur in the MagMill™ product was reduced by 78% compared to that in the feed. For all runs, the mill product was controlled between 70 to 80% finer than 74 µ particle size. Recoveries of mercury, arsenic, and selenium ranged from 35 to 45% of that in the feed. Power draw was reduced by 26% and mill throughput was increased by 9% compared to the pulverizer operating with no magnetic separator attached.

Jan 1, 2000

By Lloyd A. Morley

This Bureau of Mines publication presents a comprehensive review of mine electrical power-system theory and practice. It discusses fundamental theory and the vital aspects to be considered in planning and designing mine electrical power systems. The report is divided into three major sections. The first presents the history of electricity in mining and the fundamentals of electrical phenomena and components. The second focuses on power-system components: motors, grounding systems, cables, and protective equipment and devices. The final section includes mine power-center equipment, switchhouses and substations, batteries, and mine maintenance.

Jan 1, 2003

By V. Perdikatsis

The aim of this paper is the study of the pollution of soils in greenhouses because of the use of pesticides. The degree of pollution was studied in relation with the mineralogical and pedologic properties of the soil. The study was con-ducted in the region of Kountoura, Palaiochora, situated in the south of the prefecture of Hania/Greece. Several samples of soil, originated from 4 greenhouses were analyzed. 5 pesticides with organic drastic compounds were chosen for analytical determination using GC-MS from 18 which were applied in total during the period of sampling. It was concluded that the adsorption of pesticides in the soil of greenhouses is connected with the percentage of the clay fraction and the content of organic carbon.

Jan 1, 2006