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By L. Cáceres, G. Leinenweber, P. Bustamante

"Given the severe scarcity of fresh water sources in Northern Chile the use of seawater has become the only alternative to allow mining expansion. This option however poses several technological challenges as a result of the high concentration of natural salts that promote various forms of metal corrosion. Therefore the steel piping protection has been a constant challenge for design engineers responsible for solving the problems of corrosion. Known protection alternatives are varied and expensive, a few of them are rubber coatings, protection based centrifuged concrete, extra wall thickness of pipes in combination with corrosion inhibitors, extra wall thickness of pipes without using corrosion inhibitors, and the use of highly corrosion resistant steel materials.In this framework the aim was to study the corrosion kinetics of carbon steel pipe API 5L X70 under electrochemical and weight loss testing. The test conditions include a range of seawater velocities between 0.2 to 3.0 m/s.For electrochemical experiments the API 5L X70 steel specimen was a 4 mm diameter disk embedded in an 8 mm diameter Teflon rod and exposed to seawater. Duplicated coupons were placed in a standard test apparatus that was built according to the standard ASTM D 2688 – 94.The main results were: a) corrosion mechanism explained in terms of the counterparts partial processes which are the hydrogen evolution and oxygen reduction reaction; b) for the test specimen a corrosion band like feature that suggest a lateral dispersion of aggressive solutions from corrosion pits; c) a range of corrosion rates between 1 and 1.96 mm/year for flow rates between 0.2 and 3.0 m/s; and d) a convenient inhibitor dose between 20–25 mg/L for optimum inhibition efficiency to obtain a maximum value of 80% for corrosion efficiency."

Jan 1, 2016

By PALMER LARSEN

INDEX TO GEOPHYSICAL ABSTRACTS

May 1, 1931

Increasing depths and mechanization of underground mines have led to the production of large amounts of gaseous and particulate contaminants. Over 100 000 lives have been lost due to methane gas and dust explosions in coal mine workings in both the United States and Canada since 1900. There is, therefore, the need to constantly assess and evaluate the performance of existing mine ventilation systems to maintain safe and acceptable mine environmental conditions. This paper advances research initiatives in the control of methane gas in underground mine environments. It uses the results of continuous monitoring of methane gas concentrations conducted in selected coal mines in North America to assess the effectiveness of existing auxiliary ventilation systems to control methane gas concentrations. The results show that the average quantities of fresh air required to dilute, disperse and remove methane gas concentrations within set levels of one minute varied from 5.43 m3/sec. to 27.97 m3/sec. in the development headings. The average dilution times in the headings studied were less than eight minutes. The calculated dilution efficiencies of the auxiliary ventilation systems in the headings varied from 12% to 139%. These efficiencies ranged from poor to excellent. This implies that the auxiliary ventilation systems were capable of controlling the methane gas concentrations below statutory levels but may not be able to cope with large and unusual methane gas concentrations in the headings. This study is significant in the control of methane gas and coal dust explosions in coal mines.

Sep 1, 2001

By Thomas S. Nye

Mineral exploration in the United States relies heavily on theoretical geologic concepts and indirect methods such as geophysics and geochemical prospecting, as there are few exposed areas of mineralization which have not already been explored at least once. In Mexico ore-grade samples can be cut at the surface on vein, replacement, and disseminated types of deposits in many areas. Here the problem is not in finding a mineralized area but in deciding which mineralized area can be explored and developed at the least risk and cost, and have the greatest profit potential, within the framework of Mexican mineral economics and government policies. Mexico's min¬eral industry is regulated through a system of permits for various phases of mineral exploitation, and by taxes. This regulation and its effects are not unlike those which may be expected in the United States if present legislative and administrative trends continue.

Jan 1, 1972

By Heinz Hoberg, Fred Ulrich Schneider, Rudolf Diegel

The risk of contamination of dumped tailings and ground water by coal flotation reagents has been investigated by using the 14C-radiotracer method for adsorption and desorption measurements. The results indicate, that a high amount of the reagent components adsorbed on the tailings if there was no coal in the pulp. In coal flotation however a competitive adsorption behaviour could be observed, with the effect that only a low quantity of reagents adsorbed on the tailings. Mobilization tests showed, that only small quantities of reagents could be desorbed by rinsing water. Therefore the contamination of ground water should be low.

Jan 1, 1995

By Grant Goddard

Cameco?s ?Double U? Strategy ? Double existing production ? To 40 million lbs U3O8 annually ? By 2018 ? Existing operations ? Saskatchewan ? United States ? Kazakhstan ? Projects under evaluation ? McArthur River expansion ? Kintyre (Australia) ? Inkai Block 3 (Kazakhstan) ? Development properties ? Cigar Lake project Measures of Success ? Safe, healthy and rewarding workplace ? Supportive communities ? Clean environment ? Outstanding financial performance

Nov 1, 2011

Despite modest improvements in the performance of domestic interest rates and gross national product,1 fixed investment in domestic producers' durable equipment continued to weaken during the second quarter of 1982 and declined at a 12.8 percent annual rate compared with the first quarter.2 Large declines occurred during the second quarter in expenditures on many of the major mineral-consuming industries such as aircraft, computers, agricultural and construction machinery and mining and oil field equipment. These data appear to be consistent with the low level of business investment plans for 1982 reported in the DOC's Bureau of Economic Analysis survey of expenditures on new plant and equipment.3 Domestic and foreign industrial production and mineral industry production activities continued to decline in the most recent period because of weak demand conditions (Tables 1 and 2). The U.S. mining production index declined 7.7 percent between April and June as compared with 1.2 percent for total U.S. industrial production (Table 1).

Jan 1, 1982

By Richard S. Kunter

The Bulldog CIP plant treats the slime portion of current tailings and reclaimed flotation tailings from the adjoining 350 tpd (3.67 kg/s) silver-lead flotation mill. Changes to the dredge reclaimer, pulp storage tank and trash removal system have allowed an increase in tonnage treated to a sustained 460tpd (4.83kg/s). CIP feed is 3-4 oz/T Ag (102.9-137.1 ppm). Following conventional cyanidation, carbon is added to the slurry. Silver loaded carbon is stripped in atmospheric-pressure vessels using hot caustic cyanide. Silver recovery from this solution is by Zadra- type cells. Some of the modifications to the plant and operating techniques are discussed.

Jan 1, 1981

By Frank G. Miller

Controlling natural-water drives to effect efficient and economic production of petroleum, through wells, from reservoir sands and rocks is a problem of major importance in the oil-producing industry. Water-drive fields are characterized by large quantities of mobile water under high pressure immediately below the oil in the flanks or extraneous parts of reservoir formations, Hence, the water, which is in fluid connection with the oil and a source of a large proportion of the energy available for moving it, advances up-structure to replace it. This phenomenon of water moving crestward into the oil-bearing parts of the reservoir and replacing oil is termed edgewater encroachment. The mechanism by which oil is flushed out and continually replaced by water as the hydocarbon content of the field is depleted must be understood if natural-water drives arc to be used successfully to, induce efficient recovery of oil from its reservoir rocks. Until recently, the function of water in the production of oil has been somewhat obscure and was not given the consideration it deserved in early petroleum production-research programs because of the greater importance associated with and the effort devoted to investigations concerning the relations of natural gas to production of oil. Thus, with virtually no fundamental information at hand, it is not surprising that at first edgewater was considered a necessary evil, and the manner in which it was dealt with depended largely on the experience of the operators. During the intervening years, however, practical information on encroachment of edgewater in oil sands has been widely disseminated as a result of studies of oil-field depletion, and many theories pertaining to petroleum-reservoir energy and performance have been advanced; these theories necessarily included consideration of edgewater as an integral -art of the reservoir fluids and a source of energy for propelling hydrocarbon fluids through the reservoir and to the surface of the ground.

Jan 1, 1941

By Ren G. Dong, Kristine M. Krajnak, Dan Welcome

Continual occupational exposure to vibrating hand tools can damage the neural, vascular and other soft tissues of the fingers. Rat tail models have been developed to investigate the biological responses of the tissues to vibration.1-2 However, the biodynamic response of the tail relative to that of the human fingers has not been characterized. The objective of this pilot study was to compare the transmissibilities of rat tails measured via a scanning laser vibrometer to those of human fingers gripping a handle. Methods In Part I of this experiment, four male Sprague Dawley rats (6 weeks old) were exposed to discrete 5g-rms sinusoids of 32, 63, 125, 160, 250, and 500 Hz. The rats were restrained in Broome-style restrainers with their tails constrained without compression to an exposure platform via elastic straps as shown in Figure 1. The platform was attached to a vertically vibrating shaker. The vibration was measured for the array of points shown in Figure 1 using a scanning laser vibrometer (Polytec) and the transmissibility calculated for each point on the tail relative to the reference points on the platform. In Part II, three male human subjects were exposed at the frequencies specified in Part I - with the addition of 1000 Hz - at a magnitude at the ANSI <0.5-hr limit up to 63 Hz, after which the acceleration was held constant at 5g-rms. The subjects gripped an instrumented handle at 20 N as shown in Figure 2. The transmissibility was calculated relative to the reference points on the handle. [ ]

Jan 6, 2006

By Hugh Jones

Mine planners are challenged to hold two seemingly opposing objectives: maximizing the mine?s operational efficiency while minimizing post-closure impacts. One of the most effective approaches to meet these objectives is to plan for mine closure from the start. Mine closure is typically viewed as the process that happens in the period of time when the operational stage of a mine is ending and the final decommissioning and mine rehabilitation is being undertaken. In reality, it is a continuous series of activities that begins with preplanning prior to the project?s design and construction and ends when long-term site stability is achieved and a self-sustaining ecosystem is established. Putting this model into practice as early as possible can significantly reduce the financial burden of mine closure and rehabilitation.

Jan 1, 2011

By Jugal Kar

Yilgam Star treats a gold bearing ore which has an association with pyrohotite and pentlandite (Fe,Ni)9S8 Nickel behaves similar to gold in cyanide solution, it leaches in cyanide to form a number of species. It adsorbs like the noble metals on carbon. During smelting Nickel causes significant problems in the crucible as the melting point of nickel is much higher (1452 °C) than gold (1040 CC). The crucible became overheated, holed and increases furnace downtime. To overcome such dif­ficulties an investigation was carried out to reduce the amount of nickel on steel wool during stripping. Yilgam Star has got I.P.S. high pressure zadra stripping system which works on 400 kpa, at 140 °C. The trend of gold and nickel profiles has been observed with varying caustic concentrations. The gold and nickel profile has been monitored with the addition of cyanide in the stripping liquor. It has been ascertained that at lower caustic levels the nickel ion remains in solution and is subsequently not electro­won. The cyanide concentration of0.4% (Wt/Vol) keeps nickel ion in solution and induces metallic nickel to produce nickel ion as NiCN.

Jan 1, 1995

Five conclusions that emerged from ADL&apos;s Contractor Noise Measurements Assessment done for the Bureau of Mines and the 7 December 1971 Bureau of Mines Contractors&apos; Round Table Meeting in Boulder, Colorado were: ? a limited amount of good data has been obtained for characterizing the noise environment for electromagnetic (EM) coal mine operational/emergency communications systems; ? significant noise date gaps still exist; ? suitable instrumentation and data analysis methods are available for filling these data gaps; ? the immediate and most important data gaps should be filled by means of a timely field measurement effort that is purposely limited in scope and duration; ? this field measurement effort should preferably be carried out by a team knowledgeable and experienced in coal mine EM noise measurements.

Jan 1, 1972

By Frank G. Miller

Controlling natural-water drives to effect efficient and economic production of petroleum, through wells, from reservoir sands and rocks is a problem of major importance in the oil-producing industry. Water-drive fields are characterized by large quantities of mobile water under high pressure immediately below the oil in the flanks or extraneous parts of reservoir formations. Hence, the water, which is in fluid connection with the oil and a source of a large proportion of the energy available for moving it, advances up-structure to replace it. This phenomenon of water moving crestward into the oil-bearing parts of the reservoir and replacing oil is termed edgewater encroachment. The mechanism by which oil is flushed out and continually replaced by water as the hydrocarbon content of the field is depleted must be understood if natural-water drives arc to be used successfully to, induce efficient recovery of oil from its reservoir rocks. Until recently, the function of water in the production of oil has been somewhat obscure and was not given the consideration it deserved in early petroleum production-research programs because of the greater importance associated with and the effort devoted to investigations concerning the relations of natural gas to production of oil. Thus, with virtually no fundamental information at hand, it is not surprising that at first edgewater was considered a necessary evil, and the manner in which it was dealt with depended largely on the experience of the operators. During the intervening years, however, .practical information on encroachment of edgewater in oil sands has been widely disseminated as a result of studies of oil-field depletion, and many theories pertaining to petroleum-reservoir energy and performance have been advanced; these theories necessarily included consideration of edgewater as an integral part of the reservoir fluids and a source of energy for propelling hydrocarbon fluids through the reservoir and to the surface of the ground.

Jan 1, 1941

By Ángel Fernández

En Minera Coimolache se generan aproximadamente 700 t de residuos sólidos al año. El 50% de estos corresponde a residuos orgánicos, los que mediante fermentación anaeróbica con microorganismos eficaces son transformados en un plazo muy breve en bioabonos sólidos y líquidos (solución ecológica). Los microrganismos eficaces presentes en estos bioabonos han mejorado notablemente los procesos de siembra, incrementando hasta en un 361% la densidad poblacional de la misma. Por otro lado, dado que la actividad microbiana generada compite por el oxígeno del suelo reduciendo de forma colateral la generación de drenaje ácido de roca (el pH incrementó de 2.02 a 7.55 y se redujeron metales como el Fe, Pb, Cu y Zn), se ha obtenido una solución económica al emplear suelos abonados, como sustituto de la cal, para la cobertura de depósitos en proceso de cierre.

Jul 30, 2018

By Gino Merello

Dado que los cargadores frontales LHD son los equipos encargados de extraer gran parte de la producción en la mina subterránea El Teniente, se justifica el estudio de confiabilidad, mantenibilidad y disponibilidad que permita optimizar la actual estrategía de mantenimiento. En ese sentido, el presente texto señala la optimización de la estrategia de mantenimiento a través de la metodología de revisar continuamente los parámetros básicos del motor diesel y la condición físico-química del lubricante de motor. También se monitoreó con una frecuencia de dos días el estado general de los equipos, con el fin de detectar prematuramente algún tipo de daño que se derive de la implementación de la nueva estrategia.

Jun 1, 2014

By J. Drew

Oregon Resources Corporation (ORC), an industrial minerals mining company, is currently engaged in the development of a new process design that will allow the unique paleo-beach placer deposits of southwestern Oregon to be mined efficiently and economically, creating an additional domestic source for chromite, garnet, and zircon. Engineering design has been guided by the variable geology and mineralogy of the paleo-beach placer deposits as well as the need for a dry tailing scheme that resolves a lack of water resources at the placer locations and at the same time eliminates the need for slurry settling ponds, typical of paleo-beach placer operations in North America. Metallurgical study of the placer material was grouped into four distinct samples based on marine terrace deposition, geological facies, and mineralogy. Because the metallurgical samples represented the extremes likely to be encountered in all future Oregon paleo-beach placer ores, the process design is highly dynamic and will successfully adjust to meet the production needs. Water availability at the mining area is seasonal and will not support a typical placer operation?s water requirement needs for heavy mineral concentration. For this reason, ORC has developed a plan to construct the ore processing facilities near Coos Bay, where a municipal source of water is available. Raw ore will be transported from the mining sites approximately twenty miles one way to the processing facility with return loads hauling tailings back to the active pit. The need to haul dry tailings, return dry material to the pit for reclamation, and limit the amount of water being purchased from the municipality has driven the design of a unique water reclamation system. BACKGROUND Location and Access Economic concentrations of ?black sand? or heavy mineral (minerals with specific gravity greater than 2.85) have been recognized and studied in marine placers from Coos Bay to the mouth of the Rogue River, a distance of approximately 75 miles along the southern Oregon coast (Hornor, 1918; Griggs, 1945)(Figure 1). ORC will begin mining existing reserves approximately 20 miles south of Coos Bay in a region known locally as Seven Devils. Ore will be trucked north to the processing site near Coos Bay via use of existing county and state roads, including U.S. 101. The available facilities at the processing site include highway, rail, municipal water and electricity, natural gas, and a deep water port. At the time of this writing, the rail line had been abandoned, but was being pursued by the International Port of Coos Bay. It is anticipated that this will be serviceable at some time in the future. History The southern Oregon marine placers have garnered the interests of miners since 1852, when present day beaches were exploited for gold. The beach deposits were small and irregular in nature and were easily washed away by the major storms the coast endures during the winter months (Hornor, 1918). [ ] In the 1920?s, deposits at the beach were followed upstream to their paleo-beach terrace origins (Pardee, 1934). These terrace placers were mined, but with little success, as the cost of mining and processing was greater than at the present day beach deposits. The greatest effort to understand and delineate the paleo-beach terrace placers came during World War II. As the need for a domestic source of steel hardening chromite was evident, the heavy mineral bearing placers of southwestern Oregon provided just that. The U.S. Geological Survey, under guidance from the Oregon Department of Geology and Mineral Industries, began exploration drilling of the paleo-beach terraces in 1940 (Griggs, 1945). This work was part of the investigation of strategic mineral deposits and would ultimately supply much needed chromite for the war efforts. The first mining efforts began in 1943 by the Humphreys Gold Corporation and the Krome Corporation (Griggs, 1945). Black sand

Jan 1, 2009

By B. Anameric, S. Kawatra

Pig iron nuggets, which have similar chemical and physical properties with blast furnace pig iron, were produced by a single step heat treatment of self reducing – fluxing dried greenballs. During this single step heat treatment the transformation of self reducing fluxing dried greenballs into pig iron nuggets did not take place instantaneously. Rather, it was composed of three transformation stages, (1) transformation of self reducing – fluxing dried greenballs into direct reduced iron (DRI), (2) transformation of DRI into transition direct reduced iron (TDRI), and (3) transformation of TDRI into pig iron nuggets. Thus, the objective of this research was to investigate these transformation mechanisms by analyzing the transformation stage products. The transformation stage products were produced at a constant furnace temperature of 1425°C and various furnace residence times. They were characterized according to their microstructure, microhardness and apparent density. The changes in the product’s physical and chemical properties with furnace residence time were utilized in understanding the transformation behavior, the chemical events that took place and the controlling mechanisms. It was determined that the transformations were dictated by the changes in the slag viscosity and wetting properties, and by carbon diffusion into metallized areas.

Jan 1, 2007

By M J. Schultz, R L. Rude, D M. Tomko

The US Mine Safety and Health Administration (MSHA) conducted compliance assistance diesel particulate matter (DPM) sampling throughout the underground metal and non-metal mining industry. Based on that sampling, MSHA identified mines that were having difficulty meeting the DPM limit. To provide further assistance, MSHA then visited approximately 60 of the mines that were experiencing difficulty complying with the DPM standard. As part of these visits, DPM exposures were measured and control technologies for DPM were observed and assessed. Controls consisted of ventilation, clean engines, environmental cabs, alternative fuels, diesel particulate filters (DPF) and work practices. The focus of the follow-up compliance assistance visits was to assess control effectiveness and to make recommendations to mines experiencing difficulty in meeting the DPM standard. At each mine visited, the ventilation controls were evaluated, engine emissions were determined for equipment in use, environmental cabs were examined, and operational practices were noted. Additionally, control technologies, including alternative fuels and DPF were evaluated in several mines. A comparison was made of mine and section airflow to equipment particulate indices. Based on engine emissions, horsepower and operating time, the contribution of individual engine emissions to total emissions was made. Environmental cab integrity, positive pressure and air filtration systems were checked and operational practices relating to DPM exposure were assessed. This paper summarises the preference and magnitudes of controls that were typically used or needed for successful control of DPM. Additionally, results of the assessments of alternative fuels (including bio-diesel and water emulsion fuels) and DPF are presented.

Jan 1, 2005

By J. Marks

The measurement of greenhouse gas (GHG) emissions from primary aluminium production and inventory of these emissions of carbon dioxide and PF Cs have become an important issue for primary aluminium producers. Most global producers have either voluntary emission goals or emissions limits established through national regulatory requirements. International good practices for inventory of these emissions for national governments are established through the Intergovernmental Panel on Climate Change (IPCC). The current good practices, last updated in 2000, are being revised and are expected to be adopted by governments in the spring of 2006. There are a number of changes expected in the guidance that will impact how facilities account for their GHG emissions. This paper describes the changes to the guidance and the implications of these changes for aluminium producers.

Jan 1, 2006