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By F. Chen, L. J. Gaydos, D. C. Kuhn, Demersm L. M., S. C. Sun

"Summary: In this report the differential regulation of NF-KB and nitric oxide (NO) was investigated in the mouse macrophage cell line RAW 264.7 following exposure to a mineral dust (silica) and /or an endotoxin (Lipopolysaccharide, LPS). The results indicated that silica and LPS can significantly induce the activation of NF-KB as well as elicit enhanced production of NO in RAW 264.7 cells as part of an early inflammatory response mechanism. A 24-hour time-course study showed that NO release from these cells continued to increase following the initial stimulus by LPS or silica. In contrast, activation of NF-KB was maximal at 6 hours and then showed a steady decline to 24 hours. The production of NO was suppressed by protease inhibitor and antioxidant, both of which block the activation of NF-KB. Surprisingly, the use of an NO synthase inhibitor resulted in an enhancement of NF-JCB activation. These findings suggest that NO produced in macrophage cells in response to an inflammatory stimulus like silica or LPS my be linked to a negative feedback role on the activation of NF-KB. It is now accepted that nitric oxide (NO) plays a pivotal role in the inflammation response process when macrophage cells are activated by a pro-inflammatory stimulus (l). Production of NO is dependent on the activity of the enzyme nitric oxide synthase (NOS). Up until now, at least three distinct genes have been described which encode different isoforms of NOS. NOS has been cloned from a variety of different mammalian cells, including constitutive neuron NOS, constitutive endothelium NOS and inducible NOS (2). Macrophages appear to be the principal cellular source for the inducible form of NOS (iNOS) activated in response to an inflammatory producing event. The mechanisms subserving the regulation of the iNOS gene and NO production have been under intense investigation in recent years (3-5). Several binding sites for transcriptional factors have been identified in the promoter region of iNOS gene, including NF-lCB, AP-1, NF-IL6, Oct-I to cite a few (5). NF-KB appears to play a"

Dec 1, 1996

By Olanrewaju A. Ojo, Xu Wang, Jian Xin Dong, Lina Zhang, Jerzy A. Szpunar

"The influence of crystallographic orientation on the pitting corrosion behavior of Ni-Fe-Cr alloy 028 was studied by a combination of X-ray diffraction (XRD), electron backscatter diffraction (EBSD), potentiodynamic polarization technique and atomic force microscopy (AFM). The results show that there is anisotropy of pitting corrosion that strongly depends on crystallographic orientation of surface planes. The distribution of pits frequency in standard stereographic triangle shows that the crystallographic planes close to {100} are more prone to pitting corrosion compared to planes of {110} and {111}. The calculation of surface energy (001) and (111) shows that the planes of high packing density of atoms have low surface energy with concomitant strong resistance to pitting corrosion. A correlation function between crystallographic orientation and pitting corrosion susceptibility suggests a method not only to predict the pitting resistance of a known textured materials, but also to improve corrosion resistance by controlling materials texture.INTRODUCTIONNickel-iron-chromium(Ni-Fe-Cr) alloys are widely used in various industries and engineering sectors due to their combination of good mechanical properties and high corrosion resistance(Hibner, 2001; Thomas, 2006; Ghosh, 2005).Ni-Fe-Cr alloy 028 (alloy 028)has such important characteristics worth mentioning. Alloy 028 contains high amounts of nickel, copper and molybdenum which improve its resistant to corrosion attack in reducing medium, and presence of high level of chromium makes it more resistant to oxidizing species. Moreover, alloy 028 is less expensive because of higher amount of iron compared to other similar alloys. Currently, alloy 028 is manufactured as evaporator tubes applied in the phosphoric acid production; production tubing and casing used in deep and sour gas wells; heat exchangers employed in nuclear power plants, and seawater-carrying piping and seawater-cooled heat exchangers (Bankiewicz, 2012; Kivisäkk, 2003; Gómez, 2003; Xian, 2012; Bellezze, 2004)"

Jan 1, 2017

By J. B. Austin

IT is now well established, chiefly through the work of Davenport and Bain,1 that the influence of temperature upon the rate of transformation of austenite to ferrite at constant temperature is represented by a curve of the type shown in Fig. 5 of Tech. Pub. 589; and the reasons for this general shape have been discussed by them in a qualitative way. Thus, the upper part, or nose, of the curve is the resultant of two factors of which the rate of change with temperature is not the same, and by analogy with other like cases it is almost certain that these factors are: (1) the chemical potential, or driving force, of the transformation, which is zero at the equilibrium temperature and increases rapidly as the temperature falls below this point; and (2) a factor analogous to viscosity, or resistance of the crystal lattice to a change in structure, which also increases as the temperature is lowered. Just below the equilibrium temperature this virtual "viscosity" of the metal is relatively low-that is, the metal offers little resistance to a change in lattice-but the driving force is also small, and the net result is that the reaction proceeds slowly. As the temperature is lowered the magnitude of both factors increases; but at first the driving force increases more rapidly than the resistance and the reaction is observed to proceed more rapidly. At lower temperatures, however, the resistance begins to increase faster than the driving force, and eventually, at the nose of the curve, overbalances it, causing the reaction to proceed more and more slowly thereafter. This concept is somewhat, though not completely, analogous to that employed in certain electrical cases where the precise factors are known and are separately measurable. The current I (in amperes or coulombs per second) flowing through a given wire is proportional to the impressed potential, or driving force E, and is inversely proportional to the resistance R of the wire; that is, I = E/R. Stated in a slightly different way,

Jan 1, 1935

By K. J. Craig, M. A. Swart, Q. G. Reynolds, L. Hockaday

A solar reflector soiling study was carried out at a ferromanganese smelter in South Africa to assess the soiling rates at different locations around the plant. Several meteorological parameters were monitored to give insight into the conditions that lead to increased soiling. Mineralogical characterization of dust samples collected from the reflectors and the atmosphere revealed that only a certain size fraction is of importance with regard to soiling, and that the dust can be attributed to both raw materials and smelter products. Proximity to the dust source was the primary driver for increased soiling. The site that experienced the most soiling was very close to raw material heaps; this was deemed an outlier and was excluded from the summary statistics. The secondary driver for increased soiling was location relative to the smelter dust sources and the wind’s direction and speed. The reflector set at the best location experienced 13.1% less soiling than the set at the ‘worst’ (but still feasible) location, represented by an averaged mean daily reflectance loss of 0.0186. The study revealed that while there are periods of intense soiling at this particular site, proper planning of reflector location in relation to the smelter dust sources can significantly mitigate the soiling rate.

Jun 5, 2023

By Shengping Li, Wei Lv, Gangqiang Fan, Xuewei Lv, Yingyi Zhang

The electrical conductivity of high titania slag, as being an important fundamental physical property utilized in the theoretical understanding of mass transfer phenomena and requirement of practical electric smelting processes, were measured by AC Impedance Spectroscopy using four-electrode method for ternary TiO2–FeO–Ti2O3 slag system based on 85 type of titania slag in Panzhihua in this work. The experiment results show that the slags have a high magnitude of the order of 80–180 s/cm−1 in the whole experimental temperature range from 1523 to 2013 K. The Ti2O3 exhibits very strong effect on increasing the electrical conductivity of high-titania slag since the specific values averagely increase by 55 s/cm−1 with corresponding Ti2O3 content range from 10 to 16 wt%. the X-ray diffraction gram and phases calculated by FactSage are presented and interpreted to discuss the impact of phase change on the electrical conductivity.

Mar 1, 2017

By A. V. Neretin

This paper is a continuation and extention of the previous paper on energy-efficient placer mining methods which was presented in 2007 at the World Gold Conference in Cairns, Australia (Nere-tin, 2007a). The paper reports the results only on gravel processing as they were not fully discussed in the previous paper. It is common knowledge that placer gold mining requires processing of large tonnages of gold-bearing gravels by wash plants of different types. In Russia, gold-bearing gravels are mostly disintegrated and screened by the following types of wash plants: a water canon, a derocker or a scrubber trommel. Gold-bearing gravel processing is regarded as highly energy-intensive due to high energy consumption for transportation of large tonnage of material and high pressure water flow rate. The industries requiring a significant expenditure of energy normally estimate the process efficiency by energy consumption per product unit. In order to obtain quantitative data on energy consumption for gravel processing and to estimate placer mining costs, in 2003~2006 four placer gold mines located in the Irkutsk Region were thoroughly investigated through time and motion studies. At all these placer mines gravels were processed by a water canon, a derocker or a scrubber trommel. The objective of the study was to investigate the following parameters: ? wash plant throughput rate per hour; ? hourly diesel fuel and power consumption per cubic meter of gravel processed; ? volume per cent and shape of oversize material; ? different combinations of gravel processing methods. The results from this study were as follows: ? specific energy consumption per cubic metre of gravel processed for different combinations of gravel processing methods was estimated; ? a correlation between energy consumption and unit cost of gravel processing was determined; ? effect of yield and shape of oversize material on wash plant throughput rate per hour was de-fined; ? energy-efficient gravel processing methods were developed. Based on these results, an improved method of gold-bearing gravel processing was proposed. Implementation of this method at a placer mine saved US$ 123 000 in operating expenses only during a short-time Siberian placer mining season. At the same time, this method improved gravel disintegration, screening and processing operations used at the mine. Another advantage of the pro-posed method was higher gold recovery due to reduced yield of undersize material. In order to improve efficiency of gravel processing, a wash system including a derocker for primary gravel processing and a lightweight scrubber trommel was developed. There are two economic benefits of replacing water cannons with the proposed wash system. The first benefit includes lower operating costs for gravel processing due to lower specific energy consumption, while the second benefit is lower gold losses during slurrifying (disintegration and screening) and sluicing of the undersize material.

Jan 1, 2014

By Barbara Peszko, Tadeusz Tumidajski

"Various methods are used to identify the grain composition of fine-grained materials because so far the best notion of the grain size has not found and there is no single method to define grain size. In practice the most important are the following grain sizes: sieve diameter dt, effective diameter de, substitute diameter d2 and statistical diameter dst. The mentioned sizes are connected with the methods of analyses. Methods are correct but measure of different diameters of grain and their results are different.The most important methods of granulometric composition analyses are the following: the sieve analysis, the sedimentation method and the conductometric (Coulter-Counter) methods. In each of these methods various physical features connected with the grain size are measured.Sizes of grains defined by different formulas or measurement methods are associated mutually by dependencies, which are results of differences in their determination or calculation ways.In order to determine principles of results comparison the classification analysis results on linearly or non-linearly connected was made. Analyses which results demonstrate the same type of grain size distribution are treated as linearly connected. It is based on the general formulae which determines the probability density function of random variable which is the function of another random variable having the known density function.In order to show the difference in the grain composition of the same material qualified by different methods, three methods of investigations were distinguished. They are: the sieve analysis performed on precise sieves, the sedimentation analysis performed by means of a sedimentation balance “Sartorius” and the microscopic analysis performed after preparing a microscopic slide where the grain size was measured by the Martin’s method.The materials selected for the analysis were quartzite and glass, which are the material of high purity.The obtained results of mentioned above three types of analyses were approximated by distribution function of four distributions: Weibull, log-normal, cut Weibull and Gaudin-Schuhman."

Jan 1, 2003

By Matsushita Y, Maeda M, Sano N

The present study was carried out to explore the possible separate recovery of iron and phosphorus (as gas) from BOF slag using graphite crucibles or graphite powders in the presence of a tin bath. The last is consider- ed to enhance the activity of phosphorus in iron reduced from slag or not to absorb the phosphorus vapour readily. When the slag was reduced in a graphite crucible in contact with a tin bath, the phosphorus reduced from the slag was carried away in CO explosively generated by the reduc- tion of iron oxide. When graphite powder was used as the reductant instead, 78% of the phosphorus was removed from slag, only 3% of which was absorb- ed into the tin bath. The rest left the system as gas. Gaseous dephosphorization depends on the area of contact between slag and reductant as cll n.u the amount of the latter. the reduction behaviour was directly observed, using an X ray transmission technique, to conlirm the reaction mechanism.

Jan 1, 1980

By K Ionkov

The oolitic iron ore reserves in Lisakovsky, North Kazakhstan represent quite a challenging deposit both from a technological and from a resource point of view. The difficulties in processing such types of ore are connected with the extremely fine dissemination of phosphorus and gangue minerals inside the oolitic formations. The goethite crystals are cemented in their structure by aluminosilicates with quartz and other gangue minerals and dissemination is so fine that they are not separable by physical methods. The laboratory tests performed for dephosphorisation show that the combination of alkaline roasting followed by low intensity magnetic separation and acid leaching enables the obtaining of high grade iron concentrate. The magnetic separation performed ahead of leaching is effi cient as a means of buffering the high pH by washing out the soluble salts and the excess of base and after leaching facilitates the removal of secondary liberated gangue minerals in the non-magnetic fraction. As a consequence, phosphorous content is dropped to a more acceptable level for the ferrous metallurgy and iron grade and recovery reach 61.6 and 80.8 per cent respectively.

Jul 11, 2011

By Vilela A. C F

In the present work, the process of dephosphorisation of stainless steel was developed in laboratory scale by adopting a high frequence induction furnace, using BaCO3 base flux. By using BaCO3 - CaO - BaC12 - Fe2O3 Flux of about 110 g/Kg-metal, 30 per cent dephosphorisation degree was obtained a stainless steel containing 18,8 per cent Cr and carbon between 0,08 and 2,0 per cent. In addition, a dessulfurisation degree of 89 per cent was achieved too.

Jan 1, 1991

By A. McLean, A. Hue, K. Le, Y. D. Yang, P. Wu

While the treatment of relatively inexpensive ferrosilicon alloys is a potential refining route in order to generate solar grade silicon, phosphorus is one of the more difficult impurities to remove by conventional processing. In this project, the use of an electromagnetic levitation technique was used to investigate the dephosphorization of ferrosilicon alloy droplets exposed for various times and temperatures to a hydrogen-argon gas mixture. It was found that approximately 40% of the phosphorus was removed from an 85%Si-15%Fe alloy after 20 minutes exposure at approximately 1673K, to a gas mixture containing 48.5% hydrogen. Further dephosphorization is expected with longer reaction times. The effect of increasing temperature was found to be insignificant, although processing at lower temperatures is not only economically advantageous, it also decreases evaporative silicon losses, thus resulting in a more efficient process.

Jan 1, 2015

By Wen Xuan

Oolitic iron ores have significant economical importance because of their extensive resources in the world. However, their utilisation is often quite limited due to the high content of phosphorus inside. The phosphorus is often finely disseminated in the oolite structure and generally not liberated in the form of free particles. The iron ore used in this work is a typical oolitic goethitic iron ore with high phosphorus. The process of phosphorus removal from this ore is difficult because the phosphorus is not present as distinct minerals. As a result, no physical beneficiation process is able to separate the phosphorus from the iron bearing phases. The current concentrate contains low iron grade (Fe ~49%) and high phosphorus content (P 0.7~0.8%). The acid leaching is a potential way to dissolve phosphorus. Previous studies have shown that the thermal treatment makes the phosphorus more accessible for the acids and enables more efficient phosphorus dissolution. Some chemical additives are reported to enhance this phenomenon. A series of tests have been carried out using roasting - grinding - magnetic separation - leaching technologies to remove the phosphorus from this current concentrate. In the first stage, several tests were performed at pilot scale under the same conditions as described in some publications. The achieved results were similar to those from previous tests at laboratory scale. In the second stage, new test conditions were investigated in laboratory scale in order to achieve better result and to reduce the operational cost.

Aug 1, 2018

Detailed investigation was carried out on the dephosphorization of a number of phosphorus-rich manganese or samples of India by leaching with dilute sulphuric acid. Various process parameters like concentration of acid, liquid-solid ratio, temperature of leaching, time of leaching, and particle size of the ore were studied in detail for the three samples of manganese ore from central India, and optimum values were worked out on a laboratory scale. Preliminary studies show that certain ores which are not easily amemlible to appreciable dephosphorization by leaching with dilute sulphuric acid can be made amenable by :roasting to 700-900°C before leaching.

Jan 1, 1974

By Steve T. Laflin

Since the beginning of the nuclear era, there has never been a commercial solution for the large quantities of depleted uranium hexafluoride generated from uranium enrichment. In the United States alone, there is already in excess of 1.6 billion pounds of DUF6 currently stored. INIS is constructing a commercial uranium processing and fluorine extraction facility. The INIS facility will convert depleted uranium hexafluoride and use it as feed material for the patented Fluorine Extraction Process to produce high purity fluoride gases and anhydrous hydrofluoric acid. The project will provide an environmentally friendly and commercially viable solution for DUF6 tails management.

Aug 1, 2010

By F. W. Mueller

It seems to be a matter of general understnading that title extraction or use of ground water may not be used as the basis of a depletion deduction under the United States Revenue Code And indeed, I have been unable to find any precedent upon which to base such a deduction. It is for this reason that the Shurbet case, which is the subject of my discussion and is now before the Court, may well become a precedent as authority for the allowance or disallowance of a depletion deduction for income purposes. It is well known that the law recognized that capital is consumed in the process of extracting minerals, oil and has, other natural deposits, and timber (underscoring supplied). This exhaustion, or depletion, is likened to the using up of raw materials in manufacturing. The law, therefore, provides a deduction for depletion which is intended as compensation for the exhaustion of assets consumed in the production of income through severance of minerals, oil and gas, other natural deposits, and timber.

Jan 1, 1962

By Chandler Morse

RENEWABLE VS. NONRENEWABLE NATURAL RESOURCES Nonrenewable resources, such as minerals, are the inevitable center of attention in discussions of depletion and exhaustion. Nevertheless, it may well be proper to regard some nonrenewable resources as not subject to exhaustion, and renewable resources may sometimes be treated as if they were finite stocks. Thus, the availability of nonrenewable resources is not and probably never will be known completely Chap. 2.5A, and therefore is not subject to firm predictions concerning exhaustibility. Moreover, because exploration and discovery are more or less continuous processes it is often appropriate to regard mineral supplies as flows, and to treat the estimated reserves as working capital, an inventory, continually depleted by use and augmented by discoveries.23 The aggregate economically exploitable stocks of a given mineral are seldom estimated (or estimatable) with precision, as Chap. 2.5A shows, and even when they are, forecasts concerning years of remaining life can be and often are falsified by changes in one or more of the multidimensional conditions of supply and demand; or the productive services formerly derived from an exhausted stock may continue to provided without material impairment by one or more substitutes b Conversely, the renewable resources are all subject to depletion when the rate of use exceeds the natural or induced rate of replenishment, and cases of exhaustion or near exhaustion, as through soil erosion, overcuttmg of forest lands, and overfishing, are rather common c Where exhaustion is a clear possibility the resource may either be exploited on a consciously adopted "sustainable yield" basis or be treated as an exhausting asset." In some cases, conscious treatment

Jan 1, 1976

In subterranean mining operations, access to communication networks deep underground is critical for transporting data, voice and video, and other supporting applications that are essential for efficient and safe operations. Whether accessing sophisticated ERP or maintenance management systems, engaging in fleet management, video surveillance, or access control, or protecting miners with wireless locator systems, these networks serve as a literal lifeline between workers deep within mines and surface operations. For this, mining networks require more than permanently installed network cabling, it also requires unique deployable systems designed for quick installation, extension and even relocation as the active mine site area moves, or equipment is moved in and out.

Mar 1, 2014

By Emerson Sena Balbino, Emylle Alves Leitão, Gabriel Arthur Guieiro, Lucas van Melis

The deployment of autonomous haulage system causes several impacts in mining production chain, being necessary an appropriate change management policy, crucial to observe and gather all the benefits brought by the technology. The change management is also necessary to guarantee the adaptability of the organization in the long term. This paper briefly presents the technology deployed in the autonomous trucks at Vale's iron ore Brucutu mine, the changes that the operation team faces in the adoption of autonomous technology and the required training path to develop new procedures to deal with the sensitivity of the autonomous haulage system, besides the new operational dynamics from a process point of view, with safer, more consistent and more productive operations.

Oct 3, 2019

By Baafi EY, Sun Y, Tague I

Field trials at three New South Wales and one Queensland coal mines were carried out to gather data on oxygen "run out" times of Self-Contained Self Rescuers (SCSRs), time taken to escape from the mine, distances travelled and the average heart rate of subjects wearing SCSRs. The study has led to a method of predicting the duration of oxygen supply from a SCSR as a function of the wearer's body weight, physical fitness and the prevailing environmental conditions. Escapeway design, planning for emergencies, familiarity with SCSRs and experiential escape training are critical to control panic and maximise the likelihood of survival of a person attempting to escape in an emergency involving fire or explosion.

Jan 1, 1998

By John Durkin, Steven Wirch, Fred N. Kissell, Steven Ruggieri

The Bureau of Mines has developed two expert systems to give advice on coal mine dust control, one for continuous miner sections, and another for longwalls. Prototype versions have been evaluated by coal operators and MSHA. Both systems query the user as to the nature and extent of the dust control problem. Typical questions asked deal with matters such as cutting sequence, current dust standards and characteristics of current dust control techniques. Advice given by the system generally does not focus on a single issue, but may suggest a variety of approaches consistent with the ability of the operator to practically implement what is suggested. Both were written using expert system development software called Insight 2+. The advantages of Insight 2+ for the user are: low cost, IBM-PC compatibility, and the fact that little prior experience with computers is required. For the developer, Insight offers an easy to use production rule language and goal driven structure as well as a wide variety of capabilities.

Jan 1, 1987