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By D. X. Chen

Comprehensive utilization of the copper associated with the complex lead and zinc sulphide ore is a recognized and difficult technical issue in ore dressing field. Qi Baoshan lead-zinc mine is a typical complex copper-lead-zinc polymetallic ore deposit and difficult to process. The application of the. traditional process is not able to make the substantive progress. According to its mineralogical characteristics, the association of copper minerals with lead minerals is very close, and their particle sizes are very fine, and the copper and lead minerals are partially oxidized. Based on the laboratory tests and comparison between different process flowsheets, preferential flotation of copper minerals, being suitable for this ore, was chosen to recover copper. The separation of copper from lead applies the following technology: regrinding middlings with cyclones to classify, which improves copper lead mineral liberation, and increases copper and lead recovery; using new high-efficient collector with good selectivity, which is able to float copper minerals; and non-toxic combined depressant which depresses lead minerals. The above technical innovation, optimizing the process flowsheet, overcoming the complex traditional process flow with high production cost, obtained good technical and economic indicator. The difficult technical problem of copper lead separation was solved smoothly. After successful performance of the bench-scale experiment, commercial-scale test was carried out. In industrial trial, a copper concentrate containing Cu18.60 %, Pb7.40 % and Zn2.50 % was obtained with copper recovery of 58.49%, lead concentrate quality improved largely. The process opened up an unique path for the comprehensive recovery of Cu from similar lead and zinc non-ferrous metals mineral to comprehensively recover copper.

Jan 1, 2014

This paper firstly reviews the requirements for container and hopper design for reliable discharge. Discussion is then directed to the evaluation of the consolidation stresses acting in both in both the cylinder and hopper sections during both initial and flow conditions. Here the vast difference, especially in vicinity of the bin outlet, between the initial or filling and flow conditions is highlighted. This vast difference has major design and operation implications. A further major implication is that all bulk solids must dilate to flow. The opportunity to simultaneously attain reliable discharge and partial moisture removal is also examined.The selection of design parameters to maximise the consolidation stresses in both the cylindrical and hopper sections is detailed. In regard to the latter, it is recommended fine coal bins be discharged using low friction lined transition hoppers with large outlet spans. Such outlets will discharge fine coal in a relatively compacted state. This compaction state should exhibit minimum water retention and short term moisture uptake.

Jan 1, 1998

Research workers From the Bureau of Mines and industry met with other government and industry representatives in Pittsburgh, Pa., on January 22, 1975, to discuss the results of research under the Bureau of Mines Noise Control Program. The program, aimed at reducing noise in mines, is functionally divided into three major areas: Instrumentation, personal protection, and noise abatement. This proceedings contains the opening remarks to the seminar and seven technical presentations based on various aspects of noise abatement and control.

Jan 1, 1975

By G. K. Quainoo

In the automotive industry, the awareness to meet Corporate Average Fuel Efficiency (CAFE) standards has evolved the need to reduce vehicular weight in new automobile designs, with the overall goal of reducing gas emissions into the atmosphere (Kyoto protocol), One efficient method has been to use lighter materials such as aluminum in outer body panels, Heat treatable AA6111 is one of the materials employed due to its unique combination of formability, paint bake strengthening and superior corrosion resistance characteristics, Researchers have applied various thermo-mechanical processes on 6000 series aluminum alloys and have found an improvement in the mechanical properties of these alloys, For a formed and painted automobile panel, the final mechanical properties involve a combination of strength components arising from cold work, strain aging and precipitation minus recovery. In this study, the evolution of microstructure resulting from the interaction of cold work and precipitation in AA6111 has been studied by means of transmission electron microscopy (TEM) after subjecting samples to various heat treatments, tensile testing and differential scanning calorimetry (DSC), This has been done to understand the evolution of microstructure and its influence on the properties of the alloy, The results show a considerable improvement in strength with a corresponding increase in strengthening precipitates with increasing level of cold work in the alloy. DSC results following the application of various levels of cold work also show acceleration in the precipitate phase formation, as precipitates are observed to form at lower temperatures, with increasing level of cold work/

Jan 1, 2005

By S. Afrouz, C. Keles, W. R. Reed, E. Sarver, T. Akinseye, A. Greth, L. Pan, F. Animah

Among underground coal miners, roof bolter operators are generally considered to have some of the highest risks for hazardous respirable dust exposure. This is because bolting requires drilling into roof strata that can often be a source of silica and silicate dust, which are associated with occupational lung diseases. However, little is known about the variability of dust characteristics (e.g., mineralogy constituents, particle size) in the vicinity of the bolter—or when specific dust controls are applied. As part of a prior NIOSH study, respirable dust samples were collected during several different events in standardized locations around an active roof bolter, and personal samples were also collected from the operator during the cleanout of the bolter’s dust collection system when it was equipped with a novel wet dust box versus a traditional dry box. Those samples were made available for follow-up analysis by scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM–EDX), as well as direct-on-filter Fourier transform infrared spectroscopy (FTIR). Results showed variability in dust constituents and particle sizes at locations around the roof bolter, and indicated some event-to-event differences in dust sources. Additionally, compared to the dry dust box, the wet dust box appeared to reduce (by 41–82%) the relative silica and silicate content in the respirable dust to which the operator was exposed during cleanout. Furthermore, an inter-laboratory comparison demonstrated the reproducibility of a standardized direct-on-filter FTIR method for estimating quartz mass (i.e., the predominant form of crystalline silica) in respirable coal mine dust samples. However, for constituent analysis by SEM–EDX, differences observed between results from two independent labs indicate that standardization of the analytical protocol is necessary to enable comparability of results.

Jan 5, 2024

By Holt, Grover J.

PRIOR to :1937 any discussion of mining and transportation in the iron mines of Minnesota would have been limited largely to conventional methods which have been used for years in the iron ore industry. Today, however, an inspection trip to the crest of almost any open pit on the ranges will re- veal great progress underground mining and the transportation of underground ore have also developed rapidly and if and when underground mining of iron ore again becomes generally economically feasible; these mining methods will probably witness a transformation equal to that which has taken place in the open pits.

Jan 1, 1941

By S Nowosad, O Langefeld

The mining industry has undergone a profound and transformative shift in recent years, driven by the rapid advancement of emerging technologies such as automation, digitalisation, and electrification. These technological innovations have not only revolutionised operational efficiency and productivity but have also introduced an imperative need for new and innovative approaches to conducting mining activities. Specifically, the mines of the future face a new series of complex challenges when planning and developing greenfield or brownfield mining projects in the 21st century. These challenges include greater operational depths, higher seismicity levels, higher rock temperatures, increased environmental constraints and sustainability requirements, a higher degree of interoperability, lack of skilled workforce, and the need for sustainable and eco-friendly mining practices. Consequently, there is an essential need to formulate novel strategies and robust planning methodologies that re-evaluate how mines are planned, executed, and managed, from the early exploration stages to the post-mining era and the consequent uses of mine sites. This research focuses on identifying the factors influencing the implementation of modern technologies, such as autonomous machinery in mining operations, and their impact on mining method selection and longterm mine planning. The findings underscore a crucial need for a paradigm shift in how mines are planned and developed, going beyond mining method selection, which primarily focuses on geological and economic factors, and must evolve to incorporate the multifaceted implications of modern mining operations.

Sep 1, 2024

By Lv Guozhi, Ren Xiaodong, Liu Yan, Dou Zhihe

"This paper investigated a new desulfurizer, dolomite and ferrosilicon. Magnesium vapor produced by silicothermic reduction of dolomite and ferrosilicon in an immersion tube of molten iron was injected into the molten iron by carrier gas through the underpunch of the tube and desulfurization reaction occurred. In order to explore the desulfurization process of molten iron by the new desulfurizer, the thermodynamics, and experiments of magnesium vapor production and desulfurization have been studied. Through thermodynamic calculation, the reaction temperature of magnesium vapor production by 75ferrosilicon and light-burned dolomite is 1838K in the standard state and decreased with the decreasing partial pressure of magnesium vapor, PMg· When PMg=25kPa, the reaction happens at 1673K. From experiments of magnesium vapor production, reduction efficiency of Mg vapor is about 60 % in 15 minutes at 1673K. From hot metal experiments, the desulfurization efficiency is 89.35%, and the lowest sulfur concentration after desulfurization is 46ppm.IntroductionPretreatment desulfurization of hot metal has become a necessary step in modem optimizing steelmaking process for its cheap cost, which can not only liberate of blast furnace productivity and reduce the burden of produce steel, but also effectively improve overall economic efficiency of the iron and steel system[l-ZJ_ At present, injection magnesium particle is one of the two main methods of desulphurization in hot metal owing to its strong affinity for sulphur, low amount of slag produced, low iron loss in slag skimming and low equipment investment[3l. However, there are still some insufficiencies on the hot iron pretreatment with magnesium particles at present[4-5l"

Jan 1, 2013

By Margaret Armstrong

The increasing cost of developing new mines and the need to mine more marginal deposits have led mining companies to use more sophisticated estimation methods such as kriging. But until recently, coal mining companies have shown little or no interest in these techniques. However, the stringent quality controls which are now placed on coal have led to a surge in interest in improved estimation methods. This can be seen from the -, number of research projects by private companies and governmental agencies on the application of geostatistics to coal reserve estimation. At present, most of these programs are centered on the problem of estimating the tonnage and the average grade (i.e. ash percent, sulphur content, calorific value, etc.) of the coal in-situ. See, for example, Sabourin (1975), Woods (1976, 1979), Pauncz and Nixon (1979) and Armstrong (1980). These studies show that the established techniques of linear geostatistics can be applied successfully to coal deposits. The study by Woods is particularly interesting because he had access to the actual production figures as well as the initial sample data from the no 2 seam in the Greenside Colliery owned by the Anglo-American Corporation. He showed that the estimates obtained by kriging were consistently closer to the actual production figures than those given by three other estimation methods. This confirms the superiority of kriging as a method of estimating block values for coal. Another advantage of geostatistics is that it can be used to determine the optimal spacing between drill holes. An example of this is given by Armstrong for the coking coal deposit in the Bowen Basin, Australia.

Jan 1, 1981

By D. Paktunc, S. P. du Preez, J. P. Beukes, P. G. van Zyl, A. Jordaan

"The chromium (Cr) content of stainless steel originates from recycled scrap and/or ferrochrome (FeCr), which is produced mainly by the carbothermic reduction of chromite ore. The oxidative sintered pellet production process is one of the most widely applied FeCr processes. The supplier of this technology specifies that recycling of chromite-containing dust collected from the pellet sintering off-gas and fines screened out from the sintered pellets (collectively referred to as pre-oxidized chromite fines) should be limited to a maximum of 4 wt% of the total pellet composition. However, the results presented in this paper suggest that recycling of such fines up to a limit of 32 wt% of the total pellet composition may improve the compressive and abrasion strengths of the cured pellet. In addition, electron microprobe and quantitative X-ray diffraction (XRD) analyses demonstrate that chromite grains present in the pre-oxidized chromite fines consist, at least partially, of crystalline phases/compounds that will improve the metallurgical efficiency and specific electricity consumption (i.e. MWh/ton FeCr produced) of the smelting process. Introduction Stainless steel is a vital modern-day alloy that is well-known for its corrosion resistance, which is mainly due to the inclusion of chromium (Cr) (ICDA, 2013). Stainless steel is mostly produced from recycled scrap and ferrochrome (FeCr), a relatively crude alloy of Cr and iron (Fe). FeCr is predominantly produced by the carbothermic reduction of chromite, a mineral belonging to the spinel group characterized by the unit formula [(Mg,Fe2+)(Al,Cr,Fe3+)2O4] (Haggerty, 1991; Paktunc and Cabri, 1995; Tathavakar, Antony, and Jha, 2005). Although Cr can occur in 82 different minerals, chromite is the only source of new Cr units that can be exploited in commercial volumes (Motzer and Engineers, 2004). Approximately 95% of mined chromite is used in the production of various FeCr grades, of which high-carbon and charge grade FeCr are the most common (ICDA, 2013)."

Feb 1, 2019

By J. P. Walker

"INTRODUCTION Sponge iron has been made commercially since 1912 at a Swedish ceramic plant; and the product, known as Swedish disk-type nagger sponge iron, has an excellent reputation as a superior furnace feed wherever high-grade steels are made.The general procedure for making brickyard sponge iron was described frequent in Swedish technical journals before 1932 and at that time consisted in filling clay refractory containers, called saggers, with iron ore plus the necessary quantity of solid reducing agent and then firing in an ordinary ceramic kiln. Two types of sponge iron were made in this way: (1) An inferior, high-sulfur product obtained by mixing the ore and solid reducing agent; and (2) a high-grade, low-sulfur product made by filling the sagger with alternete layers of unmixed ore and reducer, yielding sintered disks of metallic iron particles.Swedish disk-type sponge iron of interest to the steel industry because it has a very low sulfur content, even when made by the use of low-grade, high-sulfur coals for reducing and firing. The Swedish product also contains little siliceous gangue residue and is almost phos¬phorus-free. To those features must be added the high metallic-iron content -90 to 96 percent - and freedom from even small amounts of the metals that are undesirable in steel making.The details essential for successful operation of this procedure are not known, especially as regards improvements said to have been made since 19;2. The Bureau of Mines therefore decided to determine some of these missing details, and this report records the results of the first set of experiments on the manufacture of brickyard or sagger sponge iron."

Sep 1, 1945

By H. H. Stoek

(Wilkes-Barre Meeting, June, 1911.) THE origin of the Mine-Rescue Service of the State of Illinois can be traced to two distinct sources, the work of the Rescue Station at Urbana and the Cherry disaster. During the early part of the year 1909, the Technologic Branch of the U. S. Geological Survey, now the Bureau of Mines, in connection with the Illinois Geological Survey and the College of Engineering of the University of Illinois, established at the University of Illinois, in Urbana, a branch rescue-station to supplement the work of the Pittsburg station of the Geological Survey. As a result of the work of training at the station in Urbana by R. Y. Williams, mining engineer, and James Webb, foreman of the Bureau of Mines, and the use of the helmets at several mine-accidents in the State of Illinois, . the people of the State were somewhat familiar with oxygen-helmets when the Cherry disaster occurred, in November, 1910. The oxygen-helmets were successfully used in connection with that disaster, and upon the recommendation of the Illinois Mining Investigation Commission, the Legislature of the State, assembled in special session during the winter of 1910, passed a bill appropriating $75,000 for the erection and maintenance of three rescue-stations, stipulating that they should be located in the northern, central, and southern parts of the State. The Act also provided that the stations should be in charge of a Commission of seven, two representing the United Mine Workers of Illinois, two the mine-operators, one the Federal Bureau of Mines, one the State mine-inspectors, and one the Department of Mining Engineering of the University of Illinois. This Commission was called together by the Governor of the State, Aug. 2, 1910, and since that time three stations have been located, built, and equipped: at La Salle for the northern

Dec 1, 1911

By W. G. Hubler

History The Aldermac mine is situated on the Nipissing Central railway near the ' centre of the township of Boischatel, Quebec, and is about ten miles west of Noranda. Aldermac Mines, Limited, is a subsidiary company of Towagamac Exploration Company. The property was staked by Messrs. Alderson and MacKay and McMartin, during the winter of 1922-23. During October, 1925, a copper discovery was made by K. W. Fritzsche, who was in charge of exploration work at that time, the first trench on this discovery averaging 8 per cent copper over a width of ten feet. This led to the discovery of another body 200 feet to the north, with an average of 3 per cent copper over fifteen feet in width. A magnetic survey was then carried out which led to the location of the large pyrite ore-bodies which have been developed in the past few years. Development work was carried on to a depth of 1,125 feet, and approximately three million tons of massive pyrite ore was indicated. Extensive metallurgical tests were conducted in the laboratories of the Mines Branch of the Department of Mines at Ottawa to determine the proper metallurgical treatment and the economic possibilities of the ore. Owing to the comparatively low copper content, and the uncertainty of the copper market, it was doubtful if the mine could be profitably operated for the production of copper alone. Messrs. Alderson & MacKay, however, realized the possibility of utilizing the large tonnage of pyrite as a substitute for native sulphur, 'which in past years has been imported into .Canada for the manufacture of acid and sulphate pulp in paper mills. They therefore organized the Sulphite Research Corporation with the object of developing an economical process of utilizing the pyrite.

Jan 1, 1932

By William E. Young

There are many large rhodunite-bearing veins containing manganese in the Eureka-Animas Forks area of the San Juan Mountains in Colorado. The Sunnyside vein is the largest known vein in the area. As observed on the surface, the vein is mineralized over 8,000 feet and attains a maximum width of 200 feet. The average width of the vein and its branches and ramifications is 58 feet in the area that was mapped in detail. The weighted-average analysis of surface and underground samples from the northeastern extension of the Sunnyside vein is 8 percent manganese. Most other known veins in the area have a similar manganese content. The Hidden Treasure vein lies southeast of the Sunnyside-No Name-Mastadon vein. The weighted average of the analyses of surface and underground samples from this vein is 13 percent manganese. Exposures of the Scotia-Silver Chord vein are visible over a strike length of 4,000 feet on Treasure Mountain. Diamond-drill holes show that the vein contains 10 percent or more manganese to a depth of 400 feet. The vein has an average width of 28 feet. The Independence vein is exposed on the surface for a distance of 600 feet and has an average width of 6 feet. Three cut samples taken across the vein had an average content of 20.7 percent manganese. Sampling of the outcrops of eight veins in the Placer Gulch area also indicates manganese. Numerous other veins cropping out in the surrounding area are similar to the outcrop of the. Sunnyside vein system mineralogically and are worth investigating.

Jan 1, 1966

By Harry W. Campbell

During 1983, the U.S. Bureau of Mines conducted a mineral survey of 19,700 acres that included the Fish Creek Mountains WSA (Wilderness Study Area), 15 miles southwest of the Salton Sea. Two United States Gypsum Co. claim groups in the WSA have more than .20 million tons of inferred gypsum reserves. These high-grade, surface and near-surface gypsum deposits are an extension of a gypsum bed that has been mined continuously since 1922. The Waters prospect in the central part of the WSA has large quantities of limestone suitable for many commercial uses. Sand and gravel is plentiful in the WSA in alluvial fan and ancient shore-line deposits. Limestone and alluvial deposits are not economic because similar material is closer to potential markets. No evidence of energy minerals or geothermal resources was identified in the WSA. A portion of the eastern Fish Creek Mountains WSA is leased for oil and gas exploration. United States Gypsum Co. holds eighteen unpatented placer claims in the northwestern part of the WSA. No other mining claims or mineral leases were identified in the study area. No mineral production is known from within the WSA.

Jan 1, 1986

By H. H. Kellogg

A model of the slag-fuming process for recovery of zinc oxide fume from lead blast furnace slags, adapted to solution by a digital computer, is presented. The model incorporates the variaticm with time of the following: the fuming of zinc and lead, the change in the ferrous-ferric ratio in the slag, the transfer of sulfur to and from the slag, the temperature of the liquid slag, the temperature of the gases and fume which exit to the flue, the heat losses to the water jackets, and the amount of frozen slag on the water jackets. The assumptions which underlie the model-some of which are but crude approximations—are discussed. Despite some obvious shortcomings, the model simulates faithfully many of the important features of practical slag-fuming operations. The behavior of the model is compared with the operation of the American Smelting and Refining Co. fumzace at El Paso, Tex. The model is used to predict the effects on performance of changes in the coal rate, the temperature of the secondary air, and the composition of the coal. THE fuming of lead blast furnace slag for recovery of zinc oxide is standard practice today, and it has been the subject of several previous attempts at mathematical process analysis.'-' The mathematical process model described in this paper incorporates many of the features from the earlier studies, but it is a far more complete and realistic representation of the commercial process in that the following additional features have been included: the fuming of lead as well as zinc; the transfer of sulfur between slag and gas; the addition of slag feed in batches, over a period of time; tapping of the final slag over a period of time; the change of slag temperature with time. The additional features of the present model add greatly to the mathematical complexity, but this difficulty has been obviated by programming the model for solution by a digital computer. The IBM 7094 computer solves the model for one operating cycle of the fuming furnace in less than 1 min. It is doubtful if the same calculations could be completed with the aid of a desk calculator in less than a month. The computer program, written in the Fortran IV language, is too lengthy for presentation here.* Instead, this paper As shown in the sections which follow, it does simulate with remarkable faithfulness most of the known behavior of the industrial process. On the other hand, the model contains several gross simplifications of both the chemistry and heat balance, necessitated by the lack of more exact knowledge. In addition to these known weaknesses, it is not unlikely that those more intimately acquainted with industrial practice than the author will find other additions to or modifications of the model which will improve its utility and reliability. CHEMISTRY In brief outline, the present model treats the fuming furnace as two units, A and B, in series. In A the batch of slag reacts with the continuous stream of air (primary and secondary) and fuel injected at the tuyeres, to produce a stream of hot, reduced gases containing zinc vapor. The zinc content of both the slag and the product gas changes with time because of the batch nature of the process. Unit A is called the "lower furnace" in this paper; physically, it is considered to be that part of the fuming furnace which lies below the charge port. In B, the "upper furnace", the product gas from A is burned with the stream of "tertiary" air, to produce zinc oxide fume. The performance of B also depends on time because of the time dependence inherited from the product gas of A. The rate behavior in the lower furnace determines the important features of the process—the rate of elimination of zinc and lead from the slag, and the amount of fuel required for this purpose. Bell, Turner, and peters' published the first useful model of the lower furnace. They employed the assumption that, at any instant of time, the slag and reduced gas reach a state of equilibrium, according to the reactions: They cited only indirect evidence in support of their assumption of slag-gas equilibrium, yet several more recent laboratory studies of the activity of zinc oxide in slags4-8 have produced evidence which supports their view. On first acquaintance it seems unlikely that a high-output "rate" process like slag fuming would even approach an equilibrium state. The author, in an earlier study,' established, however, that the gas-slag interface in a fuming furnace was capable of such high mass-transfer rates that a close approach to equilibrium between gas and slag was quite probable. In devising the present model it was decided to assume a state of equilibrium between slag and gas at the outset, and then to modify this assumption as necessary in order to make the model agree with the be -havior of the actual process. Up to this time the assumption remains a part of the model, since no behavior

Jan 1, 1968

By J. Murdoch Mackenzie

Two commercial nickel solvent extraction plants treating laterite leach solutions and using LIX®84-I have been operated in Australia. These circuits employ similar extraction chemistry but differ in their leaching and stripping operations. An alternative process involving elements of both can be conceived. The preparation of the feed solution to solvent extraction plays an important role in nickel extraction using LIX®84-I and the special features of manganese removal and cobalt oxidation in the preparation of the PLS are discussed. This paper compares these three circuit configurations with special reference to the extraction and reductive stripping of cobalt, the transfer of zinc and copper to the strip aqueous, ammonia transfer and sulfur transfer. The potential degradation of the organic and remediation using re-oximation is discussed. Keywords: Nickel, Solvent Extraction, Oxime

Jan 1, 2004

By Moore, Richard B

PROBABLY no other metal excites as much interest, among both scientific men and the general public, as radium. This is due partly to the high cost of radium salts and partly to the peculiar properties of the element. Since radium-bearing ores were discovered in the United States, the interest of American scientific men has been stimulated and, at the present time, more radium is extracted and refined in this country than in all the rest of the world together. HISTORY The property of radioactivity was discovered, partly by accident, by Henri Becquerel, the French physicist, in 1896. He was experimenting with certain fluorescent substances in order to find, if possible, a connection between fluorescence and the recently discovered Y-rays. Among other chemicals which possess the property of fluorescence, he was using

Jan 8, 1918

By S Wan, F Zhang, J You, K Tang, X Tang, C Bessada, A Canizarès, Q Zhang, L Lu

Microstructure of CaO-SiO2-based glassy samples with various Al2O3 contents were examined quantitatively by Raman spectroscopy and 27Al MAS NMR (magic-angle spinning nuclear magnetic resonance). Sequence of multiple cluster models of aluminosilicate system modified with Ca2+ and Na+ cations have been designed, and Raman spectra simulation were carried out after geometric optimisation by quantum chemistry (QC) ab initio calculation. The functional relationship between Raman scattering cross-section (RSCS) and stress index of silicon-oxygen tetrahedron (SIT) for aluminosilicates was established, which was applied to the calibration of experimental Raman spectra. Some five-fold coordinated aluminium (AlV, around 5 per cent) and less than 2 per cent sixfold coordinated aluminium (AlVI) were detected by 27Al MAS NMR, while most of aluminium remained in tetrahedral sites (AlIV). The hyperfine quantitative results of Raman spectroscopy and NMR showed a gradually production of AlIV with addition of Al2O3, along with the significant adjustment of Qi species distribution, in which Q1, Q2 reduced and fully polymerised Q4 increased while Q3 showed a non-monotonic variation and obtained the maximum at Al2O3 = 18 mol per cent. Furthermore, the effects of aluminium to bridging oxygen bond types (T-Ob, T = Si, Al) and the degree of polymerisation were also discussed in detail. The evolution of microstructure and its correlation with the viscosity of CaO-SiO2 based melts, incorporating various Al2O3 additives, have been investigated by employing in situ high temperature Raman spectroscopy at 1823 K and viscosity model. These structural features related to composition are essential theoretic foundation to understand their properties. The average Qi evolution culminates in an overall enhancement of the degree of polymerisation. Viscosity was determined utilising a rigorously selected viscosity model, elucidating a consistent upward trajectory as Al2O3 content is incrementally added. Furthermore, a quantitative analysis of the relationship between viscosity and structure was conducted based on the average number of non-bridging oxygen per network-forming tetrahedron (NBO/T). It provides valuable insights for examining and predicting viscosity behaviour of aluminosilicate systems.

Aug 21, 2024

By Alberto Pesamosca

The present work analyzes the latest results achieved in scrap based EAFs in terms of application of chemical energy, starting from the observation that the general trend is a reduction of oxygen utilization. Consequently a review is needed about criteria for evaluation of melting process efficiency and equipment design. If from one side the maximization of productivity remains one of the major goals, from the other side some aspects of present market situation, included price of raw materials, are requiring the maximization of process yield. Based on achieved performance figures of selected plants and theoretical considerations, the effect of chemical energy input intensity is analyzed focusing on transformation cost, productivity and total energy input. The effect of present practices with lower oxygen utilization is considered also in terms of global CO2 emissions. Finally, the latest Danieli concepts and technological tools for optimization of chemical input are presented.

Aug 17, 2017