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By V. M. Lsoitko

Statistical methods of technological mineralogy are used to model processing flowsheets in order to improve ore dressing efficiencies. The procedure involves determining geological and mineralogical characteristics of ores, classifying ore types and metallurgical procedures, and developing computer programs to interpret essential mineralogical parameters from on-stream analysis data. The on-stream analysis data include magnetism, radioactivity, luminescence and assays. The data are interpreted by computer and appropriate adjustments are made automatically in the plant.

Jan 1, 1989

By Pengcheng Li, Wei-Tong Du, Yu Wang, Gang Wen

Carbon dioxide could be utilized as a weak oxidant and a kind of coolant to oxidize elements, meanwhile, helping control the temperature during the converter vanadium extraction process. However, the optimum content of CO2 and the cooling effect of CO2 at low content have not been reported. In this study, experimental research based on the influence of different CO2 contents from 0% to 25% injected to the vanadium-containing hot metal was carried out, as well as contrast experiments of O2-N2 mixed blowing. The results indicated that the optimum content of CO2 was 15%. Under the optimum condition, the oxidation of [C] was the lowest and the oxidation rate of [V] was 96.9%, while the temperature was also lower than the O2-N2 mixed blowing. This paper provide a potential property for utilizing CO2 during the converter vanadium extraction process.

Jan 1, 2016

By J. Rajek

The novel multi-component, multi-particle, multi-phase precipitation model developed recently is used to predict the precipitation kinetics in complex 9-12% Cr steels investigated within the European COST 522 project. These steels are used for tubes, pipes, casings and rotors in USC (ultra super critical) steam power plants for the 21st century. In the computer simulations, the evolution of the precipitate microstructure is monitored over the entire production heat treatment starting with the casting process, including austenizing, several annealing treatments and in-service conditions. The main interest lies on the concurrent growth and coarsening interaction of different types of precipitates. Keywords: Precipitation kinetics, heat treatment, power plant steels, simulation

Jan 1, 2003

By Sheng Dai, Yuan Lee, Haiming Xiao, J. P. Young

"There are numerous analytical applications of scatter-emission and/or absorption spectroscopy applied to liquids and solids in the temperature range of 0 to 350°C. In this paper an all-silica fiberoptic probe is described which is useful for spectral analyses from 0 to 1600 K and can be used in harsh chemical environments. The probe has been used for Raman spectral analyses of many molten salt and solid material systems to 1000°C. It has applications for such studies at higher temperature ranges. The instrumentation required along with the demonstrated and proposed applications of the all-silica probe are presented and discussed.IntroductionThere are many kinds of scatter-emission spectroscopies that are of value for analytical measurements. Fluorescence, reflectance, arc or spark emission are descriptors for some of these. Raman scatter spectroscopy is also quite a useful technique for analytical measurements.In Figure 1, we give a simplified explanation of the Raman effect. If one shines monochromatic light into a sample, light may be absorbed, exciting the sample to some virtual state. We know from experience that almost all of the light is re-emitted in the same wavelength range. This is called Rayleigh or Mei scattering and is designated in the figure by the arrows in both examples that point up and down from the same lower energy state. A very small percentage (the order of 10-4%) of the monochromatic light is re-emitted leaving the sample at a vibrationally-excited state. Thus, this light is at a distinctly lower energy compared to the exciting radiation. This is called a Stokes shift and is represented in the left-hand example by an arrow descending to a more energetic vibrational state. If the sample is not at a temperature of absolute zero, some of this vibrationally excited state will be thermally populated. That portion of the sample still absorbs and re-emits exciting radiation as Rayleigh scattered light, but a small percentage of the exciting light is re-emitted as the sample relaxes to the lower vibrational state. The energy of this light is of higher energy and is called an anti-Stokes shift, depicted in the example to the right. Notice that the energy separation of the Stokes or anti-Stokes shifted emission from that of the exciting radiation is the same, and expressed in ~cm-I. The intensity of either shifted emission is a function of the population of the vibrational energy states; therefore, the ratio of the intensity of Stokes to anti-Stokes signal varies with absolute temperature. We will come back to this point later."

Jan 1, 1997

By Sedef Pinar Basag, Onuralp Yucel, Ahmet Turan

Niederschlag process is commonly used to produce metallic antimony. The process is a metallothermic process which is conducted in one step for metallic antimony production. Using this method Sb2S3 is mixed with coal and metallic iron and subjected to reduction. During heating, antimony sulfide is decomposed and sulphur combines with iron to form the matte phase. Metallic antimony is collected at the bottom of the crucible. In this study, evaluation of Sb2S3 concentrate, extracted and obtained from West Anatolian Region of Turkey was investigated by using Niederschlag process. The reductant stoichiometry, reduction temperature and duration were carried out in the experiments. Chemical analysis methods by using atomic absorption spectrometry (AAS) and X-ray diffraction spectrometry (XRD) techniques were used for the characterization of the concentrate, metallic nuggets and matte phases.

Jan 1, 2016

By Uchil Jayagopal, M. Krishna, P .. V. Krilpakara, S. Manjunath

"There have been a pioneering efforts over the last forty years in the development of metal matrix composites (MMCs) as a new engineering materials, having improved properties, light weight characteristics and competitive costs compared to traditional materials. Following recent advancements in casting technology and the use of melt stirring device by foundries, discontinuously reinforced MMCs where prominent alloys are reinforced with particulates or short fibres and the being employed ·in the production of castings targeted for automotive and aerospace application.The ZA-27 alloy has a high strength compared to zinc or alluminium alloys with a lower melting temperature. The main objective of the present research is to study the effect of quartz particles on the mechanical behaviour of ZA-27 alloy composites. The results showed that the ultimate tensile strength, hardness, Young's modulus of the composite gradually increased with increase in the weight percentage of the quartz reinforcement. However overall ductility decreased with an increase in quartz reinforcementIntroductionMetal matrix composite (MMCs) offer outstanding benefits as they combine metallic properties with ceramic properties there by yielding improved physical and mechanical properties.1Among the various type of MMCs particulate reinforced composite are the most versatile and economical2. By suitable choice of metal matrix and particulate system a wide range of properties combination can be obtained such as strength, modulus, fiiction.al resistance, tribological performance and machinability. These composites are capable of replacing conventional alloys in a considerable range of applications. They also offer significant saving in energy and resources"

Jan 1, 2000

By Nagy El-Kaddah

"One of the emerging technologies for the production of ultra-clean metals is electromagnetic filtration. The theory and the mechanism of electromagnetic separation of inclusions from molten metal are briefly reviewed along with basic electromagnetic separation systems. This paper focuses on inclusion removal in the induced current separators, with specific reference to a new separator developed at the University of Alabama. A simple analytical model is presented for the analysis of particle separation in such a system. The role of the applied magnetic field on inclusion removal will be discussed. It is shown that particle velocity increases exponentially with increasing magnetic field strength. At moderate field strengths, the velocity of 50 to 100 u. inclusions· are an order of magnitude larger than those achieved by buoyancy. The separator developed at the University of Alabama is described together with experimental results of laboratory and large scale experiments on purification of molten aluminum. These results demonstrate the capability of the system for producing super-clean metals.IntroductionThe nature of extraction, refining and processing of metals is such that oxides and other non-metallic particles will always be present. This is due to the highly reactive nature of metals with oxygen and other non-metallic elements. The presence of these type inclusions in metals, even in minute amounts, can seriously flaw the reliability and performance of the final product. They not only reduce the strength and the stiffness of the metal/1/, they are the reason behind many of manufacturing defects such as porosity in castings, surface and internal cracks in continuously cast ingots and rolled products, etc., which act to cause premature failure of manufactured parts. In fact, for critical applications such as turbine blades, there is virtually no tolerance for inclusions above ten microns in size /2/. Therefore, removal of inclusions from the liquid metal is an essential processing step.The demand for cleaner metals has brought major changes in the technology and practice of metal refining and casting. Inclusion removal from the melt is currently achieved by passing the melt through a series of melt treatment systems, including induction stirring furnaces, argon-stirred ladle, and ceramic foam and deep-bed filters /3,4/. These systems are generally capable of removing all inclusion particles above 50 microns in diameter, which meets current cleanliness requirements for most applications. However, they may not be able to meet the projected cleanliness levels for critical applications due to kinetic and operational limitations of these systems in removing smaller particles /5/."

Jan 1, 1996

By Jr. Foot

The Bureau of Mines, U.S. Department of the Interior, investigated flotation methods for recovering fluorite and byproduct beryllium from the Fish Creek deposit of Nevada. The preferred method includes (l) fluorite rougher and cleaner flotation, (2) de sliming at 20 micrometers, (3) muscovite flotation, (4) silicate flotation, (5) hypochlorite wash of silicate concentrate, and (6) beryllium rougher and cleaner flotation from the silicate concentrate, Laboratory results showed that over 94 pct of. the fluorite was recovered in a concentrate containing 96 pct CaFz. Beryllium flotation produced .concentrates .containing in excess of 5 pct BeO with recoveries over 70 pct. A 1.00-lb/h continuous flotation unit was constructed to demonstrate this procedure,

Jan 1, 1985

By Alwin Frei, Aldo Steinfeld, Peter G. Loutzenhiser, Enrico Guglielmini

"Using concentrated solar radiation as the energy source of high-temperature process heat, the carbothermal reductions of Al2O3 to Al and SiO2 to Si were examined thermodynamically and demonstrated experimentally at vacuum pressures. Reducing the system pressure favors Al(g) and Si(g) formation, enabling their vacuum distillation and avoiding contamination by carbides and/or oxycarbides. Exploratory experimentation in a solar reactor was performed with mixtures of charcoal with alumina and silica in the ranges of 1300-2000 K and 1997–2263 K, respectively, at 10-3 bar by direct exposure to concentrated thermal radiation. Distilled samples contained up to 19 wt% of Al in Al-Al2O3 mixtures and 79 wt% of Si in Si-SiO2 mixtures. When the reducing agent is derived from a biomass source, the solar-driven carbothermal processes are CO2 neutral.IntroductionMetallurgical extractive processes for producing Al1-2 from Al2O3 and Si3-6 from SiO2 are characterized by their high specific energy consumption and concomitant emissions. Alternatively, concentrated solar energy can be used as a high-temperature heat source to drive the carbothermal reductions and, thus, avoid greenhouse gas emissions and other pollutants derived from fossil-fuel-based processes7-12. When the reducing agent is biomass charcoal, the solar-driven carbothermal reduction is CO2 neutral. The carbothermal reductions of Al2O3 and SiO2 are represented by the simplified overall stoichiometric reactions:"

Jan 1, 2011

By Zhihong Liu

In recent years, the removal of arsenic from different types of high arsenic containing materials produced in nonferrous metallurgical processes have been experimentally studied in the complex materials processing research group from Central South University. These materials include arsenic and antimony bearing flue dust, arsenic sulfide residue and arsenate bearing flue dust. The separation of arsenic from other valuable metals was carried out hydrometallurgically; for each type of arsenic bearing material, different processes have been employed individually to remove the arsenic effectively. In this paper, the flowsheets and typical experimental results have been summarized.

By Shengli Wu, Wei Huang, Xinliang Liu, Kaifa Zhang

The slagging behavior, the phase of primary blast furnace slag and its transformation law of structure for the single furnace burden were studied in this paper. The results showed that the formation of primary slag was controlled by CaO/SiO2, Al2O3 content, MgO content, reducibility, iron content and porosity of the furnace burden. Fayalite (2FeO•SiO2) was easily formed from acid ferrous furnace burden while kirschsteinite (2(Fe,Ca)O•SiO2) was produced from alkaline ferrous furnace burden

Jan 1, 2015

By Yasuo Kudo, Wu, Hayato Sato, Hiroshi Nakazawa, Shouming

"In order to recover copper from a waste nickel condenser powder, bioleaching experiments were carried out using Thiobacillus ferrooxidans in a shaking flask. The content of nickel and copper in the waste nickel condenser powder in this study were 8.0% and 3.5%. X ray analysis showed the peak of barium titanate. In the preliminary study using metal nickel and copper powders , the dissolutions of nickel and especially copper were accelerated with the addition of ferric iron in the bioleaching of nickel and copper powders while not in the absence of ferric iron. Ferric iron oxidizes both metals, and Thiobacillusferrooxidans oxidizes ferrous iron resulting from the oxidation of metals, whereby the dissolutions of metals proceeds. The dissolution rates of nickel and copper increased with increase in the concentration of ferric iron in the bioleaching of the waste nickel condenser powder.1. IntroductionNickel condensers rejected from manufacturing plants are crushed and landfilled. Waste nickel condensers contain nickel and copper and could be considered as nickel and copper ores. Since the capacity of landfills is diminishing, it is required to recycle metals of waste nickel condensers in order to reduce the amount of wastes landfilled. Conventionally, metals in the waste were recovered by dry metallurgy after the incineration.Nickel has been refined by solvent extraction - electrowinning method (SX-EW method). Recently the amount of copper refined by SX-EW method has increased (Takahashi, et al. 1994). This method is cleaner and consumes less energy than conventional methods. Nickel dissolved well in acid solutions, but copper is not. If copper is leached efficiently from a waste nickel condenser powder, SX-EW method will be applied to recover copper from them"

Jan 1, 2000

By Bo Jiang, Jiusan Xiao, Hongmin Zhu, Kai Huang, Shuqiang Jiao

Carbothermal selective reduction of simulative titanium slag and various titanium raw materials were presented and SiO2 was found to be partially reduced, forming a series of Fe-Si alloys during the process. Thermodynamic analysis of the selective reduction between TiO2 and SiO2 was performed using HSC 6.0 software, then a series of equilibrium experiments were designed and presented. The activity of Si reduced from SiO2 was affected by the presence of Fe reduced from FeOx and the generation of Fe-Si alloys, promoting the reduction of SiO2 in the whole process. The results of experiment are in great accordance with the calculated data obtained from thermodynamic analysis.

Jan 1, 2016

By Roberto Parra

The selective reduction smelting of Cu2O in Cu2O-FeOx-SiO2 melts has been studied at laboratory level, using as a feed a dead roasted calcine from a copper concentrate. The purpose of the study was to evaluate the kinetic and mechanisms of the indirect reduction with CO and the direct reduction with graphite from 1260°C to 1350°C. The reduction rate by CO was found to be 10-2 to 10-1 mole Cu2O m-2s-1. The graphite reduction macrokinetics for FeO and. Fe2O3 containing melts, was found to be a first order reaction with respect to the Cu2O concentration, with a kinetic constant of 104 to 10-3 s-1. The reduction rate was not sensitive to temperature nor to stirring, in the range studied. The measured reduction rate is almost one order of magnitude larger than the observed rate for the direct reduction of FeO.

Jan 1, 1999

By Michel Boisvert

Noranda Metallurgy is presently completing construction of the new Noranda Converter (NCV) at its Home Smelter in Rouyn-Noranda. This capital investment of CDN$56M is the continuation of the Emissions and SO2 Reduction Program that was initiated in the late 1980s with the acid plant for Reactor off-gas treatment. The Patented Noranda Converter was developed and pilot tested at the Home Smelter in the early 1990s. The project will replace the Peirce-Smith Converters and enable sulphur fixation to be 'increased from 70% to over 90% by 2002 with an accompanying reduction of dust emissions to the atmosphere. The construction site is an extension of the present Noranda Reactor area. A number of existing facilities including the acid plant and process air supply were used to minimize the capital cost of the project. This paper provides a brief history of the Noranda converting process, the Home Smelter Emissions and SO2 Reduction Program, ,project implementation and construction, a description of the different facilities, and preparation of human resources for start-up.

Jan 1, 1998

By Anna Wasilkowska

The study concentrates on the effects exerted by microstructure, deformation history and uniaxial stress conditions (temperature, stress state, strain rate) on the mechanical properties offerritic TRIP-aided steels for automotive applications. In low-alloyed TRIP-steels it is quite difficult to separate the effect of the austenite to martensite phase transformation from the influence of the ferritic matrix contributing to the yield stress and uniform elongation. Investigation of transformation kinetics of retained austenite as a function of the deformation temperature show that using the parameter k to characterize the retained austenite stability allows to identify regious of different temperature sensitivity separated by a transition temperature of 10±5°C. The observed low strain-rate sensitivity of the flow stress is an intrinsic property of the ferritix matrix and points to defomtation governed by slip. The ultimate tensile strength is much stronger affected by temperature than the yield stress. The influence of the temperature on the elongation is complex, because of the heating of the specimens by 60-l20°C at moderate and high strain rates. The increase of the total strain can be understood in terms of thermal softening of the ferrite. On the other hand, the steep increase of the stress during dynamic testing is an effect of accommodated elastic and plastic strains in the matrix. The strain- hardening exponent is dependent on the conditions imposed during testing. The martensite transfomtation rate is lower and the critical stress for martensite nucleation is much higher under compression compared to tensile loading. In secondary tensile tests, the yield stress increases steeply, and the ultimate tensile strength and the total elongation depend linearly on the amount of pre-straining. The results confirm that in the range of 8=10-4 s-l the TRIP-effect governs room temperature plasticity. Keywords: TRIP-steels, mechanical properties, strain rate sensitivity, temperature sensitivity, austenite stability

Jan 1, 2003

By David G. Dixon

A mathematical model is derived in dimensionless form which simulates the effluent concentration response of reagents from spent heaps under both fresh and recycled water rinsing. The model is based on dispersion from isochoric pathways distributed in length and cross-section, oriented normal to convection channels in ideal plug flow. The effects of heap height, rinsate flow, and initial reagent concentration are examined. It is shown that the rinsing cycle undergoes a distinct shift between fast and slow rinsing at a certain time depending on the amount of stagnant solution in the heap, and the distribution of dispersion pathways. Results of preliminary column rinsing tests on both agglomerated and unagglomerated ores are presented which partially validate the model.

Jan 1, 1994

By T. H. Jeffers

The U.S. Bureau of Mines' Salt Lake City Research Center. has developed porous polymeric beads containing immobilized non-living biological materials for extracting metal contaminants? from wastewater&. Immobilized biological materials include peat moss, algae, biological polymers, and other materials that demonstrate high .affinities for heavy metals. The beads, designated as BIO-FIX beads, have distinct advantages over traditional methods of utilizing biological materials in that they have excellent handling characteristics . and can be used in conventional processing equipment or low-maintenance systems.. Toxic metals such as copper, cadmium, zinc, lead, and mercury are several of the many heavy metals effectively removed from mine wastewater& using B'IO"FIX beads. Continuous cyclic testing indicated that the beads continued to produce treated effluents which met National Drinking Water Standards (NDIJS) after 175 loading-elution cycles, Adsorbed metals were removed from the beads using dilute ?mineral .acids. In many cases" the extracted metals were further concentrated to enable processors to reclaim the metals, thus minimizing the generation of a hazardous sludge. Tests indicated that use of the beads in a low-maintenance system was particularly effective for treating remote acid mine drainage waters? and small toxic seeps from hardrock mining districts ..

Jan 1, 1991

By Andrzej Warczok

Intensive smelting of copper concentrate in Teniente Converter (CT) leads to the production of high grade matte and highly oxidized slag. Smelting slag is processed in Teniente vascular slag cleaning furnace. The slag composition and forms of copper affect the slag cleaning process and final copper content. Converting of high grade matte in Pierce-Smith converter faces some difficulties in proper slagging of iron oxides. Overblowing in copper making stage allows for slag liquidation but leads to high content of copper oxide in converter slag. Converter slag recycling into CT results in the increase of the participation of oxidic copper. Separate treatment of converter slag and its impact on the forms of copper in CT slag has been analyzed. Thermodynamic properties of a system and kinetic limitations pointed out the negative effect of converter slag recycling on the forms of copper and copper recovery in slag cleaning stage. Experimental results of slag cleaning tests in a crucible scale as well as microscopic examination of laboratory and industrial slag samples supported the above analysis and permitted to formulate recommendations of separate processing of converter slag. Keywords: copper, losses, slag, recycling

Jan 1, 2001

By Jiangtao Li, Zhongwei Zhao, Xingyu Chen, Xuheng Liu

In tungsten ion-exchange process, excessive sodium impurity enters into ammonium tungstate solution. However, the Na content of the final ammonium paratungstate (APT) product must be strictly controlled. Consequently, it is necessary to remove Na from the ammonium tungstate solution during processing in order to obtain the required purity of APT. In this study, porous Na specific absorbent, Na1+xAlxTi2−x(PO4)3, is used to remove Na from the ammonium tungstate solution. Through experiments, the effect of reagent concentration of Na1+xAlxTi2−x(PO4)3, reaction time, reaction temperature and Na concentration on the Na removal were investigated. The results showed that under optimal reaction conditions of reagent amount of NATP 1.0 times of theoretical amount, reaction temperature 25 °C and reaction time 15 min, the Na removal from commercial (NH4)2WO4 solution can reach 98%. Na1+xAlxTi2−x(PO4)3 has a good applicability to different Na+ concentrations. The obtained APT product reaches the national standard purity of zero level.

Jan 1, 2014