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By Peng Lv, Shiqian Liu, Bin Xu, Qian Li, Yongbin Yang, Tao Jiang

The treatment process of a low-grade refractory gold ore containing sulfide minerals and carbonaceous matters was studied in this work. The gold extraction of this ore by all-sliming cyanidation was only 11.75%. Hence, a pretreatment was necessary. In this paper, a flotation-preoxidation-cyanide leaching process was developed. The concentrate from the flotation procedure was processed using different preoxidation methods. A concentrate containing 34.08g/t of gold with the gold recovery ratio of 81.20% was obtained by flotation. After roasting, microwave heating or alkaline pressure oxidation, the gold cyanidation ratio reached 82.37%, 81.26% and 71.09% respectively. Roasting was an effective, reliable and mature technique to oxidize sulfide minerals and carbonaceous matters. Roasting and microwave heating both produced dangerous environmental pollutants while alkaline pressure oxidation was eco-friendly.

Jan 1, 2015

By Mehdi Asadi, Heinz Palkowski

"In recent years, the increased demand for advanced high-strength steels (AHSS) mainly had been driven by the need of the automotive industry to reduce weight and to improve safety. Beside good ductility and high strength, those steels have a high bake hardening (BH) effect, giving additional contribution to the strength of structural parts, subjected to the paint baking process. In this paper we concentrate results gained for hot rolled dual phase (DP) steels.For the simulation of changing process conditions within the final hot rolling the specimens were hot deformed using different schedules of temperatures and reductions, selected according to the non-recrystallization temperature (TnRX). It was possible to refine the DP steel structure by control-ling the deformation temperature and the amount of strain below TnRX during the thermo-mechanical controlled processing (TMCP). This structure refinement resulted in an improvement of the strength and BH behaviour. A wide spectrum of mechanical properties could be obtained depending on the different hot deformation schedules. The best strength and BH levels were recorded for the deformation below TnRX at the highest amount of strain.IntroductionDP steels are characterized by a good formability, high strength and a good compromise between strength and ductility [1]. Moreover, the DP steels exhibit a continuous yielding behaviour, low yield point and a high strain-hardening coefficient [2]. Furthermore, the DP steels often show a large potential for bake hardening (BH). BH refers to the increase in yield strength as a result of the paint baking treatment of the shaped auto-body parts. The primary mechanism that causes the additional strengthening is the immobilization of dislocations by the segregation of interstitial atoms, known as classical static strain aging [3]. The increase of strength thus achieved allows a further reduction of sheet thickness and improves the crash safety and the dent resistance. The BH of special steel qualities is technically used in DP, where e.g. the increase in strength is realized in the final heat treatment [4]. Previous own investigations [5-6] stated that the BH effect of DP is much stronger than that one for conventional BH steels."

Jan 1, 2012

By Tibor Zoltai

Asbestos is a generic term for industrially useful fibers recovered from exploitable deposits of the asbestiform varieties of five silicate minerals: chrysotile, anthophyllite, actinolite-tremolite, cummingtonite-grunerite, and riebeckite. Asbestos and asbestiformm fibers of some other minerals are known to be carcinogenic. Minerals crystallized in the asbestiform habit are characterized by unique properties (morphology, strength and flexibility, physical and chemical durability, and defect-free surface structures). The key to the unusual properties, and health effects, of asbestifarm fibers appears to be in their unusual surface structure. In contrast, non-asbestiform crystals of the same minerals, including the five so-called asbestos minerals do not have these properties and are not carcinogenic (1, 2).

Jan 1, 1989

By Frank A. Stephens

The process of converting iron ore (principally Fe,03 or Fe30,) into iron carbide (Fe,C) to be used as feedstock for steel-making yields complex mixtures of several Fe-containing compounds as a function of processing conditions. In addition to the above compounds (hematite, magnetite and cementite), the mixtures typically contain wustite (FeO) and metallic iron(Fe). Mossbauer spectroscopy has been developed into aquantitative analytical method for monitoring the degree of conversion to carbide from samples periodically extracted from a fluidized bed reactor type of pilot plant. Calibration of absolute quantities of the above five compounds is based on standards prepared from known mixtures of the high purity individual phases. The PC-based spectrometer allows fitting of the well-known spectral components of each of the five phases, the resulting spectral areas then being compared with the calibration curves via PC software to yield the weight fraction of each. Emphasis has been placed on standardizing and simplifying the analysis procedure for routine use in an industrial environment.

Jan 1, 1993

By Ruixuan Zhang, Yan Li, Shusen Cheng

The measurement of raceway temperature in the blast furnace is a critical issue, which is very significant for judgment of, prediction and diagnosis of the racewa yburning state. This paper deals with mathematical models by Monte Carlo method to approximately simulate the radiation heat transfer in the race-way and establish matrix equations using CCD cameras, which are solved to obtain the three-dimensional temperature field. Due to the existence of fluctuation error, CCD camera measurement error and others,this is analyzed and random error is added in the measurement data to demonstrate the effectiveness and stability of the reconstructed temperature field. The results show that the reconstructed three-dimensional temperature field of the raceway is very close to the exact temperature.

Mar 1, 2017

By M. L. Sorokin

The thermodynamic of nickel production from laterite ore and from sulfide concentrate can be analyzed using PO2 - PS2 diagram of the Ni-Fe-S-0-SiO2 system. The procedure of the diagram computation is suggested and the diagrams for various temperature and Fe/Ni ratio are calculated. Three-suffix Margules equations are used for the calculation of the thermodynamic properties of three solutions: liquid matte, liquid slag and solid Fe-Ni alloy. The diagrams are used for the considerations about direct one-stage metallic nickel production.

Jan 1, 1994

By Zhao-feng Xie

A new process of recycling valuable metals containing in the slag of jamesonite smelting in the blast furnace was studied. In this process, the valuable metals such as Pb, Sb, Zn and In etc. were fumed and volatilized and enriched in the dust firstly and then the dust was leached by sulfuric acid. In the leaching procedure, Zn and In in the dust entered into the leaching solution and were separated from Pb and Sb which remained in the residue.The optimal operation conditions of the fuming procedure are as follows: the mass ratio of the blast furnace slag, coal powder and lime are 100:22:10 respectively and the fuming time are 1.5~2.5 h, the fuming temperature is not below 1200C and the volatilization rates of Pb, Sb, Zn and In are 95%, 92%, 86% and 75% respectively. The optimal conditions for the leaching procedure are also presented: the consumption of sulfuric acid is 1.15 times of the theoretical consumption, the ratio of liquid to solid is 4:1 and the leaching temperature, leaching -1time and stirring speed are 90, 1.5h and 300 r?min separately. The leaching rates of Zn and In are 98.5% and 95.2% respectively. The experimental results shows that the valuable metals in the dust can be recovered and separated effectively by this process and the?ir recovery efficiencies are as follows: Pb94%,Sb91%, Zn84% and In69%.

Jan 1, 2009

By Gabriella Tranell

In the manganese ferroalloys industry, there is increasing focus on the performance of different carbonaceous materials within the smelting processes. With a developing scarcity of traditional raw materials, new carbon sources are being identified for potential use in the processes. For this purpose, it is important to be able to predict the suitability of different materials in the process. Hence, the effects of both the physical and chemical properties of the carbon material on the reduction kinetics of manganese and silicon from slag to metal, have been investigated using an advanced sessile drop technique. Using this technique, the reaction patterns of SiO2-MnO containing slag droplets in contact with various solid carbon materials (graphites with different properties as well as cokes and charcoals) at 1400 to 1600\\176;C were studied in-situ. In addition, slag and metal reaction products from kinetic experimental series were analysed. From these results, differences in reactivity between various carbon materials and slags were demonstrated and explained. Mechanisms for both manganese and silicon reduction were proposed.

Jan 1, 2006

By F. Baldini, M. S. Borges

"The proposed method emphasizes the optimization of waste management with regard to the exploitation of raw materials incorporated in the remains of industry, as well as the economics of natural resources as an environmental impact assessment. This system [tool] allows: (a) the conversion of an environmental liability into an asset by finding a line of appropriate research for each type of waste and the development of new materials applicable to other industries, (b) the performance of internal control of the waste generated (production, storage, final destination) as well as legal conformity.Objectives:1.1 General objective:To design a collaborative system for socio-environmental management of industrial waste.1.2 Specific objective:Develop evidence of concepts;Evaluate the deployment of the inventory of waste in an industry;Enable the conversion of an environmental liability into an asset by finding a line of research appropriate to the waste: a case study;Evaluate the environmental legislation in the legal mechanisms that influence company decisions.IntroductionThe global economy is undergoing major changes, among these changes; it should be highlighted those related to technological progress and environmental quality.While the industrialized countries and higher levels of economic growth dominate modem technology, developing countries are identified by a different growth pattern, using the annual growth rate of Gross Domestic Product per capita [3, 18].Growth is when the GDP grows, in percent, over the previous year. Development, on the other hand, is when the countries change their technologies and improve their internal structure. Thus, the growth considers the accumulation of wealth, while the development is concerned with the distribution of wealth, improvement of the quality oflife and environmental quality [3, 18].As the UNESCO report shows (1999), the biggest problem is between consumption and development, what is produced and the end that is given to the product. Therefore, product and by-product have equal importance in the quantity produced [29].On one hand there is a positive relationship between indicators of economic growth and technological progress, however, on the other hand, these transformations are a paradox, confirmed by the dramatic use of environmental resources and the lack of technologies for recycling of industrial scrap."

Jan 1, 2011

By José D. T. Capocchi

Viscosity of liquid lead, tin, and Pb-Sn alloys has been measured by the rotational viscometer method in the temperature range from 50 K above their respective liquidus temperature to 823 K. The results are accurate to within ±1.0 %. The variation of viscosity with temperature followed the Arrhenius-type equation µ = µo.exp(Q/RT). The composition dependence of the isothermal viscosity and the activation energy for viscous flow have not shown anomalous changes at the eutectic composition of the Pb-Sn system.

Jan 1, 2000

By C. Y. Tang, Z. H. Chen, T. C. Lee

"In sheet metal forming process, the forming limit and strain distribution are governed by plastic instability and fracture following strain localization. It has been proved that the temperature gradient caused by plastic deformation as well as friction is one of the crucial factors to induce the strain localization in high-speed metal forming processes. In this paper, a numerical simulation of the sheet metal extrusion process has been conducted by using thermal-mechanical coupling finite element method. An improved mixed finite element method has been used to solve the large deformation elasto-plastic problem. In thermal phase, the transient heat transfer finite element method together with the Crank-Nicholson algorithm has been employed to determine the temperature field. Both the numerical results and the experimental observations reveal that the temperature gradient plays an important role in inducing the strain localization, which eventually leads to fracture failure in the sheet metal extrusion process.IntroductionSheet metal extrusion is such a process where the extrusion punch penetrates into one surface of the sheet metal material to let it extrude and flow towards the outlet of the die. This process can be used to produce protruding parts on a strip material. In engineering applications, the quality of the product is affected by many factors such as stress state, loading speed, material properties and lubrication condition. The research on failure mechanisms and improvement of formability in sheet metal forming processes by exploitation of differential thermal conditions has been of great interest recently [1-3]. It has been proved that the temperature gradient caused by plastic deformation, heat transfer, and friction between sheet and tools is one of crucial factors to affect 'the formability in high speed sheet metal forming processes [4]. In our previous study of sheet metal extrusion, it has been observed that plastic deformation is highly localized and some specimens are subjected to fracture failure in the form of crack propagation [5]. To understand this failure phenomenon, the effects of temperature gradients must not be ignored."

Jan 1, 2001

By Wankun Wang, Fuchun Wang

Based on the study of artificial neural network, the neural model was established for the prediction of germanium extraction from zinc oxide dust by microwave alkaline roasting-water leaching. Alkali-material mass ratio, microwave heating temperature, liquid-solid ratio, aging time, leaching time and leaching temperature were the significant factors for the process. The results indicated that the neural network prediction model was reliable, and the forecast values fitted well with the actual experimental values. The model could be used to predict the regeneration experiments with high credibility and practical significance. The accuracy of convergence of the model reached 10−5.

Mar 1, 2018

By Ming-Feng Ye, Jun Wang, Guang-liang Wu

In order to reduce the Al2O3 inclusions in 50Cr5MoV roller steel produced by EBT-LF-VD-VC process in a steelmaking plant, the LF refining slag was optimized and the influence of optimized slags with different w(CaO)/w(Al2O3) ratios on reducing inclusions were investigated in the laboratory. The results showed that, when w(CaO) = 50–55%, w(Al2O3) = 25–30% and w(CaO)/w(Al2O3) = 1.5–2.0, this optimized slag can not only reduce massive Al2O3 come from aluminium deoxidation, but also change the remain into plastic CaO-MgO-Al2O3 spherical compound inclusions with 1–5 lm diameter, the harm on the performance of the steel was minimized.

Mar 1, 2018

By Arthur E. Morris

Fifty years ago when Professor Yazawa began his career, the field of process simulation and modeling was in its infancy. Since then, tremendous progress has been made in our ability to model metal production flowsheets from mine to refined metal. This progress has come about by parallel developments in basic understanding of process chemistry and in computational techniques. This paper will review the progress made in process understanding and modeling in lead, zinc, and copper metallurgy from its inception to the present, and the role of Professor Yazawa's work in furthering this progress. Specific examples wi1\ be given for the sintering of lead concentrates, slag fuming, zinc concentrate roasting, flash smelting of copper, and pyro-extraction of zinc. Factors limiting further progress will be described.

Jan 1, 2003

By James M. Fragomeni

"The mechanical behavior of an Al-Li alloy was studied and related to the extrusion processing parameters, the plastic metal flow during defonnation, the anisotropy, and the microstructure. The extrusion temperatures, strain rates, extrusion ratios, billet temperatures, and extrusion geometries were varied during processing and correlated with the microstructure and properties. The extrusion processing variables were related to the mechariicar behavior, anisotropy, and microstructure through the ZenerHollomon parameter i.e., the temperature compensated strain rate. Based on optical and electron microscopy studies it was found that regardless of the extrusion conditions, the various microstructures for the most part were unrecrystallized for both the as-extruded and the solution heat-treated conditions. Smaller grain sizes were correlated to larger Zener-Hollomon parameters. The extrusion temperature and ratio did not significantly affect the strength or ductility as did the section geometry, which had a large affect on these mechanical properties. The anisotropy of the properties varied substantially when comparing the extruded longitudinal versus transverse grain orientations.IntroductionThe extrusion process also has a substantial influence on: the microsfructure and mechanical properties of a material that is Athens, Ohio, 45701 fonned The plastic defonnation that occurs during the extrusion process alters the grain size, crystallographic texture, anisotropy, subgrain size, dislocation density and various other microstructural features. Often the material being extruded is not homogeneous, therefore variations in the microstructure and properties occur across the cross-section of the final extruded product. The mechanical properties and microstructure can also vary with length since it is hard to maintain a constant temperature throughout the extrusion process. The extrusion temperature often varies from the heat generated during the extrusion process. The demonstration material that was extruded for this .study was an aluminum alloy containing 2.6wt, % lithium and 0.09wt.% zirconium. This alloy was strengthened by heat treatment causing nucleation, growth, and coarsening of coherent metastable o' (Al3Li) precipitates in the microstructure. The ? precipitates which are a consequence 9f artificially aging the AlLi alloy, are spherical, ordered, and coherent with the aluminum matrix and impede the dislocation glide inotion during plastic defonnation. Theo particles grow homogeneously in the matrix, and have the Cu3Au (L 12)"" superlattice crystal structure. Aluminum-lithium alloys are used primarily for aerospace structural applications since they have attractive properties such as a lower density and higher elastic modulus than conventional 2XXX and 7XXX alloys."

Jan 1, 2000

By R. G. Henley

Mount Isa copper concentrate was combusted in a laminar-flow furnace. The conditions simulated those likely to be encountered in flames in flash smelters of the Outokumpu (air as oxidant) and INCO (oxygen as oxidant) types. The range of conditions studied was as follows: T 400-1400°C, 02 0-100%, SO2 0-95% for residence times up to 0.23 s. The distribution of sulfur, arsenic and lead between the particles and the gas phase was studied. Combustion was very rapid provided the concentrate was adequately dispersed, i.e., no agglomerates. The importance of the latter is discussed. It was possible to oxidize 80% of the sulfur present in the con¬centrate after only 0.1 s reaction time at 1000°C in an atmosphere contain¬ing 8.5% 02 and 12.5% SO2. Best volatilizations (90% of the As, 52% of the Pb) were obtained under localized conditions attained in an air-type flame. Average volatilizations were: air-type flame, As 50%, Pb 32%; oxygen-type flame, As 40%, Pb 30%. The substitution of oxygen for air reduced the arsenic volatilization. The products of combustion were mainly cuprospinel and cuprite; small inclusions of elemental copper were found in some of the particles. At high temperatures, there was a loss of copper due to vaporization of CU( g) CuO kg) (g)

Jan 1, 1983

By P. J. Uggowitzer, H. Kaufmann

"New Rheocasting is a novel route of semi-solid casting, in which the globular semi-solid precursor material is produced by controlled cooling of only slightly superheated melts in conventional steel crucibles. The resulting semi-solid slugs are placed into the sleeve of a vertical Squeeze Casting Machine and then filled into steel dies. Solidification occurs under hydraulic pressures up to 100 MPa Due to the reduced cost of precursor material, reduced investment cost and easier recycling, the New Rheocasting process offers cost reductions of up to 25% over conventional semi-solid casting · routes. The New Rheocast products are pore free, pressure tight, weldable and heat treatable castings.In the present work the New Rheocasting Process is introduced and the influence of heat treatment on mechanical properties of the New Rheocast alloy A356 is discussed.The alloy A356 is cast under ideal New Rheocasting conditions into a step die on an UBE HVSC 350 Squeeze Casting machine. As-east, TS and T6 heat treatment conditions with variations in solutionizing and aging time/temperature parameters are applied and the samples are tested by tensile testing. Alternatively, the same heat treatment conditions are applied to conventional Squeeze Casting parts and compared with New Rheocasting.Questions of potential cost savings due to modified heat treatment conditions are also addressed in this paper."

Jan 1, 2000

By Isrun Bohlinger

Resources recovery of brasses for semifinished products often results in the formation of hard spots impairing the quality of following abrasive and/or surface finishing processes. A short survey is given on the recycling processes, followed by the actual knowlegde of genesis, composition, and possibilities of avoidance of hard spots. Informations on genesis and composition of hard spots are completed by data from recent experiments.

Jan 1, 1998

By Y. Suzuki, J. Nagao, Y. Ueda, K. Shimokawa

"A Ti- Ni intermetallic compound could be formed rapidly from Ti and Ni powder compact with SHS process. Microgravity experiments using a drop shaft are carried out, This report shows the effect of microgravity or high gravity on formability of an intermetallic compound. It is concluded that the specimen forms a porous and nearly amorphous alloy by rapid cooling under microgravity but with rapid cooling under high gravity after microgravity, the specimen forms a uniform and dense structure with better crystallinity.IntroductionTi - Ni inter1etallic co1pounds have been produced and have beco1e si1ilar to the a1orphous and porous structure as a result of the SHS (Self Propagating High-te1perature Synthesis) process under 1icrogravity. SHS process is being applied to the synthesis of cera1ics and inter1etallic co1pounds (1). The technique is characterized by a large a1ount of heat being emitted within a very short ti1e interval as regards the sistering reaction. One SHS process, acco1panying 1elting by a reaction was observed, and that was due to the quick heating of a Ni-Ti co1pact containing 50 ato1ic percent of Ti under a low pressure (2-4). In this report, we have researched the use a drop shaft which is 1ore effective during a short ti1e under 1icrogravity and high-gravity, so as to obtain high dense speci1ens with the exception of porous specimens (5). Mechanical properties of each specimen were esti1ated from these 1icro-structures with a discussion about the effect of changing gravity regarding 1elting and solidification of the Ti-Ni intermetallic comounds."

Jan 1, 1996

By Xie Zhang, Jiang Diao, Xin Qiu, Lu Jiang, Bing Xie, Hong-Yi Li

"Duplex converter process, in which the first converter is used for removing phosphorus from hot metal (De-P), is an important way to produce low P-content and ultra-low P-content steels. In order to improve phosphorization removal and formation of slag with high basicity at relatively low temperature during dephosphorization converter process, effects of temperature, silicon content in hot metal and varied compositions of the De-P converter slag on phosphorus distribution between the slag and hot metal were investigated with thermodynamic calculations and by laboratory scale experiments in present work. Results showed that phosphorus distribution ratio between slag and metal was varied in 10.6~26.6 when basicity of the slag was in the range of 1.5~2.1 at 1370, and the distribution ratio was increased with increasing basicity and Fe10 content in the slag.IntroductionIt is known that phosphorus exists in steel in the form of solid solution, which can significantly improve strength and hardness of steel at room temperature. However, the plasticity and toughness of steel, especially the low temperature plasticity is sharply reduced and leads to high ductile-brittle transition temperature. This phenomenon is commonly known as cold brittleness of steel [1~3]. Hence, phosphorus should be removed as much as possible in the steelmaking process, because it is generally harmful to the iron and steel products."

Jan 1, 2013