Search Documents

By Ann M. Hagni

The mineralogical, chemical, microtextural, and particle size character of electric arc furnace (EAF) dusts are being studied by reflected light microscopy, scanning electron microscope-energy dispersive spectroscopic analysis (SEM-EDS) and electron probe microanalysis (EPMA). The dusts consist predominantly of metallic iron, iron oxide, and calcium-iron-manganese silicate phases, together with smaller amounts of iron-manganese-zinc-calcium, iron-calcium-zinc-manganese, and calcium-iron-manganese silicates. The samples vary in their zinc contents. Chlorine occurs in phases containing iron, lead, zinc, manganese, and calcium. The dust particles range greatly in size from 1 to more than 300 ~m, but most particles are about 1 to 6 ~m. Larger particles. about 20-50 um across. also are present. They are predominantly spherical in shape, but some are cenospheres, and others are more angular particles, some of which are broken spheres and cenospheres. Their internal microtextures exhibit evidence of liquid immiscibility, exsolution, skeletal crystal growth, and oxidation react i on rims. Because EAF dusts have been classified by EPA as hazardous wastes, there is heightened interest in the treatment of these dusts to render them non-hazardous. The mineralogy of products of pyrometallurgical treatment of EAF dusts by flash furnace and pyrohydrolysis are currently under study.

Jan 1, 1991

By Xuerong Wen

The oxidation behavior of TiAl3 intermetallics was investigated as a hnction of time at 1273K in pure dry oxygen. The oxidation experiments were carried out using TGA method. The oxidation scales were analyzed using SEM, EDS and X-ray diffraction methods. The structures of oxides formed at the different oxidation times were analyzed. The mechanism of oxidation of TiAl3 intermetallics was discussed.

Jan 1, 1998

By Jorge Alberto Soares Tenório, Romano Espinosa, Felipe Fardin Grillo, José Roberto de Oliveira, Denise Crocce

"The aim of this work was evaluation of the recovery of Zn and Fe of the EAFD added to the hot metal in the form of briquette at temperature of 1500°C. The EAFD was agglomerated by cold briquetting and introduced in the hot metal. This study utilized a bench-scale equipment to melt, during this process to kept a flow rate of inert gas above the bath. Were collected periodically metal samples and the samples were analyzed for determination of the content of total silicon and carbon by chemical analysis. Zinc oxide, zinc ferrite and other oxides were reduced and were volatized and collected by a cleaning system of dust (baghouse) located on top of the oven. More than 98% of iron were recovered from EAFD during the test. It was possible to produce a dust containing about 68% zinc by means of adding of EAFD.IntroductionIn the first semester of 2010, steel production was about 706 million tons, 27.9 % more than in the first half of 2009. Not a significantly increase if 2010 data is compared with the first semester of 2007 (only 7.2 % higher), before the world’s economic crises. Steel production is divided into two main routes. The first one, and most used, is the Basic Oxygen Furnace Process (BOF process), which in 2008 accounted for approximately 67.1 % of steel production. The second route is carried out in the Electric Arc Furnace (EAF) that in 2008 represented 30.6 % [1 ].Electric arc furnace dust (EAFD) is a solid waste generated during the steel making process. It is classi?ed according to NBR 10004 as dangerous solid waste-class I, because the elements Pb e Cd leach in water exceeding the maximum limits permitted by the NBR 10004 [2 ]."

Jan 1, 2012

By R. Angulo

Carbon nanotubes (CNTs) have recently emerged as materials with outstanding properties. This has promoted their consideration as reinforcements for other material systems, such as ceramics. However, one of the fundamental problems with producing CNT-reinforced ceramics is the effective dispersion of CNTs during processing. This has been successfully carried out recently using organic solvents. This paper is a preliminery investigation into the rheological behavior of aqueous CNT-alumina slips, with the objective of moving towards a more environmentally friendly aqueous tape casting process for the production of CNT-ceramic composites.

Jan 1, 2008

By Jiayan Li, Yi Tan, Yao Liu, Yaqiong Li, Shenrui Wu

"A metallurgical grade silicon (MG-Si) refining concept process was presented. Under vacuum conditions, silicon was selectively oxidized by high purity silicon dioxide to form gaseous silicon monoxide while impurities with low vapor pressure in MG-Si were rejected in residue; Then high purity silicon was obtained from the disproportionation of condensed silicon monoxide; and by-produced silicon dioxide was recycled for the oxidation step. Thermodynamics on boron rejection during the oxidation were studied in this work. In the temperature range of 1200-1800K, the saturated vapor pressure of boron, and the Gibbs free energy changes, the equilibrium partial pressures of silicon monoxide and boron oxides of potential reactions were calculated. And the effect of boron activity in MG-Si was also discussed. The results indicated that boron in MG-Si can be rejected during the oxidation and it showed the potential for the further development of the new refining process.IntroductionAs global energy consumption growing dramatically, higher prices of energy and global warming problem have attracted more and more attention [1]. As a clean and renewable energy industry, the photovoltaic (PV) industry converts solar energy to electricity using solar cell device and has a growth rate of about 30% in recent years. It has caused a shortage of silicon feedstock due to that about 90% of solar cells are made of crystalline silicon. And high energy consumption during the production of silicon material, i.e. solar grade silicon (SoG-Si), is main obstacle for its mass production."

Jan 1, 2012

By Patricio Ruz, Gabriel Riveros, Carolina Ramirez, Andrzej Warczok, Rober Treimer

"Continuous converting of copper matte produces slag with high cuprous oxide content. The corrosion of chrome-magnesite refractories with slag of high cuprous oxide content is a major problem. Properties of olivine type of slag make the slag very attractive for matte smelting and converting.Analysis of phenomena determining the slag infiltration into the porosity of a refractory and dissolution of refractory components in the slag allowed for better understanding of the mechanisms of refractory destruction.The results of laboratory scale tests of the olivine slag infiltration into open porosity and corrosion showed dominating effects of slag temperature and cuprous oxide content. The optical and X-ray examination of slag samples permitted the definition of the mechanism of formation of new phases and refractory deterioration. 71"

Jan 1, 2009

By Xiang Zhu

Xidagou is the largest waste water discharge channel of the Anshan Iron and Steel Complex (AISC) with average flow rate of 8000 cubic meters per hour, which is about 75% of the total effluent of the AISC. The waste water from Xidagou seriously polluted the Taizi River Basin. In order to meet the Chinese Class V Standard for Surface Water Discharge and the Standard for Recycled Industrial Water Reuse, with the aid of the World Bank, the AISC began the treatability studies in 1991. Based on the bench-scale test, the AISC carried out pilot-scale treatability studies on three different treatment processes and five different chemical coagulants for more than half a year in 1992. The study results show that the processes of primary sedimentation- chemical mixing and flocculation-secondary sedimentation-filtration can meet the requirement and that PFS and PAM are effective and economic chemical coagulants.

Jan 1, 1994

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 Eren Hüseyin Obuz

In this study, the leaching kinetics of rare-earth elements were investigated using HCl and HNO3 solutions. A standard crushed complex ore was utilized as raw material. The complex ore (particle size of under 54 μm) contains REE (Ce, La, Nd, Pr, etc.). Different leaching durations were selected for the kinetic studies. The highest leaching efficiency was obtained in HCl solution, and the leaching mechanism was identified to diffusion through a product layer. The rate constants of Ce, La, Nd, and Pr were calculated as 1.08 × 10−2, 0.86 × 10−2, 1.87 × 10−2, and 1.34 × 10−2 h−1, respectively.

By Esperidiana A. B. Moura, Célio H. Wataya, Roberta A. Lima, Rene R. Oliveira

The purpose of this study was to investigate the mechanical, morphological and thermal properties of biodegradable composites based on aliphatic-aromatic copolyester/polylatic acid blends (PBAT/PLA blends) reinforced by açaí seed fibers, an abundant byproduct of the açaí fruit agro industry. The biodegradable polymeric composites were prepared by melting extrusion process using a twin-screw extruder machine. The fibers removed from the açaí seed were used as the reinforcement and PBAT/PLA blends as the matrix. The influence of the açaí seed fibers addition on properties of composites was investigated by tensile and impact tests, SEM, DSC, and XRD analysis. Correlation between properties was discussed. In addition, açaí seed fibers characterization by SEM, XRD and WDXRF have also been carried out. The addition of açaí seed fibers on biodegradable PBAT/PLA blends showed that it is possible to get interesting property gains in biodegradable polymer by using waste from renewable sources.

Jan 1, 2015

By Ting Liu, Qian Li, Peng Deng

The wastewater containing Hg2+ and Pb2+ does great harm to the environment and human bodies. Traditional wastewater treatment cannot fundamentally put a stop to heavy metals pollution for producing secondary pollution. In this paper, Hg2+ and Pb2+ in wastewater were removed and recovered by sulfide precipitation- flotation. Sodium sulfide was used as precipitant and butyl ammonium aerofloat was used as collector. Results indicated that Hg2+ and Pb2+ could be reduce to less than 0.03mg/L and 0.16mg/L respectively by both coprecipitation- floatation and fractional precipitation- floatation. In these two methods, fractional precipitation flotation could not only remove Hg2+ and Pb2+ from wastewater, but also could recover mercury and lead effectively. The infrared spectrograms showed that the adsorption between butyl ammonium aerofloat and mercury precipitate or lead precipitate is chemisorption.

Jan 1, 2015

By Chuanfu Zhang

Based on Thermogravimetric and Differential thermal analysis (TGA-DTA), porous copper powder is prepared by thermal decomposition of complicated copper oxalate. The effects of various conditions on the morphology, crystalline grain size and specific surface area of copper powder were investigated, including temperature, duration, mixing ratio of nitrogen and hydrogen. Furthermore, composition and morphologies of the products were characterized by X-ray diffraction (XRD), Scanning electron microscope (SEM) and BET adsorption isotherm. It is found that porous copper powder was produced under optimum conditions. The specific surface area is over 6.74 m2?g-1, and average pore size in particles is about 30.3 nm. After comparison of SEM images, the final product Cu well inherits the morphology of the precursor, thus a mechanism of in-situ decomposition is proposed.

Jan 1, 2009

By Chonghe Li, Xionggang Lu, Wei Xiao, Xingli Zou, Weizhong Ding

The reduction degree and rate of the initial ilmenite concentrate and pre-oxidation samples by hydrogen were investigated by using thermogravimetric analysis system. H2-TPR was used to detected reduction properties of the pre-oxidation products which were oxidized at different temperatures. The phase transformations and micromorphology changes during pre-oxidation and hydrogen reduction were identified by XRD and SEM. The FeTiO3 was decomposed into TiO2 and Fe2O3 at the temperature below 900 oC. With the temperature rising, Fe2TiO5 was the only stable phase in high temperatures. The reduction of pre-oxidation ilmenite concentrate was faster than the natural sample, which was attributed to the micropores generated on the surface of ilmenite concentrate during oxidation. The main phases of the reduction product were metallic iron, ferrous pseuodbrookite.

Jan 1, 2014

By Tobias Dubberstein, Hans-Peter Heller

The viscosity of Fe-Cr-Mn-Ni TRIP/TWIP (Transformation Induced Plasticity, Twinning Induced Plasticity) steel with varied nickel content is investigated using a vibrating finger viscometer. The viscosity of the melt is calculated from the change in power input in the field coil by an immersed finger into the liquid steel to maintain a constant peak-to-peak amplitude of the sine wave of oscillator compared to the idle state. Nickel content in steel is varied from 3 wt% to 9 wt%. The dynamic viscosity (η) at 1600 °C for 3 wt% Ni is 3.73±0.14 mPas, for 6 wt% Ni 3.50±0.03 mPas, and for 9 wt% Ni 3.93±0.09 mPas. There is a kink from low to high nickel content in viscosity values of Fe-Cr-Mn-Ni alloys. This phenomenon can be explained by a change in coordination number in the melt, as reported for Fe-Ni binary system in literature. The availability of viscosity data delivers relevant input to model free fall atomization processes of FeCrMnNi alloys.

Jan 1, 2015

By Jianjun Wang, Jiaqing Peng, Lingen Luo, Zhenbang li, Yinghe Lin

Copper removal from ferronickel by FeS has been exploring studied. It is found that the decopperizing agent FeS makes the copper removal in ferronickel effectively. The effects of FeS addition amount, carbon content in ferronickel and experimental temperature were investigated. The results showed that the removal rate of copper in ferronickel increased with the amount of FeS increasing. When the dosage of FeS is 20% (mass percentage)，the removal rate of copper can reach higher than 11%. The rate of copper removal rises with the amount of carbon content increasing in ferronickel. When the amount of carbon content is 1.86%, the removal ratio of copper is 41.3%. Higher experimental temperature promotes the copper removal reaction in certain extent. The flux is acidity and weak oxidative can also promote the reaction of copper removal.

Jan 1, 2015

By Paul S. Korinko, Simona E. Hunyadi Murph

To address a radiological contamination event, a materials and process project was initiated. During the course of this project, processes and materials were developed that successfully captured zinc vapors physically and chemically, respectively. However, the physical traps were placed in an undesirable area and it was determined that the chemically captured zinc reactions was reversible. Consequently, advanced nanomaterials are being developed to capture zinc vapors. The current state of the art of the science and engineering of these materials and their efficacy for zinc capture and retention is discussed in this paper.

Jan 1, 2015

By XING Xiangdong, Zhang Jianliang, MA Jinfang, WANG Zhenyang

The non-equilibrium reflux reaction behavior of phosphorus was studied with synthetic slags formed by using the AR chemical reagents and changing the initial condition of basicity, FeO, MgO and Al2O3. Due to increase of viscosity, the dephosphorization slag with high basicity inhibits the full contact of slag with iron, which leads to the low reaction rate in the early stage. However, since the high basicity improves the activity coefficient of CaO, the dephosphorization rate and phosphorus capacity goes up in late reaction stage. FeO promotes the increase of reaction rate in early dephosphorization stage. But the polarization force of Fe2+ is stronger than Ca2+, which hinders the reaction between phosphate ion and CaO and reduces the stability of PO4 3-. Thus, high content of FeO will adversely impact on dephosphorization reaction. In addition, MgO has a promoting effect to the dephosphorization, whereas Al2O3 has a negative influence.

Jan 1, 2016

By Jianguo Yin, Wenqiang Yang, Xiaoli Yuan, Juan An, Wentang Xia

Low grade iron ore with phosphorus (LGIOWP), a raw and wasted industrial solid material was used as an adsorbent to remove Pb(II) from wastewater. The effects of initial pH value, adsorptive time, initial Pb(II) concentration, adsorptive temperature and LGIOWP dosage on the Pb(II) removal efficiency were studied. The results show that the Pb(II) removal efficiencies exceed 99.4% and Pb(II) concentrations are less than 0.30 mg/L under the conditions of pH value 7.0, adsorptive temperature 50 oC, adsorptive time 30 min, initial Pb(II) concentration 100 mg/L, particle size <0.25 mm, adsorbent dosage 5 g/L and stirring speed 260 r/min. After Pb(II) removal reaction, the Pb(II) concentrations of wastewater completely accord with the requirement of national discharge standards of pollutants from lead and zinc industries (GB 25466-2010) (TPb= 0.5 mg/L) in China. Therefore, it can be concluded that LGIOWP is a new low-cost adsorbent which is suitable for the adsorption of Pb(II) from wastewater.

Jan 1, 2015

By Maria K. Kojo

The interaction between various slags and a nickel concentrate containing pyrite, pentlandite, and violarite were investigated by submerging concentrate pellets in molten slags. The slags were contained in MgO-A12O3 spinel crucibles. The slag oxidizes the iron sulfides in the concentrate, resulting in a nickel matte. The amount of S02 gas formed during reaction was measured to determine the oxidation reactivity of the slags. The experimental variables included temperature, the ferric/ferrous ratio of slag, and other slag properties such as the FeO/SiO2 ratio and the MgO and NiO contents. The reactivity of the slag depended in a complex manner on its oxidizing power, viscosity, and interfacial tension. The slag composition for the greatest reactivity was determined to be Fe3+/Fe2+ = 0.3, Fe/SiO2 = 1.3, and % MgO = 2. This slag, however, caused substantial foaming. Increasing the MgO content to 10% or replacing it by 5% MgO + 8% NiO eliminated at a slight decrease in reactivity. The implications of the findings from this work in the bath smelting of nickel sulfide concentrates are discussed.

Jan 1, 1995

By Michael Altepeter

Big River Zinc Corporation, located in Sauget, Illinois, operates a neutral leach residue circuit. The residue produced in the circuit is sold to lead smelters for subsequent recovery of valuable metals. A research program was initiated several years ago to find a means of treating the residue at Big River Zinc to recover the valuable metals. The Ausmelt submerged lance reactor was selected as the best alternative for the first step of the process. Pilot scale tests were conducted at Ausmelt&apos;s facilities in Melbourne, Australia. Separations were excellent. 99%+ of the Zn, Pb, Cd, and Ag contained in the residue reported to the oxide fume. 99%+ of the SiO2,, Fe, Mg, and Ca in the residue reported to the slag which passed the EPA TCLP test. Subsequent leaching of the oxide fumes and purification of the leach solutions using conventional procedures produced solUtions suitable for zinc electrowinning and an upgraded lead sulfate cake for sale.

Jan 1, 1992