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By Wing Ka Ng

Substitution of pulverized coal injection by solid biocarbon fuel has the potential to achieve substantial reduction in GHG emissions associated with blast furnace ironmaking. A systematic evaluation was conducted on the performance of solid bio-carbons produced from a single raw biomass source using different pyrolysis technologies. The potential of solid biocarbon in reducing GHG emission of the blast furnace ironmaking process is strongly influenced by its O/C mass ratio. In order to achieve substantial GHG reduction, it is necessary to replace coal injection by solid biocarbon having a low O/C mass ratio. The pyrolysis technology and conditions employed are key parameters influencing O/C mass ratio of the resultant solid biocarbon. Close collaboration between steelmakers and solid biocarbon producers is critical for producing suitable solid biocarbon fuel to replace pulverized coal injection. A successful partnership should pave the way in achieving substantial reduction in GHG emissions of the blast furnace ironmaking process.

By Vitalij K. Pecharsky

Recent interest in complex aluminohydrides as potential near ambient, ultra-high capacity, solid-state sources of hydrogen (e.g., for fuel cells) calls for an improved understanding of the processes occumng in these hydrogen-containing materials during both the release and the uptake of hydrogen. Lithium aluminohydride (LiAlH4) rapidly releases 5.2 wt. % of hydrogen (i.e., nearly four times more than LaNis-based alloys) during mechanochemical processing at ambient conditions in the presence of transition metal catalysts. Using a variety of solid-state characterization techniques, the mechanochemical transformations in a series of LiAlH4 - metal catalyst systems have been examined and preliminary insights on the mechanism have been obtained. Surprisingly, the well-known hydrogenating-dehydrogenating catalysts, such as Ni and Pt, are practically inactive in the mechanochemical dehydrogenation of LiAlH4.

Jan 1, 2002

By Shadia J. Ikhmayies

CdSxTe1-x and CdS1-yTey solid solutions are usually formed in the interfacial region in the CdS/CdT thin film solar cells during the deposition of the CdTe layer and/or the processing steps of the device. It is well known that CdCl2 heat treatment encourages the formation of the CdSxTe1-x alloy which improves the solar cell performance. In this work, indium doped CdS1- yTey thin films are produced by first producing CdS:In thin films by the spray pyrolysis (SP) technique on glass substrates, then annealing the films in nitrogen atmosphere in the presence of elemental tellurium. The films are characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and transmittance measurements. The transmittance is used to deduce the optical parameters such as; the extinction coefficient, refractive index, besides to the real and imaginary parts of the dielectric constant. The dispersion parameters such as Eo (single-oscillator energy) and Ed (dispersive energy) of the deposited films are also estimated and discussed.

Jan 1, 2015

By Daniel Bennett

There are few methods currently applied towards on-line bulk mineralogical analysis. Yet on-line knowledge of process mineralogy could potentially provide large benefits, such as increased extraction efficiency or resource optimization. The work described in this paper involves the development of radio frequency methods for bulk mineralogical analysis. Some resonances that occur in the radio frequency spectrum are mineral specific, and potentially allow quantitative estimation of mineralogy in an ore stream. Results will be presented on the specific detection of chalcopyrite. Initial quantitative measurements investigating matrix effects have indicated the feasibility of on-line mineralogical estimation using radio frequency techniques.

Jan 1, 2006

By P. N. Anyalebechi

The effects of application of steady and pulsed electric current on the cast microstructures of ingots of a 7050 type aluminum alloy have been experimentally investigated over a solidification rate range of 0.1-10 K/s. This involved the application of an electric current of 465-930 mA/cm2 of melt surface area to laboratory-size ingots solidified in a unidirectional manner. Within the ranges of electric current density and solidification rate investigated, the applied electric current reduced the average dendrite, grain, and second-phase particle size. It also made the size distribution of the second-phase particles more uniform. The mechanism for the observed refinement of the cast microstructure by the applied electric current is not well understood. The potential effects of heat-induced local convections, shear stress-induced fragmentation of dendrites, increased temperature gradient due to Joule heating and the thermal and constitutional supercooling engendered by Peltier, Thompson, and Joule heating are discussed.

Jan 1, 2009

By Zan Yao, Sha Lv, Geoff Wang, Baojun Zhao, Zongze Huang, Jin Zou, Xiaodong Ma, Zhouhua Jiang

55SiCr steel is one of the important spring steels widely used in automobile manufacturing. The presence of micro inclusions in the steel can significantly influence a number of spring properties such as fatigue strength. It is important to understand the mechanism of the inclusion formation so that size and proportion of the inclusions can be controlled. Inclusions in Si-killed 55SiCr spring steel have been analysed by scanning electronic microscopy and electron probe X-ray microanalysis. The chemistry of the inclusions observed in 55SiCr steels can be represented by the SiO2–Al2O3–CaO–MgO system. It was found that the compositions of the inclusions cover a wide composition range, which indicates that these inclusions were formed from different reactions. The possible mechanisms of the inclusion formation are discussed. It would be possible to characterize and manage the inclusions in the spring steels deoxidized by Si.

Mar 1, 2017

By Gökhan Hardal, Berat Yüksel Price

Nickel manganite based negative temperature coefficient (NTC) thermistors have good temperature sensor characteristics and electrical stability for temperature measurement applications. In this study, the electrical and microstructural properties of Ni0.5Co0.5Cu0.3Zn0.3Mn1.4O4 NTC thermistor were investigated. The samples were fabricated by the conventional solid-state reaction method. The powders were calcinated at 900 °C for 2 h and the samples were sintered at 1200 and 1300 °C for 5 h in air. The bulk density of samples was 5.07 and 4.96 g/cm3, respectively. The microstructure of samples was observed using a scanning electron microscope. The electrical resistance was measured in a temperature programmable furnace between 25 and 85 °C. The electrical resistivity of the Ni0.5Co0.5Cu0.3Zn0.3Mn1.4O4 sample increased from 52 Ω cm to 95 Ω cm when the sintering temperature increased from 1200 to 1300 °C. The material constant “B”, sensitivity coefficient “α” and activation energy “Ea” values were also calculated for the NTC thermistors.

Mar 1, 2017

By Sergio N. Monteiro, Artur C. Pereira, Foluke S. Assis, Henry A. Colorado

The fique fiber is an important natural fiber, originally from Colombia where it is used for sacks and crafts while its plant is used to contain slopes. However, few studies were realized with the fiber obtained from the fique plant leaf, its mechanical properties are superior in many aspects in comparison to some other lignocellulosic fibers. This work investigated the toughness behavior of polyester matrix composites reinforced with up to 30% in volume of a fabric made of fique fiber by means of Charpy impact tests. It was found that the addition of fique fabric results in a marked increase in the absorbed energy by the composites. Macroscopic observation of the post-impact specimens and SEM fracture analysis showed that transversal rupture through the fique fabric interface with the polyester matrix is the main mechanism for the remarkable toughness of these composites.

Mar 1, 2017

By C. W. Whitten

Solis from an abandoned Pb battery processing facility were characterized prior to the selection of the extraction technique. Reflected light microscopy and electron beam methods were used to locate Pb-bearing phases and to quantify the compositions of the phases. It was found that the soils are composed primarily of quartz and feldspars with minor amounts of iron and titanium oxides. Lead is primarily present as an oxide or sulfate that is associated with the silicate minerals. Specific phases identified were PbO; Pb02; cerrusite, PbCO3; angleslte, PbSO4; galena, PbS; and magnetoplumbite, 2PbO3Fe2O3; or plumboferrite PbO2Fe2O3?

Jan 1, 1989

By Tsutomu Yamamura

The electrolytic reduction mechanism of rare-earth chlorides such as LaCl3, CeCl3, NdCl3, ` SmCl3 and DyCl3 in alkali chloride baths has been investigated in NaCl, KCI and eutectic LiCI- KCI by means of electrochemical transient methods. The thermodynamic behaviors of rare-earth containing species have been discussed in the frame of Electrode potential - P02- diagram. Low current efficiency found in the case of Nd electro-winning has been attributed to the dissolution of Nd into the bath. The analyses of electrochemical measurement required the elucidation of the effects of the factors such as under-potential deposition, metal dissolution, moisture and oxygen partial pressure.

Jan 1, 2003

By Yuanbo Zhang, Zijian Su, Bingbing Liu, Guanghui Li, Tao Jiang

With the depletion of rich manganese ores, high-Fe content manganese ores are becoming the mainstream resources for manganese extraction. Reduction roasting-magnetic separation process is reported as a relatively effective route to realize the separation of manganese and iron. This study investigated the phase transformation of MnO2 and Fe2O3 briquettes (molar ratio 1:1) roasted under various temperatures and CO–CO2 atmospheres. Results showed that when the CO content was in the range of 0–10 vol%, MnxFe3−xO4 (x = 0−1) phase was formed and its content increased with the rising of temperature. The formation of ferromagnetic MnxFe3−xO4 with strong magnetism resulted in an inferior separation of manganese and iron by magnetization roasting-magnetic separation process. With the increase of CO content to over 25 vol%, the MnxFe3−xO4 content decreased while the content of feebly magnetic substance (MnO)y(FeO)1−y(y = 0−1) increased. Further increasing the CO content to over 80 vol%, (MnO)y(FeO)1−y was reduced to MnO and metallic iron.

Mar 1, 2017

By R. David Prenganan

RSR has developed a new environmentally superior process to recover lead as high purity electn:1o'i0!1 cathode from battery scrap. The process involves crushing the batteries, separating the lead bearing material from the plastic, ebonite and separators, and separating the active material (paste) from the metallic lead fraction. The paste is desulfurized using Na2C03 to convert the PbS04 to PbC03 and produce a sodium sulfate solution. The paste is further treated to decompose the PbO2 and PbC03 to Pbo. The PbO from the treated paste is easily leached, using H2SiF6 and electrown from solution using Pbo2?coated graphite anodes. The electrown lead has a purity exceeding 99.99%. RSR is in the final design stages of a plant to produce 36,000 tons per year of electrcwon cathode from battery paste in a new plant adjacent to the present Indianapolis refinery. This paper describes the work of a pilot facility operated in the early 1980's. The paper describes the patented process in detail and compares the newly designed environmentally clean electrolytic plant to present recycling plants.

Jan 1, 1990

"EAF dust is categorized as a hazardous solid waste. EPA approves only two treatment methods: either sending the dust to zinc recycling facility, or stabilizing it first and then disposing it to a specially-lined landfill. Both treatment methods are costly to EAF steelmakers. In order to reduce the cost and even better to make profit from the dust, EAF steelmakers need to find a costeffective technology to separate zinc from EAF dust. This paper is dedicated to discussion of a novel recycling strategy: in-process separation of zinc from EAF dust. The concept of in-process separation of zinc from EAF dust is first defined, and then a simple Zn concentration model is developed. From this model, two approaches of in-process separation of zinc from EAF dust are derived: (1) prematurely capturing dust at very high temperature when zinc is still in vapor status, (2) prematurely collecting dust immediately after quickly cooling EAF off-gas from high temperature to low temperature. Next, thermodynamic analysis is conducted to understand zinc behavior in EAF off-gas. It is demonstrated in theory that zinc is in vapor status while it exits from electric arc furnaces. At last, recycling routes and economics of in-process separation of zinc from EAF dust are discussed.IntroductionElectric arc furnace (EAF) plays an increasingly important role in steel production. According to USGS, steel production from electric arc furnaces has long exceeded that from basic oxygen furnaces [JJ. In 2009, electric arc furnaces produced 64% of total steel in the United States.Along with the fast growth of EAF steel production, generation of EAF dust is also rapidly increasing. A survey by AIM Market Research showed that 10 - 20 kg EAF dust was generated for every ton of EAF steel produced [2] In 1999, the United States alone produced 770,000 metric tons of EAF dust [3] In Europe, annual generation rate of EAF dust is more than one million tons [4-5]. In Japan, about 450,000 tons of EAF dust is produced each year [6] Globally, total generation of EAF dust was estimated to be more than 5 million tons per year [5] EAF dust is categorized as a hazardous solid waste since it often contains heavy metals, such as lead, chromium and cadmium. US Environmental Protection Agency (EPA) approves only two methods for treating EAF dust: (1) recycling the dust by EAF-dust recyclers, and (2) specially landfilling the dust for disposal after it is chemically stabilized. These two methods of treating EAF dust are both very costly to EAF steelmakers. It was estimated that a fee of $150 to $200 per ton of EAF dust was paid for various treatment options, which added approximately $2 - 3 cost for every ton of liquid steel produced by electric arc furnaces [?J."

Jan 1, 2011

By Vijaya Thangavelu

Biological leaching of low-grade nickel laterite is based on a non-traditional leaching of oxide minerals using heterotrophic micro-organisms. The organisms solubilise metals by excreting organic acids; these acids then form complexes with heavy metals. High salinity of water supplies and soils in the vicinity of nickel laterite ore bodies is a major abiotic stress to fungi and represents a major challenge in the application of bioleaching process in-situ. Salinity exposes fungi cells to Na+ toxicity and osmotic stress. This study examined the salt tolerance development of Aspergillus foetidus based on gradual acclimatization of organism, its salt threshold and the salinity effect on its metabolism. The biological leaching of weathered saprolite ore with the resulting halotolerant organism under saline conditions was assessed. It was observed that salinity stress affected the organism?s growth and energy utilization

Jan 1, 2006

By D. R. Spink

A partial desulfurization roasting (PDR) technique has been developed for use on zinc concentrates whereby the sulfide sulfur associated with the iron content is selectively removed over a very short residence ?time in the roaster. The resulting PDR product is then leached for the selective removal of the iron. The resulting leach restdite is an upgraded zinc sulfide concentrate which has a very low iron content. The up-graded zinc concentrate can be subjected to a conventional dead roast without formation of deleterious zinc ferrite so that hot acid leaching and jarosite (or other) iron precipitation steps are obviated. Examples are presented for the treatment of three very different types of zinc concentrates.

Jan 1, 1990

By Maria D. Salazar-Villalpando, Anthony Cugini, Bryan Reyes

"The electrochemical reduction of CO2 was performed in a laboratory-made, divided Htype cell. A copper electrode was used as the cathode. An Aldrich Nafion 117-type ion exchange membrane (0.18mm thickness) was used as the diaphragm. NaHCO3 and KHCO3 were studied as the catholytes. Hydrogen evolution from water reduction and products from CO2 electrochemical conversion were recorded. Higher CO2 reduction enhancement was observed by KHCO3 as compared to NaHCO3. The main conclusion of this work is that in fact CO2 can be electrochemically reduced with copper electrodes.1.-INTRODUCTIONThe direct electrochemical reduction of CO2 may allow for a simple process and, by avoiding high temperature reactors, would enable the process production rate to be quickly varied to follow the time of day availability of surplus electricity [1]. Temperature has a major effect on the electrochemical conversion of CO2 since its solubility increases when temperature decreases [2]. The electrical potential applied to the electrochemical reacting system will have an influence on the product distribution, as well. For example, a narrow potential range during cyclo-voltagraphic studies will determine the detection of a lower number of products. A recommended potential range to study the electrochemical reduction of CO2 is -2V to 2V. Moreover, the reaction rate on the electrode is governed by various processes, such as the kinetics of electron transfer, adsorption/desorption at the electrode surface, and diffusion of CO2 to the Cu electrode. The availability of active species, CO2 for electro-reduction, is extremely low at the vicinity of the electrode surface and it seriously interferes with the rate of mass transfer. In batch type electrolytic reactors, depletion of CO2 at the surface takes place first. CO2 from the bulk then has to diffuse to the electrode surface, resulting in mass transfer controlled kinetic phenomena. During the above process, several other competitive side reactions could suppress the primary reaction even though the cathode has good electro catalytic properties for reduction of carbon dioxide. When the dynamic supply of specific active species is ensured to electrode surface, the mass transfer effects are minimized to certain extent. Hence it is envisaged that a continuous flow reactor is more efficient for the electro-reduction of CO2 in CO2 saturated aqueous electrolytes. The primary reactions that occur at the copper electrode during the reduction of CO2 are listed below (with the standard potentials calculated using formation energies [1] :"

Jan 1, 2010

By Ramana G. Reddy

In the past, many lead-containing slags and wastes were stored in piles or landfills. However, shortages of landfill space as well as increased public, concern about the toxic nature of disposing lead containing industrial wastes in landfills have led to review of disposal methods. Several lead wastes are processed to provide commercial products. They are used on-site in land reclamation projects. or are processed and sold as a by-product. These by-products contain nutrient elements needed for plants or animals and also may contain heavy? metal contaminants such as As, Cr. Cu, Zn and Ph. Use of such by-products containing unacceptable levels of these contaminants could cause plant and animal toxicity. In this paper. role of viscosity in conversion of lead slag wastes into commercial products containing ,low content of lead and other, heavy metals is presented. Effects of slag viscosity on the velocity of movement of metal' and matte prills through themolten slag layer in the melting furnace is discussed. Current and emerging slag cleaning technology, foamed, granulated and pelletized slag technologies are reviewed.

Jan 1, 1995

By Kwong. Kyei-Sing

Gasification is a process that converts a carbon feedstock into synthesis gas (CO+H2). Slagging gasifiers operate at high temperature and pressure and in a corrosive-wear environment from the slag. Cr2O3-based refractory linings are used to protect the steel vessel that comprises the gasifier from the aggressive gasification environment. Increasing service life of the gasifier is one of the keys for wide spread development of this technology. In support of the goals, research on the gasifier atmosphere, the slag chemistry, the interaction of Cr2O3 refractory with different feedstock mixtures (e.g., coal and petcoke) were characterized by post mortem analysis of bricks from service in gasifiers and thermodynamics simulation of the environment. Examples demonstrating how thermodynamic calculations can explain the post mortem results and make predictions of material interactions will be given. Attention is placed on the possibility of Cr+6 in different feedstock mixtures and operating conditions.

Jan 1, 2010

By Shengli Wu, Yuandong Pei, Shaoguo Chen, Zhixing Zhao, Haijun Kang, Jiangshan Shi, Wen Pan, Zhengming Cheng, Yaosheng Luo

Grate bar is the key component of the sinter machine used for loading sinter and raw materials. Bar channels are sometimes bonded into blocks, which affects the service life of bar, and more importantly reduces the effective ventilation area of the sintering, affecting the normal production of sintering, resulting in unstable negative pressure, higher electricity consumption, and lower production and quality of sinter. In order to solve this problem, the systematic study was done on bonding materials of bars, based on which bonding mechanism of sinter grate bars was obtained. The KCl is an important characterization of bonding. Control standard of blending ore that prevents bonding is K2O content below 0.06% and Cl content below 0.05%.

Mar 1, 2018

By Shi Yuan

Molten copper was deoxidized using a one-end-closed yttria-stabilized zirconia (YSZ) tube. A thin layer of porous Ni-Zr02 cermet electrode was deposited on the inner wall of the YSZ tube. The outer surface of the tube was in contact with the melt and the inner surface with a flowing reducing gas. Without applying external EMF, the melt was deoxidized by short-circuiting the melt with the cermet electrode. The deoxidation process was analyzed and the rate controlling steps were identified. These experiments were also conducted at different temperatures to evaluate the effect of temperature on the deoxidation kinetics.

Jan 1, 1994