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By Shaohua Ju, Feng Jiang, Chuanhua Li, Jinhui Peng, Libo Zhang

A T-junction microchannel is proposed to overcome the existing problems in conventional solvent extraction of indium from zinc hydrometallurgical process. Experiments were performed to separate In3+, Fe3+ and Zn2+ from sulfate solutions using Di-(2-ethylhexyl)phosphoric acid (D2EHPA) as the extractant. The effect of parameters such as pH, microchannel size and contact time on the extraction behavior of In3+, Fe3+ and Zn2+ was investigated. At contact time of 2.52 s and initial solution pH of 0.48, the extraction efficiency of In3+, Fe3+ and Zn2+ was 99.13%, 8.31% and 2.45%, respectively and separation factor of In3+/Fe3+ and In3+/Zn2+ were almost 1229.54 and 4864.98, respectively. Then, the loaded organic phase was stripped in T-junction microchannel. At contact time of 33.6 s, 99.64% of stripping efficiency of In3+ and stripping equilibrium were reached, while concentration of Fe3+ and Zn2+ was lower than 0.01 g/L with good separation of In3+ from Fe3+ and Zn2+.

Jan 1, 2016

By Maribel L- Saucedo-Muñoz, Toshiyuki Hashida, Victor M. Lopez-Hirata, Shin-Ichi Komazaki

"Small-punch tests were conducted at 4, 77 and 293 K on three types of austenitic stainless steels JNl, JJl and JK2, which were solution treated, water-quenched and then aged at 923, 973, 1023 and 1073 K for 5 h. Small-punch test energy was employed for the evaluation of the aginginduced embrittlement behavior in these materials. Fracture surface of small punch test specimen for the solution treated steels exhibited a ductile fracture, showing the highest SP test energy values. The presence of intergranular brittle fracture was observed in aged specimens. Smallpunch test energy decreased significantly as the aging process progressed. The highest and lowest decrease in small-punch test energy with aging temperature occurred in JNl and JK2 steels, respectively. The decrease in small-punch test energy showed to examine appropriately the aging-induced embrittlement in these materials. The difference in aging-induced embrittlement behavior for these steels was explained based on the volume fraction of intergranular precipitates in aged samples.IntroductionA high level combination of strength and toughness is required for cryogenic structural materials used in the superconducting magnets of fusion nuclear reactor. This requirement is beyond the capability of conventional austenitic stainless steels [1]. The Japan Atomic Energy Research Institute (JAERI) developed new cryogenic JNl, JJl and JK2 austenitic stainless steels. The structure of superconducting magnets is supposed to be constructed by welding thick plates of this kind of steels. Thus, most of the components are exposed to thermal cycles. The slow cooling may cause microstructure changes in both the base material and weld zone. These changes may also decrease the fracture toughness of these materials at cryogenic temperatures. Therefore, it is important to study the effect of thermal aging on fracture toughness behavior for these steels. Konosu et al. [2] carried out a study of the effect of thermal aging on the mechanical properties for JNl steel using tension and fatigue tests. Kwon et al. [3] evaluated the deterioration in fracture toughness at cryogenic temperatures for the isothermally aged JNl steel by means of the Small-Punch (SP) test. No other reports were found about the cryogenic fracture toughness behavior for this kind of steels. To evaluate the cryogenic fracture behavior, the elastic-plastic Jrc value is a good alternative [4,5]; nevertheless, the standard required specimen size makes it difficult to be used for the fracture toughness evaluation in small zones."

Jan 1, 2011

By Adolfo Pillihuaman, Alberto Nogueira, Cyro Takano, Marcelo Mourão

The organic household waste has a growing disposal problem, requiring costly disposal systems. It is necessary to find new applications for these materials; one could be the steelmaking raw material production. In this paper is studied the development of self-reducing pellets from the organic waste pyrolysis, where is generated carbon and condensable and non-condensable volatiles. Non-condensable volatiles were burned and condensable volatiles were recovered. The resulting tar was mixed with iron ore, coal powder and flux (CaO), to then be pelletized together. Compression, falls and tumbler tests were conducted to characterize the pellets before and after heat treatment and reduction processes. The reduction curve and their physical and morphological characterization were measured. The results were as was expected, the fluidized coal create sufficient adhesion that pellets earned resistance with an equivalent resistance of common pellets, showing a good feasibility of this process.

Jan 1, 2015

By Chi-Ming Chang

Alloy powders are commonly used in the purification of zinc sulfate solutions for use in standard electrowinning practice. The primary goal of this research was to study the use of zinc-lead alloys for similar reactions in the galvanic stripping of impurities from organic solutions. The effects of various parameters on the electrochemical behavior of commercially produced zinc-lead alloy powders were determined. A qualitative evaluation and summary of the influence of the more pertinent parameters on iron removal from di-(2-ethylhexyl) phosphoric acid (D2EHPA) by galvanic stripping is given. Water concentration, oxygen content and reaction temperature were the principal factors affecting the reaction rate and process efficiency. Activation energies were also calculated and indicated that the reaction changes from chemical to diffusion control .with increasing temperature in the range of 35" to 45°C. The results showed that zinc-lead alloy gave faster reaction rates with less sensitivity to process variables than SHG zinc as a reducing agent for galvanic stripping. The role of lead could be as cathodic sites for the reaction which enhances the zinc dissolution or anodic half reaction. The morphology of the zinc-lead alloy surfaces, before and after the reactions, supports this assumption.

Jan 1, 1998

Direct electrowinning is an electrochemical process which has been developed for the extractive recovery of copper from dilute, acidic leach solutions. In passing through a thin particulate coke cathode. copper is reduced and electrodeposited in a thin layer forming a solid copper-coke sheet. The product is melted in a furnace to separate the coke, then the molten copper is fire refined to produce a salable product. A description is given of a prototype unit which is designed to treat 20 gpm leach liquor and recover over 100 pounds of copper per day. Economic analyses show that in a commercial facility producing about 25.000 TPY copper.*the direct electrowinning process has lower overall cost than either conventional iron-cementation or the newer liquid ion exchange-electrowinning when the leach liquors contain less than 2 grams per liter of copper.

Jan 1, 1976

By Gaifeng Xue, Xiaohong Xu, Meng Liu, Yijie Song, Guotao Xu, Jixiong Liu

BN (Boron Nitride) based composites were prepared with hot-pressing by using h-BN as main material in ceramic preparation process. The relative density, bending strength, vickers’ hardness, thermal shock resistance, thermal expansion coefficient, thermal conductivity, phase composition and microstructure were tested and analyzed by using modern testing technology. The results indicate that the best formula is B, the relative density is 97%, the bending strength is 260 MPa, the hardness is HV5 343kg/mm2, the thermal expansion coefficient is 2.8×10-6℃-1, the thermal conductivity is 22 W/(m.K) and have no crack after thermal shock for 20 times by water cool. XRD analysis indicates that the main phase compositions are h-BN, β-Si3N4 and sialon. SEM studies show that the grains wrapped up by solid solution.

Jan 1, 2015

By Merete Tangstad, Ragnar Tronstad

Ferromanganese production in electrical furnaces is quite an old process. However, as the furnaces are getting bigger, the requirements of cost, yield, product quality, emissions and security are raised. With the increased expectations, the fundamental knowledge must follow. Within the last 25 years there has been a great effort both in the industry as well as the academic environment to push the limits of this process. This article will show some examples of improvements within fundamental data, reaction mechanisms and emissions over this time period.

Jan 1, 2014

By Leonard J. Friedman

There have been considerable changes in systems, equipment design and materials used in the modern Sulfuric Acid process. Many of these will shape the metallurgical sulfuric acid plant for the year 2000 and beyond. Advances have come from all over the world, and include new scrubbing area designs, catalyst contacting devices, silicon stainless alloys for unlined acid systems, energy recovery from acid heat, stainless converters and heat exchangers, etc. This paper describes each of the process "advances" and presents a review and analysis indicating advantages, operating experience and limitations.

Jan 1, 1988

By Roderick Guthrie

Gas injection into liquid steel baths is widely practiced, ever since the early days of Bessemer’s pneumatic steelmaking process. What has not been fully appreciated is the critical role of bubble sizes for delivering higher quality commercial steels than is presently possible. This was first proposed by Prof P. Hayes and his research group. Using a full-scale water model of a typical 4-strand Ladle-Tundish-Mold system, we demonstrate the potential advantages of modifying a typical ladle shroud, to generate microbubbles within the water flowing into the tundish. This is possible by taking advantage of high shear rates and turbulence kinetic energy available in that region. These microbubbles enhanced the removal of “micro-inclusions” (hollow glass microspheres) in the 5–50 micron size range, to the upper surface of the tundish. There, they were absorbed into an overlaying “slag” phase. Accompanying CFD studies confirmed that no microbubbles in the size range generated (500–900 μm), pass through the submerged entry nozzles into the moulds.

By Marc Verhaege

The effluent under investigation results from a catalic oxidation unit in which paraxylene is oxydised to terephtalic acid. The solution contains cobalt and manganese as their acetates in a concentration range of 0,4 - 1,2 g/I of cobalt and 0,8 - 2,4 g/l of manganese. Before being fed into the main waste stream treatment unit of the plant it is advisable to apply a petreatment step in which both metals are eliminated to a great extent from this effluent. Conventional treatment is done by precipitation of both metals either through pH increment with a base or by adding a suitable reagent producing insoluble species. The aim of this study was to look for a treatment (elimination of both metal species) in which no sludge or precipitate is formed.

Jan 1, 1995

By Douglas M. Matson, Rongbiao Gu, Christopher San Marchi, Anil Saigal

"Hydrogen embrittles most structural metals, although the form and magnitude of embrittlement depends on the source of the hydrogen as well as the stress in the metal. Hydrogen fuel cell systems typically store gaseous hydrogen fuel at high-pressure, which provides both a source of hydrogen and high stresses in the containment materials. Understanding and measuring the effects of hydrogen on the mechanical properties of common structural metals, especially fatigue properties, is important for safe, long-term operation of such systems. This work explores the use of thermography to efficiently and quantitatively evaluate hydrogen-assisted fatigue of type 304 austenitic stainless steel. In particular, thermographic analysis was used with rotating-beam fatigue testing and shown to provide repeatable results which are in general independent of test cycle frequency while reducing test times by several orders of magnitude. The effects of hydrogen were studied by thermally precharging fatigue test specimens in gaseous hydrogen prior to thermography-assisted fatigue testing and then compared to testing of non-charged specimens. Hydrogen-precharging increased the strength of this type 304 austenitic stainless steel and increased the fatigue life by a factor of about 50-100.IntroductionThe world is facing a severe energy and environmental challenge: how to provide competitive and clean energy for its citizens in light of an escalating global energy demand and concerns over energy supply security, climate change and local air pollution. As a carbon-free energy carrier, hydrogen provides a promising vector for storing and distributing renewable energy. Hydrogen is an important industrial gas that is used extensively in many industries. However, with growing demand for clean energy, hydrogen fuel cell systems are being developed for use in consumer products, such as fuel cell vehicles, which changes the landscape for safe design of high-pressure gaseous hydrogen systems."

Jan 1, 2012

By Pinakin Chaubal

The campaign life of a modern blast furnace depends on hearth wear. Distributions of liquid iron flow and refractory temperatures have a significant influence on hearth wear. A 3-D comprehensive CFD model has been developed specifically for simulating the blast furnace hearth. It includes both the hot metal flow and conjugate heat transfer thorough the refractories. The model has been extensively validated using measurement data from actual blast furnaces. Good agreements between measured and calculated refractory temperature profiles haven been achieved. It has been used to analyze the velocity and temperature distributions and wear patterns at different furnaces and conditions. The results can be used to point out the directions for protecting the hearth.

Jan 1, 2006

By Yuanbo Zhang, Yingming Chen, Zijian Su, Bingbing Liu, Jun Chen

Iron, tin-bearing tailings is a kind of hazardous solid waste generated from cassiterite dressing operation. It is difficult to utilize the tailings by present mineral processing methods due to the complex dissemination characteristics. In this study, a process of gas-based magnetizing roasting followed by magnetic separation was studied for separating and recovering iron from the tailings. The effects of roasting and magnetic separation parameters on the recovery of iron were systematically investigated. The optimum parameters were proposed as follows: CO/(CO+CO2) content of 5%, roasting temperature of 850 C, roasting time of 60 min, grinding particle size of 90% less than 45 μm and magnetic field intensity of 800 Gs. Under these conditions, the magnetic concentrate containing 68.5% Fe and 0.06% Sn was achieved, which can be used as high-quality raw materials for direct reduction iron production.

Jan 1, 2016

By Hongmin Zhu, Kai Huang, Shuqiang Jiao

"Garlic peel was used as the raw material to synthesize the biosorbent for the selective recovery of precious metals from the acid chloride solution. Garlic peel is rich in carboxyl-, amino- and thiol-groups, has the potential of exhibiting high affinity to Au(III) when appropriate chemical modification process was employed. Here in the present study, the biosorbent was prepared by cross-linking garlic peel particles with concentrated sulfuric acid. Adsorption tests for mixing different metal ions such as Au(III), Fe(III), Cu(II), Ni(II) and Zn(II) from various concentrations of hydrochloric acid media indicated that Au(III) was selectively adsorbed on the cross-linked garlic peel gel over the other coexisting base metal ions investigated. The crosslinking mechanism and selective adsorption of Au(III) were also investigated briefly.IntroductionPrecious metals are quite popularly applied in the modern industries such as jewelry, electronics and electrical devices, catalysts in chemical industry, etc. While their high values, limited deposit and quite large demand in industry makes its recovery from the industrial wastes, typically e-wastes, quite necessary. Actually, many techniques have been developed to recycle and recover the precious metals from various industrial wastes effectively in last decades, but the cleaning and ecofriendly processes are still seriously scarce [1]. Taking into account of the typical recovery processes using cyanide lixiviant in the alkaline media, or aqua regia, followed by the further recovery process using activated carbon adsorption or cementation with zinc, iron or aluminum plate or powder, though they both are quite effective recovery processes, if considering the special requirements on safety and ecofriendliness for the modern hydrometallurgical processes, various improved or novel extraction processes are greatly demanded [2]. Recently, the biosorption technology applied to the recover precious metals in the hydrometallurgical process has become a concern [3,4]. Inoue’s research group made great progress in the recovery of precious metals such as gold, palladium and platinum from the e-wastes such as spent mobile phone by using biosorption from the hydrochloric acid media [5,6]. This new hydrometallurgical process exhibits the prominent advantages of being cost-effective for its short process, easy operation and near-zero emission. In the above recycling process for e-wastes treatment, the preparation of biosorbents is the key and backbone of the whole recovery process. For this purpose, they developed a series of suitable sorbents for precious metals recovery by using the tanning-based or cellulose-based biomass such as persimmon peel, grape peel, orange juicing residue, waste cotton, waste paper through the crosslinking process with concentrated sulfuric acid and relative chemical modification processes [7-10]. In the present study, we also applied this technique to prepare the biosorbent of precious metal uptaking by using garlic peels as the raw materials, and investigated the adsorption properties of such-obtained gel in the hydrochloric acid media."

Jan 1, 2012

By D. G. C. Robertson

The thermodynamics and kinetics of the reactions involved in fuming zinc from oxide slags using coal or coke were first studied in 1955 and have been the subject of many investigations since that time. The key reaction is ZnO(in slag) + CO Zn(g) + COl. This paper will review the some of the recent work, and will add new insights obtained in experiments carried out by the authors. In the first series of experiments it was shown that the reaction 2Fe2+ + ZnO = 2Fe3+ + Zn(g) or 2FeO + ZnO = Fe2O3 + Zn(g) does not occur at an appreciable rate, as is expected from thermodynamic considerations. In the second series of experiments it was shown that zinc does not fume from the slag at a significant rate unless a reductant has been added. This again is in accord with thermodynamic considerations, but is in contradiction to some of the experimental results reported in the literature. A third series of experiments was carried out with excess coke being present, so that the rate of supply of reductant was not in any way controlling the rate. The kinetics of zinc oxide reaction were then found to be independent of the zinc oxide concentration, but increased with increasing basicity, and temperature. The presence of high concentrations of FeO in the slag also improves the kinetics. At low zinc oxide concentrations iron oxide reduction occurred in parallel with zinc oxide reduction. We propose that (under the conditions of this work) the kinetics were controlled by a chemical step, namely the rate of desorption of an adsorbed CO2 species. This is the same mechanism as reported by Belton and co-workers for the kinetics of the reduction of FeO. This explains why the reduction of metal oxides in slags by hydrogen is often faster than by CO.

Jan 1, 2003

By James E. McNulty

Today's energy era is the beginning of a transition from the Petroleum Age to a future age of renewable fuel resources. Fuels for the transition era will come from unconventional sources and conversion technology. Affecting the practicability of transition technologies are attitudes of the public, capital requirements and availability, patterns of fuels utilization, producibility of fuels and the actions of governments. Primary energy sources to replace deficiencies of oil and gas and provide growth in the period of transition will be coal, oil shale, nuclear energy and peat.

Jan 1, 1981

By S. Mattlgod

Self-assembled monolayers on mesoporous supports (SAMMS) have been developed for the removal of heavy metals and some transition metals. The thiol functional groups were assembled on the internal and external surfaces of mesoporous silica with a uniform pore size of about 55 A. The mesoporous supports provide high surface area (>900 m2/g) needed for high metal loading in chemical separation. Self-assembled monolayers of organic molecules bond to the ceramic substrate with prescribed densities, and with terminal functional groups for excellent molecular selectivity. The unique characteristics include: (1) High metal absorption capacity, up to 3.2 mmol/g of SAMMS. (2) Fast Hg-binding kinetics (reducing mercury concentration from 0.5 ppm to 0.5 ppb in less than 5 minutes). (3) High selectivity in the presence of a range of cations, anions, and organic species. (4) Applicability in both aqueous and non-aqueous solvents. (5) Flexibility in surface chemistry. The materials can be designed to adsorb heavy metals, transitional metals, and radionuclides. (6) Chemical stability, and potential for regeneration or waste storage. This paper discusses the results on mercury adsorption.

Jan 1, 1999

By Yun Soon Han, Joo Hyun Park

Indium (In) solubility in the FeO-SiO2-Al2O3-5%CaO slag was measured under p(O2)=10¯¹¹ atm at 1573 K to clarify the dissolution mechanism of In in FeO-bearing metallurgical slag. The In solubility increased with increasing oxygen partial pressure, whereas it decreased by increasing the activity of basic oxide, viz. FeO. Thus, a dissolution mechanism of In in the FeO-SiO2- Al2O3-5%CaO slag was described by the following equation. In(s)+1/4O2(g)=(In+)+1/2(o2-) The enthalpy change of the In dissolution reaction was negative, indicating that the dissolution reaction was an exothermic reaction. This is consistent with the above reaction mechanism.

Jan 1, 2014

By T. M. Dreher

The difficulties associated with the operation of a classical rhodium refining process have prompted many attempts to develop a viable solvent extraction flowsheet for rhodium. Recent investigations at McGill University have involved the activation of rhodium prior to its solvent extraction. The role of activation is to convert the aquochloro complexes of rhodium to a form extractable by conventional solvent extraction reagents. In the novel separation scheme identified, chloro complexes of rhodium are converted to bromo complexes, which undergo aquation to a lesser extent, making them more easily extracted. Rhodium is then extracted using Kelex 100, and stripping is achieved by use of a concentrated chloride based solution. Separation of rhodium from iridium is achieved by either prior reduction of Ir(IV) to Ir(III), as the latter is not extracted, or via co-extraction and differential stripping. A conceptual flowsheet for the refining of rhodium using this method is proposed.

Jan 1, 1998

By Ahmadzadegan. Arash, Anil Saigal, Michael A. Zimmerman

"In this study, the rheology of liquid crystalline polymer (LCP) melts through simplified 2-D and 3-D die geometries is simulated using Polyflow™. It is known that rheological properties of LCPs are close to long chain polymers and their directionality is close to those of small molecule liquid crystals (SMLCs). As a result, different rheological models (both viscoelastic and generalized Newtonian) for long chain polymers in Polyflow™ were investigated based on the available capillary rheometer data. By varying the parameters in these models, it is possible to adjust the effect of shear viscosity, normal stress differences and relaxations times on the rheology of the polymer. The free surface of the extrudate coming out of the die is simulated and the amount of die swell for different types of rheological models is compared. This study indicates that the Bird-Carreau model best applies to thermotropic LCP materials as quantified by die swell. Since the rheology of the LCPs affects the orientation of the crystals, the result of this simulation can be further used to predict the orientation of crystallines inside and outside the die.IntroductionAny rod like molecule or crystal tends to orient itself in the direction of shear as it moves within a flow. Since polymers consist of long chains of molecules, they experience the same phenomena when flowing in the melt condition. For most polymers, the molecules change direction and distribute uniformly in space during the solidification. However due to the higher inertia of the crystals in the liquid crystalline polymers, the oriented crystals will keep their order during the solidification and as a result the final product will show anisotropy in material properties."

Jan 1, 2012