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By Carlos Mauricio Fontes Vieira, Sergio Neves Monteiro, Thiago Samarão Motta

This work has as its objective to characterize ceramic bodies formulated with ornamental rock waste and two different clays to produce ceramic paver. Specimens were made by uniaxial press-molding at 20 MPa and then fired at 950 and 1050oC respectively. The determined technological properties were: plasticity, dry bulk density, linear shrinkage, water absorption and flexural rupture strength. The results showed that the type of the clay has strong influence on the properties of interest for heavy clay ceramics. The investigated waste must be incorporated in small amounts to avoid increasing in the porosity of the ceramics.

Jan 1, 2015

By S. Neogy, M. Gupta, D. Srivastava, V. Kain, S. Roychowdhury, R. C. Prasad, G. K. Dey

"Austenitic stainless steels are an important material of construction for Boiling Water Reactors (BWR). These stainless steels are amenable to strengthening by strain hardening. Various deformation modes at different test temperatures and strain become active. In the present investigation type 304LN stainless steel was used in the annealed and strain hardened condition. Thin foils were prepared from gauge section for transmission electron microscope (TEM) investigation after tensile testing at room temperature and at 288°C. TEM investigation reveals that twinning is the major mode of deformation for the tests done at room temperature while dislocation cross-slip is the major mode of deformation at higher temperature. Stacking faults were also observed to a limited extent. The extent of twinning was much higher for the tests done using the rolled material. The formation of martensite in the stainless steel due to straining was investigated by the analysis of selected area diffraction patterns.IntroductionAustenitic stainless steels (type 300 series) are an important material of construction in Boiling Water Reactors (BWR). These stainless steels cannot be heat treated but can be strengthened by cold working [1]. Nitrogen alloying of these stainless steels result in high strain hardening rates and higher strength without any loss in toughness [1]. Stress Corrosion Cracking (SCC) in BWR of these types of stainless steels have been attributed to surface strain hardening and strain hardening ofregions adjacent to constrained weldment [2].The test temperature [3, 4], prestrain [5] and nitrogen level [5] has been reported to affect the deformation mechanism during tensile testing. Byun et al. [3] have reported the formation of martensite, dislocations, stacking faults and twinning during tensile deformation, the extent of each depending on the test temperature. Strain localisation has been reported to occur during tensile deformation in irradiated stainless steels [ 6]. The behaviour of rolled material during tensile testing is similar to that of irradiated material to a large extent [3]. Austenitic stainless steels are low stacking fault energy (SFE) materials in which various types of microstructures have been reported to form during tensile deformation and the strain is also highly heterogeneous in nature in these stainless steels which aides SCC in BWR environment to a large extent [7]. During cold working of austenitic stainless steels second order twinning has also been reported [8]. Knowledge about the deformation mechanisms operative in the strain hardened austenitic stainless steels during tensile testing at different temperatures is essential to understand the material deformation behavior and the present study aims at enhancing the existing understanding."

Jan 1, 2011

By C. S. Griffith

Lithium Australia NL (ASX:LIT) and ANSTO Minerals have been working together since 2015 on the development of halide accelerated leaching for the extraction of lithium from lithium-bearing micas, spodumene and clays. This technology has been termed SiLeach® process. The driving force behind development of the SiLeach® process, initially, was to develop a hydrometallurgical process to extract lithium from micas and spodumene without the need for the energy intensive, high temperature processing conventionally applied to lithium extraction. This driving force remains today and continues to hold promise in realising the value of previously under-utilised lithium resources. A comprehensive understanding of the technology and its applicability to the processing of micas and spodumene currently exists, and the flowsheet has been rigorously piloted. Production of battery grade lithium carbonate has been demonstrate

By Magnus Ek

After the installation of three new converters as part of the recent expansion of the Rönnskär smelter completed in 2000 work continues to further improve the converter operation. The converter upgrade led to an increase in blister copper taps from 150 tons per batch to more than 300 tons. The total cathode copper production increased from 130,000 tons in 1999 to 230,000 tons in 2001, the first year in full production. In recent years focus has been to improve operating practise, maximize the blowing time, extend the converter campaigns hence to reduce the specific brick consumption and improve the converter slag composition.

Jan 1, 2005

By Yong Li, Tao Jiang, Xiangxin Xue, He Yang

"In this paper, we describe the current status and research progress on the utilization of typical industrial solid wastes in China. We propose a creative method called “eco-utilizing wastes” with an aim of both integration and increment but without second-time waste and pollution, in terms of the characteristics of typical industrial solid wastes, such as titanium-bearing blast furnace slag, high-silicon iron tailing and boron-enriched slag as well as oil shale.Situation of Typical Industrial Solid Wastes in ChinaThough mineral resources in China are abundant, most of these are low grade ores. Moreover, the distribution of mineral resources is asymmetric, which causes the increase of cost and decrease of the economic benefit. Over-exploitation of mineral resources results in a large number of solid wastes. The accumulation of solid wastes not only means the waste of valuable resources, but also causes environment deterioration. There exist some problems in the current practice of the disposal of industrial solid waste, such as only emphasizing the final results and causing new pollution and waste [1]. So the research and development of a high value-added method has a high practical relevance to our nation. Based on the present status and research progress of industrial solid wastes in China, a creative new idea and method for eco-utilization of solid wastes is proposed in this paper."

Jan 1, 2012

By Youn-Bae Kang

Evaporation mechanism of S from liquid Fe–C–S alloys at 1873 K was proposed by analyzing available experimental data. It has been known that increasing C content in liquid alloy increases activity coefficient of S ðfSÞ, and it could raise driving force for the evaporation reaction S = S(g). However, experimental data of the evaporation of S in the Fe–C–S alloys could not be accounted for only by considering the increases of fS. In the present study, formation of carbosulfides, CS(g) and CS2(g), was additionally taken into account in order to explain role of C for the accelerated S evaporation. Surface adsorption of S was also taken into account, which retards the evaporation rate of S. An evaporation model equation was formulated. It can be applied to calculate the evaporation rate of S over wider C content (from zero to its saturation to liquid alloy).

By Baozhong Zhao

Laboratory experiments have been conducted on the removal of As, Sb and Bi from molten copper by SF 6 injection. The results showed that the impurities can be removed by SF6 injection in the? sequence of Sb >As >,Bi and the rate of Bi removal is affected significantly by the concentration levels of As and Sb in the copper melt. Analysis of the experimental data indicates that the impurity removal process is under chemical reaction control rather than by mass transfer of impurity through the molten copper phase. On the basis of experimental results, a kinetic model was developed and the order of chemical reaction and the volumetric chemical reaction rate coefficients of impurity removal were determined.

Jan 1, 1996

By Garth James

Bacterial consortia capable of degrading cyanide and metal-cyanide complexes were obtained from gold mine process waters using enrichment cultures. The cultures contained either cyanide, tetracyanonickelate, or ferrocyanide as a sole nitrogen source. Several bacteria were isolated from the consortia, but none of these organisms were capable of degrading cyanide or cyanide-metal complexes at rates equivalent to those of the intact consortia. The consortium from the cyanide enrichment was capable of completely degrading cyanide from an initial concentration of over 100 ppm in less than one day, when cultured using a fed-batch method. Tetracyanonickelate and ferrocyanide were degraded more slowly. Overall, these results demonstrate that bacteria capable of degrading cyanide and cyanide-metal complexes can be isolated from mine process solutions and are capable of significantly reducing cyanide concentrations under appropriate conditions.

Jan 1, 1998

The cleaning of copper containing fayalite slag using a CuFe alloy was studied under an oxygen pressure ranging from 10-7 to 5 X 10-11 atm at 1200º c. The reduction of copper from fayalite slags by Cu-Fe alloys was found to be very effective. For example, at a P 02 of 10-7 atm, the copper content in the slag was reduced from 4.1 to 0.402 wt. percent after 90 min. of reaction time using a Cu- 5.27 wt. percent Fe alloy. The copper reduction rates were found to be independent of P02 in the gas phase when using Cu-Fe alloys which exhibit an iron activity of greater than 0.4. A mechanism for slag c1eaning is proposed based on the concept that the Cu-Fe alloy lowers the oxygen potential of the slag according to Eq.1 1, fol1owed by the reduction of cuprous oxide by wustite as shown in Eq.2. Here X represents element X in the alloy phase while (X) represents the element in the slag phase. The copper and iron transfer behaviour obtained in this study are explained by a ?Stepwise equilibrium model.

Jan 1, 1985

By Krishna Parameswaran

This paper discusses sustainability considerations in primary copper smelting using selected examples of practices at ASARCO LLC, an integrated U.S. primary copper producer. Using the classic Brundtland Commission definition of sustainable development, i.e., “development that meets the needs of the present without compromising the ability of future generations to meet their own needs,” the paper discusses how copper mining and smelting practices can be made sustainable. The examples used to illustrate sustainability considerations include: (1) adoption of flash smelting; (2) emission reduction and process improvement associated with anode refining of blister copper and the converter retrofit project, and (3) preliminary research findings on alkali treatment of copper smelting slags and copper mine tailings.

By Z. B. Moukhametshina

The process of various zirconium alloys iodination by the iodine vapor was investigated. The nature of impurities, conditions of iodination, iodine flow rate, and zirconium tetraiodide condensation rate effect on the metal impurities transfer process was analyzed, both qualitative and quantitative correlations were established. Impurities were classified according their transfer extent. Another classification of impurities transport dependence on iodination process temperature was also offered. Obtained results were compared with impurities transport data in the process of iodide refining available in literature. Some impurities transport mechanisins and iodide-refined metals improvement possibility by means of iodination conditions control were discussed.

Jan 1, 1997

By Jinxing Ji

Several fundamental aspects related to the nickel electrowinning from chloride electrolytes have been addressed in this paper. The thermodynamic study includes the activity coefficient of the hydrogen ion and the speciation diagram of NiCI2 solutions. The activity coefficient of the hydrogen ion (YH+) was calculated and estimated experimentally using a combination glass pH electrode. It was found that YH+ was greater than one in concentrated NiCl2 solutions and increased significantly with increasing NiCl2 concentration. The speciation diagram for NiCl2 solutions was plotted with YH+ and the effect of the ionic strength on the equilibrium constants being taken into account. It was discovered that the predominant nickel species in the acidic region were Ni2+ and NiCI+ in 0.937 M NiCl2 solution at 25°C. Electrodeposition tests demonstrated that higher Nit' concentration in the electrolyte improved the current efficiency of nickel electrodeposition (CENi). The additions of H3BO3, and NH4Cl increased very little the current efficiency of nickel electrodeposition at pH 1.5 and temperature 60°C. However, the addition of sulfate decreased the current efficiency of nickel electrodeposition. Nickel electrodeposition was also found to be a steady-state process since the amount of acid added to the electrolyte at a constant pH increased linearly with time during galvanostatic electrodeposition. The cathode surface pH during nickel electrodeposition was measured using a flat-bottom combination glass pH electrode and a 500-mesh gold gauze as cathode. The cathode surface pH was found always to be higher than the pH in the bulk electrolyte, and if the current density was sufficiently large, it would eventually reach a level causing precipitation of insoluble Ni(OH)2(s) on the cathode surface. Rotating disc electrode studies revealed that the rate of nickel electrodeposition was first order with respect to the activity of nickel ion and zero order with respect to the activities of chloride and hydrogen ions. The rate of hydrogen evolution was found to be first order with respect to the activity of hydrogen ion and to be zero order with respect to the activities of nickel and chloride ions. These findings indicate that nickel deposition and hydrogen evolution proceed independently.

Jan 1, 1995

By Kazuyuki Kakegawa

"Sintered body of lead zirconate titanate (PZT) was prepared through the spark plasma sintering (SPS) technique. When the mixture of raw materials was calcined at 800°C and sintered at 900°C for 10 min. with SPS technique, the sintered body had almost theoretical density but was a mixture of lead titanate (PT) and PZT. When a calcining temperature of 1100°C was employed, sintered body had a single PZT phase but a lower density. High dielectric constant was obtained for a sample calcined at 800°C, sintered with SPS tecbriique and fired again in the air at 1100°C.IntroductionSpark plasma sintering (SPS) is a recently developed technique for sintering metals and ceramics1. The scheme of SPS is shown in Fig. 1. Sample is put in a graphite die in a vacuum chamber. It is pressed and pulse voltage is applied. The electric current heats the die. It is said that the pulse causes a spark-plasma between particles in the sample. Because of the spark- plasma, sample can be sintered at temperatures lower than that in the ordinary sintering by several hundred degrees of Celsius. The sintering period is also very short2Low sintering temperature and short sintering period in SPS technique cause low reaction rate. It is both disadvantage and advantage. In some cases, the reaction cannot be completed under the SPS conditions. If a mixture of several compositions having different properties can be sintered without a compositional change by the diffusion during the sintering, combination of properties, and therefore a design of property will be possible3. The low reaction rate of SPS may enable such combination."

Jan 1, 2000

By Keizo Uematsu, Satoshi Tanaka, Nozomu Uchida, Yutaka Saito

"Effect of moisture content must be fully understood for controlling the granule compaction of ceramics. It changes the mechanical behavior of spray-dried granules applied for compaction process, and governs the structure and properties of .ceramics. To understand the time-dependent change in processing, the kinetics was examined for change of moisture content for granules placed in a die and the pressed compacts also. The results were explained in terms of apparent moisture diffusion coefficients. They varied non-linearly with the PVA content in the granules. The results were explained through the non-uniform PVA distribution in the granules.IntroductionMoisture must be controlled in compaction process to produce the green compacts having uniform structure. It affects glass transition temperature of binder and thus the deformation behavior of powder granules under an applied stress. Several studies [1-7] have clarified the effect of moisture content on the compaction behavior of granules and the structure of resultant compacts for both die pressing and cold isostatic pressing (CIP) of pre-formed compacts. In these studies, the moisture contents in the system were equilibrated with the humidity in the atmosphere before compaction. In practice, however, the moisture content in the system may vary with time if the relative humidity of surrounding atmosphere is different from what the granules were equilibrated previously. This is very likely case in real production processes. However, the kinetics of moisture change in the granules as well as in the pre-formed powder compacts have not been well studied. For controlling the microstructure in a system, it is necessary to fully understand the kinetics of moisture change and its relevance to packing structure of powders."

Jan 1, 2000

By R. Steven Izatt

Green chemistry principles will be discussed, and examples will be given of the use of Molecular Recognition Technology (MRT) to selectively separate specialty metals such as cobalt, nickel, bismuth, rhenium, molybdenum, indium and germanium from various primary and secondary feed streams. Recovery of these metals has numerous advantages including (i) conservation of valuable resources, (ii) prevention of environmental damage, and (iii) elimination of capital and operating expenses due to re-processing or disposal of metal-bearing streams.

By Joël P. T. Kapusta, Romeo U. Pagador, Noparut Wachgama, Chumnoom Khuankla

"Thai Copper Industries (TCI) is a custom copper smelter and refinery in Rayong, Thailand, with an annual capacity of 165,000 tons of cathodes. It employs the El Teniente Technology as the primary smelting reactor to produce white metal from copper concentrates. The white metal is further treated in Hoboken Siphon Converters to produce blister copper then refined in anode furnaces before being cast into anodes for electro-refining in the on-site tankhouse.Thai Copper Industries is the first copper smelter to install and successfully operate on a commercial scale with the Air Liquide Shrouded Injection (ALSI™) Technology in the Hokoben converters with sonic injection of oxygen enriched air and nitrogen for cooling of the injector tip areas. Following commissioning and the establishment of operating practices, the performance of the Hoboken converters with ALSI™ Technology produced outstanding results. The unique combination of an El Teniente and Hoboken siphon converters, both of which are bath smelting operations, offers very high blowing and oxygen efficiencies. As a consequence, reverts recycling was accelerated with minimal build up on the mouth, end-plates or even below the siphon that is typical in Hoboken converters.These outstanding results in the Hoboken Siphon Converters with ALSI™ Technology helped the TCI Plant reach a production of about 75% of its capacity within four months despite the fact that the TCI staff is quite young and its converter know-how and experience are not yet fully developed."

Jan 1, 2009

By Sen-xiang Yang, Xin-teng Liang, Gui-jun Li, Jian-hua Zeng, Yong Chen

"This research is based on PANSTEEL 120t steelmaking converter technology to have the quantitative description of the time needed in uniform mixing of molten steel in the converter with the computer. In present work, the numerical simulation approach is used to analyze oxygen lance nozzle, the flow condition of oxygen and flow status of molten steel in the converter. The various oxygen jet flows that come out from different angles and the flow status of all kinds of jet flows in the converter have also been simulated. All of the simulation parameters are based on the specifically practical conditions according to the physical conditions of PANSTEEL 120 t steelmaking converter. Through numerical simulation, the angle parameter of the oxygen lance nozzle is 16 °. The optimized oxygen lance 536-16 has a good performance in industrial application. This kind of phenomenon shows that the ways and processes of numerical simulation in this research are right.IntroductionThe oxygen lance system is the significant process in semi-steel making converter. It's related to whether the converter or even the whole system can function well. While in actual production, many problems emerge in the process of using the former oxygen lance, such as re-drying, slopping, high lance position, dead burning and even blowing out. In continuous fast-paced process, the unstableness of oxygen lance will lead to speed droop or even stop pouring. Analysis shows that all these problems are not only related to the raw materials but also the design of oxygen lance. Bad oxygen lance's scorification kinetics condition and low content of FeOn in early slag are the direct factors that we cannot easily control in steelmaking at present [l]. Therefore, the good scorification kinetics condition which is related to nozzle has good influence on BOF steel making."

Jan 1, 2013

By Richard A. Heckman

Destructive Thermal Technology (DTT) is used in the management of various waste streams. DTT includes Destructive Distillation, Pyrolysis and Classical Incineration. Recent work has more clearly defined the differences in these technologies based upon a more rigorous thermochemical approach. The U.S. Environmental Protection Agency (EPA) has chosen Classical Incineration as the Best Developed Available Technology (BDAT) for the management of hazardous organic wastes. Municipal Solid Wastes (MSW) and Sewage Sludges (SS) are also managed using Classical Incineration. Three environmental problems plague the use of Classical Incineration. Destructive Distillation, on the other hand, avoids these problems. It is an environmentally benign DTT for managing a wide variety of organic waste streams, including hazardous wastes. Thermochemical analysis of the available data on the performance of three types of DTT will be discussed.

Jan 1, 1994

By Hongbo Zhao, Jun Wang, Wenqing Qin, Guanzhou Qiu, Xueduan Liu

Bio-hydrometallurgy technology was applied for the extraction of copper from the raw ores of Chambishi Mine in Zambia. A copper extraction of 93.29% was obtained for small scale column bioleaching within 63 days, while a copper extraction of 89.05% was achieved for large scale column bioleaching in 90 days, thus confirming the amenability of the raw ores for effective extraction via bioleaching. The bacteria were cultured in a 6-stage enlarge cultivation. The bacterial cultures with cell concentration of more than 1×108 cells/mL were added into a spray pond of sulfuric acid to be applied in the dump leaching, and a copper extraction of about 50% was achieved within 2 months. The production report revealed that the copper extraction increased by approximate 20%, and the acid consumption was reduced to around 35% as a consequence of adding the bacteria. The industrial demonstration of the bio-hydrometallurgy technique is now well established in Zambia, and further applications of bio-hydrometallurgy in both Zambia and Congo are currently in progress.

Jan 1, 2015

By Isabela Leao Amaral da Silva, Felipe Perisse Duarte Lopes, Alice Barreto Bevitori, Sergio Neves Monteiro

"Jute fibers have in the past decades being investigated as possible reinforcement of polymer composites. However, information is still needed on the fiber interaction with a polymeric matrix for a complete evaluation of the capacity of load transference inside the composite. The present work investigated the interaction of jute fibers with polyester matrix by means of the critical length assessment through pullout tests. Tensile tests of polyester sockets embedded with different fiber lengths allowed the critical length to be determined and then the interface shear stress to be calculated. A relatively low interfacial strength was found, which indicates a weak adhesion between the ramie fiber and the polyester matrix. The SEM analysis of pulled out fibers corroborates this result.Introduction Natural fiber, mainly those lignocellulosic extracted from plants, have, in the past few decades, attracted the attention not only of scientists but also of industrial technologists of our society interested in their engineering applications. As it is well known, uses of natural fiber in clothes carpets, baskets, ropes and low cost construction roofing has existed from the beginning of our civilization. Today environmental and energy saving issues are motivating research works on new uses of lignocellulosic fibers in polymer composites [1-6]. Moreover, industrial application of lignocellulosic fiber composites are already in technological sectors such the automobile industry, packing and civil construction [7-9].In addition to environmental, economical and social benefits, some lignocellulosic fibers present specific properties that are comparable to those of other synthetic fiber used for polymer composite reinforcement. For instance, the specific strength (GPa.cm3/g) of curaua (1.31), sisal (0.92) and ramie (0.93) fibers, from results obtained with very thin diameters [10] are relatively closer to that of glass fiber E (1.33). Therefore, in principle, it would be technically justified to replace glass fiber, which is more expensive, toxic and represents a problem to the environment [ll], by a strong lignocellulosic fiber. However, serious drawbacks such non-uniform dimensions and heterogeneous properties [6] as well as the tendency to form aggregates during processing and incompatibility with a hydrophobic polymer matrix, reduce the potential of lignocellulosic fiber to be used as composite reinforcement [1-6]. In particular, a low interfacial strength causes a weak adhesion between the hydrophilic fiber and the polymer matrix."

Jan 1, 2011