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By Ahmad-Bitar¸ Riyad N., Shadia J. Ikhmayies

"CdSi-xTex thin films with O<x<0.3 were prepared on glass substrates by the annealing of CdS:In thin films produced by the spray pyrolysis technique. The annealing was performed in nitrogen atmosphere at 400 --,C in the presence of Te vapor. The compositions of the films were determined by energy dispersive X-ray detection (EDAX) measurements. Scanning electron microscopy (SEM) was used to investigate the morphology of the films. The transmittance of the films was measured at room temperature in the wavelength range 400-1100 nm and used to produce the absorbance of the films. The first derivative of the absorbance was used to estimate the optical bandgap energy Eg by using the minima in the first derivative. The relation between the bandgap energy and the fraction x was found to fit with a parabola and bandgaps in the range 2.196: =Eg: =2.480 e V were obtained. Urbach tailing in the bandgap was also investigated.IntroductionPolycrystalline thin film CdS/CdTe solar cells are promising candidates for low cost and high efficiency photovoltaic applications. The fabrication process of these cells involves the deposition of a p-type CdTe absorber layer on top of an n-type CdS one which acts as a window. The efficiency of the solar cell is affected by the method of preparation of both layers [1, 2].Interdiffusion processes taking place at the CdS/CdTe interface have largely been realized to significantly affect the device performance [3] by changing the bandgap of both CdTe and CdS which modifies the spectral response of the solar cell [ 4]. The formation of a mixed crystal or a graded layer causes a reduction in the lattice mismatch at the CdS/CdTe junction [5] which is about 9% [ 6] and then a reduction in the number of interfacial states and recombination centers, thus enhancing the solar cell performance [7, 8]. A complete understanding of the properties of the intermixed layers CdSxTe1-x that usually constitutes the interfacial region in the CdS/CdTe solar cell is essential. According to our knowledge, a lot of research was devoted to the investigation of the diffusion of S into CdTe [3-5, 9]; but little on the direct investigation of the diffusion of Te into CdS [6]."

Jan 1, 2011

By N. Menad

. Electronic wastes are heterogeneous mixture, with mainly copper, aluminium and steel attached to or mixed with various types of plastics and ceramics. In general, small amounts of precious metals are incorporated in this mixture. Today, these components constitute an environmentally problematic fraction in disposal. Their physico-chemical characteristics have been investigated through chemical, x-ray diffraction, infrared spectroscopy, scanning electron microscopy and thermal analysis.

Jan 1, 2000

By Bhagyadhar Bhoi, Chitta Ranjan Mishra, Pravas Ranjan Behera

Red mud of Indian origin contains around 55% plus of Fe2O3 and is considered as a hazardous waste for the alumina industry. For production of one tone of alumina employing the Bayer’s Process, around two tones of red mud is generated from three tones of Bauxite. Conventional process of steel making is not devoid of environmental pollution. In the present investigation, efforts have been made to produce steel from red mud by adopting reduction roasting, magnetic separation and hydrogen plasma smelting route. Magnetic fraction, containing enriched iron oxide and minimal content of alumina, is produced following the first two stages which is then subjected to hydrogen plasma smelting process for production of steel. This novel concept follows a green path way for production of steel free from pollution and is termed as green steel. Further, the only by-product that is produced in the process, is water, which is eco-friendly and recyclable.

Jan 1, 2015

By Yuanbo Zhang, Ruijun Wang, Qian Li, Zhao Jing, Guanghui Li, Zhengwei Yu, Chen Liu

The high content of sodium and potassium in sinter is harmful for blast furnace ironmaking. Reductive sintering technology can remove more alkali metals than conventional sintering process. In order to improve the removal ratios of Na and K, reductive sintering with both CO-containing flue gas circulation and carbon-bearing pellet was conducted in this study. Experimental results show that all indexes except the VSV and P were improved in reductive sintering with CO circulation. Flue gas circulation technique combined with carbon-bearing pellets were beneficial to reductive sintering, because it could maintain good sintering indexes and enhance the removal of Na, K. The best removal ratios of Na, K and reduction degree of iron oxides were 20.37%, 63.73% and 23.76%. In reductive finished sinter, silicate mineral becomes the important binder phase, and main iron mineral phases are wustite (FexO) and magnetite (Fe3O4).

Jan 1, 2016

By Peng Jianping, Feng Naixiang, Di Yuezhong, Wang Yaowu, Pan Xijuan

A vacuum silicon thermal reduction lithium process is developed in present work which used lithium hydroxide, alumina and calcium oxide as raw materials. The process contains two steps, which are that Li5AlO4 clinker is prepared in ambient environment, and that metal lithium is extracted from Li5AlO4 clinker with ferro-silicon alloy as reductant in vacuum. On the basis of thermodynamic analysis and investigative experiments, feasibility of this process is proved. The results show that Li5AlO4 can be generated by calcination lithium hydroxide and alumina, the burning loss is above 31% under the conditions of calicination temperature above 750℃ and time more than 90min. The main phases of calcination product are Li5AlO4 and CaO. When the calcination product is reduced by ferro-silicon alloy in vacuum, the lithium reduction ratio can be over 80% under the conditions of reduction temperature 1200℃ and reduction time 60min.

Jan 1, 2014

By Fumitaka Tsukihashi

Increasing amounts of steel scrap are being used as resources for steelmaking. Therefore. there has been a growing interest in the removal of handful tramp elements such as antimony, zinc, tin, arsenic, bismuth, lead and copper from the molten steel. The problem that should be solved is the economic removal treatment of residual tramp elements in the steelmaking processes and the production of high quality steel by reducing the effect of the contaminated tramp clements and satisfying the environmental regulations. In this paper, the available thennodynamic data of the residual tramp elements in the molten steel are summarized and the possibility of the removal of residual tramp elements from the molten steel is thcnnodynamieally estimated.

Jan 1, 2003

By I. D. Reznik

On blowing nickel matte in a converter without quartz, first the oxidation of metallic iron and a part of FeS occurs without evolving sulfur dioxide, the formed FeO dissolves in a sulphide smelt and form a homogeneous oxysulphide smelt. On further increasing the FeO content, the oxysulphide separates into 2 layers. Based on the laboratory investigation of FeO-(FeS+Fe°) - (Ni3S2+Ni°) ternary phase diagram we have identified the separation region at 1250°C. The boundaries of the separation region have the form of an arc and the composition of the separated oxysulphide layers is defined by the canodes. In the nickel or copper-nickel matte - silicacalcium oxide slag system at 1250°C three layers, namely sulphide, oxysulphide, and slag may be formed. A high slag basicity due to the presence of CaO can serve to enhance the activity of FeO; a low nickel content in the matte corresponds to a high concentration of FeS therein; FeO from slag and FeS from the matte form a homogeneous FeO-FeS solution, i.e. an oxysulphide layer. The investigation on the "Camebaks" apparatus and by the nuclear gamma-ray resonance spectroscopy method of the phase composition in a slowly cooled oxysulphide layer has shown the presence of four phases: wustite, troilite, ferronickel grains, and calcium oxide-silica inclusions. Knowledge of regularities in the oxysulphides formation makes it possible to use them in pyrometallurgy of nickel and cobalt or preventing their formation.

Jan 1, 1997

By Tomás Vargas

The catalytic role of Thiobacillus ferrooxidans in the dissolution of chalcopyrite was studied by leaching pure massive samples of this sulfide with a pure strain of Thiobacillus ferrooxidans (ATCC 19859). Monitoring of the bacterial activity showed that an important fraction of the total bacteria generated during leaching remained attached to the chalcopyrite surface. Bacteria grown in the system, which were the offspring of bacteria adhered to chalcopyrite, was well explained as the result of the utilization of ferrous ion and sulfur as energy sources. The potential for indirect and direct action was fully utilized by the existing bacteria and the leaching process was controlled by the kinetics of chalcopyrite dissolution.

Jan 1, 1990

By Vladimir Mindin

This paper presents results of thermodynamic investigations and experimental&apos; studies of some essential for pyrometallurgy of sulfide concentrates topics. Among them: 1. Thermodynamic simulation and experimental investigations of roasting process, 2. Thermodynamic investigations of sulfur dioxide off-gases treatment technologies. 3. Investigations on "Mind in -Kiknadze" effect of suppression of sulfur dioxide formation during sulfide concentrates roasting in the vapor containing atmosphere. 4. Thermodynamic simulation and experimental investigations of sulfide concentrates and manganese containing materials co-roasting processes. Some essential aspects of thermodynamic simulation techniques are also discussed.

Jan 1, 1998

By Huimin Lu, Shi Zhou, Lisha Yang

"The Zeolitic imidazolate frameworks (ZIFs) were successfully synthesized by applying a combination of ionothermal synthesis and microwave energies for rapid synthesis. The synthesis was proceeded under various conditions including different raw materials, reaction temperature as well as microwave irradiation time. Zeolitic imidazolate frameworks (ZIFs), also known as coordination polymers, are new type of porous materials formed by inerratic polyhedral in three-dimensional. They are the ideal crystalline substances for gas separation and storage. The assynthesized samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), thermal gravimetric analysis (TGA) and C02 adsorption test. Results illustrated that the synthesized samples had stable structure, high thermal stability (up to 530 °C) and C02 adsorption capacity (10.2 cm3/g at 0°C under ambient pressure). This novel method also showed great advantage with high energy efficiency, safe synthesis conditions, and rapid crystallization time (60 minutes).IntroductionNowadays, carbon dioxide capture has become imperative due to the global warming caused by the increase of C02 in the atmosphere, especially produced by the concentrated sources such as power plants [1]. Zeolitic imidazolate frameworks (ZIFs), also known as coordination polymers, are ideal crystalline substances for gas separation and storage due to their structure diversity, high thermal and chemical stability [2-5]. They are formed by inerratic polyhedra in threedimensional with large cages and small apertures. Traditionally, ZIFs are synthesized by solvothermal method in a sealed autoclave under autogenous pressure [6-9]. However, in order to generate the products, the solvothermal temperature should not be lower than 100°C according to the sovlothermal mechanism. Moreover, at such a temperature, molecules with a low boiling point (such as water) may generate high pressure in reactor which might cause danger [9]. Thus the synthesis requires the equipment to possess resistance to autogenous pressure and corrosion. Further, conventional solvothermal methods need a long time to prepare products, usually a few days, which is a large energy consumption and inefficiency. So it is interesting to synthesis ZIFs through other ways under mild reaction condition with high energy efficiency."

Jan 1, 2012

By Flávia Paulucci Cianga Silvas, Otávio da Fonseca Martins Gomes, Viviane Tavares de Moraes, Denise Crocce Romano Espinosa, Jorge Alberto Soares Tenorio, Guilherme Apostólico Bortolini, Stoyan Gaydardzhiev

"Printed circuit boards (PCB) are particularly problematic to recycle because of the heterogeneous mix of organic materials, metals, and glass fiber. PCBs are found in almost every electroelectronic equipment and their recycling process involves a pre-treatment to separate the products which contain targeted metals. In this work, a physical processing involving sequential shredding and hanuner milling were used to obtain a comminuted sample from scrap printers PCBs. The thus prepared sample was analyzed for particle size distribution and by optical microscopy as well was subjected to pyrolysis, leachabilty and chemical composition determination by XRF. The metals concentration was determined by ICP and AAS. The PCBs have been also analyzed by SEM-EDS (micro-analysis and X-ray mapping). The results show that the studied PCBs are lead free, multilayer with 4 copper layers, have 45% of metals and the copper is present in significantly higher concentration than the rest of the metals.IntroductionThe global generation of e-waste (electrical and electronic equipment waste - WEEEs) grows at a rate of about 40 millions of tons per year [ l].Among this e-waste there are PCBs that are present in almost all electronic equipment. Their composition is heterogeneous and varies according to several factors, including: kind of EEE, when and where it was produced, fabrication technology [2], etc. In printers, the PCBs represent about 6.6- 8 wt.% [3].The PCBs treatment may include physical, pyrometallurgical, hydrometallurgical, ectrometallurgical and more recently bio-hydrometallurgical process. Normally there is a combination between these processes [2, 4, 5, 6, 7, 8, 9, 10].The diversity between the different PCBs composition complicates the recycling process since the composition of metal and others materials can vary according to the models. So characterization is an indispensable step before any processing of PCB to begin. Owing to the above said, the main goal of this work has been set to characterize representative samples of PCBs from printers through physical, chemical and microstructural analyses."

Jan 1, 2014

By Zhang Yongzhu

Developments on bioleaching of low grade ores and refractory gold ores by T. Ferrooxidans in China are summarized. Effect of the ions on bacterial growth, bioelectrochemical reaction mechanism of sulfide minerals and bacterial reaction mechanism are also discussed.

Jan 1, 1992

By Zhenjun Tan, Lei Zhang, Jigang Li, Yifang Zheng, Jilai Xue

"Water electrolysis in 0.4 mol/L NaOH solution for hydrogen generation was carried out with ultrasound introduced through the anode. It was found that the cell voltage reduced by 150-300 mV in the current range of 20 mA to 40 mA with ultrasound frequency at 25.3 kHz. The cell operation became unstable when the cell current was larger than 75 mA with ultrasound. This reduction in cell voltage was due to removal of the gas bubbles on the electrode surface, which can be directly observed in the see-through cell of water electrolysis. Ultrasound with frequency of 33.3 Hz was also tried, but no better effect was obtained. The results suggest that ultrasound assisted water electrolysis can have potential in energy savings for hydrogen production.IntroductionIn electrolytic process, the electrode that the bubbles generated on its surface usually covered a thin gas film, which can be caused an additional voltage about 0.15-0.25V[l,2], especially in aluminum electrolysis. To solve the problem, loading the ultrasound removes the gas bubbles from the electrodes, this subject had been researched in recent years. From 1995 Jilai Xue et al[3,4,5]. applied the ultrasound in aluminum electrolysis in lab. The results from Sheng-De Li et al.[6] reveals that can decrease the cell voltage and have influences about the hydrogen and oxygen's output ratio. Although there are many paper about the applying of ultrasound such as in electrolysis[5,6], deposition[7,8], plating[9,10], oxidation of salts substance on the surface of electrodes[l 1] and so on, the effect of different frequencies ultrasound hadn't been investigated deeply.We focus on the anode voltage by different frequencies ultrasound and the bubble behaviors in this paper. The environment of this experiment is in alkaline solution. Through this exploration it can offer a basis for the applying of ultrasound in electrolysis."

Jan 1, 2011

By N. Y. Ma

Solid wastes produced in ironmaking and steelmaking off-gas cleaning systems often contain zinc. The zinc level in these solid wastes is generally too high to recycle the wastes for iron through blast furnaces, but too low to economically treat the wastes for zinc through zincrecovery facilities. The behavior, status, and distribution of zinc in the ironmaking and steelmaking off-gas cleaning systems have been analyzed from three aspects: thermodynamics of zinc condensation, oxidation and deposition, correlation of zinc concentration with particle size and density, and aerodynamics of dust particles in the off-gas cleaning systems. Theory and supporting data show that spontaneous separation of zinc from iron-bearing dust occurs in the ironmaking and steelmaking off-gas cleaning systems. Dry off-gas cleaning systems provide the most favorable conditions and environments for zinc to separate from the dust. If highefficiency dry separators were applied and appropriately arranged in the off-gas cleaning systems, zinc would be concentrated, and the majority of the solid wastes could be recycled for iron recovery through blast furnaces.

Jan 1, 2008

By J. M. Boxall

The electrolytic zinc plant at the Bartlesville division of Z.C.A. originally used lead anodes containing only 0.25% silver because only H.G. zinc and alloy was to be produced. In 1984, a small addition of strontium carbonate was made to control the surf ace morphology of the cathodes which reduced short circuits and increased current efficiency. Later a drastic reduction in colloid addition further reduced short circuits. Increased strontium additions allowed the production of some S.H.G. zinc. Increasing the silver content of the anodes reduced the lead in cathodes only slightly. More important, the anode scale that was not removed during anode cleaning, entered the electrolyte and contaminated the cathodes with lead. A piping system has been installed to purge the contaminated electrolyte directly back to the leaching section. This has allowed the plant to produce S.H.G. zinc consistently.

Jan 1, 1990

By Zhucheng Huang, Ronghai ZHONG, Liangming Wen, Tao Jiang

The reduction roasting-magnetic separation and its strengthening of high silicon coal-containing mini-pellets by sodium additives were researched. The results show that the carbon gasification reaction and reduction of fine hematite in high silicon coal-containing mini-pellets with 3% sodium additives were enhanced. Comparing with no sodium additives, the gasification rate of carbon with 3% sodium additives reacting with CO2 for 40 minutes at 950 and the metallization rate of reduced pellets with 3% sodium additives after roasting for 35 minutes at 960 increased from 35.15% and 58.72% to 86.98% and 86.15%, respectively. The analysis of SEM equipped with EDS demonstrates that the inner pore of reduced pellets with 3% sodium additives was more developed and the iron grains size significantly enlarged, meanwhile, the iron grade of concentrate increased from 60.45% to 80.23% and the iron recovery rate decreased from 84.67% to 80.78% after grinding-magnetic separation.

Jan 1, 2016

By Min Chen, Lei Xu, Weijun Huang, Shuai Zhang

For the purpose of extending the service life of MgO-C bricks used as linings of vanadium-extraction converters, the effect of Fe addition on properties of MgO-C bricks was investigated. The results showed the addition of Fe could effectively improve the sinterability of the oxidized layer of the MgO-C refractory at 1400°C due to the effect of FeO (formed by oxidation of Fe) on formation of MgO-FeOss and modification of the microstructure, and excellent corrosion resistance against vanadium containing slag was also obtained due to the increase of compactness of the oxidized layer and concentration of FeO in the oxidized layer. Consequently, it is considered that MgO-C brick by introducing the new phase of Fe is a favorable substitute of MgO-C refractory to be used as linings of vanadium-extraction converters.

Jan 1, 2015

By Run-bo Wang, Zhe Wang, Fan-yi Meng, Jian-Liang Zhang

The influence of semicharcoal substitution for coke breeze on sintering performance was investigated by pot-grate sintering test. At a fixed fuel ratio, sinter productivity and strength decreased with the substitution increasing from 0 to 100% due to better combustibility. To enhance the utilization efficiency of 100% semicharcoal, sintering parameters (moisture and suction pressure) was adjusted. With the moisture increasing, sinter performance of 100% semicharcoal increased because of the suppression of semicharcoal incomplete combustion. As the moisture further increasing to 9.0%, sinter quality gave rise to a decrease trend. The results also showed that the increase of suction pressure was benefit for the increase of heat transfer rate, leading to the improvement of heat utilization energy. Measures to enhance magnetite oxidation during sintering are discussed based on current understanding of the fundamentals that control the sintering process.

Jan 1, 2015

By Tao Zhang, Wen-tao YU, Hai-bin ZUO, Jian-Liang Zhang

Sintering-pot tests and metallurgical performances of sinter with 4 kind of different Al2O3 contents are experimented in this paper. Results show: when the Al2O3 contents increase from 2.0% to 3.5%, acicular calcium ferrites in mine phase will be gradually replaced by plate-like iron calcium. The increase of Al2O3 contents will lead to the addition of liquid viscosity and the reduction of permeability of sinter bed. Sintering time will be prolonged. The rate of yield is stable basically but production is low; besides, the increase of liquid viscosity will decrease of drum strength. The change of permeability of the material layer will make RDI +3.15 decrease first and then increase when Al2O3 contents changed from 2.0% to 3.5%. RI of sinter shows a contrary trend because many open voids are formed by deterioration of liquidity first and then pores closed.

Jan 1, 2015

By M. Misra

The removal of lead and other heavy metals present in an active US Army small arms firing range soil was evaluated in a pilot scale test program at Ft. Polk, Louisiana. Two different acid based extraction processes in conjunction with conventional physical separation methods were used. Physical separation processes consisting of screening and gravity operations removed most of the coarse lead particulates and slugs. Hydrochloric acid leaching followed by precipitation of lead as hydroxide recycled clean soil containing less than 500 mg/L. total lead and less than 5 mg/L TCLP lead. Lead extraction efficiency with hydrochloric acid was 96 percent. The results of lead removal by physical separation in conjunction with acetic acid leaching were not consistent over the whole test period and the total soil processed.

Jan 1, 1998