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By Youqi Fan

Complicated copper oxalate precursor powder was prepared using ammonium oxalate as precipitating agent in the Cu(II)-C2O42--NH3-NH4+-H2O system. The composition and morphology of the powder are characterized by chemical analysis, X-ray Diffraction (XRD), scanning electron microscope (SEM), infrared spectroscopy (IR). The effects of temperature, copper ion concentration, pH value are investigated. It?s indicated by the experimental results that precursor of copper oxalate is prepared below a critical pH value, whereas the precursor turns to be a complicated copper salt combined with NH3 while over the pH value. Probable chemical formula CuC2O4?x(NH3)?yH2O can be assumed which x and y are relation to experimental conditions. Technological parameters, such as temperature, initial copper concentration and solution pH value, have significant effects on particle size, morphology and dispersion of precursor powder. By controlling certain technological conditions, various morphologies of precursor, pie shape, spindle shape and rod shape can be synthesized.

Jan 1, 2009

By Chuan-fu Zhang

Li(Nil/3Col/3- xMnl/3)MxO2(M=Ti, Mg) cathode materials were prepared from LiOH?H2O and oxalate precursor. The physical and electrochemical properties were studied by XRD, SEM, cyclic volt-ampere (CV), AC impedance and constant current charge-discharge. The results show that crystal volume of Ti4+ or Mg2+ doped sample is increasing and the electrochemical reaction resistant Rct is decreased at high rate, improving the cyclic performance and rate capability. The effect of Ti4+ doped is better than Mg2+. The sample is well crystallized and simple pure phase with a-NaFeO2 layered structure when doping quantity x=0.025. The second specific discharge capacity of Li(Nil/3Col/3- 0.025Mnl/3)Ti0.025O2 is 143.2mAh/g at 1C,128.0mAh/g at 2C in the voltage of 2.75-4.3V,and still has 140.7mAh/g and 121.7mAh/g after 20 cycles, respectively, keeping 98.25%, 95.07% capacity.

Jan 1, 2009

By Jing Zhan

The fibrous precursor can be obtained by coordination precipitation process, using oxalate, cobalt chloride and ammonia. The composition and morphology of fibrous precursor were characterized by XRD, IR, DTA/TGA and SEM analysis. The results show that XRD pattern and composition of the precursor with fibrous morphology precipitated at pH=9.0 were different from that of ß-CoC2O4?2H2O precipitated at pH=1.0. The mechanism on the thermal decomposition of fibrous precursor was addressed. The influences of various conditions in pyrolysis, including the temperature, time, atmosphere, and the morphology of the precursor, on the morphology, average size and specific surface area of the Co powders were investigated in detailed. At last, the final product, fibrous cobalt powders with diameter about 0.3~0.5µm in size and 40~60 in aspect ratio, were produced by thermal decomposition at 400~500? in the weak reducing atmosphere. The structure of pores in cobalt powders was capillary tube with open ports and the majority was mesoporous.

Jan 1, 2009

By Hebi Yin

A coupled cellular automaton (CA) - finite element (FE) model was developed to calculate the growth of dendrites during the solidification of cubic and hexagonal metals. The model solves the conservation equations of mass, energy and solutes in order to calculate the temperature field, solute concentration and the growth morphology of dendrites, including the grain structure and the dendritic microstructure. Validation of the model was performed by comparing the simulation results with calculation results from previously published works, showing qualitatively good agreement in the dendritic morphology. Application to magnesium alloy AZ91 illustrates the difficulty of modeling dendrite growth in hexagonal systems, observed as deviations in growth direction caused by mesh-induced anisotropy. The model was applied to the simulation of small specimens with single- and multiple- equiaxed grain growths and columnar grain growth in directional solidification. The influence of cooling rate and some kinetics parameters on the grain morphology are also discussed.

Jan 1, 2009

By Hua-qing Li

Electromagnetic stirring process effectively improves the casting quality of metals. In this paper, the physical simulation experiment, in which the molten copper is displaced by mercury, was designed. The factory test parameters were determined according the simulated data. The flow behavior of the mercury to be stirred as well as the relations between the microstructure of plate blanks and the current parameters were analyzed. With an appropriate electromagnetic stirring, the inverse segregation of tin for C51900 alloy plant blank reduces from 15 % ~ 30 % to about 5 %, and the proportion of equiaxed grain rises to larger than 30%.

Jan 1, 2009

By Xie Hao

According to its raw materials orthogonal test scheme is designed and a large number of systemic experiments were carried out in order to study the sintering characteristics of three types of fine ores in Kunming Iron&Steel Co.Ltd(KISC). The effects of carbon mixture ratio and basicity on sintering time, agglomeration ratio, physical properties and utilize coefficient were researched via single factor analysis and range analysis. The experimental results show the best mixture ratio of each fine ore. Analysis found that the influence of the carbon mixture ratio is more significant than which of the basicity on the sintering process except agglomeration ratio of foreign ore.

Jan 1, 2009

By Zhang Qin

Dolomite is main impurity mineral in phosphate ores. In practice of phosphate ores production, the grade of concentrates is only containing P2O5 31-32%.In this study, even the increasing of floatation reagent consumption and decreasing of floatation recovery, economic performance is estimated high according to the decreasing of H2SO4 consumption in subsequent production of phosphate fertilizer and the increasing of products value. In floatation stage, influence factor include the synergism impacts of floatation collector, the stages, time, concentration of ore pulp, which were discussed respectively in this paper. Raw material is characterized by mineralogy, chemical analysis, the grain size analysis and milling test . The results show that the grade of concentration can reach to P2O5 36% by deeply de-magnesium oxide from phosphate ores by floatation , which yield a high added value.

Jan 1, 2009

By De-wen He

The distribution of persistent organic pollutants in the environment is studied using the multimedia environmental fugacity model, and environmental health risk assessment of POPs nearby a copper smelt enterprise is carried out. The result indicates that all are in an agreeable risk level without exception. The annual individual chronic risk index of HCB is 7.50×10-11. The annual individual risk index of 3,3',4,4'-TCB is 1.57×10-9, and the annual individual risk index of 2,3,7,8-TCDD is 6.57×10-9.

Jan 1, 2009

By Daoxin Wu

Originated from(C4H9O)4Ti, nano--rutile TiO2 was synthesized by low temperature hydrolysis process in this paper. After being prepared by decomposing ammonium tungstate and covering on the surface of TiO2, TiO2/WO3 were characterized by means of X-ray diffraction(XRD), UV--vis difuse reflectance(DRS), fluorescence spectrum (FS). Results showed that with the increase of the supported concentration of WO3, the reflectance of DRS and the fluorescence spectrum intensity of TiO2/WO3 decreased accordingly, which indicated the powder?s increase in light absorbance and the decrease in luminescence respectively; with the increase of calcined temperature, the reflectance of DRS increased.

Jan 1, 2009

By Elli Miettinen

In Copper Flash Smelting operation disturbances may lead into dust build-up in the gas train and off-gas handling system causing reduced heat recovery efficiency and process availability. Flue dust of a Copper Flash Smelting process heat recovery boiler has been characterized and its thermal conductivity and diffusivity have been determined. Dust accretions consist of several layers possessing varying particle sizes, densities, and thermal properties, with the binding phase usually being sulphate. All the dusts can be regarded as effective thermal insulators with thermal conductivity values of less than 2 W/mK and thermal diffusivity values of less than 0.005 cm2/s. Porosity can be regarded as a fairly good indicator of the thermal transport efficiency of these types of materials, but the material microstructure must also be considered. The results can be used in the dimensioning of metallurgical heat recovery boilers and they also provide accurate input data for process models.

Jan 1, 2009

By Thomas Niehoff, Dave Stoffel

"Energy in the form of natural gas, oil and electricity is expensive and will continue to be a rare resource in the future. Recycling of metals, instead of primary production, is a logical and crucial step towards energy conservation. Energy consumption can be impacted by using advanced combustion systems for metals recycling. Air-fuel combustion has been the conventional method to melt and recycle metals. Global competitive pressures, “greenhouse” gas emissions, and high energy prices force melt shop operations to optimize energy usage and reduce overall operating costs. Oxy-fuel combustion and process technology can be applied to metal recycling operations to meet these objectives. Linde has converted several hundred furnaces from air-fuel to oxy-fuel technology and has extensive experience in optimizing the use of oxygen in furnaces. Additionally, Linde has the process knowledge necessary to avoid costly start-up issues that can accompany the transition to oxy-fuel technology. This paper will describe the benefits and potential issues for conversion to oxy-fuel.IntroductionThe furnace combustion system is the heart of a fossil fuel fired melting process and must be properly matched to the furnace to work as one cohesive unit. Furnaces vary widely in size, shape and features. Rotary furnaces are barrel-shaped and can be designed for tilting or nontilting operation. In a rotary furnace, the products of combustion create a single or double pass through the furnace prior to exiting. Reverberatory furnaces are box-shaped and can also be designed for tilting or non-tilting operation. Reverberatory furnaces are constructed of single or multiple chambers, with or without metal bath movement, and designed for continuous or batch processing. Different furnaces are used for different feedstock materials and products.Furnace combustion systems also vary in many ways. Combustion systems can be of air-fuel or oxy-fuel based technologies, or a combination of the two, resulting in an air-oxy-fuel system. Each of these types of systems has different combustion characteristics which can produce very different results. Here we will describe specific differences in melting processes and their associated energy requirements."

Jan 1, 2009

By A. F. Usov

"The use of the Electric Pulse Discharge method of materials destruction (EP) for disintegration of materials in an industrial-waste processing are examined. The principles and Experience of the development device of EP-disintegration have been described, the technological efficiency of disintegration of industrial minerals estimated.IntroductionThe Russian scientists have proposed and comprehensively studied the electric pulse (EP) technique which is applied in ores and materials disintegration [1, 2 ]. The different aspects of the problem have been presented by the authors in papers at many international congresses [3-6]. Recently the technique is intensively developed in many countries, and various disintegration installations are exhibited.Crashing and disintegration of ores by EP-method is characterized by high selectiveness of destruction. It provides better disclosure of mineral grains and prevent it from destruction. EPmethod reduces slurry formation. All this provides better mineral extraction at ore beneficiation and improves concentrate quality. It also prevents the product from polluting with equipment metal, inwall and grinding equipment material. The possibility to change the character of dynamic loading allows controlling grain-size composition and getting small-size product in contrast to mechanical method of crashing.The product of EP-crashing is characterized by less toughness and greater specific surface area of grains since the new surface is formed at splitting and chinks extension. The product is of high sorption and reactivity in chemical changes. Open grains of mineral spots correspond to their natural condition and it is of great importance for studying mineral.The principles of the development deviceLong-term studies of the technique carried out by research institutes such as Research Institute of High Voltages (Tomsk), Kola Science Centre of RAS (Apatity), Institute ""Mekhanobr"" (S.Pertersburg), made it possible to substantiate principles of the disintegration installations design, make exploratory stands and technological installations to carry out pilot tests and operations under production conditions. The construction design of disintegrating installations depends on many technological and physical factors. Of all the technological factors, the most significant one is to preserve the liberated product because it is the peculiarity of the EPdisintegration to have high selectivity of disintegration. The preservation of the mono-mineral product liberated from the rock mass means that this product is not overgrinding, which causes the loss of the product with slime in processing, and that the initial natural form of the mineral inclusion is also preserved because it is the size and the integrity of crystals that determines its cost value (precious minerals). On the one hand, it is provided by a stage disintegration technique, with the product classified after each stage, and, on the other hand, by selection of specific conditions of electric breakdown, which ensure high performance of electric breakdown and effective disintegration of material fragments, with the useful mineral inclusions preserved intact, with its size considerably exceeding the discharge gap. These conditions are provided by the appropriate geometry of electrodes, the discharge gap and the screen size due to the material’s nature and grain size."

Jan 1, 2008

By Sung-Joo Lee, Gi-Chon Han, Nam-Il Um, Hee-Chan Cho

"In Korea, almost all of bottom ash produced by coal power plants is disposed of in ash ponds. Ash storage areas comprise more than 80% of most coal power plant sites. This disposal method is causing environmental problems and a managerial burden for plant operators. In this study, investigations to develop a beneficiation process for separating coal pond ash into various products were undertaken. To improve efficiency of the separation, coal ash was separated by sizes and each size fraction was subject to various beneficiation processes. The separation process used were flotation (-200 mesh size), hindered settling (16x200) and tabling (16x200 and 8x16 mesh). The results showed that various marketable products, such as lightweight aggregate, sand, high-carbon fuel, could be recovered from coal pond ash using simple physical separation techniques.IntroductionDue to the increased use of coals every year, about fifty million ton of coals were used in 2007 alone. As a result, about 6 million tons of coal ash were generated. In Korea, the coal bottom ash is classified as a general industrial waste and is usually disposed of in ash ponds. The costs for this disposal method continue to increase due to rising costs of site management and development and more strict environmental regulation. Therefore, utilities are constantly looking for ways to increase utilization of coal ash. In this study, various beneficiation processes were evaluated to examine the possibility of separating coal pond ash into various products which can be used as aggregates and high-carbon fuel."

Jan 1, 2008

By Bora Derin, Onuralp Yucel, M. Seref Sonmez, Murat Alkan

"Latest stage in the production of boron carbide by metallothermic methods using magnesium was the leaching process. Boron carbide particles obtained by self-propagating high temperature synthesis contained several impurities such as magnesium oxide and magnesium borates after the metallothermic reactions. Removal of such contaminates by hydrometallurgical methods required to produce high purity boron carbide. Leaching by concentrated hydrochloric acid solutions resulted in the production of pure boron carbide together with high magnesium and boron containing solutions. Removal of such ions from the spent liquor was the necessity to have dischargeable solution. In this study, precipitation of magnesium and boron compounds from relevant chloride containing spent liquors and the production of saleable products was aimed. The effects of chemical reagents, pH of the solution on the precipitation efficiency of magnesium and boron compounds were investigated in the study. Chemical analysis and the characterisationof solid phases by using x-ray diffraction analysis were the latest stage.Introduction A variety of advanced ceramics, inter-metallic, organic and inorganic compounds, oxygen free single crystals, and polymers can be synthesized by using different SHS techniques [1, 2, 3]. In the SHS process, after initiation, reaction becomes self-sustaining and propagates in the reactant mixture. A high amount of heat which is generated during the process accelerates the reaction rate and thus it makes the process highly productive and economically feasible for different production scales. After the SHS process obtained powder mixture needs to reacted with acidic solutions to purify the product. In this case B2O3 was reacted together with C and Mg to synthesis fine B4C powder resulted in the production of MgO as well according to the Eq. 1 and then MgO was removed from the mixture by leaching with the concentrated HCl solution as shown in Eq. 2, respectively [4, 5]."

Jan 1, 2008

By K. Kashiwaya, N. Hiroyoshi, H. Furuya, N. Sumiya, M. Tsunekawa, M. Ito

"The number of hybrid vehicles is increasing and this is causeing an increase in waste nickelmetal hydride batteries. The cathode activating agent of batteries is made of nickel hydroxide and the anode activating agent is an alloy of nickel and rare earth elements. Conventional rotary kiln methods cannot recover the rare earth elements, and hydrometallurgical treatment of crushed product consumes large volumes of agent. The physical separation of the anode alloy from the cathode hydroxide would make it possible to reuse the alloy. The authors have reported separation of anode and cathode components in the large size fractions using a newly developed dry magnetic separation method. Wet magnetic separation has been applied to the powder fraction and about 90% anode purity was achieved. This paper reviews experimental results from previous publications and proposes an integrated treatment process for crushed nickel-metal hydride batteries.IntroductionEnvironmentally-conscious clean energy vehicles have attracted much attention in developed countries and particularly hybrid vehicles are increasingly mass-produced as low emission vehicles. Hybrid vehicles have both a gasoline engine and an electric motor to save on gasoline usage and a nickel-metal hydride battery is used to store electric energy. The battery contains Nihydroxide and Co as the cathode activating agent and an alloy of Ni and mischmetal (mM), a rare-earth element mixture consisting of La, Ce, and Nd, as the anode hydrogen adsorption component. In conventional recycling, the Ni and Fe are recovered with a rotary kiln-electric melting process and the Co and mM go to the slag component [1] and hydrometallurgical treatment of crushed product consumes large volumes of agent. Japan Oil, Gas and Metals National Corporation have proposed a low energy and low cost recycling treatment process combining the physical and chemical treatments and the authors are investigating the physical treatment process."

Jan 1, 2008

By Qixing Yang, Björn Haase, Fredrik Engström, Anita Wedholm

"MiMeR, the Minerals and Metals Recycling Research Centre at Luleå University of Technology, Sweden, started industry-related research work to stabilize an EAF slag from Höganäs AB with of CaO/SiO2 values near to 3.2. The intention was to determine the suitability of the EAF slag as construction material after stabilization. Some of the stabilizers effective for preventing disintegration of AOD slag were examined in laboratory tests for stabilization of the EAF slag. The EAF slag samples were mixed together with stabilizers for melting at 1600ºC and then cooling in a crucible system. With a laboratory granulation system, the liquid EAF slag was cooled rapidly using air. Samples from the tests were characterized by different techniques, including XRD and SEM. Some of the results from the work may be useful for preventing slag disintegration and, thus, enhancing utilization of the EAF slag as construction material, thereby saving valuable natural resources.IntroductionAt steel plants of some MiMeR member companies, steel grades with low carbon contents were produced in Electric Arc Furnaces (EAF). EAF slag was tapped out of the furnace to slag pots for transport to slag yards, where the slag was poured on the ground. Very often, the EAF slag disintegrated during cooling on the ground. Fines from the slag disintegration were often difficult to handle and use as material for road construction [1, 2]. The EAF slag disintegration was rather similar to the disintegration occurring in the slag tapped from some AOD (Argon Oxygen Decarburization) converter heats.Literature studies show that formation of dicalcium silicate (C2S) is the main reason for the disintegration or dusting of AOD slag from production of stainless steel [1-4]. The C2S can form while the content ratio of CaO to SiO2 of the slag, CaO/SiO2, exceeds 1.4 [1]. Values of CaO/SiO2 for the AOD slag are often near to 2.0, making the C2S a predominant slag component. The ß phase of C2S, ß-C2S, transforms into its low temperature ? form in the temperature range of 400-500°C, inducing a volume expansion of nearly 12% [1-4]. The volume expansion disintegrates the AOD slag."

Jan 1, 2008

By Anestis Vlyssides, Elli Maria Barampouti, Sofia Mai, ?postolos Vlyssides

"A new anaerobic reactor variation, the UASB/CO2-stripper reactor was conceived. It consisted of a conventional UASB reactor that recirculated the biogas produced. The sludge characteristics of this system were examined when treating high strength wastewater. From the data collected, it was obvious that the UASB/CO2-stripper system can satisfactorily operate at higher loading rates (25 g COD·L-1·d-1). A pronounced effect on the quality of the granular sludge was observed. The VSS/TSS ratio decreased sharply. A considerable decrease in the mean granule diameter was observed, while the specific gravity of the granules increased. The sludge bed porosity increased significantly leading to a considerable expansion of the sludge bed. These changes in the sludge properties led to a gradual shift of the system towards a fluidized bed process as far as its hydraulic characteristics were concerned.IntroductionIn recent years energy considerations and environmental concerns have increased the interest in direct anaerobic treatment of industrial wastes. The anaerobic method of waste treatment offers, under the present circumstances, a number of significant advantages with trivial or more serious drawbacks over other treatment methods. The major obstacle to the application of the process for this specific purpose is perhaps the difficulty of extending it to a stable and simple operational form. A number of reactor configurations has been developed leading to high biomass concentrations, e.g. the contact process, the filter reactor, the UASB reactor, and the fluidized bed systems, but the process stability problem still remains [1].A prime objective in the operation of anaerobic waste treatment process is the maintenance of a proper pH range. Thus, a possible solution to the process stability problem could be obtained by increasing alkalinity in the anaerobic systems. Therefore, the main objective of this paper is to present and evaluate the results of a system (UASB/ CO2-stripper) with increased alkalinity concentrations."

Jan 1, 2008

By Elsa Olivetti, Randolph Kirchain, Gabrielle Gaustad

"As scrap usage increases, it is often necessary to “dilute” the melt with primary aluminum to ensure the finished product meets compositional specifications. Secondary raw materials, particularly postconsumer scraps, often include high levels of unwanted or “tramp” elements, such as iron and silicon in the case of aluminum. Recent literature on this issue cites several causes including inherent contamination during processing as well as ineffective segmentation at end-of-life. To address this accumulation problem, “upgrading” solutions have been developed including: dismantling of end-of-life products, spectrographic or magnetic sorting of shredded scrap, and “filtration” technologies that remove tramp elements in the melt. Although it is clear that upgrading strategies enable increased usage of scrap, it is not clear that they would be economic or efficient. This work presents a set of analytical methods, based on chance constrained optimization, to quantify the potential environmental and economic value of several scrap upgrading technologies.IntroductionAluminum recycling has a number of key environmental and economic benefits. Compared to other materials, aluminum production has one of the largest energy differences between primary and secondary production: 175 MJ/kg for primary compared to 10-20 MJ/kg for secondary[1]. With energy and cost savings in mind, many producers now have targets of increasing their usage of secondary materials[2, 3]. However, the accumulation of impurities in these recycled material streams provides a significant compositional barrier to these goals[4].A growing number of studies and literature would suggest that accumulation of unwanted elements is a growing problem, in all recycled material streams. In the case of aluminum, the list of problematic impurities is quite large, including but not limited to: Si[5, 6], Mg, Ni, Zn, Pb, Cr[7], Fe[5-7], Cu[6, 7], V, and Mn[6]. Metals recycling is a metallurgical process and is therefore governed by the laws of thermodynamics. The removal of unwanted elements in the scrap stream is dictated by the energy considerations of the melt process. Compared to many metals, aluminum has a high degree of difficulty in the removal of tramp elements, due to thermodynamic barriers. Therefore, with no simple thermodynamic solution, producers must identify strategies through-out the production process to mitigate this elemental accumulation."

Jan 1, 2008

By Carlos Ortiz

The Huelva Flash Smelting Furnace was commissioned in September 1975. The Smelter and the Acid Plant were expanded in 1995 to their present capacity of 300,000 tpa new copper equivalent and one million tonnes of concentrate per year. During these years of operational experience, most of the initial practices have been reviewed, process control has drastically improved and main process equipment has been modernised. The fourth Flash Furnace campaign lasted 9 years (1995-2004) during which 8 million tonnes of concentrate were smelted. Increasing sulphur content in concentrates and new environmental requirements imply new challenges for smelters to keep production and operation costs down. This paper is an overview of the modifications and improvements carried out in the 2007 general shutdown in Smelter and Acid Plants. Al

Jan 1, 2008

By Duck Jae Lee, Kwan Ho Kim, Ji Whan Ahn

"In Korea, reutilization of constructions waste is gaining an increasing attention as generation of construction waste is projected to increase continuously. In current practices, the concrete waste is simply crushed and used as a low application such as paving, back filling, etc. In this study, a new process was developed comprising of heat pretreatment, autogenous milling, and density separation for complete reutilization of concrete waste. Firstly, the concrete waste was crushed using autogenous milling. The coarse size fractions from autogenous milling have a density of 2.5g/cm3 and a water absorption ration 3.0%, which meet the specification of the first class of KS F 2573. The fine size fractions were further separated using a hindered-settling column into two products 1) underflow, 2) overflow. The underflow sample was a high quality fine recycled aggregate which can be used for concrete making, and the overflow sample was an enriched cement material can be also used for CO2 sequestration by mineral carbonation. Introduction Kwan Ho Kim1, Ji Whan Ahn2, Duck Jae Lee1, Hee Chan Cho1 Recently, the importance of resource recycling is gaining a greater attention due to the increasing price of natural resource. Recycling is beneficial for not only the management of waste, but also the reducing of consumption of natural resources and huge energy consumption to treat of natural resource. The construction and demolition waste comprises the major industrial waste generated in Korea. It increased to 54 million tons in 2004, and is projected to increase to over 300 million tons in 2020, as many buildings reach the end of their 30 years life. Among total waste, the proportion of concrete waste was about 30% in Korea. Due to its large volume, recycling of concrete waste is the most important aspect of the waste management. In the current practices, the concrete waste is simply crushed and used as a recycled aggregate. The recycled aggregate has a low quality and most of them are down cycled for usage as paving material, back-filling material, concrete bricks, etc. It cannot be reused for replacement of natural aggregates because cement mortar is not separated perfectly from aggregates. These kinds of recycled aggregates tent to be weaker, more porous and have a higher value of water absorption. When these aggregates are used in concrete making, there are problems of higher total water demand, low compressive strength and durability [1-5]. And recycled fine aggregate is not almost recycled due to its low quality. In this study, a new processing circuit is developed to produce not only highquality recycled coarse aggregates but also fine aggregates and cement material from concrete waste."

Jan 1, 2008