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By Shaik Jeelani, Esperidiana A. B. Moura, Vijaya K. Rangari, Roberta A. Lima, Rene R. Oliveira

This work present the preparation and characterization of biodegradable nanocomposites based on aliphatic-aromatic copolyester (PBAT)/polylatic acid (PLA) blend reinforced by TiO2 nanoparticle. The biodegradable polymeric nanocomposites were prepared by melting extrusion process using a twin-screw extruder machine. The influence of the TiO2 nanoparticle addition on mechanical and thermal properties of PBAT/PLA blend was investigated by tensile and impact tests, SEM, DSC and XRD analysis and the correlation between properties was discussed.

Jan 1, 2015

By Jeffrey L. Zelms

Environmental issues and how they are addressed -- or not addressed -- by the lead industry in the 1990s will determine the eventual fate of lead mining in both the U.S. and worldwide. Clearly, governmental regulation throughout the West will become harsher. Equally clearly, the industry has? failed to educate the public regarding lead. Instead of public support for a critical mineral, we face widespread public ignorance and paranoia. If we can demonstrate the public interest benefits of the industry, the 1990s will be a decade of continuing growth -- not dynamic growth, certainly, but growth at least comparable to the world economy. If, however, we fail to demonstrate the industry's public interest benefits, the 1990s could mark the beginning of the end of our business.

Jan 1, 1990

By C. K. Gupta

The paper reports on the experimental work and results obtained in processing a xenotime concentrate. The rare earth resource concentrate has been treated by three different methods namely, hydrothermal leaching, alkali roasting and alkali pugging or baking. The recovery in hydrothermal leaching with caustic soda at 150-160°C has been 89%. En comparison, processes involving alkali roastings with soda ash at 850°C and with caustic soda at 500°C, and alkali pugging or baking with caustic soda at 200°C have given recovery values close to 100%

Jan 1, 1992

By Adegbenjo Adewale Oladapo, Ibitoye Simeon Ademola, Ladiipo Olufemi Akinbiyi, Adegbola Adekunle Amos, Adeboje Taiwo Bode, Raji Fatai Olasunkanmi

The combined effects of the addition of Silicon (Si) as alloying element and low temperature annealing on the tensile properties of 70/30 brass with Nickel (Ni) and Iron (Fe) contaminants is investigated in this paper. Melts of cartridge brass were made to which 0, 0.5, 1, 2, 3 and 4 wt % of Si was added. These were sand cast into rods of 600 mm by 10 mm diameter and were thereafter machined into standard tensile test samples. Some of these samples were annealed in a muffle furnace at temperatures of 250, 300, 350, 400 and 450 oC respectively and the others were used as control. Subsequently, all the heat treated and non heat treated samples were subjected to tensile tests on a Hounsfield Extensometer and the load – extension plots retrieved were analyzed. Microstructural characterizations of the samples were carried out using Accu-Scope Optical Microscope. The results showed that cartridge brasses subjected to alloying and annealing treatments had improved tensile and yield strengths. However, the tensile properties were increased and maintained within acceptable limits at stress relieve annealing temperatures.

Jan 1, 2015

By T. Tamagawa

Vaporization of zinc and mixing of zinc vapor with CO-CO2 mixtures were studied experimentally to prepare Zn(g)-CO-CO2-Ar mixtures with desired composition for investigating the condensation behavior and efficiency of zinc vapor. The vaporization rate of zinc was generally constant under given conditions, and could be increased by raising the flow rate of the carrier gas, temperature and vaporization area. The Zn(g)-CO-CO,,-Ar mixtures were quenched by a water-cooling sampling tube for measuring the actual composition of the mixtures in the reactor. The oxidation extent of the zinc vapor in the CO-CO2 mixtures had relation to the CO2/CO ratios and the temperatures. Under current conditions, it was necessary to employ the CO2/CO ratio below 0.125 for mixing the zinc vapor with CO-CO2 mixtures without oxidation. In addition, the appearances and zinc contents of the condensed zinc on the sampling tube were also examined.

Jan 1, 2001

By Florian Kongoli

While calcium ferrite slags have been successfully used in continuous copper converting for the last 30 years, ferrous calcium silicate slag was proposed about 8 years ago as an additional alternative for copper smelting. Although both slags are normal extensions of each other their phase relations have not been completely clarified. In this paper the liquidus relations of both slags have been quantified at various areas that cover both of them. The existing experimental data have been first reviewed and discussed in relation to the solidification procedure. An original physical model is then used to predict various diagrams of the liquidus surface of both slags. It is shown that the ternary liquidus diagrams normally used for FeOx-SiO2-CaO system are not suitable for industrial slags. The new model diagrams of Fe/CaO versus SiO2 and Fe/SiO2 versus CaO as well as Fe/CaO versus Temperature and Fe/SiO2 versus temperature are proven to be much more convenient for ferrite and ferrous calcium silicate slags. Based on these diagrams the effect of SiO2 and CaO on the melting temperature is quantified. The effect of Cu2O is also quantified through the model. Some Fe/CaO versus Cu2O and Fe/SiO2versus CaO at various copper contents are predicted and the results show good agreement with the experimental data. It is also shown that in the presence of liquid copper, Cu2O is dissolved in the slag depending on the oxidation degree of the system and might lower the liquidus temperature. Some discussions are also presented taking into account plant observations and important conclusions are drawn for copper smelting and converting

Jan 1, 2006

By Cui Wang, Kexin Jiao, Qiuye Cai, Jianliang Zhang

Prolonging the campaign life of the blast furnace has been an important task for iron makers, and it has been studied for decades. Adding titanium-bearing materials is a generally agreed and effective technique to protect the blast furnace hearth. Titanium from titania additions in the burden or tuyere injection react with carbon and nitrogen and form scaffolds on the hearth surface to protect the hearth from subsequent erosion. In this article, the progress on blast furnace hearth protection of titania additions in Chinese steel companies and research institutions is investigated, and the difficulties in the operation and production, such as little effect after adding titaniumbearing materials and the property deterioration of liquid iron and slags, are analyzed. The future research for protection in Chinese blast furnace is proposed, and a comprehensive process which combines protection of titanium bearing materials with reasonable thermal balance and slagmaking regimes should be established.

Jan 1, 2015

By Marilda Macagnan, Rosana de Cassia de Souza Schneider, Valeriano Corbellini, Tiago Bjerk, Mariela de Souza Vieira

The great potential of Brazil for the agricultural production makes our country a generator of agro industrial residues. In this context, the solid-state fermentation appears as a technology that shows alternative ways for those residues, adding values to these raw materials, through the production of substances of industrial interest, besides reducing the possible environmental problems. The main objective of this study was to apply the bovine fat residue associated to the garden grass for the fungal lipase production. Initially, 75 microbial cultures were isolated from garden grass samples after incubation of the mixture with bovine fat. From these cultures were selected the filamentous fungi, whose lipase production abilities were evaluated. The isolation and the selection were accomplished by using a differential culture medium containing Tween 80 as inducer substrate of lipase production. The colonies with lipolytic potential were detected by the presence of white precipitation haloes on the agar. With agro industrial residues the best lipase producer fungus was identified as Penicillium sp in 6 days of solid state fermentation. The crude enzyme obtained was tested in transesterification process for the biodiesel production.

Jan 1, 2008

By WenCai Li, Yong Ren, Shuai Niu, Xin Hong

"Temperature measurement is very important in metal smelting process. Many devices are used to realize non-contact temperature measurements. Compared to conventional thermocouple, infrared temperature measurement has it's unique advantages. However, using an infrared temperature measurement at the top of the furnace can not obtain the desired optical signal because of disturbance from slag layer, high-temperature gases and other effects. A real time thermometry system with dual-wavelength radiation was presented to get optical signal emitted from molten metal through bottom-blowing nozzle. Taking into account the advantages and disadvantages of bottom-blowing devices, a MHP (Multiple Hole Plug) bottom-blowing device was used, through which the optical signal was transferred to the infrared thermometer by use of optical fiber. After conversion and analysis in real-time, the result was displayed and recorded in computer. After calibration, it could be a good predictor of temperature trend in a metallurgical process. IntroductionAt the refining stage of steelmaking, in order to achieve predetermined chemical composition and temperature, high-temperature molten steel is refined in a furnace such as converter. Because the refining process involved with chemical components and reaction velocities in the furnace rely on the temperature of steel, it is necessary to know the temperature accurately in real time during the process. And temperature measurement is also helpful for the end-point judgment. The temperature in the refining process changes quickly, for instance, in a converter, 300t molten steel is processed in only about half an hour.At present, traditional way of temperature measurement is using a thermocouple probe mounted on a lifter called a sub-lance. The thermocouple is immersed in molten steel and its temperature is measured during the short period until the thermocouple is fused. Accurate and reliable temperature can be obtained by this method, but in consideration of the discontinuous measurement and the costs, missing the end-point temperature may sometimes occur.According to the above background, a method in which a temperature-sensing element such as a thermocouple is immersed directly in molten steel is not suitable for the continuous temperature measurement because materials having such stability are not available. Therefore, radiation thermometry is promising. There have been some reports on radiation thermometry through an observation nozzle through the bottom or side of a refining furnace [1, 2]."

Jan 1, 2014

By Antonio de Ita, Isaias Hilerio, Miguel Barron

"The influence of an unconventional lance with a central nozzle on the multiphase fluid flow in a steelmaking converter is studied in this work by means of computer simulations. The lance has four peripheral supersonic nozzles and a vertical central nozzle. Besides, the oxygen flow in the central nozzle is considered independent from the main oxygen supply. Transient two-dimensional numerical simulations were carried out considering just molten steel and gaseous oxygen as the existing phases. Numerical results show that bath agitation and droplet generation are enhanced as a result of the central nozzle. However, the performance of this lance strongly depends on the distance of the lance tip to the molten steel surface and the velocity of the oxygen jet.IntroductionCurrently, two thirds of the world crude steel is produced through the steelmaking oxygen converter [1]. Given the unquestionable economic importance of this technology, any improvement or optimization proposal is welcome. In the majority of current oxygen converters a top oxygen supersonic jet is blown onto the molten steel through a water-cooled lance to eliminate by oxidation some impurities such as carbon and phosphorus. Conventional lances have inclined peripheral nozzles whose number depends on the converter capacity. During the process, a large amount of gases evolves, forming metal droplets and a metal-slag-gas emulsion [2]. The droplets and the resultant emulsion increase the reaction interfacial area, promoting in this way carbon removal and dephosphorization of the molten steel bath [3]. However, during the blowing stage, the emulsion rises towards the lance and converter mouth and frequently forms layers which accumulate in the lance, reducing the life of the lance tip [4, 5]. It is possible that some freezing of the molten metal occurs due to the low oxygen injection temperature, however there are no reports on this. Besides, frequently undesirable operating phenomena such as spitting and slopping may arise as a result of inappropriate blowing practices or bad lance design. In the oxygen steelmaking industry, novel lances design are needed in order to enhance the decaburization rate and the slag formation and, at the same time, preventing operating practices that decrease productivity and move away the shop from safety standards."

Jan 1, 2012

By Robert D. Boiler, Bill Wilkie

"There is a wide choice of different types of woven filter media for hundreds of different filtration applications. Factors such as type of fiber, synthetic polymers used, weave style, fabric finishes and fabrication techniques all play an important part in selecting the best choice for a specific type of filter and process application. The purpose of this paper is to offer some basic knowledge of these factors and how they can impact the performance of a filter, the life of the media and the overall cost of operation through case studies of actual plant filtration applications.IntroductionThe use of woven filter cloth in liquid/solid separation applications is generally well known. Woven filter cloth, by the nature of the weaving process, offers unique consistency and repeatability when compared to some other filter media such as needled felts, papers, sintered structures and knitted cloth. This unique consistency and repeatability is particularly applicable to woven filter cloth produced using monofilament fibers. These fibers are consistent in shape and form the basis for a woven cloth with predictable pore size and throughput characteristics. Woven filter cloth can be used in most wet filtration applications. Typical examples are the separation of chemical and pharmaceutical solids from process liquors, waste stream solids capture, liquid foods clarification, mining separations, and polymer filtration.EnvironmentOne of the first considerations is the environmental demand of the given process. Though it is tempting to look immediately at the particles in a filtration process, it is often better to consider some of the more basic needs of the system. There are numerous materials available, both synthetic and wire cloth. Each has its own unique set of properties."

Jan 1, 2012

By David Rees

Tomago Aluminium, a 400,OO tonnes per annum primary aluminium smelter in Australia, has installed Ozone for biological control of its process water. The system was designed in Australia by Ionics Watertec Engineering, whilst ANCO Australia monitors the water quality and provides technical support for the project. The motivation was initially to reduce operating costs, however investigations indicated that there were substantial environmental benefits to be achieved by the elimination of a part, or all of, the chemicals being used to control the system. Also the existing chemicals appeared to be losing their ability to control biological growth in the system, in particular, the legionella bacteria. Ozone water treatment commenced in January 1998 and after a short transition period has operated without chemical addition since. There appears to be no doubt that the biological control is effective, the clarity and purity of the water has improved and initial testing indicates that the corrosion control rate is acceptable, although some chemical corrosion control may be introduced after further testing around the total circuit to guarantee protection

Jan 1, 1999

By Bob Drew, Alfred Spanring, Kirschen. Marcus

"Increasing material conversion and energy efficiency, and decreasing carbon dioxide emission levels are crucial for sustainable production processes in the aluminum, cooper, and steel industries. RHI supports these targets by providing a diverse range of solutions including high quality refractory linings, optimum lining maintenance, and process improvements. In this paper examples are provided of process improvements and increased energy efficiency in copper refining, potential energy savings during electric arc furnace and ladle operations in the steel industry, and increased energy efficiency by improved heat transfer in anode baking furnaces in the aluminum industry. In all cases, RHI’s expertise in close collaboration with the customer resulted in an improved performance of the reactor lining and the actual high temperature process with a positive impact on the material conversion and energy efficiency and as a result a decrease in specific carbon dioxide emission levels.IntroductionRefractory linings play an important role in heat transfer during high temperature processes in for example the aluminum, copper, and steel production industries. Due to constantly increasing energy prices worldwide and the increasing demands for environmental and climate protection, improving the energy efficiency and decreasing emission levels of these energy intensive production processes is of significant importance. In this paper, the contribution of modern RHI lining technologies to energy saving measures and the corresponding reduction of specific carbon dioxide emission are described. The type of current refractory solutions for energy intense processes are illustrated with four examples: Optimization and increase of material conversion and energy efficiency in copper refining, energy saving potentials in both electric arc furnace and transport ladle operations in the steel industry, and heat transfer improvements during the carbon anode annealing process in the aluminum industry. These examples focus on particular production processes operating with a high proportion of recycled copper, steel, and carbon anodes. Increased energy efficiency directly decreases the specific energy related carbon emission levels whereas improvements to the metallurgical processes aim to increase material conversion efficiency and, therefore, decrease specific process related carbon emission levels. Significant energy savings can be achieved by maximizing the refractory campaign length through a combination of appropriate refractory material selection, grade zoning, correct installation, careful preheating, and effective maintenance strategies. Besides the efforts to improve the performance and energy efficiency of customer high temperature processes, RHI continuously promotes the development of new low emission carbon-containing refractory bricks and unshaped products."

Jan 1, 2008

By Florian Kongoli

While calcium ferrite slags have been successfully used in continuous copper converting for the last 30 years, ferrous calcium silicate slag was proposed about 8 years ago as an additional alternative for copper smelting. Although both slags are normal extensions of each other their phase relations have not been completely clarified. In this paper the liquidus relations of both slags have been quantified at various areas that cover both of them. The existing experimental data have been first reviewed and discussed in relation to the solidification procedure. An original physical model is then used to predict various diagrams of the liquidus surface of both slags. It is shown that the ternary liquidus diagrams normally used for FeOx-SiO2-CaO system are not suitable for industrial slags. The new model diagrams of Fe/CaO versus SiO2 and Fe/SiO2 versus CaO as well as Fe/CaO versus Temperature and Fe/SiO2 versus temperature are proven to be much more convenient for ferrite and ferrous calcium silicate slags. Based on these diagrams the effect of SiO2 and CaO on the melting temperature is quantified. The effect of Cu2O is also quantified through the model. Some Fe/CaO versus Cu2O and Fe/SiO2versus CaO at various copper contents are predicted and the results show good agreement with the experimental data. It is also shown that in the presence of liquid copper, Cu2O is dissolved in the slag depending on the oxidation degree of the system and might lower the liquidus temperature. Some discussions are also presented taking into account plant observations and important conclusions are drawn for copper smelting and converting

Jan 1, 2006

By Osamu Iida

In the Mitsubishi converting furnace (C-furnace), molten matte continuously undergoes intensive conversion into blister, and an excess amount of heat is generated, even after taking into account heat loss from the furnace, off-gas, and latent heat of melt. To absorb excess heat in C-furnace, recycled granulated converting slags (C-slag) were wastefully charged in the C-furnace. In contrast, supplementary coal is necessary to make up a shortage of reaction heat in Smelting furnace (S-furnace). To utilize the excess heat of the C-furnace effectively and accommodate the unbalance of heat utilization between S and C furnaces, three technological innovations had been carried out. ? Spent anode charging facilities in C-furnace was modified, in order to solve some spent anodes hitting and eroding the hearth bricks. ? Cubic pressed copper scrap charging facilities were installed in C-furnace. ? Facilities were newly installed in C-furnace to treat neutralized residue from the wastewater and dust treatment plants, previously treated in the smelting furnace. Above innovations led to the further effective utilization of heat, increase in production, and savings in energy costs.

Jan 1, 1999

By Thomas K. Chow

For the well-being of all living creatures and in response to green-environment policy from governments around the global, it is essential to reduce SO2 emissions from mining / smelters as well as other industrial facilities around the globe. However, often times, these SO2 containing flue gases and smelter flash gases also include oxygen and SO3, which complicate the SO2 removal process and technology. There are many novel technologies recently developed for removing SO2 from such gases. Most of these, however, have not yet commercially demonstrated that they are technically viable and economically feasible. Many of these novel processes also generate undesired byproducts, which themselves then need to be disposed of in a safe and cost effective manner. Fluor has developed the Fluor SOx Cleanup Process with a wide variety of process configurations to customize removal of the undesired flue gas constituents in a cost-effective manner. The process removes practically all SO2 in the form of salable elemental sulfur and also reduces CO emissions. Successful operation of major components of the Fluor SOx removal technologies has been demonstrated in many commercially operating units. Besides their technical viability and economic feasibility, Fluor SOx removal technologies do not generate any undesired byproducts or encounter SO2 associated corrosion issues. Moreover, these technologies produce high-purity, saleable elemental sulfur. This paper discusses the merits of the Fluor SOx removal technologies, their technical and cost advantages, their simplicity in design and operation, and their readiness for implementation.

Jan 1, 2006

By Jenifer S. Heath

Human health risk assessments can be used in mine permitting, and are frequently used to investigate areas of potential contamination and as a basis for remediation decision making. While some states and US Environmental Protection Agency (USEPA) Regions have their own guidance for the conduct of human health risk assessments, USEPA Headquarters guidance and the underlying science are changing and advancing rapidly. Even outside the US, USEPA guidance can affect risk assessment costs and conclusions, which in turn can affect cleanup costs or permitting options. This paper summarizes recent USEPA guidance and scientific evidence related to human health risk assessment for mining sites. This paper is designed for non-risk assessors, and so focuses on the potential applications and implications of the new guidance rather than the mathematical and theoretical details.

Jan 1, 1999

By Burkhard Seeger et al.

The oxidation of copper sulfides can be highly accelerated in the presence of nitrous gases (NOx) as reaction catalysts. Sulfur and sulfate are simultaneously produced in this highly exothermic reaction. This process, carried out in sulfuric acid medium, is performed at an approximately normal pressure and at a temperature of around 110 °C, in a closed container, adding either oxygen or air. The oxidation is automatically controlled through a computer. The process covers the following steps: Catalytic oxidation, filtration and crystallisation of the hot concentrated liquid, electrowinning, mother liquor treatment through jarosite formation, recovery of dissolved copper and zinc and regeneration of industrial water, and non-soluble residue treatment with extraction of sulfur and recovery of silver and gold. No combustibles are needed. No air is contaminated, and no waste water is produced. Solid residues are in a stable, non-toxic and non-corrosive state of equilibrium. Risk of accident is low. Investment costs are small compared to those of the comparable pyrometallurgical process, and production costs are competitive.

Jan 1, 1999

By H. Singh, Anupam Agrawal, H. S. Grewal

"Erosion in industrial appliances causes huge loss of valuable resources especially when solid particles are present in the working medium. A number of erosion models that are available in the literature claimed to predict the erosion response. In this work, five erosion models have been evaluated using computational fluid dynamics (CFD) methodology. Three most commonly used experimental test rigs (solid particle and unsubmerged slurry jet type and pot type) have been simulated and comparisons with the experimental results have been performed. The study helps in understanding the effect of fluid medium and flow pattern on the erosion process. The knowledge acquired shows that phenomenological based erosion models give better results considering the wide range of operating parameters. The in-depth study of the flow field shows the possibility that erosion mechanism, being parameter dependent, could change with location on the same specimen.1.0 IntroductionErosion is a surface degradation phenomenon which causes the removal of material due to impacts either of solid particles and/or bubbles or gas entrained in a fluid medium. Erosion has various categories depending upon the erosion medium such as, solid particles erosion (solid particles entrained in gaseous medium), slurry erosion (solid particles entrained in liquid medium) or cavitation erosion (erosion caused by exploding gas or vapor bubbles). Humphrey [1] has listed 21 different factors that decide the erosion response of the components under a given working condition. The number of factors involved in the erosion process gives us an idea about its complex nature."

Jan 1, 2012

By A. G. Raraz

Reactive metal electrorefining presents a number of problems that pose obstacles to commercial operation. Cerium has been chosen as the surrogate for certain reactive metals because of its thermodynamic and electrochemical characteristics. A comparative review of the properties for cerium and plutonium has been presented to justify the choice of cerium as the surrogate metal for studying electrorefining. This review has addressed the electrochemical, thermodynamic, and kinetic parameters of molten salt electrorefining of cerium metal to provide an insight to this extremely important process. The cell components and configuration, current efficiency of the process, purity of the cathodically deposited metal and the power requirement of the system are evaluated for a molten CaCl2-MgCl2 salt electrolyte using a molten, stirred impure anode. Crucible designs, salt electrolyte, cell temperature and electrode materials are also evaluated. Selection of the salt electrolyte and the cell temperature have been suggested from this study.

Jan 1, 1992