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By G. Haesebroek

In L969 Metallurgie Hoboken-Overpelt started an industrial plant for the separation of iron and zinc from a concentrated CoCL2 solution. Iron and zinc are extracted in column contactors by a solvent containing 12 vol % of tertiary amines in xylene. The extracted metals are stripped from the pregnant organic phase by precipitation with a NaOH solution at pH LL. In this paper an overview is given of the industrial process. In order to overcome some drawbacks of this process (low flash point of the diluent, reagent consumption, batchwise stripping) an alternative solvent extraction process has been examined. In this alternative process, iron and zinc are extracted with an or¬ganic phase containing 50 vol % of TBP in Escaid 110. The pregnant solvent is stripped with water in conventional mixer settlers. Despite the ability of this process to overcome most of the inconveniences due to the use of tertiary amines, it suffers from the poor stability of TBP in concentrated chloride solutions, resulting in unavoidable and inacceptable precipitation phenomena in the stripping section.

Jan 1, 1988

By Shuai Wang, Gang-hua Fu, Lu Yang, Yu-feng Guo, Tao Jiang

The fluorine-bearing iron concentrate is one of the refractory raw materials for pelletization, which is mainly used in Baotou iron and steel company with lots of problems, such as narrow roasting temperature range and low compressive strength of products. According to its specific character, the effects of roasting temperature, time on the compressive strength and microstructure of pellets were researched. The results show that low melting substances formed during the roasting was the dominant reason of those problems. High melting substances were added in the roasting to investigate their effects on the roasting properties of fluorine-bearing iron concentrate pellets. Low melting substances were reduced when chromite was added. The compressive strength of products was 3100N/P when the 2% chromite was added at the roasting temperature of 1150 ºC, which was increased 700 N/P compared with the pellets without chromite, and the roasting temperature range was expanded by 170 ºC.

Jan 1, 2016

By Priscilla Aki Mori de Hanashiro, Viviane Tavares de Moraes, Denise Crocce Romano Espinosa, Hugo Hashimoto

"The LCDs are used in televisions, calculators, mobile phones, computers (laptops and tablets), video games and other electronic devices. The advancements in technology make obsolete these devices, causing excessive disposal of LCDs and therefore decreasing life span of landfills. In this context, the LCDs from LED LCD TVs arise as an additional source of waste electrical and electronic equipment (WEEE). Thus, it is essential to develop LCDs recycling methods, beginning with the LCD characterization followed by displays processing, aiming the materials separation and using some Ore Treatment Techniques, and finally, the recovery of indium using acid leaching. The analysis methods that will be used in this work are: Fourier Transform Infrared (FT-IR) and Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES).IntroductionLiquid Crystal Display (LCD) technology is applied in modem televisions, calculators, mobile phones, computers and a wide range of electronic devices. It has replaced Cathode Ray Tube (CRT) technology as the most advantageous display product, due to lower electrical power consumption, size and weight reduction, and no radiation emission [ 1]. The constant improving of LCD screen technology reflects on its growing contribution to the amount of waste electrical and electronic equipment (WEEE): an estimated 50 million tons of WEEE are produced every year [2]. Once the most common method of its disposal are landfills, the LCD technology therefore became an environment issue [3].LCD structure is composed by components made by different materials. In order to develop a LCD recycling methodology that gives the right destination to these materials, a previous characterization stage is required. This characterization includes a disassembly process and material identification analysis. One of the LCD components is the screen, which is composed by polymeric and glass layers. The liquid crystal glass was the starting material of this study. It contains indium in the form of indium tin oxide (ITO) film. This ITO film is deposited in the glass by a sputtering process and acts as the electrode material [4,5]. It has in its composition 90% ofln203 and 10% ofSn02 [6]."

Jan 1, 2014

By Markku Rytkonen, Shaolong Chen, Ilpo Kylmäkorpi, Hannu Mansikkaviita

Though the Peirce Smith (P-S) converter is a traditional type of furnace, continuous improvement in its mechanical and electrical design is still Kumera's approach. Efforts are made particularly on the following aspects: converter head shape for easy fabrication and structural strengthening, oxidation air swivel joint for low pressure drop and low noise level, wind box for even air distribution to tuyeres, drive unit and its control for reliable and handy operation. These improvements have successfully been applied in recent P-S converter deliveries.

Jan 1, 2009

By Fangqing Yin, Qingyu Deng, Zhengfeng Qu, Mengjun Hu, Meilong Hu

Titanium bearing blast furnace slag, which contains 20%-30% TiO2, is a valuable secondary titanium resource. Based on the thermodynamics calculation effect of the temperature on the reduction of the slag in vacuum were studied at certain vacuum degrees. The results show that magnesium vapor and silicon monoxide vapor can be obtained at the condition of high temperature and low pressure. The purity of TiC increases with temperature increasing. When the temperature arrives at 1623K TiC can be obtained besides the reductant carbon. XRD result of the powder collected from the furnace cover show that magnesium and silicon in the titanium bearing BF slag leave the slag system during carbothermal reduction in vacuum. From the above it can be concluded that TiC can be obtained from the titanium bearing BF slag and silicon and titanium in the slag can be separated by carbothermal reduction in vacuum and acid leaching.

Jan 1, 2016

By Vinicius Alves Gomes, Jean Igor Margem, Thallis Cordeiro, Frederico Muylaert Margem, Roberto Faria Jr., Sergio Neves Monteiro, Marina Rangel Margem

Natural fibers are attracting the interest of engineering sectors owing to specific advantages such as lightweight and lower cost as well as for their inherent condition of being renewable, biodegradable, recyclable and neutral with respect to CO2 emission. In particular, the fiber extracted from the malva plant stem is nowadays recognized as one of the strongest lignocellulosic fibers. However, the thermal properties of the malva fibers have yet not been fully investigated. The present work had as its objective to investigate, by photoacoustic spectroscopy and photothermal techniques the thermal properties of diffusivity, specific heat capacity and conductivity of a pressed malva fibers sample. The results revealed that these fibers showed a superior thermal insulation capacity.

Jan 1, 2015

By Guangliang Wu, Dongchang Huang, Xinbin Liu

Oxidation Kinetics of SPHC was analyzed by TGA, and the curve of oxidation weight gain with different temperature was acquired. It is found that, when the oxidation temperature is between 500 and 600 , all the curves are linear; when the oxidation temperature is above 700 , the curves are close to parabolic. At the temperature of 900 , the oxidation weight gain increases dramatically. The TGA results indicate that the activation energy of SPHC steel is 146.19 kJ/mol at the temperature of 500 900 , and an oxidation kinetic model was set up for variable temperature. Based on the temperature change during rolling process, numerical simulation of oxide scales evolution was carried out for SPHC steel, and the simulation result agreed well with measured ones. It can provide a basis for estimating the scale growth and controlling the temperature on site.

Jan 1, 2016

By David Hughes

The paper covers the utilization of on-line analysis in process control of solvent extraction in nickel leach solvent extraction processes in Finland and Australia and in copper heap-leach and solvent extraction in Chile. The goals of and requirements for controlling the solvent extraction stages of the processes are reviewed. The applications at three plants are compared. The development of the technology used is reviewed and design considerations are discussed. Requirements for on-line control and analyzer performance are compared. A new generation of analyzers and its effect on the set-up process of a project is introduced.

Jan 1, 2003

By P. A. Treasure

The EMEW® cell has been developed to overcome a number of inherent limitations in conventional electrowinning technology, particularly the high cost and restricted process windows characteristic of conventional hardware. The technology has been widely demonstrated to achieve high performance for various metals under chemical conditions well outside the limits required for efficient operation of conventional cells. This process flexibility offers significant opportunities for cost savings. in recovery of zinc from primary and secondary sources. The EMEW® technology is now available on a fully engineered basis, as a versatile commercial alternative to conventional electrowinning hardware. Application of the EMEW® cell for recovery of secondary zinc material offers significant advantages to the recycling industry. For example, a selective caustic leach can be used where there are high levels of iron or other contaminants in the target material. The reagent requirement is minimal as most of the caustic is regenerated in the bell and zinc dust that may be required for electrolyte purification is produced in the cell. A high purity zinc powder or cathode is produced in the cell. In the case of acidic zinc electrolytes, the cell is capable of operating over a much wider range of operating conditions than a conventional cell.

Jan 1, 2000

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 J. D. Sloop

This paper discusses the current state of EAF dust recycling at AmeriSteel's Dust Processing Division in Jackson, Tennessee. Included are a brief history of the plant, a description of the facility, a description of the process, and operating data.

Jan 1, 2000

By Ailton S. Ferreira, Rubén J. Sanchez Rodriguez, Sergio N. Monteiro, Felipe Perissé D. Lopes, Teresa E. Castillo

"Polyester composites reinforced with natural lignocellulosic fibers have, in recent times, been gaining attention in engineering areas as lighter and cheaper alternatives for traditional composites such as the ""fiberglass"". One of the strongest, the curaua fiber, is today being considered as reinforcement of composites for automobile interior parts. In fact, several research works are currently being dedicated to curaua fiber composites since physical and mechanical properties are required for practical uses. In this work, the thermal behavior of polyester composites reinforced with up to 30 % in volume of curaua fibers was investigated by differential scanning calorimetry, DSC. The results showed endothermic and exothermic events associated with water release and possible molecular chain amorphous transformation. Comparison with similar composites permitted to propose mechanism that explains this DSC thermal behavior.IntroductionThe modem composite materials, especially those reinforced with synthetic fibers such as glass and carbon, have been used since last century to attend the demands required by most technological fields, from home appliances to aerospace [1]. In fact, fiber composites offer significant advantages over monolitic materials, such as common metallic alloys, plastic and ceramics. One of the most important is the ratio between the ultimate stress and the density, known as the specific strength. For example, in common glass fiber polymer composites, the so called ""fiberglass'', the specific strength of around 400 MPa.cm3/g is higher than any conventional monolitic material. However, drawbacks exist. The energy required to fabricate ""fiberglass"" generates large emissions of C02, which are responsible for global warming. Moreover, ""fiberglass"" is not recyclable and cannot be incinerated [2]. As a result, most synthetic fiber composites end up in landfills or contribute to rivers and oceans pollution."

Jan 1, 2011

By Norman Schapiro

Future ore bodies will, most likely, be more costly to find, mine and process than those now in production because most of them will be of lower grade or found deeper. To evaluate an ore deposit for extraction of metal values it is important to select the optimum economic process from among the many available options. The physical and chemical behavior of the minerals present should govern the process selection. Process mineralogy which combines mineralogy and petrography with process development engineering generates the data on mineralogy, composition and texture of gangue and valuable minerals from which the optimum process steps can be selected in the commercial design of the ore processing plant. These insights also help in solving operating problems caused by changes in the ore body

Jan 1, 1981

By Darryl Lovato, Ramiro Pereyra, Daniel S. Schwartz

"During an annual inventory of nuclear material, a plated steel container which contained plutonium oxide failed. The container had been packaged for temporary storage but had been overlooked and remained in storage for more than 23 years. Although it was determined that the failure occurred through the slip-top rim, a metallurgical evaluation was requested to help to determine the integrity of the container.Optical metallography and scanning electron microscopy were used to analyze the character and degree of corrosion in the container. The depth of corrosion, measured at approximately 10 µm, did not pose a threat to the integrity of the container. However, the corrosion morphology and chemistry did suggest that a galvanic cell had developed between the tin and steel from the condensation of water. The morphology also suggests that the attack of the steel took place over a series of cycles due to changes of the environment.IntroductionMetallographic analysis was requested as part of the investigation into the mechanism of the failure of a slip-top container (#38621) containing plutonium oxide (PuO2) powder. The container had leaked during a special nuclear material (SNM) annual inventory causing contamination and closure of the vault. A photograph of the container and interior container is shown on the right in Figure 1. An initial investigation established that the source of contamination was the consequence of the failure of multiple layers of containment. Initially by the deterioration of the interior plastic bottle and polyvinyl chloride (PVC) bagout bag, and finally through the lid and steel container interface at a location where tape had not adhered properly [1]. Although the source of the breach was established, it was determined that metallographic analysis was important to establish the extent of deterioration of the steel container."

Jan 1, 2008

By Leonardo Mota, Felipe Perissé Duarte Lopes, Marcelo Gomes da Silva, Sergio Neves Monteiro, Helion Vargas

"Natural fibers, as a class of material, are attracting the interest of engineering sectors owing to specific advantages such as comparatively reduced cost and lower density as well as environmental benefits associated with renewability and biodegradability. For industrial applications, thermal properties, among others, are required. These are major requirements, especially in the case of an insulating natural fiber. In the present work, thermal properties of the curaua were investigated by photothermal techniques, i.e., the open photoacoustic cell and a method based upon the monitoring of the temperature evolution as a function of time. This investigation, in tum, permitted to evaluate two important thermal properties: the thermal diffusivity and the specific heat capacity of the curaua fibers. Indirectly, by means of simple mathematical relations, the thermal conductivity was also obtained. The results were compared with other materials and characterize the curaua fiber as an efficient insulator.IntroductionMaterials are gaining attention in recent years owing to their benefits for the environment as compared to synthetics. Being biodegradable, yearly renewable and recyclable, the natural planted-based are considered fully sustainable [1]. In particular, their life-cycle, from growing to industrial processing, absorbs as much C02 as it is emitted and makes them neutral with respect to greenhouse gases responsible for global warming [2]. Typical examples of these environmentfriendly materials are the lignocellulosic fibers that have been used in simple items such as ropes, baskets, textile, modest roofing, etc, since the beginning of our civilization [3]. In the past few decades, these natural fibers have been extensively investigated [ 4-1 O] as a possible reinforcement phase of polymer composites in substitution for synthetic fibers. In fact, engineering application of lignocellulosic composites are today in the market, especially in the automobile industry [11-13]. Out of the hundreds available natural fibers, only part of them exhibits superior properties to be qualified for composite reinforcement."

Jan 1, 2011

By C. Y. Tang, Z. H. Chen, T. C. Lee

"In sheet metal forming process, the forming limit and strain distribution are governed by plastic instability and fracture following strain localization. It has been proved that the temperature gradient caused by plastic deformation as well as friction is one of the crucial factors to induce the strain localization in high-speed metal forming processes. In this paper, a numerical simulation of the sheet metal extrusion process has been conducted by using thermal-mechanical coupling finite element method. An improved mixed finite element method has been used to solve the large deformation elasto-plastic problem. In thermal phase, the transient heat transfer finite element method together with the Crank-Nicholson algorithm has been employed to determine the temperature field. Both the numerical results and the experimental observations reveal that the temperature gradient plays an important role in inducing the strain localization, which eventually leads to fracture failure in the sheet metal extrusion process.IntroductionSheet metal extrusion is such a process where the extrusion punch penetrates into one surface of the sheet metal material to let it extrude and flow towards the outlet of the die. This process can be used to produce protruding parts on a strip material. In engineering applications, the quality of the product is affected by many factors such as stress state, loading speed, material properties and lubrication condition. The research on failure mechanisms and improvement of formability in sheet metal forming processes by exploitation of differential thermal conditions has been of great interest recently [1-3]. It has been proved that the temperature gradient caused by plastic deformation, heat transfer, and friction between sheet and tools is one of crucial factors to affect 'the formability in high speed sheet metal forming processes [4]. In our previous study of sheet metal extrusion, it has been observed that plastic deformation is highly localized and some specimens are subjected to fracture failure in the form of crack propagation [5]. To understand this failure phenomenon, the effects of temperature gradients must not be ignored."

Jan 1, 2001

By S. A. Davis

In July of 1996, the Kroll process began production again at TIMET's Henderson, NV, manufacturing facility. This, after being shut down for several years due to low market demand for titanium. Faced with limited pond capacity and increasing costs for water and wastewater disposal and storage; process changes were made to recycle water used to wash Kroll titanium sponge back into the sponge leaching process. This idea was revisited from 1992-93, when three consecutive attempts to recycle water for this application were unsuccessful due to early pump failure. Since it was uncertain why previous attempts failed, a complete understanding of the existing system was first sought. This included reviewing piping and flow diagrams; taking field measurements for all the piping, valves, and fittings; analyzing the wastewater composition; and modeling the fluid dynamics and control of the system. The fluid dynamics of the system were modeled by breaking the piping network up into nodes and applying the Bernoulli equation to each segment. The fluid flowrate control valves were modeled for this purpose also and the models were used to help specify the required processing equipment and control ranges and tolerances. Once the project was completed, an operating procedure was prepared for operation, startup, and shutdown of the washer water recycle system.

Jan 1, 1999

By Donghai Li, Cheng Pan, Pan Chen, Xuewei Lv, Mei Liu

"Chromite concentrate after beneficiation can not be directly used in the electric furnace. Therefore sintering is one of the effective way to agglomeration, by which the chromite concentrate can be utilized and the power cost of ferrochrome smelting can be reduced. The properties of raw materials and the sintering process of chromite concentrate were studied in this work. The results showed that chromite concentrate used can hardly granulated alone, while chlorite addition can improve the effect of granulation. Moisture plays an important role in sintering process. The granulation effect is optimal when the amount of water addition is 12%. Strength and abrasion index are the evaluation indexes of sinter quality. It was found that the strength of sinter increased with coke dosage increasing to 12%, and then decreased when it continuously increased. Opposite regularities were found for the abrasion index of the sinter.1 IntroductionChromium is a very important metal element which is mostly used in the production of stainless steel. In the earth, it is always formed compound with iron as ferrochromium spinel (FeO.Cr203), and its mineralogical name is chromite.[1] Currently, the global production of chrome ore is about 20 million tonnage every year , in which fine ore (less than 8 mm) accounted for about 80% [2] Although the price of the fine ore is cheaper than the lump one, too much fines will lead to the poor permeability and causes increased electricity consumption while producing ferrochrome. Therefore, the agglomeration process of chrome ore is one of the effective measures to increase the usage ratio of fine ore."

Jan 1, 2013

By Alexander I. Raitchenko

"Although one takes into account only thermal expansion usually at analysis of convection onset, the essential factors include magnetic and electric fields. If Lorentz-force originating from intercrossed electric and magnetic fields' action is directed downwards its effect strengthens gravitational action, and value of critical Rayleigh number (limit value for convection onset) must decrease; increasing of critical Rayleigh number should be observed in case of Lorentz-force directed upwards. Extent of such an influence is determined by relation of Lorentz-force to hydrostatic head in gravitational field. Competition between electromagnetic force due to nonuniformity of electroconductivity (on account of its temperature dependence) and electromagnetic buoyancy force may have ambiguous effect: both increase or decrease of critical Rayleigh numbers. Proposed conception is applicable to analysis of situations in liquid conductors and conductive gases.IntroductionStatic or dynamic situations in fluid media are determined besides properties of these media by a variety of external influences. However one correlate~ the onset of the convection and its development with influences of the minimum quantity of external causes frequently. Most known and usual factors are the gravitational and temperature fields. The number of processes includes heat generation in media volume, and theoretical analysis in these cases takes into account this interior heating together with boundary temperature conditions. But explanation of many natural and technical events is not complete and cogent within limits of thermo-gravitational terms. The whole complex of acting factors which influence convective processes in techniques and nature is greater in many cases. In particular the action of · electromagnetic nature often has not less importance than gravitation one. Stability or instability of a current layer in the plasma must be determined by non-uniformity of electroconductivity owing to non-uniformity of temperature [1]. The presence of Joule dissipation in the plasma through which the electric current flows stipulates initiation of origin of overheated instability [2]. It is known that electroconductivity of arc in the boundary zone changes sharply with radial distance [3], and this must influence its stability essentially. If the intercrossed electric current and magnetic field begin to act on an electroconductive fluid besides the non-uniform temperature field and the gravity, the conditions for the onset of the convection change radi- . cally: both the temperature field and their solutions have to be changed also. The analysis of equilibrium single-time correlation functions of fluctuations must be employed for situations with enlarged number of factors as this was in case for the Rayleigh-Benard problem where the object is a horizontal layer of liquid. This can be carried out by taking into account the detached forces' correlations [ 4, 5]"

Jan 1, 1999

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

"The fibers extracted from the stem of the ramie plant are among the strongest natural lignocellulosic fibers with a potential to be used as reinforcement of polymer matrix composites. Characterization of the ramie fiber has recently been conducted for its physical and mechanical properties. However, the effect of increasing temperature on the ramie fiber behavior has not yet been fully investigated. Therefore, the objective of this work was to perform a thermal analysis on ramie fibers with different diameters within the naturally found range of practical interest. The analysis was conducted by thermo-gravimetric, TGA and DTG, as well as differential scanning calorimetric, DSC, techniques. It was found that the ramie fibers present thermal stability up to 200°C and then suffer a sharp deterioration between 300 and 500°C, resulting in characteristic peaks.IntroductionSince the middle of last century, polymer composites have substituted many conventional monolithic materials in applications ranging from aerospace to sport [l]. The main advantages of these composites are the low density and flexible properties specially using fiber as reinforcement to suit the mechanical performance requirements [2]. These are usually high strength and stiffness requirements that could be reached with synthetic fibers such as glass, carbon and aramid fibers. In recent years, however, the use of synthetic fibers is being questioned in terms of problems caused to the environment. In fact, as non degradable material, synthetic fibers are associated with long term pollution when discarded. Moreover, the expended energy for fabrication and processing can be related to relatively large amounts of C02 emissions and represents a contribution to global warming [3]. Glass fiber, in addition, is toxic and cannot be incinerated as a waste in thermal power plants [ 4]. Possible substitutes for glass fiber are the natural fibers. Many natural fibers are today being considered as viable alternatives to replace glass fiber as reinforcement of polymer composites. In particular, some natural lignocellulosic fiber extracted from plants present a real potential for this replacement [2-8]. Their comparative advantages are lower density and reduced cost as well as renewability, biodegradability, recyclability and neutrality with respect to C02 emission [3]."

Jan 1, 2011