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By L. Cifuentes

Electrodialysis (ED), i.e. a technique based on the effects of electrically charged membranes on ions in solution in an electric field, has been applied to Cu-Fe-As-Sb- H2SO4 electrolytes similar to those used in copper electrorefining and electrowinning operations. The effects of current density, time and species concentration have been studied in a batch ED cell. The technique has shown to be effective in concentrating and separating a range of ions and points to possible new methods of treating copper electrometallurgy effluents.

Jan 1, 1999

By Yongyong Gong, Qijie Zhai, Zhichen Zhang, Qixin Li, Zhishuai Xu

"Microstructure of semisolid slurry of Al-4.5wt.%Cu alloy was investigated with pulse magnetooscillation (PMO) treatment, the results showed that the PMO treatment can refine the crystal structures of Al-4.5wt.%Cu alloy significantly. The discharging frequency of PMO had a great effect on the solidified structure transformation of semisolid slurry of Al-4.5wt. %Cu alloy, and the primary a-Al particles become much finer and rounder with an increase of discharging frequency. However, over a certain discharging frequency, the grains of primary a-Al become coarse.IntroductionOver the last decade, a lot of attentions have been paid on metal rheoforming process [1-4], since it has higher mechanical properties of formed components, strength to weight ratio and age hardenablity. Nevertheless, semi-solid forming is always performed at high solid fractions (40%-60%), so it has the limitation of viscosity, a tends to be difficult to pour semisolid slurry into the hole of the shot sleeve. Therefore, a series of novel semi-solid slurry preparation methods and rheoforming techniques have been invented, such as, semisolid vibration treatment [5], rheocasting [6], pulsed magnetic field process [7], annulus electromagnetic stirring [8], via ultrasonic vibration process [9], equal channel angular extrusion (ECAE) process [l0] and straininduced melt activation (SIMA) process [11].The electromagnetic field is characterized by its effective grain refinement, green, convenient manipulation and without contamination of melt. The mechanisms of dendrite was fragmentation by electromagnetic field have also been largely proposed [12-14]. The broken dendrite arms then undergo a coarsening process to provide the globular structures and obtain much finer and rounder a-Al particles. When compared with other external electromagnetic techniques, Pulse Magneto-Oscillation (PMO) has obtained more fuvors, owing to narrower pulse width and much lower energy consumption. Furthermore, the PMO treatment can reach finer grains with shorter time treatment [16, 17]. This work aims to study the effects of different discharging frequency ofPMO treatment on the microstructure transition of the semisolid slurry of Al-4.5 wt.%Cu alloy."

Jan 1, 2014

By A. V. Tarasov, V. M. Paretsky

"The design is based on the thermal processing of the wastes in· the intensively bubbled melt in the Vanyukov furnace at the relatively high temperatures (1350- 1450 °C), In this case: -the secondary wastes are not formed; - the especially toxic substances at the outlet from the furnace are absent. The technology was tested on a large scale (on semicommersial bases). Technical and economical basis show profitability of recovery complex for processing of hard garbage waste (HGW) using this technology: the period of capital, investments refunding for the, recovery, complex construction with process annual capacity of 240 thousands tons of wastes is 1,5-2,5 years,"

Jan 1, 2000

By Józef Czernecki

Chalcocite-bornite concentrates of KGHM contain, similarly to chalcopyrite concentrates, 20-30 wt.% Cu but several times less iron (2-7 wt.%) and sulphur (9-12 wt.%). Another useful characteristic of KGHM concentrates is the presence of organic carbon (5.5-8.5 wt.%) in them, which serves as fuel in the flash smelting process. The main contaminants of the concentrates are lead (1.3-2.5 wt.%) and arsenic (0.05-0.4 wt.%) which require appropriate technological treatment in order to remove them from the copper pro-duct. Chalcocite-bornite concentrates are processed in KGHM by two different processes: ? a flash smelting process (Glogow 2 Smelter) ? a shaft smelting process (Glogow 1 Smelter, Legnica Smelter) The shaft smelting process used in the Glogow 1 Smelter and in the Legnica Smelter has higher production costs than the flash smelting process of HM Glogow 2. Additionally, the shaft smelting process employs several concurrently running installations (six dryers, seven briquetting lines, six shaft furnaces, nine converters), the operation of which, including maintenance, requires significant financial expenditure. Therefore, the Company is currently considering the substitution of the shaft furnace process in the Glogow 1 Smelter and in the Legnica Smelter by the one stage flash smelting process located in the Glogow Smelter, with output equaling the copper production capacity of both smelters, i.e. 320 000 ? 350 000 t/a. There are two technological options being considered which differ from each other in their man-ner of flash slag cleaning. In the first, the slag cleaning would be the same as in the existing Glogow 2 Smelter, i.e. the slag would be cleaned by pyrometallurgical reduction of the oxide copper and other metal compounds in the electric furnace in order to produce waste slag containing below 0.6 wt.% Cu. However, the other option of the flash slag cleaning would be carried out in two stages. After preliminary slag reduction in the electric furnace to 3-5 wt.% Cu, there would be flotation of the partially reduced slag.

Jan 1, 2006

By Courtney A. Young

All cyanide species are considered toxic and can be found predominantly in industrial effluents generated by metallurgical operations. For example, cyanide's strong affinity for metals makes it favorable as an agent for metal finishing and treatment and as a lixivant for metal leaching, particularly gold. These technologies are environmentally sound but require safeguards to prevent water contamination. Various methods of cyanide remediation by separation and destruction are available, but certain methods are more effective than others depending on the cyanide species being remediated. Photolytic destruction is regarded as the one technique that is independent of the cyanide species involved. The destruction of various cyanide species by several photolytic techniques has been investigated for the past few years. A literature survey suggests heterogeneous photocatalysis with anatase (TiO,) should behave similarly to homogeneous photolysis with hydrogen peroxide (H,O,) since proposed reaction mechanisms for both processes involve hydroxyl radicals. However, experimental evidence on a suite of cyanide species suggests otherwise. A new mechanism for the photocatalytic destruction of cyanides, especially SAD species, is therefore proposed.

Jan 1, 1998

By Zachery Zanetell

Flotation circuit performance has become increasingly more challenging due to the complexity of available ore sources. To optimize value mineral recovery, the mineralogical composition of the ore should be evaluated and understood. Utilizing a variety of mineralogical and analytical tools, flotation processing challenges can be overcome and potential limitations understood. In this paper, several case studies will be discussed in terms of the value that has been provided through the use of mineralogical analysis to optimize flotation performance.

By Jose Antonio Silva Souza, Emanuel Negrao Macedo, Iara Ferreira Santos, Otacilio Dias, Luis C. A. Venancio

"The Bayer process alumina production generates 0.7 to 2.0 ton of bauxite residue (BR) and an average of 1.0 ton of C02 per ton of alumina produced. The direct reaction of exhaust gases to reduce the alkalinity of the BR may allow a triple gain: improve the storage conditions, open a range of new applications for BR and sequester from 16 to 102 kg of C02 per ton of alumina. This paper shows the measurement of C02 captured during a pilot scale reaction of a suspension of BR in water with flue gas, produced from direct oil burning. Three different types of reactors were used: one spray tower and two packed columns. The inlet and exhaust gases were analyzed using electrochemical and non dispersive infrared sensors. The pH of the suspension was monitored during and after the reaction to evaluate the buffer effect.IntroductionAlumina is mainly produced from refining bauxite using the Bayer process. This process consists of extracting the aluminum oxide through its dissolution in caustic soda and the separation of insoluble residues. The remaining bauxite residue (BR) although not particularly toxic, poses risks to the environment due to the large volume and its reactivity. According to the latest technology it is stacked on sealed deposits specially constructed. To date the vast majority of the bauxite residue that has been produced was stored and were not incorporated into any existing production processes to significant amount with exception to some extent of the sintering process residue at Russia and China [l]. On the other hand, a strategic goal was set in 2010 by the Bauxite and Alumina Committee of the International Aluminium Institute (formed by the majority of the industries) to reuse 20% of BR in 2025 [2]. China has established the same objective for 2015[1].This paper is a sequel of two others presented at TMS 2010/2012 [3-4] and describes:• A pilot plant assembled for testing the carbonation process of BR with gaseous effluents similar of the refining process.• The methodology used to measure the amount of C02 captured during the carbonation process.• The results of the carbonation process, the C02 capture and the buffering effect of the pH.This process is studied in order to consume minimal power and use the effluent as efficiently as possible in different reactors from low cost to ultra high performance. The process is designed for minimizing the power consumption and equipment investment."

Jan 1, 2013

Steel Ladle in Bhilai Steel Plant, SAIL, India, passes through VAD & LF-RH route and this exposes refractory lining to a severe operating conditions. Ladles are lined with in-house manufactured MgO-C refractories. Lining life used to be 35 heats, out of which 18-20 heats were through VAD/LF-RH, hence, ladle availability had become a constraint. Laboratory studies were carried-out to optimize granulometry and composition. Granulometry was developed by adopting Andearssen packing model. A suitable plasiticiser was identified to eliminate inconsistency caused due to variation in resin quality and weather condition. It reduced variation in green bulk density from 6 to 1.3%. Abrasion and slag erosion studies were conducted, which shows that with increase of carbon, abrasion resistance decreases and corrosion resistance improves. Based on these studies, graphite in slag zone was increased from 10 to 12.5% and in metal zone it was reduced to 7.5%. Different process parameters of brick making were optimized to make MgO-C bricks of maximum bulk density with reduced coke porosity. Modified bricks have bulk density of 2.99-3.02 g/cc and coke porosity of 9.5-10.5%. Further, shape of the bricks were changed from side arch to mini keys and thickness was increased from 80 to 100 mm. Mini key bricks are pressed from sides, thus eliminating variation in thickness which is critical dimension for dry joints. These modifications improved average lining life of steel ladles to 64 heats, which includes 37-40 secondary heats. Maximum life obtained is 87 heats.

Jan 1, 2006

By Guillermo J. Román

The precipitation of copper and zinc as cements from a copper alloys' spent pickling solution has been studied at laboratory and pilot scale, with the objective of designing an economic process to recover both metals and render a solution to be either recycled to the pickling process or treated in a standard fashion and produce a non-hazardous sludge. The sulfuric acid spent pickling solution already containing copper and zinc was used first to dissolve another solid residue originated in the copper alloys foundry to neutralize part of the acidity. The resulting enriched solution was treated separately with two reductants,; sodium borohydride and iron powder varying pH and excess of reductant under constant agitation. Under the best conditions, precipitation of over 95 percent of zinc and copper was achieved together with the reduction of lead and cadmium contents respectively. A process for the combined residues treatment is proposed.

Jan 1, 1995

By Georgina De Micco

The National Commission of Atomic Energy is investigating a suitable physicochemical process for the conditioning of spent nuclear fuel and treatment of the scrap of research reactors of the Al-UxSiy type. A possible way of processing is through dry chlorination of the cladding with the purpose of selective separation of the aluminium from the remaining elements such as Fe, Ni, Zn, Cu, etc. transforming them into volatile chlorides. Some important advantages of this method are the thermal stability of the chlorides that allow the easy separation of the halides by physical methods and the low volume of radioactive waste generated. The interactions in the following systems were studied in the range of temperature between 150º-500°C: Al-Fe, Al-Ni, Al-Cu, Al-Zn, Cu-Zn and the pure metals. We found that the reactivity was different depending on if the elements were alloyed or separated. The separation factors of the systems under study were determined. Nickel is perfectly separated from aluminium for all temperatures, whereas good conditions for copper separation were achieved below 400ºC. In the case of iron, complete isolation was never attained. However, by decreasing temperature to 150ºC it is possible to obtain aluminium chloride with less iron content. The separation of zinc from the product was also difficult. It was detected that zinc chloride volatilization decreases when other chlorides were present, for example cooper chlorides. In the Cu-Zn alloy, zinc chlorides remained in the condensed product due to interactions with copper. The samples were characterized by scanning- electron microscopy (SEM), X ray diffraction (XRD) and atomic absorption.

Jan 1, 2006

By Fu-Shen Zhang, Mengjun Chen, Jianxin Zhu

"In China, hazardous e-waste—cathode ray tube (CRT) glass is usually left around, and it is likely to contact with water resources directly. To identify the real leaching characteristics and bioavailabilities of heavy metals Pb and Ba contained in CRT glass in the nature environment, experiments were carried out by simulating the nature environment. The results indicated that Pb and Ba contained in CRT glass were stable in most conditions, which only showed obvious leaching toxicities in strong acidic/alkali conditions. EDTA and DTPA extractable Pb and Ba amounts were extremely high, e.g., EDTA extractable Pb of color funnel glass was up to 1960.07 ìg/kg, indicating that the potential bioavailability of waste CRT glass is very high. IntroductionIn recent years, cathode ray tube (CRT) contained monitors or TV sets has been substituted by novel and better electronic and electric equipments such as LCD and PDP, leaving huge amounts of end-of-life CRTs. 50~85% of the total weight of a computer monitor or a TV set is glass'1-21, which was classified to three categories: black & white glass (BW), color panel glass (CP) and color funnel glass (CF), according to their chemical compositions'3' (Méar et ai, 2006). In order to provide shielding from X-rays generated during the picture projection process, lead, barium and strontium oxides were used in the glass. In general, a color CRT contains 1.6-3.2 kg of lead'4'. Concerning the high toxicity of lead, these waste glasses have posed a potential risk to the environment and human health and researches on these glasses have been attracting wide and tense attention currently."

Jan 1, 2011

By Pekka Taskinen, Hannu Johto

"Copper sulfide concentrates often contain impurities such as lead and iron. The phase stabilities of the sulfide impurity systems in metallurgical process conditions are in many cases unsatisfactorily known. Thermodynamic information of a system gives better understanding of its behavior of metal making processes, but also has effects on the economic and environmental factors of the production process. In this study, isothermal equilibrium and quenching experiments of the stable phases of the system Cu2S-FeS-PbS at 700 and 900 °C were carried out and based on the experimental results, Gibbs triangle of equilibrium phases of the system was outlined.IntroductionThe knowledge of stabilities of phases and the thermodynamic properties of many sulfide systems in the temperature range of 500-1200 °C are quite limited. Especially, the knowledge of liquidus surfaces of multicomponent sulfide systems is essential for making many metallurgical processes more environmental friendly and allowing the utilization of complex concentrates. In this work, the aim was to investigate the phase stabilities of the quasiternary system CU2SFeS- PbS using evacuated silica ampoules. Of greatest interest were the properties of the liquidus surface in the system, in order to be able to predict better the formation of a liquid phase in metallurgical processes."

Jan 1, 2012

By S. Malinov, J. J. McKeown, W. Sha, S. McShane

"A model is developed for prediction of fatigue stress life S-N diagrams for Ti-6Al-4V alloy at different conditions, using Artificial Neural Network (ANN). Different factors which have influence on the S-N diagram are involved as input parameters of the NN, namely microstructure, environment, texture, test/work temperature, surface treatment and stress amplitude. As the output the S-N fatigue diagram is simulated and plotted.The model is based on standard multilayer feedforward neural network. The NN is trained with a comprehensive data set collected from the literature, using Levenberg-Marquardt training algorithm in combination with Bayesian regularisation. A very good performance of the trained Neural Network is achieved. Good correspondence between ANN"" prediction and experimental S-N diagrams is observed. Using the model S-N diagrams for different conditions are predicted and analysed. Graphical User Interface is developed for use of the model. We believe that the model will be important for practical applications in solving various problems on fatigue behaviour of the titanium alloy.IntroductionTitanium and its alloys have an increasing range of applications due to their very good combination of mechanical properties, corrosion and erosion resistance. They are currently finding widespread applications in many industries due to their desirable and versatile properties. Most important among the alloys is Ti-6AI-4Y. Jet aircraft manufacturers are the principal 'consumers of Ti-6Al-4V and it is often specified for critical parts, the failure of which could result in the loss of an entire system. A generic class of Ti-6AI-4V has been developed over the past years and it has become the best understood of all the titanium alloys. The advantages of titanium alloys include: (i) low densities, giving very attractive strength to weight ratios allowing lighter and stronger structures; (ii) superior corrosion and erosion resistance in many environments; (iii) high temperature capability. Although the titanium materials are still considered as expensive materials, for many applications the cost of titanium alloys can be justified on the basis of their desirable properties."

Jan 1, 2001

By Frank Field, Elsa Olivetti, Randolph Kirchain, Elisa Alonso, Gabrielle Gaustad

"The primary technological challenge to increased use of secondary raw materials is the presence of undesirable elemental species in scrap streams. Recent literature indicates that this may become exacerbated by accumulation of impurities over time. Devising strategies to mitigate this problem depends upon understanding the mechanisms of accumulation. This paper takes a first step at characterizing the extent of this issue by presenting a simple analytical model of recycling rate for materials experiencing exponential growth. Low potential recycling rates limit accumulation due to dilution. Empirical analysis of several major materials indicates that, even for current recovery rates, theoretical recycling rates can reach above 60%, making accumulation issues a possibility.IntroductionIt is well known that recycling of secondary materials can provide significant environmental and economic benefits. Energy savings, in particular, can be quite large when substituting secondary materials for primary. Nevertheless, over the past decade, the recycling rates within the U.S. of many materials appear to not be increasing as rapidly as one would predict or even at all (Figure 1). While many barriers exist to increasing materials recycling, one that is cited consistently by the literature and producers[1-3] is compositional limitations; that is the mismatch between the characteristics of secondary materials and those desired for the finished goods into which they would be transformed..One particular aspect of compositional limitations that is receiving increasing attention is the potential for progressive deterioration of the quality of secondary raw materials streams. For some materials, for example paper or polymers, this phenomenon is inherent and relatively rapid[4, 5]. As such, it is well documented and plays a significant role in recycling decision-making even for prompt or in-house material recycling. Conceptually, this issue can manifest in other secondary materials as well, albeit through a different mechanism.As materials are mixed, used, and reprocessed during recycling, they come into contact with and often pick up other elements. The presence of these, so-called, tramp elements alters the original known composition, possibly requiring additional measurement and processing and may even preclude economic, productive reuse; ultimately, this unintentional pick up is unwanted. A growing number of studies and literature would suggest that accumulation of unwanted elements is an emerging problem, in most recycled material streams. Table I provides a brief literature review of various recycled material streams and the accumulated elements noted as problematic by various authors"

Jan 1, 2008

By M. A. Aziz

The electrochemical performance of a series of carbon materials produced from coconut shells, which are very cheap and readily available in Bangladesh was investigated for their viability as anode materials in rechargeable lithium-ion batteries. X-ray diffraction technique was used to measure the interlayer spacing (d002) of the produced carbon materials. A number of half-cells were prepared with the produced carbon materials from coconut shell as working electrode and metallic lithium as counter electrode with 1MLiPF6 electrolyte in a mixture of ethylene carbonate and dimethyl carbonate. The discharge-charge profiles were measured for the different half-cells by using Arbin 24-channel Cyler. The value of interlayer spacing of the coconut-based carbon material was found to be 0.397 nm at 900°C, which is most suitable for lithium-ion insertion into the carbon structure without any expansion. The specific discharge capacity of carbon material from coconut shell heat treated to 900°C was found to be 1015.65 mAh/g. The coconut carbon material heat treated to 900°C delivered 335.22 mAh/g reversible capacity, which is comparable to the commercial carbon/graphite presently used in lithium-ion battery systems. The irreversible capacity loss and coulombic efficiency in 25th cycle of half-cell made with coconut carbon material were found to be 0.16% and 99.83% respectively. The carbon material produced from coconut shell can, therefore, be used as a potential anode for rechargeable lithium-ion batteries.

Jan 1, 2006

By Egil Krystad, Merete Tangstad, Kai Tang, Gabriella Trenell

"A new UMG-Si refining concept has been proposed in this paper. Liquid Si and another liquid metal phase (Me) were separated by the molten slag spontaneously based on their different physicochemical properties. Two metal/slag distribution reactions are able to occur in the system simultaneously. Experimental investigation on the B and P distribution equilibria among Si/slag/Me was carried out in the graphite resistance furnace under the inert atmosphere. The B and P doped silicon was in equilibrium with either the SiO2-CaO or SiO2-CaO-l0%CaF2 slags at 1600 and 1650°C, respectively. The pure Fe and Cu metals were used in order to ""capture"" B and P in the slag phases. B and P in samples were determined by the ICP-MS. B and P distribution coefficients for the Si/slag/Me equilibria were compared with the theoretical calculations. The possible kinetic barriers for the Si/slag/Me three-layer equilibria have been analyzed. The metal contaminations in the three-layer equilibria were also examined. The present study provides a new approach for the refining of MG-Si.IntroductionMost of the impurities in the metallurgical silicon (MG-Si) are rather ""dilute'', ranging from few to several thousand ppms. However, the target impurity levels for upgrade metallurgical silicon (UMG-Si) feedstock are often far below the level of ppm. In such extreme case, the conventional refining technologies face the great technical challenges. B removal by slagging has already been implemented industrially. Removal of Pis frequently carried out by the vacuum distillation. The separating treatments for B and P removals lead to increase refining cost, total CO2 emission and longer pay-back time of solar cell module.It is well known that the phosphate capacities of slags in equilibrium with liquid silicon are extremely lower. However, if we introduce another phase that possesses high ""phosphor capacity"" into the Si/slag system, one would expect to continuously remove P from Si through molten slag to the new ""phosphor capturer"". The so-called three-layer refming concept is thus proposed in the present study. Liquid Si and another liquid phase (Me) are separated by the molten slag spontaneously based on their different physicochemical properties. Two metal/slag distribution reactions are able to occur in the system simultaneously."

Jan 1, 2013

By Jhon Cuya

Titanium dioxide is the well-known catalyst for the photodecomposition of water in UV region and its nanoparticles show better performance than its bulk materials. Furthermore, partially sulfurized TiO2 is expected to be chemically stable and have an enhanced photocatalytic activity compared with TiO2. For this purpose, the sulfurization behavior ofTiO2 nanopartic1es was thermogravimetrically (TG) studied by a thermo-balance with a quartz spring using CS2. From the TG curve of TiO2 nanopartic1es, first, the weight decrease appeared down to around 8 wt% and then sulfurization reaction started at around 500°C at a heating rate of 1 C°/min. The weight increase curve showed a maximum of ca 30 wt% at around 750°?C and then gradually decreased to ca 12 wt% at 1000°C. This would be caused by the formation of TiS2 followed by the decomposition ofTiS2 to lower sulfides, such as Tit.0.8S2 and Ti3S4. From the comparison of the sulfurization of TiO2 nanoparticles with that of anatase, rutile and Ti(OH)4, it was found that TiO2 nanoparticles showed a similar behavior to that of Ti(OH)4.

Jan 1, 2003

By Hong N. Vu, Jitka Jandova

"Gypsum and limestone methods were examined in this study to process zinnwaldite wastes originating from dressing Sn-W ores mined in the Czech Republic. These wastes containing 0.20-0.30% Li and 0.10-0.20% Rb were subjected to magnetic separation to obtain a zinnwaldite concentrate with 1.36% Li and 0.94% Rb. It was observed that processing of the zinnwaldite concentrate with gypsum resulted in almost 96% recovery of Li into aqueous liquors, whilst rubidium extraction was only 25%. At the same time, it is possible to extract almost 92% Li and Rb from the identical zinnwaldite concentrate if the concentrate is processed by limestone method. Lithium carbonate, a final product of both methods was recovered from the refined sulphate solution using K2CO3 as a precipitation agent and/or from unrefined hydroxide solution using gaseous CO2. In the continuation of this study, rubidium will be separated from carbonate solutions after Li2CO3 precipitation as RbAl(SO4)2, an intermediate for Rb2CO3 production. IntroductionLithium is used as an alloying constituent in lightweight alloys, as a heat transfer medium in nuclear reactors and as a component in primary and secondary batteries. With the development of a new generation of electric vehicles, the lithium demand will dramatically grow. Lithium chemicals find extensive application in many industrial branches such as metallurgical, glass, ceramic and pharmaceutical industries. Rubidium compounds are predominantly used in psychiatry and medicine, in magneto-optic modulators, solid-state lasers, phosphors and components of electrolytes for fuel cells. The four most important lithium minerals are amblygonite, spodumene, petalite, and lepidolite. Spodumene LiAlSi2O6 (6.0-7.5% Li2O) and petalite LiAlSi4O10 (3.5-4.5% Li2O) belong to aluminosilcate minerals. Lepidolite (Li.Al)3(Al.Si)4O10(F.OH)2 (3.30-7.74% Li2O), lithium mica, is the most important representative of the mica minerals, a subgroup of the aluminosilicates. It frequently contains 3–5% Rb2O and eventually caesium. Zinnwaldite, which has the general formula K(Li.Al.Fe)3(Al.Si)4O10(F.OH)2 (2-5% Li2O), is regarded as a variety of lepidolite with a high iron content. Commercial amblygonite is a complex phosphate (Li.Na)Al(F.OH)PO4 (up to 9.88% Li2O), however, its deposits have not been commercially exploited because of their small size. Natural brines with a high lithium chloride content are important in the industrial production of lithium [l]"

Jan 1, 2008

By F. W. H. Dean

A very sensitive sensor for the detection and measurement of hydrogen in solid steel is described. This technique is non-invasive and uses a collector to sweep the hydrogen emanating from a steel surface and feed to it sensor. This method is particularly sensitive, resolving fluxes to < 2 pI cm?2 S?I, with a linear measurement up to 1000 pI cm&apos;2 S?I, The collector is held on the steel substrate by magnets and it is shown that emanation of hydrogen from the steel is controlled by bulk diffusion of the hydrogen through the steel. The technique is demonstrated to have an excellent response time and reproducibility.

Jan 1, 2001

By T. Xin

A vertical grain boundary intercepting a horizontal free surface forms a groove to reduce the combined surface energy of the system. We study grooving by surface diffusion with anisotropic surface energy. A recently developed delta-function model of facets is used to describe the surface energy with three or four fold symmetry. It is found that the groove grows following a similarity law. The self-similar groove profile is solved numerically by a shooting method. Even with strong anisotropy, the groove profile can be smooth if the exposed surface orientations do not include a facet orientation. The smooth self-similar groove shape is the same as an isotropic groove, but the size is reduced by a factor that depends on the degree of anisotropy. This induces a large error on the value of surface diffusivity if the isotropic model is used for an anisotropic system. In this talk. we will describe how to correct for this error.1 I Xin, T. and H. Wong, "Grain-Boundary Grooving by Surface Diffusion with Strong Surface Energy Anisotropy," Acta Materialia 51, 2305-2317 (2003). Keynotes: Grain growth, Surface Diffusion, Surface energy, Anisotropy

Jan 1, 2003