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By Yuya Nakai, Kuniaki Murase, Kazuhiro Fukami, Atsushi Kitada, Ken Adachi

The resources of vanadium –titanium magnetite in China are very abundant, most of which are used to prepare titanium-rich materials. Titanium pigment, electric welding bar and titanium sponge are made from titanium-rich materials such as synthetic rutile and titanium slag etc. To fully utilize titanium resources, many production methods of titanium-rich materials were proposed. In this article, authors review on methods of preparing titanium-rich materials which are Electric Smelting Process, Reduction-rust Process, Selective Chlorination Process, Acid Leaching Process, and sum the advantages and disadvantages of them. Existing problems and possible tendency of production methods of titanium-rich materials are also discussed.

Mar 1, 2018

By J. A. S. Tenorio, A. B. Botelho Junior, I. A. Anes, D. C. R. Espinosa, M. A. Caralho

Recovery of metals from reserves with low grade and from waste with high presence of contamination is a challenge to be overcome. Metals like nickel, cobalt and copper could be recovery from nickel laterite leach waste by many different processes. Among recovery processes that could be applied are ion exchange, solvent extraction and precipitation. The aim of this work was recover copper from liquor of nickel laterite by precipitation using chemical reduction. Copper concentration in liquor was 146 mg L −1 and reducing agent used was sodium dithionite 1 mol L −1. Influence of stirring speed was studied between 0–200 rpm. Results indicated a selective precipitation of copper on solution with others metals at 240 mV. The analyzes were conducted in SEM, energy-dispersive X-ray spectroscopy and XRD, that indicated presence of copper and sulfur.

Mar 1, 2018

By Haydar Güneş

In this study, a hydrometallurgical process was evaluated for the recovery of Nd from a Nd-Fe-B magnet. Each leaching test was performed at the solid (weight) to liquid (volume) ratio of 1:50 and was mixed at 400 rpm at ambient temperature. The effects of 3 different acids (HCl, HNO3, and H2SO4) on the extraction of Nd were investigated and H2SO4 was found to be more effective than other acid solutions. Under the optimal conditions, pregnant leach solution was produced with H2SO4 for subsequent Nd precipitation testing. Each precipitation test was carried out using 100 mL of feed solution mixed at 600 rpm at 25°C. NaOH and H2C2O4 were used for Nd precipitation. The highest Nd was precipitated as Nd2(C2O4)3, 10H2O with C2H2O4 at 20 min.

By K. Morsi, S. K. Kassegne, K. S. Moon, A. Numula

"Current Activated Tip-based Sintering (CATS) is a new process for the powder-based manufacturing of macro, micro and possibly nano-scale features and shapes. CATS enables the selective sintering of powders by localizing current activation conditions through an electrically conducting small tip (either in the stationary or moving mode). This paper presents preliminary experimental results on the CATS of reactive mixtures of Ni/Al powder to form nickel aluminide intermetallics. Preliminary investigations on the effect of current on the reaction characteristics are discussed.IntroductionSpark Plasma Sintering (SPS) has been the subject of intense research over the past decade [1,2, 3,4,5,6]. The process boasts remarkable advantages which include ultra fast heating rates (hence by-passing low temperature non-densifying sintering mechanisms), considerably lower sintering temperatures and shorter sintering times than achieved in conventional sintering. The process is however limited to the generation of simple geometries on the macro-scale. Recently three of the authors conducted work on a novel process ""Current-activated tip-based sintering (CATS)"" [7], where electric current is passed through a conducting tip that is placed or allowed to travel over a powder bed/compact to locally sinter powders. lD, 2D and 3D micro-scale sintered shapes can be generated with the possibility of 3D rapid prototyping on the macro/micro or nano-scale. Although CA TS of single phase powders has been conducted, the CATS of reactive powders has not yet been investigated.The Ni-Al phase diagram contains five intermetallic compounds, AhNi, AhNh, AlNi, AhNi5 and NhAl. Out of these intermetallics, NiAl and NhAl have received the vast majority of scientific and industrial interest [8]. NhAl can be formed by reaction synthesis, where nickel and aluminum reactant powders are heated to a reaction ignition temperature at which the reactant powders are converted to the intended intermetallic product. The reaction is exothermic which gives rise to considerable compact self heating, thus instantaneously raising the compact temperature by several hundred degrees which facilitates sintering [8]. Applying and electric current locally would not only provide for a rapid local reactive sintering, but would generate a number of intriguing scientific investigations. For example, of interest would be, how would the reaction propagation and microstructural/phase evolution be affected by the temporal and spatial temperature and current distributions."

Jan 1, 2011

By Gisele Azimi, Jason Tam, Adrian Lambert

Many advanced technologies in modern society require the use of rare earth elements (REEs). Since these technologies are dominating the world, the demand for REEs is increasing fast. Finding new sources for them is highly of interest. One secondary source of REEs is phosphogypsum (PG), a by-product of the phosphate fertilizer industry. Microwave treatment is investigated as a method to enhance hydrometallurgical recovery of REEs from phosphogypsum, with results showing a 30% improvement in leaching efficiency.

Mar 1, 2017

By Xiaolong Lin, Yuanbo Zhang, Tiancheng Nie, Guanghui Li, Zhizhong Li, Zhiwei Peng, Tao Jiang

The coal-based direct reduction process has gradually become the focus of research concerning direct reduced iron production due to its advantages, including high reduction rate, stable chemical composition, and good metallurgical properties of products. Based on coal-based reduction theory and briquetting technique, this paper reports the use of microwave energy for intensifying the reduction of carbon-containing briquettes mainly consisting of magnetite concentrate and biochar. The heating behaviors of the raw materials show that under the conditions of microwave power of 1250 W, N flow rate of 4 L min −1 and briquetting pressure of 400 N, the briquettes present the highest heating rate. The average heating rate reaches 35.16 °C min −1. When the briquettes are irradiated by microwaves at 1050 °C for 45 min, the metallization degree of the reduced briquettes reaches 93.58%.

Mar 1, 2017

By Marcos Paulo Kohler Caldas, Jorge Alberto Soares Tenório, Mariana Alves de Carvalho, Denise Crocce Romano Espinosa

The massive application of electrical and electronic equipments increased the production and industry development, which leads to a rising envronmental and economic problem: the increase of e-waste’s generation. The main cause to explain this problem is the combination between the diversification of electric and electronic device’s applications and programmed obsolescence, which promotes a high generation the so-called waste electrical and electronic equipments (WEEE). Printed circuit boards (PCBs) are present in almost all WEEE and their heterogenous composition have a considerable amount of metals, including some preciousones. It is necessary to think about viable alternatives for the destination of WEEE, mostly PCBs’. Recycling is an environmental friendly purpose for PCBs’ destination, combined with economic advantage from the recovery of metals. The choice of correct process to recycling depends on the composition of the PCBs, so the correct characterization is required. This work aims to characterize two different PCBs from obsolete computers: motherboard and memory board, concluding that they have 35.5 and 18.92% of metals, respectively, including precious metals as silver and gold. Also, memory board has 0.122% of these precious metals to the detriment of 0.047% from motherboard. )

Mar 1, 2018

By Lifeng Zhang, Zineb Benouahmane, Yaqiong Li

The wettability behavior of graphite with silicon is a key factor for its application as a crucible in silicon making industry. A previous study was carried out to determine the correlation between the physico-chemical behaviors of different types of graphite and the final contact angle for the graphite/silicon system. In this study, experimental vacuum annealing treatment by varying the exposure time at high temperature of 1000 °C processed by X-ray photoelectron spectroscopy and SEM analyses enabled to found a correlation between the oxygen content in the graphite and the final contact angle for the graphite/silicon system. Finally, the experimental results with and without vacuum annealing treatment have shown that a deep infiltration of silicon inside the graphite occurs in case of high level of oxygen content inside the graphite’s pores.

Mar 1, 2017

By Junji Shibata

Waste solution from the Ni non-electric plating process contains 4.0 kg/m3 Ni, 0.1 kglm3 Fe, 0.0 I kg/m3 Zn, 48 kg/m3 S042-, 98 kg/m3 HP032-and 31 kg/m3 laetic acid as a typical composition. Solvent extraction, cementation, ion exchange resin and precipitation methods are possible to use for the treatment of this kind of solution. In this study, solvent extraction of Ni was investigated using two kinds of extractants to clarify the relation between extraction percent and pH for various extractant mixtures. As Ni ion has an octahedral structure with ligands, the synergistic effect for Ni extraction is considered to take place in solvent extraction using two types of extractants. The investigation of the synergistic effect for Ni extraction was carried out in case of various extractant systems.

Jan 1, 2003

By Kazuyuki Kakegawa

"Sintered body of lead zirconate titanate (PZT) was prepared through the spark plasma sintering (SPS) technique. When the mixture of raw materials was calcined at 800°C and sintered at 900°C for 10 min. with SPS technique, the sintered body had almost theoretical density but was a mixture of lead titanate (PT) and PZT. When a calcining temperature of 1100°C was employed, sintered body had a single PZT phase but a lower density. High dielectric constant was obtained for a sample calcined at 800°C, sintered with SPS tecbriique and fired again in the air at 1100°C.IntroductionSpark plasma sintering (SPS) is a recently developed technique for sintering metals and ceramics1. The scheme of SPS is shown in Fig. 1. Sample is put in a graphite die in a vacuum chamber. It is pressed and pulse voltage is applied. The electric current heats the die. It is said that the pulse causes a spark-plasma between particles in the sample. Because of the spark- plasma, sample can be sintered at temperatures lower than that in the ordinary sintering by several hundred degrees of Celsius. The sintering period is also very short2Low sintering temperature and short sintering period in SPS technique cause low reaction rate. It is both disadvantage and advantage. In some cases, the reaction cannot be completed under the SPS conditions. If a mixture of several compositions having different properties can be sintered without a compositional change by the diffusion during the sintering, combination of properties, and therefore a design of property will be possible3. The low reaction rate of SPS may enable such combination."

Jan 1, 2000

By Ruirui Wei, Yanhui Liu, Fangqing Yin, Meilong Hu

In China, Basic Oxygen Furnace (BOF) slag is traditionally used as an aggregate for civil engineering, for road engineering and fertilizer. In order to make full use of BOF slag, the experiments of BOF slag with high temperature roasting has been carried out and the phase transformation is studied. The BOF slag from Chongqing Iron & Steel is roasted in the electric muffle furnace at three different temperature. The influences of the high temperature roasting on change the phase composition of BOF slag was characterized by XRD. The results revealed that SFCA was produced at the high temperature in air atmosphere and melting temperature of slag was lowered. Therefore, if the BOF slag which treated by roasting was utilized in the sintering process, it is advantageous to improve the sintering strength and the formation of the liquid phase and reduce fuel consumption in the sintering production process.

Jan 1, 2015

By Zhi-gang Que, Sheng-li Wu, Guo-liang Zhang, Bo Su, Chao-gang Hou

NOx released during fuel combustion is one of the major air pollutants, such as acid rain and photochemical smog. At present, still not have an economical and effective method of inhibiting NOx emission for sintering flue gas. Therefore, controlling conditions of fuel combustions to enhance the reduction of NOx is important for decreased the emission. In this study, microsintering furnace has been performed to investigate the effects of NOx emission from char-N during coke breeze combustion. The results show that the emission concentration of NOx decreased with increasing temperature when it is sinter bed temperature higher than 1000℃. The lower emission concentration of NOx was obtained when the concentration of oxygen was decreased. And the maximum concentration of NOx will be reduced with the enhanced of heating rate. If heating preservation time was prolonged, it would promote to NOx reduction with reduction substances resulted in lower NOx emissions in the combustion of coke breezes.

Jan 1, 2015

By Yahui Feng, Zhiwen Wu, Chen Chen, Xin Hong

Large amounts of copper slag containing about 40 wt% iron is generated during the process of producing copper. Recovery of iron from the copper slag is very essential not only for recycling the valuable metals and mineral resources but also for protecting the environment. The purpose of this study was to investigate the possibility of separating fayalite by oxidation-reduction process into Magnetite and silicate phases in intermediate temperature condition. Experimental results show that when the oxidation reaction at 1000℃ for 120min and the oxygen flow is 0.1L/min, most fayalite decompose to hematite, less part of magnetite and silica. And then, the mixture of carbon and oxidation product is pressed into blocks and reduced to magnetite and silica at 900℃ for 90min. A magnetic product containing about 57.9wt% iron was obtained from the magnetic separation under a magnetic field strength of 100 mT.

Jan 1, 2015

By F. Chabchoub

A mathematical model has been developed to study the influence of process variables on the horizontal Ohno continuous casting process. The model simulates the heat transfer and fluid flow in a wide plate ingot of pure tin. A two dimensional numerical analysis based on a control-volume finite difference approach, the Semi-Implicit Method for Pressure-Linked Equations algorithm (SIMPLER), and an Enthalpy Transforming Model was used. The shape and position of the solid-liquid interface were calculated at different casting speeds, ingot thicknesses, and cooling device characteristics, as well as various mould temperatures. Results of the mathematical model were compared with

Jan 1, 1992

By Kerri-Ann Hue, Kerry Hasapidis, Ken Babcock, Patrick O'Hagan

"Metallic nanoparticles exhibit properties that are significantly different from individual atoms or bulk materials. Their applications are diverse and have varying uses in areas such as cancer treatment, biochemical sensors, nanoelectronics, and drug delivery. For each application extensive characterization must be performed in order to probe the unique properties of these nanoparticles. In this study, ultra-high resolution mass sensors consisting of MEMs-fabricated, suspended microchannel resonators (SMRs) were used to determine the size and concentration of metallic nanoparticles. With femtogram (10- 15 g) mass resolution, ultra-high resolution mass sensors can weigh individual particles suspended in fluid, and so measure their mass, density, and size. Particle size analysis with these sensors provides excellent accuracy and resolution compared to mature technologies such as light scattering. This technique also provides quantitative information via the ability count particles.IntroductionThe unique electronic, chemical, and optical properties associated with nanoparticles vary with their size, shape, and composition[ 1-4]. These properties are attributed to increased surface area and nanosized mean free path of electrons to the particle surface. Nanoparticle colloidal solutions have been prepared and are commercially available. In recent years, noble metals such as gold, copper, and silver have been extensively researched[5-7]. In order to tailor the optical, electronic, and electrical properties of nanoparticles, size and shape must be controlled. For many applications a monodisperse colloidal solution is ideal. Methods of size characterization include Transmission Electron Microscopy (TEM), Dynamic Light Scattering (DLS), and Electrophoretic Mobility Measurements to name a few[6, 8]. Although TEM can provide shape and size distributions, sample preparation requires that samples be dried on a metal grid and cannot be analyzed in solution. DLS uses curve fitting algorithms that while useful for determining mean particle diameters are not ideal for polydisperse colloidal solutions. New technologies are therefore needed to accurately determine the particle size distributions of metallic nanoparticles."

Jan 1, 2011

By C. Lupi

Electric arc furnace dust generated during the production of steels is regarded as hazardous waste because of the presence of leachable elements such as Cr, Pb, Cd .... Different processes are available according to the management policy chosen by the steelmaker: disposal. recycle and/or recovery. The feasibility of an hydrometallurgical Zn recovery process on fumes generated during the pyrometallurgical treatment of EAF dust has been investigated. The recovery of metallic iron, chromium and nickel as molten metal provides fumes very rich in zinc oxide ( 63.1% ) and poor in zinc ferrite. This secondary dust is still an hazardous waste and represents the raw material for the recovery of Zn and Pb. The waste material is first leached in 1.5 M sulphuric acid at 30°C to provide a Zn, Fe and Mn rich aqueous solution and a Pb and Ca sulphate rich sludge. The iron is eliminated by precipitation because is harmful to the following electrowinning process. The ftltered and purified leached solution is acidified in order to obtain good electrowinning conditions. A pure cathodic deposit of zinc is then produced in an electrolytic cell at laboratory scale.

Jan 1, 1996

By Kuiting Wang, Jinshan Liu, Ninglei Sun, Aiguo Dong, Yeda Lu

"Eliminating the environmental threat caused by waste effluent containing magnesium sulfate derived from the process of nickel laterite sulfuric acid leaching and subsequent nickel precipitation is always a focus in the metallurgy field. A new flowsheet whose procedures include vaporization, crystallization, two stages precipitation of magnesium, causticizing treatment of filtrate and ammonia recycle was investigated. Both the details of the flowsheet and its application are described in this article. It is confirmed to be an effective and economical method to prevent the pollution by the waste effluent, simultaneity, a series of magnesium products recovered during the process own good economic returns.IntroductionSulfuric acid leaching is the conventional procedure of extraction valuable metals from ores in hydrometallurgy field. During the process of nickel laterite sulfuric acid leaching, several metals, including Ni, Co, Al Mn, Fe, Mg etc., migrate into the leachate in the form of soluble metal sulfate. After subsequent procedure of purification, precipitation of Ni and Co and neutralization, an enormous stream of waste effluent which contains a concentration of approx. 15-40g/L Mg is exhausted. Such solution containing magnesium sulfate is toxic, which causes diarrhea for both human and animals. On the other hand, large amount of sulfate acid was consumed during the process of leaching by the compound of Mg, which increases cost of a hydro nickel plant.In arid areas, the waste effluent mentioned above is treated via evaporate pond owning large acreage, which needs not only the appropriate meteorologic condition, but occupies much land. In coastal areas, it is directly discharged to the sea, which probably deteriorates ecological system of offshore strip. The most widespread method to treat with the waste effluent is neutralization by lime cream, the residues of which containing magnesium hydroxide and gypsum are transported to residues pool. Neutralization is a simple process, but it never recycles the Mg and sulfate anion into new application, meanwhile, the residues are potential threat to the environment."

Jan 1, 2012

By Tingyao Liu, Lihui Han, Qing Liu, Bao Wang, Teng Yang, Yong Sheng

This paper mainly investigates the mass transfer phenomena of rare-earth concentrate from leaching process in Rushton stirred tank reactor with rotate speed of 100-600 rpm. In the research, a certain amount of sphere particles with 50-450 μm in diameter is treated as the mineral particles. Comparison of laboratory experiment data with numerical simulation is performed. The results show that the critical impeller speed for complete dispersion is 300 rpm. And the maximum value of turbulence kinetic energy appeared 15 mm away from paddle, where the mixing time is decreased 55% and 80%, respectively, when mineral particles are injected into stirred tank through one or four filling ports. Moreover, with mixing process going on, the numbers of particles near the paddle region accounts for as much as 58% of the total amount. Meanwhile, following the particle diameter increasing, the particle concentration of the upper part of stirred tank reactor is increased.

Jan 1, 2015

By Leizhang Gao, Zhengfeng Qu, Pingsheng Lai, Chenguang Bai, Meilong Hu

FFC process could be used to prepare titanium foams. The mixed oxides CaO-TiO2 with mole ratio 1:2 were sintered into CaTiO3-TiO2 mixture. CaTiO3-TiO2 was then used as cathode and electrolyzed in molten CaCl2 to prepare porous titanium. The porous titanium with the porosity of about 72.15% was first fabricated. The internal pores are in the presence of circular cavities and the pore size is in the range of 50–100 lm. Compared with the powder metallurgy technique using the space-holder this method promises to be lower cost and less processing. It is potential to fabricate titanium foams using FFC process.

Mar 1, 2018

By Shubin Wang

Copper(II) and nickel(II) are often recovered from ammoniacal alkaline solutions by solvent extraction using hydroxyoxime extractants: both copper(II) and nickel(II) are extracted from ammoniacal alkaline solutions and, from the loaded organic phase, nickel(II) is selectively stripped with a dilute acid followed by copper(II) stripping with an acid of higher concentration. Since a small portion of ammonia is co-extracted with copper and nickel, the extracted ammonia should be scrubbed using a dilute acid before metal stripping. In the present study, a mechanistic model has been developed in order to support design and control of this process. The equilibrium distribution ratios of copper(II), nickel(II), and ammonia at 298 K using LIX® 84-I (active component, 2-hydroxy-5-nonylacetophenone oxime) as the extractant are successfully correlated by considering the relevant equilibria. Based on these results, quantitative prediction of equilibrium distribution ratios in the process has been made possible, and suitable conditions for the efficient separation of copper(II) and nickel(II) are discussed.