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By Bora Derin, Sertac Yazici, M. Seref Sonmez

"In this study, the recycling conditions of waste liquor obtained after the production of tungsten boride powder from calcium tungstate by self-propagating high temperature synthesis (SHS) and the following hydrochloric acid leaching were investigated in detail. Environmentally unfriendly and extremely acidic (pH~ -0.3) liquor consisting of calcium, magnesium, and boron ions was treated with 1 M sodium carbonate solution to precipitate magnesium carbonate and calcium carbonate phases. The obtained amorphous precipitates were heated up to the temperature of 400°C for re-crystallization. As a result, MgO, CaC03 and CaMg(C03)z phases were obtained, while sodium, boron, chlorine ions were remain in the solution. The present study is still in progress.IntroductionSelf-propagating high temperature synthesis (SHS) is one of the techniques used in the production of a variety of advanced ceramics, inter-metallic, organic and inorganic compounds, oxygen free single crystals, and polymers [ 1, 2]. The reaction becomes selfsustaining and propagates in the reactant mixture, after initiation in SHS process. SHS products may contain the mixture of several unwanted compounds and elements. Therefore following acidic leaching process may be needed to purify the target product. In the previous study, calcium tungstate (Ca W04), magnesium (Mg) and boric acid (B20 3) mixture were reacted to produce tungsten boride powder by SHS process according to the Reaction 1. Then, magnesium and calcium containing byproducts (i.e. MgO, Mg3B206 and Ca3B206) found in the SHS product were leached out by using concentrated hydrochloric acid (HCl) solution to obtain pure tungsten boride powder [3].Ca W04 + 0.5B203 + 4.5Mg = WB + 4.5Mg0 + Cao (1)After the leaching, filtrate solution consisting of different amounts of magnesium, calcium, and boron requires additional treatment for the environmentally acceptable disposal.Several works were carried out about magnesium precipitation conditions and kinetics from brines. Rabadzhieva et al. investigated the precipitation of Mg(OH)z from brines by using NaOH as well as caustic soda [ 4]. Turek ve Gnot investigated the precipitation efficiency of Mg(OH)z for the temperature range between 10-40°C, while the reaction was kinetically experimented by Alamdiri et al [5, 6]. Homogeneous precipitation of nesquehonite (MgC03.3H20) by the reaction of MgCli with (NH4)2C03 in supersaturated solutions and factors that influence the precipitation of MgC03.3H20, such as reaction temperature, initial concentration, stirring speed, titration speed, equilibration time, have been studied by Wang et al [7]. The precipitation of Mg(OH)z by calcium hydroxide from aqueous solutions was studied by Baird et al. [8]. Stratful et al. focused on conditions influencing the precipitation of magnesium ammonium phosphate from wastewaters [9]. 1031"

Jan 1, 2011

By R. H. Rubisov

Sulphuric acid pressure leaching of nickeliferous laterites has attracted considerable attention from the nickel industry during the past five years. The process is especially advantageous for limonitic laterites that mostly contain goethite, because iron precipitates releasing acid and thus rendering low acid consumption. It is also applicable to mixtures of limonites and saprolites, although at higher acid consumption due to magnesium. Effective process design requires the solubility of metals that precipitate during the process to be known. In the present work, determination of metal solubilities is based on a simple speciation program that assumes the presence of only one dominant complex for each metal. The thermodynamic data for the precipitation reactions are extracted from high-temperature experiments with monometallic systems published previously. The validity of the approach is then tested against mixed bimetallic systems, and finally applied to calculate the solubility of aluminium, iron and magnesium in laterite leaching effluents "at temperature". In both cases of limonitic feed and limoniticfsaprolitic blends, the prediction closely follows metal solubilities measured experimentally at temperatures from 230 to 270°C and at terminal he acidities ranging from 10 to 75 g/L.

Jan 1, 1999

By K. H. Ho

This paper describes a simplified numerical model which is used to study the skull formation of liquid metal on a rapidly rotating disc in centrifugal atomisation. The skull formation is one of the problems limiting the wide use of centrifugal atomisation. The enlarging skull on the atomising disc reduces the yield of metal powder produced and produces a resistance to the centrifugal force which worsens the quality of the powder. It is costly and often difficult to study the flow behaviour by experiments due to the complex heat transfer and phase transformation during the processing. Computer modelling is therefore a powerful tool for mechanistic understanding of centrifugal atomisation. This paper investigates the flow pattern of the melt on the rotating disc as a function of initial temperature, melt flow rate and disc rotation speed as well as the physical properties of the melt, such as density, surface tension and viscosity using the commercial package Flow-3D. Keywords: Solidification, Rotating disk, Centrifugal Atomization

Jan 1, 2003

By David A. Neudorf

Known resources of nickel laterites considerably exceed nickel sulfide resources and there is a growing consensus that most new nickel production will be sourced from laterites. The development of nickel laterite projects is very capital intensive due to inherently low grades, inability to concentrate ore prior to processing, complex processing technology and typically large infrastructure requirements. This has resulted in most recently proposed projects being "mega-projects," to achieve economics of scale. However, this may result in unacceptable project risk in many cases. Furthermore, many known laterite resources are not large enough to support a mega-project. This paper describes an alternative model for nickel laterite project development that allows, smaller scale and reduces capital exposure. The requirements of this model in terms of process technology, infrastructure and commercial innovation are described. Keywords: Nickel, Laterite, Project, Economics

Jan 1, 2004

By Qian Li, Haiyan Leng, Kuo-Chih Chou, Haoyuan Xiao, Zhigang Yu

Magnesium borohydride and Magnesium alanate were synthesized by mechanochemical metathesis reaction. The thermal decomposition behaviors of Mg(BH4)2-nMg(AlH4)2(n=0.5,1) systems were investigated as potential hydrogen storage materials. The results showed that the systems started to desorb H2 at 120 ℃ and desorbed 3.9 wt. and 4.9 wt.% H2 below 300 ℃ when n equals 0.5 and 1, respectively, while individual Mg(BH4)2 started to desorb H2 at 250 ℃ and desorbed only 0.82 wt.% H2. Because of the exist of the Mg(AlH4)2, the isothermal desorption kinetics of Mg(BH4)2 in the Mg(BH4)2-0.5Mg(AlH4)2 systems was 50% faster than that of pristine Mg(BH4)2. In addition, the re-hydrogenation rates also increased 49.4% and 37.9%.

Jan 1, 2015

By Andrzej Warczok

Intensive smelting of copper concentrate in Teniente Converter (CT) leads to the production of high grade matte and highly oxidized slag. Smelting slag is processed in Teniente vascular slag cleaning furnace. The slag composition and forms of copper affect the slag cleaning process and final copper content. Converting of high grade matte in Pierce-Smith converter faces some difficulties in proper slagging of iron oxides. Overblowing in copper making stage allows for slag liquidation but leads to high content of copper oxide in converter slag. Converter slag recycling into CT results in the increase of the participation of oxidic copper. Separate treatment of converter slag and its impact on the forms of copper in CT slag has been analyzed. Thermodynamic properties of a system and kinetic limitations pointed out the negative effect of converter slag recycling on the forms of copper and copper recovery in slag cleaning stage. Experimental results of slag cleaning tests in a crucible scale as well as microscopic examination of laboratory and industrial slag samples supported the above analysis and permitted to formulate recommendations of separate processing of converter slag. Keywords: copper, losses, slag, recycling

Jan 1, 2001

The direct removal of lead ions from D2EHPA-kerosene using metallic zinc as the reducing agent was evaluated. The electrochemical process, called galvanic stripping, is a potential alternative stripping technique when standard chemical methods are not adequate. Four parameters found to be important in the rate of lead removal were studied in a factorially designed experiment. The variable evaluated included D2EHPA concentration, temperature, zinc surface area and solution agitation. Temperature and surface area were found to be the most significant, while agitation and D2EHPA concentration had less influence on the reaction. An activation energy of 22.5 Kcal/mole was calculated indicating a chemically-controlled process. The reaction was also sensitive to the concentration of oxygen in the system. The zinc required was considerably in excess of stoichiometry, possibly due to the dissolution and redeposition of lead: In general, the results were encouraging and demonstrated that lead impurities could be removed from D2EHPA using cementation type reactions.

Jan 1, 1995

By James Cornwell, John A. Elton

"Thermionic induced reactions and radiation resonance catalysis of aluminum and aluminum oxide materials exposed to microwaves and triboemissions will be described and explained from both a fundamental and practical level. Magnetron operation at distinct operating conditions that generates both plasmon and triboemissive radiation will be explained and the resulting tribochemical and radiation resonance catalytic reactions between aluminum, aluminum oxide, water and graphite will be delineated. The generation of hydrogen from these materials using triboemissive radiation and microwaves will be described, and the application of this methodology for hydrogen based technologies will be discussed.IntroductionProtective Systems Directed Energy RadiationProtective Systems, Inc, has developed a new radiation device called the EMR (Electromagnetic Resonator) that has unique characteristics that separates it from traditional microwave and rf radiation devices. The radiation from the EMR device is generated using a modified electronresonance magnetron with proprietary filters and operating characteristics.Electronic Device Shutoff. When electronic devices such as cell phones, computers, and other IC based electronics are placed within the EMR radiation, these devices become non-functional as long as the EMR beam is active. Upon removal of the EMR radiation the devices either become operational again or become operational after a cold start. The devices are not damaged by the irradiation.Faraday Cage Interaction Effect. When any of the above electronic devices are placed in a Faraday cage and activated within the Faraday cage without EMR radiation, they operate normally. However, these devices will still be rendered inoperative when an EMR beam generated outside the Faraday cage is directed at the electronic."

Jan 1, 2010

By Tetsuya Uda

Our recent achievements of rare earth separation technique[1,2] and new process idea for rare earth magnet recycling[3] are reviewed, (1) Binary chloride mixtures of rare earths were separated by a new selective reduction-vacuum distillation process. According to our experimental results, apparent separation factors were 8.1 for the Pr-Nd chloride mixture and 570 for the Nd-Sm chloride mixture. These values are much higher than conventional solvent extraction methods. (2) A study of recycling process of magnet sludge was carried out. The rare earths in the neodymium magnet sludge were extracted by chlorination with FeCI2, An activated carbon was used as a de-oxidation reagent Metallic iron in the sludge was not chlorinated because the iron monochloride is not stable, The extracted rare earth chlorides were easily separated from Fe-alloy and the excess of FeCh by vacuum distillation, 96 % of neodymium and 94 % of dysprosium in the sludge were extraeted into chloride phase, By the vacuum distillation, a mixture of neodymium and dysprosium trichlorides of 99.2 % purity was recovered, On the other hand, the rare earth chlorides can be converted to the corresponding oxides by a pyrohydrolysis reaction accompanied by a formation of HCl gas, The HCI gas can chlorinate metallic iron to FeCh, Therefore, a new recycling process for rare earth magnet waste can be realized as a chlorine circulation type process. During the process, only carbon and water are consumed and there are no toxic pollutants, Moreover, the obtained rare earth oxide can be directly used as raw material in the conventional oxide electrolysis process,

Jan 1, 2003

By Yongqi Sun, Zuotai Zhang

Our study investigated the influence of P2O5 and B2O3 on the viscosity and crystallization behavior of Ti-bearing blast furnace (Ti-BF) slags for the purpose of Ti extraction. The investigation of the crystallization behaviors were carried out using a single hot thermocouple technique (SHTT) and the viscosity was obtained by rotating cylinder method. For the viscosity, the results showed that P2O5 substantially increased the slag viscosity. P2O5 is a network-forming oxide, which increased the degree of polymerization of slags and accordingly increased the slag viscosity. However, both of slag viscosity and apparent activation energy for viscous flow remarkably decreased with B2O3 addition. As a typical network forming oxide, B2O3 was introduced into the network and existed dominantly as 2-D structure, BO3 triangular, which caused a simpler structure and a decreasing slag viscosity. As for the crystallization behaviors of Ti-BF slags, both P2O5 and B2O3 enhanced the crystallization trend of rod-shape rutile and suppressed the crystallization trend of dendrite CaTiO3. Therefore the added P2O5 and B2O3 caused the primary phase change from CaTiO3 to rutile. Additionally, it was found that the rod-shape rutile showed a 1-D growth, whereas the dendrite CaTiO3 showed a 3-D growth style.

Jan 1, 2015

By K:-I. Rhee

The recovery of tellurium from Te-cement obtained during the processing of copper anode slimes was carried out by a series of hydrometallurgical processes, i.e. leaching Te-cement in NaOH solution, precipitation of impurites with the addition of Na2S followed by direct electrowinning of tellurium in NaOH solution. The optimum conditions for each process were determined and discussed in terms of various parameters associated with each step to maximize the recovery and purity of tellurium. The final purity of tellurium from electrowinning in alkaline solution was found to be more than 99.9 %.

Jan 1, 1997

By Guillermo Rios, Arbizum Cristina, Joa Viflals, Alba Sunyer

"Atlantic Copper is one of the largest copper producers in Europe. Its production facilities are located in Huelva (Spain) and account for the smelting of over one million tpy of concentrates to produce up to 260 ktpy cathodes and 900 ktpy of sulphuric acid. During copper concentrate smelting, the slag coming from the flash furnace and PS converters are treated in an electrical slag cleaning furnace. As a result of the treatment of the off gases from this furnace, approximately 2,000 tpy of a Zn-rich filter cake are produced and are sent to authorized waste managers. This paper describes the characterization of this material and the preliminary results of a new process to recover zinc as a pure zinc hydroxycarbonate while lead is collected as an indium-rich anglesite product. The behavior of impurities (Cd, As, Tl, Sn, Sb, Bi, Cu, Se, Te) in the leaching, solution purification and precipitation steps is also reported.IntroductionThe Atlantic Copper Metallurgical Complex in Huelva (Spain) was commissioned in 1970 with a capacity of 40,000 tpy of copper from concentrate. In 1975, the old blast furnaces were replaced by Outokumpu flash smelting furnace (FSF) technology, and the copper refinery capacity was increased to 108,000 tpy. Between 1994 and 1996, an expansion project was carried out to increase the copper from concentrate and cathodes to 250,000 tpy and 215,000 tpy, respectively. This expansion basically consisted of a new sulphuric acid plant, replacement of the anode furnaces by two 400 t units, redesign of the slag cleaning furnace (SCF), an increase in the electrolytic cells to 1,120 and implementation of ISA permanent cathode technology. Furthermore, a debottlenecking project has led to a capacity of 1,000,000 tpy of fresh concentrate since 1997. Meanwhile between 1995 and 1998, a cathode production rate of 260,000 tpy was reached as a result of a progressive increase in the current density in the refinery."

Jan 1, 2012

The increasing need for robust pyrometallurgical furnace construction is driven by two trends in the copper and other base metals smelting industry: ? the desire for increased production within a single furnace line by greatly increasing smelting intensities, which generates high heat fluxes to the crucible. walls, and ? the operational and economic imperatives of maintaining high percentage on- line times and long campaign lives between rebuilds. A key feature of furnaces capable of producing at high rates, while containing intense processes, is a strong, thermally robust wall cooling system. Equally important design aspects include the furnace steel structure, refractories, a cooling water supply and piping arrangment for safety from leaks and disruptions, and instrumentation/controls for monitoring and rapid mitigation of process excursions. Integration of the cooling elements into these furnace systems is essential for optimum performance of the cooling elements, and indeed the entire furnace. This paper discusses the development of a composite copper / refractory water- cooled design, which has been successfully implemented on several copper smelting and converting furnaces, including Kennecott's flash converting furnace, INCO's MK reactor, and Kidd Creek's converting furnace.

Jan 1, 1999

By Huimin Lu, Min Li, Jinghua Zou

"Zeolitic imidazolate frameworks (ZIFs) are new type of porous materials, form inerratic polyhedral in three-dimensional with large cages and small apertures, and appear structural diversity. Their hole size can be adjusted. These materials have high selective adsorption capacity to carbon dioxide. In this paper, zeolitic imidazolate frameworks were synthesized by solvothermal synthesis method with dimethylformamide (DMF) as solvent and structuredirecting agent, divalent metallic ions as cation, and imidazole as ligand. The crystals were characterized with XRD, SEM for their crystal structures and physical properties, the adsorption of the crystals for carbon dioxide was also tested, and the result suggests that these porous materials have a capacity of 1.35ml/g for storing carbon dioxide at 273 Kelvin under ambient pressure.IntroductionGlobal warming caused by the increase of carbon dioxide in the atmosphere has become one of the main environment problems, contemporary research has focused on ways to slow or stop this trend. CO2 capture has attracted attention due to the potential to trap and sequester large amounts of CO2 from concentrated sources such as power plants [1]. Traditional technologies in capturing CO2 include absorption by aqueous amines [2]. However, utilization of this process is energy intensive and expensive. Carbon dioxide storage materials investigated so far can be divided into two categories: chemical storage adsorbents and physical storage media [3]. The first kind of materials can chemically adsorb carbon dioxide within their structures and need thermal energy to release the adsorbed carbon dioxide. The examples of the chemical adsorbents include aqueous amines, gas-hyperbranched aminosilicas [4]. The physical adsorbents store carbon dioxide by physical adsorption of carbon dioxide at elevated pressure and release the adsorbed carbon dioxide at low pressure. The physical adsorbents that have been investigated for carbon dioxide storage include zeolites, carbonaceous materials and other porous materials. Until recently, a new type of microporous material, known as zeolitic imidazolate frameworks (ZIFs), has been reported as promising adsorbents for carbon dioxide storage [5 ~ 10]."

Jan 1, 2010

By J. C. Agarwal

Slags produced by modern smelting furnaces contain copper values which are unacceptably high for discard. The electric arc furnace is employed commercially to clean copper from flash furnace slags but the addition of highly oxidized converter slags to an electric furnace has created operational problems. Highly oxidized Noranda Reactor slags have not been processed successfully in a pyrometallurgical process. These slags, which contain large concentrations of copper (5 to 10 per cent), are treated in slag concentrators (controlled cooling, crushing and milling, and flotation) which produce a copper concentrate that must be resmelted. Though commercially operable, it will be shown that the slag concentrator has important process and cost disadvantages as compared to a pyrometallurgical process. In this paper an economic comparison is made between a pyrometallurgical process and the slag concentrator. For the analysis, five hypothetical smelting plants are considered. Each plant treats 1200 tons of copper concentrate per day and produces 109,000 tons of copper annually. The plant configurations used in this study are:

Jan 1, 1976

By Robert De Saro, Willis Bateman, Ramesh Jain

A Vertical Floatation Melter (VFM) has been developed (sponsored by DOE) which simultaneously decoats and melts organic laden scrap in a single unit. Scrap aluminum is fed into the top of the VFM where it falls through a cone. Hot gases flow upwards through the cone, imposing a variable drag force on the scrap. Equilibrium is reached in which the scrap weight equals the drag force and the scrap becomes suspended. The gases strip off and vaporize the organics. Next, the scrap reaches a liquid state, taking on a more aerodynamic teardrop shape, allowing it to fall into a holding furnace. Heat transfer coefficients are 10 times higher than that of a conventional furnace, allowing rapid melting at a low gas temperature. Typical energy use is well under 2,324 joules/g (1,000 Btu/lbm) with a metal yield from 92 to 98%. This paper reports on the operation and data of a 453 kg/hr (1,000 pph) pilot-scale VFM.

Jan 1, 2000

By Xi-Shan Li, Qian Li, Yong-bin Yang, Li-na Cui, Tao Jiang, Jie Ge

"With regard to control environment pollution in the roasting pretreatment of sulfur & arsenic-bearing gold concentrate, roasting of double-layered pellet was proposed. In the paper, the characteristics of double-layered pellet roasting were studied. Removal and solidification rates of sulfur and arsenic were investigated as primary factors. The result indicated that the removal and solidification rates of arsenic reached up to 95.91 % and 98.95% while the sulfur was 97.19% and 97.90% respectively on the premise of adopting slaked lime as solidified agent at temperature of 6000, the package proportion of 2.14 and roasting time of 3h. However, pyrite and arsenopyrite were transformed to hematite and magnetite and product of solidification mainly consisted of calcium sulfate, calcium arsenate and calcium sulfite within optimum roasting parameters.IntroductionUtilization of refractory gold resources has been gradually concentrated on with the depletion of the gold resources which are easy to deal with in the world [1]. Sulfur and arsenic-bearing gold ore is a typical refractory gold one, in which ultrafme gold is encapsulated in the structure of metal sulfide minerals [2,3], so it gives poor recovery through direct cyanide leaching. These refractory ores need pretreatment before the process of cyanide leaching to undermine lattice structure of pyrite and arsenopyrite containing gold [4] so that the gold could touch with cyanide solution [5]. Among various methods of pretreatment, conventional roasting method is most effective, but this process generates gases such as S02 and As203 harmful to environment. Therefore solidification roasting was proposed to solve this problem occurring in the conventional roasting at the end of last century."

Jan 1, 2013

By Run Huang, Xuewei Lv, Songli Liu, Chenguang Bai

"Titanium alloy was prepared from titania-bearing blast furnace slag (Ti-BF slag) by aluminothermic process in an induction furnace. The effects of aluminum amount on the titanium silicon yield and titanium recovery ratio were studied. The phase transformation and chemical composition of the prepared alloy were investigated by X-ray diffractometry (XRD) and X-ray fluorescence (XRF) respectively. It was found that the mass fraction of silicon and aluminum increased with increasing the aluminum amount, however, the mass fraction of titanium increased first and then decreased with increasing the aluminum amount. Furthermore, both the titanium alloy yield and titanium recovery ratio increased with the increase of aluminum amount. The main phases of the alloy were TixSiy and AlTi3. The titanium alloy samples prepared in various conditions had a composition (wt.%): 38–50% Ti, 29-34% Si, 4-11 Al%, 1.6-2.2 Mn%.IntroductionPanzhihua and Xichang regions in the southwest of China are rich in vanadium-titanium magnetite containing iron, vanadium, titanium and gangue. According to the characteristics of the resource, iron and vanadium are successfully recovered with a blast furnace process and a converter process. However, most content of titanium are entered in the blast furnace slag with TiO2 22% -26% and metallic Fe 2%–6% called Ti-BF slag. Due to the dispersed distribution of Ti in various fine grained mineral phases with a complex combination between Ca, Al and Si, it is difficult to recover the Ti components[1]. This slag is generated at a current rate of 3.6 million tons per year, which adds to the existing 70 million tons of slag produced so far[2]. The slag has had to be piled as large as the mountains, which not only waste of resources but also cause a pollution of the environment. Therefore, the study of integrated utilizing Ti-BF slag has become very significant."

Jan 1, 2012

By Mariana Barcelos, Frederico Muylaert Margem, Giulio Rodrigues Altoé, Pedro Amoy Netto, André Gomes, Sergio Neves Monteiro

Environmentally correct composites, made from natural fibers, are among the most investigated and applied today. In this paper, we investigate the mechanical behavior of polyester matrix composites reinforced with continuous fique fibers, through bending tensile tests. Specimens containing 0, 10, 20 and 30% in volume of fique fiber were aligned along the entire length of a mold to create plates of these composites, those plates were cut following the ASTM standard to obtained bending tests specimens. The test was conducted in a Instron Machine and the fractured specimens were analyzed by SEM, the results showed the increase in the materials tensile properties with the increase of fiber amount.

Jan 1, 2015

By G. Diáz

The PLACID process applied to the recycling of spent lead-acid batteries is being developed by an European Consortium within the Brite-Euram II programme. The status of the project entitled "Lead Recovery from Lead Oxide Secondaries" is described in this paper. The main laboratory and batch experimental results and the preliminary feasibility study are summarised. The description of the demonstration pilot plant and continuous campaigns programme for 1995 are also included. An interesting global approach is proposed, integrating the Placid process in the existing spent battery recycling pyrometallurgical facilities. This yields important improvements in the overall process. Grids would be easily treated by the conventional pyrometallurgical route, obtaining lead alloys,, while battery pastes, slags and fumes would be fed to the Placid process, obtaining pure electrolytic lead (>99.99 %), ideal for battery paste manufacturing. The implementation of the Placid process into the existing battery recycling pyrometallurgical facilities is analyzed from technical, environmental and economical viewpoints. Greater overall lead recovery, lower operating costs, reduced waste production, environmentally safer residues and much better lead product quality are the key advantages. The authors draw the following final conclusion : Integration of the Placid process with conventional pyrometallurgical treatment is a feasible and very attractive alternative route for spent lead-acid battery recycling.

Jan 1, 1995