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By Batric Pesic

Calcium silicate slag (Di-Cal) and magnesium oxide condensate (MgO) are the by-products of magnesium smelting operations, As these oxides have acid neutralizing and metal precipitating properties, it was decided to examine their reactions with (a) individual heavy metals and (b) with a mixture of metals in solution, The resulting solid reaction products were further tested with respect to the stability of the contained metals, The stability of the solid precipitates were examined as a function of the method of precipitation and as function of the solution pH With respect to the method of precipitation, the performance of Di-Cal and MgO was compared to the performance of lime, an industry standard for heavy metal precipitation, Four different pH solutions (4,0, 5,0, 7,0 and 1 LO) were used to study the effect of pH on the stability of the precipitates. It was found that Di-Cal, in most cases, produced the most stable precipitates and thus, outperformed lime, Metal precipitates prepared by the addition of MgO were the most soluble for each metal studied, except for Se,

Jan 1, 2001

By Ray Y. Lin

This study explores the formation of sodium pyrosulfate in molten sodium sulfate resulting from dissolution of SO3 at temperatures between 1160 and 1250 K. Solubility of SO3 in Na2SO4 melts at temperatures between 1160 and 1250 K under gas mixtures of SO2, O2 and argon was investigated applying a thermogravemetric analysis (TGA) technique. The activity of Na2O in the melt was determined with a high temperature electrochemical cell (ECC). Results showed that the SO3 solubility in molten Na2SO4 increases with decreasing temperatures and increasing SO3 partial pressures. Enthalpy of SO3 dissolution in molten Na2SO4 was calculated to be -119 kJ/mol for infinite dilute solutions. Thermochemistry of Na2SO4-Na2S2O7 melts was analyzed based on information obtained from both TGA and ECC techniques. Detailed examinations of the earlier low temperature measurements in the Na2SO4-Na2S2O7 system along with data from this study reveal that the solution behavior between Na2SO4 and Na2S2O7 can be satisfactorily treated as regular with the interaction parameter, , being 2.7 kJ/mol. The phase diagram and the field of SO3 partial pressure has been generated with the thermodynamic calculation using a regular solution approach.

Jan 1, 2006

By Richard Elliott

Current methods for producing low-carbon manganese alloying materials for the steel industry are energy intensive and costly. To enable wider implementation of high Mn steel alloys, a novel solid-state Mn ore reduction strategy is therefore being investigated. This solid-state process, modelled on existing Direct Reduced Iron technology, employs a methane-containing atmosphere to reduce Mn ore pellets to a metal carbide. These pellets may then be smelted, yielding a Mn-rich master alloy. It is well established that CH4 is a suitable reductant for Mn ore powders; however, the reduction behaviour of industrially relevant Mn ore pellets by CH4 is poorly understood. The present work reports the results of an investigation undertaken to address this knowledge gap. The results of this study highlight the significantly different reduction behaviour exhibited by the Mn ore pellets relative to the ore powder under similar conditions and suggest that the diffusion of CH4 into the pellet interior is the limiting factor in achieving complete reduction.

By Jincheng Hu, Honggang Zhong, Qijie Zhai, Congsen Wu, Cheng Zhang, Jingzheng Ye

"The influence of cooling intensity on the solidification structure and ferrite phase content of a new duplex stainless steel (DSS) was investigated by using a thermal simulation setup for continuous casting. The results showed that the characteristics of the solidification structure were similar to their industrial scale manufactured slabs, including chill zone, colunmar zone and equiaxed zone. And austenite morphologies were mainly primary and secondary Widmanstatten sideplates as well as intragranular Widmanstatten plates. In addition, it revealed that the ferrite content increased with an increasing distance from the chill surface and decreased at colunmar to equiaxed transition (CET) position, then the value remained relatively stable at equiaxed zone. Furthermore, the ferrite content presented the same trend with the cooling intensity ranging from 100 mL/min to 2000 mL/min with the values just varying in a slight range.IntroductionThe duplex stainless steel (DSS) is the kind of steel that ferrite phase and austenite phase occupy about 50% respectively, or the content of the fewer phase has to be more than 30% [l]. The success of modem duplex stainless steels is to a large degree due to their higher strength than austenitic stainless steels, higher toughness than ferritic stainless steels, good weldability and high resistance to stress corrosion cracking as well [2,3]. The cost of stainless steel production continues to soar in recent years due to the increasingly higher price of Cr. In order to decrease the production cost, a new type of duplex stainless steel was developed by Bao steel [4]. This newly developed duplex stainless steel had low Cr content compared with 2205 DSS, and was expected to be applied into automobile industry. However, this type of steel was still in the initial stage of development, and the influence of continuous casting process on its solidification process and structure was still unclear, which needed to be studied further. Several works published in literature presented the effect of continuous casting conditions on duplex stainless steel (DSS) 2205, 2304 [5,6]. It was discussed that the cooling intensity in the chill-side had little efficient influence on the phase transformation. In this paper, the effect of cooling intensity on the solidification structure and ferrite volume fraction of this DSS at a given cooling rate was investigated."

Jan 1, 2014

Two pilot-plant investigations were conducted in which strong-base resins were compared with activated carbon for the extraction of gold cyanide from leached pulp from the Golden Jubilee Mine. The results show that gold can be recovered with carbon, but that the extraction efficiency is poor, probably because high concentrations of humic and fulvic acids are. present m the pulp. .However the extraction of gold cyamde from this material with strong-base resins JS very effo:1ent, and the overall efficiency of extraction is better with resin than with carbon, even when the concentration of resin is one-third that of carbon, and the flowrate of resin is one-third that of carbon. The results of the pilot-plant campaign reported in this paper led to the conversion of the Golden Jubilee plant from carbon-in-pulp to resin-in-pulp in February 1988.

Jan 1, 1989

By Mingming Zhang

This paper describes the aluminum electrowinning in a batch recirculation cell system using 1-hexyl-3-methylimidazolium chloride and aluminum chloride (ionic liquids) as electrolyte at low temperatures. The technique proposed to deposit aluminum from ionic liquid electrolyte was a three-component electrolytic cell system. Ionic liquid electrolyte was circulated between electrolytic cell and electrolyte reservoir by ceramic piston pump. Two different anodes were used in the electrowinning and it was found the extruded carbon anode had better electrochemical stability and reusability. The cell performance variables studied were the current density and current efficiency as a function of aluminum ion concentration, electrolyte flow rate and applied cell voltage during batch recirculation operation. Results indicated that the current density was directly proportional to the applied cell voltage, initial electrolyte concentration and electrolyte flow rate. Under batch recirculation operation at applied voltage of 3.5 V and temperature of 80-90°C, 80-90% current efficiency of cathodic aluminum deposition can be achieved when flow rate is 20mL/min and initial concentration is 10 mol/L.

Jan 1, 2006

By Hongmin Zhu, Suning Liu, Kai Huang

"Recovery of silicon particles from the cutting slurry for the manufacturing of solar grade silicon is very important to recycle this kind of special resource. The challenge is to separate the silicon particles from the mixed abrasive particles which contain SiC. Various methods such as sedimentation, centrifugation, and flotation have been conducted, while in present work, a simple and effective novel method was proposed to study the separation of Si and coexisting SiC particles in the cutting slurry. The new process is based on the size difference between the two kinds of microparticles. And the membranes with the different pore sizes of 1µm, 2µm, 3µm and 5µm were used to test the pass ratio and separation efficiency of the suspension. Results shows that the effective separation of Si and SiC microparticles was obtained under the optimal conditions, and indicating great potential of practical enrichment of Si from the coexisting abrasive particles.IntroductionWith the development of the world economy, energy shortage and environment problem is becoming more and more seriously. Solar energy, which is regarded as one of the most important new energy in the word, has received much attention and interest from the scientists [1, 2]. More than 80% solar cells are manufactured by the high purity polysilicon as the raw material. The main process of producing silicon wafer is by multi-wire slicing. In this slice processing, large amount of slurry is produced. The slurry contains more than 30% wt silicon powder, silicon carbide powder as the abrasive, scraps of metal chips, as well as cutting abrasive suspension polyethylene glycol (PEG). The high-purified silicon powders are worth recycling and reusing as the materials for preparing solar-grade silicon though it is a big challenge [3].Most of the current studies were focusing on the recycling of the silicon carbide and PEG, while work on the recycling of the high-purified silicon is not so been focused since there is lacking of very effective separation and recovery technologies till up now. Nishijima utilized the method of superconducting magnetic to recycle the abrasive [4]. Wang applied a combinational process of chemical treatment, high-gravity centrifugation, high-temperature precipitation technique and directional solidification to enrich the silicon [5]. And other purification methods, such as centrifugation [6], froth flotation technologies [7], electrical filed separation [8] and phase-transfer process [9] have been employed. The disadvantages such as using poisonous media or complex equipments decrease the feasibility and efficiency of the above mentioned techniques."

Jan 1, 2014

By René Bustamante

The subject of this paper is a comparative evaluation of different copper smelting gas cooling techniques, using "productivity and quality" criteria. The first section presents a brief description of the operation of the radiant and the evaporative cooling systems, focusing on the differences between each other, in particular regarding. a) mass and energy balances; b) gas flow, temperature and composition; c) dust concentration and recovery. This section includes a brief discussion of the "client-server chain", i.e. the links between the cooling equipment and the down-and up-stream operations. More in particular, the up-stream server relationship impacts on the operating stability of the furnace, and in turn on furnace down-time and Cu production losses; and the down-stream client relationship affects the operation of the electrostatic precipitators, in terms of workload and cost of handling larger quantities of dust of a given dust size The second section deals with the development of indexes to measure and compare value added through the "utilization, productivity and quality" that can be expected of both cooling methods at the physical and economic levels, and the impact on the overall smelter productivity and the final cost composition of copper. The final section presents the results and includes a discussion of the comparative advantages and disadvantages of both cooling systems.

Jan 1, 1999

By Frank Mucciardi, Hujun Zhao, Pietro Navarra

"A heat pipe is a device having a very high effective thermal conductivity in which two-phase flow and heat transfer takes place. Recent research at McGill University has led to a new type of heat pipe that contains a flow modifier. This improvement has enabled the device to operate at the high heat fluxes encountered in the metallurgical industry.This paper summarizes the progress made to describe the fluid flow in the evaporator section of a McGill heat pipe with the goal of understanding how the flow modifier configuration is linked to the film boiling and dry-out limitations. A separated flow model, an instability analysis, a lift-off model and an energy balance model are used to calculate the theoretical CHF with varying flow modifier configurations and operation conditions. A summary of the current work to relate the flow modifier to the dry-out limitation is also given.Determining how the flow modifier affects both the film boiling and dry-out limitation will give insight into improving the flow modifier design so as to extend the operational range of McGill heat pipes in terms of maximum heat flux and heat load capabilities.IntroductionThe McGill heat pipe is a specialized two-phase heat exchanger developed for several metallurgical applications where temperatures and heat fluxes are typically close to or beyond the maximum safe range of conventional cooling technology.Over the last few years, several breakthroughs have brought this device beyond the proof-of concept stage and a series of industrial trials have been performed with success. These trials include two oxygen injection applications for the ferrous and non-ferrous industry [l], and two light metals permanent-mould casting applications [2,3]. Current projects include a blast furnace copper taphole cooling application [4], a copper smelting application and a thermal analysis probe application."

Jan 1, 2004

By Alysson Tadeu Pereira Almeida

Steels with low concentrations of nitrogen, hydrogen and carbon have been in large demand lately. The RH process is a secondary refining process that can simultaneously attain significant levels of removal of these interstitial elements from liquid steel. In the RH process, the melt circulation rate plays a very important role in determining the productivity of the equipment, since it affects the decarburization rate. In the present work, a physical model of a RH degasser in a 1:5 scale of an industrial reactor has been built and used in the study of the circulation rate and of the kinetics of decarburization. The effects of the gas flow rate and of the configurations of the nozzles used in the injection of the gas have been analyzed. The decarburization reaction of liquid steel was simulated using a reaction involving CO2 and caustic solutions. The concentration of CO2 in the solution was evaluated using pH measurements. The experimental results indicated that the kinetics of decarburization can be described by a first order equation. Based on the results, it was possible to determine the contributions of the decarburization in the upleg snorkel and in the vacuum vessel.

Jan 1, 2006

By Moto Goto

PT Smelting, located in Gresik, East Java, is the first copper smelter and refinery in Indonesia. Since the first charging concentrate in December 1998, many equipment troubles have been systematically eliminated, and the present operation is smooth and has accomplished the design capacity of 200,000 tonnes per year of LME, grade-A copper cathode. This paper describes troubles and countermeasures, which were experienced until now.

Jan 1, 2002

By Varadajan Seshadri

Kambara Reactor (KR) consists of a ladle where pig iron is stirred by an impeller during addition of a flux powder. The objective is to improve agitation leading to dispersion, of the flux powder, in the molten pig iron in order to improve desulfurization of the liquid melt by improving solid liquid interaction. The life of the impeller is limited as it is subjected to abrasion at high temperatures. The shape and design of the impeller also has an effect on the performance of this reactor. A 1:7 scale cold model of a KR unit of the Companhia Siderurgica de Tuberao ,one of the integrated steel plants in Brazil was constructed in order to evaluate the mixing and mass transfer conditions. Mixing efficiency was investigated by tracer additions and subsequent measurement of conductivity. Mass transfer in the reactor was assessed through iodine transfer between water and kerosene and employing a macroscopic model. Mixing depends on impeller shape and depth of immersion The role of dispersion is highlighted by faster kinetics when impeller velocity is increased. The results enable assessment of design aspects of the impeller on the process.

Jan 1, 2006

By O. Morfín

The most probable source of Pb contamination in the perennial reach of Aravaipa Creek, Arizona, has been determined using Pb isotope ratios and total metals analyses of samples collected from the ephemeral and perennial reaches and mine wastes located in the Aravaipa Mining District . Previously, elevated levels of Pb, Cd and As in fish in the perennial reach of Aravaipa Creek, a protected wilderness area,, were assumed to be due to off-site transport from abandoned flotation tailings piles located at Klondyke, Arizona upstream of the wilderness area.Our work replaces this inference with isotopic data that allows us to confirm this hypothesis. The Pb/Zn deposits of the district were mined between the late 1890s and the late1960s, with the most significant ore production coming from one deposit in a rhyolite dike swarm on the Western front of the Santa Teresa Mountains, a granitic pluton of Cretaceous-Tertiary age (~65 ma). Mineralogy has been well constrained across the length of the lode system: Pb and Zn sulfides predominate in the NW sector, and a mixed suite of hypogene/supergene Pb sulfide and Pb oxide minerals comprises the majority of its SE corner. Total metals analyses and comparison of metals ratios serve to constrain the source and transport of certain metals within different parts of the system. Pb isotope ratios in samples, obtained by ICP-MS analysis, define two distinct contributors. The first end-member (208Pb/204Pb = 38.513 to 38.721 and 207Pb/204Pb= 15.550 to 15.598) is characteristic of the mixed, oxide/sulfide ores at the SE end of the deposit. A second end-member (208Pb/204Pb = 38.855 to 38.946 and 207Pb/204Pb = 15.610 to 15.625) characterizes samples taken from the NW, purely Pb sulfide end of the lode. Pb isotope ratios from perennial reach sediments are closely correlated with ratios given by samples from the Klondyke tailings site and by Pb sulfide samples from the NW sector, the primary source of ores processed at Klondyke.

Jan 1, 2003

By Xudong Liu, Feng Chen, Yufeng Guo, Wei Chen, Tao Jiang

Willemite is typically found in oxidized zinc ores and metallurgical secondary resources but without effective extraction method yet. Based on the ideas of zinc phase reconstruction in the willemite, the extraction of zinc from willemite by calcified-roasting using CaO as additive and ammonia-leaching process was studied in this paper. The influences of CaO dosage, roasting temperature, roasting time on the phase transformation and zinc leaching rate were studied, which were characterized by XRD. The results indicated that Zn2SiO4 was transformed into ZnO or Zn2CaSi2O7 .After roasted with 1.4 times of theoretical CaO dosage at l280 for 40 minutes, willemite was thoroughly transformed into ZnO. The zinc leaching rate of the roasted sample was 97.45% in NH4Cl-NH3 H2O leaching system, which increased by 91.40 % compared with zinc leaching rate of 6.05% when willemite was directly leached in NH4Cl-NH3 H2O system.

Jan 1, 2016

By E. Gratz, U. Pal, A. Powell, S. Pati, J. Milshtein

"The solid oxide membrane (SOM) process has been used at 1150 'C to produce magnesium by direct electrolysis of its oxide. Magnesium oxide is dissolved in a molten CaF2-MgF2 ionic flux. An oxygen-ion-conducting yttria-stabilized zirconia (YSZ) SOM membrane separates the cathode and the flux from the anode. During electrolysis, magnesium ions are reduced at the cathode and Mg(g) bubbles out of the flux into a separate condenser. The flux has a small solubility for magnesium which imparts electronic conductivity to the flux. The electronic conductivity decreases current efficiency of the process and also degrades the YSZ membrane. This study investigates different methods for reducing the electronic conductivity of the flux due to magnesium solubility. One effective method shown here is inert gas flushing near the magnesium nucleation site. Potentiodynamic and potentiostatic experiments along with AC impedance spectroscopy are used to characterize the effectiveness of the approach.IntroductionMagnesium is the third most abundant metal in the earth's crust. Since magnesium is the lightest of all metals used for construction alloys, magnesium is the leading candidate to replace steel and aluminum in automobiles. Automobile manufacturers would like to increase magnesium content from 4-5kg per vehicle to 40-IOOkg per vehicle [I]. Using magnesium alloys instead of steel and aluminum can reduce automobile weight and improve fuel efficiency. However, in order for automobile manufactures to make this change, it is generally believed that new cost effective methods of magnesium production must emerge.One approach for magnesium production which has been shown to be effective on a laboratory scale is the direct electrolysis of magnesium oxide utilizing an oxygen-ion-conducting solid oxide membrane (SOM), this is known as the SOM process [2]. A recent study estimated that a commercial SOM plant could produce magnesium from magnesium oxide at a cost that is 40% less than current technologies [3]."

Jan 1, 2012

By Eltefat Ahmadi

Iron-free titanium oxycarbonitride (TiOxCyNz) is a promising feedstock for production of titanium tetrachloride (TiCl4) at low temperatures. In this study, the effects of leaching variables such as temperature, time, particle size of staring material and concentration of the leaching solutions were evaluated on iron removal from nitrided Malaysian ilmenite by Becher process. The nitrided ilmenite was prepared by isothermal reduction with graphite at 1200 °C for 3 h in H2-N2 atmosphere. The aerated leaching experiments were conducted at 50–90 °C with addition of 0.3–2.0 wt% of NH4Cl catalyst. The highest extent of iron removal (XFe) was obtained at about 96.2% for the sample leached at 90 °C for 7 h with 2.0 wt% NH4Cl. The iron concentrate and titanium oxycarbonitride product were characterized by ICP-OES, XRD, XRF and SEM-EDX analyses. The results indicated that the aeration leaching process was a successful route to prepare low-iron titanium oxycarbonitride.

By Alejandro R. Alonso, Lizet Alvarado, Gretchen T. Lapidus

"Cobalt and lithium recovery from spent Li-ion secondary batteries has been increasingly studied in recent years due to the high value of both metals and the low proven reserves for lithium. The standard method employed until now has been the deactivation and crushing of the batteries, followed by leaching of the L1C0O2 spinel from the battery cathode using acid solutions, such as 1.5 to 2.0 M HC1 or H2SO4, in a temperature range from 120°C to 250°C. Once leached, the cobalt is separated by electrodeposition and the lithium by precipitation, using large amounts of carbonate to bring the solution to alkaline pH values. In the present work, citric-thiosulfate solutions are used for the spinel leach at room temperature, favoring a reductive environment at room temperature, which stabilizes the cobalt(II) as cobalt citrate and lithium(I) at pH 5, and recovers approximately 99% of both metals.IntroductionThe Li-ion batteries industry has become an important economic sector in recent years. This type of battery is the most promising system for energy storage, because of its high efficiency in charge-discharge cycles, and its adaptability to many configurations. The demand will probably increase because of the need for mobile energy sources in many types of devices ranging from cell phones, tablets, and laptops to medical, navigation and sophisticated communication equipment and even in automobiles.One major problem related to the use of these batteries is the method employed for recycling the components, mostly cobalt and lithium. Currently, there are two processes employed on an industrial scale: the Sony/Sumimoto process, used since 1990 [1] and the Toxco Process [2]. In the first case, incineration is used to open the batteries and at same time volatilize the organic solvents. After that, the metals (copper, iron and aluminum) are physically separated. The cobalt and lithium are recovered as oxides and then thermally treated in order to recycle them for new batteries manufacture."

Jan 1, 2012

By Norbert Hort, Karl Ulrich Kainer, Carsten Blawert, Daniel Fechner

"With the development of new heat resistant magnesium alloys, the automotive industry has introduced several parts to the drive train. The rising number of large magnesium components will result in a higher quantity of automotive post consumer scrap and the changing legislation will force car manufacturers to take magnesium recycling into consideration. So far post consumer scrap has not been used for magnesium alloy production. Quite a reasonable amount of automotive scrap is likely to end up in a mixed light metal shredder fraction. The separation of mixed magnesium scrap according to several alloys is complex. Therefore secondary magnesium alloys made from blended post consumer scrap would be useful. For this work a matrix of potential recycling alloys was prepared by chill casting and high pressure die casting. The materials were investigated for their microstructure, mechanical properties, heat resistance and corrosion properties. The results will be presented in this paper.IntroductionWithin the last ten to fifteen years several heavy magnesium parts have been assembled in passenger cars, such as gear box housings and crank cases [1, 2]. Reasons are the lately developed new heat resistant alloys and the increasing responsibility of automotive manufacturers to reduce the vehicles weight and thereby CO2 emissions. The latter is pushed by international legislation [3, 4]. The rising quantity of magnesium in automobiles will result in an increasing amount of so called post consumer scrap at the end of the vehicles life.So far magnesium recycling was done only for clean scrap that is free from impurities, contaminations and sorted according to a chemical composition or a single alloy respectively [5- 15]. The latter is also called class 1 scrap and mainly consists of sprues and runners from magnesium die casters [15, 16]. For the upcoming automotive post consumer scrap the materials quality strongly depends on the way end of life vehicles are treated. By proper dismantling of old cars, the bigger magnesium components could be collected and possibly treated similar to class 1 scrap [15]. Up to date automotive manufacturers have no uniform recycling system for end of live vehicles. Most probably a considerable quantity of old cars will be shredded. The resulting light metal shredder fraction will contain aluminium and magnesium scrap, both from several alloys. A separation of mixed magnesium and aluminium scrap is feasible according to [17]. Other authors claimed that the grade of separation of magnesium from aluminium is still not sufficient for a proper industrial recycling process of magnesium post consumer scrap [15, 16]. If an automatic sorting is possible it will probably be very expensive [18]. Therefore, so far the main use of post consumer scrap has been the steel desulphurisation and aluminium production [15]. The use of post consumer scrap for magnesium alloy production has been considered already by [15] and [16] but some problems have to be approached."

Jan 1, 2008

By H. Hirayama, T. Okura, O. Kato

"Saganoseki Smelter & Refinery, one of the largest copper smelters in the world, has the annual capacity of 300,000 metric tons in copper content with two flash furnaces, six Pierce-Smith type converters, two anode furnaces, four acid plants, three tank houses and perfect pollution control system.Coping with the many severe conditions surrounding the copper industry in the last decade, Saganoseki Smelter has kept performing the stable operation, while enhancing the smelting capacity and developing new technologies such as the hydrometallurgical treating of converter dust recovered at electric precipitators. Especially in the operation of flash furnaces, which are of Nippon Mining's conversion type using hot air in a temperature of l,000ºC some technological improvements and complete operation control factors have approved the concentrate feed rate to reach to 2,200 tons a day for a flash furnace.Reported in this paper are the production control design for copper smelting process, and the operation control scheme of the flash furnace following the brief review of the characteristic of Saganoseki Smelter's process and some improvements. Copper Smelting ProcessDescriptions of major unit operations and general specifications of the copper smelting facilities are summarized in Table 1, and the present flowsheet of the copper smelting is described in Figure 1 (1,2).Outputs and raw materials treated in the last five years are shown in Table 2, in which concentrate includes powder copper scrap which amounts to 3 to 4% of concentrate.A full operation was performed for a period of one month, for both one flash furnace operation and for two flash furnace operation. With one furnace operation, 19,200 tons of copper were produced. With the two furnace operation, 84,000 tons of concentrates were charged and 33,500 tons of anode (net 28,600 tons of copper) were produced.The actual production level, however, has been kept at 80 to 90% of the full capacity because of low copper price, tight market of copper concentrate or fall of net demand in Japan."

Jan 1, 1989

By Guangchun Yao, Chuan Li, Hongjie Luo, Zhuokun Cao

"The expansion rate and collapse time of liquid aluminum foams are essential for the determination of operating time and quality of the resulting foam. In the present paper, liquid aluminum foams was fabricated by adding in TiH2 as blowing agent, and the variation of expansion rate with foaming time was non-contact detected by a laser distance measurer. The influence of different stabilizing agent and alloying elements was studied. The results show the fact that the fraction of stabilizing agent only perform little effects on the maximum expansion rate of liquid aluminum foams, while the influence of alloy elements are remarkable. The maximum expansion rate would increase much when Mg is added, and the liquid foam also collapse at a shorter time. Comparison was made between experimental results and mathematic calculations, which reveal the fact that it is the change of TiH2 decomposition responsible for the change.IntroductionMetal foams, combining light weight with other unique mechanical and physical properties, have gained wide interest and been developing fast during past few decades. However, manufacture of this new material is quite challenging since it involves simultaneous occurrence of gas, liquid and solid phase at high temperature [1-2].Quite some manufacture routes have been developed for manufacturing metal foams, and the structure and quality of resulting foam are remarkably improved during the last decades. However, most of the past works seems to be experiential, and because the lack of basic knowledge of foaming process, the start material is limited and the production technologies are far from reliable and reproducible.[3-4]In direct foaming process, decomposition of blowing agents, TiH2 for example, is the main force for foam expansion. The density and foam structure changes with time during the foaming process, so it is expected that foams of certain structure can be obtained by solidification of the liquid foam at a certain time [5-6]. However, the foaming process is weak in reproducibility and the influence of stabilization additives and alloying elements is unclear."

Jan 1, 2011