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By Jr. Loper, M. H. Kim, H. H. Jo, C. S. Kang, T. S. Song

"An investigation has been conducted to describe the effect of grain refiner (e.g.,Ti) or modifier (e.g., Sr) on the microstructure of an Al-11.3wt%Si alloy produced by the Ohno horizontal continuous casting process using a heated mold so as to obtain directional solidification at high cooling rate of 300 to 2000°C/s. Experimental results demonstrated that the directionality of the primary a grain was promoted by the addition of0.2 to 0.4%Ti or by the addition of0.02%Sr, whereas the addition of0.6%Ti suppressed this directionality. Feathery a grains were promoted by the addition of 0.2%Ti, while these feathery a grains were suppressed when over 0.4%Ti (grain refinement) or when 0.02%Sr was added. The addition of Ti also resulted in increased coarsening of the eutectic Si in these Al-1 l.3wt%Si alloys.IntroductionThe mechanical properties of conventionally cast Al-Si alloys can be enhanced through judicious control of the casting parameters, by the addition of grain refiners (e.g., Ti) and by the addition of eutectic modifiers (e.g., Sr).[1-3] The Ohno continuous casting process[4-5] uses a heated mold (maintained at a temperature above the alloy liquidus temperature) to produce a casting with a mirror surface free of shrinkage defects. The process is especially suitable for the production of high quality and non-deformable rods of small diameter. This study was conducted at investigate the effects of Ti and Sr on the microstructure of Al-1 l .3wt%Si rods cast by the 01).no process."

Jan 1, 1998

By Y. Fautrelle, F. Felten, O. Metais, Y. Du Terrail

"We deal with the prediction of electromagnetically-driven turbulent flows by means of a Large-Eddy- Simulation method (LES). The model is applied in the case of a liquid metal pool submitted to a polyphase linear electromagnetic stirrer. We investigate two cases: (i) the frequency of the magnetic field is equal to 50 Hz; in that case the effects of the pulsating part of the Lorentz forces may be neglected; (ii) the frequency of the magnetic field is low (f= 1 Hz), then the oscillating part of the electromagnetic forces is taken into account. The LES predictions agree well with the mean velocity measurements, as does the standard k-a model. However, as for the turbulent kinetic energy predictions, there is a large discrepancy between the two models. When the oscillating part of the Lorentz forces is taken into account, the computations show that the fluid flow is sensitive to the unsteady part of the forces. We find that the mean velocity is not affected by the fluctuating component of the force. As for the turbulence parameters, the presence of the pulsating part leads to a significant reduction of the turbulent kinetic energy, whilst the turbulence length scale decreases.IntroductionElectromagnetic stirring is commonly used in various metallurgical processes. In continuous casting for example, it may improve the structure of the solidified metal products. Fluid flows generated by electromagnetic stirrers have been extensively investigated (1 ). As for numerical predictions, many works have been published on the subject. In most of the previous works, onepoint closure models have been used. The most used model is the well-known k-i:: model. Those models yield fairly good results as for the mean velocity prediction. However, it has two main drawbacks:(i) the turbulence is not predicted accurately,(ii) it is not well fitted for unstationary flows as well as transitional turbulent motions, where theReynolds number is moderate."

Jan 1, 1999

By Chuan-fu Zhang

The fibrous precursor can be obtained by coordination precipitation process, using oxalate, cobalt chloride and ammonia. XRD pattern of precursor precipitated at pH=9.0 is different from that of ß-CoC2O4?2H2O precipitated at pH=1.0 which indicates that the precursor powders are one type of cobalt complex. According to the results of element analysis and IR spectra, it can be inferred that the composition of the precursor is [Co(NH3)x]C2O4?H2O(x=1.2?..6) formed by the coordination reaction at pH=9.00 in the Co(II)-C2O42--NH3-NH4+-H2O system. It?s found that the fibrous cobalt powders greatly inherited the morphologies of the precursors. Many factors could affect the formation of the fibrous cobalt precursor powders, such as the initial Co2+concentration, pH value and so on. The SEM images show how they influence the morphologies of the precursor powders. By adding proper surfactant, the dispersion of the precursor powders would be improved. At last, the final product-fibrous cobalt powders which are about 0.3~0.5min size and 40~60 in aspect ratio were produced by thermal decomposition of fibrous cobalt complex at 400~500°C in the weak reducing atmosphere.

Jan 1, 2006

By L. Becze, S. J. Hock, G. P. Demopoulos

"Regeneration of HCl from chloride solutions is commercially practiced by high temperature (800-900 °C) pyrohydrolysis associated with high energy consumption and capital cost. As an alternative to pyrohydrolysis a novel low temperature ( <200 °C) non-autoclave hydrolytic process has been studied in this research work, which comprises two steps. In the first step, ferrous chloride is oxidized by oxygen at 1;150 °C, followed by hydrolytic decomposition of ferric chloride to coarse hematite particles and superazeotropic hydrochloric acid (8-9M) operated at approximately 180 °C. This paper provides a summary of the laboratory results related to both oxidation and hydrolysis and presents a newly designed conceptual process flowsheet.IntroductionRecovery of base, noble and rare metals from ores and secondary materials (slags, dusts, residues) by chloride-based hydrometallurgical processes holds a lot of promise if a low cost HCl process becomes available. This is particularly so due to the high activity of HCl or more accurately activity of hydrogen ion [1] in concentrated chloride media and the formation of chlorocomplexes allowing for effective leaching under atmospheric leaching conditions and simultaneous ease of metal separation. However, during leaching significant amount of iron, which is associated with most of ores and secondary materials, goes into the solution. Hence, the obtained leach solution has to be treated to convert iron chlorides into easily filterable iron oxide and simultaneously produce concentrated hydrochloric acid. Apparently the critical operation of these processes is the regeneration of the lixiviant (HCl). Currently in the industry, its regeneration is accomplished by high capital and intensive pyrohydrolysis which operates at 700- 900 °C. Aimed at lowering the operational cost of pyrohydrolysis a process called PORI [2] was developed and tested in pilot plant scale in the 1970s for the purpose of treatment of pickle liquors without, however, resulting in industrial application."

Jan 1, 2011

By Alex Moyano

At present, the Codelco Norte smelter processes in the Teniente Converter and the Flash smelting Furnace 1,420,000 t/y of its Chuquicamata concentrate with an arsenic content of up to 1.5%. In a near future Codelco-Chile is considering different processing options for a new projected concentrates from the Alejandro Hales mine (former Mansa Mina mine with an arsenic content of up to 6%). The main option is the possibility to process 3,000 t/d of mixing concentrates from the Alejandro Hales and the Chuquicamata mines, in the Teniente Converter. The main feature of this smelting unit will be high volatilization of arsenic when processing high arsenic-bearing concentrates. The CN smelter staff carried out a technical feasibility study to evaluate the processing of high arsenic-bearing concentrates directly in the Teniente Converter, thus the low arsenic-bearing concentrates can be processed in the FSF. Accordingly, laboratory scale tests were carried out at the Tohoku University facilities. The lab-scale results allowed an industrial scale test at the Codelco Norte smelter to smelt 2,300 tpd of high arsenic-bearing concentrates in the TC and evaluate the metallurgical impact in the smelting, converting and refining areas of the smelter. The main industrial-scale result confirmed the stabilization of the arsenic content at 0.5% in the 70% Cu produced white metal at the test condition.

Jan 1, 2006

By S. Bagchi

The LaNi5-xMnx-hydrides have potential applications in cryocooling devices for non-mechanical method to compress hydrogen gas. Thermal aging behavior of LaNi5-xMnx-hydrides of compositions x=0.4 and x=1.5 has been investigated. The hydriding properties of the La1.02Ni4.6Mno.4 alloy do not change significantly after thermal aging at 453K for 260 hours. X-ray diffraction analyses of this aged alloy do not reveal the presence of any new phases but the Bragg peaks become broader. Line profile analyses show anisotropic microstrains with an average <e2>1/2 value of -5x103. Thermal aging of the other hydride, LaNi3.5Mn1.5 hydride, at 623K for 280 hours, showed significant disproportionation; the hydrogen capacity reduced significantly from an H/M value of 0.75 in the activated condition to -0.15 after aging. X-ray diffraction analyses showed disproportionated lanthanum dihydride, metallic Ni, and Mn phases. The Bragg peaks were very broad indicative of microstrains or small crystalline domains.

Jan 1, 1997

By Kurt Westerlund

The design of the economically most profitable and technically most feasible smelter process gas handing and treatment as an integrated part of the total metallurgical process is discussed and exemplified, with alternative flow sheets including material and energy balances, investment and operating costs. Retrofitting and de-bottlenecking of existing gas handling lines wil1 be described and exemplified. Methods of increasing total gas handling line availability will be described.

Jan 1, 1992

By S. N. Ashrafizadeh

Nowadays, hard carbides have found various industrial application in the manufacture of cutting and drilling tools as well as metal forming devices. About 60% of the world tungsten production is consumed in the manufacture of hard carbide pieces. Regarding the high economic value of hard carbide components, i.e., Ni, Co, TaC, TiC, and WC, their recovery from scrap species is attracting much interest. In the current research, the cobalt and tungsten content were recovered from scrap cemented carbide pieces through the application of high voltage electrolysis in nitric acid media. By this method, cobalt and tungsten were initially recovered as cobalt nitrate and tungstic acid, respectively. The precipitate of tungstic acid was calcined at 800ºC after being washed twice with distilled water. A pure tungstic oxide was obtained. The effects of current density, electrolyte concentration, speed of agitation, and the surface area of the anode on the efficiency of the electrolysis process were investigated. The optimum conditions of current density of 1500 A/m2, an acid concentration of 1.5 M, and a cell temperature in the vicinity of 60 to 80ºC were obtained. At the optimum conditions, an acceptable rate of collapse for the anodic carbide pieces of about 3.1 g/h was achieved, which remained constant up to the completion of the recovery process without any passivation .

Jan 1, 2003

By C. Carreno, A. D. Gonzalez Escarcega, M. A. Neri, A. Martinez –Villafane, O. Cobarrubias-Alvarado

"Waspaloy is a superalloy used to manufacture some aeronautical parts subjected to high temperatures and stresses. During thermo-mechanical processing cracks are generated, causing some parts to be rejected. In order to determine the causes of these cracks, this alloy was characterized using techniques such as chemical analysis, optical microscopy, scanning electron microscopy, and EDX analysis. Heterogeneous grain sizes in the microstructure cause a non-uniform strain distribution in these parts, creating cracks in zones with different grain sizes.IntroductionNickel-base superalloys are important materials for high-temperature service applications. The manufacture of components from these materials is typically based on solidification or powder-metallurgy processes [1]. Solidification techniques comprise either the direct casting of parts or the casting of ingots which subsequently undergo a series of thermo-mechanical-processing steps to refine the microstructure. During solidification, microsegregation is usually unavoidable. The primary solidification product is a disordered nickel solid solution with an fee crystal structure (?). In many alloys, the material which solidifies last is a mixture of ã and an ordered fee phase (? '). In prototypical nickel-base superalloys, the ?'-phase is Ni3(Al,Ti) [2-3].Waspaloy is a superalloy that is used in demanding high-temperature environments in which good creep and fatigue resistance are required. One of the most common applications of Waspaloy is for turbine engine rings. To ensure the required mechanical properties, the rings are usually forged and heat treated (Figure 1). Two distinct types of microstructures are usually found to be attractive for such applications: a) A microstructure with a grain size of ASTM 10 to 14 for tensile strength, ductility, and resistance to crack nucleation in low-cycle fatigue; or b) A microstructure with a grain size of ASTM 4 to 8 required for creep strength and resistance to crack propagation [4]. Because it is impossible to refine the grain size through heat treatment, a skillfully designed forging process is crucial for the control of the grain size and, hence the properties of the forged ring [5-6]."

Jan 1, 2012

By M. Oliazadeh

The present study was performed to develop a process for solvent extraction of molybdenum and cobalt from an acidic solution generated by an electrodeposition process of nanocrystalline cobalt alloys. Solvent extraction is a common practice in hydrometallurgical and refining processes to produce metals; however its application for separation of molybdenum and cobalt from this specific solution is new, because molybdenum and cobalt are not commonly associated together in nature. Five commercial organic extractants were examined for extraction of cobalt and molybdenum from synthetic acidic solutions with pH ranging from 1 to 5. Preliminary results showed that at pH 2, any of the Cyanex 923, Alamine 336, Aliquat 336 and Hostarex A327 could be used to extract 99% of molybdenum from solutions, while from pH 3 to 5, Aliquat 336 was able to extract about 100% of molybdenum. Cobalt extraction, on the other hand, varied from 15% to 23% at pH 3 and 30% to 53% at pH 2 using different extractants. Based on results obtained, Aliquat 336 was applied on mixed solutions of cobalt and molybdenum at various pHs. The results showed that molybdenum could be extracted as much as 99% from a mixture of molybdenum and cobalt at acidic pHs, while less than 1% of cobalt was separated at pH 2 to 4 simultaneously.

Jan 1, 2003

By Junji Shibata

Extraction behavior of Ti(IV) and other metal ions, such as Fe(III), Fe(II), Cu(II), Zn(I1) and Co(I1) from acidic solutions like sulphuric acid and hydrochloric acid was studied in order to recover titanium from the waste solution in Ti02 production. Extractant used was tri-alkyl phosphine oxide whose trade name was Cyanex 923. Then, a study was made of the idea of simulating a countercurrent multistage extraction system, using the results of batch extraction. The simulation was camed out on extraction and saipping behavior for a Ti(1V)-H$O,-Cyanex 923 system. From the simulation result., the optimum operating condition of the system was considered.

Jan 1, 1994

By Luis M. González, Guzmánm Guillermo D., Davis Juan C.

"The Teniente converter (CT) of the Ventanas Smelter and Refinery of Codelco-Chile has two tuyeres for dry concentrate injection directly into the melt.The diluted phase injection system can feed 15 to 20 kg of concentrate for 1 kg of air, which creates a very abrasive solid/gas phase. The tuyeres commonly used lasted for about 3.5 days due to the accelerated decay of the shell, and 1.5 hours were necessary for the replacement of new ones in the reactor.Tests were carried out with common shell tuyeres with a tungsten based welding cover, and a life span of 28 days was reached, increasing the Teniente converter operational continuity between 1.5 to 2 %."

Jan 1, 2009

By Toshia Suzuki, Keiji Kakudate, Yoshihiro Adachi

"A macro model for the steel usage pattern in Japan is proposed. The steels are classified into four types; converter steel for machinery and for construction and electric furnace (EF) steel for machinery and for construction. The steels are assumed to be discharged from the society in accordance with lifetime distributions of each usage. The amount of EF steel and the accumulation in society are calculated using a population balance model. The comparison with the calculated results and statistics ensures the validity of the model. Since the amount of EF steel for construction will increase and be oversupplied, EF steel will have to be used for machinery. The required and available amounts to supply EF steel for machinery are considered from the point of allowable· copper concentration for machinery use. Copper contaminates steel used for machinery during recycling process and contamination ratio is evaluated with the model. Copper concentration in EF steel is predicted for various scenarios.IntroductionThe amount of CO2 emission from Japanese steel industry is 48.0 million C-ton in 1990 and it occupies 15.1% of the total amount in Japan. In order to reduce the C02 emission and to save the natural resources, it is strongly required to promote the recycling of steel. However, the impurity contaminates steel in recycling process and lowers its quality. The copper concentration in EF steel is analyzed by Toi et al. using a macro model with the assumption that steel is discharged in proportion to the accumulation amount [1]. However the discharged amount of products is dependent on their age for service and usage pattern and not on the accumulation amount. In addition, the degree of copper contamination is different depending on the usage of steel. Therefore a precise model that contains the age for service within the society as a parameter and distinguishes the usage· of steel is necessary in order to clarify the problems in the recycling of steel."

Jan 1, 2000

By G. K. Ruhlandt, C. W. Kim

"A 3-D Finite Element Method program called ""SOLCAST"" has been developed to simulate the casting solidification process. Using the temperature recovery method to evaluate the latent heat of fusion and applying a new combination of the time integration scheme, SOLCAST reduces the computational time significantly compared to an existing commercial FEM program, and produces accurate results comparable to experimental casting results. Prediction of casting shrinkage porosity for A390 aluminum alloy will also be discussed. To make this FEM program useful for foundry engineers, this program was connected to a commercial pre- and post-processor.IntroductionBecause of recently increased competition, foundrymen must produce high quality castings more economically. Therefore, casting solidification analysis prior to casting production is an attractive way to reduce costs and development time.Although the actual casting solidification process is a very complicated phenomena, foundrymen could predict where shrinkage defects would occur based on a transient conduction heat transfer analysis that includes the liberation of latent heat. A numerical analysis is generally required to solve the heat diffusion equation with the latent heat diffusion term, because casting shapes are very complicated and pure materials are rarely used.Different numerical methods have been applied to the casting solidification analysis 1. Among them, a finite difference method 2 and a finite element method (FEM)3 are most commonly used.Each simulation method has one or more basic difficulties which are different for each method. These difficulties are:(1) Modeling casting shapes on a computer.(2) Time consuming computation.(3) Uncertain material properties."

Jan 1, 1986

By František Molnar, Zsolt Szentirmai, Juraj Schmiedl, Felix Sekula

"Hydrometallurgical nickel production in Sered Nickel Plant (Slovakia) that treated roasted Albanian ore left behind a considerable amount of the solid leaching residue. About 6 million tons of this fine-powder residue containing approximately 52 wt.% of iron in the form of oxides is to the present day stored in a stockpile. However, its iron content makes it a potentially interesting secondary raw material for iron production. This secondary raw material is not, unfortunately, suitable for direct treatment in iron and steelmaking processes.This paper presents results of the laboratory tests of pyrometallurgical method of processing of the leaching residue by its roasting and subsequent refining melting. The objective of the selective reducing agglomeration roasting was to reduce iron oxides and to simultaneously avoid reduction of chromium oxides and silica. Refining melting is carried out in an inert atmosphere. The products of melting are technically pure iron and slag.IntroductionThe leaching residue stockpiled on waste dump near already non-existing Nickel Plant Sered, Slovakia, is considered to be one of the most important environmental burdens in this country. The 40-years of an on-going effort focused on finding the methods for extracting metals and thus remove the waste dump have not been successful [1,4,5,6]. From the literature survey it is evident that past investigations have been following three main routes:1.Removal of chromium by mineral processing methods prior to its metallurgical treatment to achieve final chromium concentrations below 0.3 wt.%.2.Pelletization of solid leaching residue and its subsequent reduction in blast furnace and steelmaking plant and simultaneous removal of chromium.3.Pelletization of solid leaching residue followed by metallurgical processing of preliminary reduced semi-product in electric arc furnace (EAF) accompanied by partial reduction of chromium."

Jan 1, 2008

By N. R. Green, N. J. Humphreys, D. McBride, T. N. Croft, M. Cross, D. M. Shevchenko

"Centrifugal casting offers a route to high quality products in difficult to cast high temperature low superheat alloys and thin section molds. Under centrifugal forces metal is forced into thin sections and can fill thicknesses of less than a millimeter. However, due to the high liquid metal velocities there is a high risk of surface turbulent flow and air entrainment within the liquid metal. The combination of interacting flow-thermal-solidification phenomena and associated defects is a challenging modeling task which the authors have previously described and validated. Capturing the metal-air interface, on what are inevitably complex three dimensional geometries, results in highly computationally expensive simulations and simulating a single cast can take weeks on a single processor. This contribution reports on modeling a complex centrifugal cast, gas entrainment, bubble transport and solidification, employing meshes of up to a million elements and investigates the scalability of the model on high performance clusters.Introduction The ultimate goal of any casting procedure is to produce a defect-free product. For difficult to cast alloys, such as Titanium, centrifugal casting has a number of advantage over conventional gravity methods [1]. In the casting of thin sections, such as turbine blades, the metal is forced into the thin sections under centrifugal forces. The centrifugal force can overcome the backpressure due to surface tension and the metal can fill mould sections with thicknesses substantially less than a millimeter. However, the materials used in these castings [2] tend to be highly reactive and requires low superheat. High liquid metal velocity gives rise to a high risk of free surface turbulent flow and of associated entrainment through free surface turbulence [3] and trapping of gas present in the flow [1]."

Jan 1, 2012

By T. A. Chepushtanova, B. Mishra, E. O. Kilibayev, V. A. Luganov

"The paper contains the results of studying about modification of pyrite and arsenopyrite specific surface and porosity at their thermal decomposition. The studying of specific surface was carry out by B.E.T. – adsorption of nitrogen at his boiling-point. In our work were using the electron-microscopical, X-ray structure analysis and chemical analysis. There was established that the decomposition of pyrite and arsenopyrite accompany by increasing of pores volume from 0.303 · 10-3 to 1.23 · 10-3 at increasing of pyrite degree of decomposition about 41 % and then decrease about 0.131 · 10-3 m3/g at degree of decomposition near 100 %. The surface area of pores increase from 0.31 to 1.085 m2/g with following lowering due to enlargement and confluence of minor, small pores. Increasing of porosity accompany with increasing of particles windage that appear the result of heightened dust-furnace partially decomposing pyrite and arsenopyrite particles by air flow from furnace reaction zone. This explains heightened contention of sulfide sulfur in roast dust of sulfide concentrate. 1. INTRODUCTION As a result of ore base exhaustion of ferrous and nonferrous metallurgy at metallurgical treatment are involving more complicated and less qualitative ores. Magnetiting ores content considerable quantity of pyrite complicative the technology of iron extraction. At the same time the pyrite concentrates wining at dressing content different nonferrous metals in industrial quantities. Extracting ores of nonferrous metals are contenting considerable quantity of arsenic at the present time. Extraction of base metals from complicated raw materials demands new technologies. Arsenic contenting in ores is necessary to utilize (waste burial) in more ecological compatible form. Arsenic on acting metallurgical and chemical enterprises from technological cycle is withdrawing in the form of arsenate – arsenite cakes, burial of their may lead to seriously ecological problems as times goes by. In Kazakh National Technical University is carry out the cycle of researching by pyrite, arsenopyrite and arsenate – arsenite cakes treatment with the object of arsenic withdrawal in sulfide form – in more ecological and safe form and with the object of preparation of initial ore raw materials to following pyro- and hydrometallurgical treatment. As a result of sulfidizing of arsenate – arsenite cakes by pyrite are forming the volatile arsenic forms and pyrrhotite of variable structure."

Jan 1, 2008

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 Eiki Ono, Atsushi Yamatodani, Shigeru Sunagawa, Yasushi Takasaki, Atsushi Shibayama, Yasunori Higuchi

"During metallurgical processing of non-ferrous metals, smelting residue (inc. smelter slag, flue gas and so on) is inevitably generated as secondary product.In this research, some experimental feasibilities were investigated to recover/remove Cu and As from the residue. Primarily, the removal of As and volatilized materials from the residue was examined by pyrometallurgical treatment (dry-process). In the second stage after treating the residue with a dry-process, leaching and solvent extraction as hydrometallurgical treatments (wet-process) were also investigated by using H2SO4 solution as a two stage leaching treatment, to dissolve various metals from the leach residue. Then, solvent extraction was examined by using LIX-84I as an extractant to recover and separate Cu from impurities from the final (2nd) leached solution. For the leaching stages, the removal of 90 % As and the leaching rate of 85 % Cu could be achieved by 0.25 mol/l and 1.0 mol/l H2SO4 solution, respectively. On the other hand, the extraction of over 90 % Cu and stripping was carried out by solvent extraction. 1. IntroductionIn metallurgical process for non-ferrous metals, smelting residue (inc. smelter slag, flue gas and so on) is inevitably generated as secondary product, i.e., flue dust, slug and so on. The smelting residue includes some useful metals and undesired toxic materials; Cu, Pb, Ca and As, etc.In Japan there is one undisclosed place stockpiled with 10,000 ton of smelting residue from abandoned smelters about 25 years ago. Therefore it is necessary to reduce the residual amount for space and environmental protection including water treatment by separating and removing toxic materials."

Jan 1, 2008

By Ozgul Dere Ozdemir, Muge Sari Yilmaz, Sabriye Piskin, Deren Sibel Kasap

"Galvanic sludge is generated at the end of the waste water treatment process of metal plating system. The waste sludge is one of the main hazardous solid wastes produced by metallurgical industries. It is caused the harm of human health and damage of the environment due to containing reasonable amounts of toxic metals (e.g., nickel, zinc, copper, chromium, iron, lead, cadmium, etc). The concentration of those toxic metals in the wastewater might reach 30% (w/w, dry weight) making their removal and recovery an interesting issue.In this study, synthesized titanium dioxide is used as adsorbent to remove nickel in leachate of galvanic sludge. The adsorption experiments were carried out isothermally at four different temperatures. The effects of pH, temperature, and contact time on nickel adsorption efficiency were investigated, and the optimum parameters were determined from the experimental studies. The experimental results indicated that pH, temperature, and contact time played a significant role on the adsorption capacity of nickel.IntroductionRapid industrialization has caused increasing the heavy metal concentration in biosphere with the industrial wastes. These wastes are generated in various industrial processes such as electroplating. Galvanic sludge is a hazardous waste that generates from metal plating industry by chemical precipitation of heavy metals from acidic or alkaline solutions during the waste water treatment process. Heavy metals are tend to bioaccumulate thus they are treated the living organism [1-2].Galvanic sludge is mainly disposed on landfills for these reason it is a big problem for environment. Galvanic sludge containing nickel (II) is common because nickel (II) is used in electroplating process [3]. In drinking water, nickel may cause health problems if found in amounts greater than the health standard set (MCLG: 0.1 mg/L) by the United States Environmental Protection Agency (EPA). The higher concentration of nickel (II) in ingested water may cause severe damage to lungs, kidneys, gastrointestinal distress, e.g., nausea, vomiting, diarrhea, pulmonary fibrosis, renal edema, and skin dermatitis [ 4]. For these reasons, it must be treated before disposed to landfill."

Jan 1, 2011