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By I. Gaballah

Decontamination of synthetic solutions of copper acetate, chloride, nitrate and sulfate containing 10, 100 and 1000 ppm of copper, using chemically treated barks has been studied. Metal percent removal from solutions depends on the pH and the initial concentration and to some extent on the salt used. It varies from 40 to 99 % of the solution initial metallic ion's content. The maximum retention capacity of the treated bark varies from 31 to 43 mg of Cu per gram of dry modified bark. Bark loaded with copper had been analysed by Scanning Electron Microscopy and lnfra Red spectroscopy. Cu is uniformally distributed in the bulk of the bark. No copper segregation is observed. It seems that copper is bound to the acidic sites of the bark. Anions are not detected on the copper loaded bark neither with the SEM or with the IR spectroscopy.

Jan 1, 1993

By Michael F. Kitto

The production of sulphuric acid at base metals smelters is predominantly an involuntary activity and now comprises approximately 17% of all-forms sulphur supply in world terms. The majority of elemental sulphur is also produced involuntarily in response to environmental regulations regarding emissions from hydrocarbon processing plants. The paper examines the points of similarity and difference in the sulphur and smelter acid markets, and reviews their interactions. The reasons for the merchant acid market collapse of 1993 are analyzed, and the prospects of a recurrence are considered.

Jan 1, 1996

By Sasa Djokic

In developed countries, the difference between demanded and produced quantities of non-ferrous and rare metals are compensated by secondary raw materials recycling and reprocessing of by-products from both ferrous and non-ferrous extractive metallurgy. Utilization of non-ferrous and rare metals from the metallic secondary raw materials is very significant, both for recovery of the metal value and contribution to the environment protection. Similar to all non-developed countries, the extractive metallurgy in Serbia was based on available natural resources and not so strict environment protection regulations, which was either insufficient or completely absent. Today, Serbia is at the beginning of development of efficient and economical technical and technological solutions in order to ?ecologize? technogenic systems by waste materials, secondary raw materials and degraded soils regeneration (by recycling and revitalization). Several metallurgical technogenic systems in Serbia, together with secondary raw materials classification according to their potentiality for metal extraction by using the existing technologies and expected economical and ecological effects of recycling, are discussed in this paper.

Jan 1, 2005

By Andrzej Warczok

Liquid slags produced in smelting of copper concentrates contain copper in a dissolved form as well as mechanically entrained inclusions of copper matte. Coalescence and sedimentation of inclusions during slag cleaning plays a key role in copper recovery. Liquid matte inclusion in a molten slag presents a system of metallic conductor in an ionic solution. Constant electric field induces migration of the matte droplet along the current lines. Additional phenomena occur in a system under crossed electric and magnetic fields. Electromagnetic buoyancy force acting on the inclusion affects its settling rate. Electromagnetic buoyancy force of insulating and metal spheres has been measured in a liquid synthetic slag. It was found that depolarisation of the metal sphere, related to the electrode reactions occurring in the surface, plays an important role in the determination of the direction and magnitude of the electromagnetic force. On the basis of the existing theories and results of measurements a mathematical model describing the behaviour of metallic inclusions in the liquid slag under the influence of crossed electric and magnetic fields was developed. Simulation of behaviour of copper matte inclusions under crossed fields showed trajectory of motion in a liquid slag as a function of the slag properties and the inclusion size.

Jan 1, 2003

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 David R. Brosnahan

Increased Cu grades due to chalcopyrite-rich ore from The Doe Run Company's new Casteel Mine prompted a program to increase Cu recovery. Preliminary tests indicated that prohibitive quantities of FeS2 float with chalcopyrite. Point counting of mill stream samples showed that locking was not a major problem, although grinding to finer particle size enhanced the floatability of both chalcopyrite and marcasite. Backscattered electron images and microprobe analyses of FeSz minerals revealed the presence of Pb which appears to occur as solid solution in marcasite, and as a sub-micron particulate Pb phase in pyrite.

Jan 1, 1987

By Yanhui Liu, Xuewei Lv, Pingsheng Lai, Chenguang Bai

The purpose of this paper is to study the effect of slag basicity on the Si content in stainless steel master alloys prepared by smelting reduction of Fe-Ni-Cr sinters. Theoretical analysis focusing on the gas, slag and alloy phases of the smelting reduction process at 1600°C was carried out by thermodynamic calculation software----FactSage, showing that the increase of CaO within the slag can result in the decrease of Si within the master alloy. Experiments were also carried out in vacuum melting furnace at 1600°C , and chemical analysis method was used to detect Si content in the alloys. When the MgO content is 9.00%, the experimental results were consistent with the calculated values. However, when the MgO content rises up to 14%, the content of Si in the alloy reaches the maximum when SiO2 equals to 22.81%.

Jan 1, 2016

By J. Grogan

Leaching of galvanized steel coatings allows the steel substrate to be used as a zinc-free scrap source to steel and iron furnaces. In this study the behaviors of sulfuric acid leaching solutions are investigated. The ranked significance of the variables are shown to be acid concentration > temperature > zinc concentration. Examination of the leaching mechanism finds the rate-limiting step to be the cathodic hydrogen reduction reaction. This rate is not only influenced by acid concentration, but also by the hydrogen reduction exchange current density. Dezincing leaching rates are improved by taking advantage of the higher exchange current density of the iron substrate versus the zinc coating. This is accomplished in practice by increasing the exposed interfacial zinc:iron surface area through shredding. Also, a leach control mechanism is proposed through online monitoring of the zinc-iron couple mixed potential.

By P. Ruz

A melt transfer ladle was 3D modeled by means of a mathematical fluid dynamics and heat transfer program. Internal temperature profiles were calculated as a time function for a normal ladle and for a pre-heated refractory lined ladle. It was shown that in a normal ladle the molten metal cools down quickly forming accretions. By using an inner lining there are practically no accretions build up within a typical time of operation. Therefore, by applying a refractory lining to a melt transfer ladle and keeping it at a moderate to high temperature it is possible to reduce cold dope circulation in the smelter.

Jan 1, 1999

By Christophe Thiébaut

Keywords: Pyrochemistry, Salts Treatment, Distillation The pyrochemical purification of metal generates spent salts. When this metal is an actinide such as plutonium, the slags cannot be discarded and are thus disposed in nuclear facility. In order to handle with these slags, the decision has been taken to reduce stored quantities. The development of a pyrochemical treatment is in progress in the CEA Valduc centre. The feed salt, typically composed of various Pu and Am species contained into monovalent or divalent chloride matrix, is first oxidized to convert the actinides into oxides. Then the chlorides are separated from the actinide oxides by vacuum distillation. Temperatures higher than 750°C for monochloride salts mixture NaCl/KCl and higher than 1100°C for divalent CaCl2 base salts, are required to produce an industrial flow of vaporization. Inactive qualification of the process for NaCl/KCl base salt has been carried out with lanthanide surrogates. Then, a pilot equipment, called distillator has been designed and built for production-scale distillation of NaCl/KCl and CaCl2 oxidized plutonium salts. Industrial flows of vaporization have been obtained with this pilot equipment : about 4 g/cm²/h for NaCl/KCl at 800?900°C and 1 Pa, and more than 1,5 g/cm²/h for CaCl2 base salts between 1000?1200°C at 0.1 Pa. The last step, now in progress, is the integration of the distillator into a glove box.

Jan 1, 2005

By Oleg I. Platonov

The process for desulfurizing coke oven gas in a regenerative system ?scrubber-stripper?, with sour gas being fed to Sulfur Recovery Unit (SRU) and tail gas being recycled to raw coke gas scrubber, has been developed. A key problem of this process is the presence of elemental sulfur in the SRU off-gas, which may deposit on gas-blowing equipment, thus disrupting its operation. A new treatment technology for SRU off-gas that has been worked out for a Claus unit operated by «Russian Metallurgical Company» (RMC) in Magnitogorsk (Russia) is presented. It incorporates a catalytic hydrolysis/hydrogenation stage, where all sulfur-bearing species such as sulfur dioxide, carbonyl sulfide and elemental sulfur are converted to hydrogen sulfide. The SRU in Magnitogorsk comprises three main units: gas re-heater; catalytic hydrolysis reactor and waste gas cooler. Re-heater is required to increase temperature of the process gas up to a level of catalytic conversion (beyond 330-3500C). Oxygen utilized as an oxidizing agent reduces the volume of waste gas to a minimal possible value. The operational data garnered since 16.07.2004 clearly shows that the new technology allows high-level purification of Claus tail gas from elemental sulfur. Unlike SCOT ? process, this technology does not require separate stages for H2S removal and enrichment that tangibly simplifies its implementation at lower capital and operation expenditures.

Jan 1, 2006

By L. B. Tsymbulov

Sulphide melts formed in the course of smelting of nickel and copper-nickel feed (matte) actually are sulphide-metallic melts since sulphur contained in the melts is in deficiency with respect to metals. The level of metallization is rather relevant feature of sulphide melts and is widely used in calculating material and heat balances for pyrometallurgical processes. Despite of the above parameter? importance, the investigators have no single opinion on what should be understood under metallization level and the method of its determination. In the present study we present the results of our own experimental and theoretical researches that have allowed determination of some mechanisms of sulphide melts? crystallization. Based on the mechanisms revealed new scientifically justified approach has been offered for determining level of metallization of the components present in sulphide melts. It has been demonstrated that sulphur distribution between the melts is substantially different from generally accepted concept.

Jan 1, 2006

By M. Misra, J. Nanor

The precipitation and removal of arsenic from process waters can be accomplished with addition of lanthanum chloride alone or in conjunction with ferric sulfate. The long term stability of these corresponding precipitated compounds is critical from the disposal stand-point. In this paper the characterization of ferric, lanthanum and lanthanum-ferric arsenate compounds formed at room temperature in acidic and alkaline pH is presented. The characterization techniques used included zeta potential, XRD and SEM. Zeta potential measurements of ferric and lanthanum hydroxides in the presence of arsenate indicate that oxyanions of arsenate are chemically adsorbed onto the positively charged surfaces of these hydroxides. In alkaline pH there is desorption of arsenate species from the ferric hydroxide surface, hence the product is thought to be unstable. On the contrary, lanthanum arsenate is stable in alkaline pH. XRD patterns show that the ferric arsenate formed in acidic and alkaline pH is amorphous, whereas lanthanum arsenate and lanthanum-ferric arsenate formed in acidic and alkaline pH are crystalline.

Jan 1, 1999

By Onuralp Yucel, Ahmet Turan, Murat Alkan, Hasan Ozer

SHS (Self-propagating High-temperature Synthesis) is one of the important methods to synthesize B4C powders. The process contains the reaction of boron oxide powders (B2O3) with magnesium reducing agent and carbon black carburizer. SHS products are leached in HCl media to purify synthesized B4C powders in the following step. In the present study, effects of various functional additives (KClO3, KHSO4, MgSO4.7H2O, NaCl, MgO and Na2SO4) in the SHS stage were carried out. Various proportions of the additives were mixed with the initial SHS charge mixtures. Two different molar ratios were employed in the initial SHS mixtures as 1:3:0.8 B2O3:Mg:C and 1:2.5:0.8 B2O3:Mg:C. After the SHS step, HCl leaching process was applied to the SHS products. Filter cakes were dried and characterized by using X-Ray Diffraction Spectroscopy, BET and chemical analysis techniques.

Jan 1, 2015

By Vojteh Leskov?ek

The tribological load is the load on forging tools resulting from the relative motions between the plastically deformed workpiece and the die. In comparison to many other forming processes hot die forging has an especially disadvantageous tribological system. The advantages of the application of hard coatings, which are well known for cutting tools, are to a much lesser extent explored for casting, extrusion, molding and forging tools. Increasing the lifetime of these tools is an important task in surface engineering because of the complex loading conditions and often complicated tool geometry. The plasma-assisted chemical-vapor-deposition (PACVD) technique is well suited to depositing hard coatings onto large dies and molds. The aim of this study is to present and discus results obtained on a duplex PACVD hard coating in an industrial application like the hot forging of automotive parts. A new generation of vacuum-melted and remelted (VMR) hot-work tool steels has been developed; these can reach a hardness of 58 HRc, and have a fracture toughness at this hardness equivalent to that of standard hot-work tool steels at 45 HRc. This offers one of two advantages: the steels can be used at the higher hardness to provide resistance to wear or deformation, or, when used at a hardness of 47?49 HRc for hot forging, to provide temper resistance, nitriding behavior and adhesive wear resistance. The results presented here are from a preliminary investigation. The experimental results indicate that the introduction of a proper duplex PACVD hard coating will lead to an improved wear resistance and a longer lifetime for the hot-forging dies. Furthermore, by using a hard, low-friction coating excellent anti-sticking properties can be obtained. At this stage of the investigation it is also necessary to carry out pilot trials to determine the wear resistance and the tool life in practice.

Jan 1, 2006

By Abhoy Mukherjee

The Luanshya Smelter is a traditional Reverberatory Smelter which once worked with up to three coal-fired reverbs, and now operates one Reverb and one hot Peirce- Smith Converter, projected to produce approximately 42.000 tons per year of copper anodes. The aim of this study is to select a smelting technology which best fits the upgrading of the Smelter, such that low capital and operating costs are achieved for the projected design production capacity of 60.000 tpy, limited by the available supplies of concentrates. An equally important requisite is the compliance of present and future environmental regulations, which determines the need to install and Acid Plant to treat the smelter primary gases. In the process selection study, the following technologies were analyzed, at a Conceptual Engineering level: the Oxy-fuel Burner Reverb, the Teniente Converter, the CONTOP Cyclone Smelting Reactor, and further, the Ausmelt Furnace, the engineering of which was provided by the proprietary firm. The engineering of the other processes was developed by INDEC, which also integrated the comparative analysis of the four options. The analysis of a comprehensive set of technical factors, including integrated smelter metallurgical models, together with the evaluations of economical features, led to the selection of the CONTOP Smelting Technology for the modernization of the Luanshya Smelter.

Jan 1, 1999

By John K. Wright

The segregation process involves heating oxide-type ores with a halide salt in the presence of a solid reductant. By a complex series of cyclic vapour-phase reactions, the desired metal is extracted from its original position in the ore and segregated to the vicinity of the reductant. In this form it is then amenable to concentration by physical methods. In this work the segregation behaviour or eight different nickel laterite ores has been examined using a laboratory rotary kiln. It was found that the silicate (serpentine) ores responded better to the segregation conditions used than did the limonitic ores. An examination of the segregated metal particles showed that they consisted of ferro-nickel. The concentration of nickel in the metallics was sensitive to the ore types and the segregation roasting conditions.

Jan 1, 1994

By V. I. Lakshmanan, R. Roy

"TiO2 is used in paints, plastics, rubber, paper, inks, textiles and other miscellaneous applications. The demand for the pigment grade Ti02 is growing at 3.0%/year on average and this invites the development of innovative and cost effective processes. The current processes are not designed to recycle the reagents and thereby discharge the effluents into the environment, causing an environmental concern.During this study, synthesis of TiO2 from an ilmenite concentrate was investigated using an innovative atmospheric mixed-chloride leach process. The solution purification was carried out using solvent extraction in two stages. In the first stage iron removal was carried out and in the second stage titanium was extracted. The strip solution obtained from the second stage solvent extraction contained the purified titanium and from this stream pigment grade Ti02 was recovered. The barren solution was used for reagent recovery and the regenerated leach liquor was recycled."

Jan 1, 2011

By Huimin Lu, Liyuan Zhao, Zhijiang Gao

The aluminum matrix composite reinforced by graphene was successfully fabricated using high pressure torsion (HPT). With only 0.5wt% graphene, the grain size was reduced to 100nm while that of pure Al was about 500nm. The hardness of the composite increased from the center (64HV) to the edge (120HV) of the sample. Moreover, the tensile strength of this composite reached 197MPa, while that of pure Al was 157MPa. The enhancement in mechanical properties was induced by grain refinement, load transfer from the matrix to the reinforcement and dislocations piled up at the grain boundaries.

Jan 1, 2015

By Ki Joo Sim, Sung Beom An, Joonho Lee, Minsoo Shin

Valorization of the electrical arc furnace oxidizing slag by coke was carried out by the reduction of iron oxide in the slag. Since the reduction of iron oxide by solid carbon is an endothermic reaction, supply of heat energy is required. In addition, slag has a low thermal conductivity; traditional fuel injection is not suitable for this reaction. Microwave can be used to supply heat energy to the system. Commercial oxidizing slag was reduced by coke under the microwave irradiation (1.7 kW, 2.45 GHz). The maximum recovery ratio of iron was 87%. In addition, slag composition modification was attempted to use the remaining slag for a mixture in cement clinker. Free-CaO in the slag was successfully suppressed, and the use of the remaining slag as a potential mixture was confirmed.

Jan 1, 2014