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By Garry W. Warren

The brass foundry industry produces a significant amount of waste sand containing Cu, Zn and Pb which is often classified as a hazardous waste due to Pb content. The potential application of a hydrometallurgical process to treat the sand by extracting metal values and thus detoxifying the material has been investigated. The process involves leaching of metal values followed by cementation. The emphasis of this investigation was on the leaching step, although some preliminary cementation experiments have been performed. In order for any alternative treatment scheme to be successful, the smaller size fractions of the sand must be addressed. Experiments have been performed on five individual size fractions using various lixiviants HCI, acetic acid and HCI/NaCI. Cu extraction was found to be slower than either Zn or Pb. Results obtained in this investigation indicate that copper is present in two forms, an oxide form which dissolves rapidly and is insensitive to the level of oxygen, and a less soluble form, probably metallic which dissolves more slowly and requires an oxidizing agent. The presence or absence of oxygen had no influence on the rate of Zn dissolution indicating that zinc is present mostly in oxide form. Toxicity Characteristic Leaching Procedure (TCLP) tests showed that residues could be produced which meet the toxicity limit for lead. Preliminary cementation experiments have also demonstrated the feasibility of Cu and Pb recovery.

Jan 1, 1991

By Laurentiu Nastac

"Two advanced control solidification technologies were studied in this article to improve the quality of the cast ingots as well as to control the solidification structure evolution during the plasma arc melting (PAM) processing of Ti-6-4 ingots: (i) electromagnetic stirring (EMS), and (ii) ultrasonic treatment (UST). The developed EMS modeling approach is based on the numerical solution of Maxwell's equations, fluid flow, and heat transfer equations, and mesoscopic modeling of the grain structure. The UST analysis tool is capable to model acoustic streaming and cavitation. It is used in this work to study ingot solidification under the presence of ultrasound. Predictions of the macrostructure, GET formation and primary dendrite arm spacing for PAM Ti-6-4 ingots processed with and without EMS or UST were discussed.1. IntroductionTitanium (Ti) alloys are melted, refined and cast into ingots through plasma arc cold hearth melting (PAM), electron beam cold hearth melting (EBM) and vacuum arc remelting (VAR) for jet engine applications. Process modeling has become a viable tool to optimize the PAM, EBM, and VAR processes. A comprehensive modeling approach to simulate ingot solidification phenomena in primary melting and secondary remelting processes of Ti alloys would include models for macroscopic mass transfer, heat transfer, fluid flow, acoustic, electromagnetic and species transport. The approach should also include microscopic models to predict the evolution of grain structure in solidifying ingots in conjunction with electromagnetic stirring (EMS) and ultrasonic stirring (UST)."

Jan 1, 2012

By Dong Hoon Han

The simultaneous sulfation by sulhr dioxide and oxygen of CaO and MgO in calcined CMA (calcium magnesium acetate) were investigated. he experiments were carried out in the temperature range from 700 to 830 "C and at the SO2 concentrations of 0.3 to 1 mol %. The oxygen concentration was kept at 5 %. Each sample was calcined completely before the temperature was lowered to the sulfation temperature. According to the ranges of partial pressure of sulhr dioxide and temperature, there exist three regions for the sulfation reaction: region I in which neither oxide is sulfated, region I1 in which only CaO is sulfated, and region 111 in which both oxides are sulfated. It was shown that the MgO in calcined CMA is sulfated at a rate comparable to that of CaO by forming a mixed sulfate phase. Thus, unlike MgO contained in other desulhrization materials, the MgO content in calcined CMA can be fully utilized for flue gas desulhrization.

Jan 1, 1999

By G. A. Eltringham, A. F. Sarofim, A. A. Shook, M. P. Heap, B. R. Adams, K. A. Davis

This paper discusses the use of a reacting CFD model to determine chalcopyrite kinetics in a drop tube furnace and to predict the reaction of a chalcopyrite concentrate in the reaction shaft of an industrial smelter. Reacting CFD codes can be applied to determine the consequences of the interaction of gas with particles and therefore improve the ability to derive kinetic parameters that take into account the different temperature and oxidation histories that different particles will see. This paper describes the application of such a model to derive improved kinetic parameters for the pyrolysis and oxidation of chalcopyrite. The improved kinetic parameters derived from the drop tube studies are used to simulate chalcopyrite concentrate reactions in the reaction shaft of an industrial smelter. The reaction shaft model includes the effects of turbulent fluid mechanics, entrained flow mixing, turbulent particle dispersion, heterogeneous particle reactions, radiative and convective heat transfer, and surface and bath deposition rates. Particle reaction and composition characteristics are predicted as a function of particle trajectory and deposition and are used to aid in evaluating shaft performance.

Jan 1, 1999

By Jiang Diao, Yong Qiao, Xuan Liu, Tao Zhang, Bing Xie

The equilibrium experiments between the FeO-SiO2-MnO-TiO2-V2O3-Cr2O3-MgO slag system and solid pure iron were performed to investigate the vanadium and chromium distribution ratio under Ar atmosphere. The influence of w(FeO), w(V2O3) and w(Cr2O3) in slag on vanadium and chromium distribution ratios were studied at 1653 K. The experimental results were compared with calculated distribution ratios based on molecule and ions coexistence theory. Both of them showed that higher FeO content in slag would improve the distribution ratios of V and Cr between slag and hot metal. The distribution ratio of Cr or V increased with the increase of Cr2O3 or V2O3 content, respectively. To optimize the oxidation of V and Cr from hot metal, a high oxidizing slag and suitable content of Cr2O3 and V2O3 in the slag were recommended. The results provided reference for the further study on the extraction of V and Cr in VTi magnetite.

Jan 1, 2016

By Vladyslav M. Sokolov

The cost effective and environmentally friendly recycling technology was developed and tested. It enables utilization of the fine nickel-base superalloy scrap in a form of heavily oxidized scarfing granulates. The process of granulates generation was discussed in details. Their properties were investigated. The results of literature search showed anticipated sufficient improvement of the properties of cast iron by its alloying with the elements from the scarfing granulates. The novel alloying approach is based on the two stage reduction operation. Firstly thegranulates were partially reduced in a solid state by their exposure with powdery carbon at the range of 1550 ? 1700°C. Then the gotten product was efficiently introduced into liquid iron since it has a form of fine natural agglomerates for arranging the optimal conditions for reduction of the granulates. The thermodynamic evaluation demonstrates higher reduction efficiency of carbon and silicon dissolved in iron than of the same elements in a form of the separate phases. The considered process partially provides itself by energy since the reaction of reduction of the chromium oxide by silicon dissolved in liquid iron has exothermal character. The mostly complete extraction of Ni was received. The sufficient reclamation of Cr was gotten at the same time.

Jan 1, 2006

By Jean-Louis Dirion, Guy Depelsenaire, Patrick Sharrock, Souhila Kribi, Ange Nzihou, Jocelyn Ramaroson

"This study assesses the Novosol® process, an emerging technology developed by Solvay to treat heavy metals from dredged sediments using phosphoric acid. The main goal is to convert toxic metal ions, such as Pb2+, Cd2+, Zn2+ and Cu2+ to insoluble metallic phosphates. The effectiveness of the treatment was evaluated by performing the chemical reaction in a tubular reactor, followed by convective drying and maturation of the treated sediment at ambient temperature and finally thermal destruction of the organic matter by calcinations (500°C-700°C). Selected variables (acid concentration, volume fraction of solids, flow rate, drying and calcination temperature and time) were investigated. Laboratory scale experiments were carried out with various combinations of these parameters. The influence of the quantity of acid and the temperature of calcinations on physical properties of the sediment and stabilization of the heavy metals are discussed. Introduction The French territory counts 525 000 km of rivers which transport each year on average 6 million m3 of sediments. Their deposit causes the silting of channels, rivers and lakes. This completely natural phenomenon is exacerbated by the introduction of industrial and urban wastes into the erosion and sedimentation process. This silting leads to clogging of rivers, with a reduction in their flow rates. Consecutively, other problems appear, such as flooding risks, decrease of biological purification capacity and associated loss of the biodiversity. The presence of toxic compounds (from industrial, household or agricultural origins) in the sediments worsens the situation, and requires curing to restore the natural environment and its function. The dredged sediments are either spread on agricultural land, land tipped, confined or sent for chemical or physical treatment [12]. The first research programmes on toxic sediments appeared at the end of the Eighties in the United States, in Canada, in the Netherlands and in Germany. Several techniques of treatment were developed for the sediments; these techniques can be used alone or in combination. These techniques include extraction and concentration of the pollutants: the pollutants are isolated from the sedimentary matrix and the sediment is decontaminated. In some cases of organic contaminations, the pollutants are destroyed by chemical oxidation or biodegradation and in other cases, the contaminated material is either stabilized (mixed with hydraulic binders), or destroyed (incineration) [14,15]. Phytoremediation by afforestation has also been reported [19]."

Jan 1, 2008

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 Snehanshu Pal

"Concrete understanding of fluid dynamics properties inside basic oxygen furnace (LD converter) and hot-metal surface deformation due to impinging oxygen jet is important for optimization of reaction kinetics and maximization of productivity and refractory lining life. In this study various k-å turbulence models and volume of fluid (VOF) method have been used to model fluid flow and interaction of impinging oxygen jet with hot metal for an industrial scale top blown LD converter.RNG, standard and realizable k-å turbulence models are used to study velocity magnitude, stream function, turbulence intensity profiles. Turbulence kinetic energy, turbulence eddy dissipation, velocity magnitude and probable mixing time have been calculated in three locations inside the converter.The average rate of oxygen jet penetration, location of vortex formation, centre line and superficial velocity of impinging oxygen jet, probability of emulsifícation are studied by VOF method.These simulation studies provide better understanding of phenomena inside LD converterIntroductionComputational fluid dynamics (CFD) modeling in the field of basic oxygen steelmaking can improve substantially the understanding of existing processes where investigation of liquid steel flow measurement is hardly possible due to the rough ambient circumstances. In order to reasonably predict gas stirring operations and emulsifícation, mass, momentum, energy transfer and dynamic interaction among ions, atoms, molecules in the bath, detailed information on flow patterns, fluid velocities, and turbulent properties is essential. Concrete understanding of bath fluid dynamics inside basic oxygen furnace is also important for optimization of reaction kinetics inside the bath and maximization of LD converter lining life."

Jan 1, 2012

By P. Hajiani

Rare earth elements (REEs) are critical materials in many leading-edge technology products. However, REE separation outside China has remained a challenge in addressing environmental concerns of current production. The author has worked on a technique employing the emphasised variability in the electrophoretic mobility (μi) of REE for the purpose of REE separation. In continuation of the results presented in IMPC 2016 [1], this contribution summarizes the progress achieved in 2016 and 2017. The major goal was to increase the REEs concentration by a factor of 1000 and to attenuate the consequent drawbacks, specifically joule heating effect. Amphiprotic hydroxylic solvent was selected to replace water, which has a major impact on the complexation mechanism and buffer requirement. Non-aqueous media result in a significant drop in the specific molar conductivity of the electrolyte, whilst μi reduces several times only. Moreover, a quasi-steady state electrophoretic separation in conjunction with temperature gradient focusing is adapted to improve scalability.

By Himaki Nakano, Kenji Hara, Toshiaki Tsuru, Shunsuke Kawano, Takeshi Ohgai, Hisaaki Fukushima, Shigeo Kobayashi, Tetsuya Akiyama

"Electrodeposition of Fe-Ni and Zn-Ni alloys from aqueous solutions is one of the well-known examples of anomalous codeposition in which less noble metal deposits preferentially. In this paper, the electrodeposition behavior of these alloy systems was compared between the methanol and aqueous baths. In Fe-Ni system, the significant suppression of the deposition rate of more noble Ni was observed over a wide range of electrolysis conditions in both methanol and aqueous baths. However, the electrodeposition of Zn-Ni alloys showed the typical feature of normal type codeposition in the methanol baths, which was completely different from that in aqueous sulfate baths. The difference in the electrodeposition mechanism between Fe-Ni and Zn-Ni alloys was discussed on the basis of the alloy deposition behavior in the baths in which the activity of water was varied:INTRODUCTION'It has been well known that Fe-Ni alloys show an excellent soft magnetic property. Therefore, thin films of this alloy have been used to fabricate the'-various magnetic devices. For the production of Fe-Ni thin films, dry processes such as sputtering, PVD and CVD are 'employed frequently and the resulting films showed a preferable property as a magnetic material. Electrolyses as a production technique of thin films, on the other hand, has the advantage over other processes in its cheaper production cost due to the simplicity of the production unit The Zn-iron-group metal alloys such as Zn-Ni and Zn-Fe electrodeposited on a steel sheet ale known to exhibit excellent corrosion resistance and therefore the electrodeposition of these, alloys has been applied to the production of surface treated steel sheets mainly for automotive body panels.According to Brenner (1), the electrodeposition behavior of Fe-Ni and Zn-Ni alloys was' classified into the' 'anomalous type. In this type of codeposition, less noble metal, i.e. Fe for Fe-Ni and Zn for Zn-Ni system, deposits preferentially and the change in -the alloy composition- with the variation of electrolysis conditions was unpredictable because of their obscure deposition mechanism. Since most properties of the alloys mainly depend on their composition, the composition of the deposited' alloys must be controlled strictly. Therefore, it is neces5al)' to clarify the mechanism of anomalous codepasition in Fe-Ni and Zn-Ni systems: Several mechanisms have been proposed so fur, and among them the hydroxide .suppression mechanism (2), (3) has been regarded most plauslble depend on their composition, the composition of the deposited' alloys must be controlled strictly. Therefore, it is necessary to clarify the mechanism of anomalous codeposition in Fe-Ni and Zn-Ni systems: Several mechanisms have been proposed so far, and among them the hydroxide suppression mechanism (2), (3) has been regarded most plausible. According to this mechanism, it can be predicted that the codeposition behavior depends greatly on the characteristic of water solvent in this study, using methanol as a solvent, the electrodeposition behavior of the anomalous codeposition was investigated to discuss the validity of the hydroxide suppression mechanism."

Jan 1, 2000

By C. F. Ferron

A process has been developed to treat the copper gold ores from the Guelb Moghrein mine in Mauritania. The process consists of pressure leaching the sulphide concentrate, neutralising with the oxide ore, recovery of copper by SX/EW and of gold by cyanidation of the autoclave residue. This paper focuses on the pressure leaching step, and presents data from bench and pilot plant test programs. In particular, attention is drawn to the effects of temperature, grind size, neutralisation, retention time and solution recycle on the kinetics of copper dissolution from various flotation concentrates. Likely leach mechanisms are briefly discussed.

Jan 1, 2000

By Ann M. Hagni

Reflected Light Microscopy (RLM) And Scanning Electron Microscopic-Energy Dispersive Spectroscopic Analysis (SEM-EDS) Study Of Electric Arc Furnace (EAF) Dusts Have Shown That Their Mineralogy Is Complex And Varied. The Particles Are Largely Spherical, And Can Be Seen In RLM Sections To Be Composed Of Franklinite, And Zincite, But They Show Significant Solid Solution With Each Other And May Contain Small Amounts Of Chromium. These Crystalline Phases Occur As Crystals And Skeletal Growths Within Ca-Fe-Si Glass. Because Chlorine Is A Deleterious Constituent In Recovered Zinc Products From EAF Dusts, Special Attention Has Been Given To Chlorine-Bearing Phases, And They Include Hydrophylite (Cacl2), Lime (Cao), And Organic Phases. Pyrohydrolysis-Treated EAF Dusts With Silica (Si02), Tungstite (W03), Alumina (A1203), And Bunsenite (Nio) Additives Contain Franklinite, Scheelite (Cawo4), Willemite (Zn2SiO4), And Hematite (Fe2O3)

Jan 1, 1992

By John Frederick Colloghon, O&apos

Bulong remains the only hydrometallurgical process plant in the world that recovers nickel and cobalt directly from high pressure acid leach (HPAL) laterite leach liquors without need for precipitation of an intermediate product (e.g. sulphide, hydroxide or carbonate). Direct solvent extraction (DSX) of both nickel and cobalt in combination with electrowinning of nickel has been operation at Bulong since early 1999. Focus in the first years has been on ramp-up and resolution of commissioning problems. More recently the focus has been on de-bottlenecking and process optimisation. A number of significant process problems have been resolved, the most difficult being the formation of gypsum in the nickel solvent extraction circuit. Sound control of process chemistry is essential to ensure the production of high quality nickel and cobalt products at the lowest possible cost. This paper describes the numerous changes and enhancements to the process chemistry and plant equipment at Bulong and discusses the importance of ore leach chemistry on downstream impurity metal removal. Potential additional enhancements to further reduce unit costs are also presented.

Jan 1, 2004

By E. Yegan Erdem, Fiona M. Doyle, Alyssa A. Maich

"There is an expanding interest in synthesizing high quality magnetic nanoparticles, most notably for biomedical applications. Different processing routes have been reported for the synthesis of magnetite and maghemite. However, some ambiguity remains on their precise chemistry, intermediates, and final products, due to the structural similarity of maghemite and magnetite, and the relative ease of redox transitions during synthesis. Here we present the results of TEM, x-ray and electron diffraction, and SQUID studies aimed at characterizing the products from two different reaction systems, thereby clarifying the reaction chemistry. The first system hydrolyzed aqueous FeCh and FeCb chlorides with ammonia in a micro fluidic reactor at ambient temperature; although the reaction product displayed a uniform distribution, it included non-magnetic goethite and lepidocrocite. If the aqueous solutions contained dissolved oxygen, there appeared to be extensive oxidation of Fe(II). The second system thermally decomposed iron (III) acetylacetonate in ether. In prior studies, oleylamine has been reported to serve as both a reducing agent and capping ligand to control particle characteristics; however, our studies revealed little reduction, with maghemite dominating the reaction products.IntroductionMagnetite and maghemite nanoparticles are co=only used in ferrofluids, in medical applications, and in drug delivery. Superparamagnetic properties, along with low cytotoxicity, colloid stability and bioactive molecule conjugation capability, make these nanomagnets ideal for both in-vitro and in-vivo biomedical applications [1]. One of the major constraints on widespread adoption of nanoparticles for these applications is the amount needed. Typical batch synthesis methods produce polydispersed nanoparticles, which require further size selection procedures to isolate the mono disperse nanoparticle population needed for many applications. In order to maximize the yield of usable particles from a synthesis operation, the reaction conditions must be closely controlled. This requires full knowledge of how the reaction conditions control the various aspects of nanoparticle growth. Many methods have been used to synthesize iron oxides, including sonochemical reactions, mechanochemical synthesis, hydrolysis and thermal decomposition. This work examines the latter two methods, focusing on oxidation and reduction of iron."

Jan 1, 2012

By Dan Wang, Qian Li, Yong-bin Yang, Tao Jiang

"Thiosulfate is one of the most promising non-cyanide lixiviants for gold leaching. However, the undesirable reaction between thiosulfate and copper (II) gives rise to increased reagent consumption, which results in high cost and huge limit to its development. This paper presents study on the effect of ammonia, copper (II) and Cu(NH3)l+ ions on the oxidative decomposition of thioulfate. It shows that the presence of copper (II) and Cu(NH3)l+ can significantly increase the thiosulfate oxidation, while ammonia is relatively unaffected. The oxidation of thiosulfate by copper(II) in the absence of ammonia is fast at first and then decreases as time increased within a certain time, which can postulate that an intermediate product is responsible for the decreased consumption. The effect of ammonia is depended on the interaction with copper (II), which was found to significantly affect the consumption of thiosulfate.IntroductionFor over one century cyanidation is widely used in industrial production of gold, due to its simplity of process and low cost of production. However, cyanide is a highly toxic chemical reagent used dangerously and brings serious environmental pollution. What's more, cyanidation has slow speed of leaching gold and poorly leaching effective for refractory ores. With the exhausting of free-milling gold ores and promoted environmental protection requests, the disadvantage of cyanidation becomes a growing problem. In recent years, more and more research activities have been focused on alternative processes using non-cyanide lixiviants. Among the non-cyanide lixiviants, thiosulfate is considered as the most promising one[l-5].Compared to cyanide, thiosulfate is an inexpensive, nontoxic and less-pollution reagent, which can form complexes with many metal ions. Thiosulfate leaching of gold has an acceptable leaching rate and is insensitivity to impurities. Moreover it presents advantage on the treatment of refractory gold ores such as carbonaceous gold ores, copper gold ores, complex arsenic and sulfur gold ores, and so on[6]."

Jan 1, 2013

By Guo-Sen Zhu

Research on the formation mechanism and control of corner transverse cracks was carried out. The optical microscope and SEM were applied to analyze the characteristics of cracks. It is found that the cracks occur at the relatively lower temperature due to unbending strain and have almost nothing to do with the mold cooling and powder. The keys to prevent corner transverse cracks are to optimize the corner temperature of slab and maintain the good state of casting machine. Increasing casting speed and decreasing the cooling water flux at the corner in the unbending segments, resulting in mild cooling, were applied during investigation to control corner temperature above the upper limit temperature of the No.3 brittle zone of Nb-contained steel tested by Gleeble-1500 system. As a result, corner transverse cracks were minimized, but centerline segregation got worse. And then increasing the cooling water flux at the corner (intensive cooling) was applied to make corner temperature below the lower limit temperature of the No.3 brittle zone. Great diminution of both corner transverse cracks and centerline segregation was achieved finally.

Jan 1, 2006

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 Larry Southwick

This paper covers technical and other developments during the first 20 years of Peirce-Smith converting. There were numerous mechanical and process ideas and concepts already being developed and used by others that had possible application within the converter that Peirce and Smith were moving ahead with. There were also other converter configurations in which the basic lining and larger size concepts could function. Finally, as awards and honors began to accumulate, there were those who felt that contributions of other early workers were being ignored. The working out of these conflicts and differing directions will be described.

Jan 1, 2009

By Shaohua Ju, Huang Chang-yuan, Lu Shuaidan, Peng Jin-hui, Wu Guoqin, Yaqian Wei, Zhang Li-bo

"The contrastive studies of microwave and conventional roasting copper residue from zinc hydrometallurgical was carried. The experimental results showed that the microwave roasting has the higher dechlorination rate in the same condition such as temperature, heat preservation time and atmosphere. When the samples with 100 mesh grain size, the Cl content turned from 14.27% to 1.33% and the dechlorination rate achieved over 90% at 400°C with 2h microwave roasting. And in the same conditions, the materials' dechlorination rate after conventional roasting just reached around 78%. The phase changes of the roasting process was investigated with X-ray diffraction analysis.IntroductionCl element can be accumulated gradually in the solution of Zinc hydrometallurgical system. When Cl content in electrolysis solution comes up to 100 mg/L, the stability of electrodeposits process would be severely affected [ 1]. It would not only accelerate the consumption of cathode and anode plate, elevate the power consumption, but also cause serious corrosion of device, increase production costs and lower the quality of electrolytic zinc [2]. Thus, C1- contained in the solution should be removed before electrodeposits."

Jan 1, 2013