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By Yuanbo Zhang, Daoyuan Zhang, Youlian Zhou, Guanghui Li, Tao Jiang

"Modified humic acid (MHA) has been developed by Central South University (CSU) and authorized in China. It has been reported that MHA is an effective binder for oxidized pellets prepared from specularite concentrates. In this research, effects of MHA binder on roasting behaviors of the specularite pellets are studied. MHA is an organic binder, containing much carbon, hydrogen, oxygen, etc. During the roasting, MHA can provide some heat because of combustion of hydrocarbon, which is beneficial for the recrystallization of Fe2O3 in the specularite pellets at high temperature. Simultaneously, part of hematite particles within the pellets are firstly reduced to magnetite, then, magnetite is oxidized into secondary hematite, which obviously improves the roasting performance of specularite pellets.IntroductionOxidized pellets have been widely used in steel production as a kind of high quality burden for blast furnace ironmaking [1]. In recent years, production of oxidized pellets is developing very fast. Therefore, the supply of high quality magnetite concentrates, which is the most suitable for pellet production, becomes scarce. It is imperative to pursue new alternative materials for oxidized pellet production [2]. Specularite concentrates have attracted widespread attention due to the advantages of high total Fe grade and low impurity content. However, due to the poor ballability and firing performance, specularite has not yet been widely applied into pellet production [3, 4]."

Jan 1, 2012

By C. Ramasamy

The tariff reductions on imports, as a part of on-going liberalisation process in India, has fueled competition within and outside India and has, in turn provided an opportunity to reach global markets. This change calls for quality upgrades and cost-competitiveness without impairing the environment. In this context, gas based processes, contributing to improvement in quality and environment as well as processes where controls are applied when gases inimical to environment are involved, are discussed in a remelt/cast-house scenario. The impact of such processes on fabrication cost of sheet ingot is seen alongwith consumption and cost of materials and compared with a world class standard plant in North America.

Jan 1, 1996

By Masahiro Hirasawa

"As a fundamental study on pyrometallurgical process that involves recycling steel-making dusts, of which major components are oxides of Zn and Fe, and waste polyvinyl chloride simultaneously ·at. a temperature below 1273 K, the reactions between the mixture of ZnO + Fe20 3 and PVC or the compound ZnFez04 and PVC are investigated in a series of thermogravimetric and small scale reactor experiments under inert atmosphere at below 1273 K. The reaction mechanisms are discussed· on the .basis of the thermogravimetric data. From the results of reactor experiments, it is shown that the chlorination of Zn in the oxides by Cl in PVC, the vaporization of ZnC12, the reduction of iron oxide to metal Fe by C and H in PVC, and, thereby, the separation of Zn and Fe in the oxides take place simultaneously at the temperature ~= 1200 K.IntroductionSteelmaking dusts are metallurgical wastes consisting mainly of oxides of Zn and Fe with smaller amounts of other heavy metal elements, such as Pb. In the recent investigation, [1] the present authors have investigated the fundamental aspects of a potential pyrometallurgical process· of recycling steel-making dust with polyvinyl chloride (PVC) at temperature T < 1273 K under Ar atmosphere. The performance of a similar process, in which HCl in the combustion gas of PVC is used to chlorinate Zn in the EAF dust under oxidizing atmosphere, has been investigated by Tailoka and Fray [2] with fundamental experiments. Figure 1 shows an example of the potential ·diagram of Zrt-Cl-0 and Fe-Cl-0 systems. In the figure, we can find two regions where ZnCl2(g) can be separated from Fe containing compounds. One is ZnCiz-Fe20 3 coexistence region at higher oxygen and chlorine potentials and the other is ZnCl2-Fe coexistence region at lower oxygen and chlorine potentials. The process adopted by Fray and coworkers is aimed mainly at the performance of Zn/Fe separation in the higher oxygen potential region. In the present study, the lower oxygen potential region is focused on."

Jan 1, 2000

By Mike Dry

While McCabe-Thiele plots are useful for designing single-component solvent extraction systems, not least because of their simplicity, they are less useful for multi-component solvent extraction. This paper presents a relatively simple method, compared to other approaches, for modelling solvent extraction as chemical equilibrium reactions between the various aqueous and organic species. The essence of this approach is how values for the equilibrium constants can be extracted from standard laboratory data. Synergistic solvent extraction of nickel is used to illustrate the method.

By Huimin Lu, Lian Zhou, Panpan Wang

"For the low concentration C02 exhaust gas from coal-fired power plant, steel plant emission trapping and recycle problem, a pressure swing adsorption process was studied, using a porous imidazolate framework materials (ZIFs) as adsorbent, separating carbon dioxide from fuel gas mixture. In the carbon dioxide reduction condition by electrochemical method, using ionic liquids as electrolyte, the oxygen and carbon products could be obtained, including carbon nanotube, nano carbon fiber and amorphous carbon. At last, a new C02 collection, recycling and reuse technology was formed.IntroductionDuring the combustion of fossil fuel in coal-fired power plant or steel plant, large amount of carbon dioxide has continuously emitted into the atmosphere. The phenomenon has resulted in the melt of arctic glacier and the frequent emergence of abnormal climate. How to reduce the emission of carbon dioxide and protect human living environment has become a worldwide challenge. Recently, there are three routes to resolve this problem: The first one is to adjust the energy structure and develop new energy, such as solar, wind, hydrogen; the second one is to improve energy efficiency and avoid waste; the third one is to research capture and sequestration of carbon dioxide (CCS). But many researchers have come to realize that the recovery and utilization of carbon dioxide are more important than the sequestration of it. Because the captured carbon dioxide just buried under the earth maybe cause secondary pollution if carbon dioxide leak out from the adsorbent."

Jan 1, 2013

By Waraporn Piyawit

Grinding sludge from the sintered neodymium-iron-boron (NdFeB) magnets production process was enriched with critical rare earth elements (neodymium, dysprosium and praseodymium), which can be up to 30% in the magnets. The demand of NdFeB magnets are simultaneously growing. Therefore, rare earths recovered from waste residue would reduce the demand of rare earth elements from primary sources. In this study, the feasibility of recycling rare earths through a hydrometallurgical process was investigated. The selective leaching of Nd from grinding sludge can successfully raise the rare earths concentration to 70%. The necessity of an oxidation pretreatment to improve the selectivity between Nd and Fe will be described.

By Jiang Feng, Zhang Libo, Peng Jinhui, Guo Zhanyong, Ju Shaohua, Lei Ting

The basics of microwave drying process of CuCl residue were studied by comparing the dielectric property of the residue with different moisture contents. The dielectric properties were measured by microwave cavity perturbation method. The dielectric constant and dielectric loss factor of the CuCl residue have a linear correlation with the moisture content. With this relationship, we can realize on-line measurement of moisture content of the CuCl residue by dielectric properties. The microwave drying experiments with different thicknesses (1-5cm) of CuCl residue were carried out, and the heating curve of the materials under different microwave powers (250-450W) was made. From these parameters, an optimized operation parameter of microwave roasting technology, the thickness of CuCl residue filter cake to be microwave roasted should be 2cm , was deduced.

Jan 1, 2015

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 Tianzu Yang, Weifeng Liu, Lin Chen, Wei Chen, DUCHAO ZHANG, HUI XIAO

Oxygen-rich side blow bath smelting (OSBS) technology was developed in 2000 based on Vanyukov process. This technology exceeds the traditional pyrometallurgical methods by its great processing capability, high metal recovery and environmental-friendly property. In the past 15 years, OSBS technology extended its application area from lead industry to bismuth, antimony and waste recycling industries, etc. This paper introduces the history and new developments of OSBS technology. The typical industrial applications examples of the OSBS technology in China, including high lead slag reduction, low grade bismuth-lead concentrate smelting and metallurgical waste recycling, are reviewed. Especially, the unique furnace properties and technical parameters are compared. Finally, the potential research directions of OSBS technology are summarized.

Jan 1, 2016

By Gui-fang ZHANG, Zhe SHI, Lei GAO

Secondary V-recycling slag, an industrial waste containing high gallium is being dumped continuously, which causes the loss of gallium. Thus, the alkali fusion process was employed to recover gallium from this slag. The effects factors on extraction of gallium such as roasting temperature, roasting time, alkali fusion agent concentration and CaO concentration were investigated in the paper. The experimental results indicated that excessive roasting temperature and roasting time is unfavorable to the recovery rate of gallium. The appropriate roasting temperature and duration are 1000 and 2 hours, respectively; The appropriate proportioning of Na2CO3: NaOH is 2:1 when the concentration of alkali fusion agent weighs 0.4 times the mass of the slag; In order to remove SiO2 from the leaching liquor, CaO should be used as an additive in the roasting process. The appropriate concentration of CaO should weigh 0.2 times the mass of the slag. Employing these optimal alkali fusion conditions in the roasting process, gallium recovery is above 90%

Jan 1, 2015

By J. D. McCain

Magma&apos;s San Manuel smelter has adopted new operating techniques resulting in 21% increased productivity and 87% reduction in lost time accidents. Reverberatory furnaces were converted to coal firing from expensive natural gas and fuel oil. Slag and matte flow problems and safety were improved by implementing hydraulic slag stopping and matte tapping machines. Coordination of furnaces, converters and acid plant was improved by using a computer-aided converter controller/scheduler function. Manual mudding of converter lips after each collar pull was replaced with a gunning system for coating the mouth castings. One converter punch car was automated using robotic technology. An automatic anode take-off was installed with fewer moving parts and a mechanism for ear twisting one cell contact. Anode copper refining was improved by replacing propane/hydrogen mixtures with high pressure/velocity natural gas tuyeres. Improved converter scheduling increased acid plant production 43% with more autothermal operation time. Six dedicated computers/microprocessors are utilized for automation, data acquisition, process monitoring and on-line air quality information for the Supplementary Control System.

Jan 1, 1983

During electrowinning of nickel chloride, hydrochloric acid was regenerated instead of chlorine in a two membrane cell, by segregating the chloride catholyte with an anion exchange membrane, and the sulphate anolyte with a cation exchange membrane from the middle electrolyte (ampholyte) compartment. Successful operation of such a cell depends on controlling chloride leakage through the cation exchange membrane to the anolyte. Small amounts of chlorine gas could be detected in the oxygen evolved at the anode. In this paper, the chloride. leakage as a function of various types of cation exchange membrane and different composition of the anolyte is reported and discussed. Ag+ was added to the anolyte to eliminate chloride leakage to the anode. The cell voltage, electrode potential and voltage drop over the membrane as a function of current density has also been investigated.

Jan 1, 1996

By Dave Tahija

"Many investigations are being performed with the goal of removing carbon dioxide from the atmosphere and permanently storing it in geologically stable settings. At the same time, carbon dioxide in the form of dissolved carbonate is steadily accumulating in the world's oceans. Both carbon dioxide sequestration and oceanic accumulation are constrained by the aqueous thermodynamics of the carbonate system. These constraints are illustrated using the STABCAL computer model to generate potential-pH and aqueous distribution diagrams of seawater in contact with various pressures of carbon dioxide gas. STABCAL diagrams and titration simulations are also used to model some potentially useful cation-carbonate sequestrationsystems.IntroductionAtmospheric carbon dioxide concentrations have risen dramatically in the past couple of centuries and are rising still, primarily as a result of human activities, especially the burning of fossil fuels. Increased atmospheric carbon dioxide concentrations have been implicated as a main cause of global warming but have other effects as well.Rising levels of atmospheric carbon dioxide result in increased concentrations of dissolved carbonate complexes in water, including the oceans. These dissolved carbonates interact with other dissolved substances, altering overall seawater chemistry, most noticeably causing lowered pH levels.Some of these chemical changes are observed directly, for instance the general drop in oceanic pH, [1], while others can be inferred and predicted using thermodynamic modeling. The chemistry of dissolved carbonate in seawater is not especially intricate, as such chemical systems go, but neither is it simple enough to be worked out on the back of an envelope. Interactions between the several simple carbonate species and all the major dissolved cations in seawater should be considered, as well as the effects of competing anions, especially chloride and sulphate, since they are much more abundant than carbonate in seawater."

Jan 1, 2011

By Jilai Xue, Jun Zhu, Germain Kouma Ndong, Qiaochu Liu, Luxing Feng

"High-temperature oxidation and corrosion behaviors of Ni-Fe-Cr alloy as inert anodes for aluminum electrolysis have been studied in oxygen and molten electrolyte. The oxidation and corrosion scales on the anodes tested were analyzed using XRD and SEM-EDS. The oxidation rate is found to increase with increasing temperature from 700 °C to 950 °C, which can be approximately described by an inverse power rate function. The oxidation scales at 750 °C, 920 °C and 950 °C contain Cr-rich phase along with FeCr204 and (Feo.6Cro4)203. The corrosion extent of Ni-Fe-Cr anodes in electrolyte is dominated by temperature, which can make the scales thickness double from 700 °C to 750 °C or from 920 °C to 950 °C. Cr and Fe in the scales on the anode in electrolysis corrode preferentially into the molten electrolyte, while the nickel oxides could better sustain the corrosive environment in electrolysis. The results can be useful for developing inert anode material for potential application in aluminum electrolysis.IntroductionThe development of an inert anode for aluminum electrolysis has been a long term goal for aluminum industry. The present process for primary aluminum production involves the reduction of alumina with carbon anodes, forming carbon dioxide:"

Jan 1, 2013

By Yoji Imai, Akio Watanabe, Masakazu Mukaida

"To clarify the feasibility of alkoxides and acetylacetonates as precursors for laser CVD of metal oxides, vapors of tantalum or titanium alkoxides and zirconium acetylacetonate were irradiated by KrF excimer laser and deposits were characterized by XRD and XPS measurements. As for tantalum and titanium, non-stoichiometric crystalline oxides grew nearly phototropically, however, zirconium oxides deposited showed only halo-pattern by XRD measurements. Electric conductivity measurements of tantalum oxides implied the improvement of the insulating properties by the addition of activated oxygen to the ambient.IntroductionThere has been renewed increasing attention to the metallic oxide thin films because ofits promising usefulness in many applications, such as high-Tc superconductors and ferroelectric devices. A variety of thin film preparation techniques have been studied such as sputtering, chemical liquid deposition (sol-gel and metalorganic decomposition), pulsed laser deposition and chemical vapor deposition (CVD). Among them, we think CVD is the most promising method because it offers a high controllability of morphology and good step coverage at relatively high growth rate. Preparation of oxide films by CVD can be achieved using a precursor containing metallic element and oxygen containing gas such as N20 at the same time. However, metalorganic (MO) compounds which contain both metallic element and oxygen, directly bonded to metallic element, seems to be more favorable because some of MO has a good properties for CVD such as a rather high vapor pressure, stability in ambient and low toxicity."

Jan 1, 1998

By R. Kola

Since more than 15 years the Waelz process at "Berzelius" in Duisburg has proved suitable for reprocessing the zinc and lead containing dust and .sludge which inevitably occur in making steel in EAF-plants. The produced Waelz-oxide is agglomerated in a hot-briquetting plant and charged to an Imperial Smelting Shaft Furnace to recover the valuable elements in form of metallic zinc and lead. In view of the actual importance of the dumping problems of the EAF wastes a description of the "Berzelius" treatment route is given but also the situation in Western Europe is illustrated. Dust from stainless steel production is successfully treated in the Scan Dust Plasma Process in order to recycle Chromium and Nickel, while the resulting Zinc-Dust is treated via the Waelz-ISF-Route. For treatment of low Zinc-containing dust, sludge and fines from integrated steelworks, pilot scale tests have been carried out successfully in the Circulating Fluid Bed in order to recover metalized iron and .zinc/lead fume. A 30,000 tpy Demonstration Plant is planned?.

Jan 1, 1990

By Glenn Stevens

After 40 years of operation with the original design, Pan Pacific Copper determined it was necessary to rebuild the Saganoseki Flash Smelting Furnace to continue safe operation. The original design employed a rigid steel frame, which, through hearth growth, led to severe distortion of the frame. Contributing to the continued growth of the hearth were thermal cycles that occurred during the government mandated annual shutdowns. Hatch designed a unique sprung bound, pivoting binding frame to maximize crucible size within the existing furnace footprint, while integrating the PPC designed cooling jackets. The bound system maintains tight brick joints, while the new conductive hearth design with integrated bottom cooling produces a protective freeze layer to accommodate higher furnace throughput. Minimization of furnace downtime for the rebuild was achieved through effective construction planning, highly trained contractors, and through an efficient start-up and ramp-up to full production.

By Roderick Guthrie

Gas injection into liquid steel baths is widely practiced, ever since the early days of Bessemer’s pneumatic steelmaking process. What has not been fully appreciated is the critical role of bubble sizes for delivering higher quality commercial steels than is presently possible. This was first proposed by Prof P. Hayes and his research group. Using a full-scale water model of a typical 4-strand Ladle-Tundish-Mold system, we demonstrate the potential advantages of modifying a typical ladle shroud, to generate microbubbles within the water flowing into the tundish. This is possible by taking advantage of high shear rates and turbulence kinetic energy available in that region. These microbubbles enhanced the removal of “micro-inclusions” (hollow glass microspheres) in the 5–50 micron size range, to the upper surface of the tundish. There, they were absorbed into an overlaying “slag” phase. Accompanying CFD studies confirmed that no microbubbles in the size range generated (500–900 μm), pass through the submerged entry nozzles into the moulds.

By Toshio Kurikami, Koichi Yamazaki

"Toho Zinc Co., Ltd Chigirishima Refinery has the production capacity of electrolytic lead for 95000t/y by sintering- blast furnace electrolytic process. Lead raw materials are lead concentrates, spent batteries and dusts that contain lead from other companies, and these are handled by existing smelting process. There are many circulation materials in the process, because the system has been constructed with improving the recovery rate and protecting the environment. This report describes material balance in each process, distribution of the lead and various components, and it examines present state of the processing. In addition, we report the result that we have tried to improve the work environment.IntroductionThe Chigirishima Refinery of the Toho Zinc Co., Ltd. is located in Chigirishima, an island 4km off the coast of Takehara-city, Hiroshima, Japan. The Chigirishima Refinery began lead smelting operations in 1951.The Chigirishima Refinery adopted the sintering-blast furnace-electrolytic process and has an electrolytic lead production capacity of 95,000 tons/year. The existing smelting process handles raw materials from lead concentrates, spent batteries, and lead-bearing dust from other companies. This system was constructed with the intentions of improving material recovery ratios and protecting the environment; therefore, there are many materials recirculating throughout the smelting process. This report describes the material balance in each process and the distribution ciflead and various components, and it examines the present state of processing. In addition, we report the results of our attempts to improve the work environment."

Jan 1, 2000

By M. R. Jolly, J. -C. Gebelin

"A number of different types of so-called ""filters"" are used in the metal casting industries to impart some cleaning effect and flow control on the liquid metal as it passes through them. The filters range from simple planar meshes through extruded channels to reticulated foam structures and they are manufactured from a range of material going from metals to glass or ceramics. It is most common that software packages used in the industry model the filters by a simple pressure drop associated with some area fraction and permeability parameters.Recent experimental work at the IRC in Birmingham [1] has shown that filters of the same type can behave very differently depending upon the casting process in which they are employed. Modelling filter geometries for a range of different casting processes has indicated that the flow of metal and heat losses through the filters are rather complex and should be considered when using filters in the casting processes. This paper will present a number of cases of different types of filters modelled and different processes and indicate some of the sensitivities of the processes to boundary conditions imposed by the process.IntroductionFilters are commonly used in the foundry industry. The real action of the filters on the liquid metal is not really understood. Some filters are claimed to have a chemical action on the liquid metal or to be able to clean the metal by stopping the impurities or oxides that will result in inclusions in the cast part. However, some recent experiment carried out at the University of Birmingham in investment casting and results available on sand casting [2] have shown that the action of filters may be different in these two processes. As the main difference between these two processes is the mould temperature, the hypothesis of a partial solidification of the metal in the filter occurring in the sand casting process during the primary stage of the filling has been advanced, whereas there is little or no solidification in investment casting. In order to verify this hypothesis, and to reach a better understanding of how filters work, a numerical investigation of the flow and heat transfer in filters in both sand and investment casting has started at the University of Birmingham, in the framework of the FOCAST project. The FOCAST project is an EPSRC project aimed to increase the understanding of the investment casting process. Another issue is the way the simulation packages predict the influence of the filters on the metal flow. The filters are most of the time modelled as porous obstacles characterised by a pressure drop calculated from porosity and some surface ratios or proprietary coefficients. This paper will present the preliminary results of this numerical investigation. First, the different models that have been used are presented, followed by the obtained results. A discussion of these results and their perspectives conclude the paper."

Jan 1, 2001