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By Jilai Xue

Oxygen gas bubbles generate on anode during Pb electro-deposition process in PbSiF6-H2SiF6 aqueous solutions at room temperature. Cell voltage varies as the bubbles formed on the anodes surface. The bubble layer on the anode makes a voltage drop that consumes energy in the Pb process, which can be reduced by applying ultrasound on the anode. The effects of ultrasound frequency and anodic current density were investigated with ultrasound on and off, alternatively during the Pb electrode-position process. The removing of the gas bubbles were recorded in association with a drop in the cell voltage. The cell voltage can be lowered by 4% - 6% with ultrasound, which has potential for energy saving in Pb production.

Jan 1, 2010

By Dai Xi

In the present work, the viscosities of molten FenO-MgO-SiO2 and FenO-MgO-CaO-SiO2 semi-synthetic slags for nickel flash smelting were measured in the temperature range from 1473 to 1723K by a rotational viscometer. The ratio of Fe to Si02 was fixed at 1.2, calcium and magnesium oxide contents varied in the range from 2 to 8 mass% and 9 to 12 mass%, respectively. The results showed that silicate anions became smaller by increasing CaO content, which results in a decrease of the viscosity of the slag. In the case of MgO addition the viscosity behavior was complicated. At MgO content below II mass%, the viscosity increased with the increase of MgO at all temperatures tested. However, when the MgO content was above II mass%, the viscosity decreased slightly for FenO-MgO-CaO-SiO2 system. At higher MgO contents, low-viscosity slags can be obtained by adding CaO. At a given composition, .the viscosity decreased with increasing temperature. The higher the temperature, the more MgO can be added before saturation. The effect of Fe3O4 on the viscosity was quite significant. The viscosity of slag increased by 300mPa-s at 1573K when Fe3O4 content varied from 3 to 9 mass%. The viscosity values are presented as the functions of temperature and composition. A comparison between FenO-MgO-SiO2 and FenO-MgO-CaO-SiO2 systems is given in this study.

Jan 1, 2003

By Regina Maria Pinheiro

This work has for objectives to characterize a waste generated in the form of sludge during the treatment of the effluent of a paper making industry and to evaluate the effect of its incorporation in the amount of 10 wt.% on the properties and microstructure of a clayey body used for brick production. For the characterization of the waste the following techniques were used: X-ray diffraction, X-ray fluorescence, differential thermal analysis and termogravimetric analysis. Incorporated bricks were produced in industrial scale before firing at 750°C in a Modified Caieira type furnace. The physical and mechanical properties evaluated were water absorption and compression strength. The microstructure of the fired ceramic was evaluated by optical microscopy. The environmental evaluation was made by solution test and atmospheric emission by monitoring the release of SO2, NOx and particulate material. The results showed that, in agreement with the characteristics of the waste, its recycling into red ceramic can contribute to decrease the consumption of fuel during the firing stage. The properties of the fired ceramic attend the norms. With respect to the environmental aspect, the incorporation of the waste did not impact the environment.

Jan 1, 2009

By Han Yihua, Zhang Caijun, Zhu Liguang, Zhang Qingjun, Wang Shuoming, Wang Yan

An industrial test on 210 t converter-LF-CC production line on high heat input welding shipbuilding structure steel DH36 has been taken in a factory in north China, the effect of adding microalloy elements V and Mg on casting billet microstructure has been researched. It was found that when the composition of V was between 0.03 and 0.05% and the composition of Mg was between 0.002 and 0.005%, a large number of acicular ferrite precipitate in austenitic crystal in as-cast structure and cross into a net structure. The inclusions size which induced intra-granular ferrite are mainly less than 4 lm, especially those between 2 and 3 lm account for 50.80%, in these inclusions the composite inclusions mixed with Mg accounted for more than 60%.

Mar 1, 2017

By Osamu Takeda

A decomposition process for PCBs by using basic molten salts as a reaction field was investigated in order to establish a safe, simple and highly efficient decomposition process for polychlorobiphenyls (PCBs). PCB containing chlorine (e.g. 2, 2?, 4, 4?-tetrachlorobiphenyl) dissolved in n-nonane solution was supplied into basic molten salts (NaOH-Na2CO3 or KOH-K2CO3) maintained at 500-700 ?C together with the carrier gas (N2-21% O2) through an injection tube. The injected PCBs in a bubble are decomposed by the reaction with the molten salts and oxygen during rise in the molten salts. The decomposition efficiency of PCBs increased with increasing temperature and was achieved to be higher than 99.995% in a certain condition. From a series of systematic study, the effectiveness of the decomposition process for PCBs by using molten salts was demonstrated.

Jan 1, 2008

By Phillip B. Messersmith, Emmanuel P. Giannelis

"A versatile in-situ polymerization approach is described for the synthesis of polymerceramic nanocomposites consisting of two-dimensional layers of mica-type silicate (MTS) within polymer matrices. Functionalized, organically modified mica-type silicates (OMTS) were used to promote delamination/dispersion of the host layers and initiate polymerization of organic rrionomer. Epoxy nanocomposites prepared in this manner exhibit substantial modulus reinforcement at low silicate loadings. The water vapor permeability of the poly(?-caprolactone) nanocomposite containing 4.8% silicate by volume was reduced by nearly an order of magnitude compared to pure poly (?-caprolactone).IntroductionPolymer matrix nanocomposites are a relatively new class of materials with dimensions typically in the range of 1-100 nm.1 In general, because of the ultrafine phase dimensions involved, nanocomposites exhibit new and improved properties when compared to their micro- or macrocomposite counterparts. We as well as others are currently investigating the design, synthesis and characterization of polymer-ceramic nanocomposites. Our effort, in particular, has focused on the use of mica-type silicates (MTS) with various thermoplastic and thermosetting matrices.2-5MTS's belong to the general family of 2: 1 layered silicates. Their crystal structure consists of layers of two silica tetrahedral sheets fused to an edge-shared octahedral sheet of either aluminum or magnesium hydroxide. Stacking of the layers leads to a regular van der Waals gap or interlayer.6 Isomorphic substitution within the layers generates negative charges that are counterbalanced by cations residing in the interlayers. Although the natural forms of MTS's usually contain hydrated Na+ or K+ ions, ion exchange reactions with organic cations (e.g. alkylammonium ions) can render the normally hydrophilic MTS's organophilic."

Jan 1, 1994

By V. P. Bystrov

Vanyukov process has been developed and investigated in Russia over the last 25 years. It has been established that various kind of material could be treated in Vanyukov process. The results of the pilot plant trials as well as industrial experience are presented in this paper.

Jan 1, 1993

By John W. Ahlrichs

Microscope, electron microprobe and x-ray diffraction have been used to provide quantitative evaluation of products from the mill, smelter, refinery and other metallurgical processes. Phase compositions and their quantities are necessary for an adequate understanding of the various products obtained throughout an operation and in laboratory testing. By careful evaluation, important information can be gained in improving recoveries and increasing grades at various stages of processing. Four case histories are discussed in this paper. Quantitative microscopic counting techniques are applied to mill products to determine degrees of locking and liberation of the economic minerals. Rapid, but accurate evaluation aids the metallurgist to develop or improve the grinding and flotation circuits. In the smelter, the identification and quantification of the phases are important for predicting reaction mechanisms and kinetic trends. Mineralogic techniques have been applied to conventional smelter products, and to those obtained in laboratory tests for newly developed innovations to smelting. Small, but important, values of gold occurrences in ore are difficult to determine. Evaluation of gold usually requires special separations into various mineral concentrates, followed by assays and mineralogic determinations of the products. Numerous occurrences of solid solution constituents can be treated as by-products, but often they are deleterious to metallurgical treatment. Most solid solution problems can be unraveled by the mineralogist's tools.

Jan 1, 1981

By Brommerm Tracey, Britt Elin Gihleengen, Elsa Olivetti, Hans Ole Riddervold, Randolph Kirchain, Geir Øyen

"Compositional uncertainty in secondary materials and variable processing conditions inhibits secondary material utilization in the production of aluminum alloys. Efforts to implement optimization models that direct batch planning have limited industrial presence due to factors such as the insensitivity of these optimization models to dynamic plant circumstances. This paper describes a chance constrained model formulation that generates lower cost, robust batch plans with significant flexibility towards changes in processing conditions. The principal attribute of the chance constrained formulation is its inherent mitigation of risk by diversifying the batch plan. This paper compares aluminum remelter batch planning using the chance constrained formulation with a traditional deterministic model and a manual batch planner. With the expectation that volatile material prices, restricted scrap material availability, and pressure by consumers and legislation for increased recycled raw material input will continue in the future, batch planning tools that inherently diversify a production portfolio will become increasingly advantageous for industrial aluminum remelters.IntroductionAluminum remelters must develop strategies to incorporate lower cost secondary materials into finished alloys to remain competitive amidst increasingly demanding market and regulatory conditions. Determining the optimal combination of incoming raw materials to produce an alloy that meets compositional specifications presents remelters with a complex problem that has driven the development of computational tools commonly referred to as batch planning or blending algorithms. The ubiquity of the ingredient or raw material blending problem in production has motivated ongoing development of batch planning algorithms since the classic nut-mix problem in the 1950's [1]. The most common model formulation for industrial aluminum remelters are deterministic, linear optimization programs [2]. These blending problems determine the optimal combination of raw materials by minimizing cost subject to constraints around demand, availability, and compositional specification. Despite extensive research and moderate computational requirements, batch planning algorithms are inconsistently used in industry. Insufficient incorporation of the complexity of real world remelting conditions into these models provides an obstacle for their implementation [3]. For example, many batch planning algorithms do not explicitly incorporate the impact of compositional variation of the raw materials on overall batch cost. Additionally, they do not allow for endogenous specification of tolerance to error in batch planning, so provide little flexibility where a batch planner would like to incorporate materials of greater uncertainty. Incomplete accounting for quality variability undervalues secondary materials leading to overly conservative use [ 4, 5]."

Jan 1, 2011

By Tao Li

The development of DP(Dual Phase) steels and TRIP(Transformation Induced Plasticity) steels has received much attention in recent years due to their high strength and simultaneous good ductility, which provides the potential for weight reduce and resource savings on certain components in automobile or other industries. So a controlled rolling process was simulated in the present study by thermomechanical simulator (Gleeble 1500) for producing DP steels on a kind of low carbon steel containing a small amount of Si and Cr. F+M dual phase microstructures have been obtained during continuous cooling processes of a wide cooling rate range from 10°C /s to 60°C /s. The grain size of the dual phase steel developed can be refined to less than 5 m through the mechanism of deformation induced ferrite (DIF) transformation. The ultrafine ferritic grains are equiaxed with high-angle boundary, and the martensite islands of an average size less than 5m disperse uniformly in the ferrite matrix. The ultrafine martensite islands not only inhibit the growth of ultrafine ferritic grains and improve the bonding of F/M interface, but also increase remarkably the strain hardening rate in the processing of the present Dual-Phase steel. As a result, the tensile strength of ultrafine grained Dual-Phase steel reaches higher than 1000 MPa. The result shows that an ultrafine grained Dual-Phase steel of low carbon and low alloy is promised to exhibit desired F+M microstructure by means of this new TMCP process.

Jan 1, 2006

By Masatoshi Ogasawara

Saganoseki smelter & refinery operated two flash smelting furnaces, producing a combined 330,000 metric tons per year (hereinafter mtpy) of copper. In 1996, however, it successfully shifted to a single furnace operation while maintaining production at the same level. Since then, the production capacity has been further increased to the present 470,000 mtpy by technological improvements. Also, in order to reduce the converter load which represents a bottleneck in efforts to increase production, the matte grade was gradually increased and currently runs at 65 to 66% attaining the low copper content in the slag (hereinafter slag loss) of 0.7 to 0.8%. This paper introduces some improvements, recent operation results and thermodynamic analyses.

Jan 1, 2003

By Yuezhen Zhou, Zewei Liu, Dachun Liu, Chongfang Yang, Wenlong Jiang, Fansong Liu

A novel process that the combination of vacuum decomposition and acid leaching was proposed. The influence of distillation times, diameter and thickness of the feeding material on the mass fraction of Molybdenum (Mo) and sulphur (S) in residual was investigated. The influence of leaching temperature, leaching time, concentration of hydrochloric acid solution, and ratio of liquid to solid on leaching rates of Mo and S in acid leaching process was also investigated. Due to the fact that SO2 emission happening in the long process of traditional molybdenum metallurgy could be avoided in this novel method, this combination process was environmentally-friendly. Molybdenum powder was obtained through handling molybdenite concentrate under the optimal condition parameters, and the mass fraction of Mo reached 98.29 wt%. So it's feasible to produce molybdenum powder from molybdenite concentrate by using this new method.

Mar 1, 2017

By M. K. Yelloji Roa

Effect of conditioning with Thiobacillus ferrooxidans on the floatability of sphaierite and galena has been determined in this work. The flotation behavior of the conditioned minerals clearly shows that such bacterial conditioning does produce marked modification of their surfaces. The variables affecting the surface modification and thereby the flotation response of the minerals were found to be cell concentration used for bacterial conditioning, the period of biotreatment and the pulp density. Importantly, while the enhancement in flotation obtained due to sulphuric acid treatment was retarded by biotreatment in the case of galena at all cell concentrations due to electrochemical effects, such decrease occurred in the case of sphalerite only at cell concentration sufficiently high for their attachment to the mineral surface. The effect of bacterial conditioning has significant implications to the differential flotation of sphalerite and galena. Mechanisms responsible for the modification of the surface properties of these sulphides due, to bacterial conditioning are discussed.

Jan 1, 1991

By Edward P. Hagarty

The Hazardous and Solid Waste Amendments (HSWA) of 1984 added Subtitle I to the Resource Conservation and Recovery Act (RCRA), authorizing the Environmental Protection Agency (EPA) to develop and implement a new regulatory program for Underground Storage Tanks (USTs) containing petroleum and other regulated substances. Technical standards required for release detection, prevention, and correction as necessary to protect human health and the environment were promulgated as described in 53 Federal Register 37082 (September 23, 1988). Virginia State Regulations (VR 680- 13-02) and U.S. Army Regulations require that a Corrective Action Plan and a Site Clearance Report be prepared to explain the details of remediation of any contaminated media. Construction of new buildings is proposed in two different areas at Fort Myer in Arlington, Virginia, where USTs containing gasoline, diesel and heating oil were located. Tightness testing performed on these USTs in September 1991 indicated that some of the tanks were leaking. Many of the tanks were removed for permanent closure. Initial Abatement (excavation of contaminated soil) was &ed out immediately. A detailed Site Characterization Study which included Hydropunch", field screening using immunoassay, and pilot test - dual phase (water and soil gas) extraction was conducted. Environmental media were analyzed for volatiles, semi-volatiles and metals. A detailed risk analysis (RA) was performed to determine risk-based clean up levels for benzene, toluene, ethylbenzene, xylenes (BTEX); polycyclic aromatic hydrocarbons (PAHs); and methyl-tertiary butyl ether (MTBE). The RA also discussed the presence of lead in the soil. Before constructing any buildings in these contaminated areas, remediation must be conducted in accordance with the State, Federal and other applicable regulations. The remedial alternatives evaluated included Vapor Enhanced Groundwater Extraction, Soil Vacuum Extraction, Soil Washing, Soil Steaming, Active and Passive Ventilation SolidificationlStabilization, Vapor Barrier Construction, and Excavation with Off-site Disposal. This paper discusses: (a) delineation of soil contamination @) risk analysis (c) evaluation of remedial alternatives and selection of the most appropriate technology and (d) consideration of various regulatory issues.

Jan 1, 1994

By Giuseppe Granata

An innovative process using titanium tetrachloride (TiCl4) gas as reactant has shown successfully to obtain titanium through electro-winning of TiCl2 formed in-situ on titanium cathode. The process involves a continuous feed of TiCl4 gas reacting onto a titanium cathode immersed in a molten salt (NaCl-KCl), whereby in-situ formation of titanium dichloride (TiCl2) through a disproportion reaction. Simultaneously, the TiCl2, thus in-situ formed in the molten salt media, has been reacted into chlorine gas and titanium, the latest electrodeposited on the titanium cathode by electrowinning. The reaction kinetic of this innovative process was investigated in terms of TiCl2 in-situ formation rate and galvanostatic electrodeposition rate, where, in particular, the effect of operating variables such as TiCl4 partial pressure and flow rate, as well as temperature and galvanic potential applied was investigated.

Jan 1, 2014

By Tapio Ahokainen

Commercial modeling software and increasingly efficient computers enable today computational fluid dynamics (CFD) to be used as a tool for a more comprehensive understanding of the flash smelting and flash converting processes. CFD modeling can be used for design purposes in many technological areas, but some relevant physical and chemical phenomena are still missing in the commercial CFD solver packages. Therefore, Outokumpu has developed several subroutines for solvers to describe analytically the phenomena in the flash smelting environment. CFD sub-models of the copper concentrate and matte combustion, the particle-particle-wall interactions and for more accurate radiation properties of the gas-particle suspension are needed to ensure reliability of numerical simulations on the flash smelting and converting vessels. Several basic combustion phenomena can be modeled with a number of commercial solver packages, but own models for combustion must be included in the case of sulfides as the feed. Mathematical models for copper concentrate and solid matte combustion have been developed during the last decade. They calculate compositions of the particles and temperature, based on extensive experimental research work in laboratory scale furnaces with validated kinetic parameters and temperature measurements of reacting particles. Inside and near the concentrate burner, the standard particle tracking methods do not include the particle-particle interactions and the particle-wall interaction is too much simplified to describe properly the particle collisions with the distribution cone. Therefore, additional models for the particle-particle as well as particle-wall interactions have been written and implemented. For thermal radiation, models for the emissivity of a gas mixture and for calculating the particle absorption and scattering coefficients have been developed and tested. In addition, the advanced radiation model can be used i.e. in the enhanced simulation of off-gas cooling in the heat recovery boiler area of the flash smelter.

Jan 1, 2006

By M. Nilmani, J. Sofra

The transverse distributions of the solids discharge velocity and mass flux at the discharge end of vertical and inclined lances were measured in order to detennine the transverse distributions of the axial momentum flux, which is a dominant factor influencing the penetration behaviour of particles into melts during submerged injection. The effects of gas velocity (10 - 30 m/s), solids loading (5 - 10), lance length (0.15 - 1.0 m), lance inclination (vertical downward - horizontal) and particle density (2500 - 8900 kg/m3 ) were investigated, while the lance diameter and particle size were fixed at 10 mm and 220 µm respectively. The particle velocities and mass fluxes were measured by image analysis of particles illuminated in a laser-generated light sheet aligned vertically through the axis of the lance at the discharge point. The particle discharge velocity profiles for vertical downward flows were synunetrical about the centre-line of the lance, with the maximum velocities occurring at the centre-line. The velocities increased with increasing gas velocity, increasing lance length and decreasing particle density in accordance with previous observations. The transverse mass flux profiles were also synunetrical for vertical downward flows, however at the lower gas velocities the peaks in the profiles were displaced from the centre-line of the lance by a fractional diameter of about 0.15. The particle discharge velocity profiles become increasingly asynunetric as the lance orientation was changed from vertical to horizontal, with higher particle velocities present near the top wall of the lance. The mass flux profile also became asyrrunetric as the horizontal orientation was approached, however in this case, the profile became biased towards the bottom of the lance. The effect was much more pronounced for a gas velocity of 10 m/s than for 30 m/s, showing the relatively stronger gravitational influence as the velocity was reduced.

Jan 1, 1996

By Rodney Hundermark, July Ndlovu, Lloyd Nelson, Phillimon Mukumbe, Paul van Manen, Whitey Seyanund, Bart Pieterse, Bertus de Villiers, Diale Mokwena

The 2003 redoubling in power to 68MW on the Polokwane Smelter furnace represented a significant intensification in platinum group metal (PGM) smelting. Combined with onerous ‘green’ PGM concentrate smelting requirements, this yielded conditions unusually corrosive to copper coolers and refractories. This presented unexpected operational and design challenges to reliable crucible operation and maintenance. Combined with specific operational control intervention, development of protective coatings has led to the life of water-cooled copper components improving from 9 to 40 months. The furnace matte endwall was extended in 2010 to address accelerated wear of refractories and the potential risk for contact of copper components by superheated matte. An 18 month planned endwall rebuild cycle has been demonstrated (versus catastrophic failure within 9 months). Finally, benefits including lower energy consumption, improved metal recoveries and higher productivity resulting from operational and in-house design developments will be described, that justify “Celebrating the Mega-scale” in PGM smelting.

Jan 1, 2014

By Cheng Yan, Yugang Li, Qian Wang, Lizhi Zhang

In continuous casting process, mold powder has lots of metallurgical effects, such as covering the molten steel to prevent liquid steel from oxidation by air, preserving heat for top layer liquid steel, lubricating initial shell and so on. However, mold powder also can deteriorate the quality of final products obviously after the entrapment of mold powder in steel. In the present work, based on the similarity theory the effect of technological parameters on mold powder entrainment was investigated by water model. Experiment was carried out in the water mold using oil and water to simulate slag and steel, respectively. The results showed that increasing casting speed increased the water-oil interfacial fluctuation and entrainment frequency; viscosity of oil also had a great impact on the interface fluctuation and entrainment; water-oil interfacial tension effect the entrainment while not changing the interfacial fluctuation; submergence depth had little impact on entrainment and interfacial fluctuation.

Jan 1, 2015

By Wei Gao, Qing-cai Liu, Cun-fang Lu, Huimin Zheng, Jian Yang, Chun-ling Yao

"Mercury in flue gas of coal-fired plants was concerned as another serious pollution when sulfur dioxide pollution was controlled now. The adsorbent made from fly ash by thermal precipitation sulfur to remove mercury in fuel gas from coal combustion plant, SEM, BET, TGA and other measurement methods were used to characterize the effect on surface morphology, sulfur distribution and specific surface. High temperature deposition furnace was applied to increase sulfur content in fly ash based adsorbents produced in lab. The study found that sulfur attached to the adsorbent surface, mesopore and microporous structure, increasing its sulfur content of adsorbent. Sulfur was filled in interspace as small molecule S2, S5, increased their surface area and enhanced their adsorption capacity. The specific surface area increased by thermal precipitation sulfur, and specific surface area which increased with increasing temperature.1. IntroductionThe mercury emission caused by human activity has accounted for 10%-30% of total mercury emission all over the world[11, and the emission from coal-fired power plant have a huge proportion of these emission caused by human activity. Active carbon microstructure and surface morphology play an important role in its adsorption capability, which offers the potential for controlling environmental pollutant, such as sewage, fuel gas, atmosphere and et al [2,31, because it is a material with high specific surface area that long been considered as an excellent adsorbent. At present, include activated carbon, fly ash, calcium-based sorbents and other novel adsorbents. The adsorption capacity and production cost were very important in the process of mercury removal by adsorbents, so the mercury removal has focus on developing adsorbents of highly-efficient. In particular, the waste of metallurgical from coal combustion and the others have a significant advantage about the cost, and they have the highly-efficient in mercury removal after modified to enhance their adsorption capacity, such as fly ash of coal-fired. Apart from specific surface area, element content, pore structure, and surface morphology of activated carbon have great effect on its adsorption ability. Compared to adsorbents without modification, active carbon impregnated with other elements, such as chlorine, sulfur, bromine and et al. had more excellent characteristics to remove specific pollutants."

Jan 1, 2011