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By Charles A. Sorrell

Two red muds, two fly ashes, and several aluminosilicate minerals were subjected to direct treatment with concentrated H2SO4 at temperatures of 175°C and below. X-ray analysis showed that virtually all the sulfate reaction products remained in the solid residue because of their low solubilities in x SO Substantial portions of the Al2O3 Fe2O3TiO2, Na2O, and K2O components of the materials reacted to form water soluble sulfates, which were then removed by H2O leaching at 55°C. The solid residue after water leaching consisted largely of amorphous silica and, in lime bearing compounds, CaSO4, The reaction and leaching processes were effective in removing all or nearly all the Al2O3. Fe2O3, TiO2, Na2O, and in lime components in the fly ashes, red muds, china clay, bentonites, the nephelioe fraction of nepheline syenite, and a plaster insulating brick composed of anorthite and mullite. Reaction with potassium feldspar and petalite took place, with formation of alkali aluminum sulfates, but the reaction rates and yields were extremely low. Potassium feldspar can be heated with Na2O and x O in air at 700°C for 24 hours, or with CaO at 1000°C for 24 hours, after which the reaction product kaliophilite, nepheline, and leucite-like phases, prove to be very susceptible to H2SO4, reaction and H2O leaching, providing yields near 100% of the Al2O2 content. An alternative method of H SO treatment consists of heating the sample in a silica tube and passing H2SO4 vapor over it. Preliminary results indicate that this method can be effective in enhancing the kinetics of reaction with the Al O component of potassium feldspar and offer the possibility that formation of Al2 (SO ) Fe2(SO4)3 and TiOSO4 can be accomplished selectively by taking advantage of the fact that the upper stability limits of the respective sulfates in the presence of H2SO4 vapor will be different.

Jan 1, 1982

By K. Krishnapisharody

The phenomenon of slag droplet formation under the action of gas-stirring in steel ladles has been analyzed with experiments conducted in a thin-slice room-temperature model using water and mineral oils as the working fluids. Visual and video investigations have been performed on the interface behaviour along with measurements of liquid velocities in both phases, using the Particle Image Velocimetry (PIV) technique. The measured velocity data and observations on the interface break-up establish that the droplet formation results primarily from an instability mechanism at the interface.

Jan 1, 2008

By Federico Chavez

The process for recovering lead from battery residues used in several Mexican Plants include lead blast furnace and rotary furnaces. The formers are basically fed with recycled batteries together with the necessary additives to produce metallic lead. One of the by-products generated in the blast furnace is a dust mainly formed by lead sulfide. The rotary furnace is used to recover lead .from lead batteries, dross from the refining-alloying process and the leady fines produced in the blast furnace. This paper describes thennodynamic analysis made to the rotary furnace process to understand the effect that each component of the system has upon the lead recovery. In order to enhance the process, the influence of iron chips composition and excess coke on slag viscosity is discussed. A computer optimization program . has been developed to design the furnace charge based on material and energy balances, .together with the thennodynamic equilibrium calculation.

Jan 1, 1995

By F. J. Tavera

The column flotation technology, at first developed for application in mineral dressing, has received special attention in processing of non-mineral dispersions as a result of its low cost, high efficiency and relatively simple operation. This paper presents the results from the operation of a laboratory flotation column for the separation of vegetable oil and soap from aqueous industrial effluents, The flotation system was operated under continuous countercurrent conditions without and with additions of a cationic collector. The experiments show that it is possible to separate about 80% of the organic phase in a rougher flotation stage. These results suggest that the recovery of the organic phase is highly dependant on the dispersion characteristics (i.e. bubble size, gas holdup and bubble surface area flux) and the existing an optimum bubble size from which either smaller or larger, the recovery of the organic decreases.

Jan 1, 2003

By Jintao Gao, Zhancheng Guo, Chong Li

A new approach to enrich MFe and RO phase from the converter slag by super gravity was investigated. The samples obtained by the gravity coefficient G=600 and cooling rate V=5K/min from 1623K to 1373K appeared significant stratification and the MFe gathered at the bottom of sample. With the help of metallographic microscopy and X-ray diffraction, it is found that large quantity of white RO phase gathered at the lower part of the sample as the concentrate, with volume fraction appearing gradient distribution along the direction of super gravity, while the upper part was mainly composed of dicalcium silicate as the tailing. The mass fractions of the FeO, MgO and MnO in the concentrate are up to 40.46%, 6.9% and 3.91%, while that in the tailing are just 11.65%, 2.15% and 1.55%. The recovery ratios of FeO, MgO and MnO in the concentrate are 60.35%, 58.45% and 72.24%, respectively.

Jan 1, 2016

By Xu Zhang, Xuewei Lv, Guibao Qiu

Slag foaming phenomenon is of vital importance to the mass and energy transfer in metallurgical processes. A considerable extensively studies carried out via out-gas in the past cannot simulate well the foaming phenomenon formed in the blast furnace where high TiO2 iron ore is used. A gas reaction was designed in the water-glycerol system to simulate the inner-gas system. This study investigated the influences of solution viscosity, particle concentration and particle size on foaming caused by endogenetic gas. The results show that the foaming height decreases with the increase of solution viscosity, which means reduced foaming ability, more difficult foaming elimination process and prolonged time for natural defoaming. With increasing the solid particle content, the foam height presents a trend which increases firstly and then decreases. Under a certain solid particle content, foaming height decreases with the increase of solid particle size, indicating a weak foaming ability.

Jan 1, 2015

By Yuanbo Zhang, Zhixiong You, FENG ZHOU, Guanghui Li, Zhengwei Yu, Zhiwei Peng

Reduction disintegration of sinter significantly affects the coke consumption and productivity of blast furnace smelting. As we know, the reduction disintegration index (RDI+3.15) of sinter obtained from titanomagnetite concentrate is relatively worse than those from ordinary iron ores. In this study, the effect of sintering parameters, mainly involving coke breeze dosage and basicity on sintering indexes was investigated using titanomagnetite concentrate as raw material in an experimental-scale pot. Subsequently, RDI+3.15 of the sinter was detected according to the Chinese standard of GB/T13242-91. The results show that RDI+3.15 rises with the increase of coke breeze dosage, while it decreases with increasing basicity from 0.5 to 2.0 and then increases in the basicity range of 2.0-3.0. Finally, the microstructure of sinter before and after reduction was studied. And the mechanism of reduction disintegration was preliminary revealed by analyzing the morphologies and distributions of minerals in the sinter.

Jan 1, 2015

By V. D. Tathavadkar

Natural chromite mineral is a solid solution of spinet end members namely: chromite (FeCr2O4), hercynite (FeA1204), magnetite (Fe3O4), magnesio-chromite (MgCr2O4), (MgA12O4), and magnesio-ferrite (MgFe2O4). A phase transformation in chromite minerals occurs in oxidising conditions during the soda-ash roasting reaction. This phase transformation plays an important role in improving the extraction efficiency of Cr3+ from mineral phase. The extraction efficiency of chromium (Cr3+) from chromite to a water¬soluble sodium chromate (Cr6+) salt depends upon the decomposition kinetics of the spinet phase. An investigation of the phase changes in chromite ores in the absence of sodium carbonate was carried out in air, argon, and in argon +5 % hydrogen gas mixture. The thermodynamics of phase transformation reaction in chromite solid solution phase is discussed using the solution model proposed by Sack and Ghiorso [1]. The microstructural changes and the changes in elemental compositions of different phases were examined by SEM and electron probe microanalysis (EPMA) respectively. The experimental results indicate that the solid solution spinet phase in chromite mineral undergoes spinodal decomposition under the influence of oxygen partial pressure and temperatures. The structure of phases formed and their morphologies suggest that the phase decomposition may be similar to those observed by Burkert et. a]. 121, although the scale of phase separation in chromite appears to be strongly dependent on oxygen partial pressure.

Jan 1, 2001

By Graham J. C. Carpenter, Marc Charest, Jason Lo

"The method of producing magnesium-based composites with silicon carbide (SiC) particulates embedded in the matrix of magnesium AZ9I D alloy by the squeeze-casting technique are described. This method involves the fabrication of a SiC particulate preform and the subsequent squeezing of molten magnesium into the preform. In this study, alumina, aluminum phosphate and a proprietary binder were used for the fabrication of SiC particulate preforms. The procedures employed in the fabrication of SiC! AZ9ID composites are presented, together with the results of characterization of the composites using optical and transmission electron microscopy. Special attention is given to the reaction products in the bulk alloy and at the interfaces between SiC particles and the AZ9ID matrix alloy.1. IntroductionInterfacial, microstructural and metallurgical characteristics play an important role in determining the mechanical properties of a composite. In theory, reinforcing magnesium with SiC particulates should provide an improvement in strength and modulus of the composite over the unreinforced counterpart. However, many factors resulting from the fabrication process can cause degradation rather than improvements to the mechanical properties. In particular, the interfacial characteristics are known to critically influence the properties of composites [1]. Before evaluating the mechanical properties of a composite, it is always useful to examine the microstructure, which is closely related to the mechanical behavior. This helps to reduce the labor-intensive steps of sample preparation for mechanical property evaluation, which can be particularly difficult as a result of the high hardness of composite materials, as well as providing a wealth of information on the microstructural and interfacial characteristics, particularly the reaction products caused by processing. This information is also pertinent in understanding the factors governing the mechanical properties of the composites.There are many factors which determine the nature of the interfacial characteristics of a SiClMg composites. Qualitative estimations of the interfacial bonding have been performed based on thermodynamics, electronic and electrostatic concepts. In addition, the kinetic conditions during the fabrication play an important role. From an interfacial energy standpoint, the driving force for the formation of a metal/ceramic interface is the decrease in free energy that occurs when intimate contact is established between metal and ceramic surfaces. The simple representation of the energy change per unit area of interface formed (~G) is given by Dupre equation [2]:"

Jan 1, 1996

By Corby G. Anderson

In the majority of industrial operations recovering gold and silver by hydrometallurgical means, cyanide is the predominant lixiviant. However, as an economic alternative, production of massive quantifies of silver chloride was done on an industrial scale in the nitrous-sulfuric acid pressure leaching of a refractory precious metals concentrate. This proven process required no cyanide. Thus, because of the large volumes encountered during day-to-day plant operation, the need for efficient and low cost methods of silver chloride precipitation, reduction and materials handling was mandatory. As such, this paper covers the evolution of plant scale precipitation, filtration, washing, reduction and control of silver chloride processing. As well, an in-depth description of the unique leaching system is included.

Jan 1, 1998

By W. B. Carter, A. T. Hunt, G. W. Book

"Combustion Chemical Vapor Deposition (CCVDSM ), an open air, flame assisted CVD process, is under development. The CCVD process produces non-line-of-sight, epitaxial deposition. Materials deposited include YBa2Cu3Ox' Y2BaCuOx, BaTiO3, Y2FesOI2, ZrO2, yttria stabilized ZrO2 (YSZ), partially (yttria) stabilized ZrO2 (PSZ), and amorphous silica. Two modifications of the CCVD process are being studied. Liquid fuel CCVD deposition, involves the combustion of an organic solvent that contains dissolved reagents carrying the desired coating cations. Gaseous fuel CCVD deposition uses a flammable gas as fuel. A non-flammable solution containing dissolved reagents is either aspirated into the flame or mixed with the fuel gas as an aerosol prior to its combustion. Substrates to be coated are held near the flames' ends.IntroductionThin films and coatings can be deposited using a wide variety of techniques including chemical vapor deposition (CVD). CVD is ""a materials synthesis process whereby constituents of the vapor phase react chemically near or on a substrate surface to form a solid product.""lIn conventional CVD processing, gases carrying coating constituents flow into a reaction vessel where deposition occurs onto a heated substrate. The deposition process is often conducted at reduced pressure. Both cold and hot wall reaction chambers are used. Heat can be provided by a resistance furnace, rf induction, or high-intensity radiation lamps. Plasma, microwave, photo, laser, RF, and electron-enhanced CVD processes have been developed. The necessity of using a reaction vessel limits the substrate size and affects coating economics. Although most CVD depositions are performed as batch processes, continuous deposition can be accomplished with the use of appropriate hardware.The chemical vapor deposition of thin, dense oxide films has been accomplished in the open atmosphere with a flame assisted process. The process is called combustion chemical vapor deposition (CCVDSM).2 Two modifications of the CCVD process have been developed. The liquid fuel CCVD process involves the combustion of an organic solvent in which reagents (containing the coating cations) are dissolved. The gaseous fuel CCVD process uses a flammable gas as fuel. In this modification, a non-flammable solution containing dissolved reagents is either aspirated into the flame or mixed with the fuel gas as an aerosol of small droplets prior to its combustion. Substrates to be coated are held near the flames' ends."

Jan 1, 1994

By D. Lambert

Process modeling for large deformation metal forming processes has been developed into a very successful tool in commercial applications during the last two decades. DEFOR.MTM is a well-known metal forming process simulation program used by many industrial and research institutions. Recent developments include the ability to model multiple deforming body behavior during multi-pass pack rolling and microstructure prediction during multi-pass shape rolling. This paper summarizes how DEFOR.MTM can be applied to a number of rolling processes and briefly describes preliminary work carried out using the ALE technique. Keywords: Simulation, Rolling, Pack, Shape, Microstructure, FEM, ALE, Tantalum

Jan 1, 2003

By Yuanbo Zhang, Yongbin Yang, Guanghui Li, Zhengwei Yu, Yufeng Guo, Tao Jiang, Xiaohui Fan, Youming Hu

"Composite agglomeration process (CAP), as an innovative method for preparing blast furnace burden, was developed and has been put into operation in China. CAP is different from traditional agglomeration processes of iron-bearing materials involving sintering and pelletizing. Compared to the traditional agglomeration processes, CAP is characterized by several strengths such as permission of diverse iron-bearing materials in production, obvious improvement of permeability in the feed bed, decreasing the fuel consumption and remarkably increasing the productivity of sintering machine. Furthermore, the use of the composite agglomerates prepared with CAP is capable of obviating the negative effects caused by the differences in quality of sinter and pellets on the operation of blast furnaces. This paper mainly presents an overview of the principle and applications of CAP.Development Background and Principle of CAPhe traditional agglomeration processes including sintering and pelletizing have been the two predominant methods for preparing ironmaking burden from iron-bearing materials. Sintering is a way for agglomeration by heating the coarser fine ores (general granularity 0~10mm). The mechanical strength of irregular porous sinter is obtained by the solidification of molten phase at high temperature process. It has been shown that the production of high basicity sinter (R=1.8~2.2) is characterized by low energy consumption and high efficiency compared to low basicity sintering. Meantime, the finished high basicity sinter is characterized by good mechanical strength and metallurgical performance. Pelletizing is another way for agglomeration by firing wet green pellets, which are balled from the fine grained iron ores or concentrates. Based on the differences of chemical compositions, the finished pellets can be divided into acidic oxidized pellets, fluxed pellets, magnesium-bearing pellets, and so on. The acidic oxidized pellets are the dominant products of modern pelletizing."

Jan 1, 2012

By James W. Evans, Dong Xu, Jr. Jones

A physical (water) model based on particle image velocimetry (PIV) has been constructed at UC Berkeley. The PIV technique enables the use of water modeling to quantitatively characterize the fluid flow behavior in the mold during the continuous casting of steel, in a whole field sense, i.e., section by section. A method to obtain e\e time-averagevelocity (TA V) vector maps was developed by averaging 40 instant aneous vectc -r plots revealing the time average features of the flow. Another benefit of TAV vector maps is the ability to compare with present mathematical models, which are mostly based on the time-average technique. Bifurcated submerged entry nozzles (SEN) with ports inclined at various angles to the horizontal were used in the modeling to study their effects on the flow inside the caster. Argon was also introduced into the model to simulate the influence of argon injection on the metal delivery from the tundish into the caster. The bubble sizes and distribution (in specific sections) of argon were characterized, at the same time, by the imaging system of the PIV. This will allow for validation of current mathematical models that were developed to simulate argon injection in casters. Comparison with results calculated by the commercial finite element package FIDAP is also presented.

Jan 1, 1998

By Kenneth L. Driggs

The Environmental Protection Agency's Clean Air Act? of 1970 provided the driving force for the current Magma Smelter configuration. The historical and technical perspectives of those process developments are reviewed?. Innovations in procedures and equipment have allowed compliance with the requirements of the regulating authorities?. The wet scrubbing of converter gasses and the monitoring of converter operations by a controlling foreman are two of the major contributors? to these successes. The Clean Air Act Amendments of 1990 have posed many new concerns? for all U.S. industry, including the few (seven) primary copper smelters remaining. Future concerns include tightening the sulfur dioxide ambient ?Standard from the current three-hour averaging period to one hour.

Jan 1, 1992

By Jinjing Dua, Jun Zhua, Kuiren Liub, Bin Wang, Xiaolei Wua

V-Ti-Fe as hydrogen storage alloy was prepared by reducing metal oxides with a metallothermic reduction method. The deoxidation process of the V-Ti-Fe alloy was performed by electro-deoxidation and vacuum induction melting method, respectively. The results showed that the content of oxygen impurity can be controlled at about 0.2wt% after electrolyzing for 240min. Both the maximum values of hydrogen absorption capacity and the effective hydrogen desorption capacity are 2.65wt% and 1.01wt%, respectively. The deoxidization effect of vacuum induction melting process is more remarkable, with Ce as the reducing agent. It is found that Ce addition is beneficial for reducing the componential segregation, promoting the hydrogen absorption activation of V-Ti-Fe alloy. When m(Ce)/m(alloy) is up to 5%, the oxygen content has been reduced to 0.05wt% and the maximum hydrogen absorption capacity and the effective hydrogen desorption capacity are up to 3.36wt% and 1.85wt%, respectively.

Jan 1, 2015

By Kumar M. Lyer

Residence time distribution (RTD) of light and heavy liquids in a pyrometallurgical channel reactor was mathematically modeled by representing the reactor as a combination of ideal reactors. Cold model studies simulated the counter-current flow of slag and matte (or metal) with high-strength bottom gas injection. The experimental variables include flow rates, heights, density and viscosity of the two liquids; gas flow rate; injector diameter; and distance between injectors. The experiments covered a wide range, of the appropriate dimensionless parameter, including conditions in ferrous and nonferrous extractive metallurgy. Dispersion modeling studies were also carried out to determine the degree of backmixing. Results indicate that the degree of backmixing in the channel reactor for various operating conditions corresponds to that for 3-20 perfectly mixed reactors in series.

Jan 1, 1993

By C. J. McKee

A gold-silver-lead-zinc deposit at Montana Tunnels, Jefferson County, Montana is located in a diatreme of middle Eocene age (45 to 50 m.y.). Sulfide minerals within the diatreme occur as disseminations, veinlets, and locally as breccia matrix. Principal sulfide minerals are pyrite, sphalerite, and galena. The diatreme is a matrix-rich quartz latitic breccia with a fine grained rather soft matrix and heterolithic clasts. The ore deposit contains approximately 50 million tons of ore at a grade of 0.025 oz/ton Au, 0.5 oz/ton Ag, 0.25 % Pb, and 0.65 % Zn. Mining is by open pit methods. The original process flowsheet included flotation and cyanide leaching. Problems with the leaching circuit led to a change to the straight flotation process which is presently in use. To maintain a reason-ably uniform feed material, blending of ore is required for grades of four metals as well as for ore hardness and oxidation.

Jan 1, 1988

By Ronald Erdmann

Today the BOF filter dusts and sludges are mainly dumped due to their zinc contents. By typically ranging from 2 to 5 % they prevent the filter dusts and sludges from beeing recycled via the blast furnace route. Based on the different discharge kinetics of Iron and zinc during the main blowing period In a bottom stirred BOF a simple and efficient system for recovery allow zinc fractions has been developed. The obtained material Is suitable for recycling without nsc of shell formation In the blast furnace. Different subsequent development steps have been performed. By starling with a very simple lime dependent model the sludge from the BOF off gas cleaning system was collected in two different sludge channel systems. This model based an the fact that most of the scrap based zinc Is discharged from the melt within the first eight to ten minutes of the BOF process. To Improve the system a spectroscope zinc sensor was Installed at the hot section of the off gas cleaning system to get more reliable informations on the actual zinc concentation of the BOF dust. By use of the system up to 50 % of the BOF sludge can be recycled.

Jan 1, 1995

By S. K. Utimurd, D. C. R. Espinosa, J. A. S. Tenório

"Waste Electrical and Electronic Equipment (WEEE) has become an environmental issue due to technological advance and waste plastic is one of the main polluters. The excessive discard of these plastics result in a difficult to dispose it to landfill and need further separation with technique in order to produce high added value plastics. There are many kinds of plastics in extensive use at the present time and the co=on are the acrylonitrile-butadiene-styrene (ABS) and high impact polystyrene (HIPS) used in the production of electric appliances. These plastics are difficult to separate because they have similar densities. Flotation of plastics is one possible separation technique and using selective wetting agents. The separation may be possible given close control at particle size and the concentration of the reagent. The process was able to produce a concentrate of HIPS with at least of 93% purity and a concentrate of ABS with 99% purity.IntroductionThe current situation of municipal solid waste (MSW) management especially in emerging economies like Brazil, the growing population and economic activity will result in a significant increase in the generation of waste in the coming decades. It is worthwhile to review and update the sources, amounts and recovery technologies of specific materials from waste, particularly from municipal solid waste (MSW).The growing impact of the current waste management practices stresses the need for a change in how waste is handled. The 2012 survey and the Brazilian Association of Public Cleaning and Special Waste Disposal Companies (ABRELPE) reports the generation of 62 Mt urban MSW in that year, which is an increase of 13% compared to 2011. It has been reported that in Brazil about 90.17% of the generated MSW is currently collected, which indicates an increase in the coverage of collection services compared to 2011 [ l]."

Jan 1, 2014