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By Merete Tangstad, Gabriella Tranell, Jeff Kline

"Raman spectroscopy as an instrumental technique for the determination of silicate structure is widely accepted. This method was utilized for analysis of structural modifications associated with the addition of network modifying species. Silicate melts are described by the extent of oxygen bridging. Therefore, understanding the effect different oxides have on modifying the silicate structure will provide valuable information regarding the removal of boron from silicon in slag refining processes. Samples ranging from CaO/SiO2 = 0.56-1.2 were evaluated with and without varying concentrations of B2O3. The addition of CaO to SiO2 revealed Q2 species constitute 45% of the Qn species and addition of B2O3 to the high concentration CaO system results in an increase in Q2 and a decrease in Q0 . The disappearance of the Raman band associated to the three-member ring in the low concentrated CaO system indicates boron addition and destruction of the ring.IntroductionExtensive studies on the structure of silicate systems have been performed using Raman spectroscopy with consensus on the Raman shift associated with different bridging oxygen units [1]. Most of these studies are motivated by the lack of a fundamental understanding of the processes involved in petrology. Due to this, an opportunity exists to build on the knowledge obtained from these studies and conduct more research on slag structures relevant to industrial applications, as these systems are often compositionally similar to magmatic melts. Raman spectroscopic studies of industrial slags will provide insight into the possible structural modifications necessary to enhance removal of impurity species from the metal phase to the slag phase."

Jan 1, 2012

By R. Lanza, M. Hytros, N. Saka, I. Jureidini, J. H. Chun, D. Kim

"A novel method for delineating the solidification front in metal casting has been developed using the attenuation phenomenon of electromagnetic radiation (y-rays or x-rays) and computed tomography (CT). The densities of the liquid and solid phases that exist during metal casting may differ anywhere from 4 to 12 % depending on the metal. As in the medical imaging field, CT provides an excellent means of mapping this density variation in a solidifying casting into two-or three-dimensional images.In an effort to develop an industrial-scale sensor, laboratory-scale experiments have been conducted using a cobalt-60 (Co60) radioisotope and a sodium-iodide (Nal) scintillation detector. The CT image reconstruction was performed on a crucible containing pure tin in a two-phase state. Although the spatial resolution and data acquisition speed were not optimum, the CT images clearly differentiate the liquid and solid phases of the tin in the crucible. To maximize resolution and minimize data acquisition time, a linear accelerator (linac)-based CT sensor is being developed and tested for application in the continuous casting of steel and aluminum alloys.IntroductionIn all casting processes, the quality of a finished product and its production rate depend upon the shape and movement of the solidification front. From a quality perspective, it is well documented that solidification kinetics (heat and mass transfer, fluid flow, microstructure evolution) greatly influence the final properties of castings [l,2,3]. Product shortcomings, such as surface defects, cracks, macro-and microsegregation, and inclusions are directly controlled by the solidification process. By understanding the role the solidification front plays in the casting process, product quality may be dramatically increased through the reduction of defects."

Jan 1, 1997

By S. Suzuki, Y. Maeda, N. Wakamatsu

"A new pyrometallugical technology, named KLS process, has been developed by Dowa Mining at its Kosaka Smelter to smelt various kinds of lead raw materials.The process consists of clearly separated two reaction steps, smelting and reduction. For this purpose, respective stationary furnaces are installed which are connected by a slag launder.Dry raw materials, together with pulverized coal and oxygen-enriched air, are injected through a lance pipe into the molten slag in the first furnace. It is kept under a high oxygen potential to remove sulfur completely. Resultant PbO rich slag overflows to the second furnace where pulverized coal and insufficient air are also injected through a lance pipe to reduce PbO to lead bullion and to compensate for thermal deficit. The entire operation is carried out continuously. The process development started back in 1981. In late 1986, a pilot plant with a capacity of 3.5t/H was constructed.Already nearly 20,000 tons of raw materials, mostly lead sulfate mixtures have been smelted successfully.IntroductionFor a long time, main raw materials for lead smelting at Kosaka smelter have been such secondary incombustibles as lead sulfate and lead-barium sulfate. The former is leach residue of the copper smelter flue dust and the latter originates from Iijima zinc refinery. While the most of lead concentrates produced locally has been smelted by an ISF of Hachinohe smelter in which Dowa Mining has a share.The surplus lead concentrates were processed at Kosaka by a hydrometallurgical method to convert PbS to PbSO 4 as pretreatment, and followed by simultaneous smelting together with the above secondary materials (1). Approximate output has been 1,5000 /M of lead bullion and slightly more than 2,000t/M of refined lead by adding lead bullion returned back from Hachinohe smelter (2)."

Jan 1, 1988

By C. F. Feng, L. Froyen

"In-situ processes have emerged as new and promising techniques for metal matrix composite fabrication. They offer significant technical and economic advantages over conventional processing. One of the in-situ processing routes that have been used is reactive free sintering of a mixture of powder reactants. However, materials synthesised via this route are always porous because of density differences between reactants and products. An example are the porous Al/(TiB2+Ah03) MMCs obtained by heating powder mixtures of Al+ Ti02+B with Ti02 and B in stoichiometric ratios for forming TiB2• In this study, porous Al/(TiB2+Ah03) composites were further processed by hot-pressing at temperatures above 600°C. This processing cycle was designed so that the composites could be densified. Furthermore, the reaction kinetics of the in-situ processing are studied by means of DSC analysis measured at different heating rates. The activation energies of the three intermediate steps that are involved in the reactive processing for preparing AV(TiB2+Alz03) MMCs are determined to be 923 kJ/mole, 241 kJ/mole and 235 kJ/mole respectively.XRD proved that the hot-pressed products consist of Al, TiB2 and Al203- Properties of the products are assessed by microstructural characterisation (LOM, SEM and EDS), microhardness, Young's modulus and bending tests. The results show that good microstructures, elastic properties and strengths, as well as acceptable ductilities were achieved. For the composition 79.74wt% Al-15.95wt% Ti0z-4.31wt% B, after the reactive free-sintering and hot-pressing cycles, Young's modulus is 105 GPa, bending strength is 509 MPa and maximum strain is 5.0%; for composition 88.73wt% Al-8.87wt% Ti0z-2.40wt% B, they are 89 GPa, 311 MPa and 8.2% respectively. It can be seen that the properties of products can be tailored by adjusting the relative amounts of reactants in green samples. Furthermore, for comparison reasons, Al and a binary system Al-Ti02 were identically processed as the ternary systems. Their microstructures and properties were studied."

Jan 1, 1998

By A. K. Kyllo, N. B. Gray, B. N. McCurry

"Dynamic control of the formation of a solidified layer between a pipe wall and a flowing melt enables the flow rate to be adjusted in real time. This solidified layer can be generated by using a coolant on the outside of the pipe wall to remove the required heat. The coolant, and hence the solidified layer, can be controlled remotely. The dynamic behaviour of the solidified layer was investigated by both physical experiments and mathematical modelling. The mathematical model has been developed using a finite difference technique to describe conduction through the pipe wall and solidified layer. Results from the model were consistent with previous steadystate experimental results using molten lead. Experiments are currently being carried out using molten tin in a recirculating circuit with a cooling system that is instrumented for accurate computer control to validate the model. The circuit is designed for flowrates of up to 24 kg/s (86 tph) of molten tin. Steady-state and dynamic predictions were made for the current rig.Industrial SignificanceThe current method of choice for tapping slags, metals and mattes from many metallurgical furnaces is using an oxygen lance to open the taphole and using a clay plug to close it. There are, however, some significant drawbacks in this method. The heat generated by the oxygen lance erodes the refractory lining of the taphole, as well as the clay plug, and the furnace products themselves corrode the taphole. Using an oxygen lance is also a significant safety hazard to the operators as they must work in close proximity to the furnace and be subjected to a shower of sparks while opening the taphole. Also, the flowrate of material through the taphole cannot be controlled online as the diameter of the opening cannot be varied easily. This feature means that the level of product in a furnace cannot be kept constant."

Jan 1, 1999

By Y. A. Chang, J. Woodford, C. R. Kao

Reactive diffusion studies between NbC and Si were carried out at 1300 °C under a vacuum of 10-5 torr and a uniaxial pressure of 1 MPa. The annealing time ranged from 8 to 100 hours. The Si used was single crystal silicon; the NbC was hot-pressed powder compact. A NbSi2+SiC two-phase reaction layer formed with NbSi2 as the matrix and SiC as discontinuous particles. The microstructure of the reaction product is homogeneous, dense, and fine. The NbSi2 grain size and SiC particle size are in the micron range. The growth of the reaction products follows parabolic kinetics. Extrapolation of the data to zero thickness suggests an apparent incubation time of 3.5 hours. However, for short annealing time «60 hours), the thickness data can be approximated by linear kinetics with an initial growth rate of about 2 11m/hr. Based on these experimental observations, a growth mechanism for the reactive diffusion between Si single crystal and NbC powder compact is proposed. We propose that the nucleation sites for the SiC particles are at the voids of the NbC powder compact. This proposed nucleation mechanism offers a potential way of controlling the SiC particle size by changing the void size and void density of the NbC powder compact. This hypothesis, if proven to be true, will allow us to control mechanical properties of the composites by tailoring the SiC particles formed. It is also pointed out that the microstructure requires Si to be the dominant diffusing species and to diffuse through the reaction layer, while Nb and Conly have to undergo local rearrangement.

Jan 1, 1996

By Varuzan Kevorkijan

A new method for faster production of functionally graded metal-ceramic laminates is based on reactive pressureless counterflow infiltration/penetration of a ceramic substrate with two different metallic infiltrants. The porous or dense ceramic preform is pressurelessly infiltrated or penetrated from one side by the first metallic infiltrant to the desired cross section of the preform, producing the top layer made up of the solidified infiltrant and the underlayer consisting of reactive infiltrated preform. The partly infiltrated perform is then completely infiltrated starting from the other side by the second metallic infiltrant, in this way fabricating the internal layer, consisting of the ceramic perform infiltrated with the second infiltrant and the bottom layer formed by the solidified second infiltrant. Systems already investigated include carbide, nitride and boride ceramic performs infiltrated with aluminum and magnesium alloys.

Jan 1, 2003

By Marco Olper

After two years of extensive research a new and innovative modification to the CX-EW process has been exploited. This process, called CX-EWS, avoids completely all the critical aspects of the previous process which affected the cost of the energy, of the chemicals and of The maintenance of the insoluble anodes. All these benefits reflect a saving of about 30% of The operating costs compared to the present traditional production and allow for a total operating costs of less than 6.5 cts/lb. lead (net of raw material cost). With this new technology it is allowed for the first time the treatment in the same plant facilities of both primary lead sulphide concentrate and spent batteries. The paper describes the technical and economical aspect of the new process with a feasibility study for 150,000 t/y spent battery facility throughput.

Jan 1, 1995

MODELLING FOR DESIGN AND CONTROL AT KALGOORLIE NICKEL SMELTER Modelling at KNS has been driven by a need to have better tools to answer questions about control, design and optimisation of the plant. This paper describes a number of modelling tools developed for use at KNS and how the development of modelling tools fits with a design and control strategy. In the area of control, a thermodynamic model has been developed to allow process parameters to be calculated. The model allows for the automatic selection of data from a laboratory data base, desired operating set points are input and the operating parameters are calculated. The model has the ability to adjust the burner efficiency and the furnace heat loss depending upon conditions. To assist with the testing of proposed furnace design changes, various mathematical models of the burner and shaft have been created using PHOENICS. These models are particularly well suited to combustion heat transfer and flow aspects of both the burners and shaft. Validation of these models have been based on novel sampling and measuring techniques in the shaft and also by using scale and cold models. Overall plant energy and cost structures can be analysed using a flowsheet simulation, developed to evaluate potential alterations to the plant flowsheet. This model system allows the global evaluation of process changes.

Jan 1, 1993

In accordance with the new concept described in the paper presented at the TMS annual meeting in 1989, 1 a new zinc cellhouse was constructed and successfully operated. The new concept was proposed in order to reduce energy requirements and to mechanize the electrode handling in the cellhouse. Major modifications involved the use of an electrode unit consistfog of assembled anodes and cathodes with frame bodies between each cathode and anode. The space between a cathode and an anode could be halved by this unit structure. In this paper actual operation data are summarized and discussed in comparison with the calculated figures.

Jan 1, 1990

By M. M. Kim

As-electrogalvanized coatings of pure Zn, Zn-11% Fe, and Zn-18% Fe coatings were characterized in terms of initial crystal structure and surface morphology. Samples were then subjected to heat treatments simulating the paint bake cycle of automobile manufacturers. Surface morphology changes were correlated with the process variables, and crystallo.graphic changes were interpreted by mapping heat treatment routes on the Fe-Zn phase diagram. The morphology of pure zinc electrogalvanized coatings with heat treatment from platelets to smeared platelets. The zn-11% Fe coating changes with heat treatment from tetrahedral nodules to a mixture of round and tetrahedral nodules, with the Zn-:18% Fe coating always having round nodules. Regarding crystal structure, a critical transformation time can be defined at any selected temperature, below which the crystal structure does not change. This temperature is related to iron content.

Jan 1, 1990

By A. Onozaki

The Iijima Refinery was put into operation in 1972 and today has an annual production capacity of 156,000 tons of SHG electrolytic zinc. At the Iijima Refinery, the recoveries of gold and silver are 98.0% and 98.2%, respectively. Gold contained originally in the zinc concentrates reports in the Cu-Pb-Ag residue produced in the residue treatment process. Silver contained in the concentrates is distributed between the Cu-Pb~Ag residue and the copper cake produced in the purification process. The Cu-Pb-Ag residue, which contains gold and silver, is sent to the Oyachi flotatfon plant of the Kosaka Smelter; about 82% of the gold and about 85% of the silver are recovered in the copper flotation concentrate.. In this paper, the distribution of gold and silver in the Iijima. Refinery is discussed and operational results of the Oyachi flotation plant are presented.

Jan 1, 1990

By A. R. Udupa

The reduction roasting behavior of chalcopyrite has been investigated using various combinations of a desulfurizing agent, i.e., CaO or Na2CO3, and a reductant, i.e., CO, H2 or C. Using these, combinations the sulfur is removed from the mineral as CaS or Na2S rather than SO2 as is the case with conventional copper smelting and converting. The laboratory reduction ex¬periments were conducted using thermogravimetric analysis (TGA) and boat tests of mixed combinations of fine particulate reactants subjected to a continuous gas stream. The degrees of metallization were determined by both weight loss and chemical analysis methods and the products examined using optical and scanning electron microscopy and electron probe microanalysis. The percent reduction after one hour at 900°C ranged from 60% to 94%. From these data It was possible to provide postulations as to the controlling reduction mechanisms.

Jan 1, 1983

By D. Y. Wang, G. Y. Sha, X. L. Shen, D. R. Gu

The study of the volatilization kinetics of zinc and lead in pellets made of zinc-leadbearing dust mixed with coal powder, in a nitrogen atmosphere and at a temperature range between 1100 °C and 1300 °C, shows that the reduction temperature has a significant effect on the volatilization rates of zinc and lead, and that both the particle size of the coal powder and the extra carbon content has no effect on the volatilization rates. The obtained activation energies for the volatilization of zinc and lead are 79.42kJ/mol and 88.74kJ/mol respectively. The volatilization rate of zinc is controlled by the reaction between the zinc oxide and carbon monoxide while that of lead is controlled by the lead evaporation reaction, and the diffusion of gaseous lead through the gas boundary layer covering the surface of the reduced liquid lead.

Jan 1, 2000

By Donald R. Sadoway

Molten salt electrolysis is a proven technology for the extraction of metals -- all the world's primary aluminum is produced in this manner. The unique properties of molten salts, also make them excellent media in which to treat a variety of forms of waste. Of special .note in this regard is electrolysis in molten oxides, a .concept put forward by. the author, initially as a ."clean technology" for producing primary metal. However, in the context of waste treatment, electroly-sis in molten oxides is a process offering the prospect of changing the. valence of dissolved heavy metals while making pure oxygen gas as the main by-product .Laboratory tests conducted at a temperature of 1550°C on chromate sludge dissolved in an melt composed of Al2O3 and MgO have confirmed electrochemical production of oxygen on a carbon-free anode.

Jan 1, 1996

By Katsuyoshi Tatenuma

"In order to mitigate the effect of global warming by preventing the accumulation of atmospheric CO2, a permanent fixation method of surplus CO2 as an insoluble mineral onto the sea bottom is proposed. As the proposed reduction method of atmospheric CO2, the concrete concept of this method is to form an insoluble carbonate mineral (CaCO3) by direct electrolysis of the seawater; Ca2++2HCO3 -+OH- ? ?CaCO3(insoluble)+CO3 2- (soluble)+H++H2O <not as coral reef reaction>, are directly disposed of itself onto the sea bottom. By this treatment, a concentration of carbonate is reduced in the section of superficial seawater, and therefore the absorption capacity of atmospheric CO2 increases depending upon the shift of chemical carbon equilibrium between the mass of superficial seawater and the atmosphere. As no additives are required, or no secondary waste are produced, the proposed method assuming as green-orientated, has possibility to resolve fundamentally the problem of global warming in a green orientate manner.IntroductionRecently, the amount of atmospheric CO2 has been exponentially increasing and it is a main greenhouse effect gas causing the global warming [1, 2]. The concentration of atmospheric CO2 has increased more than 30% (370ppm in 2001) during only last two centuries, therefore approximately 750 Gton-C of CO2 currently exist in the atmosphere, in which 180 Gton-C of CO2 are accounted for the increment during two centuries [1, 3, 4]. In order to avoid the progressive increase of CO2 global abundance, 3 Gton-C of the incrementing amount per year [4], have to be removed annually from the atmosphere."

Jan 1, 2008

By Dilip Banerjee

"This paper discusses the Advanced Technology Program (ATP)'s support over the last decade to the development and use of process modeling as a tool to address some of the challenges faced by the U.S. metal casting industries. A particular focus will be given to highlight how process modeling can be used to improve the manufacturability of components needed for high performance and critical applications. The challenges associated with the design and production of thin-walled, cast parts with intricate and complex internal geometries will be discussed. Modeling issues associated with the control of the final grain structure in the solidified parts will also be addressed. This paper will describe the advantages of using appropriate mathematical models for designing new alloys for use in various applications.Finally, the role that ATP has played in uplifting the U.S. technological base through partnerships with industry and academia in high-risk research in order to bring to market new and improved products for the broader benefit of the nation will be discussed.ATP's BackgroundIn the 1980s, U.S. industries were losing market share to low-cost, high-quality manufacturers from Asian countries. Corporate leaders and policy makers determined that in order to sustain and grow market share, U.S. industries needed to improve their competitiveness and productivity through product and process innovation. There was evidence that companies were systematically under-investing in leading-edgetechnologies and failing to complete the development of new technologies [l]. There were also arguments in academic circles that pointed to a potential market failure in the area of early-stage technological developments. These concerns provided impetus for creation of the Advanced Technology Program (ATP) within the National Institute of Standards and Technology through the Omnibus Trade and Competitiveness Act of 1988. Through a rigorously competitive, cost-shared partnership with industry, ATP fosters the development and broad dissemination of high-risk technologies that offer the potential for significant broad-based economic benefits to the United States."

Jan 1, 2004

By Hector Henao

To provide thermodynamic data for converting the nickel matte to liquid nickel, an experimental study was conducted in the phase equilibrium between the Ni-S alloy and the CaO-Al2O3 based slag melted in a MgO crucible at 1873 K under controlled Pso2 of 10.1 kPa and Po2 in a range between 2.5x 10-and 10.1 Pa by using CO-CO2-SO2 gas mixtures. The content of nickel in the slag at Po, of 10.1 Pa, above which solid NiO is expected to precipitate in the equilibrium state, was found to be 4, I mass% and the contents of sulfur and oxygen in the nickel melt were 0.4 and 02 mass%, respectively. ft was clarified that increase in the temperature reduces the solubility of nickel in the slag and the contents of sulfur and oxygen in the alloy, The distribution of minor elements such as gold, silver, copper, cobalt, iron, arsenic and antimony between the Ni-S alloy and the CaO-Al2O3 based slag was also studied. The distribution ratios of iron and cobalt, defined by (%X in slag)/[%X in alloy] where X is the minor element, are larger values than that of nickel, while those of copper, silver and antimony are similar to that of nickel. The distribution ratios of arsenic and gold are lower than that of nickel in the higher range of oxygen partial pressure.

Jan 1, 2003

By Chunhua Liao, Chao Peng, Guangsheng Huo

To get the separation of tungsten and molybdenum, we adjusted the pH of the solution to 7, at which tungstate (WO4 2-) will be polymerized into HW6O21 5-, while molybdate will still exist in the form of MoO4 2-. Two strongly basic anion exchange resins (D201, D213) were experimented for the separation of tungsten and molybdenum. The results of condition experiments indicate that D213 resin performs better in the treatment of lower concentration solution A (WO3 10g/L, Mo 4.12g/L) with a separation factor as high as 10.64. While D201 resin is more suitable for the high concentration solution B (WO3 70g/L, Mo 28.97g/L) with a separation factor of 6.9. The results of column testing performed on D213 resin show that the solution after loading process with a mass ratio of Mo/WO3 = 50 and the desorption solution with a mass ratio of WO3/Mo = 27 can be obtained

Jan 1, 2014

By Patrick R. Taylor

Keywords: Thermal Plasma, Electroreduction, Electrolysis, Transition metals, Waste treatment, Molten oxides, Chromium oxide. An innovative process to treat transition metal oxide waste materials from diverse sources is presented. This technology involves using reverse-polarity DC plasma driven electrolysis in molten oxides. The process results in the recovery of the transition metal and other heavy metals from waste. By-products generated throughout the processing was converted to environmentally acceptable slag. The significance of this technology is that the treatment of the waste is accomplished in one step which in turn lowers the cost of remediation. Moreover, this process uses high temperature properties of thermal plasmas, which makes it possible to use molten oxides instead of halides as electrolytes. Chromium was successfully reduced from chromium oxide through the plasma driven electro-reduction process. It was shown that the selection of the appropriate ionic conducting oxides was critical for the formation of a slag that would enhance the reduction of chromium oxide.

Jan 1, 2004