Foaming of slags under dynamic conditions

Slag foaming under dynamic conditions has been studied in laboratory scale to examine the influence of properties commonly used to describe the foaminess and foam stability of slags under steady-state conditions. Synthetically produced slags with compositions relevant to tool steel and stainless steel production were studied through X-ray equipment in measurements simulating the dynamic conditions found in real processes. It is found that the dynamic systems display a more complex behavior than systems Under steady state. Traditional theories for foaming do not seem to be valid for slag foaming under dynamic conditions. The foam displays a fluctuating behavior, which the presently available models are not able to take into account. The concept of a foaming index does not seem to be applicable, resulting in the need for alternative models.

Finlandismer i fokus : Finlandssvenska studerandes syn på ett urval finlandismer och allmänsvenska ord och uttryck

Syftet med studien är att undersöka sydfinlandssvenska högskolestuderandes kännedom om och inställning till ett urval finlandssvenska ord och uttryck samt till dessa ords allmänsvenska motsvarigheter. För att undersöka detta har jag gjort en enkätundersökning bland svenskspråkiga högskolestuderande i Helsingfors. Jag undersöker i vilken utsträckning informanterna använder finlandssvenska ord och uttryck och i vilken utsträckning allmänsvenska. Jag undersöker även vilka finlandssvenska ord och uttryck de använder mest och vilka minst, samt vilka allmänsvenska ord och uttryck de använder mest och vilka minst. Dessutom undersöker jag om informanternas språkliga bakgrund har ett samband med deras kännedom om och användning av finlandssvenska respektive allmänsvenska ord och uttryck. Avsikten med den här undersökningen är att öka kunskapen om hur unga finlandssvenskar förhåller sig till sin finlandssvenska varietet samt till den allmänsvenska varieteten som de i vuxen ålder förutsätts behärska åtminstone i någon mån. Idén till enkätundersökningen kommer från Margareta Södergårds och Sofie Tjärus studie Blivande barnträdgårdslärares syn på finlandismer (2008). Urvalet finlandismer kommer från en mindre undersökning Goda och onda finlandismer som Mikael Reuter (2004) har gjort bland en grupp finlandssvenska och sverigesvenska språkvårdare. Sammanlagt ingår 55 finlandismer av olika slag i enkäten. För varje finlandism finns det även en eller fler allmänsvenska motsvarigheter och sammanlagt ingår därför 122 ord och uttryck i enkäten. Mina informanter är 162 studerande vid två svenska högskolor i Helsingfors. För att få reda på relevanta bakgrundsfakta om informanterna har jag använt samma formulär som Therese Leinonen i Svenskan i Finland ett språk i kläm? (Leinonen & Tandefelt 2000). Jag har utgående från informanternas generella språkanvändning delat in dem i tre grupper. En grupp vars vardag är finskdominerad, en vars vardag är svenskdominerad och en vars vardag utspelar sig till ungefär lika stor del på svenska som på finska. Undersökningen är kvantitativ och för att behandla materialet har statistikprogrammet SPSS använts. Studien visar att informanterna förhåller sig rätt lika till finlandismerna och de allmänsvenska orden och uttrycken. De känner ungefär lika bra till de finlandssvenska och de allmänsvenska orden och uttrycken, men de prefererar ändå i viss mån finlandismerna framför de allmänsvenska orden och uttrycken. Mina informanter förefaller i viss mån vara mer accepterande mot finskpåverkade finlandismer än vad Reuters (2004) informanter är, och de förhåller sig mindre positiva till metaforiska uttryck än vad Reuters informanter gör. Informanter med en svenskspråkig vardag verkar använda allmänsvenska ord och uttryck i högre utsträckning än vad informanterna med en finskspråkig vardag gör. Resultaten tyder dessutom på att informanterna med en svenskspråkig vardag också känner till fler allmänsvenska ord och uttryck även om de inte alltid själva är beredda att använda dem. Studien visar även att informanter med en svenskspråkig vardag använder en del metaforiska uttryck mer än vad informanterna med en finskspråkig vardag gör. Det är överlag tydligt att undersökningens informanter, finlandssvenska högskolestuderande från södra Finland, varken har en speciellt stor kännedom om metaforiska uttryck eller en speciellt positiv inställning till dessa. Bristande behärskning av metaforiska uttryck, idiom och kollokationer kan ses som ett första steg mot språkförlust och sett ur den synvinkeln är resultatet oroväckande. Det stärker den rådande uppfattningen att allt inte står helt rätt till med den svenska språkbehärskningen bland unga finlandssvenskar.

A modified sulphide capacity function

The sulphide capacity as originally defined by Fincham and Richardson is a strong function of composition in pseudobinary oxide melts of interest in extractive metallurgy. From an analysis of data available in the literature, it is shown that sulphide capacity is directly proportional to the activity of the basic oxide in the melt, within the uncertainty of experimental data. A single parameter is sufficient to describe the sulphide capacity of a binary slag system under isothermal and isobaric conditions. The correlation indicates that the activity coefficient of the sulphide ion or the neutral base metal sulphide dissolved in the melt is independent of composition in pseudobinary melts within experimental uncertainty. Structural variations in the melt with composition do not seem to affect the activity coefficient of the sulphide. A modified sulphide capacity function is defined which makes the treatment more elegant and greatly simplifies data storage and retrieval. The modified function is not based on any model for the melt.

Enhancement in Bath Mixing and Plume area in a New Degassing Process - A Computational Fluid Dynamic Study

Reaction between the various species in slag and metal phase is usually mass transfer controlled. There have been continuous efforts to increase the reaction efficiency in slag-metal system, especially during decarburization of steel to produce the ultra low carbon steel (ULCS) in secondary steelmaking. It has been found that the surface reaction is a dominant factor in the final stage of decarburization. In the initial stage, the inner site reaction is major factor in the refining process. The mixing of bath affects the later reaction. However, the former reaction (surface reaction) is affected by the plume size area at the top of the metal surface. Therefore, a computational study has been made to understand the fluid dynamics of a new secondary steelmaking process called Revolutionary Degasser Activator (REDA) to study the bath mixing and plume area. REDA process has been considered as it is claimed that this process can reduce the carbon content in steel below 10ppm in a less time than the other existing processes such as RH and Tank degasser. This study shows that both bath mixing and plume area are increased in REDA process facilitating it to give the desired carbon content in less time. Qualitative comments are made on slag-metal reaction system based on this finding.

Reduction of electric arc furnace slags in stainless steelmaking - Part 2 Mechanism of CrOx reduction

The mechanism of reduction of iron and chromium oxide from synthetic electric are furnace stainless steelmaking slags has been studied. The activation energy for reduction of FeO depends on the FeO content of the slag and the nature of the product formed. The rate of reduction of both FeO and Cr2O3 is controlled by diffusion of ions in the slag phase. The reduction of Cr2O3 primarily takes place at the slag/Fe-C droplets interface. IS/1352b. (C) 1998 The Institute of Materials.

Reduction of electric are furnace slags in stainless steelmaking - Part 1 Observations

Simultaneous reduction of iron and chromium oxides from synthetic electric are furnace stainless steelmaking slag in a graphite crucible has been studied. Above the melting point of iron the reduction of iron oxide leads to a carbon saturated Fe-C melt, but below the melting point of iron initially solid iron or iron carbide forms on the crucible surface. Only when a certain number of Fe-C droplets are formed does the reduction of chromium oxide start to form an Fe-Cr-C alloy. The reaction proceeds with pronounced foaming which depends on the basicity, temperature, and iron oxide content of the slag. IS/1352a (C) 1998 The Institute of Materials.

Cold model study of local liquid holdup in the dropping zone using x-ray

It is important to know and to quantify the liquid holdups both dynamic and static at local levels as it will lead to understand various blast furnace phenomena properly such as slag/metal.gas.solid reactions, gas flow behaviour and interfacial area between the gas/solid/liquid. In the present study, considering the importance of local liquid holdup and non-availability of holdup data in these systems, an attempt has been made to quantify the local holdups in the dropping and around raceway zones in a cold model study using a non-wetting packing for liquid. In order to quantify the liquid holdups at microscopic level, a previously developed technique, X-ray radiography, has been used. It is observed that the liquid flows in preferred paths or channels which carry droplets/rivulets. It has been found that local holdup in some regions of the packed bed is much higher than average at a particular flow rate and this can have important consequences for the correct modelling of such systems.

Gibbs energies of formation of intermetallic phases in the systems Pt Mg, Pt Ca and Pt Ba and some applications

The standard Gibbs energies of formation of platinum-rich intermetallic compounds in the systems Pt-Mg, Pt-Ca, and Pt-Ba have been measured in the temperature range of 950 to 1200 K using solid-state galvanic cells based on MgF2, CaF2, and BaF2 as solid electrolytes. The results are summarized by the following equations: ΔG° (MgPt7) = −256,100 + 16.5T (±2000) J/mol ΔG° (MgPt3) = −217,400 + 10.7T (±2000) J/mol ΔG° (CaPt5) = −297,500 + 13.0T (±5000) J/mol ΔG° (Ca2Pt7) = −551,800 + 22.3T (±5000) J/mol ΔG° (CaPt2) = −245,400 + 9.3T (±5000) J/mol ΔG° (BaPt5) = −238,700 + 8.1T (±4000) J/mol ΔG° (BaPt2) = −197,300 + 4.0T (±4000) J/mol where solid platinum and liquid alkaline earth metals are selected as the standard states. The relatively large error estimates reflect the uncertainties in the auxiliary thermodynamic data used in the calculation. Because of the strong interaction between platinum and alkaline earth metals, it is possible to reduce oxides of Group ILA metals by hydrogen at high temperature in the presence of platinum. The alkaline earth metals can be recovered from the resulting intermetallic compounds by distillation, regenerating platinum for recycling. The platinum-slag-gas equilibration technique for the study of the activities of FeO, MnO, or Cr2O3 in slags containing MgO, CaO, or BaO is feasible provided oxygen partial pressure in the gas is maintained above that corresponding to the coexistence of Fe and “FeO.”

Influence of Bottom Bubbling Rate on Formation of Metal Emulsion in Al-Cu Alloy and Molten Salt System

In steel refining process, an increase of interfacial area between the metal and slag through the metal droplets emulsified into the slag, so-called ``metal emulsion'', is one prevailing view for improving the reaction rate. The formation of metal emulsion was experimentally evaluated using Al-Cu alloy as metal phase and chloride salt as slag phase under the bottom bubbling condition. Samples were collected from the center of the salt phase in the container. Large number of metal droplets were separated from the salt by dissolving it into water. The number, surface area, and weight of the droplets increased with the gas flow rate and have local maximum values. The formation and sedimentation rates of metal droplets were estimated using a mathematical model. The formation rate increased with the gas flow rate and has a local maximum value as a function of gas flow rate, while the sedimentation rate is independent of the gas flow rate under the bottom bubbling condition. Three types of formation mode of metal emulsion, which occurred by the rupture of metal film around the bubble, were observed using high speed camera. During the process, an elongated column covered with metal film was observed with the increasing gas flow rate. This elongated column sometimes reached to the top surface of the salt phase. In this case, it is considered that fine droplets were not formed and in consequence, the weight of metal emulsion decreased at higher gas flow rate.

Modeling of Ascending/Descending Velocity of Metal Droplet Emulsified in Pb-Salt System

Metal-slag emulsion is an important process to enhance the reaction rate between the two phases; thus, it improves the heat and mass transfer of the process significantly. Various experimental studies have been carried out, and some system specific relations have been proposed by various investigators. A unified, theoretical study is lacking to model this complex phenomenon. Therefore, two simple models based on fundamental laws for metal droplet velocity (both ascending and descending) and bubble velocity, as well as its position at any instant of time, have been proposed. Analytical solutions have been obtained for the developed equations. Analytical solutions have been verified for the droplet velocity, traveling time, and size distribution in slag phase by performing high-temperature experiments in a Pb-salt system and comparing the obtained data with theory. The proposed model has also been verified with published experimental data for various liquid systems with a wide range of physical properties. A good agreement has been found between the analytical solution and the experimental and published data in all cases.

Soil stabilization with waste materials based binder

This paper describes a laboratory trial to study the effectiveness of a waste-based binder to stabilize expansive soils. The proposed binders viz., Fly ash and/or Ground granulated Blast furnace slag (GGBS) were mixed with the expansive soil along with a small amount of lime to increase soil pH and enable pozzolanic reactions. The geotechnical characteristics of the various combinations of samples were investigated through the compaction tests, unconfined compression tests etc. It was found that the addition of GGBS with and without fly ash and lime has significant influence on the geotechnical characteristics of the soil.

Some Thermodynamic Aspects of the Oxides of Chromium

To understand Cr emissions from slag melts to a vapor phase, an assessment of the stabilities of the chromium oxides at high temperatures has been carried out. The objective of the present study is to present a set of consistent data corresponding to the thermodynamic properties of the oxides of chromium, with special reference to the emission of hexavalent chromium from slags. In the current work, critical analysis of the experimental data available and a third analysis in the case of Cr2O3 have been carried out. Commercial databases, Fact Sage and ThermoCalc along with NIST-JANAF Thermochemical Tables, have been used for the analysis and comparisons of the results that are presented. The significant discrepancies in the available data have been pointed out. The data from NIST-JANAF Thermochemical Tables have been found to provide a set of consistent data for the various chromium oxides. An Ellingham diagram and the equations for the Delta G degrees (standard Gibbs free energy change) of formation of CrOx have been proposed. The present analysis shows that CrO3(g) is likely to be emitted from slag melts at high oxygen partial pressures. (C) The Minerals, Metals & Materials Society and ASM International 2014

Biodiesel Exhaust Treatment with Dielectric Barrier Discharges Coupled with Industrial Waste Byproducts

Biodiesel run engines are gaining popularity since the last few years as a viable alternative to conventional petro-diesel based engines. In biodiesel exhaust the content of volatile organic compounds, oil mist, and mass of particulate matter is considerably lower. However, the concentration of oxides of nitrogen (NOx) is relatively higher. In this paper the biodiesel exhaust from a stationary engine is treated under controlled laboratory conditions for removal of NOx using dielectric barrier discharge plasma in cascade with adsorbents prepared from abundantly available industrial waste byproducts like red mud and copper slag. Results were compared with gamma-alumina, a commercial adsorbent. Two different dielectric barrier discharge (DBD) reactors were tested for their effectiveness under Repetitive pulses /AC energization. NOx removal as high as 80% was achieved with pulse energized reactors when cascaded with red mud as adsorbent.

Pulverized-coal combustion in Wall-Protecting-Jets combustor (WPJC)

A new type of pulverized-coal combustor, called "Wall-Protecting-Jets Combustor" (hereafter, WPJC has been proposed, designed and studied with both CFD (Computational Fluid Dynamics) and experimental methods. The WPJC is based on a novel concept in which all inlet jets are along the combustor wall. Pilot combustion experiments were conducted to investigate the combustion performance of WPJC. Two-phase flows and pulverized-coal combustion were simulated to study the mechanism of),WPJC using the commercial software FLUENT. The results show that the WPJC has many remarkable advantages: wall-protection by the cold jets without the use of refractory materials; low-temperature and three-stage combustion with low NOx emission; negligible ash/slag-deposition; multiple functions with convenient switching between them; effective adjustment of the combustion intensity and the ignition position.

Some implications of the volcanic theophany of YHWH on his primeval identity

Abstract: YHWH’s theophany and mode of action are frequently evoked in the Bible as a volcanic event. It is shown here that this representation, of central importance in the story of the Sinai Covenant, is probably not anchored in any specific volcanic eruption experienced by the Israelites in the past. In Antiquity, volcanic activity was specifically associated with the gods who patronized metallurgy, given the homology between lava flowing from a volcano and slag released from a furnace at smelting. Evidence towards such a link is also identified in the Bible. Accordingly, rather than being simply a literary artifice imaging the outstanding powers of YHWH, volcanism may reflect the existence of metallurgical roots in Israelite theology. This contention is supported by Biblical evidences associating YHWH with metal production: (i) his primeval dominion in mining areas, (ii) his special worship by metalworkers, (iii) the representation of his celestial universe as a giant furnace. It is concluded that the volcanic representation of YHWH’s theophany and mode of action reveal a surprising level of preservation of the metallurgic religious traditions in the ancient Israelite theology.