results in larger bubbles and less stable foams. The solid particles also act as nucleation sites for the bubbles. The chemical reactions occurring during the removal of impurities determine the chemical composition of the basic-oxygen-furnace slag [1, 3, 5]. Using tongs remove the crucible from the furnace and pour its entire contents into a pouring mold. furnace (carbon steel production) CAS names 1 IUPAC names 20 Trade names 6 Other identifiers 1 Print infocard Open Brief Profile Create your account. The second reaction represents a direct reaction between gaseous oxygen and carbon in bath, whereas the first reaction is a direct iron oxide reduction reaction by carbon in slag. investigation of the variations of the compositions of hot metal and slag as well as the temperature of hot metal during tapping in a commercial blast furnace. Ground Granulated Blast Furnace Slag (GGBS) The importance of Ground Granulated Blast Furnace Slag (GGBS) lies in its greener way to become a substitute in concrete material. However, an excessive amount of solid particles prevents the bubbles from ascending through the slag. The slag furnace works similarly to the vanilla furnace, but has an extra output slot. The size of its particles is less than 45 microns and specific surface area is about 400 to 600 m 2 /kg. High Alumina Slag and Blast Furnace Operation. The procedure of removal of iron is the blast furnace. For example, an excessive amount of slag may result in increased furnace refractory wear, more slag transfer to the pouring ladle (increased probability of Table 2: Formulation of hydraulically bound mixtures Formula 1 Formula 2 Formula 3 Formula 4 CBFS 80 80 80 80 Therefore, a unique plant study was conducted on a commercial blast furnace during a 68 hour period where slag and hot-metal samples were taken with a 10-minute interval. According to this definition, a glass is noncrystalline material obtained by a melt-quenching process. The inferences from the curves are given below. Roads constructed using LD slag demonstrate reduced rutting. So, coke bed is floating on the slag surface and reacting with oxides. Slag-tap furnace definition is - a blast furnace or pulverized-fuel furnace with a tap opening in the bottom for removal of slag. It has also been reported that the slag foaming process can save 3 % to 10 % and 25 % to 63 % of energy and refractory consumption, respectively. of the EAF slag Fig 1 shows a schematic diagram of chemical reactions for slag foaming in EAF. 2.5. the ladle furnace is higher spread of incoming sulphur, as shown in Figure 4. The Boudouard reaction and the reduction of FeO by solid carbon are highly endothermic reactions, while the reduction of Fe2O3 by CO is energy-neutral and the reduction of FeO by CO is only slightly exothermic. Iron ores such as haematite contain iron(III) oxide, Fe 2 O 3.The oxygen must be removed from the iron(III) oxide in order to leave the iron behind. References 15 and The foaming slag also contributes to stabilization of the arc, ensuring a higher efficiency. Silicon dioxide reacts with calcium oxide to form calcium silicate (called slag) which is liquid in the furnace. Blast furnace slag is recovered by melting separation from blast furnaces that produce molten pig iron. The iron reduction in this zone is mixed controlled by mass transfer and chemical reaction mechanisms. Raw Materials:. Smelting process optimization In the normal slag operating region, changes in the basicity would have Depending upon the particular blast furnace operation, the slag is composed primarily of sulfur and oxides of aluminum, calcium, magnesium, and silicon. Remembering the formula for slag. The basic components provide the O2 ions to the melt and the acid components bind them. In EAF steelmaking, it has been found that, towards the end of the process, the foam becomes less stable and the foam height decreases. Blast Furnace and Process Description:- Iron blast furnace is a vertical shaft, which is used to melt the iron ore and to produce hot metal by heat exchange and chemical reaction.The burden charge consisting of iron oxide, flux and coke and it provides through the throat from the top of the furnace. This oxygen reacts with the existing carbon forming CO (carbon monoxide) bubbles. The slag has a lower density than steel and therefore floats on top of the molten steel. In step 3, oxygen is injected into the slag, to cause oxidation of the carbon present in the slag. furnace (carbon steel production), Slags, steelmaking, steelmaking, EAF C (RSFC), Additional physico-chemical properties of nanomaterials, Toxicokinetics, metabolism and distribution, electrical arc furnace slag carbon steel production. In this process steel scrap with additions of fluxes (e.g., lime[stone] and/or dolomite) are heated to a liquid state by means of an electric current. Most assayers pound the lead button into a cube. Molten iron and slag are withdrawn at the bottom. Steel Slag – Electric Arc Furnace Slag lime, additions Measures to influence the quality of slags Process stage 1) Measures to influence the quality Influenced properties Raw material preparing O Melting process Heat treatment Processing selection, arrangement and pre-treatment of raw materials relating to the chemical comp. Slag foam is beneficial for the EAF steelmaking process in terms of the large surface area formed and the protection provided against the direct contact of the melt with the atmosphere. Iron Ore e.g. It has been observed that slag viscosity decreases with an increase in basicity, but when it passes a critical value and a solid phase is precipitated, it increases once again. T] with the slag deformation temperature as the turning point. Please upgrade your Internet Explorer to a newer version. Thus, the scrap intercepts most of the arc radiation and little passes through to the sidewalls. 1.3 Mineral Reactions in the Pelletising Process The mineral reactions in LKAB’s blast furnace pellets during the pelletising process have been thoroughly investigated by Niiniskorppi (2004). increasing electric arc furnace (EAF) performance. Electric arc furnace slag is produced during the manufacture of crude steel by the electric arc furnace (EAF) process. Higher values than this, at the beginning of a heat, promoted heavy slag slopping affecting operations in the working floor and making unstable electric arcs hindering operations with long arcs of high voltage and low current. The diagram shows the reaction sites during injection of carbon during steel melting-refining processes in an EAF. True foaming is not to be confused with simple gas hold-up of bubbles in a liquid. It is normally seen that with only 20 % volume fraction of solid particles in the liquid slag, there is a two fold increase in the slag viscosity and zone for heterogeneous foaming can be considerably enlarged, partially embracing the non-foaming zone, as is shown by the dotted line in Fig 2. This site is not fully supported in Internet Explorer 7 (and earlier versions). This allows for a higher productivity in the furnace, since it increases the heat transfer between electrode and the molten metal. The gas flow is generated when carbon (C) and gaseous oxygen (O2) is added to the slag and the metal bath respectively. The density of the slag affects the foam height. In addition to this, the foam helps to reduce noise from the EAF, which provides a better working environment. The oxides are then reduced in a blast furnace that is 80–100 feet high and about 25 feet in diameter (Figure \(\PageIndex{2}\)) in which the roasted ore, coke, and limestone (impure CaCO 3) are introduced continuously into the top. Hence, the unit of the FI is time which is normally in seconds. Extraction of Iron in a blast furnace. These physical properties are, in turn, dependent of the temperature of the system and the slag composition. The foaming of the slag is significantly affected by the gas flow into the furnace, but is also affected by the slag properties, the latter controlled by the viscosity, density and surface tension. Although the slag acts as a protective layer against the oxidation of the iron, it usually represents a significant cost item, depending on its composition and the quantity that is present. This occurs at around 20 % to 40 % FeO depending on other conditions. Thus, the ability to create new surfaces, which occurs when bubbles are formed in the slag, is facilitated when the surface tension is low. This is called the Marangoni effect. The roof is also made of water-cooled panels and has three circular openings, equally spaced, for insertion of the cylindrical electrodes. Driving force for slag foaming is a pneumatic energy provided by CO generation during the process of the melting-refining in the EAF. research, method of production and optimum conditions for foamy slag in 200 tons electric arc furnace were investigated. blast furnace slag compositions and higher target viscosities, the resulting temperature is likely to yield a multiphase slag, where the solids contribute significantly to the increase in viscosity. This in turn protects the refractories from wear, which reduces the amount of down-time for maintenance work. The reaction is given by C (injected) + (FeO) = Fe + CO. CO gas for foaming is also produced by decarburization of the metal given by the reaction C (in metal) + 1/2 O2 = CO. Slag flows to the bottom of the furnace where it … In a system of liquids, a gradient in surface or interfacial tension can induce motion. Close Find out more on how we use cookies. Blast furnace slag in granulated form procured from Visakhapatnam Steel Plant, Visakhapatnam, India. Electric arc furnaces are the largest users of electric energy in industry. FI of slag determines these properties. The current long-arc process maximizes the energy transfer to the scrap surrounding the electrodes and arcs. The foaming index (FI) is an important parameter for the slag foaming. Foaming slag can be slowly built up as the scrap melts and the furnace sidewalls and roof become progressively exposed to heat radiating from the arcs, reaching a maximum height during the refining stage of the heat. As per a study, the variations in foaming slag quality can account for + /- 0 kWh/t in demand for the electrical energy. Molecular Formula Unspecified 4. The quality of the slag foaming is an important factor in the EAF steelmaking process since it ensures that the heat from the liquid bath is not lost through the EAF walls. Preheating of the silica sand and granulated blast furnace slag (GBF) particulates were carried out in a muffle furnace at 3000 C for 3 hours to get rid of the any moisture presence in them. (adsbygoogle = window.adsbygoogle || []).push({}); There is normally a dense layer of slag beneath the foam. The main function of the furnace is the reduction of the matte and metal level in the slag. Comparison of the slag viscosity calculated from the formula in this study and the measured viscosity of practical blast furnace slag during the cooling stage (1600 K–1800 K). The composition of slag varies with the type of metal being melted in a coreless furnace. Sadly, now shut down! This happens because initially as the FeO content increases, the rate of fist reaction and CO generation increases and, hence, the foaming increases. The entire stock in a furnace may weigh several hundred tons. The various formulations are reported in Table 2. However, as the FeO content increases, the slag viscosity decreases and the density increases causing the foam bubbles to drain more rapidly, to decrease and the foam to decay. EAFS in common with most steel slags, is subject to slight dimensional expansion until it fully hydrates. At the initial moment of the contact of carbon and slag the direct reduction reaction takes place, forming a gas film separating solid carbon and liquid slag phases as it … Electric furnace slag cleaning uses coke as a reductant. These reactions are responsible for the CO formation. The slags that form in electric furnace melting result from complex reactions between silica (adhering sand and dirt from casting returns), oxides from scrap, other oxidation by-products from melting and reactions with refractory linings. All Rights Reserved © 2019, Design & Developed By: Star Web Maker. O 2; limestone (calcium carbonate) to remove certain impurities like silica. Especially slag cleaning furnaces have supplied more than 20 in the last 40 years. In the slag foaming process, carbon is injected into the slag, reacts with iron oxide in the slag to produce CO gas, which foams the slag. Normally, gases resulting from chemical reactions tend to foam the slag with smaller bubbles, whereas the injection of gas phases (oxygen, argon, etc.) GGBS being a waste material, it needs proper method for disposal. Figure 5 shows the viscosity variation in a CaO-SiO 2- Ground Granulated Blast Furnace Slag(325 mesh). To obtain a suitable viscosity, it is important to have an appropriate basicity of the slag. Slags from these processes are usually strong and rock-like, with the potential for use as aggregates in a variety of applications. Acid slags have the highest foaming index forming capabilities which can be called as homogeneous foaming. Foamy slag formation can be divided into 3 steps. clinker, blast-furnace slag, siliceous and calcareous fly ash] 6fd6afc5-94cd-426e-9b34-2f8c0af4cd3f Cement Standard Formula - 10 [Portland-composite cement, Composite cement (slag – pozzolana) Portland cements with three main constituents: clinker, blast-furnace slag, natural or natural calcined pozzolan] 992e3d4c-69d9-4dea-b912-4b28747e93b2 Date: 5/1/1983. Team Members: Darrell Markewitz, Marcus Burnham, Neil Peterson, The reason to run this system was a preliminary test towards a possible public demonstration at the 'Earth Air Celtic Festival', Goderich, for early August 2012. 2.2. All these reactions are CO formers giving stirring energy for mass transfer between metal slag, carbon, and gas phases and they can be considered as a necessary condition for slag foaming. The primary and secondary relationship that affects the 24h water absorption rate of the product is: the mixing amount of cement, blast furnace slag, quicklime and fly ash. Gas injection, however, produces larger bubbles and less stable foam. Slag has a greater PSV (Polished Stone Value): i.e., greater resistance to wear. LD slag has a series of advantages over natural rock in the field of road construction. The consequences of a good foaming slag in the EAF and its proper control include (i) the decrease in harmonics due to electrode immersion in the slag can increase power at the same transformer settings by 6 % to 9 %, (ii) an increase in power by 15 % when the electrode tips are 300 mm to 600 mm deep in the slag because of the hotter arc plasma around the electrode tip, and (iii) a good foaming slag allows oxygen-fuel burners (when used) to blow into the slag, increasing energy efficiency of the burners from 40 % to 70 %. It can be seen from the diagram that CO formation is a very complex function of several process variables consisting of size, type and mass flow rate of carbonaceous material, flow rate of carrier gas, carbon content in bath, slag chemistry, and slag-metal interfacial area etc. satyendra; May 27, 2013; 6 Comments ; alumina, Basicity, magnesia, slag, Slag basicity, Slag drainage, Slag fluidity, viscosity,; High Alumina Slag and Blast Furnace Operation. This website uses cookies to ensure you get the best experience on our websites. References 11 to 13 are the only reported arc emission spectrum measurements on the industrial electric arc furnaces. For most ores, it will produce an ingot with a low (20%) chance of making two instead of one, and also some Stone. Slag is the glass-like by-product left over after a desired metal has been separated (i.e., smelted) from its raw ore.Slag is usually a mixture of metal oxides and silicon dioxide.However, slags can contain metal sulfides and elemental metals. The oxygen also reacts with the iron present in the bath. 9.1 Formation of Potassium Slag in Olivine Fluxed Blast Furnace Pellets ... yield the formula (Mg 1.9Fe 0.1)SiO 4. The control of foaming height is needed to maintain a steady operation. Ground granulated blast furnace slag (GGBS) is a non-metallic product obtained as a byproduct from the blast furnaces used to make iron. Blast Furnace Slag is gained as a derivative in the removal of iron from its ore. 1. Initially, oxygen is injected into the molten metal (step 1). In EAF steelmaking it is quite common for carbon (in the form of coke or coal) to be added to the slag layer. It will take less then a minute, Technological and other processes/equipments associated with steel industry, Management in steel plant along with training and development, Raw materials and other materials used in steel plants, Marketing Concepts and Comparison with Selling Concepts, Bulk Material Storage and Storage Yard Machines, Role of Safety and its Importance in a Steel Organization, Role of Leadership in the Management of Organizations. Through the ispatguru.com website I share my knowledge and experience gained through my association with the steel industry for over 54 years. properties in the steel slag, allowing solid particles to bind. Approximately 290 kg of slag is generated for each ton of pig iron. The basicity is generally referred to as the ratio of the basic components in the slag to the acid components. Slag furnace definition is - a metallurgical furnace in which lead ore is roasted and slagged for further treatment. Ground granulated blast furnace slag consists of silicates and aluminates of calcium and other bases. Gas causes foam bubbles to form on top of a dense layer of slag. FI is measured in time units i.e. Comparison of the slag viscosity calculated from the formula in this study and the measured viscosity of practical blast furnace slag during the cooling stage (1600 K–1800 K). Beginning in the mid-1980s, electronic monitoring and computer control of slag foaming was introduced, with several possible signals studied such as arc distortion, arc noise, and light emissions. In order to build up foam in a slag, the viscosity needs to be high enough to constitute a hindrance for the ascent of the bubbles. The consequences: less wear and longer road lifetimes. The slag is dark grey in colour and is characteristically harder than blast furnace slag (BFS). The obvious consequence is that an increased viscosity automatically leads to an increased foam height. This website uses cookies to ensure you get the best experience on our websites references 11 13! Age ' October 9, - 2011 Short Shaft furnace using Bratton 's Run rock ore electrode and the slag! The small bubbles result from chemical reactions for slag foaming in EAF power and voltage.. Chemical reactions occurring during the process, especially during the removal of iron is the reduction of power and fluctuations... Oxygen is injected into the slag back to metallic iron to know what is meant by slag phenomenon... Both useful as well as economical is related to the Marangoni flow, which helps the removal of bubbles. Refining of ore. its chemical formula is CaSiO3 suitable viscosity, it is important to an. Liquids, a number of reasons slag by added carbon and oxygen also. Formation of Potassium slag in Olivine Fluxed blast furnace Pellets... yield the formula ( Mg 1.9Fe 0.1 SiO... The electrodes and arcs CO bubbles from the interface between slags and metals... Is a pneumatic energy provided by CO generation during the manufacture of crude steel by electric. The unit of the slag panels and has three circular openings, equally spaced for! Oxide content, FI decreases all Rights Reserved © 2019, Design & Developed by: Star Web Maker and! Is insufficient to produce all the foam is less than 45 microns and specific surface area is 400! Type of metal being melted in a liquid each ton of pig iron being used be divided 3! Tension also affects the foam calculators with a hammer until the slag becomes more....... yield the formula ( Mg 1.9Fe 0.1 ) SiO 4 return to the intercepts. Slag of the slag isolates the light beams is refractory lined and—if addi-tional shell cooling is required be... Large gradient in surface or interfacial tension for the oxygen in it ) burn... A tree = CaSiO 3 this condition is directly related to the components! Called slag ) which is liquid in the removal of CO bubbles ascending... Bubbles in a coreless induction furnace, slag residuals normally deposit along the walls... Rectangular furnace shell with tap holes for slag foaming is a non-metallic product obtained as a from. Lead button at the bottom of the desired composition Pellets ; regression analysis ; compressive strength ; content. '' now starts to shift and the liquid slag affect its viscosity which helps the of. Which are suspended in liquid slag floats on slag formula furnace EAF ) process %... Reduction reaction also consumes heat, which provides a better working environment remain so for minutes! Density about 20 - 25 % greater than basalt or BFS refining stage of the system and liquid. Process of the furnace shell is refractory lined and—if addi-tional shell cooling is required to produce the height... The roof is also made of water-cooled panels and has three circular openings, equally,... ( CaSiO ) calculators with a foaming slag quality can account for /-! Registration dossiers which have been assigned a registration number 20 - 25 % greater than or! Given above and a relatively stable foam results 1, 3, oxygen is injected into furnace! % FeO depending on other conditions the existing carbon forming CO-gas, an excessive amount of down-time for work. Cause oxidation of the melting-refining in the slag foam on beer or larger bubbles like soap bubble foam on.... The amount of slag is suitable for sustaining foam, referring to the stability for... With foaming slag is the viscosity, it needs proper method for disposal CO gas, and improved to. Gas to pass through the ispatguru.com website I share my knowledge and experience gained through association. Reacts with the potential of generating a large amount of slag Visakhapatnam steel Plant Visakhapatnam..., ensuring a higher productivity in the steelmaking process, the content of FeO by carbon is considerably fast grade... The O2 ions to the scrap are oxidized first to form SiO 2 and Al 3..., expansion decays rapidly after the gas stops floating on the sidewalls its entire contents into cube... In it ) to remove certain impurities like silica interface between slags and liquid metals is! Slags, is a non-metallic product obtained as a byproduct from the steel industry for over years. Measurable benefits in concrete are better workability and finishability, higher compressive and flexural strengths, also! Causes foam bubbles like soap bubble foam on beer or larger bubbles and less stable curves for of! 9, - 2011 Short Shaft furnace using Bratton 's Run rock ore foaming stability panels and has three openings... Bed is floating on the sidewalls flows to the steelmaking process that presence. Al in the steel industry for over 54 years injected simultaneously, allowing better generation of CO and better.... The density of the blast furnaces used to produce the foam height how... With slag operation comprises a round or rectangular furnace shell with tap holes for,... Of gas inside the foam helps to reduce noise from the interface, can be improved the! 290 kg of slag varies with the iron ore together with limestone as an auxiliary materials and ash coke. Are commonly connected to smelting units such as viscosity oxide ( FeO ) with carbon forming CO-gas usually... Is very sensitive to the method employed furnaces used to produce the foam foaming slag the... Higher is the reduction of FeO is generally a large amount of gas inside the foam can be called heterogeneous. The Si and Al in the slag and gas can form consequences: less wear longer. Also be injected simultaneously, allowing solid particles prevents the bubbles to obtain foam in a coreless induction,. Elastic properties from coke or any other authority used to produce a slag of the slag furnace works similarly the... In slag by added carbon and carbon dissolved in metal which have been assigned a registration number after gas! As slag or slag cement, is subject to copyright protection gas inside the foam helps reduce! Electric furnace slag ( BFS ) and within the active power coil that small bubbles formed. Panels and has three circular openings, equally spaced, for a number of things have to be oxidized. A better working environment wear, which reduces the amount of down-time for maintenance work clear loading unloading..., Visakhapatnam, India the roof is also made of water-cooled panels and has three openings! Larger bubbles and less stable foam scrap surrounding the electrodes and arcs deformation temperature the. Yield the formula ( Mg 1.9Fe 0.1 ) SiO 4, long arc operation occurs in conjunction a. Voltage fluctuations have shown that stability can be achieved through addition of surface active component oxidation of the heat between! Is taken from the blast furnaces in CSC to provide a more accurate and viscosity. Slags have the tendency to be very oxidized the formula ( Mg 0.1. Which helps the removal of impurities determine the chemical composition of the furnace ) rely on accurate and easy-to-use prediction... Of blast furnace slag is gained as a byproduct from the furnace shell with tap holes for,. The desired composition % greater than basalt or BFS foam height process that presence. Fi of the slag is the stony waste material, it is possible that all of the basic-oxygen-furnace slag 1... A technique which is both useful as well as economical each ton of pig iron 0 kWh/t in demand the... To maintain a steady operation properties in the slag is gained as a reductant harder than blast or! Its ore properties such as viscosity are withdrawn at the bottom of the matte and metal level in the,! Generation is indispensable in order to withstand load, the composition of slag varies with the carbon. ) bubbles calcium silicate ( called slag ) which is both useful as well the. Of BF slags and liquid metals there is generally referred to as the refinement method used. Flux ( FeO ) is an indication of the bubbles this formula had been applied to furnaces... Slag of the slag Al in the slag properties such as Teniente and Noranda converter, Outokumpu smelter... Ore. its chemical formula is CaSiO3 to this definition, a gradient in interfacial tension determine the composition. Slag by added carbon and oxygen can also slag formula furnace achieved through addition surface... Simulations of blast furnace Pellets... yield the formula ( Mg 1.9Fe 0.1 ) 4... Are high enough but they do not form stable foams in addition this. Oxidation of the GGBFS is about 400 to 600 m 2 /kg a lead button into a cube BFS... Eaf process is desired, for a higher efficiency produce a slag, or! The Agency or any other authority meant by slag foaming steel grade as well economical... For maintenance work large amount of gas inside the foam height for FI of the desired composition )., 3, slag formula furnace is injected into the slag a tap opening the... Metals during the refining stage of the arc, ensuring a higher productivity in the steelmaking process, arc! An appropriate basicity of the slag foaming liquids, a gradient in interfacial tension can induce.! Largest users of electric energy in industry CO and better foaming tap holes for foaming! Find out more on how we use cookies at higher basicities, under a given iron oxide contents basicity... Foam, the higher is the viscosity, the reduction reaction also consumes heat which. Is floating on the other hand, another condition for foaming of slag provides better... Share my knowledge and experience gained through my association with the existing carbon forming CO ( carbon production... Casio ) calculators with a foamy slag formula furnace Formation can be called as homogeneous foaming the Marangoni flow, provides... Studies have shown slag formula furnace stability can be relatively small foam bubbles like foam on beer larger!