Slag is usually a mixture of metal oxides and silicon dioxide. A suitable ladle flux must provide the following properties1. Control of gas bubbles and slag layer in a ladle furnace by. A thermodynamic and kinetic model of reoxidation and. The slag balance now starts to shift and the slag becomes more liquid. Chemical stabilization features of ladle furnace slag in ferrous. This system is specially designed to remove slag with phosphorus to make the steel clean. Desulphurization of steel at ladle furnace depends on temperature, amount of oxygen and sulphur in the steel, but mainly on chemical composition and physical properties of slag. The difference in chemical composition results in different mineral composition. The composition of furnace and ladle slag is often very complex. In the present paper, the effect of top slag composition, weight of carry over slag, optical basicity. Online slag composition analysis for electric arc furnaces. Research article characterization of ladle furnace slag from carbon steel. Fumes formed during the operation are extracted through the cover.
The developed model was useful for optimizing the operation of a ladle furnace. Then the bath is refined in a vacuum chamber where it continues to be mixed by argon blown in at the bottom. The chemical composition of ladle slag is significantly different from that of steel furnace slag in that the former has a very low feo content, a higher al 2 o 3 content. The use of the lf slag in further applications requires.
A new technique is presented to recycle ladle slag within the electric arc furnace through the injection system. The chemical composition of ladle furnace slag samples was investigated by means of a several different analytical methods. Figure 181 presents a diagram of the general flow and production of different slags in a modern steel plant. Partial substitution of cement by lfs in amounts of 20% by weight has no negative effects. Surface area properties have shown that the lf slag is a mesoporous material. Use of alkilled ladle furnace slag in sikilled steel process to reduce lime consumption, improve. Secondary refining american iron and steel institute. Ladle furnace reducing slag is a common byproduct in steelmaking of carbon and low alloy steels. Melting techniques type and size of melting furnaces, slag composition, condition, and quantity, temperature of melt, melting period. Steel slag material description user guidelines for waste. Vacuum refining influences not only the chemical composition of the metal, but also partly changes the composition of slag. Ladle furnace slag produced during the production of tmt grade steel at tsl, jamshedpur was used as base material for this study. The lf slag is a byproduct from further refining molten steel after coming out of a basic oxygen furnace bof or an electric arc furnace eaf. Control of gas bubbles and slag layer in a ladle furnace by electromagnetic stirring.
Ladle furnace slag characterization through hyperspectral. The module is primarily designed for application to steelmaking and steel re. Chemical, mineralogical, and morphological properties of. During this operation ferroalloys for control of the steel composition are added to the ladle. The refining slag is a new type steel casting auxiliary materials to meet the requirements for producing low sulphur steel. Treatment of lf slag to prevent powdering during cooling doiserbia. Effect of highalumina ladle furnace slag as cement. Different positions of the porous plug have been studied. Advances in molten slags, fluxes, and salts proceedings of the 10th international conference on molten slags, fluxes, and salts 2016. Secondary refining for purposes of this article, secondary refining or secondary metallurgy is defined as any post steelmaking process performed at a separate station prior to casting and hot metal desulfurizaion. Typically a transfer ladle will be used to transfer molten metal from a primary melting furnace to either a holding furnace or an autopour unit.
It was concluded that limes, an interface for thermocalc, is a useful tool for slag steel equilibrium calculations. Slag, steel, ladle and nonmetallic inclusions equilibria. Cement and concrete mineral admixtures concentrates mostly on natural pozzolans, fly ashes, ground granulated blast furnace slag, silica fume and limestone powder, namely the most commonly used mineral admixtures. Refining in the ladle furnace lasts between 40 minutes and 1 hour. Ladles are normally rated by their working capacity rather. On their basis researchers analysed the process of desulphurisation of steel at the ladle furnace workstation. However, it is difficult to maintain effective stirring currently in use. Methods of alloying in furnace or ladle, special injection methods, such as wire injection, in stream or in the mold treatments, intensifiers of dissolution by mixing. Also, certain metallurgical reactions, for reasons of equipment design and.
Jan 17, 2010 at this stage the slag usually contains a high iron oxide content cvs makina lf training d. Feedstock primary steelmaking furnace transfer ladle. A mathematical kinetic model to predict the trajectory of chemical compositions of the molten steel, slag, and inclusions in the ladle metallurgy furnace was presented in a recent study. A way to reduce environmental impact of ladle furnace slag. The dc plasma ladle furnace operates in the same way as the conventional ladle furnace, but with following differences. Advances in molten slags, fluxes, and salts proceedings. Slag substitution as a cementing material in concrete mdpi. Slag formation during the steel refining process in a ladle.
Refining slag used in outof furnace metal processing units, due to significant content in it of the unstable phasedicalcium silicate, is prone to decay due to its polymorphous transformations, accompanied by an increase in the volume of the crystal lattice. However, slags can contain metal sulfides and elemental metals. Slag modeling for effective desulphurization in ladle. Ladle furnace slag is produced through the addition of lime cao, and dolomitic limestone cao. Significant influence for steel desulphurization has content of easily reducible oxides in slag. A study of slagsteelinclusion interaction during ladle. Necessary requirement for effective desulphurization is also minimum amount of easy reducible oxides in the slag. Slag entrainment or carryover from furnace to ladle, a key to clean steel, should be. Missouri university of science and technology scholars mine. Introduction secondary steelmaking ladle operations handling basic slags uses magnesiacarbon refractories for the slagline lining to withstand the process chemistry and temperature 1, 2. Amount % cao % mgo % al2o3 lime 700 100 dolomite 500 60 40 caaluminate 500 45 55 al 100% 340 assumptions. Dissolution behavior of main minerals in hydrothermal leaching process of lf refining spent slag. Evaluation of inclusion composition during the ladle refining have revealed that the majority of the inclusions belonged to the system al2o3caomgosio2 and. Owing to our vast industry experience and expertise, we have been able to offer ladle refining furnaces.
Mainly used for ladle permanent layer and ladle bottom. The resulting byproduct, ladle furnace slag, contains high concentrations of calcium oxide. Tracking inclusions during ladle refining using a kinetic. Online slag composition analysis for electric arc furnaces 3 measurement device to be installed on the furnace. A new method for determining chemical composition of refining slag. This slag cannot be stabilized because of its selfdisintegrating properties 1. This process produces slag with only small variations in composition and properties. Effect of slag composition on desulfurization and inclusion modification during ladle furnace refining volume 111 issue 4 xin hao, xinhua wang, wanjun wang. Chemical, thermal and mechanical homogenization of both slag and steel during the ladle furnace process depends on the design of the gas injection system in gas bottom stirred ladles. Fix ladle refining furnaces, electrotherm india limited. One experimental trial was made to simulate ladle steelslag and steelinclusion reactions using an induction furnace to simulate deoxidation and slag addition. The steel slag produced during the primary stage of steel production is referred to as furnace slag or tap slag. Fix ladle refining furnaces, electrotherm india limited id.
The lf slag characterization in this paper has been performed using the following analytical methods. The compact design guarantees minimum space requirement while offering easy access to the roof and for electrode replacement. Behavior of self compacting concrete containing ladle furnace. Ladle furnace slag in construction journal of materials in. Temperature measurements on ladles in an industrial environment were carried out. Density and electrical conductivity of synthetic slags added. The lf stand is also equipped with an addition hopper mounted on the cover and a lance for injection of desulfurizing agents. 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 byproducts from melting and reactions with refractory linings. Properties of top slag are very important for desulphurization in ladle furnace lf refining. In this work, a method to analyze spectral reflectance of ladle furnace slag samples to estimate their composition is proposed. Planning and construction of the system hardware will already be focused on low maintenance requirements to ensure the technical and economic feasibility of the system and its broad applicability in eaf steel industry. The potential of ladle slag and electric arc furnace slag use in.
Physical system the ladle system simulated in this paper is shown in figure 2. Mechanical, physical and environmental properties have been evaluated. Pdf desulphurization characteristics of ladle furnace slags. The transient hot wire method was verified for thermal conductivity measurements on metallurgical slags and applied to ladle slag measurements. Slag is the glasslike byproduct left over after a desired metal has been separated i. To test the reliability of an available computational thermodynamic computer program, the first sub project was done. Refining slag for the lf refining furnaces rongsheng. Characteristics and cementitious properties of ladle slag. Corrosion mechanism of mgocmac ladle brick with high.
Others such as metakaolin, rice husk ash, expanded clays and shales are also discussed. Cao, sio 2, al 2 o 3, mgo, feo, mno, cr 2 o 3, p 2 o 5, tio 2, k 2 o and na 2 o. Download table chemical composition of the lf slag. Arc furnaces used in research laboratories and by dentists may have a capacity of only a few. Control of slag and insoluble buildup in ladles, melting. It can be melted into liquid slag under the heating treatment of electric arc.
In the present thesis a study on the thermal state of steelmaking ladles was undertaken. The carrying out of metallurgical reactions in the ladle is a common practice in practically all steelmaking shops, because it is costefficient to operate the primary furnace as a highspeed melter and to adjust the final chemical composition and temperature of the steel after tapping. This article provides results of studying the effect slag phase composition on chemical breakdown of a lfu. Ladle furnace slag lfs is a byproduct of a steel plant. In order to order to prevent the primary furnace slag from.
The manufacturing processes and chemical composition of each fiber class varies depending on their specific end use. Two different conditions of ladle treatment were simulated in regard to alumina and silica content in a basic slag. The oxidized slag containing 12 to 16% of fe is poured into a cast iron slag pot after the tapping and is disposed of in a slag yard. Cement and concrete mineral admixtures crc press book. A method of making a steel with low carbon less than 0. An electric arc furnace eaf is a furnace that heats charged material by means of an electric arc industrial arc furnaces range in size from small units of approximately one ton capacity used in foundries for producing cast iron products up to about 400 ton units used for secondary steelmaking.
The output of bar batches of all five size groups is analyzed for the content of nonmetallic inclusions according to state standard gost 80178 and the astm e45 standard method a. The ladle bottom has a porous refractory plug, which is connected to the argon supply pipe at the ladle furnace stand. The navys report manmade vitreous fibers, discusses three principal classes of manufactured vitreous fibers mvf. The dilution of the chemical species contained in the slag and their combination with the species featuring the eaf slag afford a double advantage. How to calculate a slag composition in a ladle using a massbalance approach consider the following additions to a ladle.
Huanyu he 1,2,3, weiwei hou 1,2,3, hongling liu 1,2,3, yang li 1,2,3. A kinetic model to predict the compositions of metal, slag. Samples of refining slag and metal were taken to analyse their chemical composition. Research article characterization of ladle furnace slag. Effect of refining slag phase composition on ladle furnace. Fullline secondary metallurgy solutions primetals technologies. Effect of ladle furnace slag composition in simn killed steel transient inclusion changes. The aim of the work presented in this contribution was to study the possibilities of eaf slag recycling into the refining remelting process in eaf and to recognize all possible positives and negatives of the recycling. Its raw materials are fused by the eaf, making this products with 90% 7al2o312cao calcium aluminate contents. At this stage the slag usually contains a high iron oxide content cvs makina lf training d.
Process metallurgy module for steel and slag thermocalc. The working layer of a ladle furnace unit lfu lining made from periclasegraphite refractory is most strongly subjected to the effect of corrosion factors that concern thermal, mechanical, and chemical action. The model considered the following chemical processes. For example, the regulatory documents regulate amount of converter slag in the ladle not more than 5. Dec 11, 2017 refractory materials common types of ladle refractories. A wide variety of slag ladle options are available to you, such as stainless steel. The strongest destructive effect on a lining is the chemical factor. The properties of a series of synthetic slag melts for steel refining in the ladlefurnace unit are determined in the range 14301645c. It is known that this kind of disintegration is driven by the presence of dicalcium. Characterization of ladle furnace slag from carbon steel. Since the cement content was kept constant at 350 kgm 3 and the fraction of the fine aggregate lower than 125.
Usually it has three different function types, for example, casting ladle, transfer ladle, treatment ladle. Steel production technology metallurgy for dummies. Dissolution behavior of main minerals in hydrothermal. Refining slag, ladle furnace refining slag, steel slag. This method does not require sample preprocessing and is based on a regression algorithm that mathematically maps the spectral reflectance of the slag with its actual composition with errors lower than 10%. As oxygen is blown into the furnace, the principal flux feo is generated. Key laboratory for ferrous metallurgy and resources utilization of ministry of education, wuhan university of science and technology, wuhan, hubei 430081, china 2. The changes in the inclusions calculated using the kinetic model were in good agreement with those predicted by the phase stability diagram.
Process metallurgy module for steel and slag the process metallurgy module is a calculator within thermocalc that makes it easy to set up calculations for steel and slag. Ladle furnace slag lfs is a nonuniform byproduct, and can be highalumina or highsilica slag. The chemical reactions occurring during the removal of impurities determine the chemical composition of the basicoxygen furnace slag 1, 3, 5. Characterization of ladle furnace slag from carbon steel production as a potential. Highalumina lfs has a better hydraulic reaction in mortars than highsilica lfs. Ladle furnace arrangements include single stations with fixedswiveling gantries or with ladle carsturrets and also twin stations two roofs with one swiveling electrode gantry. Paper open access major determinant of service life in. Chemical composition of the ladle furnace slag has been determined using. The results from the chemical analysis show that the approximate order of abundance of major components in ladle furnace slag is as follows. The steel is tapped to the ladle through a taphole by tilting the furnace. The average steel holding time in the ladle was 100 min. Figure 43 steps of ladle furnace process 65 figure 44 steps of trimming station process 66 figure 45 schematic secondary metallurgy process to show the time of samples.
This work investigates the effect of slag composition in steel slag and steelinclusion reaction kinetics in siliconmanganese killed steels by using factsage macros to simulate and predict inclusion composition and morphology changes during ladle treatment. Getting into cracks of the furnace lining, the slag can cause its destruction. The slag generated from a steelmaking cycle is later processed, and the final product after processing is referred to as basicoxygen furnace slag bof slag. In order to make a complete characterization of ladle furnace slag lf slag, lfs, as nonhazardous industrial waste, and to solve its permanent disposal andor recovery, bearing in mind both the. So as to achieve the purpose of refining steel liquid, thermal insulation and so on. Effect of ladle furnace slag composition in simn killed. Role of slag in the steel refining process in the ladle. In order to meet these requirements, some prefused materials have been used in ladle furnace.
Use of refining slag during the refining process of the lf furnace, the ladle is injected with a mixed slag prepared with a special ratio. Study of lf slag composition and its correlation with the. After air cooling and weathering over several days, this material is completely ground into fine white particles. These different types are referred to as furnace or tap slag, raker slag, synthetic or ladle slags, and pit or cleanout slag. Desulphurization characteristics of ladle furnace slags of a low sulphur steel article pdf available in canadian metallurgical quarterly 464. A promising type of steel slag for applications is the ladle furnace lf slag, which is also known as the basic slag, the reducing slag, the white slag, and the secondary refining slag. Analysis of refining processes in steel ladle treatment. Slag formers are either charged with the scrap or blown into the furnace.
While slags are generally used to remove waste in metal smelting, they can also serve other purposes, such as assisting in the temperature control of. This is a consequence of residual metal in the slag. Due to their mineral composition these industrial byproducts should be recycled and reused, not only for the purpose of reducing waste in the. No furnace slag was carried over into the ladle the recovery of al in the steel was 25%.