Bf and bof slag generated in integrated mills but eaf slag is achieved in mini mills. Both bof and eaf slags are somewhat heavier than blast furnace slag and most quarried rock material. Its content in the metal is usually equal or less than 0. Steel slag material description user guidelines for waste. Slag formers are either charged with the scrap or blown into the furnace. High calcium lime ca source dolomitic lime ca, mg source preblended lime mixes met grade ca mg mix mgo carbon briquettes proslag mg and c source pig iron fe, mn to counter high ni, cu, cr scrap. The main chemical composition of the slag is shown in table 1.
Since then, that concept has been applied in a number of areas. In the case of japan, three types of slags, namely bf slag, bof slag, and eaf. Molten slag is generally placed into ground bays for cooling. Characterization of the eaf steel slag as aggregate for. In a similar fashion, slag foaming in the electric arc furnace eaf has not only. I prove by my own researches that the electric arc furnace slag isnt harmful to the nature especially the ground water and their physical aspects are similar to the natural rocks. As oxygen is blown into the furnace, the principal flux feo is generated. Fatigue behavior analysis of asphalt mixes containing. Prevent the liquid steel from absorbing hydrogen and nitrogen. Evaluation of electric arc furnaceprocessed steel slag for. In the second part of the trials bigger additions of demetallized slag into eaf charge were examined. Gle 110t sections include 3 hours of class time, mwf. In terms of chemical composition, the slag mainly consisted of oxides such as al2o3, cao. On average the production of one tonne of steel results in 200 kg eaf to 400 kg bfbof of coproducts.
Introduction slag is the glasslike byproduct left over after a desired metal has been separated i. The metallurgical slag is a normal building material in europe but not in hungary. Slag foaming in electric furnace steelmaking waseda. Influence of electric arc furnace eaf slag aggregate sizes. 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.
Electric arc furnace slag as coarse recycled aggregate for. The results show that the calcium leaching ratio from eaf slag at the constant temperature in the microwave field increases about 10% than that under the water bath at the same leaching time. The above properties make eaf slag a good candidate for use in many areas of. Influence of electric arc furnace eaf slag aggregate. Steel slag is a known byproduct produced during the conversion of iron ore or scrap iron to steel. It means that we can use slag to replace them to save our environment and to clear away the old slag dumps. Physical and chemical characteristics of blast furnace.
Disposal of such material requires large surfaces and it is rather unfavorable in economic terms. Therefore, the chemical composition of eaf slag depends significantly on the properties of the recycled steel. Attendance at one tutoring session with the classlinked tutor four times during the semester is required. In the case of steelmaking slag, the slag contains metal elements such as iron in oxide form. Blending with many other products such as granulated slag, fly ash and lime to form pavement material, skid resistant asphalt aggregate and unconfined construction fill. Online slag composition analysis for electric arc furnaces 3 measurement device to be installed on the furnace. Sustainability improvements in the concrete industry springerlink. It consists of oxidizing slag that is generated during oxidation refining, and reducing slag that is generated during reduction refining. As such, eaf slag has potential to cause dermal irritation and sensitization at sufficient dose, but no published study has characterized the potential for dermal effects associated with eaf slag. Tests on the soundness of the slag for use as aggregate in road construction were carried out in accordance with european standards. Ironmaking and steelmaking slags are inevitably generated as a byproduct from ironmaking and steelmaking processes. The metallurgical properties of the slag are strongly influenced by. Particularly the reuse as coarse aggregate for concrete production has been shown to.
The eaf steelmaking process is essentially a steel scrap recycling process. Electric arc furnace eaf slag is a byproduct of steel production in electric arc furnaces. Evaluation of electric arc furnaceprocessed steel slag. The first use of burners was for melting the scrap at. Chemical, mineralogical, and morphological properties of. The viscosity of the slag may vary from watery to crusty depending on the temperature and composition 8,9,10,11. It is now common for between 30 to 40% of the total energy input to the eaf to come from oxyfuel burners and oxygen lancing.
Arc furnaces used in research laboratories and by dentists may have a capacity of only a few. Both bof and eaf slags are somewhat heavier than blast furnace slag. The major categories of steel slag, based on its raw materials and production process includes basic oxygen. Other components of blast furnace slag include alumina alsub2 o 3 and magnesium oxide mgo, as well as a small amount of sulfur s, while steelmaking slag contains iron oxide feo and magnesium oxide mgo. Steel slag material description user guidelines for. Groundgranulated blastfurnace slag ggbs or ggbfs is obtained by quenching molten iron slag a byproduct of iron and steelmaking from a blast furnace in water or steam, to produce a glassy, granular product that is then dried and ground into a fine powder. Supplement 5 is a novel attempt to quantify the real viscosity and thereby the. In addition, the electrical and material efficiency of the electric arc furnace eaf can considerably be improved by a good slag practice. The effect of foamy slag in electric arc furnaces on electric. Virtually all steel is now made in integrated steel plants using a version of the basic.
For example, portion of the separated slag, that does not have an increased content of metallic components, with regard to its properties, can be applied in the construction industry. Slag foaming in electric furnace steelmaking waseda university. The slag occurs as a molten liquid melt and is a complex solution of silicates and oxides that solidifies upon cooling. A study of eaf highchromium stainless steelmaking slags. Model studies on the effects of composition differences of. Grain size effect in elution test of electric arc furnace slag mdpi. The effect of microwavesupported leaching of electric arc furnace eaf slag by ammonium salts was investigated to improve calcium leaching ratio for co2 mineral sequestration process. The first stage of the scrapbased steel industry production generates eaf slag eafs and a second stage is performed to refine the molten steel. The aim of aso siderurgica in developing the slag rec system for the treatment of eaf slag is. Approximately 21 million tons of steel industry slag are produced each year in the united states, and many productive commercial uses of slag have been developed e. This carbon reacts with iron oxide in the slag, creating. Among the steelmaking slags, eaf slag is worth mentioning, as its application as aggregate for concrete is gaining increasing attention.
Characterization of ladle furnace slag from carbon steel. On the other bof slag and electric arc furnace eaf slags are the two most commonly used slags in asphalt mixes. Electric arc furnace slag eaf or steel furnace slag produced when scrap metal and fluxes are oxidized by the use of an electric current. In the second method, slags are generated in the scrapbased steel industry. Thermodynamic calculations predicting mgo saturated eaf slag.
This provides a novel and promising way for the economic co2 sequestration. They found that stainless eaf slag mainly contains merwinite ca3mgsio42, bredigite ca14mg2sio48, akermanite ca2mgsi2o7 and as minor. Microwavesupported leaching of electric arc furnace eaf. The measured foaming volumes are dependent on slag composition and test temperature. Mno contents in the eaf slag range from 2 to 9 wt% 10, 11. Main solid coproducts by steelmaking routes2 an average value is shown for the eaf route see figure 1, as eaf plants often use a mix of dri and recycled steel feeds. Euroslag, which is an international organization dealing with iron and steel slag matters, has estimated that about 25. Approximately 110 kg of slag is generated for each ton of converter steel. A good slag practice is essential for production of a highquality stainless steel. Industrial experiments with recycling of demetallized eaf slag into eaf charge showed the additions of demetallized slag had no negative effects on smelting process parameters, on composition and cleanness of produced steel. Conversations to composition students the support they need to succeed in gle 110 and move on to succeed in gle 120, composition ii. Electric arc furnaces are the largest users of electric energy in industry.
Mineralogical composition of eaf slag and stabilised aod slag. Tetronics testwork, and the scaleup potential of aseas dc arc furnace. Page 2 chemical and mineralogic composition chemical analyses of blastfurnace slags usually show that the four major oxides lime, magnesia, silica and alumina make up about 95% of the total. Use of steel slag in subgrade applications purdue epubs. However, slags can contain metal sulfides and elemental metals. However, because slag contains heavy metals at concentrations that are higher than in most soil, questions have been raised regarding the need to evaluate the potential human health and environmental. The slag balance now starts to shift and the slag becomes more liquid. 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. Microstructural and mechanical characterization of electric arc furnace eaf slag for use as abrasive grit material. The eaf slag is an ionic solution that floats on top of the steel. A comparative assessment of the mechanical properties of concrete containing electric arc furnace eaf oxidizing slag and granulated blast furnace gbf slag was performed. The use of the lf slag in further applications requires. Slag is the glasslike byproduct left over after a desired metal has been separated i. Thermodynamic calculations predicting mgo saturated eaf.
The metallurgical properties of the slag are strongly influenced by its hightemperature microstructure. Electric arc furnace slag electric arc furnace slag is generated when iron scrap is melted and refined. The steel slag used in this study is a scrap metal based steel slag produced from the electric arc furnace process. Bbof slag bofs is produced in the steelmaking process by using the molten iron coming from the bf. Electric arc furnace eaf slag, a byproduct of steelmaking recovered after the oxidizing process, is useful when employed as aggregate in hydraulic concrete and bituminous mixtures. Characterization of the eaf steel slag as aggregate for use. The samples of slag were oven dried at 105 1 c to constant weight. Slag is usually a mixture of metal oxides and silicon dioxide. The aim of aso siderurgica in developing the slagrec system for the treatment of eaf slag is. The goal was to investigate the effects of the substitution of eaf oxidizing slag and gbf slag for cement, in order to examine the possibility of using eaf oxidizing slag. Foamy slags are widely used in eaf steel production because the use of these slags result in energy savings, productivity improvements, and enhanced refractory service life. 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.
N2 in order to understand the effect of slag composition on foaming in an eaf, slag foaming was quantitatively studied for caosio2feo slags at temperatures ranging from 1,250 to 1,400c. In the case of japan, three types of slags, namely bf slag, bof slag, and eaf slag are mainly produced, which amount is shown in figure. Groundgranulated blast furnace slag is highly cementitious and high in csh calcium silicate hydrates which is a strength enhancing. Thermophysical properties of slags for process control. Journal of biomimetics, biomaterials and biomedical engineering materials science. According to previous studies, about 70% of the total production of bf slag has been used as a replacement for portland cement due to its numerous advantages, e.
Several studies have tried to demonstrate its suitability in civil engineering application, such as in bituminous mixtures and cementbased materials, due to its good physical, chemical and mineralogical properties. The chemical composition of a slag varies considerably depending on the composition of the raw materials in the iron production process. In the case of steelmaking slag, the slag contains metal elements such as iron in oxide form, however because the refining time is short and the amount of limestone contained is large, a portion. Properties and uses of iron and steel slag mf 1826 national slag association. The effect of foamy slag in electric arc furnaces on. The primary components of iron and steel slag are limestone cao and silica sio 2. The main byproducts of the steel industry, blast furnace bf slag and steelmaking sm slag, can partially replace cement in concrete because of its potential hydraulicity 1,2,4,5,6,7,8,9. Physical and chemical characteristics of blast furnace, basic. This is where the application of prebaked graphite electrodes in a dc arc furnace came about.
Apart from that, aluminium oxide al 2o 3, manganese. Elrefaie3 abstract mass and energy balance equations are applied on top blowing bof and eaf steelmaking processes to detect the energy profile of production one ton steel by both processes. Main components of the slags are cao, sio 2, al 2 o 3, mgo, and iron oxides, and the compositions of slags depend on the process. The first use of burners was for melting the scrap at the slag door where arc heating was fairly inefficient.
Electric arc furnace eaf steel slag is alkaline ph of 1112 and contains metals that are known dermal sensitizers, most notably chromium and nickel. Eaf slag has a chemical composition similar to that of bof slag refer to table 1. This book examines stateoftheart techniques for using recycled materials for structural concrete. The major categories of steel slag, based on its raw materials and production process includes basic oxygen furnace bof slag and electric arc furnace eaf slag. Silicate and aluminate impurities from the ore and coke are combined in the blast furnace with a flux which lowers the viscosity of the slag. The effect of foamy slag in electric arc furnaces on electric energy consumption abstract in electric arc furnace steelmaking units, the essential parameters that considered important are reducing price, increasing production and decreasing environmental pollution. 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. Converter slag in the same way as aircooled blast furnace slag, converter slag is cooled slowly by natural cooling and water. Steel slag, a byproduct of steel making, is produced during the separation of the molten steel from impurities in steelmaking furnaces.
This paper will define the slag compositions required to obtain and control optimum foamy slag. In terms of chemical composition, it was found that the eaf slag primarily consists of iron oxide feo and fe 3o 4, calcium oxide cao and silicon dioxide sio 2. Structural composition of slag was the same as the one found in eaf heats slags produced without demetallized slag additions. Several studies have tried to demonstrate its suitability in civil engineering application, such as in. Today, one of the important indicators of sustainable steelmaking is quantity of slag production and its. Steelmaking slag consists of converter slag that is generated by converter and electric arc furnace slag that is generated during the electric arc furnace steelmaking process that uses steelscrap as the raw material. The annual output of steel slag in iran is more than 3 million tons which most of them are disposed. In addition to it, quantity of charged lime was proportionaly decreased. Comparing properties of concrete containing electric arc. This is accomplished through the precipitation of magnesium wustite particles in the slag at the operating temperature. Pdf this study aims to characterize and investigate properties of electric arc furnace eaf steel slag waste to ensure its compatibility and. Characterization of the eaf steel slag as aggregate for use in road construction tahir sofilic1, ana mladenovic2, una sofilic3 1cmc sisak d. Oxyfuel burners are currently standard equipment on eafs. Foamy slag requires the control of slag viscosity to sustain gas bubbles during processing.
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