scholarly journals The Influence of Slag Tapping Method on the Efficiency of Stabilization Treatment of Electric Arc Furnace Carbon Steel Slag (EAF-C)

Minerals ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 706 ◽  
Author(s):  
Davide Mombelli ◽  
Andrea Gruttadauria ◽  
Silvia Barella ◽  
Carlo Mapelli

Studies conducted over the past 10 years have demonstrated the technical suitability of the electric arc furnace slag as an alternative to natural stone in several applications. Steel slag can be profitably used as a road surface layer, for foundations and embankments, or for concrete aggregates. However, a strong limitation to their use is due to the presence of toxic metals (Ba, Cr, V, Mo, etc.) that can be released into the environment in particular conditions, especially for unbound products in which the slag can come into contact with water. Recent studies have investigated the role of chemical composition and microstructure of slag on toxic metal leaching, allowing for the design of suitable stabilization treatments for hindering such leaching. In this work, four batches of electric arc furnace carbon steel slag underwent a stabilization treatment and the obtained results were compared. In two batches, the stabilizer was added directly in the slag pot and the slag was cooled down in the same pot. The other two batches were stabilized during the downfall from slag door to slag pit. Several slag samples were collected before and after the stabilization treatment and were characterized by means of ED-XRF, XRD, and SEM analysis. Leaching tests were carried out in agreement with EN 12457-2 standard on 4 mm granulated slag, and the leachate concentration was compared with the current Italian limits listed in D.M. 3 August 2005 N. 201 and D.M. 5 April 2006 N. 186. The results clearly indicated that the cooling in the slag pot improved the efficiency of the stabilization treatment, leading to a complete transformation of the microstructure by a full development of homogeneous gehlenite matrix and a coarsening of Cr-spinels, assuring better toxic metal retention behavior. On the contrary, stabilization in the slag-pit was rapid and reduced the interaction between slag and stabilizer, leading only to partial transformation of larnite into gehlenite, and also reducing the coarsening of Cr-spinel. In addition, a layering effect was observed, resulting in an inhomogeneous product from top to bottom in terms of chemical composition, microstructure, and leaching behavior.

2016 ◽  
Vol 102 ◽  
pp. 810-821 ◽  
Author(s):  
D. Mombelli ◽  
C. Mapelli ◽  
S. Barella ◽  
C. Di Cecca ◽  
G. Le Saout ◽  
...  

2018 ◽  
Vol 7 (3.23) ◽  
pp. 1 ◽  
Author(s):  
Siti Zu Nurain Ahmad ◽  
Hamdan R ◽  
Wan Afnizan Wan Mohamed ◽  
N Othman ◽  
Nur Shaylinda Mohd Zin

Electric arc furnace (EAF) slag as filter media has been extensively used nowadays for wastewater treatment technology. Steel slag was produced as byproduct from steelmaking processes. However, different batches of steel slag production produce different composition. Thus, this study determined the chemical composition, pH value and points of zero charge (PZC) of two different samples of electric arc furnace (EAF) slag; high iron EAF slag (Slag HFe) and high calcium EAF slag (Slag HCa). The steel slag were characterized using X-ray Fluorescence Spectroscopy (XRF) analysis for the chemical composition, extraction with boiling water for pH value, and salt addition method for PZC. Slag HFe was mainly consisted of 38.2% ferric oxide and 20.4% calcium oxide, 10.20 pH value and pH 10.55 for PZC. While for Slag HCa, they were composed of 1.64% ferric oxide and 49.5% calcium oxide of pH value of 11.11 and pH 11.75 for PZC. Therefore, Slag HCa was considered as a more basic species compared to Slag HFe. 


Metals ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 1347 ◽  
Author(s):  
Pao Ter Teo ◽  
Siti Koriah Zakaria ◽  
Siti Zuliana Salleh ◽  
Mustaffa Ali Azhar Taib ◽  
Nurulakmal Mohd Sharif ◽  
...  

Steel slag is one of the most common waste products from the steelmaking industry. Conventional methods of slag disposal can cause negative impacts on humans and the environment. In this paper, the process of steel and steel slag production, physical and chemical properties, and potential options of slag recycling were reviewed. Since steel is mainly produced through an electric arc furnace (EAF) in Malaysia, most of the recycling options reviewed in this paper focused on EAF slag and the strengths and weaknesses of each recycle option were outlined. Based on the reports from previous studies, it was found that only a portion of EAF slag is recycled into more straightforward, but lower added value applications such as aggregates for the construction industry and filter/absorber for wastewater treatments. On the other hand, higher added value recycling options for EAF slag that are more complicated such as incorporated as raw material for Portland cement and ceramic building materials remain at the laboratory testing stage. The main hurdle preventing EAF slag from being incorporated as a raw material for higher added value industrial applications is its inconsistent chemical composition. The chemical composition of EAF slag can vary based on the scrap metal used for steel production. For this, mineral separation techniques can be introduced to classify the EAF slag base on its physical and chemical compositions. We concluded that future research on recycling EAF slag should focus on separation techniques that diversify the recycling options for EAF slag, thereby increasing the waste product’s recycling rate.


2021 ◽  
Vol 9 (2) ◽  
pp. 53-57
Author(s):  
Osama Daoud ◽  
Muntasir Ibrahim

This research paper focuses on the possibility of utilization of Giad electric arc furnace slag (GEAFS) as a partial replacement for coarse aggregates in concrete, without compromising on its workability and strength. The electric arc furnace slag is a waste product from the steel manufacturing which may be used as partial replacement of coarse aggregates in concrete. This paper presents an experimental study on fresh and hardened properties of concrete containing steel slag aggregates. Slump, as well as strength properties of concrete prepared with natural coarse aggregate, partially replaced by the GEAFS in different proportions varying from 25 %, 50 % and 75 %. The GEAFS concrete shows marginal decrease in slump for the further replacement. Compressive, split and Flexural strength of the GEAFS concrete have been increased for the GEAFS addition. Highest compressive, tensile and flexural strength have been achieved by the mix containing 50 % GEAFS coarse aggregates. Using of steel slag will result in decrease of waste landfilling, and improving environmental condition.  


2011 ◽  
Vol 287-290 ◽  
pp. 906-909 ◽  
Author(s):  
Zai Bo Li ◽  
San Yin Zhao ◽  
Xu Guang Zhao ◽  
Tu Sheng He

To realize the industrial application of online reconstruction technique of steel slag, a pilot-scale reconstruction research of steel slag (SS) with electric arc furnace slag (EAFS) and coal cinder (CC) and its mechanism were investigated. The results show that after reconstruction, the free-CaO content of reconstructed steel slag (RSS) is reduced. XRD analysis indicates that the reconstruction reaction can promote to create more active cementitious minerals (C2S, C3S, C6AF2 and C6A2F) in RSS. Composition adjusting materials formula composing of EAFS and CC at the ratio of 70:30 is optimum, which can meet the standard of the first grade steel slag powder according to Chinese National Standards GB/T 20491-2006.


2014 ◽  
Vol 279 ◽  
pp. 586-596 ◽  
Author(s):  
D. Mombelli ◽  
C. Mapelli ◽  
S. Barella ◽  
A. Gruttadauria ◽  
G. Le Saout ◽  
...  

Minerals ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 47
Author(s):  
Kathy Bru ◽  
Alain Seron ◽  
Agnieszka Morillon ◽  
David Algermissen ◽  
Catherine Lerouge ◽  
...  

This study investigates the potential to recover iron and chromium from a chromium-bearing carbon steel Electric Arc Furnace (EAF) slag. This slag contains indeed about 30 wt.% Fe and 2.5 wt.% Cr. However, the minerals are intergrown at small scale (<100 µm) and iron and chromium are mostly contained in spinel phases which makes the separation challenging. Several methods including Mössbauer spectroscopy, X-ray Diffraction, Scanning Electron Microscopy (SEM) and electron microprobe analysis were used in order to fully characterize the products obtained after a low-intensity magnetic separation of this carbon steel EAF slag, with the objective to define a pre-treatment process allowing the recovery of iron-rich particles and of a chromium-upgraded fraction. The results show that even if the magnetic separation seems to be not efficient in a first approach for producing an iron-rich/chromium-poor fraction, this fraction can be obtained by adding an attrition step which means that some separation mechanisms still occurred during the magnetic separation. However, it was not possible to produce a chromium-rich fraction. The main bottleneck for reaching a good separation is most probably the very fine liberation size of the iron and chromium bearing minerals.


2019 ◽  
Vol 19 (2) ◽  
pp. 21-32 ◽  
Author(s):  
Carmenlucia Santos Giordano Penteado ◽  
Beatriz Leão Evangelista ◽  
Gisleiva Cristina dos Santos Ferreira ◽  
Pedro Henrique Andrade Borges ◽  
Rosa Cristina Cecche Lintz

Abstract In this study the electric arc furnace slag was used as coarse natural aggregate substitute in concrete paving blocks production. The concrete mixture was defined by using weight proportions in the ratio of 1:2:3:0.51 (cement:sand:coarse aggregate:water) in order to obtain a compressive strength of 35 MPa. Four groups of concrete were prepared: a reference recipe and three others with the slag replacing the natural aggregate in the proportions of 25%, 50% and 75%. The compressive strength was not influenced by the slag content; however, it was influenced by the curing age, as the sample with 75% of slag addition had its compressive strength increased by 13.5% from 7 to 56 days. Water absorption presented a slightly reduction with slag addition. The results of compressive strength and water absorption met the Brazilian technical requirements, making the paving blocks suitable for use in light vehicle traffic. The results obtained in this study highlight the influence of the production process in the final quality of the steel slag, and the need of stablishing technical and environmental requirements to guide and promote the safe use of electric arc furnace slag in concrete.


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