Papers by Keyword: Electric Arc Furnace Slag

Abstract: The possibility of producing iron and silicon-coagulant-flocculant for purification of waste water was shown. The electric steel melting slag JSC "OMK-Steel" has been used as the starting material, in which the content of iron oxide to 25.8% and silicon dioxide is 17.6%. The optimal parameters of slag hydrochloric opening were as follows: the modification time at T = 40 °C – 1 hour, the concentration of hydrochloric acid – 1.5 N, the ratio of the solid and liquid phases of S : L = 1 : 10. In these settings the concentration of hydrosilicic acid (for silicon) will be 1532 mg/l; the concentration of iron – 1250 mg/l has a lower concentration of silicic acid in the production of the solution with increasing temperature and time of exposure. This paper examined the chemical aspects of the process of obtaining the new iron-containing coagulant-flocculant based on electric furnace slag. The results can be used to produce coagulants and flocculants using industrial waste.

Abstract: Eutrophication as a result of uncontrolled phosphorus (P) concentration that is released in wastewater has emerged as a major problem nowadays. Treatment of P demands high costs specifically to its chemical and maintenance needs. A lot of efforts were undertaken to find the most economical material that can treat P such as Electric Arc Furnace Slag (EAFS), a by-product from steel industry and Limestone (LS), and a natural resource that can be easily obtained from sedimentary rock. Despite numerous study conducted previously, the mechanism of P removal between these two materials have not been explored yet in detail. Therefore, an experimental work had been designed to evaluate the performance of P removal mechanism between the EAFS and LS lab-scale filter systems which can offer the best removal in overall. In this study a column lab scale of vertical rock filters in 100 mm diameter × 400 mm height were constructed for both EAFS and LS filters. The observation period was conducted for 2.5 months utilizing synthetic phosphorus concentration of 25 mg/L as its initial concentration. Working condition of the experiment was adjusted at pH 4.5 to 7.5 under 26.8±0.64 °C. X-ray fluorescence (XRF) analysis was also performed in order to determine chemical composition of EAFS and LS media. Results revealed that EAFS showed a significant effect on the removal of P mechanism compared to the LS filter system. The highest removal of P for both filter systems were observed to achieve 90% (pH 5) in the EAFS compared to only 68% (pH 4.5) in the LS system. This may be associated with the dissolution of Ca, Fe and Al elements in the EAFS that promotes precipitation process and hence gave higher removal compared to the LS element (only Ca has the highest percentage = 91%). At lower pH (acidic) condition the soluble metal salts react with phosphate ion to form phosphate hydrolysis product thus promoting precipitation in the system. In conclusion, it is predicted that precipitation may occur within the filter systems predominantly in the EAFS filter as pH was change from acidic to alkaline (4.5 – 7.5) due to dissolved (Al³⁺, Ca²⁺, Fe³⁺) within the filter system. Nevertheless, it is recommended that future study should be carried out on the precipitates salts through X-ray diffraction (XRD) analysis so as the existence of phosphate and metal salts as a result of precipitation can be finally confirmed.

Abstract: The utilization of modified electric arc furnace slag (EAFS) was successfully carried out to remove reactive dyes (SSB-BRF) from aqueous solutions. Modified EAFS was prepared and characterized by BET surface area analyzer and FESEM. The result of FESEM micrograph shows that the structure of modified EAFS has similar structure to the flower-like porous hematite (α-Fe₂O₃) nanoarchitectures composed of ultra-thin nanoflakes. Batch studies were carried out to address various experimental parameters such as adsorbent amount and concentration of dye. In the batch system, the maximum SSB-BRF uptake capacities of modified and original EAFS adsorbent (at 300 ppm dye concentration) were 80.03 and 20.99 mgg⁻¹ respectively. In the batch system for different amount of slag, the maximum uptake capacities SSB-BRF of modified and original EAFS were 92.24 and 19.08 mgg^-1 (adsorption of 300 ppm of dye concentration onto 0.1 g of slag) respectively. The Langmuir models were able to describe the adsorption equilibrium. The results indicated that modified EAFS could be employed as an excellent and low-cost sorbent for removal of reactive dye from aqueous solution.

Abstract: 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.

Abstract: Electric arc furnace slag (EAF-S), coming from a steel productive plant in Italy, has been used as new source for geopolymers synthesis. The slag has been geopolymerized alone and with different content of metakaolin (MK) with the aim to investigate if EAF-S content plays a role in geopolymerization process. Mechanical properties results and microstructure analysis highlight that the optimum weight ratio MK/EAF-S to be used as starting materials is 40/60, 30/70, 20/80. Moreover EAF-S, when used with MK, directly participates in the formation of calcium-rich alumino-silicate gels.