Occurrence and Leaching Behavior of Chromium in Synthetic Stainless Steel Slag Containing FetO

Stainless steel slag has been applied to other silicate materials due to its CaO-SiO2-based system. This is done to improve the utilization rate of stainless steel slag and apply it more safely. This paper investigated the occurrence of chromium in synthetic stainless steel slag containing FetO and its leaching behavior. The phase composition of the equilibrium reaction was calculated by FactSage 7.3 Equlib module. XRD, SEM-EDS and IPP 6.0 were used to investigate the phase compositions, microstructure and count the size of spinel crystals. The results indicate that the increase of Fe2O3 content can promote the precipitation of spinel phases and effectively inhibit the formation and precipitation of α-C2S in a CaO-SiO2-MgO-Cr2O3-Al2O3-FeO system. Fe2O3 contents increased from 2 wt% to 12 wt%, and the crystal size increased from 4.01 μm to 6.06 μm, with a growing rate of 51.12%. The results of SEM line scanning show the Cr-rich center and Fe-rich edge structure of the spinel phase. Comparing the TRGS 613 standard with the HJ/T 299-2007 standard, the leaching of Cr6+ in the FetO samples is far lower than the standards’ limit, and the minimum concentration is 0.00791 mg/L in 12 wt% Fe2O3 samples.

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Analysis on the stability of chromium in mineral phases in stainless steel slag

Metallurgical Research & Technology ◽

10.1051/metal/2017071 ◽

2017 ◽

Vol 115 (1) ◽

pp. 114 ◽

Cited By ~ 11

Author(s):

Long-hu Cao ◽

Cheng-jun Liu ◽

Qing Zhao ◽

Mao-fa Jiang

Keyword(s):

Aqueous Solution ◽

Stainless Steel ◽

Spinel Phase ◽

Steel Slag ◽

Dicalcium Silicate ◽

Limiting Factor ◽

Leaching Test ◽

Stainless Steel Slag ◽

Mineral Phases ◽

The Stability

Stainless steel slag from high alloy steel is hardly used in the construction industry. The chromium leaching in unstable phase is the limiting factor for the application in the slag. The aim of this study is to investigate the stability of mineral phases in stainless steel slag. In this work, the mineral phases were firstly confirmed through experimental results by SEM-EDS and XRD. Thermodynamic calculation and leaching test were adopted to characterize the theoretical stability of mineral phases in aqueous solution. The results showed that the main phases in the stainless steel slag were spinel, melilite [solid solution of gehlenite (Ca2Al2SiO7) and akermanite (Ca2MgSi2O7)], dicalcium silicate, merwinite and periclase phases. It can be concluded that the minerals behave differently when dissolving in aqueous solution and the dissolution of dicalcium silicate (Ca2SiO4), merwinite (Ca3MgSi2O8), akermanite (Ca2MgSi2O7) and periclase phase could be generally higher, especially at lower pH values. In addition, the solubility of chromium in the spinel phase is considered low. The leaching test demonstrated that the formation of spinel phase can limit the leaching of chromium and the chromium existing in the silicate and periclase phases can facilitate the chromium leaching.

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Effect of binary basicity on chromium occurrence in stainless steel slag

Journal of Mining and Metallurgy Section B Metallurgy ◽

10.2298/jmmb210304043z ◽

2021 ◽

pp. 43-43

Author(s):

Q. Zeng ◽

J.-L. Li ◽

G.-J. Ma ◽

H.-Y. Zhu

Keyword(s):

Stainless Steel ◽

Steel Slag ◽

Calcium Content ◽

Synthetic Slag ◽

Leaching Behavior ◽

Stainless Steel Slag ◽

Comprehensive Utilization ◽

Precipitation Occurrence ◽

The Relationship ◽

Lower Basicity

Comprehensive utilization of stainless-steel slag (SSS) is restrained due to the risk of Cr6+ leaching. Based on the studying the microstructure of synthetic slag (SS) containing Cr2O3with XRD, SEM-EDS?and Image pro, the effect of binary basicity on the chromium occurrence in SSS was investigated. The results indicated that the binary basicity had a significant impact on the properties of spinel crystals. There was a positive correlation between the calcium content in spinel crystals and the SS basicity. The size of spinel crystals varied from large to small and the precipitation occurrence changed with the basicity increase. Furthermore, the chromium occurrences changed with basicity. The chromium was produced in spinel crystals at lower basicity, but as the basicity increased to 3.0, the chromium precipitated as calcium chromate. In view of the relationship between the chromium leaching behavior and its occurrence, increasing basicity raised the Cr6+ leaching.

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Effect of Basicity on Precipitation of Spinel Crystals in a CaO-SiO2-MgO-Cr2O3-FeO System

High Temperature Materials and Processes ◽

10.1515/htmp-2019-0043 ◽

2019 ◽

Vol 38 (2019) ◽

pp. 867-872

Author(s):

Jianli Li ◽

Qiang Zeng ◽

Qiqiang Mou ◽

Yue Yu

Keyword(s):

Crystal Size ◽

Solid Phase ◽

Spinel Phase ◽

Steel Slag ◽

Solid Particles ◽

Particle Diffusion ◽

Spinel Crystal ◽

Stainless Steel Slag ◽

Comprehensive Utilization ◽

Key Factor

AbstractThe comprehensive utilization of stainless steel slag is one of major problems to be solved at “green steelworks”. Precipitation of spinel crystals can effectively detoxify residue. The effect of basicity defined by ω(CaO)/ ω(SiO2) ratio on precipitation of spinel crystals in a CaO-SiO2-MgO-Cr2O3-8 wt% FeO system has been determined with such tools as FactSage 7.1, SEM-EDS, IPP 6.0 and XRD. The FactSage 7.1 results showed that the rate of spinel phase enrichment with chromium was about 98% for the system basicity less than 1.4 and about 78% above this value. The precipitation of solid particles in solution appeared to be significantly influenced by basicity. With its increase the solid phase grew, the liquid one reduced, the particle diffusion was limited, and the growth of spinel crystals was inhibited. The spinel crystal size increased rapidly with decrease of basicity. When basicity increased from 0.6 up to 1.0, the crystal size decreased sharply from 12.30 μm down to 6.22 μm, and the reduction constituted as much as 49.43%. When basicity increased from 1.0 up to 2.2, the spinel crystal size moderately decreased from 6.22 μm down to 4.47 μm. Therefore, reduction of basicity is conducive to spinel crystal enrichment with chromium what appears to be a key factor to control basicity at detoxification of the chromium-containing steel slag.

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Physicochemical property and chromium leaching behavior in different environments of glass ceramics prepared from AOD stainless steel slag

Journal of Alloys and Compounds ◽

10.1016/j.jallcom.2019.07.065 ◽

2019 ◽

Vol 805 ◽

pp. 1106-1116 ◽

Cited By ~ 9

Author(s):

Shuai Zhang ◽

Yanling Zhang ◽

Zhenmin Qu

Keyword(s):

Stainless Steel ◽

Physicochemical Property ◽

Steel Slag ◽

Glass Ceramics ◽

Leaching Behavior ◽

Stainless Steel Slag

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High-capacity adsorbents from stainless steel slag for the control of dye pollutants in water

Environmental Science and Pollution Research ◽

10.1007/s11356-020-12174-0 ◽

2021 ◽

Author(s):

Lorenzo Plaza ◽

Marta Castellote ◽

Roman Nevshupa ◽

Eva Jimenez-Relinque

Keyword(s):

Stainless Steel ◽

Steel Slag ◽

High Capacity ◽

Stainless Steel Slag ◽

Dye Pollutants

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Experimental Study on Precipitation Behavior of Spinels in Stainless Steel-Making Slag under Heating Treatment

Processes ◽

10.3390/pr7080487 ◽

2019 ◽

Vol 7 (8) ◽

pp. 487 ◽

Cited By ~ 5

Author(s):

Jianli Li ◽

Qiqiang Mou ◽

Qiang Zeng ◽

Yue Yu

Keyword(s):

Particle Size ◽

Stainless Steel ◽

Steel Slag ◽

Calcium Content ◽

Heating Time ◽

X Ray Diffraction ◽

Stainless Steel Slag ◽

Steel Making ◽

Heating Treatment ◽

The Stability

The stability of chromium in stainless steel slag has a positive correlation with spinel particle size and a negative correlation with the calcium content of the spinel. The effect of heating time on the precipitation of spinel crystals in the CaO-SiO2-MgO-Al2O3-Cr2O3-FeO system was investigated in the laboratory. Scanning electron microscopy with energy-dispersive and X-ray diffraction were adopted to observe the microstructure, test the chemical composition, and determine the mineral phases of synthetic slags, and FactSage7.1 was applied to calculate the crystallization process of the molten slag. The results showed that the particle size of the spinel crystals increased from 9.42 to 10.73 μm, the calcium content in the spinel crystals decreased from 1.38 at% to 0.78 at%, and the content of chromium in the spinel crystal increased from 16.55 at% to 22.78 at% with an increase in the heating time from 0 min to 120 min at 1450 °C. Furthermore, the species of spinel minerals remained constant. Therefore, an extension in the heating time is beneficial for improving the stability of chromium in stainless steel slag.

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