Desulfurization thermodynamics experiment of stainless steel pickling sludge

Li, Xiaoming; Lv, Ming; Yin, Wen; Zhao, Junxue; Yaru, Cui

doi:10.1007/s42243-018-0113-4

Cited by 18 publications

(8 citation statements)

References 6 publications

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“…Figure shows a picture of the sludge samples after drying and crushing, and it shows that the color of the SHPS samples varies from red to dark brown, depending on the composition and free water content of SHPS after drying . Sludge 1, sludge 2, and sludge 6 are dark brown to black, which may be related to the certain amount of black Fe 3 O 4 contained in these samples.…”

Section: Results and Discussionmentioning

confidence: 99%

Composition and Leaching Toxicity of Hydrochloric Acid Pickling Sludge Generated from the Hot-Dip Galvanized Steel Industry

Zhang

Shu

et al. 2022

ACS Omega

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Steel hydrochloric acid pickling sludge (SHPS), containing the heavy metals Fe, Zn, and Ni and a high chloride salt content, is considered a type of hazardous solid waste because of its potential harm to human health and the environment. In addition, the SHPS yield is large, but the main treatment currently used is only safe for landfills. Although studying the composition and leaching toxicity of SHPS is of great importance, only a small amount of related literature is available. This paper can help compensate for this deficiency. SHPS is analyzed from the aspects of its formation mechanism, pH, moisture content, elemental concentration, phase composition, microstructure, and leaching toxicity. The results show that its pH ranges from 2.25 to 11.11, and the moisture content ranges from 45.47% to 83.34%. Additionally, the concentration of Fe is the highest, with values from 29.80% to 50.65%, while other alkali metal elements, namely, Ca, K, and Na, have values of 0.36% to 23.07%, 0.02% to 19.82%, and 0.38% to 3.31%, respectively. Heavy metal elements, namely, Zn, Ni, Mn, Cr, and Pb, have values of 0.02% to 14.88%, 0.001% to 0.05%, 0.03% to 0.38%, 0.01% to 0.09%, and 0.02% to 0.19%, respectively. Anions, namely, SO 4 2– , Cl – , F – , and NO 3 – , have contents of 0.09% to 0.34%, 0.54% to 5.73%, 0.001% to 0.04%, and 0.01% to 0.15%, respectively. X-ray diffraction (XRD) analysis shows that Fe and Zn are mainly present in oxides, Ca is present as CaO and CaCO 3 , and chlorine is present in NaCl. Moreover, scanning electron microscopy (SEM) analysis shows that the microscopic structure consists mainly of bright and fluffy irregular spheres; stripes; flakes; and dark, very small irregular particles. The leaching toxicity test based on HJ/T 299-2007 (China) was performed, where SHPS samples were treated with a mixed solution of sulfuric acid, nitric acid, and pure water (pH = 3.20 ± 0.05) at a liquid-to-solid ratio of 10:1 for a period of 18 h. The leachate was filtered and analyzed for Cr, Ni, Mn, Zn, etc. The leaching results indicate that Zn and Ni are the main elements that cause SHPS to be hazardous to the environment. These research results can provide a reference for later researchers studying the effective treatment of SHPS, such as more effective treatments for reducing toxicity and resource utilization.

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Section: Results and Discussionmentioning

confidence: 99%

Composition and Leaching Toxicity of Hydrochloric Acid Pickling Sludge Generated from the Hot-Dip Galvanized Steel Industry

Zhang

Shu

et al. 2022

ACS Omega

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“…In contrast, the formation of solid-phase CaO and SO 2 by CaSO 4 is not thermodynamically favorable, and the minimum temperature for the reaction to occur needs to be higher than 800 • C, which has been confirmed in many studies [4,9,23]. It can be seen from Figure 2b that at the considered slag bath reaction temperature, FeCr 2 O 4 and MgCr 2 O 4 are conducive to carbothermal reduction to form alloys, and the reaction of FeCr 2 O 4 combined with MgO to form MgCr 2 O 4 mineral phase also exists.…”

Section: A Thermodynamic Model Of Pre-reduction and Slag-bath Smeltingmentioning

confidence: 89%

“…Predominantly, domestic manufacturers use H 2 SO 4 or hybrid acids for surface treatment, producing high-sulfur sludge through lime neutralization, which contains S (5 wt%~9 wt%), Cr (3 wt%~5 wt%), and Fe (15 wt%~22 wt%) [2,3]. Classified as hazardous waste (HW17) by the "National Dangerous Waste Catalog (2016)" for its toxicity and corrosiveness [4], SSPS management is now tightly regulated under the "Control Law of Solid Waste Environmental Pollution" [5,6]. Therefore, managing SSPS within the plant and throughout the production line is of paramount importance and demands immediate focus.…”

Section: Introductionmentioning

confidence: 99%

In-Line Co-Processing of Stainless Steel Pickling Sludge Using Argon Oxygen Decarburization Slag Bath: Behavior and Mechanism

Zhao,

Zhang,

Yuan

et al. 2024

Sustainability

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Stainless steel pickling sludge (SSPS) is classified as hazardous solid waste, while Argon Oxygen Decarburization (AOD) slag is challenging to utilize due to the leaching toxicity of Cr. This study introduces a novel in-line co-processing technique for AOD slag and SSPS, parallel to the steelmaking process, aimed at metal recovery, sulfur fixation, and slag detoxification: pre-treatment-AOD slag bath approach. The transformations and migrations of sulfur and metal elements, such as Fe and Cr, in the co-processed mixture were analyzed using thermogravimetric–mass spectrometry (TG-MS) and scanning electron microscopy–energy dispersive spectroscopy (SEM-EDS). The results indicated that sulfur in SSPS could be transformed from CaSO4 to CaS under controlled low pre-reduction temperatures (below 800 °C), facilitating its stabilization in the slag and achieving a sulfur fixation rate of over 99%. Metal elements, including iron and chromium, first formed a small portion of spinel (FeCr2O4) during the pre-reduction phase, then Fe-Cr or Fe-Cr-C-based alloy particles were rapidly formed at high temperatures and in the presence of reducers in the slag bath (1550 °C), aggregating and growing spontaneously, ultimately achieving a metal recovery rate of over 95%. Furthermore, a reaction model for SSPS briquettes in the AOD slag bath was established to further reveal the mechanisms of sulfur, iron, and chromium stabilization and migration, thereby providing a basis for the harmless disposal of both materials. The product alloys are expected to be used as additives in stainless steel production, while the harmless slag could be safely utilized in the preparation of cementitious auxiliary materials.

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“…Therefore, it is essential to develop valuable metal recovery technology from stainless steel pickling sludge with large consumption, good comprehensive utilization effect, high efficiency, and no secondary pollution. At present, some researchers have carried out the recovery of Fe, Cr, and Ni from stainless steel pickling sludge using reduction smelting, which can achieve the Fe, Cr, and Ni enriched in alloy phase [22][23][24]. However, the fundamental theory and valuable metal distribution behavior on the reduction smelting of stainless steel pickling sludge have not been reported in the literature [25].…”

Section: Introductionmentioning

confidence: 99%

Thermodynamic Analysis on the Reduction Smelting of Stainless Steel Pickling Sludge

Zhang

et al. 2021

J. Sustain. Metall.

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The thermodynamic analysis on the reduction smelting of stainless steel pickling sludge was reported in this paper. The predominance area diagram of Fe-Ni-Cr-C-O system, and phase diagrams of CaF 2 -SiO 2 -CaO-Al 2 O 3 -MgO system were first thermodynamically constructed. The effects of temperature, CaF 2 content, and SiO 2 addition on the melting temperature and viscosity of slag were calculated. Then the reduction smelting experiments were carried out under various SiO 2 addition at 1400 °C. The thermodynamical results show that the reduction reaction can occur in the Ni + Fe + Cr 2 O 3 phase stable region by controlling the relevant thermodynamic conditions during reduction, which can realize the Fe-Ni phase enriched in the alloy. The experiments results indicate that the variation of SiO 2 addition can affect the distribution of Fe, Cr, and Ni elements in the alloy and slag. When the SiO 2 addition is 50%, the contents of Fe and Cr in the alloy can reach 72.39% and 20.98%, respectively. The mineralogy of the reduction products demonstrated that the distinguishable crystal phase in the alloy mainly contained FeNi intermetallic compounds, and the slag was mainly composed of fluorite and calcium silicate.

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Desulfurization thermodynamics experiment of stainless steel pickling sludge

Cited by 18 publications

References 6 publications

Composition and Leaching Toxicity of Hydrochloric Acid Pickling Sludge Generated from the Hot-Dip Galvanized Steel Industry

Composition and Leaching Toxicity of Hydrochloric Acid Pickling Sludge Generated from the Hot-Dip Galvanized Steel Industry

In-Line Co-Processing of Stainless Steel Pickling Sludge Using Argon Oxygen Decarburization Slag Bath: Behavior and Mechanism

Thermodynamic Analysis on the Reduction Smelting of Stainless Steel Pickling Sludge

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