Metals droplet assembling mechanism during carbon reduction of stainless steel pickling sludge

Liu, Songyan; Li, Qiuju; Wang, Ziyang; Yang, Fanxi; Lu, Xionggang

doi:10.1016/j.jclepro.2019.119580

Cited by 17 publications

(3 citation statements)

References 15 publications

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“…This indicated that the substantial quantity of CaSO 4 initially present in the SSPS converted to CaS due to the influence of temperature and carbon, whereas the Fe and Cr oxides also resulted in the formation of FeCr 2 O 4 . This was in agreement with the results of the thermodynamic and correlation studies described above [9,10,23].…”

Section: Mineral Phase Formation Of the Productsupporting

confidence: 92%

“…Wu et al [9] studied the effect of temperature, C/O ratio, and reduction time of low-temperature direct reduction-magnetic separation on the reduction of Cr in stainless steel sludge. Liu et al [10] proposed a semi-molten method for sludge reduction recovery after studying the growth and migration trend of low-meltingpoint Fe-Cr-C droplets. The described reductive separation and recovery methodology is distinguished by two principal characteristics: firstly, the sulfur element is removed to avoid its incorporation into the metal.…”

Section: Introductionmentioning

confidence: 99%

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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.

show abstract

Section: Mineral Phase Formation Of the Productsupporting

confidence: 92%

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

View full text Add to dashboard Cite

show abstract

“…Research by international scholars mainly focuses on the utilization of sludge resources and the detoxi cation of chromium. One of the detoxi cation pathways for chromium involves pyrometallurgical processes (Li et al 2018;Tang et al 2018;Liu et al 2019;Wu et al 2019), which are primarily used to isolate and recover chromium. However, due to the high sulfur content in stainless steel pickling sludge, re recovery will result in the emission of a large number of secondary pollutants such as SO 2 and NOx.…”

Section: Introductionmentioning

confidence: 99%

Effect of Cr-solidified/stabilized Water-quenched Slag on Strength and Leaching Characteristics of Blast Furnace Slag Cement

Zhao,

Zhang,

et al. 2024

Preprint

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This article presents an original study into the feasibility of using blast furnace slag and stainless steel pickling sludge to produce solidified/stabilized Cr slag micro-powder and its application in slag cement. A process route for utilizing blast furnace slag to dispose of pickling sludge online is proposed. The characteristics of Cr-solidified/stabilized water-quenched slag and composite slag cement are characterized, and the feasibility and economic viability of preparing mineral slag micro-powder are evaluated. The results demonstrate that the addition of sludge increases the grindability of water-quenched slag, with a specific surface area increasing from 971m²/kg to 1125m²/kg, and a glass phase content reaching 99%. Chromium in the mineral slag micro-powder exists either in solid solution within the glass network structure or in the form of spinel phase, significantly reducing its leaching toxicity. The prepared composite slag cement, with BP5 sample as the highest compression strength of 51.4MPa, achieves an activity index of S105. SEM analysis shows that the cement mortar samples cured for 28 days form a dense gel-like structure with good hydration performance. The leaching concentration of Cr in BP5 is the lowest, only 11.6 ug/L. The evaluation of process feasibility and economics shows that the solidified Cr slag powder prepared by large-scale online disposal of sludge is feasible. It can not only bring direct economic benefits, but also eliminate the environmental threats caused by hazardous waste, reduce energy consumption, and indirectly Reduce carbon emissions.

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Status of research on the resource utilization of stainless steel pickling sludge in China: a review

Shi

Zhang

Zhou

et al. 2023

Environ Sci Pollut Res

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Metals droplet assembling mechanism during carbon reduction of stainless steel pickling sludge

Cited by 17 publications

References 15 publications

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

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

Effect of Cr-solidified/stabilized Water-quenched Slag on Strength and Leaching Characteristics of Blast Furnace Slag Cement

Status of research on the resource utilization of stainless steel pickling sludge in China: a review

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