Valorisation of waste galvanizing dross: Emphasis on recovery of zinc with zero effluent strategy

Sinha, Shandip Kumar; Choudhari, R.; Mishra, Dillip Kumar; Shekhar, Shashank; Agrawal, Atul; Sahu, Κ. K.

doi:10.1016/j.jenvman.2019.109985

Cited by 9 publications

(3 citation statements)

References 31 publications

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“…Hot-dip galvanizing is a common corrosion-preventive treatment for metals [1][2][3]. It is widely used for its strong corrosion protection, low maintenance, high aesthetics, and malleability, and hot-dip galvanizing accounts for nearly half of all zinc used [4][5][6]. However, during continuous hot-dip galvanizing process, the zinc bath is often saturated with iron and hot-dip galvanizing slag inevitably precipitates.…”

Section: Introductionmentioning

confidence: 99%

Purification and Recovery of Hot-Dip Galvanizing Slag via Supergravity-Induced Cake-Mode Filtration

Zhang,

Wang,

Lan

et al. 2024

Metals

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The elimination and retrieval of slag produced during the hot-dip galvanizing process are crucial in reducing plating defects and enhancing economic efficiency. Hot-dip galvanizing slag can be separated and purified efficiently by using graphite carbon felt filtration in a supergravity field. The effects of the gravity coefficient (G), separation temperature (T), and separation time (t) on the separation efficiency were investigated. Under the optimal conditions as G = 300, T = 460 °C, and t = 120 s, these conditions yielded filtered zinc with 0.022 wt% Fe and 1.097 wt% Al. The separation efficiencies achieved were 87% for the acquisition ratio of filtered zinc (AZn), 93.67% for the recovery ratio of zinc (RZn), and 96.01% for the loss ratio of iron (LFe). Based on these laboratory findings, an amplified centrifugal separation apparatus was conceptually designed for future online separation and recycle of zinc slag on an engineering scale. The filtered zinc obtained from this apparatus contained 0.027 wt% Fe and 1.844 wt% Al, while the recovery ratio of zinc (RZn) and the loss ratio of iron (LFe) achieved 85.97% and 95.47%, respectively.

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Section: Introductionmentioning

confidence: 99%

Purification and Recovery of Hot-Dip Galvanizing Slag via Supergravity-Induced Cake-Mode Filtration

Zhang,

Wang,

Lan

et al. 2024

Metals

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“…Zinc exists in readily soluble forms, posing an additional source of contamination for both soils and waters in galvanizing waste. Approximately 80% of the world's zinc production is used for steel galvanization prior to the corrosion process (Sinha et al 2020). Given the high zinc content, galvanic wastes can be considered valuable secondary raw materials, justifying the exploration of new methods for recovering Zn from these waste materials .…”

Section: Introductionmentioning

confidence: 99%

Study of Zn(II) ion removal from galvanic sludge by geopolymers

2023

Archives of Environmental Protection

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The galvanic sludges contain a number of toxic heavy metals, potentially mobilized as chemically active ions under environmental conditions as. This study explores the application of fly ash-based geopolymers for the removal of Zn ions from galvanizing sludge. In this study, geopolymers, synthesized via the geopolymerization method, were used to remove Zn from post-galvanized sewage sludge. Two types of geopolymers were used, derived from ash from coal combustion and biomass combustion. Structural, morphological, and surface properties were characterized using FTIR and SEM, respectively. In addition, BET and Langmuir isotherms, along with analyses such as t-Plot and BJH method for porous solids were conducted. The results indicate that the geopolymer derived from coal combustion ash is a more effective sorbent for Zn(II) ions, exhibiting a removal efficiency of 99.9%, compared to 40.7% for the geopolymer derived from biomass combustion ash. The FTIR spectra analysis reveals the presence of bonds between the -OH and/or Si-OH groups on the geopolymers' surface and the Zn(II) ions. The environmentally and economically advantageous process maximizes the recovery of a valuable component at minimal cost, yielding relatively clean monometallic waste suitable for reuse.

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“…A high purity of zinc powder (99.5%) was obtained at room temperature in efficiency of 86% at 5 amp/dm 2 current density, 1.2 V impressed voltage, concentration of electrolyte 16 g/L Zn and 220 g/L NaOH. Sinha et al [35] established a leaching-precipitation-crystallization route to produce high-grade zinc sulfate and phosphate salts, along with by-products. Zinc content in the studied sample was 97.5%.…”

Section: Introductionmentioning

confidence: 99%

Theoretical and Practical Evaluation of the Feasibility of Zinc Evaporation from the Bottom Zinc Dross as a Valuable Secondary Material

et al. 2022

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This study presents a theoretical and practical evaluation of zinc evaporation from bottom zinc dross (hard zinc) as a secondary zinc source (zinc content approximately 94–97%), which originates in the batch hot-dip galvanizing process. The thermodynamics of the zinc evaporation process were studied under the normal pressure (100 kPa) in the inert atmosphere, using argon with flow rate 90 mL/min. Samples were subjected to the evaporation process for 5, 10 and 20 min under the temperature of 700 °C and 800 °C, respectively. For the theoretical thermodynamic study, HSC Chemistry 6.1 software was used and final products, as well as residuals after the evaporation process, were analyzed by SEM (Scanning Electron Microscopy) and EDX (Energy Dispersive X-ray). Calculated and experimental argon consumption in the process of zinc evaporation has been compared. A high purity zinc with efficiency over 99% was reached. Due to a dynamic regime, argon consumption at the temperature of 700 °C and 800 °C were 7 times and 3 times, respectively, less than calculated.

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Valorisation of waste galvanizing dross: Emphasis on recovery of zinc with zero effluent strategy

Cited by 9 publications

References 31 publications

Purification and Recovery of Hot-Dip Galvanizing Slag via Supergravity-Induced Cake-Mode Filtration

Purification and Recovery of Hot-Dip Galvanizing Slag via Supergravity-Induced Cake-Mode Filtration

Study of Zn(II) ion removal from galvanic sludge by geopolymers

Theoretical and Practical Evaluation of the Feasibility of Zinc Evaporation from the Bottom Zinc Dross as a Valuable Secondary Material

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