Control of silica polymerisation during ferromanganese slag sulphuric acid digestion and water leaching

Kazadi, Dieudonne M.; Groot, D.R.; Steenkamp, J.D.; Pöllmann, Herbert

doi:10.1016/j.hydromet.2016.06.024

Cited by 28 publications

(7 citation statements)

References 7 publications

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“…Leaching of copper slag with 2.5 mol/L H 2 SO 4 and 5 mol/L HNO 3 resulted in the formation of a gelatinous phase. The formation of a gelatinous phase causing problems during leaching and filtration was also reported in earlier studies investigating leaching of various types of slags with H 2 SO 4 [26][27][28].…”

Section: Discussionsupporting

confidence: 65%

Efficiency of Chemical and Biological Leaching of Copper Slag for the Recovery of Metals and Valorisation of the Leach Residue as Raw Material in Cement Production

et al. 2020

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Copper slags produced in vast quantities in smelting operations could be considered as secondary material sources instead of stockpiling them in landfills. This study investigates the recovery of valuable metals from copper slag and the valorisation of the leach residue as construction material in line with the principles of a circular economy. By taking into account that the environmental characterization of the as-received copper slag did not allow its disposal in landfills without prior treatment, chemical and biological leaching were tested for the recovery of metals. Pre-treatment with acids, namely HNO3 and H2SO4, resulted in the extraction of several target metals and the production of an almost inert waste. Despite the clearly better oxidative conditions prevailing in the bioleaching reactors, chemical leaching resulted in the higher dissolution of Cu (71% vs. 51%), Co (70% vs. 36%), and Zn (65% vs. 44%). The acid consumption was much lower during the bioleaching experiments compared to the chemical leaching. The bioleach residue was suitable for its use as supplementary cementitious material, showing a better performance than the reference sample without causing any detrimental effects to the calcium aluminate cement (CAC) quality. The complete valorisation of copper slags is expected to improve the economics of the process, by avoiding landfill costs and producing saleable products with high added value.

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Section: Discussionsupporting

confidence: 65%

Efficiency of Chemical and Biological Leaching of Copper Slag for the Recovery of Metals and Valorisation of the Leach Residue as Raw Material in Cement Production

et al. 2020

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“…It is challenging to separate solids from liquids because silica dissolves in an acidic media and produces silicic acid, which then polymerizes into silica gel. 64 They employed quick leach model, 65 which is based on a water-starved mechanism and expels silica from different silicaenriched minerals. It is suggested to the researchers to ensure this mechanism while extracting precious metal from slag compounds to overcome the obstacle.…”

Section: Solvent Extractionmentioning

confidence: 99%

“…In a study, it was stated that the formation of silica polymerization during water leaching and sulfuric acid digestion is a significant barrier to the hydrometallurgical treatment of ferromanganese slags. It is challenging to separate solids from liquids because silica dissolves in an acidic media and produces silicic acid, which then polymerizes into silica gel . They employed quick leach model, which is based on a water-starved mechanism and expels silica from different silica-enriched minerals.…”

Section: Metal Recovery Techniquesmentioning

confidence: 99%

An Overview of Precious Metal Recovery from Steel Industry Slag: Recovery Strategy and Utilization

Samanta

Das

Dhara

et al. 2023

Ind. Eng. Chem. Res.

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Steel slag is a solid waste of the steel industry, produced during steel production. Three types of slag, namely electric arc furnace (EAF), basic oxygen furnace (BOF), and Linz-Donawitz processed slag (LD-slag) are the steel industry byproducts. That slag comprises precious elements including zinc (Zn), chromium (Cr), iron (Fe), nickel (Ni), silicon (Si) , aluminum (Al), and vanadium (V) and is considered a secondary source of many metals. These metal constituents can be recovered from slags by employing mineral processing techniques like crushing, grinding, magnetic separation, eddy current separation, flotation, leaching, and/or roasting. Metal extraction from steelmaking slag and slag utilization is essential not only for conserving metal supplies but also for environmental protection. This review article evaluated and summarized various extraction methods including magnetic separation, roasting, pyrometallurgical method, hydrometallurgical and bio hydrometallurgical technique to recover precious metal constituents from obtained slag. The state-of-the-art of metal recovery from slag using the aforementioned methodologies and the merits, and demerits of each procedure have been illustrated comprehensively. Suggestions have been made to overcome the shortfall and or lacuna of the technology for better performance and efficiency. The opportunities and difficulties portion of this article paints a vivid picture of turning such a beneficial technology into a more adaptable procedure with some additions that may motivate and lead future research in new directions. The essence of this survey indicates that extracted metal and treated slag might be reutilized in various fields ranging from biomedical to fertilizer applications.

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“…Silica-gel formation can be avoided by dry digestion with concentrated acid. This creates water-starved conditions where the condensation of orthosilicic acid to silica gel is impossible [46]. Kazadi et al digested ferromanganese slags with concentrated H 2 SO 4 and the residue was leached with water [47].…”

Section: Electric Arc Furnace (Eaf) Slagmentioning

confidence: 99%

Hydrometallurgical Processes for the Recovery of Metals from Steel Industry By-Products: A Critical Review

Binnemans

Jones

Fernández

et al. 2020

J. Sustain. Metall.

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The state of the art for the recovery of metals from steel industry by-products using hydrometallurgical processes is reviewed. The steel by-products are different slags, dusts, and sludges from a blast furnace (BF), basic oxygen furnace (BOF), electric arc furnace (EAF), and sinter plant, as well as oily mill scale and pickling sludge. The review highlights that dusts and sludges are harder to valorize than slags, while the internal recycling of dusts and sludges in steelmaking is inhibited by their high zinc content. Although the objectives of treating BF sludges, BOF sludges, and EAF dust are similar, i.e., the removal of zinc and the generation of an Fe-rich residue to be returned to the steel plant, these three classes of by-products have specific mineralogical compositions and zinc contents. Because wide variations in the mineralogical composition and zinc content occur, it is impossible to develop a one-size-fits-all flow sheet with a fixed set of process conditions. The reason for the interest in EAF dust is its high zinc content, by far the highest of all steel by-products. However, EAF dust is usually studied from the perspective of the zinc industry. There are not only different concentrations of zinc, but also variations in the all-important ZnO/ZnFe2O4 (zincite-to-franklinite) ratio. In many chemical processes, only the ZnO dissolves, while the ZnFe2O4 is too refractory and reports to the residue. It only dissolves in concentrated acids, or if the dust is pre-treated, e.g., with a reductive roasting step. The dissolution of ZnFe2O4 in acidic solutions also brings significant amounts of iron in solution. Finally, due to its high potassium chloride content, sinter-plant dust could be a source of potassium for the fertilizer industry. Graphical Abstract

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Control of silica polymerisation during ferromanganese slag sulphuric acid digestion and water leaching

Cited by 28 publications

References 7 publications

Efficiency of Chemical and Biological Leaching of Copper Slag for the Recovery of Metals and Valorisation of the Leach Residue as Raw Material in Cement Production

Efficiency of Chemical and Biological Leaching of Copper Slag for the Recovery of Metals and Valorisation of the Leach Residue as Raw Material in Cement Production

An Overview of Precious Metal Recovery from Steel Industry Slag: Recovery Strategy and Utilization

Hydrometallurgical Processes for the Recovery of Metals from Steel Industry By-Products: A Critical Review

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