Application of Nanofiltration Technology to Improve Sea Water Neutralization of Bayer Process Residue

Taylor, Kelvin; Mullett, Mark; Fergusson, Lee; Adamson, Helen; Wehrli, Juerg

doi:10.1007/978-3-319-48160-9_14

Cited by 6 publications

(6 citation statements)

References 2 publications

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“…The detection of amorphous phases by XRD may be consistent with the presence of Al(OH) 3 species (Equation ) as aluminates were known to be present in Bayer liquor

Al {(normalOH)}_{4 (normalaq)}^{-} \to Al {(normalOH)}_{3 (s)} + {OH}_{(normalaq)}^{-}

…”

Section: Resultssupporting

confidence: 57%

“…Due to the presence of calcium in seawater, XRD patterns for all obtained Bayer precipitates show calcite and aragonite were formed along with hydrotalcite. Taylor et al reported that in Bayer liquor, the main alkalinity providing species were hydroxides (OH − ), aluminate ions (Al(OH) 4 − ), and carbonates (CO 3 2− ). Thus, the presence of calcium carbonate upon the addition of seawater (source of Ca) to Bayer liquor can be explained in terms of Equation

{Ca}_{(normalaq)}^{2 +} + {CO}_{3 (normalaq)}^{2 -} \to {CaCO}_{3 (s)}

…”

Section: Resultsmentioning

confidence: 99%

“…The obtained liquor is strongly alkaline (pH ranging from 10 to 13) due to the presence of high concentrations of sodium aluminate, sodium carbonate, and sodium hydroxide. Therefore, it is necessary to reduce the pH of the Bayer liquor to a value of 8.5–8.9 prior to disposal …”

Section: Introductionmentioning

confidence: 99%

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Acid Mine Drainage Treatment Using Bayer Precipitates Obtained from Seawater Neutralization of Bayer Liquor

2018

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Bayer precipitates from the seawater neutralization of Bayer liquor waste from the alumina industry are shown to be a prospective solution for the remediation of acid mine drainage (AMD) water. Precipitates are varied in composition, albeit they are generally comprised of hydrotalcite (Mg 6 Al 2 (OH) 16 CO 3 ∙ x H 2 O), calcite (CaCO 3 ), aragonite (CaCO 3 ), mixed metal hydroxides (Mg 2 Al(OH) 7 ), and halite (NaCl). Brucite (Mg(OH) 2 ) is detected for lower Bayer liquor concentrations (1–3 g L −1 Al 2 O 3 ) when the concentrations of aluminum and hydroxyl species are insufficient to promote hydrotalcite formation. The neutralizing capacity of the precipitates also varies with Bayer liquor composition. Treatment of AMD water with Bayer precipitates met discharge pH guidelines. The dissolution of hydrotalcite and brucite (1–3 g L −1 Bayer precipitates only) is responsible for the Bayer precipitate's neutralizing capacity, while calcium carbonate has a buffering affect at around pH 7. Manganese ions are the most challenging species to remove because high pH values are required (pH > 9), which is not possible with all precipitates tested. One caveat is that increasing the degree of manganese removal generates issues with excessive dissolved aluminum which exceeds discharge limits. Future research should address this latter problem and facilitate implementation of this approach to AMD remediation.

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“…The detection of amorphous phases by XRD may be consistent with the presence of Al(OH) 3 species (Equation ) as aluminates were known to be present in Bayer liquor

Al {(normalOH)}_{4 (normalaq)}^{-} \to Al {(normalOH)}_{3 (s)} + {OH}_{(normalaq)}^{-}

…”

Section: Resultssupporting

confidence: 57%

{Ca}_{(normalaq)}^{2 +} + {CO}_{3 (normalaq)}^{2 -} \to {CaCO}_{3 (s)}

…”

Section: Resultsmentioning

confidence: 99%

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Acid Mine Drainage Treatment Using Bayer Precipitates Obtained from Seawater Neutralization of Bayer Liquor

2018

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“…The total economic advantages is case specific; however, it is proposed that the majority of alumina refineries using the seawater neutralization process would benefit from the implementation of this technology. The report by Taylor et al, 24 provides more detail on the economic advantages of using membrane technology in the seawater neutralization process.…”

Section: Mineralogical Compositionmentioning

confidence: 99%

“…This study is an extension of the work previously conducted by Taylor et al in 2011, which focused on the engineering aspects of using nanofiltered seawater. 24 Their aims were to determine the extent to which seawater could be concentrated using NF membranes before scaling commenced or before the osmotic pressure became limiting. In this study, a comparative reactivity of seawater and seawater NF concentrate has been undertaken to gain an understanding of the equipment capacities required and capital reduction benefits that could reasonably by anticipated by alumina refiners.…”

Section: Introductionmentioning

confidence: 99%

Minimization of Bauxite Residue Neutralization Products Using Nanofiltered Seawater

Couperthwaite

Johnstone

Mullett³

et al. 2014

Ind. Eng. Chem. Res.

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Currently, open circuit Bayer refineries pump seawater directly into their operations to neutralize the caustic fraction of the Bayer residue. The resulting supernatant has a reduced pH and is pumped back to the marine environment. This investigation has assessed modified seawater sources generated from nanofiltration processes to compare their relative capacities to neutralize bauxite residues. An assessment of the chemical stability of the neutralization products, neutralization efficiency, discharge water quality, bauxite residue composition, and associated economic benefits has been considered to determine the most preferable seawater filtration process based on implementation costs, savings to operations and environmental benefits. The mechanism of neutralization for each technology was determined to be predominately due to the formation of Bayer hydrotalcite and calcium carbonate; however, variations in neutralization capacity and efficiencies have been observed. The neutralization efficiency of each feed source has been found to be dependent on the concentration of magnesium, aluminum, calcium, and carbonate. Nanofiltered seawater, with approximately double the amount of magnesium and calcium required half the volume of seawater to achieve the same degree of neutralization. These studies have revealed that multiple neutralization steps occur throughout the process using characterization techniques such as X-ray diffraction (XRD), infrared (IR) spectroscopy, and inductively coupled plasma optical emission spectroscopy (ICP-OES).

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The Conversion and Sustainable Use of Alumina Refinery Residues: Global Solution Examples

Fergusson¹

2013

Essential Readings in Light Metals

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Application of Nanofiltration Technology to Improve Sea Water Neutralization of Bayer Process Residue

Cited by 6 publications

References 2 publications

Acid Mine Drainage Treatment Using Bayer Precipitates Obtained from Seawater Neutralization of Bayer Liquor

Acid Mine Drainage Treatment Using Bayer Precipitates Obtained from Seawater Neutralization of Bayer Liquor

Minimization of Bauxite Residue Neutralization Products Using Nanofiltered Seawater

The Conversion and Sustainable Use of Alumina Refinery Residues: Global Solution Examples

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