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Lime/Sodium Carbonate Treated Seawater to Improve Flocculation and Sedimentation of Clay-Based Tailings

Seawater treated with lime and sodium carbonate in different proportions to reduce magnesium and calcium contents is used in flocculation and sedimentation tests of artificial quartz and kaolin tailings. Solid complexes were separated from water by vacuum filtration, and factors such as lime/sodium...

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Autores principales: Pulgar, Francisco, Ayala, Luis, Jeldres, Matías, Robles, Pedro, Toledo, Pedro G., Salazar, Iván, Jeldres, Ricardo I.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: MDPI 2021
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8659028/
https://www.ncbi.nlm.nih.gov/pubmed/34883608
http://dx.doi.org/10.3390/polym13234108
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author Pulgar, Francisco
Ayala, Luis
Jeldres, Matías
Robles, Pedro
Toledo, Pedro G.
Salazar, Iván
Jeldres, Ricardo I.
author_facet Pulgar, Francisco
Ayala, Luis
Jeldres, Matías
Robles, Pedro
Toledo, Pedro G.
Salazar, Iván
Jeldres, Ricardo I.
author_sort Pulgar, Francisco
collection PubMed
description Seawater treated with lime and sodium carbonate in different proportions to reduce magnesium and calcium contents is used in flocculation and sedimentation tests of artificial quartz and kaolin tailings. Solid complexes were separated from water by vacuum filtration, and factors such as lime/sodium carbonate ratio, kaolin content, flocculation time, and flocculant dose are evaluated. The growth of the aggregates was captured in situ by a focused beam reflectance measurement (FBRM) probe. Solid magnesium and calcium complexes are formed in raw seawater at pH 11, impairing the performance of flocculant polymers based on polyacrylamides. The results show that the settling rate improved when the treatment’s lime/sodium carbonate ratio increased. That is, when a greater removal of magnesium is prioritized over calcium. The amount of magnesium required to be removed depends on the mineralogy of the system: more clay will require more significant removal of magnesium. These results respond to the structural changes of the flocs, achieving that the more magnesium is removed, the greater the size and density of the aggregates. In contrast, calcium removal does not significantly influence flocculant performance. The study suggests the necessary conditions for each type of tailing to maximize water recovery, contributing to the effective closure of the water cycle in processes that use seawater with magnesium control.
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spelling pubmed-86590282021-12-10 Lime/Sodium Carbonate Treated Seawater to Improve Flocculation and Sedimentation of Clay-Based Tailings Pulgar, Francisco Ayala, Luis Jeldres, Matías Robles, Pedro Toledo, Pedro G. Salazar, Iván Jeldres, Ricardo I. Polymers (Basel) Article Seawater treated with lime and sodium carbonate in different proportions to reduce magnesium and calcium contents is used in flocculation and sedimentation tests of artificial quartz and kaolin tailings. Solid complexes were separated from water by vacuum filtration, and factors such as lime/sodium carbonate ratio, kaolin content, flocculation time, and flocculant dose are evaluated. The growth of the aggregates was captured in situ by a focused beam reflectance measurement (FBRM) probe. Solid magnesium and calcium complexes are formed in raw seawater at pH 11, impairing the performance of flocculant polymers based on polyacrylamides. The results show that the settling rate improved when the treatment’s lime/sodium carbonate ratio increased. That is, when a greater removal of magnesium is prioritized over calcium. The amount of magnesium required to be removed depends on the mineralogy of the system: more clay will require more significant removal of magnesium. These results respond to the structural changes of the flocs, achieving that the more magnesium is removed, the greater the size and density of the aggregates. In contrast, calcium removal does not significantly influence flocculant performance. The study suggests the necessary conditions for each type of tailing to maximize water recovery, contributing to the effective closure of the water cycle in processes that use seawater with magnesium control. MDPI 2021-11-25 /pmc/articles/PMC8659028/ /pubmed/34883608 http://dx.doi.org/10.3390/polym13234108 Text en © 2021 by the authors. https://creativecommons.org/licenses/by/4.0/Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).
spellingShingle Article
Pulgar, Francisco
Ayala, Luis
Jeldres, Matías
Robles, Pedro
Toledo, Pedro G.
Salazar, Iván
Jeldres, Ricardo I.
Lime/Sodium Carbonate Treated Seawater to Improve Flocculation and Sedimentation of Clay-Based Tailings
title Lime/Sodium Carbonate Treated Seawater to Improve Flocculation and Sedimentation of Clay-Based Tailings
title_full Lime/Sodium Carbonate Treated Seawater to Improve Flocculation and Sedimentation of Clay-Based Tailings
title_fullStr Lime/Sodium Carbonate Treated Seawater to Improve Flocculation and Sedimentation of Clay-Based Tailings
title_full_unstemmed Lime/Sodium Carbonate Treated Seawater to Improve Flocculation and Sedimentation of Clay-Based Tailings
title_short Lime/Sodium Carbonate Treated Seawater to Improve Flocculation and Sedimentation of Clay-Based Tailings
title_sort lime/sodium carbonate treated seawater to improve flocculation and sedimentation of clay-based tailings
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8659028/
https://www.ncbi.nlm.nih.gov/pubmed/34883608
http://dx.doi.org/10.3390/polym13234108
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