University of Oulu

Coelho Braga de Carvalho, A.L., Ludovici, F., Goldmann, D. et al. Silylated Thiol-Containing Cellulose Nanofibers as a Bio-Based Flocculation Agent for Ultrafine Mineral Particles of Chalcopyrite and Pyrite. J. Sustain. Metall. 7, 1506–1522 (2021).

Silylated thiol‑containing cellulose nanofibers as a bio‑based flocculation agent for ultrafine mineral particles of chalcopyrite and pyrite

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Author: de Carvalho, Ana Luiza Coelho Braga1; Ludovici, Feliciana2; Goldmann, Daniel1;
Organizations: 1Institute of Mineral and Waste Processing, Waste Disposal and Geomechanics, Department of Mineral and Waste Processing, Clausthal University of Technology, Walther-Nernst-Straße 9, 38678 Clausthal-Zellerfeld, Germany
2Fiber and Particle Engineering Research Unit, University of Oulu, Erkki Koiso-Kanttilankatu, 90014 Oulu, Finland
3Modelling and Mineral Processing Research Lab (LaMPPMin), Federal University of Catalão (UFCAT), 08 street 25, Catalão, GO 75705-321, Brazil
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 7.3 MB)
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Language: English
Published: Springer Nature, 2021
Publish Date: 2022-01-20


A considerable amount of very fine particles can be found, e.g., stored in tailing ponds, and they can include valuable or hazardous minerals that have the potential to be recovered. Selective flocculation, i.e., the formation of larger aggregates from specific minerals, offers a promising approach to improve the recovery of ultrafine particles. This study focuses on the use of a new bio-based flocculation agent made of silylated cellulose nanofibers containing a thiol-functional moiety (SiCNF). Flocculation was performed in separated systems of ultrafine mineral dispersions of pyrite, chalcopyrite, and quartz in aqueous alkaline medium. The flocculation performance of SiCNF was addressed in terms of the turbidity reduction of mineral dispersions and the floc size, and the results were compared with the performance of a commercial anionic polyacrylamide. SiCNF exhibited a turbidity removal efficiency of approximately 90%–99% at a concentration of 4000–8000 ppm with chalcopyrite and pyrite, whereas the turbidity removal of quartz suspension was significantly lower (a maximum of approximately 30%). The sulfide particles formed flocs with a size of several hundreds of micrometers. The quartz in turn did not form any visible flocs, and the dispersion still had a milky appearance after dosing 12,000 ppm of the flocculant. These results open a promising path for the investigation of SiCNF as a selective flocculation agent for sulfide minerals.

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Series: Journal of sustainable metallurgy
ISSN: 2199-3823
ISSN-E: 2199-3831
ISSN-L: 2199-3823
Volume: 7
Issue: 4
Pages: 1506 - 1522
DOI: 10.1007/s40831-021-00439-y
Type of Publication: A1 Journal article – refereed
Field of Science: 221 Nanotechnology
116 Chemical sciences
Funding: The research leading to these results received funding from the Horizon 2020 Program of the European Union under Grant Agreement No. 812580 (MSCA-ETN SULTAN). This publication reflects only the view of the authors, the European Union is exempted from any liability. Project website:
EU Grant Number: (812580) SULTAN - European Training Network for the remediation and reprocessing of sulfidic mining waste sites
Copyright information: © The Author(s) 2021. Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit