Green Mining | CELMIN – Utilisation of green chemicals in non-energy extractive industries
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CELMIN – Utilisation of green chemicals in non-energy extractive industries

Name: Utilisation of green chemicals in non-energy extractive industries: Preparation of modified nanofibrillar celluloses (NFC) for flotation, flocculation and dewatering, and water purification in mining industry

Acronym: CELMIN

Duration: 1.3.2014-30.8.2016

Total costs (€)/Tekes support: 505 687 € / 180 000 €

Leading research organization partner: University of Oulu/Fibre and particle engineering

Contact persons: Ari Ämmälä, University of Oulu, ari.ammala(at)


Research organization partners: Associação do Instituto Superior Tecnico para a Investigação e o Desenvolvimento (IST-ID, Portugal), Technical University of Cluj Napoca Romania North University Center of Baia Mare (NUCBM, Romania) , Sibelco Europe (Portugal), Sojitz Beralt Tin and Wolfram S.A. (Portugal),

Company partners: Agnico-Eagle Oy (Finland), Haarla Oy (Finland)

International partners: TU Bergakademie Freiberg, Germany

Number of reviewed publications, incl. submitted manuscripts: 6

Number of thesis: Master 1, Bachelor 2

Need and motivation of the project
The progressive industrialization of almost any country worldwide increases the demand of mineral and metal resources. The high demand leads to the processing of ores possessing a high complexity of its components. Annually around 400 million metric tons of ores are crushed and ground to particles to liberate the individual minerals. Froth flotation is the main beneficiation method for the efficient separation of desired minerals from gangue materials. Oil-derived flotation reagents used, however, are potentially harmful for human beings, animals and the environment, and therefore biocompatible candidates would be needed. Nanocellulose or cellulose nanocrystals are potential agents to replace commercial flotation reagents or flocculation agents in dewatering of finely ground particles to achieve a sustainable and efficient processing of ores.

Main set targets
The aim of the project was to design various chemical modifications affecting the functional properties of nanocelluloses and study those nanocelluloses with respect to their function in selective flotation (collector/depressant) and flocculation of finely dispersed mineral particles. Additionally, the role of adsorption interaction of cellulose chemicals on given minerals in the performance of froth flotation was aimed to study in order to get fundamental understanding for the basis of the development of tailored nanocellulose chemicals.


Key results

Project showed that cellulose can be chemically modified and properties adjusted such a way they can be used as green chemicals in froth flotation and dewatering/flocculation of mining industry. During the project it was showed that functionalized nanocellulose collectors, depressants or flocculants have a performance similar than oil-based chemicals with lower environmental impact. Functionalization based on increased hydrophilicity with increasing anionic charge and increased amphiphilicity by attaching the amino groups with extending alkyl chain lengths were designed. The importance of the free surface charges of the nanocellulose on the adsorption behavior on minerals, as well as on the particle- bubble attachments during flotation experiments was recorded. The investigations with binary quartz-hematite and quartz-alumina systems showed that nanocelluloses can selectively interact with one mineral rendering its wetting properties to more hydrophobic and thus separate the mineral efficiently from the gangue mineral. The results also suggest that nanocellulose carboxylation and sulfonation may be a route for selective flocculation e.g. in quartz/hematite separation.

Commercialization measures and/or potential
Cellulose based chemicals have a great potential in mineral processing. For commercialization, a novel route to produce nanocellulose chemicals by using deep eutectic solvents could be an economical and environmental sound alternative. 


List of publications

 Scientific papers and conference presentations

  1. Kemppainen, K. Suopajärvi, T. Laitinen, O. Ämmälä, A. Liimatainen, H. & Illikainen, M. (2016) Flocculation of fine hematite and quartz suspensions with anionic cellulose nanofibers. Chemical Engineering Science 148 (2016) 256-266. DOI: 10.1016/j.ces.2016.04.014
  2. Laitinen, O. Hartmann, R. Sirviö, J.A. Liimatainen, H. Rudolph, M. Ämmälä, A. and Illikainen, M. (2016) Alkyl aminated nanocelluloses in selective flotation of aluminium oxide and quartz. Chemical Engineering Science 144 (2016) 260-266. DOI: 10.1016/j.ces.2016.01.052
  3. Hartmann, R. Sirviö, J. Sliz, R. Laitinen, O. Liimatainen, H. Ämmälä, A. Fabritius, T. & Illikainen, M. (2016) Interactions between Cellulose Nanocrystals and Quartz: Adsorption and Wettability Studies. Colloids and Surfaces A: Physicochem. Eng. Aspects 489 (2016) 207–215. DOI: 10.1016/j.colsurfa.2015.10.022
  4. Sirviö, J. Visanko, M. Laitinen, O. Ämmälä, A. & Liimatainen, H. (2016) Amino-modified cellulose nanocrystals with adjustable hydrophobicity from combined regioselective oxidation and reductive amination. Carbohydrate Polymers 136 (2016) 581–587. DOI: 10.1016/j.carbpol.2015.09.089
  5. Laitinen O, Kemppainen K, Ämmälä A, Sirviö J, Liimatainen H & Niinimäki J. (2014) Use of chemically modified nanocelluloses in flotation of hematite and quartz. Industrial & Engineering Chemistry Research 2014, 53, 20092−20098. DOI: 10.1021/ie503415t
  6. Hartmann, R. Rudolph, M. Laitinen, O. Sirviö, J.A. Liimatainen, H. & Illikainen, M. (2016) Physicochemical Properties of Aminated Butyl-Nanocrystals in Correlation to the Flotation Response of Quartz. Accepted to IMPC 2016, Flotation: From Chemistry to Machines. Paper 719. Québec, Canada. 11th-15th September 2016.


M.Sc. Thesis

  1. Javier Cervera, Flotation response of binary quartz-hematite system. University of Oulu. 2016


B.Sc. Thesis

  1. Saku Kimpimäki, The Flotation Response of Quartz Using Aminated Cellulose Nanocrystals And Commercial Collectors. University of Oulu. 2016.
  2. Risto Aho, Use of modified nanocelluloses in aluminium oxide flotation (in Finnish). University of Oulu. 2015.


Posters and presentations

  1. Laitinen, O, Sirviö, J. Ämmälä A. Use of chemically modified nanocelluloses in mineral flotation. Poster presentation in Tekes Green Mining Annual Seminar 24-25 Nov.2014, Helsinki
  2. Laitinen O, Potential use of cellulose based chemicals in mineral processing. Tekes Green Mining Programme: Development of mineral processing technology 25.8.2015, University of Oulu.
  3. Ämmälä, A. Utilisation of green chemicals in non-energy extractive industries. ERA-MIN Closing Event 15.10.2015, Paris.