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Organosolv Lignin Particles as a Partial Replacement of Xanthate Collector in a Copper Sulfide Ore Flotation: Scale-up Study
Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik. (Biochemical Process Engineering)
Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik. (Biochemical Process Engineering)ORCID-id: 0000-0002-1132-8947
Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik. (Biochemical Process Engineering)ORCID-id: 0000-0002-3687-6173
Boliden Mineral AB, SE-936 81 Boliden, Sweden.
Visa övriga samt affilieringar
(Engelska)Manuskript (preprint) (Övrigt vetenskapligt)
Abstract [en]

The transition to a sustainable, green economy indeed requires more access to strategic/critical metals for renewable energy technologies while simultaneously reducing reliance on fossil fuels and their byproducts. In mineral processing, various research for an environment-friendly flotation reagents have been ongoing for many years. In this paper, the potential of organosolv lignin particles (OLP) as a biobased reagent that can improve the grade and recovery of Cu was demonstrated using real sulfide ore. The main advantage of this process is that it requires low dosage of OLP in the tested condition and set-up. The initial laboratory batch flotation tests showed that potassium amyl xanthate (PAX) can be partially replaced with OLP by 50% and in the absence of depressant, lime. These results were further verified in semi-pilot flotation tests that showed an increase in recovery by 8% in the rougher stage and comparable grade in the final cleaner stage when using the OLP-PAX mixture with respect to PAX at full dosage. In general, this paper presents the progress towards validating the viability of OLP as a biobased flotation reagent suitable for industrial-scale applications.

Nyckelord [en]
Organosolv Lignin, Nanoparticles, Froth Flotation, Sulfides, Chalcopyrite
Nationell ämneskategori
Kemiska processer
Forskningsämne
Biokemisk processteknik
Identifikatorer
URN: urn:nbn:se:ltu:diva-105137OAI: oai:DiVA.org:ltu-105137DiVA, id: diva2:1852193
Tillgänglig från: 2024-04-17 Skapad: 2024-04-17 Senast uppdaterad: 2024-04-17
Ingår i avhandling
1. Potential of Organosolv Lignin Nanoparticles as a Sustainable Flotation Reagent: Towards a Low-Carbon Footprint Mining Industry
Öppna denna publikation i ny flik eller fönster >>Potential of Organosolv Lignin Nanoparticles as a Sustainable Flotation Reagent: Towards a Low-Carbon Footprint Mining Industry
2024 (Engelska)Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
Alternativ titel[sv]
Potential för organosolv lignin nanopartiklar som en hållbar flotations reagens : ett steg mot en gruvindustri med ett lågt koldioxidavtryck
Abstract [en]

The green transition is driving a steep increase in the demand for minerals, which has put the focus on more responsible and sustainable mining practices as there is a growing pressure on mining operations to minimise their environmental footprint, mitigate risks in neighbouring communities, and decrease the consumption of natural resources. In 2022, mineral froth flotation was used to recover 18 million tonnes of copper from copper ore, accounting for 80% of total copper mine output. The mineral froth flotation process can be made more sustainable through the use of bio-based and biodegradable flotation reagents. Currently, xanthates are used as collectors for the recovery of copper-bearing sulfide minerals from sulfide ores. However, xanthates are fossil-based and pose significant risks, particularly to aquatic life and ecosystems. Additionally, a significant part of xanthates is currently obtained from production sites in Asia, which can lead to supply dependency and delays, as evident during the global pandemic.

The aim of this thesis was to develop an efficient, sustainable, and environmentally friendly mineral froth flotation process based on total or partial replacement of xanthates with bio-based, biodegradable, and low-carbon footprint organosolv lignin particles (OLP). The lignin was obtained through organosolv fractionation of residual forest biomass, i.e. spruce and birch. The particles were produced via solvent exchange method from the homogenized lignin solution. As a result, 4 different particle types were produced: birch nanoparticles (BN), birch microparticles (BM), spruce nanoparticles (SN), and spruce microparticles (SM). At first, the characterization and surface chemistry study of the OLP was carried out to deepen the understanding of interaction mechanism between the OLP and mineral surfaces. The lignin was characterized by gel permeation chromatography and nuclear magnetic resonance for its molecular size and content of functional groups. While morphology, surface charge and stability in dispersion of the particles was determined using scanning electron microscopy, ζ-potential, and Turbiscan. All 4 particles were spherical with the diameter around 100 nm for nanoparticles and 1μm for microparticles. The ζ-potential measurement showed the surface variation caused by the difference in size and content of functional groups. Spruce particles, SN and SM, had higher negative charge due to higher content of carboxylic and total phenolic groups. Under alkali conditions, the ζ-potential below -20mV for all particles, with the lowest at −55.1 mV for SM. Finaly, the interaction of OLP with mineral surfaces was examined using quartz crystal microbalance. While the attachment of all OLP was very rigid for both, chalcopyrite and pyrite surfaces, the affinity for attachment was notably greater in the case of pyrite compared to chalcopyrite.

The OLP was tested in proof-of-concept study on three different ore samples, and improvements in the flotation performance was observed, including better selectivity and increased recovery. The further evaluation of the OLP as flotation reagent was conducted with copper ore samples. The flotation trials were carried out with 600 g of ore sample in laboratory flotation cell. Starting with the dosage study, the results were confirmed in rougher-cleaner flotation tests. However, the OLP could not be used as a sole collector, it was shown that significant part of xanthate in the flotation mix could be replaced by OLP resulting in improved copper recovery and selectivity. Additionally, a synergy was observed when the OLP and xanthate mixture was used as combined reagents performed better than each of them separately at the same dosage. The copper recovery was increased from 82.2% to 88.7% in a semi-pilot rougher flotation when 50% of xanthate was replaced by OLP compared to the xanthate alone. Significant depression of iron recovery was observed when the OLP was utilized, even in absence of lime. Thus, the OLP reagents eliminated the need for lime, which is required on an industrial scale. Further positive effect of OLP application was indicated recovery of other valuable elements in the concentrates, such as cobalt and molybdenum, while there was no increase in penalty elements. The amount of OLP needed was up to 10 g/ton of ore, which is very small amount, and it is roughly 10 times less compared to any other modifier used in such a process. Therefore, this thesis demonstrates the potential of OLP as flotation reagent. If implemented, the proposed flotation system would lead to better resource efficiency and lower environmental impact.

Ort, förlag, år, upplaga, sidor
Luleå: Luleå University of Technology, 2024
Serie
Doctoral thesis / Luleå University of Technology 1 jan 1997 → …, ISSN 1402-1544
Nyckelord
Organosolv lignin particles, Nanoparticles, Flotation reagent, Copper recovery
Nationell ämneskategori
Kemiska processer
Forskningsämne
Biokemisk processteknik
Identifikatorer
urn:nbn:se:ltu:diva-105140 (URN)978-91-8048-542-5 (ISBN)978-91-8048-543-2 (ISBN)
Disputation
2024-09-26, C305, Luleå University of Technology, Luleå, 09:00 (Engelska)
Opponent
Handledare
Tillgänglig från: 2024-04-17 Skapad: 2024-04-17 Senast uppdaterad: 2024-07-04Bibliografiskt granskad

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