Browsing by Author "Saeed, Mohazzam"

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Quantifying the degree of selectivity in a Flocculation-Flotation process of LiCoO2 and graphite using scanning electron microscopy and image processing analysis
(2024-04) Rinne, Tommi; Saeed, Mohazzam; Serna-Guerrero, Rodrigo
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
This research article studies selective flocculation as a means for improving flotation of lithium-ion battery active materials using mixtures of pure LiCoO2 (LCO) and graphite. Scanning electron microscopy (SEM) combined with image analysis via density-based spatial clustering of applications with noise (DBSCAN) is presented as a novel method to quantitatively determine the degree of selectivity in a process that applies selective flocculation as a conditioning stage for froth flotation. SEM was shown to provide visual proof of flocculated particles, even in dried froth samples. Under optimal flocculant concentration of 10 g/t only a few flocs were detected in the froth concentrate, suggesting that heteroflocculation of LCO and graphite was minimized under said conditions. Using a flocculant concentration in excess (50 g/t) resulted in multiple flocculated LCO particles within the froth, indicating loss of flocculation selectivity. These results were corroborated by batch flotation experiments, which showed that treating the pulp with 10 g/t flocculant concentration yielded a graphite froth product at a grade of 98.2 %, compared to 98.1 % recovered from a non-flocculated pulp. An excess flocculant concentration led to a drastic reduction in graphite grade. Similar graphite recoveries were observed in all flotation experiments, indicating that the reduced graphite grade with excess flocculant was a result of hydrophobic heteroflocs carrying entrapped LCO to the froth. Proper pH control throughout the experiment prevented a negative influence of flocculation on the kinetics of graphite recovery, which had been reported in earlier research. The results suggest that selective flocculation is a potential method for improving the separation efficiency of graphite from Li-ion battery waste, and that SEM/DBSCAN can be applied for characterization of selectivity in combined flocculation-flotation processes.
A study on optimization of graphite separation in lithium-ion battery waste recycling via froth flotation and selective flocculation: A response surface methodology approach
(2024-08-29) Esmaeilzadeh Dilmaghani, Sevda
Kemian tekniikan korkeakoulu | Master's thesis
The growing demand for lithium-ion batteries (LIBs) necessitates effective recycling methods to recover valuable materials and mitigate environmental impact. This study investigates the optimization of graphite separation from LIB waste using froth flotation and selective flocculation. Flotation is utilized due to the natural hydrophobicity of graphite compared to the hydrophilic nature of cathode materials, making it a suitable method for separation. Selective flocculation is explored to enhance the efficiency of this process by promoting the aggregation of target particles. Key flotation parameters, including solid content, impeller tip speed, conditioning time, and flocculant dosage, were systematically varied and analyzed using a Response Surface Methodology (RSM) approach. Results indicated that employing ultrafine cathode particles (<10 µm) in the model black mass feed achieved a graphite concentrate grade of 98.63% with a recovery rate of 71.98% in a single-stage flotation process. Among the parameters studied, solid content was found to have the most significant impact on graphite grade, while impeller tip speed and flocculant dosage most influenced graphite recovery. Through response optimization, it was determined that optimal conditions include a solid content of 20 g/L, a conditioning time of 13 min, and an impeller tip speed of 1040 rpm, resulting in a graphite grade of 99.02% and a graphite recovery of 74.54%. This study highlights the potential of combining froth flotation with RSM to enhance the efficiency and effectiveness of graphite separation in LIB recycling processes. Future research should explore alternative pH levels, flocculants, and multi-stage flotation processes to further improve separation performance.