Thiol-Silylated Cellulose Nanocrystals as Selective Biodepressants in Froth Flotation

The extraction of various minerals is commonly conducted through froth flotation, which is a versatile separation method in mineral processing. In froth flotation, depressants are employed to improve the flotation selectivity by modifying the wettability of the minerals and reducing their natural or induced floatability. However, the environmental impact of many current flotation chemicals poses a challenge to the sustainability and selectivity of the ore beneficiation processes. To mitigate this issue, cellulose, particularly nanocelluloses, has been explored as a potential alternative to promote sustainable mineral processing. This study focused on silylated cellulose nanocrystals (CNCs) as biodepressants for sulfide minerals in froth flotation. CNCs containing thiol silane groups or bifunctional CNCs containing both thiol and propyl silanes were synthesized using an aqueous silylation reaction, and their performance in the flotation of chalcopyrite and pyrite was investigated in the presence of a sodium isobutyl xanthate collector. The results showed that the modified CNCs exhibited preferential interaction between chalcopyrite, and the flotation recovery of chalcopyrite decreased from similar to 76% to similar to 24% in the presence of thiol-grafted CNCs at pH 6, while the pyrite recovery decreased only from similar to 82% to similar to 75%, indicating the efficient selectivity of thiol-silylated CNCs toward chalcopyrite depression.

Automated summary

This study focused on silylated cellulose nanocrystals as biodepressants for sulfide minerals in froth flotation. The results showed that the thiol-silylated nanocrystals exhibited efficient suppression of chalcopyrite.