Mechanism of enhancing low rank coal flotation using nanoparticles as a novel collector

The surface of LRC contains rich oxygen-containing functional groups with poor hydrophobicity,which makes it difficult for conventional oil collectors to absorb and spread.The low flotation efficiency and high reagents consumption seriously restricts the recovery and utilization of LRC fines.Tetrahydrofuran functionalized polystyrene nanoparticles (TFPNs) was used as collector for LRC flotation.The Zeta potential analyzer,TEM and XPS were first used to analyze properties of TFPNs.Then,the flotation properties of TFPNs,polystyrene nanoparticles (PNs) and diesel oil (DO) were compared.Finally,infrared spectrometer (FTIR),scanning electron microscope (SEM) and contact angle measuring instrument were used to study the enhancement mechanism of TFPNS on LRC flotation.The nanoparticles’properties showed that TFPNs was spherical and the particle size ranged from 50 nm to 138 nm;with the increase of emulsifier dosage,the particle size of TFPNs decreased while its zeta potential increased,and the degree of surface functionalization was proportional to the amount of functional monomer.The flotation results indicated that the order of flotation recovery of the three collectors was TFPNs>PNs>DO;the smaller the particle size of TFPNs,the higher the flotation recovery;with the increase of surface functionalization,the flotation recovery first increased and then decreased;Tetrahydrofuran group functionalization improved the collection performance of PNs,and the best surface functionalization range was 5.78%-6.56%.The mechanism was found that the hydrophobicity and roughness of LRC surface were improved due to the adsorption of TFPNs by forming hydrogen bonds between tetrahydrofuran groups and oxygen-containing functional groups,which shortened the induction time between bubbles and coal particles and improved the flotation recovery of low rank coal.Therefore,the nanoparticle collector provides a new way for the design and development of novel efficient reagents for low rank coal flotation.