Preparation Of Functionalized Hydrophobic Nanoparticles And Their Flotation Characteristics To The Low Rank Coal

In this paper,functionalized hydrophobic nanoparticles with high hydrophobicity was prepared as the collector of low-rank coals,which is based on the characteristics of rich oxygen-containing groups,high porosity and poor hydrophobicity on the surface of low-rank coals.Collecting efficiency and selcetivity of hydrophobic nanoparticles were improved in the case of surface modification using suitable oxygen-containing functional groups.The super hydrophobicity of nanoparticles was utilized to modify the roughness of coal surface,leading to the improved hydrophobicity of coal particles.The selectivity of nanoparticles was enhanced by the addition of specific oxygen-containing groups.There are six types of functionalized hydrophobic nanoparticles were prepared with the various of types and dosages of SDS,CTAB(Emulsifier),MATE and AA(Functional monomer)using emulsion polymerization method.The size of functionalized hydrophobic nanoparticles decreases gradually with the increasing dosages of emulsifier.The potential of functionalized hydrophobic nanoparticles increases with the increase of emulsifier.The size,potential and oxygen content of functionalized hydrophobic nanoparticles were changed with the types of functional monomers.For a functional monomer,the oxygen content of functionalized hydrophobic nanoparticle increased gradually with the increasing dosages of functional monomer while the potential and size of functionalized hydrophobic nanoparticle didn't show an significant change.The experimental sample belongs to the coal with low ash content,high volatile content,low sulfur content and the contact angle of 49.3 °.It was found that the functionalized hydrophobic nanoparticles had a better effect on the low-rank coals flotation.The flotation recovery is 76.68% with functionalized hydrophobic nanoparticles of 40 mL(Mass concentration is 12kg/t)that was synthetized by 50 mg of CTAB emulsifier and 0.71 mL of functional monomer.Under the same mass concentration,the flotaiton recovery is 45.03% using diesel as collector.The mechanism for the interaction between hydrophobic nanoparticles and low-rank coals was investigated by the measurements of contact angle,FTIR and SEM.The hydrophobicity of low-rank coal was improved significantly with the additon of anionic/Cationic functionalized hydrophobic nanoparticle and thus the improved contact angle.The absorption peak of benzene was enhanced obviouslyafter the treament with functionalized hydrophobic nanoparticle.It indicated that functionalized hydrophobic nanoparticle adsorbed on the surface of low-rank coals.Both of hydrophilic absorption peaks(Hydroxyl group,Carboxyl group)and hydrophobic absorption peaks showed an increase with the addition of functionalized hydrophobic nanoparticle.However,the hydrophobic effect was more significant,which resulted in an improved hydrophobicity of coal.The results of SEM showed that a large number of nanoparticles attached on the surface of low-rank coals,leading to the improvement of surface roughness and further improve the hydrophobicity of low-rank coals.