新型纳米粒子捕收剂强化低阶煤浮选机理

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

低阶煤表面含有丰富的含氧官能团、疏水性差,常规油类捕收剂难以吸附铺展,导致浮选效率低、药剂消耗量大,严重制约了细粒低阶煤的回收利用。采用四氢呋喃基团功能化的聚苯乙烯纳米粒子(TFPNs)作为捕收剂强化低阶煤浮选,借助Zeta电位仪、透射电镜(TEM)和X射线光电子能谱(XPS)分析了纳米粒子特性,比较了TFPNs、聚苯乙烯纳米粒子(PNs)和柴油(DO)的浮选性能,利用红外光谱仪(FTIR)、扫描电镜(SEM)和接触角测量仪研究了TFPNs强化低阶煤浮选的作用机理。纳米粒子特性分析表明:TFPNs呈球形且粒径在50~138 nm;随着乳化剂用量增加,TFPNs的粒径逐渐减小而Zeta电位逐渐增大,表面功能化程度与功能化单体用量呈正比。浮选试验结果证明:3种捕收剂的浮选回收率大小关系为TFPNs>PNs>DO;TFPNs的粒径越小,浮选回收率越高;随表面功能化程度升高,浮选回收率先上升后下降;四氢呋喃基团功能化能够增强PNs捕收性能,最佳的表面功能化程度在5.78%~6.56%。作用机理研究发现:TFPNs通过四氢呋喃基团与低阶煤表面含氧官能团之间形成氢键而吸附于低阶煤表面,提高低阶煤表面的疏水性和粗糙度,缩短气泡-颗粒诱导时间,从而提高低阶煤的浮选回收率。因此纳米粒子捕收剂为低阶煤浮选新型高效药剂设计开发提供借鉴。

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.