柴油对浮选泡沫稳定性影响的试验研究
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摘要
泡沫稳定性是影响浮选过程效率的重要参数之一。为了探究柴油对浮选泡沫稳定性的影响,借助泡沫扫描分析仪(FOAMSCAN)研究了气液两相体系下不同浓度的柴油与体积分数20×10-6的甲基异丁基甲醇(MIBC)混合溶液的起泡能力与泡沫稳定性,采用动态液膜分析装置分析了泡沫间液膜的最终状态,进一步明晰了柴油对泡沫稳定性的影响机制,并通过细粒煤浮选及气液固三相泡沫稳定性试验探讨了柴油对实际浮选体系泡沫性质及浮选效果的影响。气液两相体系泡沫稳定性试验表明,随着柴油浓度的增加,溶液起泡能力和泡沫稳定性逐渐降低。泡沫间液膜测试结果说明,柴油浓度加大使得泡沫间液膜由最终的平衡状态转为破裂状态,液膜稳定性变差,气泡更容易兼并甚至破裂,该结论与气液两相泡沫稳定性试验结果保持一致。浮选结果表明,柴油用量较低时,随着柴油浓度增加,最大泡沫层高度和半衰期逐渐增大,浮选精煤产率也随之增大,这主要是由于柴油改善煤样表面疏水性以及细粒煤的稳泡作用所致;但当柴油用量增加到一定浓度后,最大泡沫层高度和泡沫半衰期减小,浮选精煤产率减小,一方面,柴油油滴进入泡沫间液膜中,在范德华力等力的驱使下,泡沫间的液膜逐渐薄化直至形成经典的油滴架桥现象,最终导致气泡兼并甚至破裂,另一方面,柴油油滴竞争吸附起泡剂分子,使得气液界面的起泡剂浓度降低,从而导致泡沫稳定性降低,柴油具有一定的消泡作用。
Foam stability is an important parameter affecting the flotation efficiency.To investigate the effect of diesel on foam stability,the foaming ability and foam stability of mixed solution of different diesel concentrations with 20 ×10-6 methyl isobutyl carbinol( MIBC) solution were explored by foam scanning analyzer( FOAMSCAN).The final status of liquid film between foams was analyzed by dynamic liquid film apparatus,and the effect of diesel on foam stability was further clarified.Moreover,the effect of diesel on foam characteristics and flotation performance were discussed through fine coal flotation tests and gas-liquid-solid three-phase foam stability tests.The foam stability tests of gas-liquid two-phase system showed that the foaming ability and foam stability gradually decreased with the increase of diesel concentration.The results of liquid film tests showed that the final liquid film changed from the equilibrium state to the rupture state,and became more and more unstable with the increase of diesel concentration,which eventually made the bubble more likely to coalesce or even rupture.This conclusion was consistent with the results of gas-liquid two-phase foam stability tests.In addition,the flotation results showed that the maximum froth height and half-life increased with the increase of diesel concentration when the concentration was lower,and the flotation clean coal yield increased as well,which was mainly due to the improvement of hydrophobicity on the coal surface and the effect of stabilizing foam of fine coal.However,the maximum froth height and half-life gradually decreased,and the flotation clean coal yield also decreased when the concentration exceeded a certain concentration. This is because,on the one hand,diesel invaded into the interfoam film and the film thinned driven by van der Waals force and other forces until the formation of classic oil droplet bridging phenomenon,eventually leading to the bubbles rupture.On the other hand,the diesel oil droplets competitively adsorbed frother molecules,so that the concentration of frother at the gas-liquid interface decreased,making foams less stable.Therefore,diesel has a certain defoaming effect on foam stability in flotation.
Foam stability is an important parameter affecting the flotation efficiency.To investigate the effect of diesel on foam stability,the foaming ability and foam stability of mixed solution of different diesel concentrations with 20 ×10-6 methyl isobutyl carbinol( MIBC) solution were explored by foam scanning analyzer( FOAMSCAN).The final status of liquid film between foams was analyzed by dynamic liquid film apparatus,and the effect of diesel on foam stability was further clarified.Moreover,the effect of diesel on foam characteristics and flotation performance were discussed through fine coal flotation tests and gas-liquid-solid three-phase foam stability tests.The foam stability tests of gas-liquid two-phase system showed that the foaming ability and foam stability gradually decreased with the increase of diesel concentration.The results of liquid film tests showed that the final liquid film changed from the equilibrium state to the rupture state,and became more and more unstable with the increase of diesel concentration,which eventually made the bubble more likely to coalesce or even rupture.This conclusion was consistent with the results of gas-liquid two-phase foam stability tests.In addition,the flotation results showed that the maximum froth height and half-life increased with the increase of diesel concentration when the concentration was lower,and the flotation clean coal yield increased as well,which was mainly due to the improvement of hydrophobicity on the coal surface and the effect of stabilizing foam of fine coal.However,the maximum froth height and half-life gradually decreased,and the flotation clean coal yield also decreased when the concentration exceeded a certain concentration. This is because,on the one hand,diesel invaded into the interfoam film and the film thinned driven by van der Waals force and other forces until the formation of classic oil droplet bridging phenomenon,eventually leading to the bubbles rupture.On the other hand,the diesel oil droplets competitively adsorbed frother molecules,so that the concentration of frother at the gas-liquid interface decreased,making foams less stable.Therefore,diesel has a certain defoaming effect on foam stability in flotation.
引文
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[12]冉进财,李国胜,曹亦俊,等.无机盐阳离子对粉煤灰浮选泡沫稳定性的影响研究[J].煤炭学报,2015,40(3):646-651.RAN Jincai,LI Guosheng,CAO Yijun,et al. Influence of inorganic salt on flotation froth stability of coal fly ash[J]. Journal of China Coal Society,2015,40(3):646-651.
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[15]朱晓园,梅光军,于明明.新型阳离子捕收剂MZ-3的浮选与消泡行为研究[J].金属矿山,2016,45(1):69-71.ZHU Xiaoyuan,MEI Guangjun,YU Mingming.Study on froth characteristics and flotation performance of a new cationic collector MZ-3[J].Metal Mine,2016,45(1):69-71.
[16]李国胜,刘炯天,曹亦俊,等.粉煤灰中难浮未燃炭的柱式浮选脱除试验研究[J].煤炭学报,2013,38(2):308-313.LI Guosheng,LIU Jiongtian,CAO Yijun,et al. Experimental study on removal of unburned carbon from coal fly ash using flotation column[J].Journal of China Coal Society,2013,38(2):308-313.
[17] PARK Hangil,WANG Liguang.Determination of the concentration of MIBC in coking coal flotation[J]. Minerals Engineering,2018,127:74-80.
[18] XING Yaowen,GUI Xiahui,CAO Yijun,et al. Effect of compound collector and blending frother on froth stability and flotation performance of oxidized coal[J]. Powder Technology,2017,305:166-173.
[19] OSEI-BONSU Kofi,SHOKRI Nima,GRASSIA Paul.Foam stability in the presence and absence of hydrocarbons:From bubble-to bulkscale[J]. Colloids&Surfaces A Physicochemical&Engineering Aspects,2015,481:514-526.
[20] PAN Lei,JUNG Sunghwan,YOON Roe-Hoan.A fundamental study on the role of collector in the kinetics of bubble-particle interaction[J]. International Journal of Mineral Processing,2012,106-109(2):37-41.
[21]李国胜.浮选泡沫的稳定性调控及粉煤灰脱炭研究[D].徐州:中国矿业大学,2013:17-18.LI Guosheng. Regulation of flotation froth stability and removal of unburned-carbon from coal fly ash[D]. Xuzhou:China University of Mining and Technology,2013:17-18.
[22]燕永利,王瑶,山城,等.油滴作用下的气泡液膜破裂机理研究进展[J].日用化学工业,2013,43(4):303-308.YAN Yongli,WANG Yao,SHAN Cheng,et al.Progress in research work with respect to the mechanism for foam film rupture by action of oil droplets[J]. China Surfactant Detergent&Cosmetics,2013,43(4):303-308.
[23]桂夏辉,邢耀文,杨自立,等.煤泥浮选过程强化之六———浮选流体动力学与界面调控协同强化篇[J].选煤技术,2017(6):82-86.GUI Xiahui,XING Yaowen,YANG Zili,et al. Fine coal flotation process intensification—Part 6:Hydrodynamics-interfacial conditioning synergistic enhancement[J]. Coal Preparation Technology,2017(6):82-86.
[24] GAO Fengfeng,LIU Guokui,YUAN Shiling. The effect of betaine on the foam stability:Molecular Simulation[J]. Applied Surface Science,2017,407:156-161.
[25] RAFATI Roozbeh,OLUDARA Opeyemi Kehinde,HADDAD Amin Sharifi,et al.Experimental investigation of emulsified oil dispersion on bulk foam stability[J]. Colloids&Surfaces A Physicochemical&Engineering Aspects,2018,554:110-121.
[26] DENKOV Nikalai D.Mechanisms of foam destruction by oil-based antifoams[J].Langmuir,2004,20(22):9463-9505.
[2]杨润全,王怀法.宽粒级煤浮选机流场数值模拟研究[J].煤炭学报,2013,38(4):657-661.YANG Runquan,WANG Huaifa.A numerical simulation study on the flow field of wide size fraction coal flotation machine[J]. Journal of China Coal Society,2013,38(4):657-661.
[3]桂夏辉,刘炯天,陶秀祥,等.难浮煤泥浮选速率试验研究[J].煤炭学报,2011,36(11):1895-1900.GUI Xiahui,LIU Jiongtian,TAO Xiuxiang,et al. Studies on flotation rate of a hard to float fine coal[J]. Journal of China Coal Society,2011,36(11):1895-1900.
[4]冯其明,穆枭,张国范,等.浮选生产过程中的泡沫及消泡技术[J].矿产保护与利用,2005(4):31-35.FENG Qiming,MU Xiao,ZHANG Guofan,et al. Foaming and defoaming technology in flotation processes[J].Conservation&Utilization of Mineral Resources,2005(4):31-35.
[5] WANG Bo,PENG Yongjun.The effect of saline water on mineral flotation-a critical review[J]. Minerals Engineering,2014,66-68:13-24.
[6]付亚峰,印万忠,姚金,等.绿泥石颗粒效应对泡沫稳定性的影响[J].中南大学学报(自然科学版),2018,49(8):1857-1862.FU Yafeng,YIN Wanzhong,YAO Jin,et al.Study on stability of flotation foam influenced by particle effect of chlorite[J]. Journal of Central South University(Science and Technology),2018,49(8):1857-1862.
[7]郭建伟,苏壮飞,李正明,等.降低浮选泡沫稳定性的探索试验[J].选煤技术,2016(4):10-14.GUO Jianwei,SU Zhuangfei,LI Zhengming,et al.Exploratory experiment on reduction of stability of flotation froth[J]. Coal Preparation Technology,2016(4):10-14.
[8]柳泉洲,陶秀祥,何环,等.浮选油泡稳定性试验研究[J].煤炭技术,2016,35(10):303-305.LIU Quanzhou,TAO Xiuxiang,HE Huan,et al. Experimental study on stability of oil bubbles of flotation[J]. Coal Technology,2016,35(10):303-305.
[9]刘德生,陈小榆,周承富.温度对泡沫稳定性的影响[J].钻井液与完井液,2006,23(4):10-12,86.LIU Desheng,CHEN Xiaoyu,ZHOU Chengfu. Effects of temperature on the stability of foam[J]. Drilling Fluid Completion Fluid,2006,23(4):10-12,86.
[10] LI Xueliang,SHAW Ryan,STEVENSON Paul. Effect of humidity on dynamic foam stability[J].International Journal of Mineral Processing,2010,94(1-2):14-19.
[11]曲彦平,杜鹤桂,葛利俊.表面粘度对泡沫稳定性的影响[J].沈阳工业大学学报,2002,24(4):283-286.QU Yanping,DU Hegui,GE Lijun. Effects of surface viscosity on foam stability[J]. Journal of Shenyang University of Technology,2002,24(4):283-286.
[12]冉进财,李国胜,曹亦俊,等.无机盐阳离子对粉煤灰浮选泡沫稳定性的影响研究[J].煤炭学报,2015,40(3):646-651.RAN Jincai,LI Guosheng,CAO Yijun,et al. Influence of inorganic salt on flotation froth stability of coal fly ash[J]. Journal of China Coal Society,2015,40(3):646-651.
[13] ZHANG Hui,MILLER Clarence A,GARRETT Peter R,et al.Defoaming effect of calcium soap[J]. Journal of Colloid&Interface Science,2004,279(2):539-547.
[14] HU Nan,LI Yanfeng,WU Zhaoliang,et al.Foams stabilization by silica nanoparticle with cationic and anionic surfactants in column flotation:Effects of particle size[J].Journal of the Taiwan Institute of Chemical Engineers,2018,88:62-69.
[15]朱晓园,梅光军,于明明.新型阳离子捕收剂MZ-3的浮选与消泡行为研究[J].金属矿山,2016,45(1):69-71.ZHU Xiaoyuan,MEI Guangjun,YU Mingming.Study on froth characteristics and flotation performance of a new cationic collector MZ-3[J].Metal Mine,2016,45(1):69-71.
[16]李国胜,刘炯天,曹亦俊,等.粉煤灰中难浮未燃炭的柱式浮选脱除试验研究[J].煤炭学报,2013,38(2):308-313.LI Guosheng,LIU Jiongtian,CAO Yijun,et al. Experimental study on removal of unburned carbon from coal fly ash using flotation column[J].Journal of China Coal Society,2013,38(2):308-313.
[17] PARK Hangil,WANG Liguang.Determination of the concentration of MIBC in coking coal flotation[J]. Minerals Engineering,2018,127:74-80.
[18] XING Yaowen,GUI Xiahui,CAO Yijun,et al. Effect of compound collector and blending frother on froth stability and flotation performance of oxidized coal[J]. Powder Technology,2017,305:166-173.
[19] OSEI-BONSU Kofi,SHOKRI Nima,GRASSIA Paul.Foam stability in the presence and absence of hydrocarbons:From bubble-to bulkscale[J]. Colloids&Surfaces A Physicochemical&Engineering Aspects,2015,481:514-526.
[20] PAN Lei,JUNG Sunghwan,YOON Roe-Hoan.A fundamental study on the role of collector in the kinetics of bubble-particle interaction[J]. International Journal of Mineral Processing,2012,106-109(2):37-41.
[21]李国胜.浮选泡沫的稳定性调控及粉煤灰脱炭研究[D].徐州:中国矿业大学,2013:17-18.LI Guosheng. Regulation of flotation froth stability and removal of unburned-carbon from coal fly ash[D]. Xuzhou:China University of Mining and Technology,2013:17-18.
[22]燕永利,王瑶,山城,等.油滴作用下的气泡液膜破裂机理研究进展[J].日用化学工业,2013,43(4):303-308.YAN Yongli,WANG Yao,SHAN Cheng,et al.Progress in research work with respect to the mechanism for foam film rupture by action of oil droplets[J]. China Surfactant Detergent&Cosmetics,2013,43(4):303-308.
[23]桂夏辉,邢耀文,杨自立,等.煤泥浮选过程强化之六———浮选流体动力学与界面调控协同强化篇[J].选煤技术,2017(6):82-86.GUI Xiahui,XING Yaowen,YANG Zili,et al. Fine coal flotation process intensification—Part 6:Hydrodynamics-interfacial conditioning synergistic enhancement[J]. Coal Preparation Technology,2017(6):82-86.
[24] GAO Fengfeng,LIU Guokui,YUAN Shiling. The effect of betaine on the foam stability:Molecular Simulation[J]. Applied Surface Science,2017,407:156-161.
[25] RAFATI Roozbeh,OLUDARA Opeyemi Kehinde,HADDAD Amin Sharifi,et al.Experimental investigation of emulsified oil dispersion on bulk foam stability[J]. Colloids&Surfaces A Physicochemical&Engineering Aspects,2018,554:110-121.
[26] DENKOV Nikalai D.Mechanisms of foam destruction by oil-based antifoams[J].Langmuir,2004,20(22):9463-9505.