Effects Of Surfactants And Metal Ions On Agglomeration Settlement Characteristics Of Fine Quartz Particles

Coal slurry mainly consisted oxide minerals,clay minerals,sulfide minerals and sulphate minerals,etc.Quartz,kaolinite and montmorillonite accounted for more than 60%of the total mineral content.These minerals had strong hydrophilicity,which made coal slurry was difficultied to settle down and clarified.The paper choosed fine quartz particles as the research object.In order to investigate the effects and mechanisms on aggregation settlement of fine quartz particles by using different surfactants and metal ions.The determining aggregation settlement,Zeta potential,infrared spectral analysis and molecular dynamics simulation were carried out.The research could provide the selection of coal slurry treatment reagents and the basis for technical development.The aggregation settlement experiments of fine quartz particles by quaternary ammonium salt such as dodecyl trimethyl ammonium chloride?1231?,tetradecyl trimethyl ammonium chloride?1431?,hexadecyl trimethyl ammonium chloride?1631?and octadecyl trimethyl ammonium chloride?1831?were carried out.The results showed that quaternary ammonium salt had physical adsorption on the surface of quartz.High concentration of 1231(?8×10^-4 mol/L)could improve hydrophobic aggregation of quartz.1431 was very effective on hydrophobic aggregation of quartz under the concentration between 1×10^-4 mol/L and 16×10^-4mol/L.1631 and 1831 were very effective on hydrophobic aggregation of quartz under low concentration(?2×10^-4 mol/L).1231 had gone worse with increasing the p H in solution.The change of p H in solution had little effect on 1431,1631and 1831.Ca²⁺and Mg²⁺had little effect on aggregation settlement of fine quartz particles.Al³⁺and Fe³⁺could promote fine quartz partucles to settle down.The sedimentation rate of quartz was increased and Zeta potential of quartz moved in the forward direction obviously with the concentration increased of Al³⁺and Fe³⁺.Al³⁺was beneficial to the settlement of quartz when the p H was 5.Fe³⁺was beneficial to the settlement of quartz when the p H was 3 to 10.Increasing the p H of the solution may cause the Zeta potential of quartz particles to move in a negative direction.The higher the p H value was,the more obvious the trend of Zeta potential of quartz particles moved to the negative direction.Salicylhydroxamic acid and benzohydroxamic acid didn't clarify settlement of fine quartz particles under the individual action.They had little effect on Zeta potential of quartz particles.When the value of p H was 11,salicylhydroxamic acid and benzohydroxamic acid with Ca²⁺and Mg²⁺could promote the settlement of fine quartz particles.Salicylhydroxamic acid and benzohydroxamic acid with Al³⁺couldn't prove the settlement of fine quartz particles.When the value of p H was3,salicylhydroxamic acid and benzohydroxamic acid with Fe³⁺could promote the settlement of fine quartz particles.The molecular dynamics simulation showed that quaternary ammonium salt surfactants could adsorb on the quartz surface.With increasing the length of the carbon chain,the stronger adsorption was.Salicylhydroxamic acid and benzohydroxamic acid had weak adsorption on the surface of quartz,and the adsorption behavior was not easy to occur.The results of molecular dynamics simulation coincide with the results of sedimentation experiments.It showed that molecular dynamics simulation could be used to study the mechanisms on agglomeration settlement of fine quartz particles,so it could provide theoretical support for the design and selection of new surfactants.