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Molecular Dynamics Simulation Of The Adsorption Of Amine Flotation Agents On The Mica And Quartz Surface

Posted on:2017-04-02Degree:MasterType:Thesis
Country:ChinaCandidate:D SuFull Text:PDF
GTID:2321330542950502Subject:Inorganic Chemistry
Abstract/Summary:PDF Full Text Request
Collector play an extremely important role in the separation of finely ground valuable minerals from their associated gangue via flotation.As typical cationic collectors,amines have been widely applied in the flotation.With increasing computer power,computer simulation acts as a bridge between theory and experiments,which enables us to study the properties of molecules in terms of the structure and interaction at the microscopic level.As a complement to conventional experiments,molecular dynamics simulation,which describes inter and intra molecular interactions using force field,becomes a useful tool to study the adsorption of the surfactant/water on the solid surface.Molecular dynamics simulations have been performed for the study of interaction between cationic collectors with different alkyl chain lengths and the mica(001)surface.The calculated interaction energy between ammonium with different akyl chain lengths and the mica(001)surface reveal that collecting power of alkyl propyl ether ammonium for mica flotation is better than that of alkyl trimethyl ammonium,which match well with those experiments in the earlier work.Calculated results also show that the strength of collector-mineral surface interactions follows the order of alkyl dimethyl benzyl ammonium< N,N-dimethyl-alkyl ammonium<N-alkyl-1,3-diaminopropane,alkyl propyl ether ammonium and N-(3-aminopropyl)-alkylamide,indicating that the alkyl propyl ether ammonium,N-alkyl-1,3-diaminopropane and N-(3-aminopropyl)-alkylamide are more effective.The interaction between ammonium ions and the quartz(001)surface in the vacuum have been analyzed on the basis of molecular dynamics simulation using PCFF_phyllosilicates force field.The interaction energies of ammonium ions with different alkyl chain lengths on the quartz(001)surface are calculated.Results reveal that compared with N,N-dimethyl-alkyl ammonium 、 alkyl trimethyl ammonium and alkyl dimethyl benzyl ammonium,the adsorption energies of alkylammonium、N-alkyl-1,3-diaminopropane、alkyl propyl ether ammonium and N-(3-aminopropyl)-alkylamide are lower,indicating the stronger interaction between these ammonium ions and the quartz(001)surface.Therefore,alkylammonium、N-alkyl-1,3-diaminopropane、N-(3-aminopropyl)-alkylamide and alkyl propyl ether ammonium are much more effective collector in flotation.The MD simulation revealed that positively charged head group of ammonium ions can adsorb on the quartz surface via electrostatic bonding.Furthermore,the formation of hydrogen bonds between head groups H atoms and the surface oxygen atoms can enhance the interaction of alkylammonium、N-alkyl-1,3-diaminopropane、alkyl propyl ether ammonium and N-(3-aminopropyl)-alkylamide with the surface.The adsorption of butane-α,ω-bis(alkyl dimethyl ammonium)with different carbon chains on the mica and quartz(001)surface have been studied using molecular dynamics simulations.The relationship between structure and the adsorption performance of butane-α,ω-bis(alkyl dimethyl ammonium)has been discussed.The MD simulation indicate that the interation strength and adsorption behavior of the ammonium ion on the mica and quartz(001)surface are influenced by the structure of the N-containing polar head group of ammonium ions,irrespective of the carbon chain length.The results drawn from the computed interaction energies showed that butane-α,ω-bis(alkyl dimethyl ammonium)is more effective collectors for mica and quartz flotation,compare with alkyl trimethyl ammonium.Due to the steric effect,the head group H atoms of butane-α,ω-bis(alkyl dimethyl ammonium)cannot form hydrogen bonds with surface oxygen atoms.It is found that ammonium ions can form a parallel orientation relative to the mica and quartz surface,and the adsorption state of collector ion on the(001)surface is relatively instable.
Keywords/Search Tags:cationic collectors, mica, quartz, molecular dynamics simulation, interaction energy
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