Flotation and adsorption of novel Gemini decyl-bishydroxamic acid on bastnaesite:Experiments and density functional theory calculations

Rare earth element is an important strategic metal,but the supply of high purity rare earth ores is growing slowly,which is in sharp contradiction with the rapidly growing demand.Froth flotation has been confirmed to be an effective method to separate bastnaesite from its gangue minerls.However,the traditional collectors are facing serious problems in flotation separation of minerals,requiring the addition of excess depressant and regulator in the flotation process.Herein,we proposed and synthesized novel Gemini hydroxamic acids Octyl-bishydroxamic acid(OTBHA),Decyl-bishydroxamic acid(DCBHA)and Dodecyl-bishydroxamic acid(DDBHA)as the collectors in bastnaesite-barite flotation system.The effect of different carbon chain lengths on the molecular properties were explored by density functional theory(DFT)calculations.DCBHA possessed a stronger reactivity compared with OCBHA and DDBHA.The flotation results verified the consistency of the computational calculation about the performance prediction of Gemini hydroxamic acids.Compared with OCBHA and DDBHA,DCBHA displayed superior collecting affinity toward bastnaesite,and did not float barite.Zeta potential results showed that the presence of DCBHA increased the potential of bastnaesite,while it had almost no effect on barite,indicating DCBHA had a stronger affinity for bastnaesite.Then,Fourier transform infrared(FTIR)and X-ray photoelectron spectroscopy(XPS)analyses indicated that the adsorption mechanism was due to two hydroxamate groups of DCBHA co-anchored on bastnaesite surface by forming five-membered hydroxamic―(O―O)―Ce complexes.In addition,atomic force microscopy(AFM)clearly observed that DCBHA uniformly aggregated on bastnaesite surface,which increased surface contact angle and improved the hydrophobicity of bastnaesite.

Microscale insights into the influence of grinding media on spodumene micro-flotation using mixed anionic/cationic collectors

Here,the influence of grinding media with different shapes on the flotation performance of spodumene and its potential mechanism from microscale insights was investigated using a single mineral flotation experiment,X-ray diffraction(XRD)test,scanning electron microscopy combined with energy dispersive spectrometry(SEM-EDS),atomic force microscope(AFM)and X-ray photoelectron spectroscopy(XPS).The flotation data indicated that under anionic/cationic(sodium oleate(NaOL)/DDA)collectors system,the rod milled spodumene has a higher floatability than ball milled ones.XRD results confirmed that rod medium makes spodumene exposed more{110}and{100}planes,while ball medium makes spodumene exposed more{010}planes.The typical anisotropic surface of spodumene makes the surface of rod milled spodumene possess more Al sites,further confirmed by SEM-EDS and XPS results.Additionally,it was found that the rod milled spodumene presents a larger value of elongation and flatness,which are parameters closely related to bubble adhesion.AFM analysis indicated that rod milled products have a rougher surface,while ball milled products have a smoother surface.Consequently,the rod medium enhanced the adsorption of NaOL/DDA on the spodumene surfaces.This work provides theoretical guidance for optimizing the separation of spodumene from the perspective of grinding.

An in situ ATR-FTIR study of mixed collectors BHA/DDA adsorption in ilmenite-titanaugite flotation system

This paper researched the enhanced flotation separation performance of ilmenite and titanaugite using the mixed collector benzhydroxamic acid/dodecylamine(BHA/DDA).The interface assembly mechanism was mainly investigated through in situ attenuated total reflectance Fourier transform infrared(ATRFTIR)spectroscopy combined with the two-dimensional correlation spectroscopy(2D-COS)and X-ray photoelectron spectroscopy(XPS).It has been found that BHA/DDA mixed collectors successfully separate ilmenite from titanaugite at a molar ratio of 8:1.Zeta potential experiments suggested that,in the presence of mixed collector system,the BHA-DDA complex adsorbed on the ilmenite surface via the chemically adsorbed BHA and the electrostatically adsorbed DDA,however,the complex adsorbed on the surface of titanaugite unstably.According to in situ ATR-FTIR combined with 2D-COS and XPS results,the interface assembly mechanism of BHA/DDA is summarized as:the function group of BHA molecules first binds to the metal sites on minerals to form bidentate ligand,then DDA co-adsorbed with BHA on the surface of minerals through hydrogen bonding.DDA may change the adsorption modes of some BHA on the ilmenite surface from four-membered ring to five-membered ring,while the modes on the titanaugite surface is true opposite.Finally,recommended adsorption configurations of the BHA/DDA complex on the two mineral surfaces are proposed.