Agglomeration Flotation Characteristics Of Micro-fine Spodumene And The Reaction Mechanism On Mineral's Surface

Spodumene commonly occurs in granitic pegmatite deposits.The ore is easy to be fine-grained and alternated due to weathering and alteration effect.Amount of micro-fine minerals particles are generated in crushing and grinding process.In flotation process,it is difficult to break the energy barrier between ore particles and bubbles in the flotation process due to its small mass,fine-grained and strong surface hydrophilicity.This makes it can't effectively adhere on the bubbles and thus difficult to recover.Moreover,spodumene,feldspar and quartz are belonging to aluminosilicate minerals and has similar crystal structure and surface properties.It is difficult to separate them through flotation method.At present,the effective separation of micro-fine spodumene has become a common technical problem in the field of mineral processing.In order to provide a new technical means and theoretical basis for the efficient flotation recovery of micro-fine spodumene,the agglomeration flotation characteristics and mineral surface reaction mechanism of micro-fine spodumene from the perspective of improving the apparent particle size and floatability of micro-fine particles were investigated in this paper.Firstly,by using Material Studio software,the crystal chemistry and surface properties of spodumene minerals are systematically studied by the simulation calculation.Furthermore,the flotation behavior and kinetics of micro-fine spodumene are studied by micro-flotation,turbidity test,laser particle size analysis and microscope observation.The surface hydration model and the model of calcium ions adsorption on spodumene are constructed.The surface reaction mechanism of spodumene on agglomeration flotation was investigated according to the quantum chemistry and flotation solution chemistry principles.Finally,the laboratory test and industrial test on agglomeration flotation were carried out.The crystal chemistry and dissociation characteristics of spodumene,feldspar and quartz were researched.There are three chemical bonds in spodumene crystal:Li-O,Al-O and Si-O.Track hybridization of Li-O bond is not obvious.Li-O bond has weak covalency and bonding strength.Al-O bond has obvious track hybridization and strong bonding strength.Si-O bond has strongest covalency and intense track hybridization.Under external stress,spodumene,feldspar and quartz cleave and crack in the direction Li-O,Al-O and Si-O of parallel network with weak chemical bond strength.The cleave type is fair cleavage,perfect cleavage and very imperfect cleavage.Spodumene and feldspar is easy over grinding and sludge under the case of Sufficient monomer dissociation.The total fracture chemical bond density of the sum and product of chemical bond and fracture chemical bond density is used as the judgment basis for the probability of dissociation surface formation.The probability order of the dissociation surface formation of each mineral is:spodumene?110?>?010?>?100?,feldspar?001?>?010?>?110?,quartz?101?>?100?>?001?.Because the density of metal atom,the ratio of Al-O breaking bond and the unsaturation of spodumene are the highest.The floatability of spodumene is better than that of feldspar.The flotation behavior of micro-fine spodumene on agglomeration flotation are studied.The results show that-19?m micro-fine spodumene has the worst floatability and strong surface wettability,which is difficult to recover in conventional flotation.Micro-fine spodumene can be well recovered in agglomeration flotation process.However,the effect of recovery is affected by the shear strength of the fluid and the interface reaction conditions.When the stirring strength is 1600r/min and the stirring time is 18min,benzyl arsenate is used as the collector and calcium ion is used as the activator,adjusting the pulp p H to 9?10,which can achieve the agglomeration flotation recovery of micro-fine spodumene.While,under the condition,feldspar and quartz are not clear obvious agglomerated,which cannot be recovered in the flotation process.According to this,the growth model of micro-fine spodumene agglomerates is established.Besides,the relationship between the degree of agglomerations and the flotation rate is also established.The agglomerations of spodumene particles first occur in the intermediate size of-13+8?m,then in the super micro-fine size of-8?m,and finally in the coarse size of-19+13?m.The agglomerations have undergone four stages:agglomerations formation,growth,bridging to fragmentation.The particle size has gradually shifted from the initial two peak type to the single peak type.The flotation rate of spodumene increased from 0 to 0.0213s^-1.But excessive shear strength also affects the stability of coarse-grained agglomerations,and then reduces the degree of agglomeration and flotation rate of particles.Even so,it has little on flotation recovery rate,which can still be kept at a high level.The surface reaction mechanism of spodumene flotation was investigated.The co-adsorption model of collector and calcium ions on mineral hydration surface in solution environment was established.The results of poor flotation effect of spodumene and the difference of interface reaction in different systems were analyzed,by researching the surface reaction mechanism of spodumene on agglomeration flotation.The results show that the surface of spodumene has a strong hydrophilicity,and water molecules can be hybridized into bonds by its O 2p orbital and the 3s and 3p orbital of Al atoms on the surface of spodumene.The adsorption energy is-231.52 KJ/mol,and the hydration is strongly.Calcium ion is a common activated ion in spodumene flotation,its hydrolytic component adsorbed on the surface of mineral hydration in the form of metal ion hydrate,and the highest adsorption strength is Ca?OH?⁺and Ca?OH?_2?aq?,the Ca²⁺is lowest.After mineral surface hydration,water molecules have space steric effect on collector,which reduces the action strength of collector,and the adsorption energy of benzyl arsenate on spodumene surface from-190.83 k J/mol on vacuum surface to-63.51 k J/mol on the hydration surface.The addition of calcium ion can greatly improve the adsorption effect of the collector,and the activation effect of hydrolysis component Ca?OH?⁺is the best.Under the action of Ca?OH?⁺,the adsorption strength of benzyl arsenate on spodumene surface is the highest,the adsorption energy is-215.32 k J/mol,the adsorption strength on feldspar surface is low,and the adsorption energy is-145.82k J/mol.Using calcium ion as activator,adjusting pulp p H to 9-10 and adjusting hydrolytic component Ca?OH?⁺concentration,which will be more conducive to agglomeration flotation recovery of micro-fine spodumene and separation from feldspar.The results show that the spodumene concentrate containing Li₂O 5.77%and a recovery of 75.24%is obtained in the laboratory test under the condition that the raw ore contains Li₂O 1.50%.The spodumene concentrate with a Li₂O grade of 5.62%and a recovery of 74.28%is obtained in the industrial test.Compared with the original"desliming flotation"process,the recovery rate of spodumene is increased by 9percentage points,realizing the good recovery of refractory spodumene.