Study On The Influence Of Nanobubbles On The Flotation Behavior Of Rare Earth Phosphate Or

China is the largest producer,consumer and exporter of phosphate rock and phosphate in the world.Although the phosphate ore resources are abundant in china,but most phosphate ores have low grade.Strengthening the development of key technologies for mid-low grade phosphate ore is of great significance to the sustainable development of phosphate chemical industry in China.Zhijin phosphate ore in Guizhou is an ultra-large middle and low grade phosphate ore containing rare earth.The explored reserve of phosphate ore is 3.39 billion of tons,and the average grade of P₂O₅ is 17.20%.The reserve of rare earth oxide（RE₂O₃）in phosphate ore is second only to baiyunebo rare earth ore,which has great development value.Mineralogical studies show that there is a positive correlation between rare earth content and phosphorus content in the ore,and rare earth elements mainly occur in collophane in the form of isomorphism.Therefore,enrichment of rare earth in phosphate concentrate by flotation and extraction of rare earth from phosphate concentrate by wet-process phosphoric acid are the most feasible industrial comprehensive utilization scheme.Due to the fine disseminated particle size,such ores must be finely ground to achieve appropriate dissociation degree.The conventional flotation method is difficult to separate and has low efficiency.The nanobubbles（NBs）flotation technology developed in recent years can significantly enhance the flotation of fine particles and improve the flotation efficiency.In this paper,nanobubbles are generated by a nanobubbles generator,and the basic characteristics of nanobubbles are characterized by dynamic light scattering technology.And the effect of nanobubbles on reverse flotation of low-grade rare-earth containing phosphate ore in Zhijin was investigated.The specific research contents are as follows:（1）Nanobubbles were generated by nanobubble generator,and the particle size of nanobubbles was measured to be between 100 and 500 nm by dynamic light scattering technology.The particle size of nanobubbles decreases with the increase of cavitation time.When the cavitation time exceeds 6 min,the increase of cavitation time cannot reduce the particle size of nanobubbles.The nanobubbles have good stability in the solution,and can still be detected in the solution after 48 h.（2）The effect of nanobubbles on the reverse flotation of mid-low grade phosphate ore under different process parameters（grinding fineness,modifier’s type and dosage,dosage of collecter）was studied by flotation machine.The experimental results show that the use of nanobubbles has a significant effect on flotation performance.With the increase of grinding fineness,nanobubbles flotation is generally better than that of ordinary water flotation.By linear fitting,it is found that rare earth elements in flotation products are positively correlated with P₂O₅ grade and negatively correlated with Mg O content,indicating that rare earth can be effectively enriched into phosphate concentrate by nanobubble flotation.（3）The flotation kinetics test results of dolomite with different particle sizes show that the nanobubbles reduce the flotation rate of-150+75μm dolomite,and the flotation rate constant k is almost unchanged.For-75μm particle size,with the decrease of dolomite particle size,the introduction of nanobubbles improves the limit recoveryε_∞and flotation rate k.This may be the reason for the decrease of Mg O removal rate caused by nanobubbles in the acturel ore flotation test at low grinding fineness.（4）The effect of nanobubbles on the surface properties of minerals was further studied by Zeta potential analysis,laser particle size analyzer,microscope observation and contact angle test.The results show that under acidic conditions,nanobubbles increase the contact angle of dolomite surface,and have little effect on the contact angle of apatite surface.The adsorption of nanobubbles on the surface of dolomite makes the CO₂ bubbles generated by dolomite acidolysis adhere to the surface of minerals and promote the floating of dolomite.Nanobubbles can reduce the surface potential of dolomite particles and promote the agglomeration of dolomite particles.