| China has abundant mineral resources.With the development of the economy,the demand for resources is increasing.What's more,characteristics like ‘poor,miscellaneous' of the mineral resources in China is becoming more and more prominent.On the one hand,coarse particle flotation can remove part of gangue in advance,and reduce the influence of gangue on subsequent operations and improve the processing capacity.On the other hand,it can reduce grinding operations and power consumption,which has a certain positive effect on tailings management and reuse.In this paper,glass beads were used as model minerals to study the detachment behavior of coarse particle flotation,and the effects of different frother,particle size and hydrophobicity on the quasi-static detachment process between bubbles and particles,the dynamic detachment probability of gas/liquid interface and the recovery rate of coarse particle flotation were explored,which provided theoretical support for the realization of highefficiency flotation of coarse particles.The surface hydrophobicity of the glass beads with fraction size of +0.4-0.6 mm,+0.5-1.0 mm,+1.0-1.5 mm,+1.5-2.0 mm,+2.0-2.5 mm were modified by methylation reaction.The larger the particle size,the smaller the relative surface area of the particles,and the larger the hydrophobic contact angle.The test results of frother properties showed that the order of surface tension of frothert is polypropylene glycol > sec octanol > polyethylene glycol > MIBC > n-pentanol.And the relationship of viscosity is polypropylene glycol > polyethylene glycol > sec octanol > MIBC > n-pentanol.The maximum viscosity of polypropylene glycol is 347.15 mPa s.The bubble particle quasi-static detachment process was studied by using bubble particle detachment test device.The evolution of contact angle and detachment force of bubble particle quasi-static process under different forther,particle size and hydrophobic contact angle was explored.The results showed that the process of bubble particle quasi-static detachment can be divided into three stages: bubble stretching,bubble sliding and bubble necking.Meanwhile,the change of dynamic contact angle can also be divided into three obvious stages,which are in good agreement with the three stages of detachment process.Frothers have certain effects on the detachment force.When the surface tension is large,the detachment force is less affected by the surface tension.The detachment force between bubbles and particles can be increased to a certain extent by appropriately reducing the surface tension of the solution.But the stability between bubble particles was poor at low surface tension.With the increase of particle size,the detachment force between bubble particles increased,which is mainly because the larger particle size can obtain a larger contact area and a longer three-phase contact line length.The hydrophobic contact angle of particles is still an important factor to determine the detachment between particles.With the increase of hydrophobicity of particles,the detachment force increased obviously.According to the classical model,the influence factors of detachment force are surface tension,contact line length,and contact angle,which is consistent with the previous experimental conclusion.In the presence of frother,the rising state of single bubble and bubble-particle aggregate in solution was studied by the bubble-particle aggregate dynamic rising and floating observation system.And the influence of frothers,particle size fractions,and hydrophobic contact angles on the probability of particle detachment at the gas-liquid interface was further studied.The results show that the rising stability of aggregates in the solution is higher than that in the case of the single bubble.The order of bubble size is n-pentanol > MIBC > polyethylene glycol > sec octanol > polypropylene glycol.The bubble size and surface tension have a great influence on the bubble rising speed in the solution.The bubble rising speed is no agent > n-pentanol > MIBC > polyethylene glycol > sec octanol > polypropylene glycol.At the gas/liquid interface,the detachment probability of particles using sec octanol solution is the lowest,which is 9%,and that using polypropylene glycol solution is the highest,which is 20%.The addition of frother can reduce the detachment probability of particles to a certain extent,which is mainly determined by the velocity of bubbles when they reach the interface and the size of detachment force between bubbles.The detachment force between bubbles and particles is also determined by the hydrophobicity of particles themselves and the size of particles.The detachment force can significantly affect the detachment probability of bubble-particle aggregates at the gas-liquid interface The probability of detachment of coarse particles from the surface of the bubble is obviously higher than that of fine particles.Coarse particles have large inertia,and when the bubbles reach the gas-liquid interface,the sliding displacement of the particles on the surface of the bubbles becomes larger,which leads to detachment.The hydrophobicity of the particle itself has a great influence on detachment probability.With the increase of hydrophobicity,the detachment probability decreased gradually.With the hydrophobicity of particles increasing,the detachment force increased,and the stability between the bubble and particles become stronger,and the probability of particle detachment become lower.The results of the coarse particle flotation test showed that the recovery of the coarse particle increased first and then decreased with the increase of frother dosage.When the frother dosage is 300g/t,the flotation recovery is high.The two frothers,namely octanol and MIBC,obtained better flotation results than other agents,which are mainly attributed to the high foam layer thickness and long existence time.The hydrophobicity of particles itself is still the key factor to determine the results of flotation.The higher the hydrophobic contact angle of particles,the higher the recovery rate can be obtained.There are 67 pictures,6 tables and 97 references in this paper. |
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