| Mica,as a kind of rock-forming mineral,widely exists in tailings of various metal and non-metal ores.In addition to the excellent characteristics of mica itself,fine-grained mica also has many advantages,such as good barrier,strong coverage,high adhesion and so on.If the fine-grained mica resources in tailings can be effectively recovered,not only the manufacturing cost of mica powder can be reduced,the comprehensive utilization rate of tailings can be improved,but also a kind of protection for the rare flake mica resources in China.At present,most of the fine-grained mica resources in tailings have not been effectively recovered,and there are a lot of problems in the flotation process of cationic collector commonly used,such as low solubility,difficult defoaming,environmental pollution and so on.Under the premise of environmental protection,the mixed collector can greatly improve the flotation recovery of mica,realize the resource utilization of tailings and save the cost of tailings treatment.Therefore,it is not only of great practical application value to carry out the research on floatation technology of fine-grained mica with mixed collector,but also has a guiding role in the selection and proportion of mixed collectors.Based on muscovite as the research object,the cationic collector was mixed with different anionic collector and nonionic collector respectively in this paper.It focuses on the self-assembly process of the mixed collector at the gas/liquid interface and the adsorption process at the solid/liquid interface as the research direction to carry out the synergistic mechanism of different mixed collectors in the flotation.The synergistic mechanism was studied by means of flotation test,surface tension,contact angle,zeta-potential and molecular dynamics simulation method.The main work and conclusions including:The pure mineral experiments showed that the addition of anionic collector or nonionic collector to dodecylamine could improve the ability of dodecylamine to collect muscovite.For different of anionic/cationic collectors,they could produce synergistic effect in the range of pH=5～13,and flotation recovery of muscovite was significantly increased than that of cationic collector used alone.Under the same collector dosage,the optimum molar ratio of dodecylamine to different anionic collectors was not the same,and the trend of muscovite flotation recovery changing was not consistent with collector molar ratio;Adding nonionic collector to dodecylamine could improve the ability of dodecylamine to collect muscovite,and obviously reduce the sensitivity of dodecylamine to pH in the flotation of muscovite.With the increase of carbon chain length of nonionic collector,the performance of cation/nonionic collector increases gradually.The self-assembly process of mixed collector system was simulated by PCFF force field.Based on the analysis of gas/liquid interface configuration,component concentration and interaction energy,the surface activity of different mixed collector was investigated.The simulation results show that dodecylamine was more vertical in the gas/liquid interface under the action of anionic collector than used alone,the concentration of counter ions around the amino group was reduced,the hydration of amino group was increased.The anionic/cationic collector showed high surface activity.However,for different kinds of anionic collectors,the ability to improve the surface activity of dodecylamine was not the same,and the surface activity of anionic/cationic collector was also different under different molar ratio conditions.In the self-assembly system of cationic/nonionic collector,dodecylamine was more vertical at the gas/liquid interface than nonionic collector,and the arrangement of mixed collector showed higher compactness.With the increase of the carbon chain length of the nonionic collector,the improvement effect was gradually enhanced.Increasing the molar ratio of dodecylamine in the mixed collector was conducive to improve the compactness of mixed collector micelle,but the hydration of amino group decreased significantly.The adsorption process of the mixed collector on muscovite(001)surface was studied by PCFF-INTERFACE force field and the adsorption configuration,atomic density distribution,radial distribution function,mean square displacement and adsorption energy were investigated.The simulation results show that in the adsorption process of anionic/cationic on muscovite(001)surface,dodecylamine ions were first adsorbed on the muscovite surface,and then,the anionic collectors were indirectly inserted into the adsorption layer of dodecylamine ions through electrostatic force,hydrogen bond and hydrophobic association,forming indirect adsorption with muscovite surface.Although the adsorption process was similar,the mechanism of increasing the hydrophobicity of muscovite surface by different anionic/cationic collectors was not the same,which was closely related to the adsorption energy and carbon atom density.Under the condition of different collector molar ratio,the adsorption state of anionic/cationic collector on muscovite(001)surface was quite different.When the molar ratio of dodecylamine to sodium dodecyl sulfonate was 1:1,the hydrophobicity of muscovite(001)surface was the best,but the adsorption capacity of dodecylamine on muscovite surface was not saturated,and the adsorption energy was the lowest.Therefore,it could be concluded that the optimum molar ratio condition of anionic/cationic collector for muscovite flotation was to increase the adsorption capacity of cationic collector on the muscovite surface on the premise of ensuring the best stability of the anionic/cationic collector adsorbed on the surface of muscovite.At this time,the ratio of the number of anionic and cationic collectors was the best molar ratio.In the adsorption process of cationic/nonionic collector on the muscovite(001)surface,dodecylamine ions was first adsorbed on the muscovite(001)surface,while the nonionic collector was mainly indirectly adsorbed on the muscovite(001)surface through the hydrophobic association between carbon chains,thus forming a stable adsorption structure.With the increase of the carbon chain length of nonionic collector,the hydrophobicity of muscovite surface increases gradually.Under the condition of different collector molar ratio,the adsorption state of cationic/nonionic collector on muscovite(001)surface was obviously different.When the molar ratio of dodecylamine to octanol was 2:1,the hydrophobicity of muscovite(001)surface was the best,the adsorption capacity of dodecylamine on muscovite surface was saturated,and the octanol adsorbed by semimicelle was the largest.Therefore,it could be concluded that the optimal molar ratio condition of cationic/nonionic collector for muscovite flotation was to increase the number of nonionic collectors with semimicelle adsorption under the condition that the cationic collector adsorbed on muscovite surface was saturated.At this time,the ratio of the number of cationic and nonionic collectors was the best molar ratio.The flotation results of actual molybdenum tailings show that under the action of dodecylamine/sodium dodecyl sulfonate,the concentrate K2O grade of muscovite increased from 2.04%to 9.22%and the recovery was 70.64%after one roughing,three cleaning and one scavenging;while under the action of dodecylamine/dodecanol,the concentrate K2O grade of muscovite was 8.99%and the recovery was 73.20%.Both of them were higher than the flotation performance which used dodecylamine alone,and the collector dosage was also reduced.The results verify the conclusion of molecular dynamics simulation that the best type and the best molar ratio of the mixed collectorsThere are 154 figures,44 tables and 141 references in this paper. |
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