Study On The Quantitative Structure-activity Relationship And Oriented Synthesis Of Novel Quaternary Ammonium Cationic Collectors For Removal Of Silicates

As our country’s steel output increasing, the supply of our country’s ironresource is still not adequate to the demand, which results in the foreign dependenceis above65%in2012~2013. Our country’s iron reserve is abundant, but most ofthem are refractory ores, the disseminated size is quite fine, containing a largeamount of iron-bearing silicate minerals. If only using magnetic separation, does thequartz easily be mingled with iron concentrate, which will result in the quality ofiron concentrate deteriorating. It needs to do the cationic reverse flotation on the ironconcentration from magnetic separation. However, traditional cationic collectorshave drawbacks as follow: low separation efficiency, the foam is not easily brokenand even affecting the normal production, nondegradation.In order to resolve the above problems, this research is supported by theNational863Program “The degradability and environmental safety evaluation oftypical flotation reagents”(No.2007AA06Z123), which aimed at to exploring a kindof high efficient and environmental friendly cationic collectors.1. Based on the elementary structure of cationic collectors, a series of novelquaternary ammonium salts, like mono-ester quaternary ammonium salt (M301),diester bis-quaternary ammonium salts (M302、M303)，the modified dodecylaminequaternary ammonium salt (M331), dissymmetric bis-quaternary ammonium salt(M332), symmetric bis-quaternary ammonium salt (M333). By using Gaussian09quantum chemistry program to optimize the molecular structure of these novelquaternary ammonium cationic collectors, their molecular parameters like bondlength, bond angle and dihedral angle were obtained, which prove that the design ofnovel cationic collectors’ molecular structure is feasible and reasonable.2. The novel quaternary ammonium cationic collectors were synthesized byquaterisation reaction, esterfication reaction. The sodium tetraphenylboratetitrimetric analysis for products’ purity was used to determing the optimum reactioncondition. The results of nuclear magnetic resonance and FTIR proved that theproducts are target products. 3. In the pure minerals flotation of quartz and magnetite, novel collectorsM332and M303can obtained high floating rate gap between quartz and magnetite,which is above90%, however, which of dodecylamine is only73.29%. It indicatedthat M303and M332have much better selectivity than dodecylamine. Throughmanually mixture minerals separation tests, the classification of efficiency of M303、M331and M332is proved that their efficiency of classification are74.23%,76.89%,75.97%, respectively, which are much higher than dodecylamine (71.99%).4. By using the CASTEP module in quantum chemistry program MaterialStudio6.0, the crystal plane properties of quartz and magnetite were studied. Theirband structure, total/partial density of states and the population of atom insubstitutional doping were also obtained, which revealed the active site on quartzand magnetite. Zeta Potential test showed that the isoelectric point (IEP) of quartz is<3and the IEP of magnetite is6.26, which indicated that novel quaternaryammonium cationic collectors preferentially adsorbed on the surface of quartz byphysical adsorption. By using FTIR test to reveal that the adsorption of novelcationic collectors on quartz is hydrogen-bond interaction and bonding interaction,while the adsorption of novel cationic collectors on magnetite is reversible physicaladsorption.5. By using Gaussian09software and the DMol3module in Material Studio6.0, to do the quantum chemistry calculation on novel cationic collectors and quartz.The diagram of relationship between flotation results and quantum parametersindicated that the frontier orbital energy gap can do a better analysis on collectors’selectivity, and the linear fitting equation of frontier orbital energy gap andclassification of efficiency of flotation is y=-0.0199x+1.5896; The moment ofdipole can do a better analysis on collectors’ collectability, and the linear fittingequation of moment of dipole and floating rate is y=1.2625x-65.853. The flotationproperties can be deduced by using these equations to do calcultation after abstainedthe novel collectors’ quantum chemistry parameters.6. The grade of concentrate after magnetizing roast–magnetic separation onJiugang iron ore is around54%, after reverse flotation by using novel cationiccollectors, the grade of concentrate can be increased to above61%, and the grade ofsilicon can be increased by6%, besides, the novel collectors can their low-temperature resistant, foam fragility and biodegradability. Exploring A kind ofdissymmetric quaternary ammonium salts with ester group, bis-polar group is thedevelopment direction for designing high efficient and environmental friendlycationic collectors...