Study On The Structure-property And Mechanism Of New Type Of Quaternary Phosphonium/Ammonium Salts And Their Application

Silicate minerals are the main gangue minierals of iron and bauxite ores. However, the surface chemical properties of silicate minerals are similar with that of valuable minerals and silicate minerals slime in flotation process, which make mineral flotation separation difficult and SiO2of the concentrate is too high so as to influence subsequent smelting process. Thus utilization of oxidized ores resource has been restricted. The relationship between reagent structure and flotation performance, the influence of minerals surface properties differences to reagent absorption and the microcosmic differences of different reagents adsorption have been detailedly and systematically studied in this thesis by using various modern analysis technologies in combination with theoretical investigation and experimental study. A class of novel quaternary phosphonium salt cationic surfactants and stellate quaternary ammonium salts were used as revers flotation collectors for the de-silication of oxidized ores, based on the invesgations of structure-activity relationship between the amine cationic collectors and their collecting ability. The results in this work have an important theory meaning and an actual application value. Main conclusions and innovations of this thesis are listed as follows:(1)The investigations of quantitative structure-activity relationship of Quaternary Ammonium SaltThe aim of this research is to explore the relationship between the quaternary ammonium salt structural and selectivity by QSAR. Based on the selection and calculation of reagents quantization parameters, topological parameters and selectivity indexes, QSAR model with robust predictive abilities were obtained. It can be concluded, by means of the model, the shape of molecule, total energy and hydrophobic property are the three major factors affecting the selectivity of collectors; and the reagent possessing appropriate log P values and more negative total energy is the best collector for the flotation separation of aluminum-silicate minerals.(2) Molecular design of reagent in accordance with the differences of the mineral surface propertiesBase on desity functional calculations, molecular dynamics simulation and the atom in molecular theory, the effect of diaspore and kaolinte surface atoms for reagent adsorption has been discussed and the relationship between different surface properties and drug adsorption behavior has been established, providing a basis for the option of group configuration for new reagent.The electronic bands near Fermi level of diaspore and kaolinite are provided mainly by O atoms, the only electronegative atom in the mineral surface, which indicates that O atoms are the reactive sites in diaspore and in kaolinite. The atoms of outer layer for kaolinite and diaspore are O atoms and H atoms respectively, which is the main reason why adsorption behavior of reagents is different on two mineral surfaces. The selectivity of collector for aluminosilicate minerals can be improved effectively by using the space steric effect which can hinder the approach of reagents molecule and O atoms of diaspore and increase the bonding of reagents and kaolinite O atoms.The mechanisms of cationic collectors adsorbed on kaolinite and the relationship between the surfactants structures and their flotation ability are discussed. It is showed that flotation of kaolinite using cationic collector is mainly attributed to the physical electrostatic effect. Changing N atoms into P atom as central atom of collector can change the charge character of its cationic group, can enlarge the electrostatic effect, and thus can improve the collecting ability for the negative charged minerals.(3)Adsorptive characteristic research of collector on silicon containing mineral surfaceThe differences of surface electrical potential, adsorption density, adsorptive micro-polartity and aggregation number are investigated through Zeta potential tests, adsorption measurements, spectrofluorimetry and AFM detection. Under the common action of electrostatic attraction and hydrophobic association of hydrocarbon chain, several main adsorptive processes of cationic collector which include the free adsorption, semi micelle adsorption and micelle adsorption. The reagent structure is related to the charged distribution and the space steric effect which can affect the reagent adsorption and aggregation on mineral surfaces, revealing the internal relationship between collector structure and mineral flotation.AFM observations show that the adsorption morphology of different reagents on mineral surface is different. The morphology of the same agent also changes and successively appeared monolayer, bilayer and the multilayer adsorption with the increase of reagent concentration.(4)The reverse flotation desilication of natural oreThe Henan bauxite with Al/Si5.36was used as raw material for flotation tests. The flotation ability of1231and novel collectors is compared in the same condition. The results show better flotation results with Al2O3of67.84%and the Al to Si mass ratio of9.18can be obtained by using novel collectors. This flotation results totally fulfill the requirements of bauxite Bayer processing. The novel collector is also superior to the corresponding conventional quaternary ammonium salt in iron ore flotation. Due to the optimization of flotation separation process, the iron concentrate with TFe of62.19%, recovery of80.19%was obtained. This is in good agreement with the previous theoretical research.