Research On Crystal Surface Hybrid Features Of Phosphorus Gypsum With Chemical Doping And Kaolinite Under Microwave Thermal Activation According To Simulation Technology

The environment was adversely affected by the large accumulation phosphogypsum and coal gangue. And due to the defect of gypsum crystals and kaolinite crystal which exist in phosphogypsum and coal gangue, the use of coal gangue phosphogypsum and solid waste have yet to be developed. In this article, with a view to provide a theoretical basis for solid waste resource utilization of phosphogypsum and coal gangue, phosphogypsum and coal gangue were simulated based on molecular dynamics and density functional theory.In order to investigate the media role in the process of gypsum rotating crystal, and in order to explore the application of computer simulation in the research process, both the crystalline type of gypsum crystal and the attachment energy of its main crystal planes have been calculated based on attachment energy(AE) model. Meanwhile, the chemical reactions between three kinds of habit modifiers including citric acid, edetic acid, and phenylglycin and gypsum crystal (12-1) and (011) surfaces have also been simulated, from which we not only get the adsorption energy between habit modifier and gypsum crystal surface, but also obtain the optimum combination of habit modifiers which is consistent with the experimental results. Furthermore, the gypsum crystal shape has been analyzed based on Scanning Electron Microscope. Additionally, the flexural strength and compressive strength of phosphogypsum are measured experimentally under the effect of different habit modifiers. The maximum values of flexural strength and compressive strength of phosphogypsum, which is mixed with habit modifier, are 3.64MPa and 7.35MPa, respectively.Geometric and electronic structure of CaSO4 (010) surfaces were calculated by density functional theory. And the adsorption energy of citric acid on the surfaces were calculated. With the assumption of the most possible adsorption position, it is found that the model that H in carboxyl of citric acid is perpendicular to Ca on the crystal surface is energetically favorable. The analysis on the adsorption mechanism reveals that the electronic transfer mainly occurs between 3d of Ca and ls of H in carboxyl of formic acid, and hybrid orbital is generated.Geometric and electronic structure of CaSO4(100),(010),(110) surfaces were calculated by density functional theory. And the adsorption energy of formic acid on the surfaces were calculated. It is found that the energy of (010) crystal surface is the lowest, and has the biggest adsorption energy, and taking place chemical adsorption. With the assumption of the most possible adsorption position, it is found that the model that O in C=O of formic acid is perpendicular to Ca on the crystal surface is energetically favorable and the adsorption is chemical. The analysis on the adsorption mechanism reveals that the electronic transfer mainly occurs between 3d of Ca and 2p of O in C=O of formic acid, and hybrid orbital is generated.Molecular dynamics was used to simulate the dehydration process of kaolinte, and density function theory was utilized to analyze the dehydration mechanism. It had been showed in the results that significant changes of kaolinite were not found at 300-600K, and in contradistinction to gradually increasing trend of coordination number of H atom, coordination number of Al atom was shown to decrease gradually after 700K, and it was showed in kaolinite XRD that the relative content of alumina increased gradually, which indicated that the dehydration of kaonilite happened in process. The analysis on the dehydration mechanism revealed that the electronic transfer mainly occurs between 3p of Al and 2p of O in hydroxyl which is connected to the Al atom, and hybrid orbital was generated between 2p of O in the activated hydroxyl and Is of H in the adjacent hydroxyl.