The Study On The Penetration Property Of Red Mud Filtrate And Transport Process Of Contaminant

The migration processes of pollutants such as soluble contaminants and suspended particles have become an important research topic in environmental and geotechnical engineering. These researches have an important academic significance and application value in the field of ocean tunnelling engineering, pollutant treatment, chemical industry, oil exploration, nuclear waste disposal, grouting engineering in civil engineering and soil remediation, which is also the research task of this thesis. This thesis is to study the penetration properties of red mud and its pollution and corrosion in porous medium as the geotechnical engineering background. The chemical compositions of several typical red mud filtration are studied by laboratory tests, and the penetration characteristics and the problems of migration process in porous medium is analyzed. Then the migration process of contaminant in porous medium is analyzed by analytical method. The main research conclusions include:(1) The chemical compositions of two kinds of red mud filtrate samples, a gray sample from the Jiaokou of Shanxi project and a reddish brown sample from Shandong project, are analyzed, including the alkaline ion such as OH" and acidic ion such as SO42-and NO3-in the concentrations. These discussions provide the basis for the research of migration process of contaminant and corrosion resistance,(2) According to soil column penetration experiment of red mud,3different concentrations and3different flow velocities are discussed, and the effects of physical factors on the migration characteristics of red mud in saturated porous medium are studied, which include the transports of suspended particles and OH-1ion. The seepage and neutral filtrate penetration process are also studied, which is compared with the filtrate penetration process of red mud particles with strong alkaline. The influences of chemical factors on the migration characteristics of suspended particles of red mud filtrate in saturated porous medium are also analyzed. The difference of standard curves between concentration and turbidity of the red mud for the two cases with and without OH-1ion are compared; and furthermore the effect of OH-1ion on migration processes are investigated.(3) According to soil column penetration experiment of natural silica powder,3different concentrations and3different flow velocities are studied. This natural silica powder is composed of two different particles of10μm and47μm (mass50%each). In order to analyze the effect of OH-1ion on the migration process of silica powder, the difference of standard curves between concentration and turbidity of the silica powder for the two cases with and without OH-1ion are compared. Moreover, the physical inherit of OH-1ion on migration processes of red mud are discussed.(4) A mathematical model is developed to describe the seepage transport of particles in porous medium, which takes into account the diffusion effect in the process of deposition kinetics. Then, the general solution with an item of the particle source is obtained by Laplace transform and inverse Laplace transform. Based on the elementary solution of an instantaneous plane source, the semi-analytical solution of the particle transport equation is derived in a semi-infinite saturated porous media containing a particle source whose concentration varies with time and space. In the calculation example, many cases are discussed including the release source with decreasing exponentially, cyclic variation, and short-term release effect, etc.(5) The governing equations of contaminant transport in saturated porous medium with the release effect of absorbed solutes were established to account for the one-dimensional flow and three-dimensional dispersive effect. The elementary solution for the case of point contaminant source instantaneously applied on the surface of porous medium was derived by using the Laplace transform and Fourier transform and their transform inversions. Then, analytical expression for contaminant concentration in porous medium subjected to a local contaminant source with arbitrary geometry and varied intensity with time and coordinates on its free surface are developed by integration method. The migration processes of some typical cases are discussed including the cases of circular domain source with constant concentration of pollution, the pollution source with exponential decay and the pollution source with cyclic fluctuation, etc.