| Based on the social status of large annual output and low utilization rate of tailings,vanadium titanium magnetite tailings are taken as the main research object in this subject,so as to achieve the purpose of improving the use of vanadium titanium magnetite tailings with high added value.Firstly,the mechanical activation of vanadium titanium magnetite tailings was used to study the grinding characteristics and activity of vanadium titanium magnetite tailings.Secondly,on the basis of activation study,the preparation of vanadium titanium magnetite tailings composite cementitious materials and the properties of vanadium titanium magnetite tailings composite cementitious materials were studied.Then,the hydration hardening mechanism of vanadium titanium magnetite tailings composite cementitious materials was revealed by means of X-ray diffraction（XRD）,scanning electron microscope（SEM）,flourier transform-infrared spectroscopy（FT-IR）,and thermogravimetric（TGA）and isothermal calorimeter.Finally,based on the soundproof principle,the soundproof board conforming to calcium silicate plate was prepared by using the composite cementitious material and coarse vanadium titanium magnetic tailings.The main conclusions are as follows:Through the study on the characteristics and activities of vanadium titanium magnetite tailings,it can be known that the main mineral composition of tailings is augite,ferropargasite,chlorite,mica,etc.,which belongs to volcanic materials.Vanadium titanium magnetite tailings have higher grinding performance than high-silicon iron tailings.The specific surface area of vanadium titanium magnetite tailings can reach 400 m2/kg after grinding for 30min,while that of high-silicon iron ore tailings takes 100 min.By simulating the relationship between specific surface area and grinding time,the kinetic equation of grinding was obtained as follows:S=-416.81+567.69lgt,R2=0.982.The ICP-MS test of Si-Al ion concentration in vanadium titanium magnetite tailings showed that the Si-Al ion concentration in the solution increased with the extension of grinding time,and the highest Si-Al ion concentration reached 13.04 mg/L and 4.59 mg/L,respectively.The activity index of vanadium titanium magnetite tailings ranged from 62.5%70.1%,which proved the activity of vanadium titanium magnetite tailings activated by mechanical force.The hydration reaction mechanism of cement,tailing-cement composite cementitious material（3:7）and tailing-silica fume-cement composite material（2:1:7）was studied,which indicated that AFt,C-S-H gel and Ca（OH）2 were produced in the early stage of hydration products of cementitious material.With the growth of age,the amount of Ca（OH）2 in the composite cementing material system of vanadium titanium magnetite tailings decreases gradually,indicating that the degree of secondary hydration is gradually deepened.The active component in vanadium titanium magnetite tailings reacts with Ca（OH）2 to form a series of hydration products.However,the active component in tailings is far less than that in silica fume,and the amount of secondary hydration products is also small.The main hydration products include C-S-H gel,calcium aluminate hydrate（C3AH6）,AFt,etc.The flexural strength of the single-layer soundproof board and the multilayer sound insulation plate prepared by composite cementitious material and coarse particle vanadium titanium magnetite tailings conforms to the R1R2 requirements of JC/T564.1-2018 Fiber-reinforced calcium silicate plate;part I:asbestos-free fiber-calcium silicate plate.The volume and dimension content of single-doped fine steel fiber in the single-layer sound insulation plate is 0.93%,and the folding strength reaches 8.0 MPa.When only 1%of rubber powder is added,the flexural strength reaches 8.8 MPa.When the fine steel fiber and rubber powder are mixed,the corresponding content is 1.6%and3%,respectively,and the flexural strength reaches the highest,which is 6.1 MPa.The maximum flexural strength of the multilayer structural plates prepared with slurry of different ingredients was 8.2 MPa. |
