Preparation Of Silica Aerogel Thermal Insulation Material From Iron Tailings

Iron tailings is a kind of solid waste after the concentrate is selected by the concentrator.According to incomplete statistics,there are 5 billion tons of tailings in China,and more than500 million tons of tailings are discharged annually.In the process of stockpiling,iron tailings not only occupy a large amount of land resources,but also cause a serious impact on the local ecological environment.Meanwhile,with the increase of tailings stock,it also poses a serious threat to the safety of downstream residents.The research and comprehensive utilization of iron tailings is of great significance to the sustainable development of national resources.In this paper,sodium silicate solution was prepared by alkali leaching from iron tailings,and hydrophobic silica aerogels and composites were prepared by sodium silicate solution.Silica aerogel is a kind of special porous material with excellent properties such as low density,high porosity,high surface area and low thermal conductivity.In recent years,with the development of different types of aerogel synthesis technology,the porous material has been widely discussed in many fields,especially in the field of thermal insulation.Iron tailings as raw material,discussed the influence of different process parameters on the Si extraction yield,eventually find:screening when sodium hydroxide with iron tailings of mass ratio of 1.0:1.5,calcination temperature is 550 ~oC,leaching of solid-liquid ratio of 1.0:5.0,leaching temperature is 80 ~oC,time of 4 hours,combined with the actual demand of industrial production,finally can obtain the highest Si extraction yield of 50.7%.The influence of different factors on the final silica aerogel product was discussed with sodium silicate solution extracted from iron tailings as the silicon source,and the properties of the sample density,thermal conductivity and pure water contact angle were tested.Results show that when the material liquid dilution twice(0.100 mol/L sodium silicate solution),using hydrochloric acid as acid catalyst(2.000 mol/L)after add slowly drops makes the silicon solution to form gel,step-by-step adding deionized water immersion to remove the pore inorganic salt ions,and then using anhydrous ethanol as solvent exchange for replacement of the water in the channel,then using trimethylchlorosilane(TMCS)as hydrophobic modifying agent to hydrophobic modification of wet gel,the last set temperature program(60 ~oC for 1 hour 90 ~oC for 2 hours 120 ~oC for 1 hour)in ambient pressure.The hydrophobic silica aerogel prepared under this condition has low density(0.15 g/cm~3),low thermal conductivity(0.016w/m·K)and superhydrophobic(water contact Angle is 150°).Silica aerogel composite glass fiber composite materials prepared under the same conditions also have the characteristics of low thermal conductivity(0.016 w/m·K)and superhydrophobic.This paper takes iron tailings as the starting point,extracts the silicon element to carry on the high value-added utilization,takes the industrial production factor into full consideration,provides the reference for the utilization of iron tailings and the application of hydrophobic silica aerogel.