Low Modulus Sodium Silicate Preparation Process Of Silica And The Study Of The Internal Structure Of Silica

Coal gangue is solid waste generated in coal mining,occupation of land and pollute environment.The comprehensive utilization of gangue is a resource and environmental problem that needs to be solved in China’s sustainable development strategy.The research group has obtained a feasible method for the comprehensive utilization of coal gangue in the preliminary study,and the products such as iron,aluminum,titanium and calcium are made,and the water glass with a modulus of about 1 is obtained.For low modulus water glass,most of it is used as hardening agent to reinforce the soil,and the comprehensive utilization value is not high.In this study,Based on the low modulus sodium silicate as raw material,using method of sulfuric acid and the preparation of silica carbide,The preparation method and the product performance were compared,and the carbonization method was obtained.Because of the quality of white carbon black products prepared by carbonization method is quite different.And the carbonation condition affects the internal structure of the product,then the internal structure influences the evaluation index of the product.In this paper for the three response factors:reaction temperature,concentration of sodium silicate and the amount of electrolyte Na₂CO₃,under the microstructure analysis of white carbon black production,the conclusions are as follows:（1）According to the result of orthogonal test,for low modulus water glass sulfuric acid method preparation of white carbon black,the optimum reaction conditions:reaction temperature is 70℃,V（sodium silicate）:V（water）is1:2（sodium silicate concentration is 8.19%）,the rate of drop of sulphuric acid is 2.5mL/min,Added sulfuric acid concentration is 30%,without electrolyte Na₂SO₄,made of white carbon black oil absorption value of 2.30 mL/g,specific surface area of243.262 m²/g,oil absorption value reach industry standards,specific surface area reach the standard industry class A.（2）According to the results of the orthogonal test,for low modulus water glass sulfuric carbonation method preparation of white carbon black,the optimum reaction conditions:reaction temperature is 50℃,V（sodium silicate）:V（Na₂CO₃ solution）is1:1（the sodium silicate concentration is 11.86%）,the electrolyte concentration of Na₂CO₃ is 5%,40%CO₂ mixed gas flow is 150 mL/min.At this time the white carbon black oil absorption value is 2.60 mL/g,the specific surface area is 284.739 m²/g,oil absorption value reach the industry standards,specific surface area reach the standard industry class A.（3）The oil absorption value and specific surface area of the white carbon black carbon prepared by carbonization method are slightly higher than that of sulphuric acid method,and the carbonization method use Lime-kiln gas,reducing the greenhouse gas emission while reducing the use of inorganic acid.Therefore,using low modulus water glass prepare for white carbon black,the carbonization method is better than sulfuric acid method.（4）Because the dibutyl phthalate（DBP）,which is needed for the determination of oil absorption value,does not penetrate into the pores of white carbon black,the particle size of white carbon black is negatively correlated with the oil absorption value.The specific surface area of silica was positively correlated with pore volume and surface hydroxyl content.In order to prepare white carbon black with larger surface area,it can be used to increase the pore volume and increase the surface hydroxyl content.The pore structure and pore diameter of white carbon black products prepared under different conditions are not very different.Therefore,in order to prepare the white carbon black products with larger surface area,it is necessary to increase the number of pore channels.（5）The proper concentration of water glass and the addition of electrolytes can produce better white carbon black products.When the concentration of water glass or electrolyte is too high or too low,the particles of white carbon black is larger,and the particles are relatively tight,which leads to a reduction the oil absorption value and the specific surface area of the white carbon black.