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Shortage of raw materials, energy shortages, environmental pollution is a major problem facing mankind, of waste for recycling is to solve the above problems important part. With mature production technology in recent years, profits have become average comprehensive recycling of waste is also growing importance for the people. Linear cutting waste slurry Si-rich and silicon carbide, and silicon and silicon carbide are important industrial raw materials. For a long time, most of the waste have been piled up and buried mortar disposal, so that not only waste resources and pollute the environment. In recent years, with the mortar line cutting waste recycling technology, wire cutting waste mortar silicon carbide and cutting fluid can already be an initial recovery (not ripe), but for the recovery of scrap silicon mortar, still in the exploratory stage (rarely reported). However, high purity silica, low density, high specific surface area, good dispersion characteristics, with its superior stability, reinforcing, thickening and thixotropy and widely used in rubber, paints, lacquers and adhesive agent industry. Therefore, this thesis mortar silicon linear cutting waste recycling study proposed the use of waste mortar while white carbon black silicon carbide recycling idea. Main contents are as follows: First, line cutting waste mortar silicon and ammonium fluoride as raw materials, through the recycling of ammonium fluoride preparation of silica (new fluorination). The thermodynamic analysis shows, 25 ℃ lower ammonium fluoride and elemental silicon reaction (△ GmΘ = -338.9 (kJ / mol)) and the excess ammonia and ammonium fluorosilicate reaction (△ GmΘ = -37.542 (kJ / mol)) The molar Gibbs function △ Gm (?) are less than zero, therefore, from the thermodynamic point of view is feasible. Then, the effects of various factors during the reaction were studied. The results show that the fluorination process conditions: the concentration of ammonium fluoride w (NH4F) is 40% to 55%, reaction temperature is 50 ℃ ~ 60 ℃ amount of ammonium fluoride and 1.1 to 1.3 times the theoretical amount of reaction Jia; amination reaction conditions: PH value in silica nucleation stage less than or equal 6.9, the growth stage of silica less than or equal 7.1; ammonium fluorosilicate concentration w (H2SiF6) controlled at 8-12 percent, two secondary sedimentation and filtration twice; early in the precipitation, ammonia drop speed was 2 drops per second (2d / s), in the sedimentation stage, ammonia drop speed was 0.5 drops per second (0.5-1d / s); Reaction temperature is 40 ℃ ~ 50 ℃; ammonia concentration w (NH4OH) is 5% -10%, stirrer speed 500r/min-700r/min; aging time of 0.5h. Secondly, through the closed loop experiments ammonium fluoride, ammonium fluoride cycle recovery of up to 95%. Finally, the obtained silica product quality were tested, the test results show that the obtained silica reached the national standard. Secondly, the study of a new method of fluorinated ammonium hydrogen fluoride and silicon key reaction kinetics. Found through experiments, found through experiments, the reaction meet two reaction rule-r = k (C NH4HF) 2; identified 50 ℃ and 60 ℃ under the conditions of reaction rate constants: k50 = 3.47 × 10-4 mol3 · L- 1 · s-1 and k60 = 5.62 × 10-4 mol3 · L-1 · s-1, and the reaction activation energy Ea = 43.16KJ/mol with the pre-exponential factor A = 3288.85. Again, the use of high concentrations of alkali dissolving silicon carbide generation system to recycle method white carbon black. The thermodynamic analysis shows, 25 ℃ lower sodium hydroxide and elemental silicon reaction (△ GrΘ = -490.612 (kJ / mol)) and sodium silicate and hydrochloric acid reaction (△ GrΘ = -586.596 (kJ / mol)) molar Gibbs function variable △ Gm (?) less than zero, therefore, can spontaneously. Then, the effects of various factors in the recovery process were investigated. The results show that the reaction conditions alkaline solution: NaOH concentration of 25% ~ 35%, reaction temperature is about 55 ℃; acidifying the reaction conditions: concentration of 9-12% sodium silicate, hydrochloric acid 20% to 25%, butanol as 13 drops (about 0.6ml), the reaction temperature is about 80 ℃. Finally, CTAB, n-butanol, N-β-aminoethyl-γ-aminopropyl trimethoxysilane, ZH-1108 and methyl triethoxysilane as modifier, the modified carbon blacks made white resistance, the use of infrared spectroscopy, thermal analysis, BET surface area and oil absorption value analysis, the results show that the realization of the self-made silica modified. Wherein the modification is the worst butanol, N-β-aminoethyl-γ-aminopropyl trimethoxy silane-modified better.
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