Preparation Of Silica From Precipitation Of Metal Residue By Furnace Smelting And Its Modification

Electric furnace smelting metal slag(smelting slag), which contains low valuable metal and doesn’t have the value of recycling, is a kind of solid waste produced in the process of smelting nonferrous metal in electric furnace. The treatment and disposal of smelting slag are mainly stacking and landfill, which take up a lot of space and cause the potential environment harm. 50% component of silicon in smelting slag is suitable for the preparation of silica, which has a wide range of application. The recovery and reuse of smelting slag can create better economic benefits, and also can reduce the required accumulation space. The experiment, used smelting slag as raw material and had three processes of removing the Fe element in smelting slag by hydrochloric acid leaching, preparing silica used acid-leaching slag and modifying silica. This paper researched the effects of conditions in the process on silica product and formed optimized process of modified silica using smelting slag, which have good application value.In the process of acid leaching, the paper studied the effects of the solid-liquid ratio, addition amount of HCl, acid-leaching temperature and stirring speed on the removal rate of Fe in slag. The results showed that, when the solid to liquid ratio was 1:25(g/m L), the addition amount of HCl(50%) was 90 m L, the acid-leaching temperature was 40℃, the stirring speed was 300 r/min, the removal rate of the iron in slag was up to 81.25%.This experiment researched the effects of Na OH concentration, reaction time, solid-liquid ratio, stirring speed, and reaction temperature in the preparation of precipitated silica.And the experimental study showed that the optimum process conditions were: the concentration of Na OH was 8 mol/L, the reaction time was 6 h, the solid-liquid ratio was 1:10, the stirring speed was 300 rad/min, the reaction temperature was 90℃. The obtained silica products under these conditions, its content of Si O2 reaches 92.84%, DBP value reaches 2.95, bulk density is 0.27, heating reduction is 5%, ignition loss is 6.8%, which consistent with the HG/T 3061-2009 silica product requirements. By infrared spectroscopy, X ray diffraction, scanning electron microscopy, transmission electron microscopy and particle size analyzer, the product is determined as amorphous amorphous hydrated silica, which gathers by approximate spherical and its particle size are mainly distributed in the 10.1~147.7 nm, which accounts for 56.1% of the total.In addition, this paper chose PEG 2000, n-butanol and n-octanol as modifier to add directly in the process of preparation of precipitated silica. The results showed that, the optimum process conditions were: the addition amount of PEG 2000, n-butanol and n-octanol respectively was 4% of the volume of sodium silicate, 4% of the volume of sodium silicate and 16% of mixed volume. Under the conditions, the morphology and dispersion of silica particles can be effectively improved and the particle morphology of silica is spherical.