subject: High Purity Nanosio2 Powder Is Produced From Waste Silica Fume [print this page] Silica fume is a fine silica powder material generated in the smelting of ferrosilicon alloy and industrial silicon. The process produces the SiO2 and Si gas. And they have rapid oxidation and condensation precipitation with oxygen in the air. The main impurities are Fe2O3, Al2O3, MgO and CaO, NaO, other metal oxides and amorphous carbon. The silica fume production is huge. 3 tons of industrial silicon can get an average production of l tons of silicon powders. 1 tons of silica fumes can also be got from 5T ferrosilicon.
In a long time, silica fume has been used as concrete and refractory additives. Countries around the world are related to standard silica fume concrete and refractory additives. In China, high performance concrete with mineral admixtures national standards to ensure that the provisions of silica fume for concrete and refractory additives minimum SiO2 content should be greater than 85%. At present, a low-grade silica fume (SiO2> 85%) by burning, acid leaching and other processes to remove amorphous carbon and acid soluble oxides in order to improve the micro-silica fume grade, or by the silica fume with lime calcining After the acid dip preparation of silica products meet national standards in order to improve their economic value.
However, the low content of silica fume due to low market prices, the high cost of purification, mostly discarded as industrial waste, not only resulted in wastage of resources, also caused serious environmental dust pollution. Low content of silica fume (SiO2
