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High purity nanoSiO2 powder is produced from waste silica fume

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 <70%) and nickel powder as raw materials by acid leaching, hydrofluoric acid dissolution, hydrolysis, washing drying, burning and other processes, preparation of SiO2 content is greater than 97% of the nano-SiO powder. Prepared powders have high purity, small particle size and large surface area, can be widely used as additives to rubber, paint, ceramics, paint, ink and other fields, not only make full use of silica fume resources, while improving the micro-silicon the value and economic value of the powder, has broad application prospects.

Take a certain amount of silica fume, adding 20% hydrochloric acid, placed in constant temperature water bath heated to 80 ° C stirred for 2h, centrifugal separation, precipitation repeated washing with distilled water to the washing liquid is colorless, add the appropriate amount of hydrofluoric acid dissolved filtered supernatant, under vigorous stirring was added dropwise to the PEG600 ammonia solution in the 60 ° C, dropping after the isothermal reaction. Centrifugation, the supernatant after drying available to the NH. Lower precipitate washed with ethanol several times, placed inside the oven temperature 105 ° C constant temperature 10h, from white powder moved into the crucible, placed in a muffle furnace at 600  for burning 2 h of natural cooling, can be prepared white nano-SiO2 powder.

Metal powder supplier uses waste silica fume as raw materials, by acid leaching, HF acid dissolution, hydrolysis, washing drying, burning and other steps, nano-SiO2 powder can be papered. SiO2 content is greater than 97% with an average particle size of 90 nm and specific surface area of 210m 2/g. The powder has the advantages of high SiO2 content, uniform particle size, large surface area, etc., it can be used as high quality additives in the field of rubber, paintPsychology Articles, ceramics and pigments. It has broad application prospects.Source:

Article Tags: Silica Fume, Refractory Additives

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