Silica Production Baghouse
For the formation of silicon, the carbon requirements have to be precise. Excess carbon results in SiC formation. On the other hand insufficient carbon results in excessive SiO formation which is lost in the off-gas. As the raw materials are consumed, a cave is formed around the electrode, and the top of the charge bed becomes a hard crust. This crust must be physically stoked (rabled) from the top in order for additional raw materials to be fed. The energy required for the process is provided by the electric arc between the electrodes.
Operating Conditions
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Dust To be handled:
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Nature of dust: Fine, free-flowing, mildly abrasive
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Cleaning Mode: Online
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Design Gas temperature: 135/180/240 degree Celsius
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Design Surge Temperature: 150/200/260 Degree Celsius
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Dust Load:
At a 100% stoichiometric ratio, a quantity of 0.4 kg of carbon would be used for every kg of SiO2. The silicon carbide reaction produces SiC and is well known to occur when accretions of SiC are found in the cooler parts of the furnace. The excess carbon increases the amount of CO escaping from the furnace burden. That CO burns to CO2 under the hood and leads to an increase in the X-factor.
Typical X Factors :
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Si-Metal X = 1.3 to 1.5
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75% FeSi X = 1.1 to 1.3
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SiMnX = 0.9 to 1.1
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0% FeSi X = 0.8 to 1.0
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FeCr X = 0.6 to 0.8
Considering the low density and low settling velocity of the silica fume generated by FeSi and Si smelting furnaces the filter velocity (air to cloth ratio) has to be kept