Device and method for recovering silicon dioxide after burning waste gas and waste liquid in polycrystalline silicon industry

Abstract

The invention relates to a device and a method for recovering silicon dioxide after burning waste gas and waste liquid in polycrystalline silicon industry. The method comprises the following steps: after equipment is installed and connected, a smoke inlet control valve on a smoke conveying pipeline is switched on, so that high-temperature smoke enters a metal filter element type filter, powder isblocked by a high-temperature-gas filter element, and conveyed to a powder collector by negative pressure, power collected by the powder collector enters a degassing unit for degassing, the degassed powder is packaged into a finished silicon dioxide bag by a sealing packaging machine; when a filter works for a period of time, a back flushing gas storage bag and a back flushing valve are started, a back flushing gas pipe installed in the metal filter element type filter is used for back flushing the high-temperature-gas filter element from inside to outside; and after the back flushing is finished, the high-temperature-gas filter element is in back flushing for cleaning. In the invention, the waste gas and waste liquid are processed intensively to achieve the environmental protection requirement, simultaneously, gas-phase silicon dioxide is recovered effectively, industrialization is formed, and high economical value is created.

Description

technical field [0001] The invention relates to the field of polysilicon, in particular to a device and method for recovering silicon dioxide by dry method after incineration of waste gas and liquid in the polysilicon industry. Background technique [0002] High-purity polysilicon is an important basic raw material for the development of microelectronics industry and solar energy industry today. It is a high-tech product that spans multiple disciplines and fields such as chemical industry, metallurgy, machinery, and electronics. [0003] At present, with the rapid development of the global microelectronics industry and photovoltaic industry, especially driven by the strong photovoltaic industry, the domestic polysilicon market has been in short supply. For this reason, polysilicon heat has been formed in China in recent years, and many large polysilicon projects have been launched or will be launched soon. According to incomplete statistics, there are more than 60 polysili...

AI Technical Summary

Problems solved by technology

[0008] Although the hydrolysis alkali absorption method can treat the waste gas and waste liquid in the polysilicon production process, and can convert toxic chlorosilanes into harmless substances, it also produces a large amount of waste water and waste residue, especially the large amount of alkali consumption. Easy slagging leads to abnormal operation of the equipment and great environmental pollution

[0009] (2), using conventional milk of lime Ca(OH) 2 Neutralization precipitation method: due to the high solubility of calcium chloride in water, chloride ions still exist in the water, and the treated water contains salt water, which cannot be discharged, resulting in poor treatment effect

[0010] Due to the large amount of lime added, the site needs a large area for stacking lime and dissolving lime, so that waste gas and waste liquid treatment need to occupy a larger site, and the site operating environment is very poor

[0011] (3) Neutralization and precipitation plus reverse osmosis method: Although the effect is good, the chlorine ion concentration in the wastewater produced by the final concentration is higher, and it is more difficult to deal with the standard

[0012] (4) Neutralization precipitation plus evaporation crystallization method: Although the method is good, but the processing capacity is large, the investment and operation costs are too high, and the energy consumption is also high, which is difficult for general projects to bear, and chlorine is discharged in the form of slag without recovery

[0014] Although the incineration wet treatment technology has advantages compared with the traditional hydrolysis alkali absorption technology and has been adopted abroad, it also has serious defects: it has no recovery function for materials and waste heat, resulting in a waste of resources

[0015] The above-mentioned situations are the status quo of comprehensive treatment of chlorosilane waste gas and waste liquid in the domestic polysilicon industry, which seriously restricts the healthy development of this industry

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