Wet boron removal
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Does anyone know anything about wet boron removal in polysilicon production? Could you talk about it?
It involves introducing moist nitrogen during the distillation process; the small amount of water present in this nitrogen reacts with the material and impurities, thereby changing the form in which boron exists and allowing it to be removed. This post was last edited by zjiris on 2009-2-24 at 15:16.]
The key is to know in what form boron exists in silicon. In its elemental form, B reacts only with oxidizing acids such as nitric acid and sulfuric acid; if it is in the form of boron oxide, both acids and bases can be used to remove it
If the small amount of water present in nitrogen reacts with trichlorosilane, wouldn’t it produce the hydrolysis product SiO2.H2O? A blocked pipe? What is the effectiveness of wet method boron removal? Are there any technical indicators? What are the specific indicators? Can it meet the standards?
This method is applicable to the modified Siemens method.:)
It’s not a hydrolysate; it’s a complex that adheres to the tower closure and requires regular cleaning. As for the specific parameters, it’s hard to say
Clean the distillation tower regularly? Has our distillation tower remained unused for almost 4 years since it was installed? ! How to clean it regularly? Besides, must this complex be attached to the tower closure? Won’t it enter the pipeline with the material?
Reply to 3# hanshihhh: Bro, I just have to say something about you. Currently, in China, boron and phosphorus are removed from polysilicon in the form of boron and phosphorus chlorides; there is no such thing as removing them in their elemental form. There’s no need to use acids or bases either. The idea of removing elemental boron and phosphorus only exists in the fluidized bed process used exclusively in Japan and the United States
Reply to 7# feibiao101: You are not using reactive distillation with wet boron removal in the secondary distillation section, so there is little complex attached to the tower walls. Wet boron removal is employed; the boron complex adsorbs onto the hydrolysis products of trichlorosilane, thereby adhering to the tray surfaces and tower walls. Generally, a spare tower is provided, which is washed with NaOH once a year.
Reply: 9# blackstonepxj is right; wet boron removal does not involve removing elemental boron, but rather converting boron into compounds with high boiling points, which are then removed at those high temperatures.