A bold idea: is it possible to produce metallic silicon or polycrystalline silicon from amorphous SiO2?

That’s fanciful thinking – polycrystalline materials are not produced in that way. They are formed through the reduction of liquid trichlorosilane and hydrogen, and extremely high purity is required, ranging from 6 nines to 9 nines

Hehe, I know that polysilicon is produced by reacting industrial silicon with chlorine to form trichlorosilane, and then trichlorosilane reacts with hydrogen to produce silicon. I’m just curious whether amorphous SiO2 can be processed to produce crystalline industrial silicon, which could then be used as a raw material for polysilicon:loveliness: :loveliness:

It’s a great idea, but unfortunately the purity isn’t high enough! !

Insufficient purity? I think it’s still the limitation related to crystal structure; the key issue is how to convert amorphous SiO2 into crystalline SiO2. As long as it can be turned into crystalline SiO2, a electric arc furnace can be used to extract metallic silicon from silica ore (with a purity of >99%), and then metallic silicon can be used to produce polycrystalline silicon I have been thinking about this issue lately; I hope everyone will participate actively in the discussion

Amorphous silicon can also be used in solar cells, but the technology is not yet mature. I boldly predict that plants using the Siemens method to produce SG-grade polysilicon will reach a dead end within less than 10 years. Too high a cost, too much pollution; it comes fast and goes fast!

You’ve reminded me of this. Although it’s very difficult to produce polysilicon from amorphous SiO2, it is possible to produce amorphous silicon from it, and this can also be used in solar cells. It could be considered a way to make better use of silicon. However, it seems that there isn’t much research on this topic in China at the moment:loveliness: :loveliness: :loveliness:

A hypothesis that violates basic chemical principles. If Si can be proposed, there is another way to do it as well

Theoretically, it’s possible, but the purity of the reduced carbon required is very high. Isn’t there already a metallurgical method for producing polysilicon?

Metallic silicon? Calling it that for the first time—

Metallic silicon, also known as industrial silicon, has a purity of around 99%. Aren’t the raw materials used for producing polysilicon all derived from industrial silicon (metallic silicon) with a purity of around 99%? I just went to inspect Tianwei Yingli’s solar production plant, and the level of secrecy there is truly strict! Only the polysilicon solar cell modules were visible; nothing else could be understood: L

White carbon black is also derived from crystalline SiO2; even white carbon black produced by precipitation methods is much more expensive than silica sand, not to mention vapor-phase white carbon black. White carbon black also contains water, trace acids, or salts

It’s a typical case of satellite posting – friend on the 17th floor, please share your methods. If polycrystals are to be produced directly from silicon tetrachloride, then the raw materials would cost nothing at all. There are so many factories across the country, yet their conversion processes are terrible; they can’t even handle silicon tetrachloride properly. It might be possible to mix SiCl4 with SIHCl3 for production, but producing polycrystals directly using only SiCl4 is completely impossible – it doesn’t comply with the thermodynamic requirements of the SI-H-CL ternary system. Unless it’s converted into SIHCl3 first. I’m not very knowledgeable; this is just my personal opinion. Experts, please give me some guidance

As far as I know, the SiCl4 produced by domestic polysilicon plants is not recycled; instead, it is sold directly to downstream manufacturers. It is said that it is used in the production of vapor-phase silica, but the amount used is very small, making it difficult to utilize all the SiCl4 generated as a by-product in polysilicon plants. It seems that it is quite difficult to produce polysilicon from SiCl4; if it were easy, why would those polysilicon manufacturers still sell SiCl4?

Academician He Zuoxiu of the Chinese Academy of Sciences discusses energy issues: He Zuoxiu: Currently, people are generally focusing on three approaches. The first method is called the Siemens improvement method; I’ll just mention the name. The second method is called the silane method. The third method is called the metallurgical method. It is widely recognized that the metallurgical method has the potential to significantly reduce costs. Of course, there are also various different metallurgical methods. Guo Tongxing: Can it be understood in this way that, as the name implies, the metallurgical method could be used to extract monocrystalline silicon by means of metal smelting? He Zuoxiu: More or less that’s the meaning. The silane method involves converting silica into silane, that is, into silicon compounds, and it is a very complex process. The Siemens process for converting it into a chloride is a more complex chemical process. Why could new refining methods potentially lead to significant price reductions? In the early years, the Siemens method was used to produce single-crystalline silicon with a high degree of purity, reaching 9 nines or even 11 nines. However, research has shown that 6 nines is sufficient for silicon used in solar cells, and it is possible that metallurgical methods can meet these requirements. This is relatively simple. In that case, costs could be reduced significantly. I don’t want to evaluate the advantages and disadvantages of these methods from a personal perspective here. But it has various ideas to try and reduce costs. Currently, international market prices have soared, reaching 200 dollars per kilogram. I believe that with future technological advancements, it will be possible to sell it at 20 dollars or even 15 dollars per kilogram – that’s entirely feasible. http://tech.qq.com/a/20061220/000280_5.htm

Silicon powder is already very expensive nowadays; even if the price of polysilicon drops further, it won’t be able to return to its previous levels.

Of course it’s possible, it’s just not feasible.

It seems to be much more expensive than silica, right? Silica costs only 300 yuan per ton, and in desert areas it’s almost free. Theoretically, white carbon can be used to produce metallic silicon, but due to its low density it cannot be smelted directly; it needs to be melted into particles or blocks first, which makes it less advantageous compared to using silica directly. Incidentally, that certain academic who keeps making grand claims reminds one more of an entertainment star than a scientist %$&%! Moreover, silicon tetrachloride has a very low silicon content, is a hazardous substance, and is difficult to transport; using it for silicon production might not be worth the effort.

There are many types of silica, and the prices of different products vary greatly. In addition to the crystal form issue, there are also problems related to particle size and particle size distribution; high-quality silica gel also needs to be modified by coating it with organic substances to achieve rheological properties. The poster’s idea makes sense; from a chemical perspective, there are countless possibilities. The key is to determine which method is more cost-effective. For example, if a one-step process requires extremely high temperatures and pressures of several thousand degrees, then it’s necessary to figure out what kind of equipment would be needed to carry out such a process. The cost is too high.

I believe that from an economic perspective, silica is likely to be uneconomical; technically, amorphous silicon can be converted into crystalline silicon, or it can remain in its amorphous form. However, due to China’s abundant silicon resources, the main cost associated with producing chemical silicon does not lie in the raw materials, but rather in energy consumption.

It is not impossible to convert metal-grade silicon directly into solar-grade polysilicon; in fact, it is quite possible. There are studies being conducted both domestically and internationally, and there are also examples of industrial implementation. What is Little Coal Ball used for? It’s a great and practical idea – thumbs up!