I know reduction reaction of Silica with carbon, also principle of Zone refining or single-crystal generation process. I also heard of silicon chloride purification process,But I know not ore dressing, beneficiation and pretreatment of silica as well as preliminary purification of silicon (say from 80% Si to 99.9% Si). Please inform me and refer to suitable research
I studied the extraction of electronic grade silicon from silicon dioxide white sand.
These steps are used:
- The raw materials are white sand from mines with high purity such that one do not need a preparation steps to reduce the cost. In addition to carbon and chip woods.
- Then one extracts a metallurgical grade silicon by running the reduction process an metallurgical electric arc furnace. One gets silicon blocks with purity as low as 98 percent.
- Such silicon is purified by the fractional distillation as in Waker Chemietronics.
where one gets pure compounds of silicon such as SiCl4,....... SiH4.
- Then one uses the so called Siemens process to get pure Si rods.
- Then this rods are crystallized by zone refining or pulling from an ingot Silicon melt.
Best wishes
In order to follow the details of these processes please refer to the book of S MSze, VLSI technology.
I think there is no preparation step for the quartzite.
The most important thing that one selects relatively pure quartzite ore.
Even the purity of the commertial silicon will be worse than tat of the quatrzite ore.
May be there are advanced processes other than this classical process.
Best wishes
I studied the extraction of electronic grade silicon from silicon dioxide white sand.
These steps are used:
- The raw materials are white sand from mines with high purity such that one do not need a preparation steps to reduce the cost. In addition to carbon and chip woods.
- Then one extracts a metallurgical grade silicon by running the reduction process an metallurgical electric arc furnace. One gets silicon blocks with purity as low as 98 percent.
- Such silicon is purified by the fractional distillation as in Waker Chemietronics.
where one gets pure compounds of silicon such as SiCl4,....... SiH4.
- Then one uses the so called Siemens process to get pure Si rods.
- Then this rods are crystallized by zone refining or pulling from an ingot Silicon melt.
Best wishes
In order to follow the details of these processes please refer to the book of S MSze, VLSI technology.
I think there is no preparation step for the quartzite.
The most important thing that one selects relatively pure quartzite ore.
Even the purity of the commertial silicon will be worse than tat of the quatrzite ore.
May be there are advanced processes other than this classical process.
Best wishes
Dear Sumit Bhowmick
The electronic-grade Si (EGS) of 1ppn (99.9999999%) purity is obtained from quartz (raw SiO2) in a number of standard steps. I conclude these as follows:
1- The metallurgical-grade Si (MGS) of about 99% purity is first obtained from Silica, usually by carbon reduction. The MGS purity is not adequate for Si devices and integrated circuits. So it needs additional purification steps
2- The MGS is transformed to volatile liquid, such as SiCl4, SiCl3H, SiCl2H2 and SiH4. For instance:
MGS + 3HCl → SiHCl3 + H2
3- We use the the Siemens process ,to get Poly Si rods from such compounds
4- Poly Si is then crystallized by many methods, among them I an cite the most famous ones:
i- Chocarlesy (CZ) method (cystall pulling)
ii- Floating zone (FZ) method (zone refining).
There exist so many Books and Websites such as SemiWiki to get more detailed information. https://en.wikichip.org/wiki/electronic-grade_silicon
Sumit Bhowmick
I heard that dressing the reducing agent is also common to decrease the impurity content of metallurgical grade silicon, for example, bark is removed from trees to obtain purer woodchips.
Also, washing of quartzite can be carried out. Probably more important is the selection of raw materials. Quartzite with quality issues is rejected as can be seen in this paper.
https://www.pyro.co.za/InfaconVI/1185-Szymkowski.pdf
I also heard, that using iron lances to open the taphole could be a source for iron impurities. Opening the tap hole with a shotgun could be an option to avoid impurities from lancing, but I don't have a source at hand for this.
Further refining is already explained in the previous answers and also various reviews about refining metallurgical grade silicon are available:
Article Refining and Recycling of Silicon: A Review
https://www.tandfonline.com/doi/abs/10.1080/08827508.2018.1459616?src=recsys&journalCode=gmpr20
Article High-Temperature Refining of Metallurgical-Grade Silicon: A Review
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