Usually metallic fluorosilicates are reacted with Ca/Na/K etc metal or alloys to obtain fluoride salts and silicon. But These metals are not very easily produced other than electrolysis. Is it possible to reduce H2SiF6 chemically or with aid of electrolysis rather than their metallic salt? Can cheap reductants like Hydrogen/Carbon/Hydrocarbon do the job? (I do not know redox potential of hexafluorosilicate ion).
By the way, the reactant is from fertilizer industry, and Si is to be used in electronics.
Dear Sumit Bhowmick ,
You can decompose H2SiF6 by heating into HF and SiF4 you can separate them by fractional distillation.
Then you can extract silicon by reducing SiF4 at high temperature into suitable reactors as:
SiF4 +2H2 = Si + 4 HF
Best wishes
Dear Abdelhalim abdelnaby Zekry ,
According to FactWeb (https://www.crct.polymtl.ca/factweb.php), I get following at 3000K and 1 atm.
SiF4 + 2 H2 = 3.9305 mol gas_ideal (108.11 gram, 3.9305 mol, 967.59 litre, 1.1173E-04 gram.cm-3) (3000 K, 1 atm, a=1.0000) ( 0.39132 HF + 0.27167 H2 + 0.12460 SiF2 + 0.10381 SiF3 + 8.1867E-02 H + 1.3181E-02 SiF4 + 9.4171E-03 SiF + 2.2726E-03 Si + 9.3640E-04 SiHF3 + 7.2761E-04 F + 1.6698E-04 SiH + 2.6231E-05 SiH2F2 + 5.5487E-06 Si2 + 8.1007E-07 (HF)2 + 2.5289E-07 SiH3F + 3.1723E-08 Si3 + 9.8177E-10 SiH4 + 8.2682E-11 F2 + 2.5818E-12 H3F3 + 2.0473E-17 H4F4 + 6.7752E-18 Si2H6 T + 1.4175E-22 H5F5 + 1.3681E-27 H6F6 + 4.6660E-33 H7F7) + 0 mol Si_liquid (3000 K, 1 atm, L1, a=2.1339E-02) + 0 mol Si_solid T (3000 K, 1 atm, S1, a=4.7111E-03)
Thermal decomposition seems rather difficult here.
Best Regards,
Henri.
Dear Sumit Bhowmick many thanks for your very interesting technical question. In this context please have a look at the following relevant research paper. In this study the author used fluorosilicic acid (H2SiF6) produced in Iraqi Fertilizer plants as inexpensive raw material. Simple treatment of the free acid with potassium chloride (KCl) produced potassium fluorosilicate (K2SiF6), which was then electrolyzed to give elemental silicon.
Electrodeposition of Silicon from Fluorosilicic Acid Produced in Iraqi Phosphate Fertilizer Plant
Article Electrodeposition of Silicon from Fluorosilicic Acid Produce...
The article is freely accessible as public full text on RG.
- Badges
- Science topic
- Similar topics
- Chemistry
- Sulfites
- Inorganic Chemistry
- Inorganic Chemicals
- Salts