clearly_not_atara
International Hazard
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sorel cement production process
http://en.wikipedia.org/wiki/Sorel_cement
Sorel cement is a magnesium-based cement which has the unique property of binding to wood. However it is made with magnesium chloride which is
expensive, and it is slowly corroded by water, and the additives which prevent this are soluble silicates and phosphates, which are expensive. So I
came up with this modified Solvay process, using magnesium carbonate, a common magnesium ore:
NaCl (aq) + NH3 + CO2 + H2O >> NaHCO3 (s) + NH4Cl (aq)
2NH4Cl (l) + MgCO3*3H2O (l) + heat >> MgCl2 (s) + H2O (g) + CO2 + 2 NH3 (g)
2NaHCO3 + heat >> H2O + CO2 + Na2CO3
Na2CO3 + SiO2 >> Na2SiO3 + CO2
http://en.wikipedia.org/wiki/Sodium_silicate#Production
Inputs are salt, silica (sand?), heat and magnesite, and the products are MgCl2 and sodium silicate, the crucial components of Sorel cement, so I
thought you could take advantage of a beach somewhere with a solar heat collector (mirrors).
Also I'm bored enough to be thinking of this stuff :p
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clearly_not_atara
International Hazard
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I keep losing this patent. I am slightly confused because some of the patent literature says that sodium silicate is too expensive to be practical but
alibaba says it costs less than $200/ton at which point most of the cost probably comes from moving it around. Anyway I'm saving this patent.
https://www.google.com/patents/US3667978
and this paper:
http://www.ingentaconnect.com/content/ccs/jccs/2012/00000040...
notably:
"The Earth′s mantle is roughly 70% magnesium orthosilicate (Mg2SiO4), and this occurs as surface deposits in the form of olivine.
Partial hydration of such rocks near the Earth′s surface usually leads to the formation of serpentine (Mg3Si2O5(OH)4). Since neither of
these minerals contains fossil CO2, the main industrial problem is how to efficiently extract reasonably pure MgO from them with
acceptably low costs and CO2emissions associated with the energy used. Novacem′s approach is to make use of supercritical carbonation in a
high-pressure reactor. This decomposes magnesium silicate into magnesite and amorphous silica, which can, if necessary, be
separated."
Mg2SiO4 + 2CO2 (sc) >> 2 MgCO3 + SiO2
actually fits right into the original posted process... so now you only need salt and olivine (although this supercritical carbonation might prove not
to be efficient).
[Edited on 16-8-2017 by clearly_not_atara]
[Edited on 16-8-2017 by clearly_not_atara]
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clearly_not_atara
International Hazard
Posts: 2692
Registered: 3-11-2013
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Okay, now I think I have a real idea. Fluorosilicates are important, right? But all fluorosilicate production works via hydrofluoric acid, which is
corrosive and toxic. I think this can be avoided:
3CaF2 + SiO2 + 2 CO2 (supercritical) >> 2 CaCO3 + CaSiF6
I'm not sure if this happens at an achievable CO2 pressure, but it would be a step forward if it does. How do you predict these sort of reactions?
And has anyone ever build a supercritical CO2 apparatus at home? I'm guessing no.
I'm also not sure how to convert the calcium salt to a sodium salt, or if that's really necessary (both salts have low solubility).
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