SPAM - concreting in space

> TangoMan
>
> I was responding specifically to the idea of building a habitat
out
> of concrete or aluminum
>
> Anorthosite is a rock not a mineral
> Anorthosite is a mixture of other crystalline minerals;
> Anorthite or calic-feldspare - Ca(Al2Si2O8)
> Pyroxene - (Mg,Fe)SiO3
> Olivine FESiO4

Thanks for the above clarifications. I'll try to keep my terminology
accurate :)

>
> Since we don't have limestone, Anothosite would be a good choice
of
> rock for extracting calcium. And it is farley common on the
moon.

Yes, especially in the Lunar Highlands.

> Now if we have a sample of this rock and we melted it we would
have
> molten anorthosite and when it solidified we would have a fine
> crystalline anorthosite.

I'm following you so far.

In order to get calcium or aluminum out of
> the melt you would need use electrolysis and that would require
shirt-
> loads of electricity.

Shirt-loads ? :) Don't you mean, well, ah, you know :)

The relative free energy needed to separate
> oxygen from metals varies from metal to metal.

I've uploaded this graphic to the Files section in the hopes that it
is relevant to our discussion.

http://f4.grp.yahoofs.com/v1/sGM0P3h-
1UhYGteNYNQoGBRH8OqY8C7TrG9FjMMCaj97g9waXXL9CX37nWxXPNweZLqH8Bq4vtGG3
gry4nOcb-PpIBzUDknB_yuGcA/Energy%20Requirements%20for%20Breaking%
20Lunar%20Oxides.jpg

You can unwrap the above URL and paste the entire thing into your
web browser or just go to the YahooGroups website and in the Files
section click on the file entitled:

Energy Requirements for Breaking Lunar Oxides.jpg

The process of
> electrolysis will remove the weaker bonded metals first such as
iron,
> potassium, phosphorus and Silicon.

Are we both on the same page here? Doesn't the energy requirement
for electrolysis refer to breaking the oxide bonds to seperate the
metal from the bound oxygen.

Surely the energy requirements would be considerably less for
extracting the oxides of calcium, silicon and aluminum from the
anorthite or feldspar?

A typical portland cement consists of 65% CaO, 23% SiO2, 4% Al2O3.
How much energy would be required to break the anorthite into these
constituent oxides?

The most difficult metals to
> separate are Al, Mg, and finally Ca. I have to be honest in that
I
> don't know why we would go though this to obtain lime for
concrete.
> If you need aluminum for wiring for your habitat, it would be
worth
> it. If you need mass quantities of aluminum for the pressure hull
it
> would not be worth it.

I'm in agreement with you on this point. Even though solar energy
will be free for the taking, it'll still require infrastructure to
use it.

Aluminum production is very energy intensive so that detracts from
it's merits.

Now processing ilmenite will yield Iron, Titanium and Oxygen.

Perhaps the Titanium can be used for the pressure hull because of
its light weight and high tensile strength. The Iron can be used
for the construction of SPS where it's mass won't be subjected to
centripetal forces and it's tensile strength would be irrelevant in
a Zero-g environment.

The Oxygen is used for the Habitat atmosphere and for propulsive
oxidizer.

Finally, after the Habitat shell is constructed, perhaps the
anorthite is now finally processed. Energy will be more readily
available becasue of the orbiting SPSs.

The anorthite will yield alumium which we may use in our Habitat
building construction in order to lessen building loads on the
pressure hull. Surely this would be better than iron girders.

The remaining silicon oxides and calcium oxides can be used for
Habitat internal ground cover and radiation shielding.

Thus all of the constituent parts of ilmenite and anthorite are
directed to specific purposes.

Having said all of the above, I'm still not sure about the metal-
concrete debate for Habitat shell construction.

> Lets talk about ductile iron. We humans have allot of experience
> building things with iron. Because the Moon is a reduced
> environment, there exists, native Iron in the soil. It could be
> separated using a magnet. Iron also exists in ilmenite that can be
> reacted with H2 to product native iron and TiO2. the H2 is
> recyclable and the TiO2 is Ore quality.
>
> Producing Iron will require considerably less energy than
aluminum.
> I don't believe that that there will be an unlimited amount of
energy
> on the moon. So, yes cost is relative, but aluminum on the moon
does
> not compete with aluminum from earth. I am comparing the cost in
> energy compared with other lunar materials.

Good point, but wouldn't you have to cover a lot of lunar area to
find the native iron in the soil?

> The molten basalt idea is intriguing because it only requires heat
> which is much easier to come by than electricity.
>
> more

Looking forward to more.

TangoMan