Karls Geopolymer Experiments

[Deleted]

Magnesium analogues of aluminosilicate inorganic polymers (geopolymers) from magnesium minerals.
www.researchgate.net/profile/Kenneth_Mackenzie3/publication/258798067_Magnesium_analogues_of_aluminosilicate_inorganic_polymers_geopolymers_from_magnesium_minerals/links/0deec5296ac49d1eb8000000.pdf

Finaly I have found the full paper.

Sepiolite and chrysotile seem to work quite well,
but talc proved to be extremely resistant to geopolymer synthesis.
You could try to get some calcined sepiolite .

Chrysotile is the most commonly encountered form of asbestos.
The paper has a wrong chemical composition for chrysotile.
Antigorite and lizardite with the same chemical composition as chrysotile,
but different arrangement are not fibrous.

Cordierite has many of the advantages of soapstone, but is more wear resistant.
You could try to get cordierite grog or add some caustic burned magnesite
to a geopolymer mixture to get a cordierite like geopolymer.

As caustic burned magnesite is commonly used by potters it should not be hard to get some.

Effect of Reactive Magnesium Oxide on Properties of Alkali Activated Slag Geopolymer Cement Pastes.
www.i-asem.org/publication_conf/acem14/5.AMR/T4E.7.MR353_587F.pdf

Not a geopolymer in the technical sense:
Talc as raw material for cementitious products formulation.
ac.els-cdn.com/S2187076414000554/1-s2.0-S2187076414000554-main.pdf?_tid=03f11ffa-535b-11e6-a506-00000aacb35d&acdnat=1469556285_5d8e66d765e77746095357873c52df43

[keithturtle]

Source for talc

www.fibreglast.com/product/talc-filler-1131/Fillers

I use this stuff in resin for casting wind turbine components

Would there be any merit in adding it to my [1 portland / 1 fireclay / 2 sand / 4 perlite] mix for castable refractory?

Turtle

[Deleted]

Talc is soft and will make any cementitious composition less rigid.
Magnesium has a higher specific heat than aluminium.

Heat is basically vibration on atomic and molecular level.
It requires more energy to let a soft material vibrate,
than is required to let rigid materials vibrate.

The combination of magnesium content and softness
gives talc a high specific heat.

A high specific heat is not desirable for fire box and riser,
but very desirable for heat storage

[Deleted]

Magnesium oxide serves as crystal growth inhibitor in ceramics,
thus improving fracture toughness and resistance to thermal cycling.
Talc decomposes at about 900°C to free magnesium oxide, free silica and water.
Magnesium oxide and alumina silicates may sinter to cordierite.

[Deleted]

I have made a reverse side temperature test with a small soldering torch.

Two 17mm thick plates made from dense grog with 43% alumina with 10% lye and 10% cement.
1.) With high water content and a few gram of short basalt fiber to make the mixture thicker,
prevent segregration while liquid and prevent cracks while drying.
Density 1.5g/cm³.
2.) With lower water content and filled with fine slag sand.
Density 1.93 g/cm³.

For each one I have heated a spot of about 1.5 cm to an orage to yellow orange glow,
which according to a Kiln Firing Chart equals 1000°C - 1100°C.
About 4 cm above the temperature was fallen to about 750°C,
which is the highest temperature my IR-Thermometer can measure.

For the lighter plate the reverse side temperature reached 180°C.
For the denser plate the temperature was a bit lower,
but the hot spot was significantly larger, as the temperature was more evenly distributed.

Judging from this I cannot see much sense in weakening the structure
by adding large amounts of sawdust or perlite/vermiculite particles of a recognizable size.

[Deleted]

The Potential of Geopolymer as High Quality Refractory
www.researchgate.net/publication/291953832_The_Potential_of_Geopolymer_as_High_Quality_Refractory

The results of the paper above are consistent with my findings.
They have thrown a lot more heat against about three time bigger pieces.
The piece with the highest alumina content has the lowest thermal conductivity,
but the difference is very small.
20-25mm should provide a more than sufficient temperature gradient even for a heat riser.

Some theoretical background:
Thermal Conductivity of Metakaolin Geopolymers Used as a First Approximation
for Determining Gel Interconnectivity
www.researchgate.net/profile/Jannie_Van_Deventer/publication/231373810_Thermal_Conductivity_of_Metakaolin_Geopolymers_Used_as_a_First_Approximation_for_Determining_Gel_Interconnectivity/links/0deec52c9f66dc6562000000.pdf

[firewatcher]

With all of the rain today making it a little more bearable to work outside, I was finally able to complete my ball mill...


Testing will commence when i pick up some zeolite (hopefully in the next week) and I'll post some results.

[Deleted]

150 RPM ?
You could test it with your agricultural perlite.
I do not like to wait.

[firewatcher]

I did a rough estimation (counting revolutions) and I ended up with about 120 RPM...the inside groove of the pulley is a fair amount smaller than the outside diameter.  Unfortunately I don't have a set of calipers to get the correct measurement on the "groove" of the pulley to do an actual calculation.

Actually you don't have to wait..I've already tried the perlite (I hate waiting too)...and running the rig for about 10 minutes pulverized the agricultural grade perlite (coarse) to a very fine powder.  I'm going to try and set aside the time tomorrow to empty the rest of the barrel and see if a picture will show how fine it is.  I did compare a small sample crushed in the mill to what I had put through a blender and they seemed to be very comparable.

From a cost and availability perspective, the zeolite still seems to be my better option, so I want to see how well (or not) the mill works on it.

[Deleted]

Mill Speed - Critical Speed
www.pauloabbe.com/size-reduction/resources/mill-speed-critical-speed

According to the site above the optimal speed for you mill would be about 60 RPM.
Higher speeds may cause cataracting which will generate high impact but also greatly increase mill wear.
Cataracting would be desirable for mechano-chemical activation of clays.
High impact energy can change the particle structure from crystalline to amorphous,
and may even cause dehydration.

Ball Mill Critical Speed & Working Principle
www.youtube.com/watch?v=L6sgGXXYdEU


Clinoptilolite has a hardnes of 3.5-4,
thus should be no problem.

[firewatcher]

I did some reading on ball mills and saw the video that you shared as well. Unfortunately I'm trying to get away with using the materials that i have, so I'm glad to hear that my setup will work out regardless not having an optimal setup. Thank you once again for all of the helpful information that you share...and as i had hoped to provide today, here are the pictures of the two "versions" of powderized perlite:

On the left is the perlite from the ball mill...on the right is perlite powderized in the blender...


...a slightly closer up pic of the powder from the mill...


...and slightly closer up pic of the powder from the blender...


There is a slight color difference between the two (don't know how noticable it is in the pictures)
...the powder from the mill has a slight brownish tint to it due to the tan colored paint on the inside of the drum.

[lawry]

Good work on the mill firewatcher! please do a video of the mill in action when you get the chance.

I found some milled clinoptilolite and tried casting it. It didn't work out so well. It didn't set at all until I put it in the sun on a black surface. And it's still not fully set in over a month. It could be my mix ratios.

[firewatcher]

Aug 18, 2016 6:03:20 GMT -8 lawry said:

Good work on the mill firewatcher! please do a video of the mill in action when you get the chance.

I found some milked clinoptilolite and tried casting it. It didn't work out so well. It didn't set at all until I put it in the sun on a black surface. And it's still not fully set in over a month. It could be my mix ratios.

I'll try to do a video in the next couple of days and post it.

With regard to your clinoptilolite casting...what is "milked" clinoptilolite or is it a typo and supposed to read "milled"?
Did you mix it with anything else?

I'd need Karl to confirm, but i thought that micronized clinoptilolote was supposed to be used in the same "mix" that Karl had defined using micronized perlite (45% micronized perlite, 45% clay, 10% lime/hydrated lime...%'s by weight). To this mixture you add enough sodium silicate to make it the consistancy of cream and then add aggregate if you choose.

I could be mistaken...will need Karl to comment.

[lawry]

I have been struggling to cure my experimental castings in the winter temperatures. I took a black plastic nursery plant container and covered my small samples. I was pleasantly surprised when I measured the temperatures... See below

So I made a sheet metal box and painted it black for my firebox. It really sped up the curing. Should be better now in summer. See below

Firewatcher I cast another firebox from FA. It's came out ok. But problem is that the inside part of the firebox doesn't wanna come out. So i am going to have to burn it and lose my mould. This is sad.

[Deleted]

Aug 18, 2016 6:51:49 GMT -8 lawry said:

But problem is that the inside part of the firebox doesn't wanna come out.

Did you made the form obliquely ?