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Author: Subject: Calcium Silicate from concrete rubble?
nikotyna1939
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[*] posted on 12-3-2024 at 09:17
Calcium Silicate from concrete rubble?


Is it possible to extract and purify Calcium Silicate from concrete rubble in the range 90 to 98 percent in purity?




[Edited on 12-3-2024 by nikotyna1939]
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bnull
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[*] posted on 12-3-2024 at 11:44


No. Concrete is made of cement, which is mainly calcium silicates and aluminates (and carbonate, of course). You can't separate them physically because the particles or whatever are very small, well mixed and in the solid state. They don't melt without decomposing and they're also insoluble. You can't separate them chemically without destroying them.

You would have more luck synthesising it. Buy sodium silicate and calcium chloride, make solutions of each, mix them in the right proportion and, lo and behold, your own high purity calcium silicate.




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nikotyna1939
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[*] posted on 12-3-2024 at 14:57
Route by dissolving concrete rubble in HCL to get Calcium Chloride?


What if I dissolve concrete rubble to get Calcium chloride first and purify it and after that reacting the Calcium Chloride with Sodium Silicate?
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nikotyna1939
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[*] posted on 12-3-2024 at 15:02
Concrete + HCL= products ?


What is the formula products of the reaction betwen Concrete + HCL ?
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nikotyna1939
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[*] posted on 12-3-2024 at 15:09
Calcium Chloride substitute?


Can i use Calcium Sulfate as a substitute for the Calcium Chloride?
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[*] posted on 12-3-2024 at 15:19
The main reasons of using concrete rubble


I'm going to use concrete rubble because I BELIEF IN THE 3R PHILOSOPHY REUSE, REDUCE AND RECYCLE!

Also to reduce monetary budgets.



[Edited on 12-3-2024 by nikotyna1939]
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[*] posted on 12-3-2024 at 16:27


If you use CaCl2 and Na2SiO3 you get a basic calcium silicate of fluctuating composition. CaSO4 is almost insoluble in water, very slightly soluble in H2O, so it is hardly a substitute for CaCl2. Truly pure calcium silicate of solid composition can be obtained by fusing a stoichiometric mixture of SiO2 and CaCO3 (CaO) at high temperatures, just over 1400 C.
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clearly_not_atara
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[*] posted on 12-3-2024 at 18:39


You can just buy wollastonite IIRC



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[*] posted on 12-3-2024 at 20:01


Quote: Originally posted by nikotyna1939  
What if I dissolve concrete rubble to get Calcium chloride first and purify it and after that reacting the Calcium Chloride with Sodium Silicate?


It's possible. But concrete rubble will dissolve very slowly, so best to grind the rubble to a powder first.

Quote: Originally posted by nikotyna1939  
What is the formula products of the reaction betwen Concrete + HCL ?


Depends on the composition of the concrete - calcium, aluminium and iron chlorides can be expected.

https://www.sciencedirect.com/topics/materials-science/portland-cement#:~:text=Portland%20cement%20(OPC)%20consists%20of,continuous%20compact%20mass%2 0of%20masonary.

Quote: Originally posted by nikotyna1939  
Can i use Calcium Sulfate as a substitute for the Calcium Chloride?


Possibly, but calcium sulfate isn't very soluble (approx 2 g/litre), however it is much more soluble than calcium silicate (< 0.1 g/litre). So if you dissolve approx 1 g calcium sulfate in 1 litre of water, then react with sodium silicate, if you see the solution going cloudy you can tell it's working.

Quote: Originally posted by nikotyna1939  
I'm going to use concrete rubble because I BELIEF IN THE 3R PHILOSOPHY REUSE, REDUCE AND RECYCLE!

Also to reduce monetary budgets.

[Edited on 12-3-2024 by nikotyna1939]


Unfortunately, when you take into account the cost of the hydrochloric acid and the other chemicals as required, it won't save money or resources. Best use for old concrete rubble is as hardcore (as a component of construction aggregate).



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nikotyna1939
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[*] posted on 12-3-2024 at 23:10
The other reasons of not just buy calcium silicate


I don't just buy calcium silicate because in my area you need to buy calcium silicate in bulk quantity like 100 kg to get a reasonable price.

also i needed only about 10 kg only.
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[*] posted on 13-3-2024 at 00:20


How commonly available is calcium silicate from silicate bricks - new bought, demolition rubble or building leftovers?
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[*] posted on 13-3-2024 at 04:40


@nikotyna1939: Forgive me the question but, why do you need 10 kg of it? Depending on the use, you can find something even better and easier to get. Or you can buy the sodium silicate and the calcium chloride and make your own. I know that you'll get a "basic calcium silicate of fluctuating composition". Even so, if the requirements are for a generic calcium silicate, never naming one in particular, you'll be in the same ballpark as concrete.

Try to find some rice farmer who buys it in bulk and try to buy some from him. If he has a 1000 kg stockpile, for example, 10 kg will be peanuts for him. I don't know how much he will charge you. And if you're a rice farmer yourself, buy the 100 kg. It will last a lifetime. Or use the crushed concrete. The advantage is that you also enrich the soil in magnesium and iron.

@chornedsnorkack: You mean silicate recovery, as suggested first in the post? The calcium silicates formed during the firing of the bricks are impregnated with silica (that one) and other silicates (aluminum, magnesium, iron possibly, sodium perhaps), not to mention alumino silicates and whatnot.

Same problems again, mate.
Quote:

You can't separate them physically because the particles or whatever are very small, well mixed and in the solid state. They don't melt without decomposing and they're also insoluble. You can't separate them chemically without destroying them.

You may even recover (some of) the calcium by leaching the crushed bricks with acid (which, I suppose, produces the same unbearable smell as crushed concrete with acid). But you don't want to crush them. Unless you have a way to make the process dust-free and are using your PPE, you risk silicosis. Not much funnier than asbestosis, you see.

To long, didn't read: If you want calcium silicate, buy it. If you have a furnace, make it from sand and lime. If it is for farming, use the concrete as it is, the plants won't care.




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[*] posted on 13-3-2024 at 09:17


Quote: Originally posted by bnull  


@chornedsnorkack: You mean silicate recovery, as suggested first in the post? The calcium silicates formed during the firing of the bricks are impregnated with silica (that one) and other silicates (aluminum, magnesium, iron possibly, sodium perhaps), not to mention alumino silicates and whatnot.

Same problems again, mate.

I was referring to "silicate bricks". Apparently go by some other names like "sand-lime brick". A popular building material - available cheaply new made, and even cheaper/the recycling moment as building waste and demolition/repair waste.
In contrast to cement concrete (which intentionally includes alumosilicates) and ceramic bricks (intentionally of alumosilicate clay), silicate bricks exclude aluminum from both lime and sand.
The one likely impurity is excess sand.
Quote: Originally posted by bnull  

Quote:

You can't separate them physically because the particles or whatever are very small, well mixed and in the solid state. They don't melt without decomposing and they're also insoluble. You can't separate them chemically without destroying them.


To long, didn't read: If you want calcium silicate, buy it. If you have a furnace, make it from sand and lime.

A classic review:
https://nvlpubs.nist.gov/nistpubs/nbstechnologic/nbstechnolo...
Unlike ceramic bricks, silicate bricks cannot be made by kiln. They require autoclave.
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[*] posted on 13-3-2024 at 15:57


Quote: Originally posted by chornedsnorkack  

I was referring to "silicate bricks". Apparently go by some other names like "sand-lime brick". A popular building material - available cheaply new made, and even cheaper/the recycling moment as building waste and demolition/repair waste.
In contrast to cement concrete (which intentionally includes alumosilicates) and ceramic bricks (intentionally of alumosilicate clay), silicate bricks exclude aluminum from both lime and sand.
The one likely impurity is excess sand.

I know, they're also advertised as calcium-silicate bricks. Sand has not a fixed composition, it's mostly silica plus calcium carbonate and silicates, the proportions vary according to the geology of the area. The presence of aluminum in some is unavoidable; there is feldspar, for example. Or thorium, as in the monazite sands in India and Brazil.

Suppose you have a brick factory. Would you try to purifiy the sand before making the bricks? No, it costs money, you just clean it enough to remove organic material and some other things (free metals, for example), and on with it to the mixer. Maybe even add crushed flint or other silicate rock to it. The end product is basically the starting material (sand and silicates) with calcium silicate as binder and some calcium hydroxide (which becomes carbonate as the brick ages). Even so, you can't separate calcium silicate physically or chemically--without decomposing the silicate--from the rest.

Quote: Originally posted by chornedsnorkack  

Unlike ceramic bricks, silicate bricks cannot be made by kiln. They require autoclave.

I wrote, "If you want calcium silicate, buy it. If you have a furnace, make it [calcium silicate, not silicate bricks] from sand and lime." It was the suggestion offered by @Admagistr. That's why you needed a furnace, the reaction runs above 1400 °C.




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[*] posted on 14-3-2024 at 00:52


I needed Calcium Silicate for high quality small scale metal furnace insulation.
With starting from scratch

[Edited on 14-3-2024 by nikotyna1939]
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[*] posted on 14-3-2024 at 05:36


Why didn't you say it before? I thought you needed it for some reaction or for rice farming. The refractory properties never crossed my mind.

Did you search the forum? There are some threads about refractory compositions not necessarily based in calcium silicate.

There was also this guy. The last time his website was updated was in 2018, so I don't know what happened to him, if he's still melting and casting, or even breathing. Take a good look around.

Or you can buy the refractory cement, either local or from China (you're in Indonesia, right?). I know it's out of the 3R philosophy and you'd rather make your own composition, but it's an option. It saves time.




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[*] posted on 14-3-2024 at 06:47
Reacting calcium hydroxide and silica


At what temprerature will Calcium Hydroxide and Silica reacts to produce Calcium Silicate ?



[Edited on 14-3-2024 by nikotyna1939]
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[*] posted on 14-3-2024 at 07:47


Quote: Originally posted by nikotyna1939  
I don't just buy calcium silicate because in my area you need to buy calcium silicate in bulk quantity like 100 kg to get a reasonable price.

also i needed only about 10 kg only.


Are you searching for "calcium silicate" or are you searching for "wollastonite"? Most small-scale vendors will use the latter term. Probably due to a bias against "chemicals" among consumers. Eg:

https://customhydronutrients.com/Wollastonite-natural-calciu...




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[*] posted on 14-3-2024 at 08:52


Quote: Originally posted by nikotyna1939  
At what temprerature will Calcium Hydroxide and Silica reacts to produce Calcium Silicate ?

Well...
Quote: Originally posted by Admagistr  
Truly pure calcium silicate of solid composition can be obtained by fusing a stoichiometric mixture of SiO2 and CaCO3 (CaO) at high temperatures, just over 1400 C.

Both calcium carbonate and hydroxide decompose to CaO at about 1000 °C. You will need a furnace.

[Edited on 14-3-2024 by bnull]




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[*] posted on 14-3-2024 at 09:49


You can use a furnace like this, you can also buy a lower volume version which is cheaper:
https://uk.vevor.com/melting-furnace-c_11137/vevor-6kg-propa...
But, for the chemical reaction to proceed quickly, it is best to have a temperature about 100 C to 200 C higher than a little over 1400 C. Over 1500 C to 1600 C. For this, one could use a coke thermally isolated from the surroundings and an air stream obtained by a blower.
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[*] posted on 16-3-2024 at 07:39
using a blowtorch to produce calcium siilicate from calcium oxide and silica on a small scale?


would 1800 degree celsius blowtorch sufficient to make about 5-10 gram of calcium silicate from calcium oxide and silica on a small scale?
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[*] posted on 16-3-2024 at 08:12


Quote: Originally posted by nikotyna1939  
would 1800 degree celsius blowtorch sufficient to make about 5-10 gram of calcium silicate from calcium oxide and silica on a small scale?


Yes! This is the ideal temperature for a fast and smooth reaction. The temperature can be slightly higher, that's not a problem, it's a good insurance that the whole mixture will react. The problem would be if it was a few hundred degrees short of a successful reaction. And exactly what kind of burner do you have? Can you post a picture or a link;)? I don't have an 1800 C burner, I have an autogenous burner that can pull the temperature up to just over 3000 C, ideally.
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[*] posted on 17-3-2024 at 01:44


After reading this thread, it all boils down to one question.
Why?

You have a supply of something rock-like and inert which is an admixture of dozens of different minerals.
And you want to use a ton of expensive reagents to make something sand-like and inert and maybe pure but not really useful. And this product is literally dirt cheap to buy.

I am sure there is something I am not getting here.
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[*] posted on 17-3-2024 at 11:59


At least it is not like those pearls in Detritus, as "alcohol reduction by living fish gills", or "have you tried extracting amine from bodily fluids".



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[*] posted on 17-3-2024 at 22:48


The less said about them, the better.
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