Sciencemadness Discussion Board

Make Calcium carbonate from calcite

Housane - 27-11-2018 at 22:56

Hi All

I have some Calcite and I wanted to purify calcium carbonate from it. What would you suggest is the best way to do this.

Thanks

Housane

Foeskes - 28-11-2018 at 02:52

Well if it's clear or white, then I'd say it's pretty pure especially if it's in the form of large crystals.

Housane - 28-11-2018 at 10:19

Hi how can I then make it into a powdered form to make calcium hydroxide what would you subject is best. The chunks are rather large

fusso - 28-11-2018 at 12:02

Just heat it up to 8xxC to form CaO. The pressure from released CO2 will break the chunks apart.

Ubya - 28-11-2018 at 12:08

Quote: Originally posted by fusso  
Just heat it up to 8xxC to form CaO. The pressure from released CO2 will break the chunks apart.

then add water and a slurry of calcium hydroxide will form (be careful of the exothermic reaction)

Housane - 1-12-2018 at 13:44

Hi Ubya how did you get the part at the bottom

fusso - 1-12-2018 at 14:47

Quote: Originally posted by Housane  
Hi Ubya how did you get the part at the bottom
Filtering.

MrHomeScientist - 3-12-2018 at 14:09

Well calcite is already calcium carbonate, so smash it with a hammer and you're done!

If you want to ensure purity, probably the easiest way would be:
1) Crush the rock as much as you can with a hammer / mortar & pestle.
2) Dissolve the rock in vinegar. May take a few hours or days; wait until the bubbling stops, then add a bit more vinegar and make sure bubbling doesn't start up again.
3) Filter off any undissolved rock. The solution contains calcium acetate.
4) Add baking soda to the solution. This precipitates the calcium back out as carbonate.
4a) It might be better to first dissolve the baking soda in its own solution, then add that to the acetate solution. This way you know the precipitation is done if you add baking soda solution and no more is observed.