[covek11]

I tried to precipitate CoCO3 from Co(NO3)2 and NaHCO3. When I do that at room temperature, I obtain Cobalt Hydroxycarbonate.
When I heat up solution of NaHCO3, I end up with pure CoCO3 with much larger particle size. Does anyone have idea how to make pure CoCO3 at room temp. ?

[BluRay]

I tried to precipitate CoCO3 from Co(NO3)2 and NaHCO3. When I do that at room temperature, I obtain Cobalt Hydroxycarbonate.
When I heat up solution of NaHCO3, I end up with pure CoCO3 with much larger particle size. Does anyone have idea how to make pure CoCO3 at room temp. ?

If you want to get the carbonate why did you use an hydrogencarbonate? Use the sodium carbonate...

[covek11]

I tried Na2CO3, bu that gave Cobalt Hydroxycarbonate too. That is because the solution of Na2CO3 is alcaline, with  pH = 12. Carbonate ions hydolize giving OH- ions which react with free Co++ ions.
I wonder how they make CoCO3 or NiCO3 on a large scale ?

[BluRay]

I tried Na2CO3, bu that gave Cobalt Hydroxycarbonate too. That is because the solution of Na2CO3 is alcaline, with  pH = 12. Carbonate ions hydolize giving OH- ions which react with free Co++ ions.
I wonder how they make CoCO3 or NiCO3 on a large scale ?

Maybe they use another solvent instead of water. Try with ethanol, or acetone. You should also find a carbonate soluble in that solvent, don't know if sodium carbonate is  (potassium or lithium carbonate?).

[AWK]

see
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy
Volume 60, Issue 12, October 2004, Pages 2803-2805
A novel method for preparation of cobalt(II) and lead(II) carbonates
M.S. Refat,  S.M. Teleb and S.A. Sadeek

CoCO₃^.4H₂O

[BluRay]

Also, you could try saturating with CO₂ a dilute solution of HCO₃^- so that the pH is very low.

[covek11]

Thank you for your replies.
Unfortunately I don't have approach to Spectrochimica Acta. Could you please tell me, just in a few words, what they used ?
BluRay, usage of CO2 wouldn't be cost effective. Can you imagine how much CO2 I would need to pump into solution in order to make 10 kgs of CoCO3. There has to be an easier way.

[Arkcon]

I've tried to search for a free link to a procedure for making metal carbonates, that you can't make the usual way.  I've found this one, which should provide the abstract to you for free when you click it.

http://www.springerlink.com/content/t66352u3t764p36p/

It doesn't mention your choices of metals specifically, but it does specify a method you can try.  It is, coincidentally, the same method specified in AWK:'s link.  Oh, and one of the author's is the same in both papers, so yeah, same idea.

[covek11]

I've tried to use urea in approximatelly the same scale as those authors have done.
100 ml, heat up for 2-4 hrs !!!!
It is all right for small laboratory experiment and only for that.

[Arkcon]

Then, as an alternative method, make CoCO3 with heated NaHCO3, and then grind the larger particle size you get, down to the size you need.  Either you are making small particles for some nanotech research like the authors of the cited papers likely are, and their methods are likely adequate or you're making bulk chemicals for the ceramics glazing market.  In which case, buy some rock, and start grinding.   Or be more specific, what do you need, in terms of quantity and quality, for your application, which is ... what, exactly?

[covek11]

I would like to make a moderate size batch 5-10kgs. So, it isn't large scale or lab size batch. Something in between. So far I was able to make pure CoCO3 with particle size around 10 microns only in cases when solution of NaHCO3 was heated up, but I don't think particle size is regulated by T. My opinion is that particle size is regulated by pH. I've heard some people used a room T solution of combined Na2CO3 and NaHCO3 and they obtained coarse CoCO3 (~10 mic). What would be possible reason for that ?
When I did any precipitation at room T with either Na2CO3 or NaHCO3 (separate precipitations) I ended up with 1 mic and below particle size.

[BluRay]

BluRay, usage of CO2 wouldn't be cost effective. Can you imagine how much CO2 I would need to pump into solution in order to make 10 kgs of CoCO3.

I don't understand here. Of corse you would use a container under pressure, well closed (something better than a champagne bottle, of course ), so you would only use the amount of CO2 that is required for the reaction. You are not telling me that CO2 is more expensive than Cobalt nitrate?

[covek11]

Unfortunately all I have is open head plastic tanks.

[BluRay]

Unfortunately all I have is open head plastic tanks.

And with all that instrumentation you want to get kilos of cobalt carbonate?

[covek11]

Pardon, I meant all I have...when it comes to reaction vessels.
When it comes to everything else(metering pumps, drivers connected to pH controllers, variable stirrers, heaters....) I've got it.