Sodium BoroHydride
- Thread starter Froggy
- Start date
Help Support Gold Refining Forum:
loco
Well-known member
http://store.hvchemical.com/search.htm?searchterm=sodium+borohydride&searchmode=all&s_category=0&oper=lt&searchprice=&DoSearch=Show+Matches&numresults=10&viewfrom=1&step=2
http://www.sciencelab.com/page/S/PVAR/SLH1762
http://www.sciencelab.com/page/S/PVAR/SLS4615
here are a couple places I found from a quick googling. sciencelab seems to have a nice selection. I, like yourself, am not sure how thier prices stack up.
http://www.sciencelab.com/page/S/PVAR/SLH1762
http://www.sciencelab.com/page/S/PVAR/SLS4615
here are a couple places I found from a quick googling. sciencelab seems to have a nice selection. I, like yourself, am not sure how thier prices stack up.
That hydrazine solution is not what you are after--it's a standard, meaning it's mainly water.
The prices on borohydride are decent, best I've seen is about 2/3 of that from another source.
Personally, I suggest you make your own hydrazine for cheap!
This is how you do it:
http://www.sciencemadness.org/talk/viewthread.php?tid=757&page=1#pid6539
It shouldn't cost more than 5 bucks a pound if you're doing it right. That gives you hydrazine sulfate, which is effective and much safer. You can make the freebase hydrazine (not recommended!!) by distilling the sulfate salt with KOH, then fractionally distilling it again to separate the hydrate from the hydrazine. That's how I think it's done, don't quote me, but if you want to do that too tell me so I can double check my memory out of the book!
The prices on borohydride are decent, best I've seen is about 2/3 of that from another source.
Personally, I suggest you make your own hydrazine for cheap!
This is how you do it:
http://www.sciencemadness.org/talk/viewthread.php?tid=757&page=1#pid6539
It shouldn't cost more than 5 bucks a pound if you're doing it right. That gives you hydrazine sulfate, which is effective and much safer. You can make the freebase hydrazine (not recommended!!) by distilling the sulfate salt with KOH, then fractionally distilling it again to separate the hydrate from the hydrazine. That's how I think it's done, don't quote me, but if you want to do that too tell me so I can double check my memory out of the book!
I once worked for a refiner that used full strength liquid hydrazine to drop gold from aqua regia. It only took a small amount and it reacted violently and generated a lot of heat. It seemed like someone was always getting acid burns. I vowed to never use it.
Hydrazine sulfate is another story - no violent reaction. Although it's somewhat carcinogenic (especially the dust), I used it often for dropping gold out of aqua regia that contained large amounts of nitric acid. Nitric acid doesn't affect the precipitation. You don't have to boil the AR, add urea, or treat it in any other way. When you buy it, a slight amount of water has been added to prevent dusting. I used to break up the clumps by grinding it with the bottom of a small beaker. I then sprinkled the powder into the aqua regia, in small increments, and gave the solution a stir. It doesn't take much. Use gloves, a mask, and a fume hood.
Hydrazine sulfate is also used, by some of the large refiners, to selectively drop PGMs. The precipitations are pH dependent. Check the patents.
Hydrazine sulfate is another story - no violent reaction. Although it's somewhat carcinogenic (especially the dust), I used it often for dropping gold out of aqua regia that contained large amounts of nitric acid. Nitric acid doesn't affect the precipitation. You don't have to boil the AR, add urea, or treat it in any other way. When you buy it, a slight amount of water has been added to prevent dusting. I used to break up the clumps by grinding it with the bottom of a small beaker. I then sprinkled the powder into the aqua regia, in small increments, and gave the solution a stir. It doesn't take much. Use gloves, a mask, and a fume hood.
Hydrazine sulfate is also used, by some of the large refiners, to selectively drop PGMs. The precipitations are pH dependent. Check the patents.
Say Lou, after reading how to make hydrazine sulfate,........wow......... perhaps we can get you to do it.....and sell us some....
Yea?
Randy
Yea?
Randy
A
Anonymous
Guest
Unless you have a real good lab with a real glass still setup with nitrogen purge don't even try making free hydrazine! The sulfate salt works just as well for precipitation of pm's
Ahah, but I do have a real good lab with argon purge. I'm well familiar with hydrazine.
I do have a 55L reaction flask that would be perfect for this synthesis and would be willing to do ''commission'' reactions. I can say from personal use that hydrazine is an excellent, clean reducing agent--it goes to nitrogen gas, and you're left with ammonium sulfate, easily rinsed out. It also drops the metal out as a heavy sponge, not a fine powder like borohydride does.
If there is enough interest, I can begin work this weekend on making you all hydrazine. It would have to be a minimum of 2 kilograms of the sulfate stuff.
By the way, as a general rule, I ALWAYS keep hydrazine away from oxidizing agents, so if you do use even the pretty tame (and least carcinogenic of the common hydrazinium) sulfate, make absolutely certain that you have diluted your aqua regia sufficiently!
NEVER add hydrazine sulfate (and especially) free hydrazine to a concentrated solution still containing nitric acid!
Louis
I do have a 55L reaction flask that would be perfect for this synthesis and would be willing to do ''commission'' reactions. I can say from personal use that hydrazine is an excellent, clean reducing agent--it goes to nitrogen gas, and you're left with ammonium sulfate, easily rinsed out. It also drops the metal out as a heavy sponge, not a fine powder like borohydride does.
If there is enough interest, I can begin work this weekend on making you all hydrazine. It would have to be a minimum of 2 kilograms of the sulfate stuff.
By the way, as a general rule, I ALWAYS keep hydrazine away from oxidizing agents, so if you do use even the pretty tame (and least carcinogenic of the common hydrazinium) sulfate, make absolutely certain that you have diluted your aqua regia sufficiently!
NEVER add hydrazine sulfate (and especially) free hydrazine to a concentrated solution still containing nitric acid!
Louis
Irons
Well-known member
I checked and it appears Hydrazine Sulfate may require a hazmat tag for shipment.
Be aware of any extra cost involved. Bummer.
On edit:
It seems that in small quantities, it might not. Does anyone know what the cutoff weight is?
Be aware of any extra cost involved. Bummer.
On edit:
It seems that in small quantities, it might not. Does anyone know what the cutoff weight is?
ORM-D for this stuff is usually 1 pound. It's often cheaper for me to send several 1 pound containers rather than spend 30 dollars on hazmat fee.
I once sold sodium so that's how I did it. No more than 30g of Na is allowed ORM-D
For those of you with deep pockets, I suggest DHL--never had a bad hazmat shipping experience with them.
I once sold sodium so that's how I did it. No more than 30g of Na is allowed ORM-D
For those of you with deep pockets, I suggest DHL--never had a bad hazmat shipping experience with them.
I dropped gold using hydrazine sulfate. No dilution. Zero problems. The gold dropped stoichemetrically. Great stuff.
That seems really odd.
Why are you using aqua regia with such a high concentration of nitric acid?
I can believe maybe 20% concentration is nitric acid at the upper end, but not 50%?!
Why are you using aqua regia with such a high concentration of nitric acid?
I can believe maybe 20% concentration is nitric acid at the upper end, but not 50%?!
I used it to dissolve gold braze from 410 SS.
Ah, ok then.
I just know from personal experience that hydrazine and its salts don't like concentrated HNO3. Perhaps 50% is a safe concentration, but I know for certain that over 90% by mass HNO3 and you are asking for an explosion.
I just know from personal experience that hydrazine and its salts don't like concentrated HNO3. Perhaps 50% is a safe concentration, but I know for certain that over 90% by mass HNO3 and you are asking for an explosion.
