substitute for hidrazine

for many years i used hydrazine 25 to35% to precipitate pms from ar solutions----
suddenly hidrazine(here in brazil) is not alowed without a license(permission from the army)--is there a substitute that could be used instead of hydrated hydrazine? it was very efficient -----i am not having success in using formic acid as a reducing agent--
thanks for any help----
Arthur

hydroxylamine hydrochloride

thanks Lino for the information

By PM's do you mean precious metals or platinum group metals (PGM's)? Are you talking about reducing the salts or dropping pure metals straight from the acid? Please give a little more detail and I'm sure we can help you.

4metals, by pms i meant gold ,pd and sometimes pt----i used to make ar and then instead of using smb to drop gold(pms), i used hydrazine in the ar solution. With this procedure all the precious metals in the ar precipitated----then i used ar to repurify this precious metal for a second time and smb,for gold----i obtained a very high quality of gold
with hidrazine ,it took less then 10minutes to drop(precipitate)all the pms---and no pms was left in the ar solution(stanous chloride test)
without hydrazine for my first precipitate, i feel orphan,and i am looking for a good substitute
thanks
Arthur

Copper would be a suitable substitute and it's much cheaper. A bar of copper metal suspended in the solution while it is either aerated or mixed with a mixer will displace all of the PM's you are looking for. It is not as fast as hydraziine but it will work as effectively. Just make sure there is good mixing as the copper needs to be in contact with all of the solution, or should I say in contact with all of the dissolved precious metals. The stannous chloride test will still work as well.

You should also be doing this with all of your waste acids to collect that last little bit of precious metals you may have missed.

thanks again 4metals----Arthur

Dear Arthur:

There are many reducers for PM but you have to choose the ones that works for you.

About hydrazine you can make by your own mixing urea,sodium hydroxide and sodium hypochlorite but you will need some cristallization techniques.All these raw materials are available everywhere.

If you can,try to change hydrazine because is dangerous and toxic,look,I have used ascorbic acid to reduce silver solutions with great results,it works to reduce Pd in basic solutions.

Ascorbic acid ( Vitamin C) is expensive but it worths it,here in Mexico 1 kg costs $ 560 pesos ($ 43 USD).

I post for you a patent about ascorbic acid as reducer.Also,I have written an e mail to you,please,read it.

I hope it helps.

Kindest regrads.

Deus te abençoe.

Manuel