Bad Drop

[Moo]

I dropped my solution of auric chloride a couple of hours ago, I was expecting about 5-6 grams so I added 5 grams SMB I dissolved in pure water It did not clear straight away after a while I added a touch more in powder form, and has taken over the last 2 hours until now to clear and is just starting to slowly darken I tested with stannous and it stills shows a very strong purple colour, just as strongly as it did before the addition of SMB. What do I do?

 

[vyper]

I would say it sounds like you may have had some free nitric left in solution when you added the first 5 grams of SMB. Let it settle overnight and see what precipitates then check your solution with stannous for more values. Did you do anything to remove left over nitric? Did you double the volume of Auric chloride with distilled water first?

 

[Moo]

I used HCL/Bleach, perhaps free chlorine still there
thanks will leave overnight.

 

[philddreamer]

I little heat sometimes helps to precipitate the gold after adding the SMB.
Phil

 

[Moo]

Been sitting in the hot sun all day, how much heat do I need?

 

[Geo]

bring it to a slow boil for 20-30 minutes.

 

[Moo]

Thanks for the input people is leaving it overnight and then adding more SMB an option if it hasnt dropped? Boiling my gold scares me.

 

[nickvc]

The guys are giving you the best advice, put your solution on the hot plate and heat slowly, this drives off the chlorine and should allow your gold to drop, please do this either under a fume hood or outside and don't be downwind! You can just keep adding SMB but it's a waste of chemicals when the cure is easy, don't forget to test your solution with stannous when you complete the precipitation.

Edited for grammar.

 

[Moo]

I will boil Im assuming when any remaining chlorine is gone i will visually see the solution lighten again?

 

[ericrm]

I will boil Im assuming when any remaining chlorine is gone i will visually see the solution lighten again?

... not boil ... never ... harold would be mad lol ... boiling will create tiny buble that will fly out of your beaker and make you loose value... what your looking for is evaporating the dissolve chlorine in solution... heat your solution until you see fume and lock the heat at that point for a while , your do not want buble :lol:

 

[Geo]

Harold's peeve about the word boil is when people use the word boil when they mean evaporate.its ok to boil and as a matter of fact, if you read through some of Harold's post, he says there are time when you have to boil (like when you are washing and rinsing).you need to cover you solution when you have to boil. i had a problem with boiling when i first started do this but i am more confident now. as long as you do it correctly, you should have no problem boiling.