Filters containing Gold

[LeftyTheBandit]

When you do you final filter of your gold, I find it difficult removing the gold in the filter that is left after removing the caked gold powder. I have numerous filters with large amounts of residue left. My plan for now is to incinerate once I get enough but I can't help but know there must be a better way.

Evaporating dish?
Wet-Ashing - Dissolving the filter chemically, I think?
Spray the filter after removing cake into a drying dish...

I see Steve with that nice package of gold going into the dish, but getting from the filtering to the nice package of dried gold into the dish is eluding me.

 

[oldtimmer]

First, do not filter the gold. Instead, it is easire and faster to decant the liquid from the gold and leave the gold in the bottom of the container. You can then do your rinsing in the same beaker. When you are done with the rinse, leave just enough water so that you can pour the gold into an evaporating dish to dry the gold. You will need to use a squart bottle to get the last of the gold into the dish. Let the gold settle to the bottom and gently pour off the excess water and gently warm the dish to dry the gold

As it is very difficult to incinerate where I live, and when I was in the same place that you are, I made a beaker of AP to disolve the gold from the filter paper. I make just enough AP so that when the filter is in the AP, it is deep enough to cover the filter where the gold is and not the entire filter.

Hope that this helps.

dave

 

[LeftyTheBandit]

Hmm. interesting, redissolve the gold back into solution and rinse the filters clean of solution, then drop it again with smb.
Too many concussions in my younger days, thank you.

Time to buy an evaporating dish.

 

[Oz]

I agree with oldtimmer that decanting is best. Once you have rinsed (what I am assuming is foils or sponge) a few times with distilled water you can spray the rest out of your beaker with a spray bottle of distilled water into an evaporating dish to dry it.

If it is material you “have” to filter, by all means use a spray bottle to scavenge your material out of the filter. still safe your filter for later processing by incineration though, just because you do not see it does not mean it is not there in quantities worth recovering.

As to wet washing…
Stay the heck away from the process until you have loads of experience and top flight equipment. It is hazardous!

 

[Harold_V]

First, do not filter the gold. Instead, it is easire and faster to decant the liquid from the gold and leave the gold in the bottom of the container. You can then do your rinsing in the same beaker. When you are done with the rinse, leave just enough water so that you can pour the gold into an evaporating dish to dry the gold. You will need to use a squart bottle to get the last of the gold into the dish. Let the gold settle to the bottom and gently pour off the excess water and gently warm the dish to dry the gold

I'll go you one better, and it is a tried and proven process. I used it for more than ten years, refining on a daily basis.

Leave the gold in the same vessel that was used for precipitation until it is ready to be weighed or melted. There is no need to transfer to an evaporating dish to dry the gold. All that does is add an unnecessary step that has no benefits.

Harold

 

[qst42know]

Leave the gold in the same vessel that was used for precipitation until it is ready to be weighed or melted. There is no need to transfer to an evaporating dish to dry the gold. All that does is add an unnecessary step that has no benefits.

Harold

That's assuming the work is being done in a beaker, coffee pot or similar heat resistant glass and not a plastic bucket or fruit jar. Many vessels will work but it will limit some process choices. I have cracked a couple jars, one I was trying to warm gently, the other from the heat of the reaction itself. No more jars for me.

 

[4metals]

If you have a good vacuum system you can filter the gold through an ashless filter paper in a buchner funnel. Then you scoop off all of the gold you can easily get and place it in the crucible for melting. Roll up the paper and place it on top of the gold in the crucible. The paper will burn off completely as long as it is exposed to air and any gold trapped in the paper will be in the melt. Before you pour out the gold, add a pinch of borax followed by a pinch of niter which will completely burn off any residue leaving nothing but melted fine gold in the crucible for you to pour out.
It is important that you don't bury the paper under the gold, it seems a bit odd but I have seen gold poured out of a crucible only to have unburned paper fall out of the crucible unburnt, while all of the gold has melted around it. Even at elevated temperatures if there is no air the paper will not burn. If it stays on top it burns completely.

 

[Harold_V]

That's assuming the work is being done in a beaker, coffee pot or similar heat resistant glass and not a plastic bucket or fruit jar.

Yes, that's correct, and I stand corrected!
I used NOTHING but lab ware for processing gold, so, for me, there was never an issue with objects that would melt, or perhaps crack when heated.

I am adamant about NOT using plastic for precipitation. The only word I can think of for its use is stupid. Preciptated gold sticks tenaciously to plastic----so why encourage problems? YMMV, or course. :lol:

Harold

 

[lazersteve]

I'm with Harold on this one.

Once the gold is precipitated it should never leave the beaker. The only exception I can think of is when I combine two precipitations before the HCl wash process. In this case I rinse the gold powder into the second beaker and continue.

In my AP video I demonstrate transferring gold foils from the reaction bucket to a filter for purposes of a final rinse. The real secrets behind getting the gold out of these filters is one of two solutions for me:

1. Let the filter dry and peel the gold off of the filter as one mat or blob. If any sticks fold the outside edges of the filter inward (like a taco) and gently rub the two folds together while tipping the filter upright to push the gold towards the center of the fold. This forms a sort of spout that allows you to easily work the gold into the new container.

2. If you are in a hurry use the spray bottle to chase the foils and fine gold powder into the new container. After the gold is transferred let it settle and pour of the excess liquid. Proceed to dissolving the foils.

Even after using either of these two methods for foils, I still save the filter in my filter bag for incineration later.

Steve

 

[Lou]

If your gold is pure and the precipitation method correct, it will form a nice precipitate that will easily separate from quality filter paper, even when wet.

The other option is a fritted filtration plate--the gold does not stick to this very well, and any milligram traces of gold lost can eventually be collected by boiling the frit in aqua regia. This is only done when one notices the filtration speed of the frit decreasing as the gold collects on it.

 

[mike.fortin]

Lou. what size pore is frit hole. thanks.mike.