# Best way to filter gold powder?



## masonwebb (Sep 3, 2013)

I have been noticing that after I cement the gold, the powder is sometimes too fine for coffee filters. So I have powder at the bottom of a beaker with about 1L of spent solution on top of it. What do you guys think is the best way to go from this to having dried powder?


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## Harold_V (Sep 3, 2013)

I can't think of _*even one reason *_why you have to filter. Maybe you can enlighten me.

Have you read Hoke's book? 

Do you understand Hoke's book? 

Do you really think you have need to filter this material? 

Do you understand the concept of washing the recovered gold?

Share your thoughts with us. Maybe we can learn something. 

Harold


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## butcher (Sep 3, 2013)

I rarely filter powders or precipitants, although I often filter the solutions above them.
Decanting (or siphoning) is a great tool; the powders can be pre-washed in the same vessel and settled and decanted again, or dissolved and precipitated again...

After settling well, I will siphon off the liquid with the tool shown below, removing liquid close to the powders, but leaving enough liquid that I do not disturb the settled powder, then tilt the vessel slightly, and carefully as not to disturb the powders, but to get the liquid pooled to a higher level above the powders on one side of the vessel, and get the last few inches and drops of liquid from above the powders with the pipette.

If rinsing or diluting, let the powders settle well again before decanting the solution (or siphon again).

The less you transfer powders or material from vessel to vessel the less you will take chances of lose, many times most of a process or even several processes can be done without transferring the values, doing most of the procedures in a one pot reaction.


Sometimes filtering or transferring is necessary. a water wash bottle or spray bottle comes in handy here.

Filters often can let fine unwanted material pass through a filter, or it can also trap values in the filter, sometime filtering is just a necessity, for this reason save those filters that do contain value. 

After refining twice and pre-washing the powders I will normally transfer the gold powders to a small beaker (usually 50ml) using a wash bottle, this small beaker is used to do the gold washes as suggested by Harold in the thread getting your gold pure and shiny in the help needed section, (decanting with the pipette as described above is how I remove the wash solutions), I use the small beaker for washing and rinsing and drying in, I use a small electric hot plate (coffee mug warmer) to slowly dry the powders, with a small watch glass cover to keep dust and dirt out during washing, A piece of paper towel serves as a cover in the drying process, keeping a watch on the drying process, just before the powders are completely dry, I will pick up the beaker and bang its bottom against the heel of my free hand, when the powders are almost, but not completely dry this will knock the powders together in one lump, continuing this as the powders dry you can form balls of gold powders from the lump, these balls rolling around in the beaker will also collect other loose powder of gold into these brown balls, helping to collect the gold together, cleaning the small beaker of gold powder that would otherwise stick to the glass, after dried these balls of gold are also easier to transfer to a melting Dish, and are easier to melt, less likely to blow gold out of the dish with the torch, than which can happen when trying to melt the fine loose gold powders.


I will also use separate tools to siphon the liquids (clean designated tools for the final procedures) so as not to add contaminate to the final washing procedures.

In your reading of Hokes you will get a better understanding , and reading Harold's posts, you can learn many of the tricks of the trade and more.

Edit to correct spelling of the word siphon.
Thanks Dave for helping me out with my spelling problem.
(note: the filtering of the solution should have been done before the gold was precipitated).


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## Lou (Sep 3, 2013)

Decanting is a man's best friend.


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## Geo (Sep 3, 2013)

never filter gold powder. its a good way to trap values that will need to be processed later. gold is 19.3 times heavier than water and metallic gold will settle completely out of solution given enough time. removing the liquid from gold powder from the top down is always the best procedure.


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## ilikesilver (Sep 3, 2013)

masonwebb said:


> I have been noticing that after I cement the gold, the powder is sometimes too fine for coffee filters. So I have powder at the bottom of a beaker with about 1L of spent solution on top of it. What do you guys think is the best way to go from this to having dried powder?



I suggest whole hardedly that you listen to these pro's. I have been on this forum for a year now, and have learned to not filter as much as possible, if you do especially using coffee filters you will loose gold or make your process a lot longer than needed. read up, study up, and listen to them, i have, and still will.


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## glondor (Sep 4, 2013)

Use the tools and methods described, no filtering is necessary. To help settle fine dirty gold powder, I find if I heat for a half hour or so, to just below boiling, then let it cool, all the powder will be on the bottom of the vessel. Works every time.


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## Aog (Sep 5, 2013)

Hello all. I agree 100% with settleing and decanting. Its by far the simplest meathod but not always the quickest. However if time is not on your side, this may help. Instead of waiting for settlement. 

I use a buchner funnel and whatman filter papers grade 542
There acid resistant and will catch all of your fine gold. (Warm acid is more likley to fail your filter paper)
There also ashless.

I chuck the filter paper in to dry with the fine gold recovered and melt together. 

http://www.whatman.com/QuantitativeFilterPapersHardenedAshlessGrades.aspx

Not the fastest flow rate on the filtration side but it frees me up for other jobs. But in my opinion the best for the job, should it ever need filtering.


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## butcher (Sep 5, 2013)

I do not see any benefit to filtering gold that has been precipitated from solution, the filtering should have been done while the gold was still in solution before precipitation was done.

Decanting the solution after testing to verify all gold was precipitated, and then redissolving the gold powder for a second refining, and then filtering the gold chloride solution I could understand.

Working with small volumes or lots of gold, as we all know there are always small losses (or amounts of gold temporarily misplaced, as in filters stock pot and other areas), so anywhere you can eliminate the loss of value we should try to adjust our procedures to help prevent loss. working with large lots a small loss may not amount to much, but when working with many small batches, lots of small losses of value can add up quickly to larger volumes of gold lost.

Anywhere you can prevent these losses is more gold in the melting dish at the end of the processes, the less you transfer the gold from vessel to vessel, or in this case filter when unnecessary, the more gold you will have in the end.


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## masonwebb (Sep 24, 2013)

Thank you everyone for your tips! I have now taken to decanting quite well, like most of the things involved in gold recovery some practice was needed.
I will use a shallow dish next time for when I evaporate the remaining water off, I find the powder tends to get stuck to the bottom. I used a folded up business card to scrap the powder from
the bottom. I have been saving my filters for process when I get a decent amount. 

Thanks!


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## Geo (Sep 24, 2013)

too, i find that a narrow column or graduated cylinder makes for some easy decanting. the smaller diameter lets you pour off more solution without disturbing the powders.


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## butcher (Sep 24, 2013)

After refining I transfer the powders to a small 50ml clean beaker, used for the process of washing and drying the gold powders, a small electric burner coffee mug warmer works well to dry the gold, I like its mild temperature.

Using Harold's gold wash procedure, found in the help section under getting your gold pure and shiny.

The drying technique I use is posted here, when the process is done I have balls of gold easily transferred to a melting dish, and can be melted easier than powders, the balls of gold will not blow out of the dish as easily as powders will.

http://goldrefiningforum.com/~goldrefi/phpBB3/viewtopic.php?f=49&t=12215

Some more from Laser Steve:

http://goldrefiningforum.com/phpBB3/viewtopic.php?f=49&t=6861&p=61491#p61491
http://www.goldrefiningforum.com/phpBB3/viewtopic.php?f=52&t=1900&p=16039#p16039


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