HVAC filters incineration? Or?

Hello all,
I have a question for the experienced on this process. I own a jewelry store, and upon changing the filters on the roof top, I decided to keep them to see what material gets caught up in these from my shop. I do a fair amount of my own production of gold and silver product so I figured surely something has to get sucked up in these.
That said, I got a large Tupperware tote, and carefully dissected the filter membrane from the wire mesh, etc. I gathered up a softball size wad of dust, and did a test run on the material. First I incinerated, did the AR on it, the stannous showed positive for AU, dropped it with SMB, and see below pic, it produced the brown powder goal.

Now to my question. I have eight of these filters, 20x25x2 inches. Does anyone have a suggestion for incinerating these filters, or another process that may be easier to do to get the dust content out of them? I thought about possibly cutting them up into two inch squares and washing the filters in a large five gallon bucket and allowing the material to settle and decant off, or boil it down, etc. I am just not sure. Any help would be greatly appreciated on this matter.

Thank you for any and all feedback!

This looks like a fun refining project. I would recommend looking into refining carpets from jewelers, and specific posts by Harold.
http://goldrefiningforum.com/phpBB3/search.php?keywords=carpet&terms=all&author=Harold_V&sc=1&sf=all&sr=posts&sk=t&sd=d&st=0&ch=300&t=0&submit=Search

I guess that the wire mesh is made of steel? I would cut it down in smaller pieces, incinerate and then remove the mesh afterwards. I have no experience of refining filters though but I would love to get a job like this.

I just wonder how much gold there is in the ducting...

Göran

To process this material it does need incinerating but done carefully preferably with some sort of lid over the material and heated slowly from below, I used to use metal tote trays with a lid on and put them into a burnout kiln for lost wax casting and let them reach maximum temperature and keep it there for several hours.
Once you have your powder sieve it and crush any large pieces and place in a large or several large beakers depending on quantity, cover fully with Hcl and heat and add slow increments of nitric, to get full extraction of the gold will need agatation so actually boiling the AR is not a bad idea but be on hand and stir regularly to avoid hotspots and broken beakers, place a watch glass over the beakers while it isn’t been stirred.
If done right you should get around 90% of the gold onthe first try so if you recover 100 grams then you have 10 grams left or thereabouts so it’s whether it’s worth your time chasing the remaining values but bear in mind those figures are only right if you got the first extraction right.
As to the ducting if it’s fixed and rigid maybe use a flexible chimney brush with a bag sealed over the end if it’s flexihose disconect carefully and either brush or vacuum clean, I’m guessing you have polishing extractors so whatever makes it away from them will be very fine dust so it could well have fully coated your ducting.

Use a drum. In the drum put a metal 5 gallon can with the filters in it. use a heating element out of a oven. It's going to stink unless you divert the exhaust from the smoldering to a flame. The goal though is to burn first without oxygen, then vent oxygen in to roast the ashes.


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g_axe, nickvc, and snoman,
Thank you all for the excellent feedback! Seems that I need to find a good metal container with a good lid to get this project going. I will post my progress as this goes along.
Very sincere appreciation again!
Nauticamark

Nauticamark said:

I will post my progress as this goes along.

Click to expand...

I'm looking forward to it, too many threads are just a problem and a number of suggestions but we never get to know how it ended.

Good luck and don't be a stranger. 8)

Göran

I agree with Göran the successes are always good to hear about and better to see.