# AP leaching tank with integrated filtration and rinsing



## siddharta (Dec 30, 2012)

Hi,

I was doing some thinking and I came up with an idea to build large AP tank for about 50 kilos of fingers.

Main idea is:

when done leaching, you pour out acid to a container. First mesh stops bigger foils, second one stops everything that passes through first one. In separation tank foils sink to the bottom.
Then you close valves and pour about 30 liters of tap water. Rinse fingers with that water to get main of remaining acid off. Open valves and pour into second container.
then you turn on sprayers and connect waste water hose to the outlet. In this stage, I believe it is safe to connect waste water hose to a sewage network, since there is almost no acid left on the fingers.
Now you can manually rinse all of the fingers and water keeps flowing out to a sewage. So no more filter papers, no more bunch of buckets, water sprayers...
When done rinsing, you just open separation tank, pour out the water and collect material.

What do you guys think of this concept? Is it worth to build a prototype?
Every comment is welcome.

Boris

Here is some scheme:


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## butcher (Dec 30, 2012)

Boris,
I cannot see pictures here, but I would not tie anything to a sewer system, not only could some value go down the sewer if something did not work right, but you could put toxic materials into other peoples drinking water.


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## siddharta (Dec 30, 2012)

Here is the image (or it should be):

http://imageshack.us/photo/my-images/26/leachingdevice.jpg/

Well you can hook up to a waste water storage container also. 

The main idea is to make rinsing fingers and collecting the foils easier...


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## NobleMetalWorks (Dec 31, 2012)

I did a post on the 110 gallon tank I am using for AP...

I used my experience in salt water reef tanks. It's pretty simple. You use a pump rated for acid. I have a 110 gallon main tank and a 30 gallon sump. The pump, pumps the AP solution from the sump into the tank throw 4 nozzles that are placed inside the tank. Boards hang from a bar that runs the length of the tank, I used plastic curtain hangers/rings with poly string to plastic clamps. The clamps never are submerged into the solution. The four nozzles (PVC pipe that was heated and smashed to make a flat directional nozzle) are placed right before the boards come out of the tank, and about middle. The reason I did it this way is so that the AP can start to eat the copper before they are slid down the bar at the first agitation station (nozzles). As soon as I slide the boards into that area, the gold starts foiling off. I have long bubblers under the boards so that as I am bubbling oxygen to keep the copper chloride oxygenated, the bubbles also agitate the gold foil. As the boards are moved down, the last station in the tank whatever foil is left, comes off. Then the board is sprayed down, and retained to be recycled. I use what is called a gravity filter. As water is pumped into the tank, a pre filter box that hangs on the side, catches gold foil in a polypropylene sponge. The solution is actually pulled into the pre-filter by the negative pressure caused by the solution running down the pipes to the sump. All the large gold foil is captured in the pre-filter. Then I have several poly felt filters that capture the smaller material in the sump filter. The filtered solution is then pumped back into the tank through the agitation nozzles and the entire process starts over. If the power runs out, the gravity filter will only pull about 10 gallons of solution out of the tank, which the sump can more than handle so there is no issues with loosing power.

This set up has been working out really well for me, I couldn't be happier with the results. A board generally takes about 12-24 hours to completely strip, some boards have stripped in about 4 hours. The agitation works really well.

Scott


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## siddharta (Jan 1, 2013)

Scott I remember reading your post. Do you have any pictures of your setup? 

BTW, Happy new year to all.

B.


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