Making an underflow trap - first attempt

[Aggro]

Hi all

Just thought I'd share some pics of my latest little project. No idea if it's going to work or not, but hey, figured I'd have a go using up some scrap I had laying around the factory.
Polycarbonate sides, recycled plastic sheeting for the deck, PVC pipe and a sheet of aluminium for the trap.
Just need to put some sealant in the joints and I'll use clamps for the aluminium baffle so I can keep it adjustable for now.
I'll be giving it a test run tomorrow night with some material I have with lead in it. Finger crossed.

If it works, I might add an inline classifier to save sieving material down at the creek.

 

[Jemba]

I like your thinking cool, one question how hard will the drop's be to clean out? It will be interesting to get your view on the system well done. cheers

 

[AtomRat]

Interesting design mate! Never seen it done with that much of a circle lol it will be very interesting to see how it does work mate, and if it can life the blacks out. I made a test a couple of years back but using the U channel. Being able to fix not only the height, but also angle of the baffle will make testing easier, as holding onto it by hand was a bit wabbly. ( drilling angle and height adhust holes would have worked ) The U channel did successfully hold gold not problem but actively moving the baffle about was needed at times. Im pretty sure zero gold escaped, was mostly just fine dusty gold in the test. I found that it would have been better if i built more of a jig or frame to hold the sluice better under my tap and hold angle so i could study it properly

Good luck

 

[Aggro]

I like your thinking cool, one question how hard will the drop's be to clean out? It will be interesting to get your view on the system well done. cheers

Not sure on cleaning out yet Jemba, I'm thinking tipping it on it's side and flushing water in to it so it drains out the low side in to a bucket for now. Time will tell if it even catches lead first though, let alone gold. HA HA

 

[Aggro]

Interesting design mate! Never seen it done with that much of a circle lol it will be very interesting to see how it does work mate, and if it can life the blacks out. I made a test a couple of years back but using the U channel. Being able to fix not only the height, but also angle of the baffle will make testing easier, as holding onto it by hand was a bit wabbly. ( drilling angle and height adhust holes would have worked ) The U channel did successfully hold gold not problem but actively moving the baffle about was needed at times. Im pretty sure zero gold escaped, was mostly just fine dusty gold in the test. I found that it would have been better if i built more of a jig or frame to hold the sluice better under my tap and hold angle so i could study it properly

Good luck

Cheers AtomRat, I'm hoping the rounder shape will give more action to the water flow. I'm just going to use clamps on the baffle for now so I have full control over depth and angle before deciding on the location of the adjustable slotted holes.

 

[Bazz]

Very interesting, look forward to you first demo vid

 

[Aggro]

Did a test run yesterday but didn't classify the material small enough. About half of it was gravel about 10mm so it kept clogging up, but it showed promise.
I'll classify to 5mm and try again.

 

[Aggro]

Hi all

I ended up running another test after sieving the material a bit smaller. It sort of worked............kinda, just very slow.
The pipe for the trap was way to large (90mm) and required too much water flow to be overly effective. I did away with the thin aluminum baffle and used a 12mm piece of plastic instead to reduce the volume of water in the trap which did help somewhat. (videos below)

After running these tests, I have replaced the 90mm pipe with 40mm which has made a huge difference (no video yet).

To clean out, I simply turned it on it's side over my pan and used a small watering can to slowly pour water in to the trap which washed it out no problem.

The material I used was from Deep Creek which I had already panned, so I added small lead to it for the tests. Turns out it still had gold dust in it too that I missed when panning it the first time.
Both pipe sizes caught the fine gold dust and lead flakes no problem, it's just a case of refining the pipe size, baffle and water flow to speed up the process. I'm hoping to get to DC this weekend to try it in a real world scenario.

[video=480,360]https://youtu.be/4sx1g0EiSPM[/video]

[video=480,360]https://youtu.be/T_eI_8Z47GA[/video]

[video=480,360]https://youtu.be/DT9603xUV14[/video]