Panning drains (and raking in the pyrites)

[auriphile]

Had a lot of rain lately, and it's too flooded to get near my favourite local spots. I spent a while mapping the local road drains so today was an ideal opportunity to start testing them.

Old mate and I spent a couple of pleasant hours sample panning one section today. Nice spot to work on a hot day - but no gold. Loaded with pyrites though - the unmistakable brassy look and the harsh flat crystal planes. Not pretty like gold (and I'd be able to hear gold if I had that much in a pan)

Not a wasted day though - now we know another spot with no gold! (Concrete) Drains are interesting because you can easily thoroughly check them - unlike natural waterways. So we'll never have to worry we may have missed something.

The section of drain we checked runs though an area I've surveyed before - heavily mineralised, mostly iron and copper. I wasn't surprised to find no gold. The highest collection point for that drain is about 700m. Now I'm even keener to try some of the other drainage systems, many of which start around 800m.

Anyone tried road drains? Any tips? Cheers

 

[auriphile]

I took a sandwich bag's worth of samples from each side of where drains ran under roads - then panned them out. This morning we went and checked out one of the usually dry creeks which had showed good gold in the drain samples. Nothing spectacular but a few dozen microspecks in every pan - everywhere we checked. For a tiny creek it sure has a lot of flood gold... (yes, those specks are gold).

 

[auriphile]

Lots of microspecks (not "Lots"). Still - a fun and healthy (if you don't drink the water) way to spend the day!

Gunna haveta:-
* move upstream
* tune my sluice and keep re-running the capture bucket
*build a Miller table

 

[auriphile]

Improved fine gold recovery technique.

Gentle use of the pan (and detergent) reduces most of the lights. Then there's the black sand. Around my area the black sand is magnetic (Iron Sulphides?), so dragging a bag with a magnet in it removes the black sand. That still leaves a lot of fine material to separate from the gold - which I can recover using side-taps and a snuffer bottle, but it's time consuming. Instead I found using the hot air gun to dry the concentrates (before removing the black sand and tiny iron stones) allows you to use dry blowing to further concentrate the heavies. Much quicker and easier.

Tip: concentrate with the pan as much as possible before removing the black sand because the black sand helps protect the gold when you're panning (sits on top). Without the black sands the fine gold just washes out . I collect the black sand for just that purpose - add it to the pan to keep the fine gold in while I remove most of the lights, then remove the black sand with a magnet. Lots of black sand makes it much easier to keep the fine gold in the pan.

First (poor) picture is layer of gold and black sands floating in a few millimetres of (acidic) water. A bit of surfactant (surface-active agent, $10 word for detergent) fixes that.

 

[Stingray]

Good tip about keeping some black sands to trap the fine gold.

He's something you might want to try to maximise fine gold recovery. Instead of putting a magnet in a bag and into the pan, I place it under the plastic pan and drag the black sands across and up the other side of the dish till they are out of the water and near the lip, then I pull the magnet away and flick the sands out with my thumb.

Finessing it further, rather than just putting the magnet under the main body of sands and dragging, which can carry gold with it, I tilt the pan slightly and put the magnet on the uphill side and away from the sands a bit to make the black sands jump up to the magnet. That tends to stop fine gold getting trapped and dragged away in the black sands in the first instance. As you drag it uphill you can generally see if there is any residual gold amongst the sands. If there is, and it doesn't drop as you drag it, then make it jump again. The gold should get left behind.

 

[auriphile]

Good tip about keeping some black sands to trap the fine gold.

He's something you might want to try to maximise fine gold recovery. Instead of putting a magnet in a bag and into the pan, I place it under the plastic pan and drag the black sands across and up the other side of the dish till they are out of the water and near the lip, then I pull the magnet away and flick the sands out with my thumb.

Finessing it further, rather than just putting the magnet under the main body of sands and dragging, which can carry gold with it, I tilt the pan slightly and put the magnet on the uphill side and away from the sands a bit to make the black sands jump up to the magnet. That tends to stop fine gold getting trapped and dragged away in the black sands in the first instance. As you drag it uphill you can generally see if there is any residual gold amongst the sands. If there is, and it doesn't drop as you drag it, then make it jump again. The gold should get left behind.

I dry the concentrates with the hot air gun (and blow off the lights) before I remove the black sands. If I try and remove the black sands when the material is damp everything sticks to the magnet. The hard part is removing the very fine powered ironstone (see attached pictures). Most of the gold is superfine - there's a little over 2 grams in that pan - very little of it can be seen as individual specks without a microscope (see attached picture).

Note that I'm using a small magnet - I did try a mate's "fishing" magnet. It pulled everything out of the pan (and we had trouble removing the bag from the magnet afterwards). The black sand is very fine, but most of the gold is even finer.

Previously if I couldn't see a few specks in a pan I'd give it back to the River Gods - now it goes in the concentrates bucket because there's usually more invisible fine gold than there is in microspecks.

 

[Stingray]

If I try and remove the black sands when the material is damp everything sticks to the magnet.

I do it with water in the pan so the material is all underwater, and use a very strong magnet. You can control the magnetic intensity, and hence the amount of material captured, by varying the distance between the magnet and the dish.