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Question on bigger Gold, ribbed matting and Sluice Boxes
Free Fossicker Forster  
Posted : Monday, 13 August 2012 11:09:48 AM(UTC)
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It seems your ribber rubbed matting (and similar) is good for fine gold. What if you (should be lucky) and throw shovels full of gravel containing bigger lumps through a sluice box made of this stuff? Let's say a 0.2 grammer, a 0.5 grammer and a 5 grammer. If your flow/volume and box angle is set nicely for the fine gold, how will the larger bits behave? Will they just sit there like larger stones perhaps, or gold on bedrock? or will they pass through undected across the fine ribbing along with the heaps of gravel your throwing through (maybe too fine for bigger stuff to lodge in)? Is this where a few larger riffles could save you?

Edited by user Monday, 13 August 2012 4:52:44 PM(UTC)  | Reason: Not specified
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simon  
Posted : Monday, 13 August 2012 12:05:47 PM(UTC)
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i've had gold just sit on my metal flume right where i've dumped a shovelful of paydirt.

the gold is just so heavy it doesn't go anywhere. you get a lump that's even bigger, say .3 grams, and it ain't going anywhere - it's just so heavy.

i've observed the same when i've water roaring thru my box, or just at a trickle. the exception would only be the really thin flake. this may tumble off if you have a water flow that is not even across the sluice width and you have it running at full throttle.

anything big, say .1 grams and above, would probably be picked up in such a manner before it gets to the riffles and matting. i always pick off the bigger bits but in reality it would take a lot to dislodge them.

i can dump bucketfuls of unclassified paydirt onto my sluice and the gold that was sitting on the matting is just as it was once all the gravel is washed off.

if anything does take off you have riffles to catch it. i have never found gold past my 3rd riffle. it stays where it falls.

at cleanup if you find gold at the bottom end of your sluice something is going wrong.

i don't even have ribbed matting but if it's fine gold you are on to this may help to show if you are getting any gold.
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mineforgold.co.nz  
Posted : Monday, 13 August 2012 7:21:25 PM(UTC)
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If you have ever seen a dredge with underwater sluice you'd wonder how it catches gold, but apart from maybe the very fines the only time gold escapes is when you accidentally tip the sluice on an angle. As Simon said gold is heavy stuff.
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fastangler  
Posted : Friday, 17 August 2012 4:32:52 PM(UTC)
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the heavy chunky bits will sit there but sometimes if theyre flakes the water catches them and they dont stop.ive found quite a few at the bottom of my box and i didnt see them cross the rubber mat.its scary to know that your catching all the fines perfectly but some nice flakes could of rolled out the back of your box
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simon  
Posted : Saturday, 18 August 2012 8:31:47 PM(UTC)
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fastangler:

i'd be keen to see a pic of your sluice.

how big are the flakes that get to the bottom of your box?

i know what you mean with the flat flakes catching the water. big flat flakes are the only big stuff that gets down to my 2 or 3rd riffle.

everything else i can pick straight from where it falls pretty much in any sort of flow, raging or trickling.

the only classifying i do is picking out the odd big rock as i feed the sluice.
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fastangler  
Posted : Monday, 20 August 2012 3:57:07 PM(UTC)
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hi simon,i got one of jw's boxes.
0.1's and 2's are the ones that tend to do that in my box.dont get me wrong if i see em i pull em out but some just ride the wash down
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simon  
Posted : Monday, 20 August 2012 11:09:04 PM(UTC)
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if the gold that big is riding the wash down the box i'm wondering if you are overloading the sluicebox?

i'm not too familiar with jw's boxes but i'm sure it's got riffles as well as some black ribbed matting. gold will move off black ribbed matting easily enough but it should be getting caught behind the first few riffles not flowing past.

the only other thing is the angle of the setup of your box is too much. each box seems to cope differently with the slope depending on its setup of riffles/matting etc plus its total length/width/waterflow.

i was running mine really steep the last couple of days. i kept an eye on a big and smallpiece of gold and they went nowhere even with me dumping buckets and shovel of paydirt over them.

hope that helps. bummer to see any hard found gold float off that's for sure. i'm always keeping a close eye on my sluice. you never know when a rock has shifted and the box upset. usually i bed in down pretty solid so no problems. once i dug up a silver 1848 coin from a crevice. it only caught my eye as i saw it flicking over each rifle as it was so light.
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Golddigger7  
Posted : Monday, 15 October 2012 11:12:30 AM(UTC)
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Yeap, gold is slippery stuff sometimes, and the problem gold is usually that, finer fluffy flood gold. That's because its weight to surface area is low, the surface area tends to make it work like a sail in the wind, for want of a better description, and it tends to not settle as easily.
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kiwijw  
Posted : Monday, 15 October 2012 6:38:08 PM(UTC)
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Hi guys, My boxes are only 800mm long & made for easy back packing if you wish to get to those more remote & more difficult areas where hopefully they havnt been too thrashed. I now have them with a removeable flare that when attached gives you a bit more length in the box.

UserPostedImage

UserPostedImage

UserPostedImage

Because my boxes are quite short you need a more gentle flow & I recommend pre classifying the material you put through.

UserPostedImage

UserPostedImage

By pre classifying you can have a more gentle flow & get no block ups & this greatly helps your fine & flakey gold recovery. It isnt rocket science that if you have a torrent going through a short box, or even a long one, that you ARE going lose fine flakey gold.

UserPostedImage

UserPostedImage

As Simon said, Dont over load the box & what Golddigger7 said about fine flakey gold is spot on.

Good luck out there

JW :)

Edited by user Monday, 15 October 2012 6:46:16 PM(UTC)  | Reason: Not specified
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