A few newbee questions about sluicing

[Goodyguy]

My Keenes are set up that way, but most of my homemade stuff is sans riffles. The expanded metal IS the riffles. Very little water to run one, and it helps break up clumps pretty good. I work in sheet metal so i have an unending supply of this stuff, but it is available for most anybody at any scrap metal yard. Also online.

Would you recommend dredging into a sluice without riffles? Do you make your sluice longer than normal? Got any pics?
I like trying new things.

GG~

 

Amazon Forum Fav 👍

Cry Of The Eagle: History And Legends Of The Cherokee Indians And Their Buried Treasure - Grab it through Amazon!

[beaks]

i tried that and with the large flow of a dredge pump it just washes everything off the end of the sluice except when you get lucky and a flake or two gets stuck.

it might work for a really long low pressure setup(8 or 10 feet and 20 to 40 gpm) running into a tub but a normal dredge will blow everything over expanded metal riffles.

been there done that and i really didnt like dumping everything out that i put in without getting at least some black sand or chunks of quartz.

[/quote]

The expanded metal IS the riffles. Very little water to run one, and it helps break up clumps pretty good.

[/quote]

 

[kiwi jw]

Hi Guys, As I have said before you realy only need enough water to wash the material on down the box otherwise you will lose fine gold. Yes a dredge will put more water down your box even a 2", & in a way you need that extra bit of flow to make sure the bigger stones wash on down & out your box. A 2" will put stones of nearly 2" size down your box & to get those on down & out your box you need a bit of grunt in the water but expect to lose fine gold. I made a little classifier header box for my 2" so that there was no material going down the box larger than 3/4". The change of water direction took the sting out of the velocity of the water going down the box & over the riffles & made for good fine gold recovery. This is the same box as in the river sluice above with the classifier header box fitted

I have played around with all sorts of riffle sizes & configureations & learnt that to get most of the gold & especially the fine stuff is to preclassify the material & use a water flow that is just enough to run the material down the box & a riffle size that is just big enough for a gentler flow of water. I have even used a large expaneded mesh as a riffle system on its own in a river here in New Zealand that has pretty fine gold & heaps of fine black sand. Tailings from a whole lot of old stamper batteries that discharged their waste into this river system in the early days. They also lost heaps of gold in their tailings. This required a gentle flow of water, so as to not wash on the very fine gold. Therefore I needed a low riffle so the water flow would still wash the waste material on but not strong enough to wash out the fine gold.

This is the set up with riffles fitted

This is with the large expanded mesh as riffles.

Water flow turned off & the fine black sand on the down stream side of the large expanded mesh & very little bigger material. "V" ribbed rubber mat at the head

Fine gold recovered

You need to weigh up the size of gold that you are hoping to recover from the stream, or what size gold the stream has you are going to work. If it is mostly fine & flakey then you need slow water, smaller riffles & spaced about 3-4" apart so the slower water can keep the material from over loading the riffles. If the gold is a bit bigger then you can use a higher riffle & spaced closer together & a stronger flow of water. It is important to have that shuffling, vibrating action between the riffles in this situation. You cant really have one box that will suit all situations. Unless you have different riffle set ups that you can chop & change. "V" ribbed matting is good to use as is a fine expanded mesh. Or a combination of all. Here is a little 32" x 9" box I made with ribbed rubber mat at the head of the riffles. This shows up any gold getting caught up in it or passing over it. An indicator that gold is actualy going down you box. If you arent seeing any gold here then you need to dig somewhere else. After the "V" ribbed matting is the riffles that are on top of a fine mesh that is on top of astro turf type carpet. Being a short box it is really only a slow water box & the riffles are only about half an inch high & spaced about 3.5" apart. Works well for fine gold as long as the flow isnt too strong

If you are going to run faster water then you will need a longer box as well. My box above with the wooden header box is 44" x 10" & it will handle material shoveled in to it but you need to pick out the bigger stones.

Happy golding

JW

 

[Astrobouncer]

Thanks for the pictures and info. The first sluice I built was made for small streams so its riffles are very small (1/4"). Mine started as a copy of this sluice here: http://forum.treasurenet.com/index.php/topic,176317.0.html except for the fact that mine has some extra 1/4" riffles in the middle. I also use expanded metal and some kind of outdoor carpeting under the end/middle riffles. Also use a small piece of screening between the two toward the end, which helps trap the real small stuff. Here's some pictures of it: http://img30.imageshack.us/gal.php?g=imgp1461a.jpg

I have another one in the works that is either going to to be using 1/2" or 3/4" riffles at a 45 degree angle, for rivers with higher flow. Also using expanded metal and some kind of miners moss substitute when I find a cheap one.

 

[Jeffro]

My Keenes are set up that way, but most of my homemade stuff is sans riffles. The expanded metal IS the riffles. Very little water to run one, and it helps break up clumps pretty good. I work in sheet metal so i have an unending supply of this stuff, but it is available for most anybody at any scrap metal yard. Also online.

Would you recommend dredging into a sluice without riffles? Do you make your sluice longer than normal? Got any pics?
I like trying new things.

GG~

Kiwi's excellent pics above show the same as one of my setups. You see the one with the LARGE expanded metal riffles? Thats the kind I like. No Hungarians, but as the pic shows plenty of riffles. I've also mentioned before I prefer not to see whitewater in my box, and when running this setup in a dredge I use much less slope and let the water run deep. Plenty of force to move big rocks, as there are no real obstructions like Hungarians, but gangs of small riffles from the expanded metal makes for excellent fine gold recovery. Looks like Kiwi does quite well with this setup too!

Since we're on the subject of out of the ordinary, I also like to use perforated sheet in the top third of my box, set about an inch above the tops of the riffles. This classifies the material and slows down water at the head of the box, and the larger rocks just roll right on down. You're catching your fines first, then your larger pieces. Two things I've noticed about this kindof setup. 1- if you're in an area with known larger gold you probably don't wanna mess with this. I know gold is heavy and all, but seeing pennyweight nuggets down in the lower third of my box is unsettling, to say the least! And second, its a bear to get tuned just right. Up here in Oregon we have all kinds of different gold and I've hit so many areas that certain setups just seem to work better than others. In the Bohemia area, you'd be hard pressed to find anything larger than the head of a pin, and thats where this setup works well. Very little coarse material to run through the sluice and very few larger pieces to worry about.

 

[Goodyguy]

Thanks Jeffro,

Very informative reply.

GG~

 

[beaks]

a punch plate is always a good idea when you dont classify your material.

 

[kiwi jw]

Here is a set of fast water riffles I made. They are about 1" high. Set at a 45 degree angle with a bottom "foot" to spread over the fine expanded mesh that I use on top of the carpet & beneath the riffles. The idea is to close off the slight gap that would otherwise be left between the bottom of the riffle & the lift of the expanded mesh. That way sealing off so there is no gap for water pressure to wash out fines & gold trapped on the down stream side of the riffles. The little top lip should not have been parallel with the bottom foot but should have had a slight up hill kick to keep the water "lifting" & so cause tubulance between the riffles. Being parallel makes the water flow over the riffles too smooth.

Here they are in action with fast water from my 2" dredge set up going through my little highbanker

And gold recovered

And here the smoother action of slow water from shoveling into the highbanker with the water flow from the spray bars in the highbanker.

And gold recovered

Fast water riffles generally need to be closer together than smaller slow water riffles as in a river sluice. Take a look at how much closer dredge riffles are than a river sluice. Notice also how the black sand is packed tight into the down stream side of the first few riffles

Happy golding

JW