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Keene 3 stage sluice setup


#1

hi i have an 5inch keene with the 3 stage sluice.I have put about 60 to 80 hours on the dredge each time having at different angles of the sluice or the gap going into the under part at different length openings no matter what i do it just clogs up with materiel ive never got any gold out of that part either.does any one have any tricks of mods to make it work better thanks chris


#2

Is your tail end, discharge below the water… causing a back pressure restricting flow?


#3

Iv had 4 keene,s 6,5,& two 4,s …choke you need to have as open as you can & you will no this by watching the sluice work if the rocks on the top section are not getting moved down close the choke a little until they are , having someone dredge for you while you watch is a big help .2 things also spring to mind when you mentioned the undercurrent box getting blocked up 1 answer could be you are simply sucking up to much material especially black sand the other could be that you have the sluice set to far back in doing this you think the rocks will wash off easier & that could be partly true for the top section but the bottom section will suffer for it as its submerged to much underwater to allow the silts & black sand to clear properly , its highly unlikely there is something wrong with the dredge , once you find its sweet spot you just leave it or mark where the sluice sits if you have to take it apart to transport…something else springs to mind , the angle of your powerjet/flear try running that as straight as you can the more angle you have on that the more you slow the flow before it go,s over the sluice I usually have myn so its just under the water as you don’t want it sucking air.


#4

Also have your throttle at 3/4


#5

sweet we run the pumps about that rpm and will just keep playing around till get them right will use your advice tho. if using the hot water tho i have 1 pump at 50%ish throttle and 1 pump at 100% to get the temp of water up


#6

you mean 1 throttle at 50% ? , needs to be higher both at 85% 100 will likely just shorten the engines life if you need to run it that hard you probably have to much water going through the exchanger which is why you need 2 of them


#7

i only run the pumps like that if using the heater .I have an valve on the heat exchange and to get the water hot it has to be an tiny dribble but with 2 like you said then i can run both at the 85 like you recommend and go from there. thanks for the advice


#8

A couple of things you might want to consider is upgrading the screen on the 3rd stage. Keene now sells 3mm woven wire screen instead of the punch plate in the stock setup. I’ve been testing this new concept as well as some other mods to the 3 stage sluice for about 4 months now and it has greatly increased the recovery of fine gold and processing ability of the dredge.
This has the affect of increasing water into the 3rd stage which increases flow through bottom stage. The other advantage to this is it creates more drag on the water column which results in more of your gold being bypassed into the 3rd stage.
The design by keene on the 3 stage sluices was for material to load up slightly under the 3 stage as this helps regulate the feed of light materials through bottom sluice and ensure stratification of material before being processed by the Hungarians and expanded metal of the bottom stage.

You might want to think of adding more throttle say 3100- 3200rpm for most applications or higher if stripping overburden and when your on the pay gravel throttle down to 2900 -3000rpm and take it a bit slower with material feed. If ur in a area of not much fine gold just go hard.

I must disagree with the suggestion to run your flare as flat as possiable. You actually want a bit of an angle as this helps slow down the water and causes material to well up and drop into the box. If u need more flow over the riffles then add pitch at the sluice.

I’ll try and upload some pics to show ya what I mean

Cheers


#9


#10


#11

choice thank you our dredge does have the mesh at the top but riffles at the end not the expanded mesh like yours. are you from Dunedin by an chance seen an dredge like this with the custom intakes and mufflers for motors on an trailer the other week


#12

Yeah mate that’s me.


#13

Loving the set up bro , may have to copy , not sure about the headers I like the quiet too much , hope all is going well , will try catch up next time in town


#14

Yeah she gets a bit loud alright when your not in the water but with the headers and some other mods managed to double the HP of those engines which has allowed me to run taller and wider impellers on the pumps meaning more suck in the deep spots.


#15

Some people don’t understand how the flare works & just leave it hanging down low the way the flare & hanger is designed is to be able to adjust it so what I meant was start up as high as you can & play with it , its always a bit of a trade off would you prefer rocks left sitting ontop of your riffles boiling out gold or run the flare a little flatter , speed the flow up get rid of the rocks , what would be worse a steeper sluice vs a flatter sluice with a faster flow …trade offs :slight_smile: trick is to find the sweat spot , iv got rock rollers on 2 of my dredgers now that made a big difference especially for those annoying flat rocks that like to partly drop into a riffle & not move , your expanded mesh will have the same effect .Don’t quote me on this but I believe the rule of thumb is for every meter of sluice equals 1 inch drop so sluice 2 meters long should have a 2 inch drop i have a sluice 3 meters long pretty sure the drop is very close to 3 inches but I did adjust that a little like the keene slide it back for more drop forward for less now that dredge runs with the flare just under the water & id say %80 of the gold get trapped in the first meter & the rest in the undercurrent , so little makes it to the back section it only gets emptied once a week .