Hi team i have a 5 inch keene looking at building a whole new sluice box for the keene frame and pumps and upsizing hose etc to make it a 6. Thinking about doing a dave mccracken double mesh system for better fine recovery. What would you do to make the ultimate sluice box. For mostly fine gold but also to catch any nuggets that come threw.
Aint the keene 5 and 6 the same and just need to swap the flare and jet?
Could save some coin and just redo the riffle sections
Not meaning to tell you how to suck eggs as you will know this already, but it may “help” others. The “secret” to fine gold recovery is to have the finer material separated from the main flow down the box. The strong, aggressive main flow is needed to have the bigger rocks & material wash on down & out the box…along with a lot of the finer gold.
This is accomplished by either an over/under box set up where the main flow & bigger rocks & material go down the top box. At the head of the box the finer material drops down through a perforated screen to enter the lower box where the water flow is a lot less, allowing the finer gold to drop out in the gentler flow of water & not get washed right on down & out as it mostly would in the much more aggressive flow of the top box.
Or the “older” triple side by side box where again the main box is in the middle & the finer material is diverted to the two side chute boxes in a much gentler flow of water allowing the finer gold to separate & settle out.
You could argue too that the “older” crasher type sluice boxes, not the flare type, are better at fine gold recovery in that they smash up clay material, freeing the gold, at the head of the box before it gets into the recovery riffles.
Goggle is your friend. Do some searching.
Exactly what I am building at the moment JW. An under over sluice system. Only to handle a two and a half inch dryland suction nozzle though. Will be working on the dry banks targeting flood gold, Buller River. But as I will also be working bedrock on the banks in a lot of places, with bigger gold. I have two matt/riffle systems I can swap out when it suits. One lot for fine gold only. One for fine and coarser gold, and by swapping around, I can adapt the top sluice for coarse gold and the bottom one for fine gold, and coarser gold too. Its still a work in progress. But almost there. Just about finished paddling pool trials on the back lawn. And then it is off to the Buller river, for trials there. Not where I will be finally working. But close by to where I live. Want to see how the gravel separation goes. Will post some more on the thread. Playing in the Paddling Pool soon. We have had so much rain up here it has slowed my fabrication and trials right down.
Had a Keene Five inch triple, great dredge. A little heavy but man it did the trick on all sorts of gold. And yep my sluice system has a crash box. Im a long time fan of crash boxes. They create a reverse flow at the top of the sluice and really smash things up. My bottom sluice feed is also a reverse flow.
Cheers Trev aka “The Mad Hatter”
In answer to the original question. Yep as JW says you would have to incorporate an over/under set up. Classifying what goes down to the under sluice. Or possibly copy a super max Keene 6 inch. Hopper at the bottom end of a single sluice system, and by means of a venturi system pumping the classified material that goes into the hopper, back up and into two side sluices. A super max simply uses a similar system to the old five inch keene triple. Two side sluices, just gets the classified material there in a different fashion. If you google Keene five inch triple gold dredge. You will see the setup. There are a couple of vids showing one in action.
Cheers Trev aka “The Mad Hatter”
I do have a 5 inch 3 stage and yes its the same box as the 6 (under over) no matter were I have the inlet feed for the under sluice set up or how slow I feed the dredge I lose gold out of the bottom stage even some larger flakes…I was thinking or making a whole new box alot deeper than keene and longer. And useing dave mccracken double classification method. Like 9mm mesh whole way along that’s 50mm(adjustable height) over a 2mm mesh then rifles/ expanded metal over moss or ribbed matting( big wright up about doubleclassificationon goldgold.com website and have talked personallywith Dave about it. Also good video about it in youtube showing how 8 inch dredge build with it). With maybe 3 exposed Hungarian riffles at the back for nuggets… I have done alot of research I was just wanting to see what others would do for there own ultimate sluice box. I have thought about making a sump system too like the super max and feeding it threw 2 le traps on either side.
Gidday laidlw. I have just have a look at the Keene three stage system on a PDF file put up by Keene. Now I don’t want to tell you how to suck eggs. But I am not impressed with their third stage at all. It appears to me that it aint very long at all. About a third of the total sluice system. So Keene are asking that section to do a lot of work. I am aware from when this system first hit the market, that many had trouble with the flow adjustment to the 3rd stage system. Seems you also have that problem, so it hasn’t been rectified by Keene.
I have never had that much faith in Keenes Riffle system, to me the riffles have always been to high. And I am amazed to see that they actually have riffles in that lower stage of the Stage 3. Bugga me, it doesn’t need riffles as it is dealing with classified material, Im not sure what size they are classified down to.
Now when I was operating a Keene 5 inch triple back in the late 80’s
what we did on the side sluices was put what we called spotter mats at the head of each sluice, this was in front of the riffles. Yep Keene still had these enormous riffles in the side sluices. Well guess what, one hundred per cent of the gold that was diverted to the side sluices after classification, was caught on the spotter mats. Many a time I would pan out the material from the sluices separate. Guess what. Not a bloody spec of gold, even micro gold. The spotter mats were a miserable 10 inches long. Ribbed nylon door mat stuff actually. That stuff loves gold. I have written before about the affinity between gold and nylon based carpets. Gold is a super conductor of electricity, water flowing over a nylon based carpet creates static electricity. That has something to do with it. Some sort of physics magic beyond me. My advice, biff out the riffles. And bang some ribbed nylon based door mat stuff in, frig it even catches flakey gold like there is no tomorrow. Velcro does the trick for sticking it to the sluice floor, Ado’s F2 is your friend. Even mix in a bit of ribbed rubber or thermo plastic with riffles and grooves in it. Gold Hog or the green stuff Dan at Dredge NZ sells. Don"t have a Keene riffle in sight. Even when I was black sanding on beach gold I used nylon based material. In that situation polar fleece did the trick. The stuff trackies are made out of, the inside fluffy bit, not the outside. Its not gunna cost you a fortune to achieve what I have outlined. And its gunna be a lot cheaper than converting a five inch to a six inch, and you are gunna still have the same loss of gold. With a six, probably more. Without getting a big head, I consider myself an expert on catching fine gold. In fact any gold. I have mentioned it on here before. I was responsible for “Gold Cube” if there was no me, there wouldn’t be a gold cube.
My bona fides. 30 years dredging, 20 years black sanding. Both at the same time actually. Black sanding all winter and when the river was flooded. Dredging all summer when circumstances allowed. How much gold have I recovered. I stopped counting after around 300 ounces. Sadly all when gold prices were a lot lower than today. And of course overheads were high. Right off to find some pics. You mite like to follow my “Playing in the Paddling Pool thread” it will get pretty active any day now. You will see how I set about building and designing an efficient system.
Cheers Trev aka “The Hatter”
Hi @kiwijw and @kiwigold what would your thoughts be on an under and over set up be on a dream mat? I’ve been thinking of doing it to mine. I know people seem to say no classifying needed on dream mat but I’m not convinced. And I also know there’s a few of you who don’t realy see the point in dream mat but that is what I have and I’m to much of a tight arse to buy a riffle set up. I can make a similar seperator to the keene super sluice with what I have laying around. I’d just rather not try make a riffle frame and go buy matting etc.
Cheers for any input by yourselfs or others
Can’t really help much as I have had no experience with dream mat. So angle feed rate, classification is all un charted territory to me in regard to that stuff. Some guys swear by it, some rubbish it. Mind you that can also happen with other catching mediums. Only way to find out is go for it, see it as a challenge and think out of the loop and who knows what you might come up with. Best of luck. Keep us posted.
Cheers Trev aka “The Mad Hatter”
Thanks trev will do. I managed to track down punch plate etc so now to put it together
Hey mate - The 5 inch and 6 inch mini dredges which you are referring to are the same dredge setup as mentioned by gogold
They share the same box. In my opinion the 6 inch is lacking in the size (width) of the box it runs.
The 3 stage system by Keene is an over under setup and they are one of the best for fine gold recovery. They eat all over the old triple side by side boxes if you have them setup properly. One of the big issues with the old triple side by side setups were the height the sluice sat out of the water and this is where you loose tons of efficiency ie loss of suction and rock jams. they also didn’t operate an over-sized powerjet as well as other pitfalls
Let me know if you want more info on how to properly setup the 3 stage. there is a bit of fine tuning not just with the box but also with the flare angle and depth your powerjet runs within the flare.
The double screen fine gold recovery that Dave Mckracken talks about works well however its very heavy and you will require extra floatation to run this setup. There are also a ton more concentrates to deal with and you have to be careful with feed rates and really if your in ultra fine gold areas they are ideally suited. He used to run this setup very well in places like Cambodia where its mainly flour gold
You don’t need an under over system for dream mat, yes dream mats lose gold classified and unclassified and it’s considerably more than David Peterson let’s on as I’ve done lots of testing, it especially struggles in black sand rivers. what you need is a seperate medium behind to catch the fines!
Check out my video on YouTube to watch this sluice catch 97%+ of gold, that’s most likely the highest collection rate of any gold medium in the market.
Where dream mat does excel is in slow feed rate concentration, if you spoon feed onto the mat it is by far the best recovery system.
Agree with ya there Gav re the dream mat.
Theres a reason all the main dredge manufactures stick to the tried and tested raised expanded metal over carpet or miners moss in there dredge sluice setups because it works otherwise they would all be using these gimmick mats which they dont!
Hi gav I hoped to hear from you also as I see u use the dream mat alot and seem to prefer it.
My main concern with non classified material is big stones/rocks deforming and disrupting the rubber cells.
I will try track down your video as I don’t see a link and then I might private message you if that’s OK.
I used dream matt on the top deck of my under and over 6" custom built dredge. never again. I lost 50% of my gold. This was borne out when I replaced the dream matt with conventional riffle system. Dream matt says it can handle classified and unclassified pay in all flow conditions. My experience is that that is a pack of lies so would never use it again period. If a manufacturer lies about the performance of there product in any aspect I don’t trust it. After 3 x 34hr clean ups the lost gold added up to around 54 grams.
Look up Aotearoa prospecting supplies on youtube
Interesting you say that about the dream mat. Did you run the heavier commercial mat or the lighter sluice mat?
I purchased a sheet of the commercial mat to go in the 1st and 2nd stage and fitted twin sluice mats in the 3stage.
Everything ive seen of them they seem to work and the commercial mat was rated to 70cube per hour. Found most of the guys who complained weren’t screening it.
Yet to try it properly as i have had pump issues and really run out of time this season. But the little bit i did do with it seemed to catch some really fine gold
Im screening 8-10mm at the head of the box and for the under flow. And 14mm for the 2nd stage which i am going to drop to 8-10mm as well and put a few 12mm slots in it for the lower 3rd to catch any nuggets.
Im with you , i dont beleive it can handle unclassified material, infact ive watched gold moving forward on it when rocks hit it this causes a shock wave which causes the gold to jump forward id imagine in a classified clean up system it may work, is good for lighting the fire with tho
That doesn’t surprise me webby. Im not a fluid engineer by any means but i could see a large rock could cause it to do that and also disrupt the vortex and cause cells to flush out.
That is why I decided to screen the box off so the larger material can roll right on over the top with out disturbing it.
Just seems to make sense in my simple little brain
If I was going to make another sluice Specifically for fine gold I’d make a sump type setup like Keene have brought out , not sure if you have seen it but it classifies the smaller material so that it falls through into the sump slurry below & gets pumped over 1 or 2 separate low flow sluice box’s , the bigger stuff stays in the main sluice.
Iv got a 6” Keene & a 8” that has been built around the 3 stage system …all my gold is mostly fine , been using these setups for over 10 years and put simply they work , Some in heavy black need to play with the setup a bit more but if you’re wanting to think outside the square a little then a sump option would be the go .