8 inch gravity sluicing

[spaghettigold]

Hi,everybody ,in my earlyer beginner times(i,m still one) i gathered some infos from this forum,maybe i can inspire others too.
Thanks,saluti from europe ;emilio

 

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[spaghettigold]

Great build where is your motor ?
I started on mine 4" with same drums
View attachment 1190003

Oh come,on djipi!
Stop rub salt in to the wounds!
If i had a motor could walk up the river 500 feet where they pulled 250 grams last oktober.
Last years flood not only destroyed some deposits but it also uncovered some old high grade layers.
A hobby prospector coming from turin discovered as first the deposit.
The poor sucker could work it only 1 or two days and had to go back to his obligations.Maybe hi also did not realize the grade of the deposit.
Anyhow the locals had the pleasure to clean the high grade spots and theres still a gram all five classifieds buckets of material and people working it.

Diggings in the high grade spot.


Looks good and portable your new dredge.Hilti frame parts?

 

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[spaghettigold]

second and third testholes

 

[russau]

What a adventure your on! the dredge looks great! Im envious!!!!!

 

[spaghettigold]

Thanks russau,hope your back allowes you to get into the water again soon.

 

[minerrick]

this pic is from last year, this was 100' of 4" pvc, can't seem to find the picture of this year’s set up, which is much shorter than last year, i am running 60 feet 4" pvc with a 4' drop
suction on the head is incredible, like running a motorized dredge, Problem i am facing seems the bends and dips, will load up with material then reduce suction. so disconnect and clean out get the flow goin again, doin by yourself is tough, taken the pipe apart and putting together in the fast water would just ware ya out, it's a laugh, tripin slidin, catchin stuff tryin to go for a ride, so i guess my question is do you find the 8" load up on the bends and dips? how much drop do you have for your length of hose?

If it were me, I'd put some sort of "x" piece of metal on your nozzle (or maybe a "y") to act as a restrictor to ensure no big, weird sized rocks weren't sucked up, and then on your straight sections, use black ABS with threaded connectors. A couple of advantages:

1. no dips
2. blends in very well with the surroundings (the white of the dredge hose can probably be seen miles away)
3. best of all CHEAP

And just use the soft ends for the intake and exhaust.

You would want to nozzle restrictor to ensure you didn't get a plug in the ABS.

 

[spaghettigold]

If it were me, I'd put some sort of "x" piece of metal on your nozzle (or maybe a "y") to act as a restrictor to ensure no big, weird sized rocks weren't sucked up, and then on your straight sections, use black ABS with threaded connectors. A couple of advantages:

1. no dips
2. blends in very well with the surroundings (the white of the dredge hose can probably be seen miles away)
3. best of all CHEAP

And just use the soft ends for the intake and exhaust.

You would want to nozzle restrictor to ensure you didn't get a plug in the ABS.

Yes rick,thats an option i thought about with pvc tubing.We have some artificial waterfalls with almost 20 feet of drop where i could get the force for working some spots where no drop is available.Unfortunately there,s a law that forbidds excavations within 164 feet near such builds.I needed to much tubing and let this project go for the moment at least.
Also i have nomore space in my van but the 2 flexhose pieces fit in because i can bend them,keep in mind i have to travel 5 to 6 hours to get to this river.
But i maybe find time later to learn more about abs and do some special construction pieces.Russau also told me about the advantages of this technique earliyer.
A few months later i found some scrap polyurethane glue cartridges and made this experimental threaded cap using a piece of hose as mold but it was,nt the correct polyurethane mixture and did not work.

I will keep in mind the abs technique for later ,thanks for the suggestion rick and also thanks to the others who gave good advices here with the barrels as pontoons for example,john ,reed ,bill in costa rica etc

as far as the nozzle restriction i would prefer to use oversize rigid tubing to avoid plug ups,i already have a restrictor ring in the nozzle and also the bend in the nozzle that takes away power in low available drop conditions.I experienced some interesting things with the breaking flap of the nozzle that showed me how much power the ring and the bend of the nozzle are taking away.

 

[spaghettigold]

here the second testhole (swimming pool)a bit later that day.It was again too easy to dig-soft sandy material,no hardpack and almost no gold
Also the clay layer was at 4 and a half feet and i noticed that when bedrock( or clay layer in my case )is deeper than3 feet (gravel layer thickness not waterdeepness)it takes a enormous hole at the surface to keep a safe 45 degree slope in the face of the wall that helps prevent collapsing .I think in the future i will stop dredging a spot earliyer when the bedrock is deeper than 4 feet,the overburden is not paying and at the bedrock there,s not a very good amount of gold to justify the work

 

[spaghettigold]

here i used both hoses conected with my semi selfmade conections that worked pretty well

Here,s a vid of the second test hole

 

[bill-costa rica]

emillio
i thought your sluice had more water in it . at the end of the video you had 3 or 4 rocks kicking up tails in the sluice. is there any way to stop that and get more water?

bill

 

[spaghettigold]

correct again bill

In the second vid i had much less drop available then in the first vid of the floattest location.Normally my mining partner makes the sluice tender but he interrupted his work to shoot the video.
Maybe a second 4inch hose could bring in moore water if no sluice tender was there.
Later i worked also in a spot with even less waterforce and had the problem that the undercurrent section began building up material,also light sands by the way.And if my buddy did not constantly surveille the sluice ,the rocks would build up for shure.We tested only 5min ,catching the tailings and we where loosing gold.
We solved the problem by raising the flare till he was straight so that that water and especially the gravels could go thru the flare without a dip.
The second measure was to place a 4 inch rather flat stone under the breaking flap of the suction nozzle,it compensated the power loss coming from restrictor ring and bend of the nozzle.Difference was huge .Before placing the distance stone under the flap,when i had to bend the hose more then 45 degree to be able to dredge up a specific portion of material,the bigger stones in the hose almost stopped,but by opening the breaking flap it moved again.In that low available drop spot the breaking flap became a sort of throttle. It,s all a big compromise in the gravity departement and ouf course the spot with the most gold was the spot with the less drop available...


When i had to bend the hose like in this picture, i lost too much suction power and the material started to build up in the hose. Depending on how much material i would let build up in the hose,the stone under the flap solved the problem,if more material was in the hose i opened the flap completely to clear the hose,and if i let even more material build up i had to straighten out the hose again .But the sluice tender was always required despite all the corrections.

 

[djpitr]

Great video , look like you need some weight belt
So on the video , whats the head difference between sluice and nozzle ?
Deeper you dig less suction ?

 

[spaghettigold]

To be honest we did not measure the drop,we just tryed it. I have to guess...3 feet.?4?

weight belt would help going down ..would it be hard to come up all 10 seconds to take a breath with a weight belt?How many kilos /pounds are required?

For the suction ,if you go deeper the waterpressure should compensate the loss of drop regarding the suction of water,but not for the material.
Practically i experienced that when i sucked up the material laying under the hose (left,middle of picture) and a bigger portion of the hose was laying downwards in the water creating a big surge for the material to climb up ,i lost another great portion of force.

 

[russau]

the shorter and straighter you keep your suction hose the less restriction there will be allowing for more water pressure to do the job at hand!

 

[spaghettigold]

yes russau,sharp bends are killing it when already low drop is there

 

[djpitr]

It just look like in video that it would help you stay under water , i actually dredged last weekend on friends 4" , Mine First Time and i didnot have air just snorkel like you , and i could definitely use some weight to keep me from moving with the water flow , you can always stand up to take breath if you not in deeper hole

 

[spaghettigold]

hmm..maybe i,l give it a try in the future,at least it,s good i have one when i need one.

 

[spaghettigold]

another test location using a 4 inch ,16 feet pvc hose with a good 2 feet of drop (c.a)

 

[ratled]

SG I have been thoroughly enjoying this thread since I have found it. What are you finding you need as a minimum and as preferred drop to get the suction you need to work the gravel?

TIA

ratled

 

[spaghettigold]

hi ratled,thanks

Difficult to say cause i never really measured exactly. Also it depend on how hose can be layed out in the river bed.The dips and bends.But better to have an little moore drop than needed and be able to adjust the sluice.
On the 26 feet long piece of 8 inch i guess 4 feet ,both hoses (52feet) maybe 6 feet and then adjust the height of sluice to slow the waterforce in the sluice at the beginning of the digging,later when a big hole places a bigger portion of the hose in the digging hole,creating earliyer mentioned surge for the material in the hose,or when working material that requires you to bend the hose ,you can lower the sluice .
But it works also with less drop and as long that there,s gold in the ground and at least 2 feet of drop i try to find a solution ,like building dams for example.
Or use a shorter piece of hose if possible(or a longer piece if it allowes me to catch a good piece of additional drop)

 

[spaghettigold]

and another one