Taiwan gravity dredging,.. interesting

[jcazgoldchaser]

Using 2 hoses, creating more suction?



Floating the hose with waterbottles

 

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[NeoTokyo]

Kickass vids, the first didnt have much of a drop but the two tubes helped him gain a stronger head it looked like.

Thanks for posting!

 

[russau]

he needs to have a longer jet (10 times the diameter of his suction line) to get the maximum suction through his line! mulitiple lines for the feeding of the jet is a very good idea~

 

[NeoTokyo]

Im thinking though, having double lines feeding wouldnt increase much if any as the same volume of water is merging into a space with the other volume that happens to have the same volume in the merging chamber.

It would be nice to try a test though with a flow meter to see if that really is the case, or have someone with hydrodynamic experience tell us what they think.

 

[Aurabbit79er]

I posted the in the Gravity dredge Thread in the Gold prospecting Form.
Tell me what you think.

I did the raised suction pool type with 60' to sluice and SOMEONE STOLE MY PIPE!!!!
But it did work with about half the suction of a standard 4" dredge.
I though up a new type that uses a standard venturi.
When I can spend a $100.00 I'll put it together and shulp it up to San Gabriel EFR
Let me know your thoughts.



It is legal. I isn't drawn to scale.
And you can put pipes in each other for easy portage.

 

[ncclaymaker]

Having two pipes feeding will lower the water friction on the inside of the feed lines. Turbulence will remain the same, but two lines will help overcome the loss caused by the water turbulance. Would have been far lighter and easier to use just one larger hose instead.

 

[Hoser John]

Simply forget the jet and go sucking as no jet needed or dual hoses or nuttn-KISS -keep it simple and stupid and prosper-John

 

[Oakview2]

John your picture is hard to get a perspective of how steep the fall of the creek is, without giving out your location can you give some idea how steep it is... The picture makes it look very steep

 

[goldog]

Simply forget the jet and go sucking as no jet needed or dual hoses or nuttn-KISS -keep it simple and stupid and prosper-John

Would'nt the suction for that be poor? Moving material through the hose may be difficult. I've never really tried so I may be wrong.

AURabbit's diagram looks good. Either dual or single supply. Reasonably simple if you have a dredge available.

 

[Hoser John]

12' of drop over 40' of 4" dredge hose. To figure foot pounds= pi X the radius squared=per sq. in x 12 x 40 divide by cubic inches of water in a gallon of water PLUS the resultant mph with the inertia created by X weight at 45 degree angle for 40' =OUCH. MUCH more than any convalution trying to create inertia by slowing it down utilizing a jet is a bloody joke as using as many hoses as you want=simple grade school math-John

 

[Oakview2]

Thanks Hoser

 

[Hoser John]

EZ example= take a 5lb weight and pick it up---now take that same weight--raise it up a foot and drop it on your hand gravity and inertia are your friends as once you've slowed them down you've lost all that you seek with a restriction of a jet. Now consider 50-60 lbs of weight traveling at a high rate of speed slamming into ya and viola== OUCH .As with ALL mining KISS rules-keep it simple and stupid and prosper as convalution is NEVER the solution-John

 

[Gravel Hog]

Yep

 

[diverrick]

So why can't one simply roll out hose upstream until you have enough drop/pressure to run a normal dredge nozzle? I have seen other the suction stuff into the siphon hose, which makesno sense to me, especially if your useing the corrigated drain hose. I would think all your fines would get cought up inside the hose. Iam looking at a long suction hose that once primed, will have enough head pressure to run my nozzle. A half pound per foot, minus losses from friction loss. Got to find a nice section of river that has some good drop in a short section. Also wondered if a bigger inlet to "funnel" or capture the water better would help some.

 

[Jim in Idaho]

So why can't one simply roll out hose upstream until you have enough drop/pressure to run a normal dredge nozzle? I have seen other the suction stuff into the siphon hose, which makesno sense to me, especially if your useing the corrigated drain hose. I would think all your fines would get cought up inside the hose. Iam looking at a long suction hose that once primed, will have enough head pressure to run my nozzle. A half pound per foot, minus losses from friction loss. Got to find a nice section of river that has some good drop in a short section. Also wondered if a bigger inlet to "funnel" or capture the water better would help some.

If you assume your pump supplies water to the jet at 50psi, you'd have to have an elevation gain of 115' to get the same pressure using a hose. If the stream slope was 6'/100', you'd need 1,900' of hose to get 50psi.
Jim

 

[Hoser John]

2 of my great partners tried that with 2600' of hose, they spent a fortune but the drop still wasn't enough as must be pretty radical to get good suction. Never got that jet to work for squat but they bought smaller 2" hose so could not just straight suck(4" works great) as with a good gravity fall. You can go quite a ways and still have decent suction above the fall-John

 

[Jim in Idaho]

Probably the problem with that length of hose is volume. Obviously, you can get the pressure, but there's a lot of line loss in a 1/2 mile of hose. John, do you know how much pressure a typical pump on a dredge delivers to the power jet? Just curious.
Jim

 

[boogeyman]

12' of drop over 40' of 4" dredge hose. To figure foot pounds= pi X the radius squared=per sq. in x 12 x 40 divide by cubic inches of water in a gallon of water PLUS the resultant mph with the inertia created by X weight at 45 degree angle for 40' =OUCH. MUCH more than any convalution trying to create inertia by slowing it down utilizing a jet is a bloody joke as using as many hoses as you want=simple grade school math-John

"simple grade school math"? Do they even teach that any more? Or is that something the kids now days have to research in the lost arts section of the library?

 

[Bnugget]

I can personally say that johns method of just sucking works well, I used 170' of 6" schedule 40 pvc(Electrical conduit) duct taped together at the seams and was very impressed with the suction I got. The bell ends of the pipe allowed me to attach my 6" dredge hose and nozzle to the front end and dumped into a sluice at the other. The nice part was no noise!

 

[Goldwasher]

how much drop?