Gravity Gold Dredge

Gravity dredge testing.

http://goldfever.com/g_dredge.htm

http://www.geocities.com/r0n314/

http://www.youtube.com/watch?v=Zn0vOPiUqDE

http://www.youtube.com/watch?v=-7N-ubzStDE&feature=channel_page

http://www.southernprospectors.com/id21.html

Category:

Education

Tags:

• Gold prospecting
• sampling
• panning
• gold trap
• bedrock
• sluice
• crash box
• mining.

[starflash08]

hey exanchorite, good work but little confusing, some gravity dredges trap pay dirt in there ribbing along the 100 ft or so of pipe, but clean up is a problem, with your suction nossel do you need another short section of pipe to a sluice box close to where you are working?, post another effort all connected up, im sure youve developed a far better gravity dredge not obvious to us less imaginative persons, the gravity dredge is all about getting out into nature and enjoying the piece and quite.

[exanchorite]

Thanks Star,

Yes another section of hose attached to a sluice box. You can start at the top with a larger diameter hose and get more suction or just get more hose and a taller drop. I gave my hose away when I moved to AK. Most likely won't be testing this idea further since I'm making an ice diving dredge right now.

-Kevin

[starflash08]

@exanchorite i know im a bit thick but if the hose to the sluice is separate to the long hose providing the fall and suction, how does the short hose suck up the gravels, vortex?, cheers david

[exanchorite]

They call it a Venturi effect. The whole concept of a gravity dredge came to me from the old timers hydraulicing. Google hydraulicing. The basic idea is to take a large volume of water in conjunction with gravity and reduce the size of the pipe the water travels in as you get lower in elevation. Gravity creates a certain amount of pressure as the weight of the water in the pipe above has nowhere to go but down. The reduction in pipe size from large to small creates a "venturi effect".

[exanchorite]

Google venturi effect. When you reduce the size of the pipe the pressure does not increase or stay the same, the pressure decreases, but the velocity (speed) of the water increases. The speed of the water is what creates the suction. In my case I used just one size hose to see what gravity could do on its own. I reduced it down from 2" to 1" with a suction nozzle. I got mediocre results.

[exanchorite]

If I had the same amount of fall and hose length, but I started with a 4" pipe and reduced down to a 2" pipe and then down to my 1" suction nozzle the velocity of the water would be even faster and the suction would be even greater. Because of the venturi effect 4” of water reduced to 2” equals increased velocity and 2" down to 1" increases velocity again which will increase suction on a jet log or suction nozzle.

[Woodchuckk]

@ucamper08

Itsn't in a ban on all suction dredging? Or just gas powered dredging?

[maxinpains]

hope he can make gas money.

[ucamper08]

I have thought about this alot and with enough tube u could gvet around the dredging laws!great vidieo

[exanchorite]

The pressure is reduced as you go from 4" to 2", but the speed is increased.