Subsurface dredge sluice setup

[Quinc]

just about done with the box. Just need to make a screen for her. Screen is going to be 6.25" wide by 10" long. Thinking about one of the below. Something with 1/4" - 3/8" holes/slots in it.

Leaning toward this one with the slots. Any opinions?

Thinking this style might have issues with shell getting stuck. (bbq grill)

 

[russau]

Slots will let in larger pieces and I don't think you want that ! I used 14 inch Stainless steel punch plate on mine and let the riffles stop the bigger pieces up in your sluice area.

 

[Quinc]

Everything is still loose so I can adjust the spraying as needed. Here is a pick of it standing upright so you can see the spray. Second pick is of it sitting level:

Looks like its agitating enough while sitting level?

Mock up mostly put together: Punch plate is .37" holes. They look a bit big but its what I have for now. angle on the corners to make her stronger and the corners/gaps filled in with silicon.

 

[N-Lionberger]

Does the screen ramp up or is it angle of the picture?

 

[Quinc]

Does the screen ramp up or is it angle of the picture

It ramps up. I have multiple holes drilled so I can change the angle while testing.

 

[Quinc]

Ran her today for an hour. Lots of rocks would build up on the screen. I think raising the first part of the screen to be level with the main sluice will help. Maybe drop or remove the angle as well? After an hour There was maybe an 8th of a pan worth of material. Not even up to the pvc pipe. Not sure if that is good or if I have too many holes spraying? Not a great day when it comes to gold I didn't find much with or without the fluid bed. But I did find more then I would have liked in the fluid bed! Video of it in action. Picture of the gold at the end is only from the fluid bed. Probably 3x that amount in the main sluice.

 

[N-Lionberger]

I was wondering if that angle of of the screen would hang up rocks. You seem to have a lot of nice shallow bedrock there it might be more worth it for you to get like a small surface dredge to clean that bedrock. I’m looking at my 6” subbie as my spot the gold bearing hard pack is under around 4 feet of loose cobbles.

 

[Quinc]

I was wondering if that angle of of the screen would hang up rocks. You seem to have a lot of nice shallow bedrock there it might be more worth it for you to get like a small surface dredge to clean that bedrock. I’m looking at my 6” subbie as my spot the gold bearing hard pack is under around 4 feet of loose cobbles.

I started shallow and worked my way down. As it gets deeper it turns into a red/gray cement of gravel and clay. Have to use a high pressure hose to break it apart. Now that it is getting warm I will be switching over to my Proline surface 4" with air.

 

[N-Lionberger]

I started shallow and worked my way down. As it gets deeper it turns into a red/gray cement of gravel and clay. Have to use a high pressure hose to break it apart. Now that it is getting warm I will be switching over to my Proline surface 4" with air.

Yup similar material here cemented red stuff. Gotta have that blaster hose you ain’t really dredging without one! I’d be using my 5” Keene this year but the winter did a number on it so it’s back to my 4” frankendredge and the 6” subbie. I’ve got a 2.5”X2” DK Nugget dredge pump on a 6.5hp Honda with a Gast compressor and water heater with a dual fuel carb for gas or propane with a 4” Vortxrex jet

 

[russau]

In your video it appears you have the water pressure (as is ) running way to fast . To me , you need more capture area with the water pressure that high BUT If you lowered the water pressure at the pump you would kill the suction that you need ! If it were mine, I'd add wider and a longer capture area and leave the water pressure alone.

 

[Quinc]

Screen is now going to butt up against the main sluice in the dredge. and the angle is significantly reduced. Next on the list is to fill it up with black sands hook it up to the garden hose and adjust to see the best pressure for the jets.

 

[Quinc]

Took the subby out this weekend and ran it on some good gold with the fluid bed. The screen angle is working perfect with no rocks jamming or getting stuck. @russau I took you suggestion and added a way to adjust the flow so it wouldn't so fast this time around and had a lot more cons in the fluid bed. =)

I panned the sluice box separate from the fluid bed every 2hrs. I tried running more rpms and less rpms and it didn't seem to make a difference on the recovery of the sluice vs fluid bed. Every clean out ended up being around 20-30% of the gold in the fluid bed. Too my surprise the gold being caught by the fluid bed was large flakes and fines. Even got a full size square nail in the fluid bed. So if you think you arent loosing any "big" gold out of the sluice.. You are. Next time out I will try doing a clean out every 1hr and seeing if it makes a difference. The next thing is to try and figure out how much gold I am losing out of the fluid bed.

 

[N-Lionberger]

Honestly I never had the thought the subsurface dredge tube would catch even the bigger gold. The little box in there I’m amazed you’re catching the gold you are getting. I always had the thought of using mine as a method of removing overburden from where I want to run a smaller surface dredge.

 

[Quinc]

Running the Subby this pass weekend I was finding mostly smaller gold in both the sluice and fluid bed. Got to thinking about how I could run a classifier screen the whole length of the tube. Has anyone seen this done before? Please enjoy this amazing rendering I did in mspaint.

 

[Quinc]

Look what I found! The 5" subby Sluice is the little one for comparison. How much pump do y'all think will be needed to run this behemoth? Pressure tube on the nozzle goes from 3" to 1.25 inch.

 

[russau]

Nice find ! I'm under the impression that a 5 HP engine with a 300 / 350 GPM pump would work! Similar for a 4 inch dredge BUT since it is a under water device , you could use this combination . This would be the minimum size for shallower water ! A Pro-line P400 pump would be better !

 

[Quinc]

Nice find ! I'm under the impression that a 5 HP engine with a 300 / 350 GPM pump would work! Similar for a 4 inch dredge BUT since it is a under water device , you could use this combination . This would be the minimum size for shallower water ! A Pro-line P400 pump would be better !

You ever play with running pumps at higher rpm or with more HP? For instance if the hp300 runs with 5.5hp and 3200rpms, would it make anymore psi or gpm at 6.5hp and 4000rpms? Or is the limiting factor the pump itself?

 

[russau]

I only ran my engine /pump at 75% of it's RPM. More HP don't come into play unless your going deep or a long suction tube . I preferred using 10 foot sections of my suction tube and add of if I want to reach out further and I didn't like doing that !

 

[Flatline]

You ever play with running pumps at higher rpm or with more HP? For instance if the hp300 runs with 5.5hp and 3200rpms, would it make anymore psi or gpm at 6.5hp and 4000rpms? Or is the limiting factor the pump itself?

From my eeeeeeextensive chats with chat gpt.. no not really, it only really matters if you are going deeper, then hp comes into play as it will be easier for the engine to maintain the rpm etc.

 

[Quinc]

Picture found on FB: