Header Box Angle

[Capt Nemo]

What's the best angle for the header box?

I'll be dealing with a non-adjustable box on my Model 5 fluid bed highbanker sluice, so I need to set the box correct the first time. 20 degrees seems a little too steep, and I'm thinking 15 would be better for washing the rocks more. I can cut the support pipes shorter but can't lengthen them once cut and glued. (PVC)

Adjustable would be nice, but the bed's plumbing makes that hard.

You Bazooka boys are going to freak once I get her done and post pics! (8 x 27" recirc bed)

 

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[DaleinTexas]

From what I understand there are several things to take into account.

First off have you ran it yet?
Are the rocks clean when they come out?

If answers are YES to both questions why change it?

Rocks not clean, how much water flow do you have?

You can decrease the angle of the header box get more wash time...


Another option I would suggest is to make your header angle adjustable because different places will have different soil types.

 

[Capt Nemo]

She's still under construction.

I mainly want to get an idea of what people are running and get an average from that.

Mostly she'll be running beach sands and gravels with the big gold at 50 mesh. The grizzly is built for 1/8" classification, but can change that to 1/4" if needed.

Here's the Model 4. You can see the problem with building an adjustable box. You have plumbing in the way! If I didn't run into problems with long axial piping, an adjustable box would be easy. Also the header box needs to be removed for cleanout, which would require readjustment of the box each time. Fixed is easier to deal with in this case.



Model 5 has about 3 times the volume of the Model 4, and could probably handle a 2 gal bucket all at once. Anything bigger is going to need a gas pump.

 

[Canuck]

Well for me it all depends on the material I'm running. When there's a bit of clay in the mix I like to decrease the angle to help break it down. Is there any possible way you can use flexible hose between the two? Sweet looking set up by the way. Im just in the process of finishing one up for the end of my highbanker.

 

[goldenIrishman]

As said before..... The type of materials you're running is going to be what determines the best angle. The 1/8 classification should be good for the materials you described but in reality that is going to depend on your water flow through the header box and the sluice itself. Go for the largest pump you can and if need be, you can throttle it back with valves. Better to have the flow and not need it than to need it and not have it. Also remember that the angle of the header box needs to be steep enough to allow for the tailings from it to clear out. When working on the setup on your fabrication bench it's going to look really steep because the sluice is laying flat. When the sluice is setup at the working angle the header box will flatten out by that working angle.

 

[Goodyguy]

I've found that adjustable works best. It will need to be steeper than you imagine if the gravels are flat vs rounded.
This is not quite a highbanker but the same principal applies.



This is my super fluidbed bank run 3" dredge. At times I've had to run the header as much as 45-60 degrees to keep the grizzly clear.

 

[Capt Nemo]

That's an awesome fluid bed dredge Goodyguy!

 

[Capt Nemo]

Just did a test with some of the gravel that I'll be running. I ran wet gravel through the header with no additional water to see what would stick or hang up at 15 degrees.

The big stuff (3/4 - 1") pretty much fell straight through probably a bit too fast. The little stuff (<1/8 - <3/4") either stuck to the UHMW PE, went through the grizzly, or was rejected off the end. The saw cut UHMW grizzly will have a lot of vibration and flex to let some bigger material through, so a gold nugget bigger than 1/8" will probably have enough weight to fall through. On site, I'll use a catch bucket to see if there's any gold that's rejected over the grizzly. (There might be some big stuff hiding in the gravel at the shoreline.)

I feel safe that once the spraybar is operating I can drop the angle to 10 degrees and it'll run just fine at 800 GPH. In the pic, the ruler is 6" long.