Separation of laminar flow patterns

[Goldtarget]

Fairly broad question and I'm happy to clarify but has anyone attempted or succeeded in separating laminar flow patterns without using the vortex method? Its hard without a picture to explain what I'm proposing but I'll attempt to explain....was thinking a ramp type setup which allows an underflow for the heavies that then proceeds to a vortex for separation, while the upper and mid level are repelled over the top. The obvious flaw I see in this is the flow pattern underneath assumes its original pattern but with gold likely being the heaviest part of the material i would theorise it would still separate. This ramp would obviously be just after the slick plate, any thoughts? I'll test it anyway regardless, just trying to think outside the square of separation of flows as a whole body, in an attempt to process the lower level on its own so to speak.

 

[TenOunce Tone]

Sounds similar to what a "pinched sluice" does and what one of the "bazooka" style sluice does. I am assuming this will be either operating under a trommel or as a highbanker type setup. Interesting project..

Cheers, Tone

 

[Goldtarget]

Small highbanker. I looked into the pinched sluice concept after you posted, very interesting I think its good to approach things from different angles, I'm using the same concept in a slightly different mechanism in an attempt to achieve some variation on velocity and flow increases. More of a vertical"funnelling" effect rather than a horizontal pinch though from the top to bottom box, from there the desire is to get the flow to then spread again not really a capture feature, more of an increase in velocity without increasing the flow and levelling out surging due to the material being added. I've come to the conclusion that these surges have an effect on displacing settled gold and heavies and whilst i can't eliminate them without automation, i can reduce their size and impact. If you think about a river with high flow vs low flow i think that best illustrates what I'm referring to.

 

[TenOunce Tone]

Hmm maybe go for a wider bottom and a more concentrated input for the water, put a couple of baffles (im thinking like a tin can cut length wise in half ) to create a chock point, this should cause the water level to increase and cause some of the water to flow back, my theory is that the water that gets deeper will have fast bottom and slower top. the back flow up the sides will cause friction and slow the speed down at the start... just a crazy theory based on my interpretation of what you have written.. I would think the whole thing would be about 4 or 5 feet long or longer and about 12 - 15 inches wide.. with the pinch about 8 inches across, similar to a mckirk sluice in shape but with a flat bottom...

I am sure there are people on this forum who understand fluid dynamics better than I.

still, an interesting project..

Cheers, Tone

 

[Goldtarget]

You raise another point....the dimensions you have described. I wonder what the general thoughts are on dimension, I'm beginning to think that wider does not translate to better. I catch more in a 200mm at twice the length of my 400mm. I have a soft spot for the larger one due to its ability to process more material than i can put in in, but seem to pan out more colours in the little one. I must confess i haven't tested them side by side. I appreciate your suggestion thanks again. With any luck I'll get to test the separation theory in the morning in the field, the backyard results are encouraging. Im open to crazy theories, more often than not there can be some real merit in them. Worst case scenario it fails with a need to come up with something else.

 

[Barra_Mad]

This is something you could debate all night, but from discussions I have had in my extractive metallurgy class there are a few basic principles to take into account, so you can make sure you don't end up with a laminar flow that is not disrupted by the vortex created by by your riffle.

1. the height of the vortex created by your riffle should extend from the top of the riffle to surface of the water. If the surface of the water is not being disturbed you are loosing gold, but on the flip side if you water is to shallow you are loosing gold!
2. the water flow should be fast enough to move the largest particle entering your sluice.
3. the size of your gold traps and riffles should be larger than the largest particle entering your sluice.

I plan to make a video comparing different styles soon just need so free time. But the best method for you to look at will be the sloping expanded metal screens over miners moss, this seams to be the gold standard when it come to sluicing. Hope that helps mate.

 

[Goldtarget]

Seems to me i missed some good discussions. Your points are well made. In the end that is the beauty of the forum, it can be continually added to. Thankyou. Would love to see the vid when its done.