Drop Riffle Sluice / Angus MacKirk - capturing fine (flour) gold

[X4FRNT]

I have two drop riffle sluices, a Angus MacKirk and a Robinson’s Brothers drop riffle sluice. They work great for capturing the larger gold flakes, but the flour and fine gold I find in my test pans are not being caught in either of my sluices.

I run the sluices with proper water flow and angled correctly and run classified material to 1/4”. After watching doc’s vid on Proportional Force multiple times I feel as though the fine gold doesn’t fall out into the drop riffles because the lack of disturbance/disruptions when using a drop riffle sluice. Angle and water flow play into this problem, lack of either means that it takes longer to clean the riffles and less material can be run through the sluice. Just wondering if anyone else is having similar issues, or if anyone has any advice on how to capture the fines from that upper water column.

I’ve been thinking of running the Robinson Sluice paired with the Angus behind it, and adding a damper before the material enters the Angus sluice. This would force the fine gold down into the lower water column and give it a chance to drop into the riffles. I’ll give it a try at least.

Thoughts?

 

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[RTR]

Love my MacKirk(for what it is) If you want to capture (flour) gold your better of getting a miller table.

 

[KevinInColorado]

I’ve been running an AM Expedition for years. Several options:
1. Run the sluice with less water depth.
2. Classify to 8 mesh and run with less pitch& flow
3. Both 1&2
The sluice is capable if run for the conditions you face.

 

[RTR]

One way to find out if the Angus is leaving fine gold behind. After you are all done running the material Place the material





into a pan with a few drops of liquid dish soap or Jet dry (used in dishwashers). This will break the surface tension of the water ,keeping fine (minus 100 mesh gold in the pan) from washing away.

 

[Duckshot]

I have used a home built wooden drop riffle sluice to catch a bit of gold dust in WI. The thing is I have exactly no idea how much gold I might have lost, but I'm sure it isn't catching every grain. The only way to see exactly how much a sluice loses is to pan out everthing you originally ran through it. But, how do you know you are catching everthing in your panning?

Sluice it all again and pan it again?

It ain't a bad idea to test your tailings, but at a certain point you are better off just running fresh dirt.

 

[Lefty2u]

I have a large Mad Miner's sluice that I have removed the riffles out of. I have a 17 inch flare followed by 10 inches of inspection mat. This is followed by 17
inches of deep V mat. Next there is 6 inches of mother load mat. This is working very well on fine gold. I screen to 1/4 inch. I got help, information, from
John Doe. I am working a spot with only fine flood gold. Take a look at John Doe's posts.

Lefty2u

 

[Oregon Viking]

Gold Hog mats.

 

[X4FRNT]

I’m thinking of building a fluid bed sluice to run behind my drop riffle, that way I can still run 1/4” material at a good pace and have the fluid bed capture the fines that are still trapped in the water current. Picked up the materials to make it yesterday at Lowe’s and plan on building it this evening. Worth a try I suppose.

 

[arizau]

I have two drop riffle sluices, a Angus MacKirk and a Robinson’s Brothers drop riffle sluice. They work great for capturing the larger gold flakes, but the flour and fine gold I find in my test pans are not being caught in either of my sluices.

I run the sluices with proper water flow and angled correctly and run classified material to 1/4”. After watching doc’s vid on Proportional Force multiple times I feel as though the fine gold doesn’t fall out into the drop riffles because the lack of disturbance/disruptions when using a drop riffle sluice. Angle and water flow play into this problem, lack of either means that it takes longer to clean the riffles and less material can be run through the sluice. Just wondering if anyone else is having similar issues, or if anyone has any advice on how to capture the fines from that upper water column.

I’ve been thinking of running the Robinson Sluice paired with the Angus behind it, and adding a damper before the material enters the Angus sluice. This would force the fine gold down into the lower water column and give it a chance to drop into the riffles. I’ll give it a try at least.

Thoughts?

To me it seems like not catching the fine gold is evidence that the riffles are packing up and not constantly "dancing" or exchanging. Not only can that cause you to lose fine gold but some of the larger particles too since they cannot penetrate the capture areas and are just swept across the top of them and out of the sluice. Swifter current and or steeper angle on the sluce may remedy this. Have you seen the videos here? https://www.google.com/search?q=ang...j46j69i60l2.5894j1j7&sourceid=chrome&ie=UTF-8. A couple of those show pretty extreme flow. I would say, run it flat in swift current and steepen it in slower flows.

Good luck.

 

[Gold4Mike]

I've got an Angus Mackirk and it catches very fine gold. It can be a little difficult to run one sluice behind another, but you can sure test the losses of either one of your sluices by running the other right off the first. It would be an interesting test of either one.

 

[Goldwasher]

if the first sluice doesn't catch fine gold.. it isn't gonna get caught in second sluice.

No matter what type the second is.

The best bet for getting more gold in your sluice. Is to run dirt that has more gold in it.

 

[KevinInColorado]

if the first sluice doesn't catch fine gold.. it isn't gonna get caught in second sluice.

No matter what type the second is.

The best bet for getting more gold in your sluice. Is to run dirt that has more gold in it.

Often true.
Unless the first sluice sucks or is set up poorly. I once put a fluid bed below a friend’s WolfTrap Hungarian riffle sluice and it was amazing how much gold I caught. The friend was just horrified lol!

 

[Goldwasher]

Often true.
Unless the first sluice sucks or is set up poorly. I once put a fluid bed below a friend’s WolfTrap Hungarian riffle sluice and it was amazing how much gold I caught. The friend was just horrified lol!

True if the first sluice isn't good hopefully the second will catch some. I guess what i'm getting at is if the first one is working right the second isn't gonna kick in on what isn't held by the first.

I was mainly referring to the fine gold that is at the lower end of the catch rate anyways.. That if water speed has kept it moving... is very unlikely to drop out of suspension.

 

[Johnnybravo300]

It's like tossing fish back that are too small. Letem grow a little more!

 

[X4FRNT]

It's like tossing fish back that are too small. Letem grow a little more!

😂 that’s how I’ll view it from now on. (If only it worked that way).

 

[mytimetoshine]

I have no problem catching dust with my Angus Mackirk drop riffle.... In fact it has the best recovery imo, but you have to have proper exchange going. It's not about water speed and angles. If the material exchanges properly then it will catch. if it's getting packed up then it will blow gold all over the place

 

[arizau]

Check this drop riffle design out. Note that he has it set up in a switchback design as a highbanker.

 

[Duckshot]

Check this drop riffle design out. Note that he has it set up in a switchback design as a highbanker.

That first drop down ain't catching nothing. The material does not appear to have been classified, he's sending it down in clumps. I didn't even watch the whole thing.

ETA- it's not a bad design for a sluice, but it needs adjustment IMO.

 

[Goodyguy]

That first drop down ain't catching nothing. The material does not appear to have been classified, he's sending it down in clumps. I didn't even watch the whole thing.

ETA- it's not a bad design for a sluice, but it needs adjustment IMO.

That first tray seems to be doing a good job of stratifying material for the next 3 runs, similar to what the top tray on a gold cube does.
Would be interesting to see just how much gold is being captured in the first run if any.

GG~

 

[Duckshot]

I see what you are saying. But there has to be better ways to break stuff up than flat boarding it over deep drop riffles. In my favorite home built drop riffle the first 8" or so are 1/4", 1/8" deep dados spaced 1/4" apart. Imo it pays to have a drop riffle with a couple different shaped riffles. The plastic drop riffles that are just three feet of the same sized riffles never made much sense to me. If my sluice can't catch gold going past in a foot worth of riffles, I want to try different riffles.