ICEBREAKER!

[Joe S (AK)]

OK, enough of the 'ole "I just don't have time to post" thinking. Lets try this one on -------

What kind of riffles/catchments do you use in your box and why do you use what you do?

For me - it's usually Gold Hog mats. The various "riffle" shapes really do well for where I work, which is usually just south of Denali Park in the Cache Creek / Petersville area.

A fair amount of clay in a glacial setting means that the gravels do, sometimes reluctantly, wash clean and with a range of very small Gold sizes the capture is really good.

How about the rest of you?

Joe

[Slatco]

I use 1.5" angle with miners moss set at angles based on Clarkson study for the top three feet of my box on a 36 wide sluice, the rest is expanded metal. Clean up every 3 hrs so overloading is not a issue. I use this setup as my gold is flaky and flat. I believe the larger riffle profile of the angle iron prevents the flake from skating along on top like they do on the lower expanded. I have seen them skip down my vortex riffles and letrap like a surfboard.

[Joe S (AK)]

Hey There Slatco!

Just what I thought - "Different Horses for Different Courses".

It would seem to me that the riffle side profile (with the traditional 17 degree up turn?) would give the slurry flow a rise, and then a dip down between riffles - resulting in some scouring of the lighter materials down into the expanded or moss and from that action allowing the loose (or previously captured) Gold to work it's way down into the, more protected (by expanded lath or the quieter inter Moss weave) lower areas.

The only difficulty I foresee would be the nearly identical set of forces with each riffle - meaning that if not caught in the first couple of riffles there might be no variation in any of the rest to catch Gold pieces with different dynamics.

Have you checked progressive segments of your riffle run to determine where the flat Gold is actually being retained? If only in the first few riffles then some sort of variation in capture zones MIGHT increase Gold retention further down the run by catching some of those "runners".

One of those "I wonder if .....?" things, I guess.

Joe

[Jim_Alaska]

Good topic Joe. Mine is on my dredge because my hands do not fit a D handle shovel. I am using the original set up that that Dave Mack designed It consists of four Hungarian riffles as nugget traps at the head. Then everything goes over a raised screen that classifies out cobbles and allows gold bearing material through. This material then goes over something I cannot remember the name of. It is a thin, flat steel sheet with alternating spaced eyebrow riffles. The only modification I made was to insert miners moss under the steel sheet to replace the traditional carpet that Dave originally had.

Funny, I have the name of that kind of riffle in my mind, but just can't seem to get it out!

Suffice to say that i works extremely well and I don't know why it never caught on for conventional sluices. It probably has to do with the necessity of a screen to allow cobbles to bypass and the rest to drop down.

[Joe S (AK)]

Sunscreen is what I have heard it called.

[Jim_Alaska]

That is not the name of it Joe. It will come to me one day in the distant future.

[Beav]

Hey Jim, are you thinking of ARMOURWEAVE?
I just sold an old original Pro-Mack sluice that had that in it exactly as you described.
Plus I have been following Dave since the early 90's too and am very familiar with his gear !

Beav

[Jim_Alaska]

Yes beav, it is Armourweave. I remembered it last night after I was in bed and couldn't post until this morning. Thanks for the nudge though, appreciate it.

As I said in my reply to Joe, my application for recovery is on a dredge, so the application would be useless in a shovel in operation and especially with the clay he mentioned.

[Joe S (AK)]

Yes, I have seen photos of that style of expanded and know that it came very highly recommended.

As I remember it, the problem was availability at the time - so, possibly that has changed since then.

As to a shovel-in highbanker or river sluice not being optimum for it's use - possibly a smaller sized mesh would do better in their reduced flow dynamics.

Joe

[Jim_Alaska]

I am not sure how a smaller size mesh would help in breaking up clay. I have had places where I actually got into clay in the river with this configuration. Even the size mesh that comes with the dredge got clogged badly with the clay, which allowed material to run right over the top of the clay and mesh without ever falling through to the ArmourWeave.. Of course this is the newer dredge configuration that does not use a "crash box" header. In the newer models the jet flare makes a rather smooth transition form flare to sluice box, whereas the crash box tended to break up clay type material.

Perhaps for a shovel in operation like your's with the gold cube, there would be lots for opportunity to break up clay due to the violence in the top of the cube, this might allow the ArmourWeave to work. In my dredge configuration the actual ArmourWeave works extremely well with no testable loss of even very fine gold.

I had a couple of experiences dredging other people's tailings and recovered gold they missed.