Show off yer sluice

I use expanded in my big sluice.

My finishing sluice is stock, except for the magnet:



image-2438331252.jpg
 

KevinInColorado said:
ive seen formal studies showing that orientation of expanded metal doesn't matter at all!
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KevinInColorado said:
Well, I saw it on nan other thread here in tnet...just a few days ago. I don't use expanded of any sort in my sluices so I'm no expert.
Click to expand...

I'm confused... Are you saying that you saw the formal study posted on another thread in T-net or that you only read a post that someone else had seen the study.
Not trying to nail you just looking for clarification.
 

Goodyguy said:
I'm confused... Are you saying that you saw the formal study posted on another thread in T-net or that you only read a post that someone else had seen the study. Not trying to nail you just looking for clarification.
Click to expand...
pretty sure a link or quote from the study was posted but I didn't pay enough attention since I don't use expanded myself. Just made note of it since it is interesting academically to me being an engineer by training. Sorry but a tnet search might help...
 

Just saw the comments about my expanded possibly being in backwards... Coulda been! Remember I'm still green! :-) maybe that's why I caught less gold last time at the same spot?, that or I veered from the pay streak... Probably got to deep in flood gold
 

I have seen many references to a study by the university of British Columbia. These posts on other forums talk about direction of expanded metal not being important.
I did a search and found the report. It is 50+ pages and full of useful information including the effectiveness of expanded metal to recover -1 mm gold. Due to the length of the study I skimmed most of it and focused on conclusions. Nowhere did I find anything about the effectiveness of direction changes. It may be there but I didn't see it. This may be an urban legend. I don't know if this is the study or not, only what I found.
 

drywallman said:
Just saw the comments about my expanded possibly being in backwards... Coulda been! Remember I'm still green! :-) maybe that's why I caught less gold last time at the same spot?, that or I veered from the pay streak... Probably got to deep in flood gold
Click to expand...

I always run mine with the high points in the upstream direction.
 

100_0257.JPG

100_0656.JPG

Nothin' fancy, but seems to work.

As far as expanded metal direction, I always put the low side upstream, it makes a little ramp (riffle), and collects the heavies below.

Wouldn't the other direction just pack tight with material, and let the good stuff slide over?
 

What happens in theory is a vortex is created ( a horizontal swirl) of material and water. Just like a riffle, it exchanges the lighter material out retaining the heaver material. So the debate goes on.
 

It is referred to as the Clarkson study and in the report he tested expanded both ways and saw no difference. It was a study on Yukon placer mining and setups that would work the best for their material. It is a great report and a must read if you would like to understand how the sluice and riffle choices work.
 

It does matter. In a sluice with Hungarian or no riffles. Raised expanded exchanges material when the higher side is up stream making a riffle and vortex. If the high side is downstream material packs in and doesn't exchange properly. The Clarkson study is a study mainly on riffle type, spacing and angle. And the size of the tests in the Clarkson study is irrelevant to stream sluices. A wash plant running a Clarkson riffle sluice has its riffles so close together that expanded is pointless and the material is driven down into the matt and not across it like in a traditional sluice with Hungarian riffles. If you live in Indiana and are running a sluice box with raised expanded over carpet or moss or whatever..... no riffles and you are classifying. And you add material and the expanded is " backwards" more light material is going to pack in because it isn't exchanging properly. Another thing to think about. Drop riffle sluices.... notice how much closer the riffles/traps are together....same principal as the Clarkson riffle design....works great. Great exchange at high flow...if you could turn it " Backwards" would it still catch gold? Yes. would the traps pack up and not exchange properly? Yes. Will you lose fine gold that is not making it to the bottom of the slurry and has no where to settle? Yes. Regular expanded has no relevant "Direction" Raised does for sure. Most importantly are you digging good material....and is it getting the proper chance to stratify and settle into the low pressure traps. Skimming over studies... may lead to gold skimming over your riffles and back into the stream.
 

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Goldwasher said:
It does matter. In a sluice with Hungarian or no riffles. Raised expanded exchanges material when the higher side is up stream making a riffle and vortex. If the high side is downstream material packs in and doesn't exchange properly. The Clarkson study is a study mainly on riffle type, spacing and angle. And the size of the tests in the Clarkson study is irrelevant to stream sluices. A wash plant running a Clarkson riffle sluice has its riffles so close together that expanded is pointless and the material is driven down into the matt and not across it like in a traditional sluice with Hungarian riffles. If you live in Indiana and are running a sluice box with raised expanded over carpet or moss or whatever..... no riffles and you are classifying. And you add material and the expanded is " backwards" more light material is going to pack in because it isn't exchanging properly. Another thing to think about. Drop riffle sluices.... notice how much closer the riffles/traps are together....same principal as the Clarkson riffle design....works great. Great exchange at high flow...if you could turn it " Backwards" would it still catch gold? Yes. would the traps pack up and not exchange properly? Yes. Will you lose fine gold that is not making it to the bottom of the slurry and has no where to settle? Yes. Regular expanded has no relevant "Direction" Raised does for sure. Most importantly are you digging goog material....and is it getting the proper chance to stratify and settle into the low pressure traps. Skimming over studies... may lead to gold skimming over your riffles and back into the stream.
Click to expand...


Ok, let's get this straight. You say high side up stream.....maybe it's just our upstream downstream terms that are confusing.

Here is a diagram, It's not raised expanded metal, but it shows the basic shape, with a small ramp...high side down stream as I would call it. Are you saying this is backwards? High side should be upstream? :icon_scratch:

images.jpg
 

afreakofnature said:
It is referred to as the Clarkson study and in the report he tested expanded both ways and saw no difference. It was a study on Yukon placer mining and setups that would work the best for their material. It is a great report and a must read if you would like to understand how the sluice and riffle choices work.
Click to expand...

Please show me where that is found in the 1989 Clarkson study. I see no mention of running the raised expanded both directions.
In fact the only pictured example showing the raised expanded metal has it pointed the same way as a traditional riffle.

The-Clarkson-Study-Fine-Gold-Recovery

22-8ceb2c4003.jpg






NOTE:
* In the conclusions to the study entitled: "Fine Gold Recovery of Selected Sluice Box Configurations" conducted at The University of Columbia by Prof. G.W. Polling. Authored by James Hamilton and Published in 1988 (published prior to the Clarkson study)

It was stated: "The orientation of expanded metal riffles is not important to gold recovery"
*There is no reference contained in the study as to how that conclusion was arrived at or any data supporting that claim!
Also Just wondering if the word "RAISED" was accidentally omitted or if it is just understood (perhaps raised was all that was being produced at the time of the study)

Below is a link to the Polling study...
Fine Gold recovery of selected sluice Box Configurations


My advice is to thoroughly read the complete studies to avoid any misconception from reading a finding out of context and jumping to an ill-informed conclusion. (The Polling study was performed on only one sluice indoors under controlled conditions)

Go for the gold
GG~
 

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In your diagram the flow is coming from the right , the "upstream" as in where the water is entering the sluice. That is the side the high side of the expanded should be on. To create a little vortex trap. Just like the trap shown in your diagram. I think the confusion is about what the "high " side of raised expanded metal is?
Gold Maven said:
Ok, let's get this straight. You say high side up stream.....maybe it's just our upstream downstream terms that are confusing.

Here is a diagram, It's not raised expanded metal, but it shows the basic shape, with a small ramp...high side down stream as I would call it. Are you saying this is backwards? High side should be upstream? :icon_scratch:

View attachment 935647
Click to expand...
 

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Goldwasher said:
In your diagram the flow is coming from the right , the "upstream" as in where the water is entering the sluice. That is the side the high side of the expanded should be on. To create a little vortex trap. Just like the trap shown in your diagram. I think the confusion is about what the "high " side of raised expanded metal is?
Click to expand...


There are many different and varied styles of raised expanded metal on the market today. But the most commonly used in sluices is this type
#1 shows the raised going against the flow while #2 shows it going with the flow.




#1---------------------> flow
expmtl-2-angled_small_38.jpg


right.jpg
#2-------------------------> flow

Conventional wisdom would recommend #2

However, due to the unusually shaped well that is created by the diamond shaped pocket I suppose that a unique turbulence could be created that may cause a disruption to the normally expected low pressure area behind the high edge of each diamond causing an anomaly......
Naw...... #2 is the way to go :icon_thumleft:

One thing that all the studies do agree upon, is that maintaining the proper flow and feed rate is essential for the expanded metal to scour/exchange efficiently.


GG~
 

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I've had people confuse me before on that as well and if you look at an individual diamond shape in the raised expanded one side will be tilted up and one side down, I run mine with the high side towards up stream with the water hitting the high side first when its coming into the sluice. It might work facing the other way but doesn't seem like it would exchange as well and it sure wouldn't hold as much material of which there's not a lot of space anyway in the expanded that came in my keene sluice. Yep goodyguy has is right with pics even and the #2 pic is how I run mine, which should give more exchange and more room to hold the heavy materials without washing out as easy.
 

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