Counter Flow Sluice?

[Geowizard]

Hi Guys and Gals,

I introduced the concept of a Counter Flow Sluice on the Remote Prospecting thread and decided to create another thread to discuss this revolutionary idea.

You have probably heard the phrase; Necessity is the Mother of Invention!

I am surrounded by an extraordinary amount of fine (20 mesh minus) GOLD. The necessity has been HOW to design a process to recover small GOLD that exists in very small quantities in millions of cubic yards of dragline tailing piles.

After years of frustration, increasing capacity, increasing flow, increasing volume - all of which are inefficient in catching small GOLD, I came up with a counter intuitive solution that I would like to SHARE right here on the ALASKA GOLD PROSPECTING FORUM!

Stick around and find out more about this new, revolutionary, concept!

- Geowizard

[Geowizard]

Time is of the essence;

Let us assume there is a Remote mine somewhere in the interior of Alaska that has an almost unlimited amount of dragline tailing piles. Those tailing piles have been partially mined and the tenor of the GOLD in them has been on average 300 milligrams per cubic yard.

A rational approach to mining tailing piles includes a loader, wash plant mining scenario. The number and size of loaders and wash plants can be "scaled" to satisfy the desired rate of production. The settling TIME of small GOLD becomes the ultimate LIMIT in what the rate of production is in a given wash plant.

IF you push the GOLD through the wash plant BEFORE it settles, it goes out the end!

The DESIGN of the the Wash plant must meet a radical although NOT NEW method of catching GOLD.

The FIRST step is increasing the ANGLE of the sluice box AND establishing TWO or more vertical levels having different FLOW rates.

Stick around and find out HOW!

- Geowizard

[Geowizard]

Jacked up sluice;

Gravity is an amazing force! It is free and we are surrounded by it. Gravity is also an "accelerating" force!

Contemporary thinking in recovery of SMALL GOLD using GRAVITY in a sluice box has been to REDUCE the ANGLE of the sluice box and REDUCE the flow. All of this plus the effort of classification by screening requires time and increases the "front end" of the recovery process. The complexity of monitoring flow rate allowing for settling of GOLD over a longer than usual sluice box adds to the variability of recovery and the overall capacity to recover large volumes of GOLD.

High Capacity Recovery;

In a high capacity system, either the system gets LARGER or the system gets more ROBUST.

Increasing the ANGLE of the sluice has the advantage of increasing FLOW. In the case of a sluice having minimal or NO screening as seen in a SUCTION DREDGE, velocity is obtained and maintained continuously by the force of the water jet as the suction dredge operates. Over-size gravel, rocks, etc. flow over and OUT of the sluice. In the case of a HIGH BANKER, a JACKED UP SLUICE provides the needed FORCE to roll over-sized gravel and rock, etc. out the end of the sluice!

Where does the GOLD go?

Stick around and find out!

- Geowizard

[Joe S (AK)]

I disagree with this portion:
"Contemporary thinking in recovery of SMALL GOLD using GRAVITY in a sluice box has been to REDUCE the ANGLE of the sluice box and REDUCE the flow. All of this plus the effort of classification by screening requires time and increases the "front end" of the recovery process. The complexity of monitoring flow rate allowing for settling of GOLD over a longer than usual sluice box adds to the variability of recovery and the overall capacity to recover large volumes of GOLD."

That type of dated thinking, that this premise promotes, went out with wooden riffles, burlap and other common / new thoughts in those simple to make Long Tom sluices with their 'creative riffles' from the 1800s'. Yes, it was simple to rely on flatter, longer sluice boxes - but .......

It was quite intuitive for that time that 'slow and gentle' was the answer to that old, perplexing problem about the recovery of small Gold. Of course, that thinking persisted until the impracticality of slowly feeding low flow, low water energy was fully, completely and dramatically superseded by newer findings. Compared to earlier attempts to increase Gold retention, the Yukon testing of Lath 'n Moss by Poling and Hamilton produced substantially much higher returns. That new idea was "The New Standard" for a while - until about 2000 or so.

I, myself, was trained to think in that 'old timer's way' until Mike, a well known and highly experienced miner from right here on this forum, stopped in to visit me in Alaska for a week, way back in the mid 90s. His hard found and now shared concepts of increased water flow, moderately (some might even say small) sized catchments along with higher processing rates and recovery amounts were a bit hard for me to square up to all the 'old thinking from the Old Timers'. After all, I was fundamentally taught for years that "Low and Slow" was Absolute Fact for small Gold and, just like anything on the 'net just has to be true. We all know that, right?

So I listened carefully to "Mad Miner Mike", stood back and then started my own testing. Le Trap sluices were interesting but still used old thinking. Small expanded over thinner moss was better because the flow was more laminar. Then extruded black 'rubber' and craftily designed catchments came along to replace everything else in the box. The result was instantly seen and understood to be amazing. The Gold (weight and piece) recovered was drastically increased with much less (or no) classifying in smaller equipment. Medium and small, down to microscopic Gold size, recovery was drastically increased while any lost Gold in the tailings was, correspondingly, reduced. Smart, open minded small scale miners, today, are very enthusiastic about the results of this newer matrix for recovery. It's just much better and more reliable as ANY other general system used before.

Small scale miners are today's vanguard for efficiency in operation since narrow, smaller sluices with smaller pumps require high relative rates of hand fed (or dredged) material. The major truth here is that smaller, efficient, operations can be scaled up to commercial scale - whereas larger operations (using witchcraft and burlap) don't cut it when scaled down.

So, I do disagree with the old way of thinking that low water flow, flatter boxes, classifying to tight parameters while slowly coaxing small Gold from tailings because it just doesn't make any sense to me. The other inconsistency seems to be trying to, simultaneously, 're-invent the wheel'. Doubling or even tripling the volume of moderately sized bank run processed with a higher recovery just seems to be smarter than 'flat 'n slow'.

If a "Traditional Miner" chooses to slowly feed, low volume sluices on some test plant operation then it's simply that miner's choice or option. Trying to downplay or discount other current, highly productive techniques and products in favor of last century's techniques just won't convince those of us who really DO know better.

Of course - everyone will do what they think is right for what they "Just Know". Everyone thinks that "Their Situation" is just so absolutely unique that only They, working with Their unique situation, can come up with Their special answer.

I understand that type of approach, it's just that I simplistically choose to work with what is now working so well around the world. Sort of "If It Ain't Broke, Don't Fix It".

Good luck on mining your tailing piles - you certainly will come up with special and unique answers, no doubt.

Does anyone else have some thoughts on this small Gold size recovery? Inquiring minds want to know.

[Geowizard]

To avoid confusion;

The topic is "Counter Flow Sluice". This should not be confused with ALL other forms of sluices, old and new and the many semantics that have been the subject of debate over the past thirty years.

At the introduction, the concept of a multi-level sluice was brought forward. The Top level provides a high velocity stream where oversize is transported down and out of the sluice. The top level is punched plate. Punched plate provides a boundary between two velocities. High velocity on top and low velocity underneath. It also provides classification of sediments. In my case, the holes are 1/4 inch. Looking at the top of the sluice, the entire top level is 1/4 inch punched plate.

The sluice is set at almost 30 degree slope.

The obvious concern with an extremely high angle is the velocity of the water flow. This is where the "Counter Flow" comes into place. In order to slow the flow, a mechanism has to be in place to resist or impede the flow.

When GOLD goes from a high velocity stream to a slower stream, it tends to settle. Sediments having less "mass" remain in the stream and exit the sluice. With the appropriate mechanism in place, conditions can be made most favorable for small GOLD to remain in a sluice.

Expanded metal;

Expanded metal comes in two forms, flat expanded metal and raised expanded metal. Raised expanded metal has ridges that are slightly elevated and angled for use in walk ways in industrial areas. Typical application of raised expanded metal in a sluice box is to orient the raised edges down slope. Down slope orientation of the raised expanded metal provides an upward ramp with a sudden drop similar to a riffle! Thousands and thousands of riffles that catch GOLD.

In a "Counter Flow" application, the direction of the raised expanded metal is REVERSED!

That's right! Because the objective is to SLOW the flow, the reversed raised expanded metal creates thousands and thousands of miniature "dams". The dams also provide "pockets" for GOLD to settle!

From my research on the subject, this represents the FIRST published record of this method of COUNTER FLOW applied in a Sluice box used for concentration of placer GOLD.

The concept is important because it allows recovery of GOLD in a sluice that has an extremely high angle. The raised expanded metal is UNDER the punched plate! Top side of the punched plate is high velocity as is desired to push over-sized material out of the sluice box. Under the punched plate, the reverse raised expanded metal has the benefit of slowing the flow and providing thousands of pockets to catch GOLD.

I am demonstrating the Counter Flow Sluice in my mining operation this week at Ophir. It represents a "working model" that can form a basis for further experimentation with the Counter Flow concept.

Stick around and find out how well it works!

- Geowizard

[Joe S (AK)]

G-Wiz,

In your post (that portion which I specifically quoted so there would be no misunderstanding) YOU opened up the area of discussion by making some assumptions which were (in my personal assessment) ancient and no longer valid. That personal assessment was based upon substantial, verified information from the mining community over the last 8 to 10+ years. I quoted YOU in addressing what YOU wrote - and I certainly have an in-depth, valid, personal and professional insight into the subject matter I quoted. You seemed to be centering on old, old assumptions which may or more probably may not have been valid standards of thought long ago in the past. For example, referencing your startling, new idea of reverse standing expanded metal "riffles" – check out the design of Gold Hog highbankers. I know about them because I happen to own one. They have been using a large, single, across box “Reverse Ramp Riffle” for years, a lot of years. Large or small reverse riffles simply aren't a new concept. The concept of reversing the standing expanded metal in the lath field is generally not fully successful since the traveling water and slurry are usually swept or flushed away from the front of an obstruction (say a rock sitting in the stream) but are frequently dropped in the slower moving material in the 'back side shadow' of that same rock. That's the type of vortex protected area where the Gold drops much of the time.

Something I alluded to earlier - it's your claim, your choices, your gain if you are correct and your loss if you're wrong. If you choose to disregard the knowledge, experience or suggestions of others here then that's certainly your option. If you choose to disregard the accumulated years of experienced research, successful testing results and subsequent production of highly efficient equipment within the industry (that finds its way here) then it might get a bit exhausting for you in trying to re-develop all their findings. Trying to 'Cowboy' your way through a mountain of sluice designing, prototyping, testing, modifying and re-prototype testing along the trail of this project of yours could get mighty 'tiring'. But, then again, it's YOUR project - right?

One last thing, simply posting a pronouncement doesn't necessarily make it so in the calm, studied and experienced views of others here. There are many divergent, sometimes conflicting, thoughts on all facets within the mining industry and yours (or mine) aren’t always “The Right Ones”. If you want to share knowledge between equals here then that's fine, that's what we all should strive for and why we come here. That is the main strength of this forum. If you want to lecture like a college professor in the kitchen by redirecting thinking strictly to your “self proven” opinions then be prepared for the heat of that kitchen. Everyone here has experienced opinions and unlike you or I they are always well thought out and tested over time.

[Jim_Alaska]

Joe, I had thoughts along the same lines when I first read Chuck's post. I myself have used raised expanded metal that I reversed on many applications, both dredges as well as shoveling into various sluices.

I didn't reply with this information because Chuck was very exact in saying, "the FIRST published record of this method of COUNTER FLOW applied in a Sluice box." My using this stuff is far from "published", it was my own idea.

I still have one 2 1/2" dredge that I run the combination of reversed, raised expanded metal over backed Miner's Moss. There is diamond mesh screen over it all, so that all the oversize runs right out of the box, while allowing all the smaller stuff to make contact with and settle into the raised, expanded riffles. It works well for me.

Of course there are probably as many different combinations of recovery devices as there are miners. All my life I have seen miners always tinkering with their recovery units and sometimes even trying to re-invent the wheel, so-to-speak. We certainly have come a long way with recovery since whip-sawed wood sluice boxes and pole riffles. Hence the reason there is so much gold left in some tailing piles.

[chickenminer]

One of the MIRL reports had a paper by a graduate student named Godbey.
His paper was on fine gold recovery and had a section on reversed expanded and double reversed.
I remember some of his conclusions I had issues with but it was an interesting paper.
Seems like it was early '80's.
You might want to look it up Geo, if you haven't seen it.

[Geowizard]

The results are in;

I probably wasn't clear on this, but in the application I have, the sluice box is set at a 30 degree slope. The slope is determined by the angle needed to keep the top of the punch plate cleared off. The counter current is a form of braking action that SLOWS the flow under the punch plate. I appreciate all of the input provided.

I have ran the sluice and done a clean up. I can report that the design actually worked better than expected. The carpet loaded up nicely, sufficiently well to trap GOLD. The amount of water needed was about 400 Gallons per minute to keep the top deck clear. If a jam occurred, the water flow would cut a spillway and the brief, added velocity would quickly clear the jam. I cannot speak to the recovery because there is no way to know what went in versus what came out. The objective for me was to measure how well the counter action of the reverse raised expanded worked in the extreme elevation of 30 degrees.

There was NO blinding of the 1/4 inch (staggered holes) punch plate. Without protection, I expected the .125 aluminum punch plate to get bent up quickly, it actually was not bent up and remains in excellent condition.

- Geowizard