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dragline
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Fine Gold Sluice Design Help Needed ( 05:31:57 SunJan 8 2017 )

I am working on a fine gold sluice design that incorporates several novel features that, if proven successful, should hopefully provide efficient fine gold recovery, high productivity in terms of cubic yards per hour, and having a very small footprint.

I need your help determining the optimal slurry flow velocities for various operating parameters. For the purpose of these estimates you can assume that I will be employing expanded metal riffles (though I actually have something similar in mind).

I have noticed that expanded metal sluices designed for recovery of relatively coarse gold typically employ a fairly fast slurry flow velocity approaching 10 feet per second and in some cases even higher velocities when coarse gold predominates.

On the other hand, for beach mining applications where materials are highly classified (down to 1/16 inch in extreme cases) and when the riffle heights are very small (1/16 inch high riffles in the case of Clean Gold mats), optimal slurry velocities may be as slow as 2 to 5 feet per second.

Do any of you have references you can point me, or feedback from your experience, that I can use to correlate what might likely be the optimal slurry velocities when accounting for variables such as:

1. average gold mesh size (50% passes thru given mesh)
2. material classification screen or mesh size
3. riffle height
4. slurry density (percent solids)

Thanks in advance!

dragline
[2 edits; Last edit by dragline at 06:36:27 Sun Jan 8 2017]

  
dragline
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Re: Fine Gold Sluice Design Help Needed ( 19:28:19 SunJan 8 2017 )

Geowizard,

As always, I sincerely appreciate your response and insights into my design requirements.

I can tell you that I have been reading and posting here at Alaska Gold Forum since 2006, more than a decade, and I have not failed to read and digest every post pertaining to the technical parameters and requirements for the gravitational recovery of fine gold.

I apologize that my next statement, given in the form of a request, may not be completely accurate, but I would appreciate if you could please accept that I completely understand all of the technical requirements for the gravitation recovery of fine gold that you mention and that my purpose in posting my question regarding slurry flow velocities is highly targeted. Suffice it to say, and as hard as it may be to believe, several of the elements of my current sluice design efforts are completely novel and the only assistance I require at this time if information pertaining specifically to my question originally posted.

I am presently making an effort to finalize some of the key dimensional and power requirements I will need, as well as to acquire the raw materials and power equipment necessary to construct my very first prototype. In this regard I am attempting to establish dimensional and mechanical constraints so as to target specific ranges for the slurry flow velocity at a range of slurry solid percentages (densities).

The specific application for my prototype is for the efficient recovery of extremely fine gold such as we find here where I live on Oregon's Southern Coast. In many locations the presence of materials larger than coarse sand is nearly non-existent and so in some instances the classification of materials will be almost unnecessary, although my design incorporates certain features that have the ability to quickly and efficiently classify down to any punch plate mesh size desired, but for my testing purposes I will be evaluating 40% open area punch plates with 1/16", 1/8" and 1/4" diameter holes.

My current sluice development project utilizes riffles of my own design and manufacture, the 4-TPI extruded EPDM Sawtooth mat you probably recall from my previous postings here on this forum back in 2012. For more information about my 4-TPI Sawtooth EPDM extrusion see here:
http://bb.bbboy.net/alaskagoldforum-viewthread?forum=2&thread=1406

Anyways, thank you again and I look forward to any comments or suggestions you might have pertaining to gold mesh size, slurry flow velocity and/or slurry solids percentage.

dragline

  
dragline
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Re: Fine Gold Sluice Design Help Needed ( 04:19:16 MonJan 9 2017 )

Geowizard,

Yes, I appreciate your explanation and I apologize if my original question as first posted seemed ambiguous to you.

As previously stated, I am presently designing the overall mechanical and physical constraints that will allow some degree of variability among various control parameters for my prototypical sluice which I believe incorporates several somewhat novel design elements.

Presently there is only one sluice control variable for which I am seeking help, that of slurry velocity. Discussions of generalities or euphemisms pertaining to different mat or riffle types, gold purity or shape characteristics, or other sluice control variables are of little or no help to me at the present time. If you have actual experimental or production experience setting up and controlling sluice slurry flow velocity constraints than I am sure that you can appreciate the challenges I am up against.

If, on the other hand, you have no experience or appreciation for monitoring, measuring or controlling slurry flow velocity than I thank you for your interest in my project, but I do not believe there is a likelihood that any of the information or feedback you might provide will be of interest to me in regards to my current endeavor.

The specific types of conversations that I am seeking pertain to velocity in whatever metrics you care to reference, i.e. feet per second, meters per second, miles per hour, etc. Telling me that I must determine optimal velocities for my specific circumstances thru experimentation is also of no help to me because that is exactly what I am already doing. Please allow me to give you one example of a conversation (this one from my personal experience) that I am seeking and will appreciate.

Quote:

Back in the late 1970's I worked an entire summer with an 8 inch gold dredge on a claim I had on the Upper Middle Fork of the American River. The gold was coarse and the sluice I used incorporated 1 inch high Hungarian riffles on 4 inch centers. After some experimenting I determined the optimal degree of clearing for the riffles occurred with a slurry flow velocity of approximately 10 feet per second.


Of course my present efforts concern significantly finer mesh beach gold for which my recent experiments have indicated much slower optimal slurry velocities of about 4 or 5 feet per second. However, I recognize that there may be many other placer miners out there that have undertaken efforts to monitor, quantify and control slurry velocity and I would be very interested in hearing what anyone might have to say in these regards.

Thanks again for your understanding.

dragline



[1 edits; Last edit by dragline at 06:09:13 Mon Jan 9 2017]

  
peluk
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Re: Fine Gold Sluice Design Help Needed ( 01:11:02 TueJan 10 2017 )

"The operation recovered about 50% of the gold." It seems that a mining operation could do well to sell tailings as not just road bedding or pad material but as gold bearing ore. Tailings are being gone through for profit now.Why not set valuable tailings aside where they are accessable to a trucking firm for sale to whomever is interested. These Nome roads are built on some very good material for example.

The often heard response to losses is that we can do better just running more material faster,recovering more gold and absorbing some losses.No sense arguing the point but hey,some people would be able to deal with that material elsewhere I'd bet.
In Nome there are definitely such worthwhile tailings available.Even set up as a tourist operation,this material should not be wasted as fill.

  
dragline
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Re: Fine Gold Sluice Design Help Needed ( 02:20:33 TueJan 10 2017 )

Geowizard,

The example of a type of conversation that I gave was just that, an example of a conversation I would be happy to entertain. Your saying it was irrelevant may be true, but it is only irrelevant from your perspective, not mine. The reason I would gladly entertain conversations such as I gave in that example is because in that example there was included a statement related to slurry velocity, i.e. 10 feet per second.

I posted an inquiry here on this forum regarding my solicitation for help with my sluice design pertaining to slurry velocity and that is exactly the topic of conversation I was hoping to engage the community of miners here. I was hoping you may have had experience or an appreciation for slurry velocity. Perhaps you do, or perhaps you do not, but should you not understand this concept I will bet you that there are members of the forum here that do understand what velocity is and how measuring and controlling slurry velocity may relate to optimal sluice performance.

My use of the word "novel" relates to a somewhat technical use of the word in the legal terminology pertaining to patents. Because I make the claim that certain elements of my design are "novel" it means that i am keeping these design elements close to my vest and that I am not wanting to entertain discussions pertaining to these design elements.

Please accept that I am not seeking your assistance, or the assistance of anyone else here, in maters pertaining to the novel design elements of my current project. I merely wanted to engage the community here in generalized, experiential, theory or academic discussions pertaining to slurry velocity and various sluice components, control variables and methods that may be directly related. I also have no interest in discussing my Sawtooth mat, any other mats, riffle designs or anything else in this specific thread.

If I am in any way out of bounds here in wanting to engage this narrow focus of conversation, or if it is inappropriate for me to want avoid the discussion of details pertaining to the novel design elements of my sluice project, please accept my apologies. Perhaps Alaska Gold forum is the wrong forum for me to entertain such targeted and narrow technical discussions pertaining to sluice engineering.

I probably should have been more clear right from the beginning about my desire to keep a narrow focus of conversation pertaining to slurry velocity and if that is not a topic of conversation you are able or willing to engage narrowly please accept my apologies for not letting you know sooner.

Perhaps there is someone else here on the forum that is willing to offer me their feedback regarding slurry velocity?

Take care,

dragline

  
chickenminer
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Re: Fine Gold Sluice Design Help Needed ( 02:54:12 TueJan 10 2017 )

Dragline...
Since you are designing a "new" system I would suggest digesting the available fine gold studies like Clarkson, Poling/Hamilton and Mitchell/Evans/Styles.

Then a bunch of trial and error testing with your new system.

Good luck



---
Dick Hammond - Chicken, Alaska
Chicken / Stonehouse Creek Mining
Chickenminer.com
 
 
peluk
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Re: Fine Gold Sluice Design Help Needed ( 03:01:50 TueJan 10 2017 )

Dragline,you could take some typical material and run it through a slower but very accurate clean up system to determine how much gold you could expect from a known quantity. Then,with a tub at the end of your sluice set into a containment pond or pool,you could experiment with various flow rates.See what you recover and see what you lose. Do it again and again until you have results you can live with.

Feed rate should probably approximate what dredgers have come to accept. I believe that is a 20/80 material to water ratio.That should/will prevent choking or overfeed.
Find out where the gold collects and if it migrates over time as it looks for an ideal spot in your bedding. When you get to the point that it starts to spill out of the box,shut down and clean up.
If it is beach material you are running,with little silt,you should be able to visually determine where the gold is collecting.

  
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Re: Fine Gold Sluice Design Help Needed ( 04:15:21 TueJan 10 2017 )

Dragline,

I admit that I am a bit biased, but also know that this forum is the best place to get technical assistance. Although the replies so far have not been exactly what you need, I don't believe there is a better place to get what you need.

No other forum that I am aware of has the resident expertise in the form of people doing large scale, complex mining as we have here.

The forum has been a bit slow lately in participation, but I would encourage you to not give up. People don't visit the forum so much when posts slow down and there isn't much to read or respond to.

Hopefully someone with the knowledge you need will see your post and respond.



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JOE_S_INDY
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Re: Fine Gold Sluice Design Help Needed ( 09:19:35 TueJan 10 2017 )

Dragline,

Doc at Gold Hog explained a technique that might have relevance here.

He suggested setting a box up so that TOO much water velocity goes through it while maintaining a set GPH. Blast out all the material, Gold and all. Then, incrementally, begin to flatten the pitch (drop) of the box. At some drop rate or angle only the very densest materials will start to accumulate in your catchments. Go a little further in stages until just a little of the lighter black sands begin to be caught. One more flattening and the Gold and only some small amount of black sand will be kept behind in the catchments - while everything else is released back into the wild off the back end of the box.

Once the "sweet Spot" is found then it can be recreated on every setup.

After all, we're looking to retain Gold here and not so much the lighter materials.

Joe






---
Wiser Mining Through Endless Personal Mistakes
 
 
dragline
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Re: Fine Gold Sluice Design Help Needed ( 07:02:49 WedJan 11 2017 )

chickenminer,

Of course. I have read these studies and I found the Poling/Hamilton from the Univ of British Columbia work and accompanying DVD very helpful an most informative regarding the detailed records and experimentation that included data gathering for sluice slurry velocity. I only wish that the DVD were available on YouTube but I haven't seen it there. Perhaps I'll dig thru my DVD collection and post that to YouTube on of these days.

In the regard of the available academic studies pertaining to sluice technologies I believe I am comfortable with my current studies in that I am confident that my academic studies are sufficient to get me thru my current project. My specific need and request for comment or feedback at this time specifically relates to slurry velocity and how various features of sluices may influence the requirement for establishing the optimal slurry velocity for those configurations.

From my research and experience sluice slurry velocities tend to range from as slow as 3 to as fast as 15 feet per second. Perhaps there are occasionally instances where optimal sluice slurry velocities fall outside this range but I am curious as to whether members of the forum might have information or experience in measuring an optimizing slurry velocity for their specific fine gold recovery requirements.

Thank you for your input.

dragline

  
dragline
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Re: Fine Gold Sluice Design Help Needed ( 07:29:19 WedJan 11 2017 )

peluk,

Yes, I do understand and I do occasionally engage in the principles and practices of ore materials testing and I hope you can accept that I am not lacking in knowledge or experience pertaining to the operation and optimizing of various sluice types for specific ores.

While I sincerely appreciate your feedback and help I had really hoped to avoid my having to recount or explain all of the various types of sluices I have built, operated and tested in conjunction with my placer mining activities over the last 40 years.

In regards to your reference to the 20/80 material to water ratio, I would beg to differ with this estimate. The studies that I am familiar with that have employed very strict controls and analytical methods have determined that there is no practical upper limit to the slurry solids percentage. For many practical reasons most mining operations and sluices are not configured or set up to work with a high solids percentage slurry but some studies have show extremely fine gold recovery efficiency actually increases as the slurry solids ratio increases up to in one study I read, 70% solids percentage.

My understanding regarding why very fine gold recovery efficiency increases with the solids ratio has to do with the fact that a more dense slurry will absorb and dissipate slurry turbulence energy in the form of heat due to markedly increased collisions. Even though small particles of gold will fall much more slowly thru a dense slurry the decrease in turbulence allows an increased likelihood of capture and sequestration at riffle eddies and without as much tendency for random turbulence to dislodge sequestered fine gold and return it to the slurry.

Anyways, as always, I appreciate your feedback and wish you all the best with your mining efforts there in Nome this coming year.

dragline

  
dragline
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Re: Fine Gold Sluice Design Help Needed ( 07:36:24 WedJan 11 2017 )

Jim_Alaska,

Thank you for your kind words of encouragement. Just so you know, I have been thinking about my claims of novel design elements pertaining to my current project and have determined that I will be able to remove all of these supposedly novel elements and post my public domain designs here soon, hopefully sometime next week should my schedule permit.

Thanks again,

dragline

  
dragline
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Re: Fine Gold Sluice Design Help Needed ( 07:53:55 WedJan 11 2017 )

Joe S Indy,

Yes, thank you for your feedback. I must apologize that my current designs are not conducive to such conventional fine tuning techniques as you mention from Doc over at Gold Hog.

If my designs go according to plan I should be able to blast ether water or very dense slurry across the sluice riffles at velocities too high and/or too slow for efficient fine gold recovery. Of course somewhere in between these slurry velocity extremes there should be a sweet spot where optimal recover will occur for my specific placer ores. I believe that I am capable of arriving at that optimal velocity thru experimental and analytical methods.

I ask that you be patient with me a few more days so I can go back to the drawing board (computers these days) and rework my layouts so as to remove any and all of my supposedly novel design elements.

Once I am able to do that, hopefully sometime next week should my schedule permit, I will post layouts here that will hopefully make clear why my current focus on slurry velocity is so very important to my current designs and why most conventional sluice configurations and operational methods are not entirely pertinent.

Thanks again,

dragline


  
dragline
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Re: Fine Gold Sluice Design Help Needed ( 08:24:57 WedJan 11 2017 )

geowizard,

Regarding my claims of novel design elements and my public disclosure of those designs, my plan is to build and test a prototype and should those efforts prove successful I will then file a US Provisional Patent Application. After I do that I will publicly disclose the details of my novel design elements here on this forum.

In regards to the fine gold of Nome's beaches, Peluk is definitely a master at fine beach gold recovery and cleanup. There is no doubt about that. For the last decade I have eagerly read Peluk's every comment here on this forum.

The fine gold on Oregon's Southern coastal beaches is similar in this regard although there may be beaches here with even finer gold than is typical on Nome's beaches. Either way, very fine beach gold presents unique problems that demand unique solutions, but with those solutions come tremendous opportunities.

With your wash plant, you calculated that your flow rate (slurry velocity) is 2.2 feet per second. This seems extremely slow from my experience. One simple way for you to verify your calculations would be to place a floating object (I use a cork) at the top of the sluice and then use a stopwatch to time the transit down the sluice.

Given your stated wash plant setup a cork would take almost 5.5 seconds to transit the 12 feet from the top to the bottom of your sluice. This must be the slowest slurry velocity I've yet encountered, which I would think would be extremely efficient at capturing extremely fine gold given everything functioning properly and without excessive blond sand buildup in the riffles.

I never would have thought a sluice could be designed to operate efficiently at such a slow slurry velocity. That is awesome! When my slurry velocity runs that slowly there is very little clearing and terrible efficiency. Perhaps I can figure out how you did that.

I sincerely appreciate your feedback.

Thanks,

dragline
[1 edits; Last edit by dragline at 08:30:13 Wed Jan 11 2017]

  
dragline
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Re: Fine Gold Sluice Design Help Needed ( 16:04:03 WedJan 11 2017 )

Geowizard,

Your comment:

Quote:

Everybody's sluice box is subjected to the same laws of physics.


True. The universe contains only one set of physical laws that apply universally. However, some sluices exhibit increased or decreased efficiency at fine gold recovery depending upon how those physical laws are applied.

For me to say that the universe of possibilities regarding the application of physical laws and fine gold sluices are in keeping with the way my thinking or experience dictates then my thinking would be both arrogant and narrow minded.

In keeping with and furtherance of your just mentioned example, it should be understood that fine gold sluices fall into the category of gravitational gold recovery technologies. Other technologies exist but our current focus relies mostly upon little g, not so much big G (the universal gravitational constant).

Since you were kind enough to offer me a thought experiment, please allow me to return the favor:
Imagine you had your same 12 foot wash plant sluice setup such that the slope was up hill 9.46 degrees, not down. Can you imagine any set of circumstances in which our universal physical laws might favor this up hill setup such that it was more efficient at fine gold recovery than your down hill sluice?

If a sluice setup with an up hill slope of 9.46 degrees was capable of maintaining uniform slurry depth and velocity across the entire 12 foot sluice length then I maintain that fine gold recovery efficiency might actually be increased relative to the same exact sluice flowing down hill at 9.46 degrees.

Of course anyone familiar with setting up sluices might be tempted to say that an up hill sloping sluice would be impractical and would not work for a variety of reasons. But for the purpose of this thought experiment I beg your indulgence and feedback for a moment.

dragline

  
dragline
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Re: Fine Gold Sluice Design Help Needed ( 16:29:41 WedJan 11 2017 )

Geowizard,

One comment I forgot to mention regards your calculations for slurry velocity based upon your sluice slope angle and g = 32 feet per second per second.

So as to better communicate my comment I'll present you with another thought experiment for you in the form of a question:
Imagine all other factors pertaining to your current wash plant setup are identical, i.e. your hopper, grizzly, feed box and tails discharge remained unchanged. The only thing you change is your sluice slope angle to 0 degrees, i.e. level. Based upon your previously employed calculation methods and algorithm, what slurry velocity would you calculate flowing out the end of your sluice to tails?

Thanks,

dragline
[1 edits; Last edit by dragline at 16:33:27 Wed Jan 11 2017]

  
dragline
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Re: Fine Gold Sluice Design Help Needed ( 17:24:37 WedJan 11 2017 )

Geowizard,

Regarding my question pertaining to your calculated slurry velocity at zero degree drop you responded...

"Output = Input"

Does your response answer my question? I do not believe that it does.

I asked you to use your algorithm and calculate slurry velocity with a sluice slope of zero degrees.

When I attempted to use your algorithm I calculated a slurry velocity of zero feet per second. This result seems absurd to me.

I suspect that your algorithm may be inaccurate because it fails to factor in your "Output = Input" consideration, i.e. the slurry velocity thru the sluice will be more than the your algorithm dictates because of the slurry velocity and momentum entering the sluice head is a major consideration.

Therefore, I suspect that your actual wash plant slurry velocity will be somewhat greater than your algorithm calculated 5.26 feet per second which in my opinion makes the case for measuring slurry velocity experimentally.

Thank you,

dragline
[5 edits; Last edit by dragline at 17:49:38 Wed Jan 11 2017]

  
LipCa
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Re: Fine Gold Sluice Design Help Needed ( 17:37:12 WedJan 11 2017 )

I'm no expert with sluice box calculations so I'll just throw this out......

I have always thought that the water always flowed pretty much flowed horizontal in my box, not vertical... little did I know:smile:
I know that it tries to flow vertical but is stopped by the box and continues to "slide" down the box in more of a horizontal motion than a vertical motion?
It flows in an ever changing velocity throughout the depth of the water. Faster on top and slowest on bottom.

At some point, when material is introduced into the box, you want the fine gold AND all sizes of gold to settle to the bottom of the box!
Where this happens in the box depends on:

The type, size and feed rate of the material.
The amount of water induced and how it is induced.
The slope and configuration of the box.
The bedding in the box.
(can't think of any more?)
They all are variable

In my experience, experimentation is the only solution!!


"In my case, the common off-the-shelf raised expanded with astro-turf recovers ALL of the gold. :confused:

I have a helper that continually monitors the output of the sluice - in real time. A pan is placed at the output of the sluice. The contents are carefully panned and the amount of gold is noted. No gold is leaving the sluice. As I mentioned, the gold is recovered in the first four feet of the sluice box. About a gram of gold is recovered in the second four feet of carpet. That represents less than 3 percent of the total recovery. About 3 percent of that 3 percent is found in the third - four foot section of carpet.

Geowizard, is your box only 4 feet long?


  
LipCa
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Re: Fine Gold Sluice Design Help Needed ( 01:56:46 ThuJan 12 2017 )

ok, got it....

  
dragline
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Re: Fine Gold Sluice Design Help Needed ( 14:39:03 ThuJan 12 2017 )

Geowizard,

I apologize that I don't understand your "PUBLIC DISCLOSURE" post just now. Please help me understand the point you are making here in regards to a novel idea reducing footprint by eliminating a conveyor. Is this a project you are working on? Please tell us more.

Thanks.

dragline



[1 edits; Last edit by dragline at 14:39:27 Thu Jan 12 2017]

  
dragline
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Re: Fine Gold Sluice Design Help Needed ( 22:31:24 ThuJan 12 2017 )

Geowizard,

That sounds awesome! If you can post any information here about your Maxi-Banker I'd like to see what you have going there. I always appreciate anyone's efforts to help people earn a living, and should hard times hit the American people again as happened back in the 1930's, mining may save many families.

I do have a high-banker version of the sluice project I'm working on but that's probably a ways down the road. The problem I have is that grizzly/hopper footprints tend to be huge and reducing those to fit over my sluice won't be easy. So for my current design I won't be attempting anything beyond the basic proof of concept for the 150 to 200 gpm suitcase sluice.

When it comes to slurry velocity, the one thing that I believe that everyone here can agree on is that faster slurry velocities increase production volume, are capable of clearing larger gravel and rocks, but fine gold recovery efficiency may suffer. If one is only dealing with coarse gold, i.e. 20 mesh or larger, the velocity can be quite high without concern.

But for very fine gold where a significant percentage is smaller than 100 mesh, such as we have her on Southern Oregon beaches, slurry velocity must be very slow in comparison. And, a slow slurry velocity will require a great deal more classification so as to eliminate 1/8" or larger materials.

I was just hoping to get some feedback here from miners that have undertaken the effort to measure slurry velocity for a given gold mesh size but perhaps I'll just have to make my best guess about what velocities might be optimal for various gold mesh sizes.

I've gotta travel out of State for a few days so I may not be responding in a timely manner. But if anyone has any guesses as to what slurry velocities I should target for specific gold mesh size ranges please post your comments here.

dragline

  
dragline
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Re: Fine Gold Sluice Design Help Needed ( 04:10:08 FriJan 13 2017 )

Geowizard,

Wow! Thank you for your search references. I read every one. Your Maxi-Banker was huge! Two 3 ft x 16 ft sluices and a 6x6 ft screen. That setup would sure process a lot of dirt! Can you tell me what your final screen mesh size was? How did you capture and retain nuggets that were oversized relative to your screen?

Can you tell me about your pump capacity in gallons per minute and whether you could throttle up or down the flow rate to find some optimal flow?

My current efforts are considerably scaled down from your Maxi-Banker. I'm starting with one 7 HP 208cc gasoline trash pump capable of 300 gallons per minute (realistically capable of about 160 gpm under moderate load and less than 15 feet of head).

Right now I'm targeting a very slow range of slurry velocities of 2.5 to 5 feet per second with my initial prototype but I would also hopefully be able to push solids to 50% or more if I can get the hydraulic dredge ratio under control. Beach sand can exhibit a very strange phenomena when liquefaction turns supposedly solid land into a soupy slurry with a little water and agitation.

dragline

  
peluk
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Re: Fine Gold Sluice Design Help Needed ( 05:40:37 FriJan 13 2017 )

This excerpt is from extensive notes from here and there regarding earlier efforts to work with Peluk Creek gold.
This is from "Mining and Scientific Press" 3/1911 edition.

This commentary describes the gold which has not washed out of the tundra.When it is on the actual "present day beach" which joins the water,it has similar qualities.

"Described as flakey,mostly fine and it carries through the sluice in suspension". A later miner seeing the nature of the gold thought it best to "use of drops and undercurrents". In working with this beach gold I have used various methods as have others out there.The riffles have been abandoned and a smooth flow seems best for our beach gold so it can settle into the bedding or get pulled out of the flow and held by ribbed rubber design.

Here's the odd part. Only last year it occurred to me that my most productive beach box has a hopper set at somewhere around 45degrees. I have galvanized window screen of probably 17-19 mesh as my screening surface.The lower part is at 7-9+ degree range. The screened hopper with moss over ribbed carpet is by far the most productive recovery medium.What gets past there will get caught in the lower flared bed with its recovery schedule and I am satisfied with my accuracy.It's odd that with all the thought that goes into the grade on the lower end,the 45 degree grade of the top hopper is extremely efficient. I also think the flared design of the bottom compliments the flow rate of the hopper.

These are just observations that may indicate there is more than one way to grab gold out of the flow.

  
LipCa
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Re: Fine Gold Sluice Design Help Needed ( 17:54:17 FriJan 13 2017 )

I remember someone testing astro turf carpet(maybe it was you Peluk?) and I though they found that it filled up and gold washed over the top.
Yet, Geowizard uses astro turf that catches ALL the gold:smile:
Maybe it is the type of astro turf used?

  
peluk
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Re: Fine Gold Sluice Design Help Needed ( 07:42:23 SunJan 15 2017 )

LipCa,you are correct. At production speed that matches the feed rate of a normal beachbox including the "Nome Beachbox" by Keene with their rippled mat,"Astroturf" packs up. It is meant for slow feed,well watered and it does no good if choked in sand.So,I can only use it for cleanup work at this point.The Astroturf I'm speaking of is the "daisymat" doormat material.it looks like grass.

Some miners would look at the feed speed in a beachbox and they would want no part of it after feeding a hopper with a loader or excavator. The difference is that good beach material has an extremely high content of gold per measure of host material assuming it has been tested and not fed randomly from anyplace.Patience pays dividends with little expenditure.

  
LipCa
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Re: Fine Gold Sluice Design Help Needed ( 17:17:06 SunJan 15 2017 )

Geowizard,

Out of curiosity, I know where you come up with two five gallon buckets of concentrates from your operation. But, where do you arrive at one third to one half bucket of concentrates from a beach box?
"One cubic yard of sand should produce less than one quarts (1/50 x 10 gallons) of concentrate".
So, 2 cubic yards produces 2 quarts? etc.. After you run 6-10 cubic yards, you have produced 6 to 10 quarts of concentrates( one third to one half bucket ),
Second question, Is that the max you can run through a beach box that size as it will only hold so much concentrates?


  
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Re: Fine Gold Sluice Design Help Needed ( 19:33:25 SunJan 15 2017 )

Of course "The operations are entirely different in scale" :smile:

I guessed that you were maybe using simple proportions...

I would have thought that the dynamics acting on the concentrates would be extremely different between your operation using riffles and carpet and a beach box using only carpet.
So, maybe a simple proportion wouldn't apply?

Maybe a cubic yard of sand might only produce a tablespoon of concentrates?


  
LipCa
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Re: Fine Gold Sluice Design Help Needed ( 01:32:02 MonJan 16 2017 )

And one cubic yard of sand run through a beach box with 22 gallons per minute and "15 percent solids slurry" could leave no concentrates if there are none in the sand.
I was simply trying to figure out how you arrived at "1/3 to 1/2 of a bucket" of concentrates from a beach box?

  
LipCa
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Re: Fine Gold Sluice Design Help Needed ( 04:59:23 MonJan 16 2017 )

Thank you:smile:

  
LipCa
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Re: Fine Gold Sluice Design Help Needed ( 17:20:34 MonJan 16 2017 )

Geowizard,

You keep doing this to my brain :smile:

Your previous post put the amount of concentrates from that size beach box at 1.65 to 2.5 cubic gallons. (A Nome Beach box one feet wide x 4 feet long would have about 1/3 to 1/2 of a bucket)
According to your latest post, a "loaded" carpet contains 0.625 cubic gallons?

I must assume that you were "observing" a different size box?

  

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