RotGrub

Recirculating Highbanker W/ Vortex Sand Separator

45 posts in this topic

Simple is subjective. We mine in an area with good gold but no water. Working through the recirculating issues is our advantage. It takes a bit of planning and work but every year our recovery has improved due to the improvements in our equipment. I see it as opportunity and enjoy the challenge :)

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  This could become an interesting thread over time.  There are a lot of locations that are too wet for a dry washer, and too dry for a wet washer, and where a "practical scale" recirculation system would be ideal...   ("practical scale" meaning 1+ tons of material per day, or, per water-haul)
 

 This is not a small challenge..  in round numbers for easy math ,   let’s say a 10 or 12 inch high-banker could use 50 gal per min, that is 350 lbs. of water every 60 seconds.  And in those 60 seconds, you might be able to get 50 lbs. of material (most of a 5 gal bucket) through the sluice, so that is a 7 to 1 water to material use ratio.  At this rate, to process 1 ton of material (40, 5 gal buckets), would require 14,000 lbs. (2,000 gallons) of water...    "Practice" would mean getting this done with a few hundred gallons of water (not a few thousand).

 

  ROTGRUB has been nice enought to shair his results on YouTube, and I have picked up some good point from his efforts to improve the practicality of a recovery system that uses "portable" water recirculation (buckets or barrels) rather than settling ponds.  A lot of ROT's work has been around recovering the used water from the slurry discharge (the screen in the video), and then filtering the recycled water (which is used over and over again) to reduce the particulate build-up.   ROT's "Material run vs Water used" ratio is really pretty high.

 

  The approach that I have been working on, is to devise a "separation system" that uses the absolute minimum amount of water, which would be just enough water to make the "slurry" (pre-sized to 1/8") become the consistency of oatmeal or soupy concrete.  This thick gluppy slurry is then "run over" a vibrating "sluice /tray" which is lined with GoldHog matting (put in backwards) to create the retention riffles.  The vibrating sluice pan is run at a slight angle, (~1/2 inch per foot) just enough to keep the material moving down slope…
 

  The vibration speed and the clay component in the slurry are the difficult variables I am working on now... I started out using a Vibco 12-volt vibrator on a speed control...  but in some cases this caused the slurry to get compacted...  I think a directional shaking action will be better for keeping the slurry in a semi-liquefied state, so I am working on a cam shaker set up …

 

 

All good fun...

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Here are my thoughts:

Interesting idea, but it wont work. In order to run a longer term recirculating sluice in dry area, removing sand wont cut it.The problem is almost never the sand, but the clay. If you don't remove the clay and silt, in a short time your water will be thick as molasses. Thick, viscous water does not allow gold to settle, and if the gold wont settle in your sluice, it wont be recovered, and if you are not recovering your gold, whats the point? You don't want to run a thick slurry over any kind of sluice or matting as you are not letting the gold settle properly and you will get a terrible recovery percentage. You may even find clay clogging up your riffle areas and preventing gold from being caught.

 

The enviro-nuts object to the fact that you darken the water - AKA an increase in turbidity - and no centrifuge, no matter what your design will take out the clay because clay particles are so very tiny in size. Centrifuges just don't handle those really tiny particles. Removing clay and other real fine particles requires a lot more than just a centrifugal sand separator - usually flocculation, settling systems and other such equipment, way too much to try to make portable for an individual prospector.

 

I'd look for some way to just bring more water with you. If you are staying for a few days and really want to reclaim, maybe bring some 20 gallon drums of water, then an empty 50 gallon drum. put your used water in the 50 gallon drum, add flocculant, and let sit and settle overnight. The next morning, you should be able to reclaim for reuse about 1/2 to 2/3rds of the muddy water for reuse. You will lose a fair amount of water with just the drag out of the wet sand and gravel, but with a flocculant, you can at least re-use some of it.

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OK now we're getting somewhere... A bit more info.

 

We began this recirculating quest around 2010. There is a dry creek that has gold but was avoided for the most part due to the lack of water. I poked around the area and found enough gold to rethink my options. Our first system was just a 70gal feed tub with a 5gal bucket placed in the supply tub to catch the tailings. We transported water in a plastic 55gal barrel and gravity fed the supply tub with 200' of water hose. When the tailing bucket filled, I just dumped and replaced. This simple system dramatically increased our production and recovery. The highbanker was modified by closing up the grizzly bar opening and all other holes and we classify to -1/2" before running the material. In time I reconized the shortcomings of this system: water loss and only 20 or so buckets of material before the water was usless. See it here: The intro might be a bit much for some of you... just jump to 4:30 on the video.

 

The 2nd gen system needed to reduce the water loss and increase the water life. I modified the HB by sealing all leaks and created the first tailing screen with SS 60 mesh which was placed over the supply tub and inline with the sluice box. I also installed a bulkhead into the supply tub to clean up the hose management and installed a 60SF pool filter for filtration. This was the first Ecobanker and you can see it here:

 

After testing the 2nd gen system in the field we found that the pool filter was not a good choice as it plugged up after 1 bucket... The tailing screen however worked great in separating the +60 material from the supply tub. We then came up with another idea to manage the fines which smoked my pump seal and set me back $80... I drilled three 2 1/4" holes into the upper third of a 15gal plastic tub and another for the suction hose on the opposite side. This tub was placed into the 70gal supply tub and covered with a plastic lid. I then added a slurry tray under the tailing screen to direct the slurry into another rectangular mop bucked placed into the 70gal tub. My thinking was to first protect my pump and to better manage the -60 slurry by directing the majority into the mop bucket which could be quickly dumped. The 15gal tub allowed much of the slurry to settle onto the bottom of the 70gal supply tub while the three 2 1/4" inlet holes reduced the fines from entering my pump. This system worker all last summer without further damage to my pump and increased our water life to 30-34 buckets. You can see the 2nd gen system here:

 

3rd gen system: I need to find out how much slurry the vortex will trap. I realize that it will not trap everything but what percentage will it trap and will it be enough to incorporate a 100-200 micron filtrating tank after the vortex. The first plastic barrel collapsed under the negative pressure. I found another tank made from structural foam which is very strong. In my first test, the vortex spun down material as hoped, but there are still a few issues that need correction. I should have a video up in a few days to show my progress.

 

My goals: To create a system that will recycle approximately 75-100 gallons of water suitable for running the highbanker. We're not talking about clear water, just maintain an acceptable level of filtration to highbank.

 

Thanks, I've received some of the best comments and information from the members of ICMJ. This can be done if we work together.

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  This could become an interesting thread over time.  There are a lot of locations that are too wet for a dry washer, and too dry for a wet washer, and where a "practical scale" recirculation system would be ideal...   ("practical scale" meaning 1+ tons of material per day, or, per water-haul)

 

 This is not a small challenge..  in round numbers for easy math ,   let’s say a 10 or 12 inch high-banker could use 50 gal per min, that is 350 lbs. of water every 60 seconds.  And in those 60 seconds, you might be able to get 50 lbs. of material (most of a 5 gal bucket) through the sluice, so that is a 7 to 1 water to material use ratio.  At this rate, to process 1 ton of material (40, 5 gal buckets), would require 14,000 lbs. (2,000 gallons) of water...    "Practice" would mean getting this done with a few hundred gallons of water (not a few thousand).

 

  ROTGRUB has been nice enought to shair his results on YouTube, and I have picked up some good point from his efforts to improve the practicality of a recovery system that uses "portable" water recirculation (buckets or barrels) rather than settling ponds.  A lot of ROT's work has been around recovering the used water from the slurry discharge (the screen in the video), and then filtering the recycled water (which is used over and over again) to reduce the particulate build-up.   ROT's "Material run vs Water used" ratio is really pretty high.

 

  The approach that I have been working on, is to devise a "separation system" that uses the absolute minimum amount of water, which would be just enough water to make the "slurry" (pre-sized to 1/8") become the consistency of oatmeal or soupy concrete.  This thick gluppy slurry is then "run over" a vibrating "sluice /tray" which is lined with GoldHog matting (put in backwards) to create the retention riffles.  The vibrating sluice pan is run at a slight angle, (~1/2 inch per foot) just enough to keep the material moving down slope…

 

  The vibration speed and the clay component in the slurry are the difficult variables I am working on now... I started out using a Vibco 12-volt vibrator on a speed control...  but in some cases this caused the slurry to get compacted...  I think a directional shaking action will be better for keeping the slurry in a semi-liquefied state, so I am working on a cam shaker set up …

 

 

All good fun...

Great concept. If I understand you correctly; would a small profile drop riffle say 1/4" attached to the vibrator without mat help move the material but allow gold to settle into the drop? Got any pictures???

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Sorry I don't have any pix with me, and I am out of the country right now... But I'll take some when I get back...

The "drop riffle" idea is interesting .. the Gold Hog "Scrubber" mat has some drop riffle chariteristics, and it requires a continuous drip of water into upper "flights" of the mat to help keep the slurry liquified. The vibration tends to seperate some water from the slurry, and the free-water travels down slope faster than the higher solids content slurry. This helps the bottom flights to stay wet, but the upper flights will not "migrate" without the extra water...

You have also give me the idea of just vibrating the "riffles" and leave the sluice-tray stationary and almost flat, which could open up a whole new set of possibilities ... (the riffles would not be conventional sluice riffles, but more like a "live-floor" in the bottom of the sluice-tray that would "walk" the slurry down the sluice-tray while separating and holding the heavies in retention at the bottom of the tray..

This idea would be something like a "low viscosity jig", with the retention area having to be cleaned frequently ... But humm... A interesting idea...

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Rotgrub..

  I tend to agree with Chris. In trying to meet water quality standards the settable solids issue was never a big concern. With just a basic

settling pond we can meet those standards. The real kicker is the turbidity limits. Those nasty suspended solids that take forever to settle.

 

 If it were me I think I would spend my time developing a series of "ponds", rather than trying to scalp the sand off.  Which as Chris says,

isn't the problem in suspended solids. Then again, you may hit on a combination of the two as the most feasible solution to your issue.

 

You may need more water to begin, but in the end you will be ahead. Or so it seems to me.

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We run a recirk down here in the desserts of south Arizona using a 75 gallon horse trough just catching our tailings in a 5 gallon bucket. One goes in one comes out I run 50 buckets per day on 120 gallons of water using a 5hp trash pump. Gotta shovel out silt at lunch time and refill, dont notice too much sand in there though. Doing the recirk thing is a real pain in the butt except we average 1/3 oz a day or sometimes more  :ph34r:  :ph34r:  

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recirc.jpg

 

As basic as it gets:

 

Relatively poor material over bedrock was shoveled aside. Last few inches on bedrock removed plus bedrock thoroughly split and creviced. Material then pre-sceened/washed into water filled tub through a classifier to roughly 1/2" minus.

 

Honda WX10 pump draws water from tub to run sluice off 1.5" suction dredge, sluice hand fed pre-screened material. Tailings into a tub which overflows into the WX10 water pickup tub. Tailings dumped back into excavated bedrock area as operation proceeds. Maybe 25 gallons being used total, loss made up from gully several hundred feet away. Roughly 1/4 oz per day production.

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Ok, let’s try it another way.
 

How much or what percentage of solids in the water supply would be acceptable to process the material? From my experience I can run about 30 buckets of -1/2” material into 55 gallons of supply water before it gets a little thick. For arguments sake, I could probably run more but at that point I’m more concerned with damaging my pump so let’s say 25 buckets worth of suspended clay is our target.
 

Now, for every 5gal bucket of -1/2” material the tailing screen eliminates approximately 90% of the volume from entering the supply tub. The remaining 10% passes through the 60 mesh and enters the water supply. (I understand that this ratio will change depending on the material properties) So for every 10 buckets of material run through the system 5 gallons of slurry enters the supply water. So for a 25 bucket run 12.5 gallons of slurry is in the water supply; or 23% as I see it. Maintaining this ratio or less is my goal.

 

What I’m after is reducing the percentage of solids from circulating in the water supply which should extend the water life. I realize that a filtration system designed to remove all solids on the fly would be very expensive due to the high pressure and related equipment necessary to trap all solids on the fly.

 

So if I could trap something like 50% of the suspended solids from reentering the supply water it should extend the water life by an additional 50% or 43 buckets with a 55gal water supply. Now, in order to trap 50% of the 25% of slurry that entered the system, I will need to add another tank to house the vortex which increases the initial water supply by some factor. That factor is a bit harder to identify due to the nature of the vortex tank and how much water will actually circulate into the system due to the negative pressure.

 

Now if I’m somewhat successful in trapping this slurry in the vortex tank I can then design and add a second filtration tank or series of filter tanks which trap additional solids to further increase the water life. This second filtration system can be individual filters that can be opened or closed into the system to allow for filter removal and cleaning during operation. Or several big filters housed in one tank.  The ability to open and close these filters would perhaps allow a continuous operation as one filter is removed and cleaned (removing a percentage of solids from the water supply) the other(s) remains in operation.
 

I may be seeing this all wrong and end up with not much more than I already have. But I believe that it can be done. I don’t anticipate this system to provide clean, clear water (maybe in 10 or so years…) My goal is to manage and limit the suspended solids enough to run my highbanker for 100 + buckets on something like 80-100 gallons of water.
 

It’s getting late and I need to set up my base camp and start mining soon. I may just set up the 2nd gen system and start mining and work on the 3rd gen system as time allows.
 

Don’t get me wrong, I need your help. Keep the comments coming and don’t be shy telling me how and why it won’t work. Again, this site is much more sophisticated and knowledgeable than all the rest. There are many talented DIY people that are unaware of this forum. I will let them know…

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We run a recirk down here in the desserts of south Arizona using a 75 gallon horse trough just catching our tailings in a 5 gallon bucket. One goes in one comes out I run 50 buckets per day on 120 gallons of water using a 5hp trash pump. Gotta shovel out silt at lunch time and refill, dont notice too much sand in there though. Doing the recirk thing is a real pain in the butt except we average 1/3 oz a day or sometimes more  :ph34r:  :ph34r:  

Gotta love 1/3 oz per day... I might suggest that you install a tailing screen over the supply tub. It will eliminate 90% of the volume depending on the material you run. I use a SS 60 mesh screen and set it flat. Make it long enough to allow the tailings to sit and drip into the supply tank before removing. Just the tailing screen alone will increase the water life. And who likes packing water when you can be running material.

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I've actually had a lot of experience with cyclones, both for removing particulate matter (like sawdust) from air and solids (like sand) from water. They work great for separating coarse particles out of liquid or gas media, but they don't work to take tiny particles out. You cannot use a cyclone to take smoke out of air or clay out of water. The cyclone is just not the right tool to accomplish what you want to do. Its not just a little less efficient at doing what you want to do, its nearly 0 percent efficient.

 

Its like planning to cut a 2 x 4 in half not with a saw, but with a screwdriver. Its not that a screwdriver is a tool that is just a little less efficient than the proper one, its a tool that just wont do that job.

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I've actually had a lot of experience with cyclones, both for removing particulate matter (like sawdust) from air and solids (like sand) from water. They work great for separating coarse particles out of liquid or gas media, but they don't work to take tiny particles out. You cannot use a cyclone to take smoke out of air or clay out of water. The cyclone is just not the right tool to accomplish what you want to do. Its not just a little less efficient at doing what you want to do, its nearly 0 percent efficient.

 

Its like planning to cut a 2 x 4 in half not with a saw, but with a screwdriver. Its not that a screwdriver is a tool that is just a little less efficient than the proper one, its a tool that just wont do that job.small are these clay particles?

How small are these clay particles?

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How small are these clay particles?

 

 Boy... it has been 20 yrs since I did research on settleable solids and turbidity, but if I remember correctly

particles of 0.063mm (250 mesh) and smaller were the major factors in turbidity. You might say the

"unsettleable solids", that remain in suspension for looong periods of time.

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 Boy... it has been 20 yrs since I did research on settleable solids and turbidity, but if I remember correctly

particles of 0.063 (250 mesh) and smaller were the major factors in turbidity. You might say the

"unsettleable solids", that remain in suspension for looong periods of time.

So we're talking about 50-60 microns right? If so, then let say a valve manifold with 3 -50 (perhaps 20) micron filters with an approximate area of 100SF each would trap a lot of these particles. The reason for the vortex tank is to trap a larger range of particles before the filters; something like 59 to perhaps 150 mesh size particles which would reduce the filters runtime by unnecessarily plugging the filter. I agree that the most difficult aspect is to trap the small stuff, so I first trap the easy stuff with the vortex and then work on the small and really small stuff. I see this endeavor as a series of steps or in miner terms; classification. The tailing screen takes care of 90% of the material. The vortex needs to trap another percentage or size of particles so the effort to collect the small stuff is as efficient as can be; as it is the most difficult. This is going to take time and research. I know it can be done for something like $20K and very heavy equipment but that is not an option for me and many others. So we'll discuss, think, test and learn.

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 I would say 40-50 micron is the range you are looking at.

 For a small setup like yours filtering may be practical, if

you can get enough filter surface area to keep up with your

recycling requirement. Likely be quite a struggle keeping

those filters cleaned.

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Both clays and silts will cause you viscosity problems.

Geologists and soil scientists usually consider the dividing line separating clays from silts to occur at a particle size of 2 µm (clays being finer or smaller than silts). Your problem is in particles that are generally smaller than 5000 mesh. See: http://en.wikipedia.org/wiki/Clay

 

Cyclones work because the mass of the particle is sufficient to throw it against the outer wall of the cyclone where it can be separated from the flow as a whole. Think of spinning something on the end of a rope - as the centrifugal force of the spinning water works, the particle is thrown against the wall. A 50 mesh sized particle may have enough mass to throw itself against the outside wall. A 5000 mesh particle does not -it will just swirl through the water and your collection efficiency will be near zero.

By the way, the thicker and more viscous the fluid you are processing, the harder it is to capture anything with the cyclone. Thick fluids require that particles must be larger to be to get thrown against the wall. If you try to process thick surupy water heavy with clay, it may take a 10 mesh particle before it can be thrown against the wall and captured. Think about just the settling due to gravity. If you have thin water and you put clean 50 mesh sand in, it will settle out in a few seconds. If you put that same sand into thick viscous clay-water mixture heavy enough that you dont want to use it in your sluice, it may take that same sand an hour to settle down to the bottom.

 

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Both clays and silts will cause you viscosity problems.

Geologists and soil scientists usually consider the dividing line separating clays from silts to occur at a particle size of 2 µm (clays being finer or smaller than silts). Your problem is in particles that are generally smaller than 5000 mesh. See: http://en.wikipedia.org/wiki/Clay

 

Cyclones work because the mass of the particle is sufficient to throw it against the outer wall of the cyclone where it can be separated from the flow as a whole. Think of spinning something on the end of a rope - as the centrifugal force of the spinning water works, the particle is thrown against the wall. A 50 mesh sized particle may have enough mass to throw itself against the outside wall. A 5000 mesh particle does not -it will just swirl through the water and your collection efficiency will be near zero.

By the way, the thicker and more viscous the fluid you are processing, the harder it is to capture anything with the cyclone. Thick fluids require that particles must be larger to be to get thrown against the wall. If you try to process thick surupy water heavy with clay, it may take a 10 mesh particle before it can be thrown against the wall and captured. Think about just the settling due to gravity. If you have thin water and you put clean 50 mesh sand in, it will settle out in a few seconds. If you put that same sand into thick viscous clay-water mixture heavy enough that you dont want to use it in your sluice, it may take that same sand an hour to settle down to the bottom.

 

I understand what you're saying and agree. However, If I run my gen2 system (no vortex or filters) I can get 30 or so buckets through the system before the water fails. How much longer will the water usefulness be with the vortex and filter system? This is my point. Maybe it is only a few more buckets, but I think it will be much more. The sucess of the system is based on how much more, not producing an endless supply of usable water. If I can reach 50+ buckets then I will consider it a sucess as this would cut my down time to clean and refill the system. For my operation that means I could go for 4-5 days between water changes vs 2-3. I also understand that as I continue to add material to the water supply the ratio of solids increases. The system will be more efficent in the beginning and become less capable of traping particles and supplying sufficent water flow due to the restrictive nature of the filtration. The ability to change out or clean the filters may further extend the water life, but I'm concerned that the concentration of solids at the point of changing out filters will reduce the new filters run time and might not be worth the time and additional cost. This is something that will need to tested.

 

Again, I appreciate your time and comments.

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How much longer will the water usefulness be with the vortex and filter system?

I guess I am not really explaining myself as to what zero percent capture efficiency really means when it comes to collecting clay with a cyclone. If you are getting around 30 buckets without the cyclone, I am figuring you will get about 30 buckets with the vortex cyclone. The exact number will depend on the particular material you process on that day - if it has a little more or less clay than average. You already have the cyclone and seem really fixed on doing this, so give it a run and see what happens - its always fun to try new things. I just would suggest not to put in a huge number of hours working on it until you give it some trial runs.

How do you decide when your water to just too thick to use?

 

The screen thing seems like a good idea to recapture as much of the water as possible and minimizing the drag out by the gravels. Where did you buy your 60 mesh screen, and how did you choose that size?

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Got the screen and other materials at http://www.mcmaster.com/#

 

I tested 80 &100 mesh and they had trouble passing clean water which created too much run off. The 60 worked the best for me. However, you can't pitch the tailing screen enough to allow tailings to clear as the water just runs with the tailings. I run it flat and screed the tailings to the end allowing them to drip back into the supply tank.

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inclined plate water clarifiers...lamellas

to flow 20 gpm you need about 40 sq ft of inclined plates

 

 video on how they work

 

Images and links

 

using coroplast plastic sheet would be light and cheap , i recently paid $16 for a 4 x 8 sheet of 1/4"

 

Coroplast images and links


just a thought ...if you over watered this and gave up some water clarity it might seperate the heavies (black sand gold etc)

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A good concept and information. Not sure how it would fit onto the system or how it would handle the suspended clays. Segerating the sands is really not the issue and my wife takes care of seperating the gold from me or anything else... The videos got me caught up for about an hour. Good stuff.

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