Lost Password :: Posting Pictures :: Who's Online :: Stats :: Memberlist :: Top Posters :: Search
Alaska Gold Forum :: Alaska Prospecting Forum :: Fine Gold Sluice Design Help Needed
Unsubscribe From Newsletter

Welcome, Register :: Log In Welcome to our newest member, Placer_Pacer.

people online in the last 1 minutes - 0 members, 0 anon and 0 guests. (Most ever was 44 at 17:01:08 Tue Nov 20 2012)

Pages: [ 1 2 3 4 5 6 ]

[ Notify of replies made to this post ][ Print ][ Send To Friend ] [ Watch ] [ < ] [ > ]

LipCa
Offline
791 posts
Reply
Re: Fine Gold Sluice Design Help Needed ( 18:56:18 MonJan 16 2017 )

Yep, observing a different box.

  
dragline
Offline
671 posts

Reply
Re: Fine Gold Sluice Design Help Needed ( 23:11:24 MonJan 16 2017 )

Sorry guys, I've just returned from a long road trip to California and back.

Peluk, you reference very good and relevant comments and observations pertaining to beach gold sluice recovery methods and technologies. My immediate take-away from what you're saying is that for extremely fine gold such as is typically found on Nome or Oregon/California beaches you're probably going to have to screen down (a lot), minimize feed speed, minimize riffle height and, assumably, run at a very slow slurry velocity relative to more conventional (coarse gold) river and/or stream placers.

It will likely take me a few days to boil down and simplify my current designs to the point that you can see the problems that I am up against. But the fundamental concept I have going here for a multi-purpose gold sluice is that the riffles (areas where gold is recovered) operate completely subsurface. The actual physical characteristics of the riffles, mats or anything else pertaining to the recovery features of the sluice are irrelevant to the design. The only thing that really matters to me is the slurry velocity (i.e. feet per second) and my desire for relevant feedback for this metric prompted my posting this thread.

I trust that the concept of a subsurface high banker or beach sluice makes no sense and probably seems more like an oxymoron or joke to most of you than a legitimate concept. But this is the overall strategy that I have been working on and have been able to see conceptually thru to the point where I am generating design layouts for my first prototype.

Okay, now that we've got that out of the way I'm sure there are a hundred valid reasons why a subsurface beach or high banker sluice has almost a zero probability of actually working but hopefully I can get my prototype operational and then share the details here on the forum.

Imagine, if you will, a subsurface sluice such that there are multiple levels that double back underneath each other, sort of like a Gold Cube, except there is no air anywhere in the system, no boil box or undercurrent riffles, and the slope angle of each level is zero degrees (no slope, i.e. level).

With multiple courses at zero degrees the design is capable of achieving a very compact volume such that a 1 foot cube of sluice could theoretically double back under itself 8 or 10 times thereby achieving a width of 1 foot and a combined length of 8 to 10 feet.

Anyways, I'll hopefully be able to explain better in a few days.

dragline
[1 edits; Last edit by dragline at 02:35:41 Tue Jan 17 2017]

  
dragline
Offline
671 posts

Reply
Re: Fine Gold Sluice Design Help Needed ( 15:45:55 TueJan 17 2017 )

Geowizard,

Very true. I didn't say that this was an underwater sluice, partly because my current designs involve something more akin to a hybrid between a subsurface (underwater) sluice and the ubiquitous in-air sluice you see virtually everywhere. Since my current efforts involve a sluice meant to be operated on land and potentially replace any conventional sluice it would be somewhat misleading of me to call it an underwater sluice. Frankly, I'm not entirely sure what to call it.

I remember back in the late 1960's sometime Keene Engineering was manufacturing and selling a "subsurface sluice" that was close to worthless, from the reports I have heard from a few miners that actually used it. Even in Keene's description of this sluice they indicated it wasn't meant as a primary recovery sluice but was more intended as an overburden sluice. Because Keene's subsurface sluice was intended to be operated underwater and in line with the suction hose it was extremely vulnerable to tilting out of level and thereby dumping whatever gold that had been recovered to tails.

My current subsurface sluice design efforts, on the other hand, do not involve the sluice being operated underwater, but instead being operated on land just like any conventional sluice. The main difference between my current design and a conventional high banker sluice is that once the classified materials enter the sluice and riffle areas there will be no air anywhere until tails.

That's why I was hoping to get some feedback on slurry velocity here from the forum's members (not much luck with that so far) so I could design the thing to be able to accommodate a large range of different types of gold from extremely fine beach gold to coarse placer gold. As long as the material entering the subsurface zones of the sluice are highly classified down to 1/8 inch or smaller the same exact mechanical set up should be adjustable to operate at a wide variety of slurry velocities thereby allowing high efficiency, but lower productivity for fine beach gold, or, somewhat lower efficiency but much higher productivity for coarser gold.

That's the overall concept at least and that's why I hope you can appreciate that the riffle or mat types that are employed internally really do not matter that much because those types of details can be swapped out and optimized later on after I get the overall strategy functioning according to plan.

If this concept actually works, it will have several advantages (as well as a few disadvantages) relative to conventional in-air sluices.

Potential Advantages:

1. By doubling back underneath itself at zero slope (level) the design will allow multiple riffle courses to form a very compact (in terms of volume) overall sluice design.

2. Another advantage (for which I'm sure I'll get some argument here) is that this subsurface sluice will potentially allow a much greater slurry depth thereby achieving higher productivity for a given sluice width. The argument that might be made against this advantage is that by increasing the slurry depth one would also be increasing the settling time for the finest gold. While this is true most sluices when set up optimally will capture the vast majority of fines very close to the top of the sluice and the main reason why fines are captured after migrating further down the sluice is due to turbulence, something this subsurface sluice may be able to significantly reduce.

3. There will be reduced slurry turbulence owing to the elimination of wave resonances at the slurry to air interface present with a conventional sluice. With reduced slurry turbulence the fine gold settling time increases and the rate of capture of fine gold at the slurry to eddy interface also increases allowing fines to be more efficiently captured closer to the top of the sluice.

dragline

  
dragline
Offline
671 posts

Reply
Re: Fine Gold Sluice Design Help Needed ( 06:09:10 FriJan 20 2017 )

Here below is an image of the subsurface sluice design layout I have been working on. There are novel and proprietary design elements here that may be patented and I am hoping to file a provisional patent application soon. Even though I am making these designs public I retain all intellectual property rights implied herein.

This first image probably won't be clear until you click on the first image (980x823 pixels) to get a larger image. Then maximize your window and click a second time to see the native image in another window (larger full size graphic is 1904x1611 pixels).

Notice the position of the static water level. By opening or closing the sluice gate the static water level can be adjusted higher or lower depending upon input gallons per minute.

This specific layout is designed to achieve a slurry velocity across the riffles at 3 feet per second at 100 gallons per minute thru the input. However, as ore is loaded into the hopper and the slurry solids ratio increases the slurry velocity also increases. For example, suppose that 100 gallons per minute clear water is entering the input. You then feed another 50 gallons per minute ore solids into the hopper. Assuming the slurry volume has increased by another 50% with the added solids the slurry velocity across the riffles will increase to 4.5 feet per second.

I hope that you all here can understand why I was interested in hearing any feedback pertaining to slurry velocity that the members of this forum might have to offer. While I have not as yet received any feedback from the members, in terms of or pertaining to slurry velocity as expressed in actual numbers (feet per second), I would appreciate your feedback regarding this design.

While this specific design is intended for use as a highbanker sluice, consider also that this same design, in principle, might also be used as a dredge sluice (3 inch in this example). However it would be necessary that the dredge nozzle was capable of screening down to 1/2 inch or smaller so as to reduce the likelihood of rock jambs.

Don't ask me how clean-up is going to work. I've got a few ideas I'm working on but nothing rock solid yet.

If you're wondering what prevents the input water from filling up and overflowing over the rim of the hopper, consider the rapidly moving input water under the punch plate will create negative pressure (venturi effect) in the hopper pulling down additional water from the hopper and sending it to tails. That is why the sluice gate is necessary so as to create a balance between atmospheric pressure and the effective head of the slurry/water charging thru the system.


  
LipCa
Offline
791 posts
Reply
Re: Fine Gold Sluice Design Help Needed ( 07:30:06 FriJan 20 2017 )

Did you mean to date that drawing 18-Jan-2017, not 18-Jan-2016?

Looks like it will fill to the top with material.... Nothing to force the material through the "underwater sluice".

Won't the water introduced just rise through the punchplate?

Just my quick observation.....

  
dragline
Offline
671 posts

Reply
Re: Fine Gold Sluice Design Help Needed ( 16:14:02 FriJan 20 2017 )

LipCa,

Thanks for catching that oversight regarding the year (2016 should have been 2017). I have made the correction although you'll probably need to refresh your web browser's cache for those images to see the corrected images.

I understand what you're thinking about the feed thru the punch plate possibly being an issue. It would be somewhat involved for me to explain how this works but I do my best.

Your question: Looks like it will fill to the top with material. Nothing to force the material through the "underwater sluice". Won't the water introduced just rise through the punchplate?

My answer:

This is exactly the question I was expecting and hoping for and I appreciate your asking. Imagine that you have filled the hopper with classified materials. In this example let us believe that the hopper is filled with sand. Let us further imagine that the sluice gate is closed such that the entire 100 gal/min flow from the input flange is forced into the closed system. There is only one least path of resistance out of this closed system and that is up thru the punch plate filling up the hopper and overflowing over the rim within a few seconds. Perhaps this condition is similar to what your imagining might be the situation here. However, consider that the 100 gal/min flowing out of the input flange into the hopper will be traveling at a velocity of 5.4 ft/s.
23100/(Pi*((3-0.25)/2)^2)/(12*60)=5.4 ft/s

Now imagine that the sluice gate is fully open and the 5.4 ft/s flow from the input flange is allowed to flow directly down towards the riffle intake at the end underneath the punch plate. Some of that flow will force water thru that opening, across the riffles and out to tails. As this flow to tails proceeds it will create a negative pressure in the hopper owing to the venturi effect...



http://en.wikipedia.org/wiki/Venturi_effect

...caused when the rapidly flowing water underneath those holes draws water thru those holes and into the riffles intake. In my opinion, the main problem won't be due to the input clear water flowing up thru the punch plate and filling up the hopper. The problem will be the static water level in the hopper being sucked down to tails and when all that water is drained air will begin to be sucked down as well contaminating the riffles zone.

However, the dynamics of this venturi effect across the central area beneath the hopper punch plate will be offset by back current eddies towards the sides of the punch plate where a positive pressure from below will push clear water into the hopper. This positive pressure and flow of water into the underside of the hopper will liquefy the hopper contents thereby allowing the central negative pressure regions to suck hopper contents thru the punch plate and into the sluice.

Here is another mental exercise that hopefully illustrates my thinking concerning this issue. Imagine that the punch plate open area was just 1%, not the 40% that I arbitrarily chose. Given that the total punch plate area is about 116 square inches you would have an open area of 1.16 square inches thru the punch plate and into the hopper. Since the clear aperture area of the sluice opening at the end of the hopper is 10.69 square inches you would think that the vast majority of the 100 gal/min input would be flowing to tails. But even 1.16 square inches flowing into the hopper will fill up the hopper and eventually overflow at some point. But imagine if the hopper depth were 10 feet (absurd, I realize) the head in the hopper would be too great for the hopper to fill completely and overflow so all flow would be to tails.

Consider that at some open area percentage (as yet to be determined) the venturi effect will balance out the head in the hopper and a consistent water level in the hopper will be achieved. Theoretically, I could have two punch plates sandwiched together such that by sliding the holes across each other I could vary the open area percentage from zero to 40%. Should your concern about he hopper filling up and overflowing become a problem my adding this additional adjustment of the punch plate total open area might solve that problem. Or, it might not.

This problem is something I have thought a lot about and as well as potential solutions. In fact, even if the adjustable open area punch plates idea does not fully solve this problem I have other solutions not currently disclosed or illustrated that I can show you.

I have not yet shown a few additional features to this design concept that will be necessary for idiot proofing the actual use of this equipment and I will be happy to show some of those as my layouts progress.

I have chosen to build my prototype mostly out of plywood (with a waterproofing sealant coating) and as well as one side out of clear acrylic so as to allow visibility into the inner workings of the sluice riffles and flows. I figure the components will be easy enough to fabricate on my table saw and radial arm saw but eventually, should I actually get the problem solving completed with a fully functioning prototype build I will think about materials and designs more suitable for manufacturing.

Give me a few more days to work on my design layouts and I will hopefully be able to show you a different hopper, punch plate and sluice feed concept that might hopefully address these concerns. As design complexity increases so will material and manufacturing costs. But assuming I can get this concept and prototype to actually work I then worry about designs and materials optimized for low cost manufacturing.

dragline
[1 edits; Last edit by dragline at 16:36:35 Fri Jan 20 2017]

  
LipCa
Offline
791 posts
Reply
Re: Fine Gold Sluice Design Help Needed ( 19:03:13 FriJan 20 2017 )

"...caused when the rapidly flowing water underneath those holes draws water thru those holes and into the riffles intake."

How do you get the water to "rapidly flow" through when it has to get above its flow to exit?

Does it act as a siphon?

  
dragline
Offline
671 posts

Reply
Re: Fine Gold Sluice Design Help Needed ( 19:15:05 FriJan 20 2017 )

For my above example and calculations I chose an input of 100 gallons per minute (GPM) clear water arbitrarily. Here is an instance of a cheap Chinese trash pump that could probably push almost 200 GPM at full throttle thru this sluice as currently designed, theoretically.


7HP 3" Gasoline Trash Water Pump 16,000 GPH, 1/2" Max Solids Size
(for larger image right-click and choose "Open image in new tab")

...and here is an instance of a hose connections kit.


3" Trash Pump FCAM x MP Water Suction Hose Complete Kit w/25' Blue Discharge
(for larger image right-click and choose "Open image in new tab")

I've got the redesign of the hopper and punch plat figured out, and I've already had that design layout done for previous incarnations of this subsurface sluice concept effort. But given my other obligations and work schedule it will likely take me a few days to fit these efforts in and get a new layout generated that fits the current models.

But should you have questions, suggestions or comments feel free to post.

dragline

  
dragline
Offline
671 posts

Reply
Re: Fine Gold Sluice Design Help Needed ( 20:19:45 FriJan 20 2017 )

LipCa,

Your question: "How do you get the water to "rapidly flow" through when it has to get above its flow to exit? Does it act as a siphon?"

Regarding your concern about flowing upwards, then downwards in a closed system, and whether there is a siphon effect mitigating the energy necessary for the upward flow, yes, there is some trivial benefit to having the tails discharge below the input and no rise or fall inside a closed system matters. However, consider that the 7HP gasoline powered trash pump that I have specified for this system can achieve a maximum head of 90 feet, that's a maximum potential pressure of almost 40 PSI. When the sluice gate is open the effective pressure inside the system is almost zero in comparison so all such concerns may easily be ignored. The only thing in this regard that matters is that the vertical drop between the input and the output is about a foot which which will increase flow velocity very slightly.

Admittedly, this design is not optimal for maximal efficiency or at achieving high slurry densities transiting the sluice, which is my goal. But at least you should be able to get a rough idea of the challenges I'm up against creating a valid design layout, let alone a working prototype from these rough concepts.

dragline

  
dragline
Offline
671 posts

Reply
Re: Fine Gold Sluice Design Help Needed ( 23:14:21 SunJan 22 2017 )

Here are a few changes I was wanting to show you. A couple details that I do not illustrate involve the two adjustable elements:

1. There will be an adjustment knob, leaver,, screw, or whatever, accessible externally that will adjust the alignment of the holes in the two 10% open area punch plates such that one of the plates (the top as illustrated) will slide past the other thereby changing the net open area of the two combined punch plates between a maximum of 10% open area and a minimum of 0% open area. Of course it may be advantageous to limit the closed area to some nominal percentage, such as 2%, so as not to allow the system to become over pressurized if the venturi plate below is completely closed.

2. There will be an adjustment knob, leaver,, screw, or whatever, accessible externally that will adjust the tilt angle of the venturi plate pivoting about the illustrated piano hinge. This adjustment will increase or decrease the terminal venturi gap opening so as to regulate the pressure, up or down, in the area underneath the adjustable punch plates. By decreasing this venturi gap the pressure will increase causing increased flow thru the adjustable punch plates such that the multiple water jets pushing up thru the adjustable punch plate holes will force water jest thru the hopper basket punch plate and into the ore held inside the hopper basket. The flow of water into the basket will fluidize those materials causing them to flow down thru the basket punch plate and be sucked into the sluice.

Theoretically, as the venturi gap is decreased the slurry solids percentage will increase as will the water level in the hopper. Conversely, as the venturi gap is decreased the slurry solids ration will decrease and the water level in the hopper will also decrease.

There are a lot of fluid and hydrodynamic forces and actions taking place with this design that should not require too much explaining. But should you have questions, comments or suggestions feel free to post your response.


(Click to see enlarged image in new window, then click a second time in that new window to see the native image, quite large at 1852x1783 pixels)

  
polekaat
Offline
116 posts
Reply
Re: Fine Gold Sluice Design Help Needed ( 13:13:53 ThuJan 26 2017 )

I would love to see at least one side built out of plexi, so you could see the unit operating.
I have one concern, the 4" tailings discharge port, is this going to be a hose connection, or is it a 4" chute all the way across the sluice? If it's a hose connection, I can see tailings building up on each side of the "exit". If it's a chute, why not make it the same size as the last "downcomer", to maintain velocity, until the tailings are some distance away from the unit?

Trevor



---
We're all victims of our own gene pool. Apparently someone pee'd in yours. "Walter Bishop"
 
 
dragline
Offline
671 posts

Reply
Re: Fine Gold Sluice Design Help Needed ( 16:37:45 ThuJan 26 2017 )

polekaat,

Regarding your comment about building a prototype with plexi, sure, my goal all along was to use acrylic sheet for one or both sides so as to put some light and visibility on the internal workings of the thing during the testing phase of development.

Regarding your concern that there would be a build-up on the sides of a 4 inch hose at the tails end of the sluice, perhaps, but I'm not inclined to see that as a problem. Bear in mind that my design prototype here is only 6 inches wide (internal) with a 4 inch diameter tails discharge hose. This translates to about 1 inch on each side that isn't directly behind the 4 inch hose opening and while there could be some buildup in these regions the overall dead zones where buildup accumulates will be minuscule and it wouldn't be difficult for me to design a flat aluminum strip that pushes down to conform to the 4 inch diameter at the base and then out to the 6 inch sides higher up such that these dead-zones are eliminated.

Theoretically, this same design could have the internal width increased from 6 inches to 12, 24 or even 48 inches. The problem I have with larger widths is that the total gallons per minute required to run this type of sluice at the optimal slurry velocities (3 to 5 feet per second) becomes quite large. For this reason I chose to keep things narrow until such time as I have figured out how to build and operate a laboratory setup large enough to evaluate a wider prototypes with such gigantic flow requirements. This reminds me of the lab setup which G W Poling and J F Hamilton had at University of British Columbia, Department of Mining and Mineral Process Engineering back in 1986. If you have seen those videos you'll know how monstrous their setup was. G W Poling and J F Hamilton, Fine Gold Recovery of Selected Sluicebox Configurations, 1986

I've got a newer version of the design prototype I've completed that I'll be posting here soon that should hopefully illustrate how this subsurface sluice design concept can process so much greater volumes of materials with significantly reduced overall sluice size as compared to conventional sluices. How this design accomplishes this may be difficult for most placer miners to immediately see or understand but I am hopeful that I can get my message across with this next design prototype which incorporates a higher slurry profile of about 2.81 inches instead of the 1.78 inches with this last design. This subsurface design strategy allows for an almost unlimited increase in the slurry depth at fully controlled slurry velocities thereby increasing overall production capacity, something that would be impossible with a conventional in-air (above-surface) sluice.

  
dragline
Offline
671 posts

Reply
Re: Fine Gold Sluice Design Help Needed ( 18:49:44 ThuJan 26 2017 )

My latest design prototype that I may, or may not, move forward to testing follows. You'll hopefully notice the increase in the height of the sluice throat from 1.781" to 2.852" which represents roughly a 60% increase in slurry volume at any given slurry velocity. It isn't illustrated on this layout but given this slurry cross sectional area across the riffles, at a slurry velocity of 5 feet per second the slurry flow would be 262 gallons per minute. That's 15,720 gallons per hour or almost 78 cubic yards per hour from a sluice with overall dimensions measuring 7 inches wide and approximately 3 by 3 feet. If this sluice were 36 inches wide (internally) the productivity would be six times that or 468 cubic yards per hour from a sluice occupying a volume of about 1 cubic yard. At an average slurry solids ratio of 25% that'd be a processing capacity of 117 cubic yards of placer ore per hour.


Maximize your browsing window then click once to open a second window with a larger image. Click that second window again to see that larger image full size.

  
dragline
Offline
671 posts

Reply
Re: Fine Gold Sluice Design Help Needed ( 19:40:12 FriJan 27 2017 )

Geowizard,

I understand everything you are saying and I appreciate your opinion that there is nothing novel about my designs here. One thing that should be considered about patents is that not all novel designs or concepts are patent worthy. Therefore, you may be completely correct about there being nothing novel or patent worthy here. If this is the case I'd appreciate if you could please help me understand these things.

Q1: Does my design incorporate an Elutriation Column?

A1: I don't believe that it does because there is no separation of heavies taking place in this hopper. The hopper merely discharges all input except oversize materials. The only possible things novel that I can see about this hopper design is that (a) the hopper is filled with water, and, (b) all water added to the ore is fed from the underside, and (c), there is a uniform and constant area of ore in contact with the flowing water underneath and being jetted up thru a punch plate, and (d), there may be a benefit to having these features (a,b,c) working together such that the rate of discharge of the ore into the water supply may take place at a more uniform and constant rate than if the water were introduced into the system from above the ore . Admittedly, as a stand alone hopper these features might not be sufficiently novel to warrant a patent. Or, perhaps they might if this approach allows the generation of a slurry of higher and/or more uniform solids percentage than a convention water fed hopper. Nonetheless I would appreciate if you could find and post an illustration of a classifying hopper in which all water introduced into the hopper is jetted up thru a punch plate beneath the ore.

Q2: Is there nothing novel about a multiple water jet plenum supplying water to liquefy potentially dry ore from the underside thru a punch plate and simultaneously supply water pressure from that same plenum to a venturi that sucks classified ore from that hopper into a (sub-surface) sluice?

A2: The thing that appears novel here, in my opinion, is that there is one adjustment of the venturi flap that will increase flow thru the jets while simultaneously decreasing flow thru the suction venturi. Or, visa versa. This is one adjustment that when set optimally will balance of forces of water filling the hopper or evacuating the hopper. If what you say is true and there is nothing novel about this design I'd appreciate your posting some similar sluice design diagram that uses this feature.

Q3: Is there nothing novel about an in-air (not underwater) gold sluice where (a) ore is fed into an in-air hopper (not an underwater hopper), and (b) all riffles operate below the water surface with no air directly above them with level riffles (not sloping riffles) that fold back underneath each other?

A3: Please help me understand how you can say that these designs are not novel. Show me a design for a sluice operated in the air but with no air directly above level riffles folding underneath each other. Do this for me and I will greatly appreciate your efforts.

Thanks,

dragline




  
dragline
Offline
671 posts

Reply
Re: Fine Gold Sluice Design Help Needed ( 08:08:57 SatJan 28 2017 )

Geowizard,

I guess I was hoping for some feedback from some of the more technically inclined members of the forum here regarding what I believe are novel design elements with these subsurface sluice design layouts. Upon reflection, it seems that there is little to no interest from the forum here with engaging technical discussings of these elements.

You have been kind enough to give me a great deal of broad and general feedback, and I thank you for that. However, I was hoping for more targeted discussions concerning features of these designs that seem so obviously unusual to me, but apparently not so obvious to the members here.

If I may I will summarize what I believe to be your technical feedback concerning my designs so far....

#1. You are unable to see anything novel about my designs.
#2. According to you, designs on paper are imaginary until proven thru testing.
#3. You suggest that I build the thing, test it, and if it proves successful, then, and only then, will the the technical aspects of these designs merit evaluation or discussion.

Regarding your question about the column on the right, I am very glad you asked. You'll notice I have illustrated a static water level in this column at the point just before where the flow turns back down to the tails. This column and it raised overflow accomplishes several functions. The first function is to allow the system to charge full of water and never run out of water even when the flow from the input stops. When the system is fully charged to the top of the overflow in this column there will be a pool of static water in the hopper that provides a source of water for fluidizing the ore contents from below. Another function is to prevent air from flowing up thru the tails discharge and contaminating the subsurface riffles at times of low flow volume.

Perhaps I've bit off more than I can chew in bringing these designs to the forum here for discussion. I can imagine that from the perspective of almost anyone familiar with conventional sluice technologies these designs might seem overly complex and akin to a Rube Goldburg machine. At any rate, I appreciate your suggestion that I just go ahead and build it, which of course I am currently working on just that. But even if I were to build it, and test it, and it were to work as intended, I could still face the same problems of communicating how this thing works and why it provides many benefits over conventional sluices.

dragline

  
polekaat
Offline
116 posts
Reply
Re: Fine Gold Sluice Design Help Needed ( 13:16:27 MonJan 30 2017 )

Chuck,
I'm under the impression that his design was sealed, for underwater use, from the beginning (see the inlet on the left, and the lid, in his drawing. What I don't understand is, what purpose the punch plate, above the sluice, serves. If it's just for water level control, it could be eliminated, because the pressure of the pump/jet would overcome the vertical rise before the outlet. Also, the water level is shown, even with the top of the weir, which would actually be higher, and since it's a sealed box, would have to calculate the positive air pressure, at the top of the box, to determine actual level. My though is that it would work similar to a bazooka type underwater recovery system, but with more surface area to catch the gold. That's why he has been ok with such high velocity across his matting. If that's the case, I would use a design that incorporated a weir, like the gold cube uses, to centrifugally force the heavies to the bottom of the strata, before it runs across the matting.
I also think that the first (top) set of matting, would be better utilized on the "uphill" section, near the inlet. As designed, the first section of matting would only see water and fine lightweight material, that would/could flow up, through the 0%-10% variable punch plate.
As designed, he's showing almost ten feet of recovery area, in a compact package. I like the idea, just think that it needs some more CONSTRUCTIVE criticism.

Trevor
[2 edits; Last edit by polekaat at 13:31:20 Mon Jan 30 2017]



---
We're all victims of our own gene pool. Apparently someone pee'd in yours. "Walter Bishop"
 
 
polekaat
Offline
116 posts
Reply
Re: Fine Gold Sluice Design Help Needed ( 13:58:12 TueJan 31 2017 )

Chuck,

I believe that the easiest way to clean out this design, would be to have both sides removable. Sealing could be accomplished by cutting a channel in all surfaces making contact with the removable sides and inserting an o-ring into that channel. Then it could be secured with several threaded fasteners around the perimeter.
Instead of an inclined slick plate, as shown in the drawing, this area would be better utilized, with a grizzly, with a direct path out, for the oversized, or (as mentioned before) be covered with matting too.
To make a model/prototype, I'm thinking that an old computer case would be a great starting point. You'd only need to seal all the vent holes, add guides for the matting shelves, and work out some way to seal the removable sides. Not sturdy enough for production work, but a great platform for testing. Some even come with "windows" built into the sides, for observation. Hell, you could even utilize some waterproof, stick on, LED strips and a Lithium Polymer battery, to illuminate the inside, while in operation.
With the flows that you calculated, I'm concerned that the oversized material would have trouble, travelling up and over the "standpipe".

Trevor



---
We're all victims of our own gene pool. Apparently someone pee'd in yours. "Walter Bishop"
 
 
dragline
Offline
671 posts

Reply
Re: Fine Gold Sluice Design Help Needed ( 21:52:17 TueJan 31 2017 )

Alright, guys, I apologize for the delayed response... been a bit busier than usual at work.

Geowizard. Your calculations on flow velocity are roughly equivalent with my own calculations. Hopefully you can see why slurry flow velocity is so important with my efforts here to design a subsurface (Subby) sluice and why I was hoping for feedback here from miners that had made the effort to consider or measure slurry velocity. Unfortunately for me, the vast majority of placer miners have no compelling reason to think about slurry velocity or measure it when other variable such as sluice GPM and slope accomplish almost exactly the same thing.

I did buy a 7,250 GPH (121 GPM) sewage pump and Variac for setting up my design prototype lab. I'll be using this 2 inch pump to drive a venturi thru a 4 inch diameter pipe so that hopefully I'll be able to get three or four times the GPM at low heads. So, theoretically, my 121 GPM pump will push up to four times that amount, say, 400 GPM thru my prototype.



Left click to go to eBay listing where I
bought this pump, right click and select
"Open image in new tab" to see larger image.

Sewage pump, Stainless Steel Housing, 1 HP, 115V, 1 phase, 60 hz
Heavy duty, high flow and high lift.
Max lift (head) 49', Max 7250 GPH. Compatible to 2HP pump but use half of energy.
Heavy duty with high flow and high lift
Cast iron heavy duty impeller crushes hardest solids and lasts forever.
Include 20' power cable, electric plug, float Switch, optional hose adapter
Piggy Back Tether float switch included.
2" FNPT discharge. Include a 2" NPT to 2" optional adapter.
Hermetically sealed with stainless steel/Carbon-ceramic mechanical seal
Thermal protection to prevent overheating for longer life
High quality and high efficient UL approved motor, UL file No.: E233961
1 Year warranty for replacement parts.


Here is an image of the cast iron centrifugal impeller.


This pump isn't capable of developing a whole lot of head (pressure) and that's the main reason why it has such good flow volume at 1HP.


Right click and choose "Open image in new tab" to see larger image.

Because flow volume control is critical to the functionality of my design I've included a quick and dirty (magnetically dirty) speed control in the form of a Variac...


Yes, I understand that attempting to use a Variac for speed control of an AC motor is not optimal, but in some situations such as blowers and pumps it works, but obviously not as efficiently as a V/F controller (constant torque). I'm optimistic this will work for my needs but if it doesn't provide the full range of speed and flow control I require I can upgrade (by spending a whole lot more) to a V/F controller. See: Speed Control Methods Of Induction Motor

But Geowizard, I find it interesting that you brought up the analogy between a venturi system and flushing a toilet. I was about to bring up that same analogy should it have proven necessary so as to get my point across about how my Subby Sluice design actually works. It will probably be difficult for me to convince you about certain aspects of this design but suffice it to say there is no elutriation column working here because there is no separation of particles intended to take place anywhere other than the microeddies behind each riffle.

You might think that this system will fill up with sediments and become clogged but polekaat seems to understand how my design is intended to work in that it is an entirely pressurized system from supply to tails, but with a notable exception being the hopper. The question I hope to answer with my design is how you can introduce ore at atmospheric pressure into pressurized system. My solution to this problem involves an input hopper filled with water whereby the ore is liquefied and sucked down into the closed system in a completely controlled manner.

It does seem as though there is not a whole lot of designs out there for subsurface sluices. My Subby Sluice design is intended to operate out in the air rather than underwater. It is a challenging exercise in problem solving and not an effort guaranteed to succeed owing to the complexities involved with granting access to a sealed and pressurized system for the introduction of ore.

Perhaps the only way for me to communicate how this thing works is to build it, and assuming I can get it to work, let you see how it works with your own eyes.
[2 edits; Last edit by dragline at 21:58:16 Tue Jan 31 2017]

  
dragline
Offline
671 posts

Reply
Re: Fine Gold Sluice Design Help Needed ( 04:36:09 WedFeb 1 2017 )

Geowizard,

Yes, I understand your point completely. But please consider that if I succeed at my efforts to properly design and construct a prototype of this thing, and regulate all flow as required to make it work, the separation of materials according to density (in regions outside of the riffles) will not be factoring into the intended or unintended functionality of this system.

What you perceive to be an elutriation column is merely a standpipe (as Trevor so appropriately called it). Given a sufficiently classified ore going into the sluice and a sufficiently fast slurry velocity any difference in upward velocities between the lights and heavies traveling up this standpipe can be ignored since the design is intended to pass all materials entering the bottom of the standpipe over the weir and then down to tails. Once the system is operating at design parameters the vast majorities of heavies capable of being separated in this standpipe will have already been captured and retained in the riffles. Heavies such as excess mineral sands that enter the standpipe will quickly be raised over the weir and flow to tails as well.

You can call this standpipe an elutriation column if you want to but it is neither intended to be one nor will it function as one should my design efforts prove successful.

dragline
[1 edits; Last edit by dragline at 05:59:58 Wed Feb 1 2017]

  
dragline
Offline
671 posts

Reply
Re: Fine Gold Sluice Design Help Needed ( 05:14:29 WedFeb 1 2017 )

polekaat (Trevor),

I value your critical viewpoints because with your comments I can tell that you have developed a precursory basis for understanding my designs. I can confidently tell you that, with one possible exception, I will be able to address your concerns and show them to be invalid. But the fact that you are raising such reasonable and thoughtful concerns lets me know that we are getting closer to a mutual understanding.

Please allow me to respond to each of the concerns you have identified so far. If I am successful in communicating to you with my replies I am confident that you will develop more questions and concerns as we proceed to greater understanding of each other's views. Here are some of your comments with my replies...

Quote-01: I'm under the impression that his design was sealed, for underwater use, from the beginning (see the inlet on the left, and the lid, in his drawing.
Reply-01: No, not exactly. My Subby Sluice is not intended to be operated underwater. It is intended to be operated on land similarly to any other high banker sluice.

Quote-02: What I don't understand is, what purpose the punch plate, above the sluice, serves. If it's just for water level control, it could be eliminated, because the pressure of the pump/jet would overcome the vertical rise before the outlet.
Reply-02: The punch plate at the bottom of the hopper is affixed to a basket that inserts into the hopper. The punch plate serves three main functions. (1) The punch plate allows the miner to remove the hopper basket from the sluice hopper to a remote location (presumably a few feet away) and fill the hopper basket with pre-classified placer ore. Once the hopper basket is full of ore it can be slowly lowered into the sluice hopper. Bear in mind that the hopper will be partially full of water with water jets pushing upwards into the pool of water from below. With the hopper basket removed the pool of water in the sluice hopper will appear to be agitated like a turbulent jacuzzi. The full hopper basket should be lowered slowly into the hopper jacuzzi. If the heavy basket were to be dropped quickly it would cause a hydraulic pressure wave that would blast its way down thru the sluice across the riffles and risk dislodging the gold and concentrates that had already been sequestered there. As the basket is lowered into the jacuzzi pool the ore will quickly liquefy from the bottom upwards causing the placer ore to quickly fall thru the punch plate as the hydraulic jets force turbulent water up thru the 40% open area punch plate into the ore. This entire process of completely emptying the contents of the basket into the slurry flow should take a few seconds to less than a minute depending upon the percent open area of the punch plate and the flow pressure and volume of the venturi (jacuzzi) jets. (2) The punch plate serves to provide a 40% open area barrier so as to regulate the rate at which the ore is allowed to flow into the sluice intake, the top most sweeping 180 turn (yellow arrow) upper right. If the punch plate were not there and the ore were dumped into the hopper there could be a lot of problems. (a) Pressure wave each dump forced it way down the sluice as each shovel full of ore were dropped into the hopper jacuzzi pool. (b) Oversized materials will occasionally get into and clog the sluice. (c) Excessively high slurry solids percentages may cause the thru put of the system to slow down too much such that the hopper fills and overflows as the sluice intake is obstructed. (3) The 40% (as illustrated 1/8 inch) punch plate serves as a fail-safe barrier for the entry of oversized particles entering the system and allowing for such oversized particles to be captured and easily discarded before the hopper basket was refilled and loaded into the hopper.

Quote-03: Also, the water level is shown, even with the top of the weir, which would actually be higher, and since it's a sealed box, would have to calculate the positive air pressure, at the top of the box, to determine actual level.
Reply-03: Sorry, no. The water level illustrated in the in the weir (good name for that) is for reference only. This is not a dynamic level but only illustrated to get the point across that when the water flow entering the system is turned off the static water level will be as shown. It is important that this weir be there so as to always keep the system full of water. If the weir were not there the water would drain out when the pump was shut down which would not be a good thing (I'll be explaining the reasons for that later).

Quote-04: My thought is that it would work similar to a bazooka type underwater recovery system, but with more surface area to catch the gold.
Reply-04: Well, yes, that is definitely true about the increased riffle surface area but not so true in the since that the Bazooka is operated underwater with ore input from underwater whereas my Subby Sluice operates as a subsurface sluice on land with ore input from the atmosphere similarly in the role of a high banker.

Quote-05: That's why he has been ok with such high velocity across his matting. If that's the case, I would use a design that incorporated a weir, like the gold cube uses, to centrifugally force the heavies to the bottom of the strata, before it runs across the matting.
Reply-05: I am specifically NOT okay with high velocities over the riffles. That's definitely something I have been avoiding like the plague with these designs. I am only okay with very controllable slurry velocities across the riffles in the range of about 2 thru 5 feet per second. Theoretically one could run this system at ridiculously high slurry velocities but the only thing you would gain by doing so would be increased production capacity in terms of cubic yards of ore per hour. The problem is that the higher velocities will sacrifice fine gold recover efficiency. But assuming one were to only have an average of 20 mesh placer gold and nothing smaller than 40 mesh you might run this thing at close to 6 feet per second with the highest overall productive capacity. However, for a lot of operating conditions were there is a significant percentage of gold mesh sizes smaller then 40 mesh you would probably run this system optimally at slurry flow velocities of between 2 and 4 feet per second. Your point about the Gold Cube is completely irrelevant in this case because it would add absolutely no positive enhancement to the overall performance of this design since what you are actually talking about is undercurrent riffles or boil boxes or whatever, which are essentially miniature versions of this entire subsurface sluice. It might be extremely difficult to convince you about my point here since none of us have much of any prior experience or reference for understanding how a subsurface sluice like I am proposing might actually perform. Suffice it to say that I've thought a lot about the physics and hydraulic dynamics of multiple sets of completely subsurface riffles operating under highly controlled velocity conditions, to the tune of 8 linear feet of riffles with this illustration, and I am convinced that this system is capable of establishing greatly improved (that is much less) slurry turbulence as compared to P&S, Le Trap, or Gold Cube sluices such that nothing like an undercurrent riffle or boil box is going to add any significant performance enhancement to eight feet of riffles that are already completely subsurface. By incorporating such undercurrent riffle features into this design you would actually be reducing overall recovery efficiency.

Quote-06: I also think that the first (top) set of matting, would be better utilized on the "uphill" section, near the inlet. As designed, the first section of matting would only see water and fine lightweight material, that would/could flow up, through the 0%-10% variable punch plate.
Reply-06: Please allow me to explain. The design that you see is just one of many possible and similar configurations, each optimized for a specific type of operation. The design that you see illustrated is meant for use similar to that of a high banker sluice. In other words, the input water hose would supply water only, no ore whatsoever. All ore entering this high banker type sluice would be entering from the hopper. The only thing entering the input is a flow of clear water at a sufficient GPM to drive the hydrodynamic conditions necessary to make this thing work as intended. Also, I apologize that I have likely done a disservice to this design by calling the jet plate a 0% to 10% variable punch plate. I did that because it was something simple and quick to get the point across (apparently I failed to do that). I would appreciate if you might rather think of this as as water jet array. Imagine that these were not punch plates but were rather a plate with an array of nozzles aimed upwards and at a 20 angle inclined towards tails from vertical. There could be a second occluding plate beneath the jet-plate so as to occlude the flow thru a range of equivalent open areas. The purpose of these nozzles is to generate jacuzzi-like streams of water that force their way upwards and thru the 40% open area punch plate to liquefy the ore contents of the basket. The 20 forward tilt angle will cause the general direction of flow in the hopper to proceed towards the sluice intake on the right.

Quote-07: I believe that the easiest way to clean out this design, would be to have both sides removable. Sealing could be accomplished by cutting a channel in all surfaces making contact with the removable sides and inserting an o-ring into that channel. Then it could be secured with several threaded fasteners around the perimeter.
Reply-07: Cleaning out the system will actually a whole lot easier than that, i.e. no disassembly required. Because, as you say, this is overall a rather compact design it should not be that difficult to put handles and roll bars on it such that after the pump is shut down and the input and tails hoses are quick disconnected, the entire sluice while it remains sealed and full of water can be tilted to the sides or to the input side. After a few of these motions all of the relatively little volume of the concentrates (formerly held in the riffles) can be caused to settle down to the input side curved surfaces when the unit is tilted 90 on that (left) side. Then on one side of the input side (left or right doesn't matter) you would have plugs that are removed to drain out the water contents including concentrates. This would be an easy, simple and quick procedures that would take less than 5 minutes and the entire system could be back up, running and operational. But yes, the sides could be removable with a dozen (or likely a lot more) small diameter (#6 or #8 perhaps) threaded rods (or studs) poking thru each acrylic side plate such that the acrylic sheet would be contacting a neoprene gasket anywhere and everywhere necessary with the threaded rods providing key points of force keeping the sides in contact with and sealing the system. Bear in mind that the pressures here will be minimal but not ignorable such that the mechanical forces necessary to maintain a seal across all contact areas will be necessary. Because the system can be cleaned up without any disassembly the only occasions required for disassembly will be situations in which errant oversized objects have clogged the system or critical failures have occurred that require repair.

Quote-08: To make a model/prototype, I'm thinking that an old computer case would be a great starting point. You'd only need to seal all the vent holes, add guides for the matting shelves, and work out some way to seal the removable sides. Not sturdy enough for production work, but a great platform for testing. Some even come with "windows" built into the sides, for observation. Hell, you could even utilize some waterproof, stick on, LED strips and a Lithium Polymer battery, to illuminate the inside, while in operation.
Reply-08: I really like your super cool idea about using LED strips to illuminate the interior riffles. But perhaps that won't be necessary for my prototype since I'm planning on building an extremely narrow sluice, 6 inches wide as illustrated (or perhaps as narrow as 2 or 4 inches for the purposes of proof of concept), and if both of the sides were completely acrylic there were be plenty of light entering to see the happenings during operations. But in regards to the actual building materials, for the first prototype I was thinking plywood and Iron Board (a 5mm thick rigid wood laminate). Of course I'd have to completely paint them with clear water sealant so as to hopefully get some reasonable life expectancy from them.

Quote-09: With the flows that you calculated, I'm concerned that the oversized material would have trouble, travelling up and over the "standpipe".
Reply-08: You bring up a very good observation here. Of course for the purposes of the prototype this upward flowing "standpipe" is illustrated as the same dimensionally rectangular area as the sluice but it could just as easily be narrowed down to a round standpipe of lesser cross sectional area so as to increase the flow velocity. Bear in mind that there are absolutely no oversized materials permitted in this system. That is a very important rule that must be obeyed. For this system to function properly and efficiently there must be strict compliance to pre-classification and screening of materials to some upper limit. That upper limit on particle size could be 1/8 inch as illustrated, or it theoretically could be as much as 1/2 inch at some significantly higher slurry velocity. Consider the hydrodynamics involved here when you have a slurry moving at 2 feet per second and a maximum particle size of 1/8 inch. What is the settling velocity of a 1/8 inch diameter sphere of sg=3? Answer: Not much but probably less than 2 feet per second. However, iif I were to return the rectangular slurry area to a round standpipe before turning vertically after the sluice that 2 feet per second velocity might easily become 4 feet per second and well above than would be cause for concern.

Thanks again for your observations and comments. Hopefully I've been able to make some sense out of this design here. Consider also that if I were not designing a sub-surface high banking sluice there would be no need for a hopper and this entire system would be a hundred times easier to design and fabricate. Cleanup of such a system would also be a breeze. The reason I didn't tackle that project here for the purposes of discussion is because there would not be much of anything novel about such a system and I wanted to see how far I could push these discussions into more technical and previously unexplored conceptual realms.

Perhaps such a non-high-banker and more Bazooka-like Subby Sluice might be a considerably easier design concept for the forum to understand, find interest with and get behind. So perhaps I might build and test that prototype first... not sure yet.

I have other more considerably complex designs than this high-banker Subby Sluice that I would hope to be discussing and developing prototypes for eventually. But designs for such complex systems must proceed with slow and steady step by step design and development with prototypes validating each step along the way. In this regard this entire Subby High Banker Sluice design that you see here is but one cog in a much larger wheel of a complex systems in situ mining strategy that I have been giving thought to and periodically making effort towards designing for the more than a decade.

dragline
[1 edits; Last edit by dragline at 05:31:34 Wed Feb 1 2017]

  
polekaat
Offline
116 posts
Reply
Re: Fine Gold Sluice Design Help Needed ( 13:18:51 WedFeb 1 2017 )

Dragline,

This post will be short. I have to take my daughter to school. I will ponder this, and offer any new thought that I might have, later.
Thank you for the clarification. The whole precursor to all of my comments, so far, has been, that this design was for a dredge type system. This idea came from the name on your drawing, i.e. "subsurface sluice", which to me meant, underwater. Time for me to back up and punt!
I have been a piping/mechanical designer for almost 30 years. The last 10 years, I have been either, a section lead (I helped all of the project leads, when they ran into problems ), or the department head (I did all of the hiring/firing, and doled out work to teams that I assembled, and kept track of these projects).

Trevor



---
We're all victims of our own gene pool. Apparently someone pee'd in yours. "Walter Bishop"
 
 
dragline
Offline
671 posts

Reply
Re: Fine Gold Sluice Design Help Needed ( 16:33:12 WedFeb 1 2017 )

Trevor,

That's awesome that you have worked as a piping/mechanical designer for almost 30 years, and a project manager for 10 years.

I have similar experience as well. I started out as a mechanical designer working for GE Nuclear Products Division in 1974 and after about 10 years had worked my way up to associate mechanical engineer working in the semi-conductor processing equipment industry in Silicon Valley, California. My specialty was ultraviolet optical exposure systems for semi-conductor photo lithography and as well as some optical designs for defense department satellite systems.

I stopped doing the mechanical engineering work professionally in about 2006 (after about 30 years as well). I started out on velum, moved on to Autocad in 1984, and in 1999 migrated over to SolidWorks with Cosmos FEA. I assume you also use solid modeling software of some sort?

dragline
[1 edits; Last edit by dragline at 06:18:04 Thu Feb 2 2017]

  
dragline
Offline
671 posts

Reply
Re: Fine Gold Sluice Design Help Needed ( 17:17:51 WedFeb 1 2017 )

Geowizard,

Right. I understand and appreciate your comments and the confusion you are experiencing and expressing. Let's talk a little about terminology and semantics.

Sluice: What is a sluice? If we're talking about a high banker sluice the question might arise as to whether the grizzly is an integral and necessary part of the sluice. On the other hand we might question as to whether the sluice might be something that is a subcomponent of the larger assembly referred to as a high banker and residing underneath the grizzly. Referring to the part or subcomponent of the high banker that primarily incorporates riffles and sits underneath the grizzly as a sluice seems appropriate. Likewise referring to the grizzly as a subcomponent of the high banker may also be appropriate depending upon the circumstances. If you find it confusing or inappropriate with my use of word "sluice" in referring to a subcomponent of larger assembly then I apologize for not clarifying these relationships in the context of my descriptions. In the case of my design, however, you might consider that I have no grizzly depicted but I do have a different component depicted, that of the hopper. Some confusion likely also arises with my use of the word "hopper" because one might immediately infer that a grizzly lies immediately below this hopper but such is not the case. The hopper in my designs is meant to accept the output of either a grizzly or a hopper basket such that my illustrated hopper might actually be the second hopper in a larger and unseen assembly. The fact that this entire assembly that includes a subsurface sluice is not located underwater but the riffles and the sluice subcomponent are located subsurface and underwater might seem confusing and contradictory to you. But the presence of these seeming contradictions only arise owing to the challenges involved with understanding novel design layouts described with words and semantics with potentially ambiguous inferences.

Underwater: This word may be used to describe an entire assembly of components that include a sluice. Or, this word may be used to describe a subcomponent of a larger assembly. If I have used this same word in both these instances without clarifying the specific conditions or context involved I apologize for any confusion this may have caused.

Subsurface: Likewise the use of this word may ambiguously refer to two different types of water surfaces. One might infer that the water surface in question might be the surface of the ocean, river, lake, stream or hot tub. Or, the surface in question might be the water surface in the hopper subcomponent of my designs. This later use is that with which my design avails.

Therefore, it should be apparently obvious, subsequent to this explanation, that my use of the words "underwater" or "subsurface" may have two different uses.
1. These words may be used in the context of my entire assembly. I believe that I have not, in this forum thread at least, used these words in this context.
2. These words are used specifically in the context of the sluice as a subcomponent of the larger assembly, I believe that, perhaps with only one or two exceptions, has been my use of these words specific to this subcomponent context.

Thank you for calling my attention to these confusing concerns.

dragline

[2 edits; Last edit by dragline at 17:53:03 Wed Feb 1 2017]

  
Fleng
Offline
147 posts

Reply
Re: Fine Gold Sluice Design Help Needed ( 18:29:35 ThuFeb 2 2017 )

Some good discussion here, thought I'd offer something.

As far as using a variac to fine tune the flow from the pump- this is probably not the best approach. While you correctly cited the HP/flow chart for the impeller- the voltage/power relationship is highly nonlinear. From my textbook on rotating electrical machines:

"Since the breakdown torque is proportional to the square of the voltage, reducing the voltage may stall the motor so that voltage speed control is rarely used."

In an example a full load motor was operated at half power and the synchronous speed was reduced by slightly less than 3%.

The more common method to vary speed in an AC motor is to vary the voltage in the rotor only. Because the rotational speed depends upon number of poles, line frequency, line voltage, and rotor resistance, a limited number of options are available. A pump motor is optimized for a set of fixed conditions. When those conditions are varied-unintended circumstances can arise.

In your case, tuning of the water flow would be more useful by diverting or restricting the output. Normally I would favor the trash pump for the application but in this case the more common method of dredging with a fresh water pump would allow the use of a diversion valve to get a full range of supply water. Also far cheaper and safer than a variac!

The other question I had is in regard to the punch plate. It looks like the incline below it would fill up with sediment and eventually be too clogged to be a factor.

  
dragline
Offline
671 posts

Reply
Re: Fine Gold Sluice Design Help Needed ( 21:21:42 ThuFeb 2 2017 )

Fleng,

You are absolutely correct that the use of a Variac to control the speed and in turn vary the output of an AC motor driven pump is not optimal. I knew that and referred to those concerns in my previous post. The best method for controlling an AC induction motor involves the maintenance of constant torque which can be accomplished with V/F Controller, i.e. a controller that varies the voltage and the frequency (starting at 60 Hz and dropping lower) in unison such that the ratio of voltage and frequency remain constant. But I like your suggestion about varying the rotor voltage only. I'll see if I can do that with this pump, although it comes as a hermetically sealed unit and gaining access to the rotor connections independently may not be practical.

When you refer to the problem of a Variac dropping the voltage to the point where the motor stalls, this is often the case where the mechanical demands upon the motor are not linear. But in the case of the centrifugal impeller pump this situation is the opposite such that the force necessary to spin the impeller falls linearly with the speed of the motor. While using a Variac to vary the output of such a pump is not ideal it will not usually cause the motor to stall until the speed falls to between 40% and 50% of nominal.

Suffice it to say that for this specific pump and motor the Variac should work over a somewhat limited dynamic range, i.e. I'll probably only be able to use the Variac to cut the flow down to 40% of optimal. But as you are probably aware, V/F Controllers are quite pricey compared to a Variac for the same motor. Whereas this 30 Amp Variac cost about $115 (with free shipping) the cost of a 30 Amp V/F Controller would probably run me closer to $400 or more depending upon whether I could find a compatible used controller.

Of course I also appreciate your suggestion about incorporating a mechanical (plumbing) diverter valve. This actually might be an even better option than controlling the speed of the AC motor, now that I think about the possibilities here. I didn't get into the specifics previously but I did mention that I was planning on using the output of the 2 inch diameter trash pump to supply a venturi that provided the main supply for the Subby Sluice. The way this might work with your diverter valve suggestion could be that the 2 inch output of the pump would supply a 1.5 inch venturi inside a 4 inch supply pipe. Then by adding a 4 inch ball valve onto the the 4 inch supply pipe the restriction could thereby vary the resulting output of the venturi system. Perhaps something like this...


Click to open larger image in new window.

Thanks for the suggestions.

dragline
[1 edits; Last edit by dragline at 16:25:34 Fri Feb 3 2017]

  
Fleng
Offline
147 posts

Reply
Re: Fine Gold Sluice Design Help Needed ( 17:38:39 FriFeb 3 2017 )

dragline:
As I look at the design (quick work BTW) the only issue I see is that the ball valve restrictor may clog. A recurring theme of this project is that the ore has to be separated down to mesh 2 at least. Since we are talking fine gold this is the target product. Knowing that gravel is the most common medium where gold is found-separating the larger rock is a nontrivial process.

Wear and tear is something that should be considered as well. A gravel slurry is going to wear down whatever it touches. In the proof of concept stage it isn't an issue yet. Implementation in the field will. Painted plywood sounds like a semi-permanent solution but painted plywood with a stainless steel sheet metal liner would be a more robust solution. Handles on the sheet metal also makes for a quick rinse clean out.

  
dragline
Offline
671 posts

Reply
Re: Fine Gold Sluice Design Help Needed ( 17:47:23 FriFeb 3 2017 )

I apologize. I have come to the conclusion that I have done the forum members here a disservice. I have made a mistake with my assumption that I was adequately illustrating and describing my subsurface sluice designs here in this thread. It seems apparent now that I have caused somewhat of a cognitive dissonance among some of the members here. Let me explain.

Question: When was the last time you saw a subsurface sluice operate in the air and on land?

For anyone familiar with subsurface sluices answering this question might require overcoming some confusion involving a seeming contradiction. One might think that subsurface sluices, by definition, operate under the surface of the water. While this assumption is completely true the question might arise as to what type of water surface is necessary to fulfill this condition (see my previous post).

My reasons for presenting these subsurface sluice designs to this forum involve my belief and conviction that a subsurface sluice may present a variety of instances of superior performance relative to a conventional atmospheric sluice. But it is challenging to figure out words and terminologies that adequately describe and convey the design principles involved, hence my question above. If you haven't seen or even thought about the possibility of a subsurface sluice that is operated in the atmosphere and on land you might be challenged to understand what these designs are describing.

What might we call such a subsurface sluice that is operated in the atmosphere and on land?

How about if I name my atmospheric subsurface sluice the "Land Shark Sluice." While these words don't seem to describe anything like a atmospheric subsurface sluice, these words do in fact convey and impart the cognitive dissonance that many miners might experience when presented with oxymoronic descriptors. Perhaps I should call this subsurface sluice an "Alien Sluice" or something equally bizarre because there seems to be little if any frame of reference with which the vast majority of miners might categorize such a thing. If I am wrong and there are such things as atmospheric subsurface sluices in use today, or there are words commonly used to describe such things, please enlighten me. Otherwise, I'll continue to think it is reasonable to believe that there is a likelihood that these concepts and designs are at least in some respects novel.

  
dragline
Offline
671 posts

Reply
Re: Fine Gold Sluice Design Help Needed ( 18:29:22 FriFeb 3 2017 )

Fleng,

As you say, while presenting designs and illustrations for prototypical project development I will ignore such details as the incorporation of classification hardware since it will be an easy matter for me to presreen and exclude all materials larger than 1/8 inch. I do not believe it would be practical or appropriate for me to worry about such matters at this stage of the design development since doing so might significantly complicate and increase the cost and design time involved in going to testing. The incorporation of such things as classification and stainless steel lined plywood are not essential in any way to the determination of the "proof of concept" that you so appropriately mention.

I have mentioned this previously, but please understand that the ball valve you see in this most recent illustration will be accepting clear to turbid water only, i.e. no particulates whatsoever larger than silt will enter thru this ball valve because the placer ore is intended to be introduced into the hopper and in turn be injected into the subsurface sluice via the main hydraulic venturi illustrated with the main layout. Further, the water entering thru the ball valve is merely the water supply necessary to drive the various venturies of these systems and also to supply the entirety of the water necessary to liquefy the placer ore placed into the hopper into a slurry that manifests the desired range of solids percentages.

Therefore I am not worried about solids clogging this ball valve. If I were to attempt to design a subsurface (Land Shark) sluice whereby the ore solids were entering the system from the region of the ball valve there would be absolutely no reason for the ball valve. Please recognize that this design is a sluice that would be similar in function to a high banker, not a dredge.

Likewise as I have previously mentioned, designing a subsurface atmospheric sluice that would service a dredge would be a hundred times easier than the high banker version you see described. Because everyone here seems to be having so much trouble grasping the concepts involved with this first design I'm thinking it might be more appropriate to place these high banker subsurface sluice designs on the shelf, for the time being, and focus my design efforts on concepts that would be significantly easier for the forum members to understand. The prototype designs and construction of such a dredging subsurface atmospheric sluice would also be immensely easier.

Please allow me a few days to think about and perhaps develop a strategy for this simpler dredging subsurface sluice and I'll hopefully be able to post illustrations along that theme.

dragline

  
dragline
Offline
671 posts

Reply
Re: Fine Gold Sluice Design Help Needed ( 02:18:47 SatFeb 4 2017 )

Geowizard,

Yes, your notations seem to really help the flow of understanding how these various areas interact. I really appreciate your making that effort. I can tell from your notations that you understand the principles and functionality of this Subby Sluice almost completely. Here is my attempt at a similar notational diagram...



1. An external water pump (not shown) is connected to an appropriate 4 inch diameter quick connect fitting (not shown) at inlet (A).

2. Water flow from inlet (A) pressurizes Plenum (B) so as to cause water flow thru Multiple Jets (C) and Main Venturi (D).

3. Water flow thru multiple adjustable jets (C) forces thru hopper basket 40% open area punch plate (E) to fluidize the solids content of hopper basket (G).

4. Adjustable gap venturi (D) functions to increase or decrease water pressure in plenum (B) and also to regulate water flow passing thru venturi (D) so as to increase or decrease suction (negative pressure) upon the water and solids content in the region bounded above multiple jets (C) and below hopper basket punch plate (E).

5. The 40% open area hopper basket punch plate (E) serves to regulate the flow of the solids content of hopper basket (G) into the sluice.

6. With water flow thru inlet (A) and while plenum (B) is pressurized the multiple jets (C) will cause hydraulically active jets to force thru basket 40% open area punch plate (E) thereby fluidizing the solids content of the hopper basket. The adjustable water level (F) within the hopper and hopper basket serves to fully wet and saturate the solids content of the hopper basket (G) allowing rapid fluidization of solids content to occur.

7. The hopper basket (G) when removed from hopper may be placed remotely where placer ores may be loaded within the basket while hopper basket punch plate (E) serves to retain dry or damp placer ores during filling and subsequent transport back to the hopper filled with water to level (F). As the hopper basket is lowered into and thru water level (F) the contents quickly fluidize falling under the influence of gravity thru 40% open area hopper basket punch plate (E). In addition to the forces of gravity the hopper basket solids are sucked down thru 40% open area punch plate (E) into the sluice riffles (I) under the influence of the suction power introduced into the sluice riffles from main venturi (D).

8. The hopper basket (G) has an opening (H) across the full region of the top that serves to accept placer ore while the basket is installed within or remote to the hopper.

9. Once the hopper basket (G) is filled with ore solids and place in hopper water (F) and water jets (C) have fluidized the hopper basket solids the suction caused by main venturi (D) will draw down the water and slurry solids from above the water jets (C) down into and pass thru the multiple levels of subsurface sluice riffles (I) where denser constituent particles such as gold, minerals sands and other dense materials will become sequestered within the eddies of the subsurface sluice riffles.

10. After the denser materials have been removed from the slurry and retained in the riffles (I) the slurry then proceeds up standpipe (J).

11. Upon reaching the top of the standpipe (J) the slurry doubles back down towards the tails output (L) where an unseen 4 inch diameter quick connect fitting attaches to a hose or pipe for transporting the tails to areas distant to the sluice operations area.

12. The purpose of the weir (K) located at the top of standpipe (J) is to prevent the water contents of the sluice from draining to tails such that the riffles (I) are always filled with water, even when the pump is turned off, and air is not allowed to enter the riffles regions (I) so that the riffles can always remain subsurface of water level (F)..

Of course this verbiage above is long ways from that you might expect to see accompany US Patents, but hopefully this diagram might help the members here better understand how this thing is intended to work.

Thanks for your help.

dragline

  
dragline
Offline
671 posts

Reply
Re: Fine Gold Sluice Design Help Needed ( 02:48:58 SatFeb 4 2017 )

The next logical enhancement I can envision that will increase the functionality and performance of this design would be to incorporate a mechanically actuated float that reciprocally changes the adjustments for the flow of water thru the multiple venturi jets (C) and the gap opening of the main venturi (D).

The way I envision the functionality of this float is such that when the water level (F) is higher than optimal the float will rise thereby mechanically causing the flow thru the multiple venturi jets to decrease while simultaneously the gap and flow thru main venturi (D) will increase.

Conversely, when the water level (F) is lower than optimal the float in hopper (G) will fall causing the decrease in the opening of the main venturi gap (D) while simultaneously causing the flow thru the multiple jets to increase.

Theoretically all three components will be manually adjustable so as to optimize performance.
1. Hopper basket float will be manually adjustable in height so as to set the water level (F) to a specific height in the hopper basket (G).
2. Multiple venturi jets (C) will be manually adjustable so as to set the optimal upward flow thru the hopper basket punch plate (E) while maintaining sufficient plenum (B) pressure to adequately supply flow to main venturi (D).
3. Main venturi (D) will be manually adjustable so as to likewise balance the forces of plenum (B) pressure and multiple water jets (C).

Once all three of these manual adjustments have been set the float will take over the automatic adjustments of the multiple water jets (C) and the main venturi gap (D).

These adjustments will likely need to be reset to different positions if there is a significant change in water flow thru input (A). Increasing or decreasing the flow thru input (A) will have the effect of increasing or decreasing the slurry velocity across the riffles (I) such that the over all productivity of the sluice in terms of cubic yards per hour will be increased or decreased accordingly.

Of course increasing the rate of water flow thru input (A) will decrease the efficiency of this design at capturing smaller particulate sized gold and heavies but will increase overall performance for larger particulate sized gold. Conversely, decreasing the water flow thru input (A) will increase the efficiency of fine gold capture wile decreasing the overall productivity of coarse gold capture. At some optimal balance of slurry flow velocity, fine gold retention efficiency and coarse gold production volume the miner should be able to dial in their best overall performance with this design.

dragline

  

Pages: [ 1 2 3 4 5 6 ]

[ Notify of replies made to this post ][ Print ][ Send To Friend ] [ Watch ] [ < ] [ > ]

 Total Members: 11931

  • Can't start a new thread. (Everyone Registered)
  • Can't start a new poll. (Mods & Admins)
  • Can't add a reply. (Everyone Registered)
  • Can't edit your posts.(Everyone Registered)
  • Register :: Log In :: Administrators

    The time is now 13:31:28 Tue Oct 17 2017

    Powered By BbBoard V1.4.2
    © 2001-2007 BbBoy.net
    Alaska Gold Forum :: Alaska Prospecting Forum :: Fine Gold Sluice Design Help Needed

    [Most Recent Quotes from www.kitco.com]

    [Most Recent Quotes from www.kitco.com]