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dragline
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Re: Fine Gold Sluice Design Help Needed ( 04:41:54 SatFeb 4 2017 )

Geowizard,

I guess I'm going to have take a moment and explain a little about fluid dynamics and how these forces are involved with this design. It is completely understandable why you might have said what you did because it is likely that you do not see what I see because I have failed to communicate certain aspects and details of this design to you. But please consider that your following statements in the context of this design are completely false:

"Because water is not compressible, the pressure is the same everywhere in the container. The only pressure differential is from top to bottom because of the weight of the water. That weight is 0.4 pounds per vertical foot."

I apologize that I do not know your level of education, but you might recall learning that anytime you have a gas or liquid moving at one velocity relative to another at some other velocity there will be a pressure differential between those flows.

This is how venturies work, toilets flush and airplanes achieve lift and fly. When I mention to you that plenum (B) becomes pressurized it does so because the water flowing into the plenum thru a 4 inch diameter area then charges that plenum to a pressure higher than the volumes surrounding outlets owing to the fact that the sum total of all the outlet areas from plenum (B) is significantly smaller than the input area. Because of these outlet area restrictions a virtual head (pressure) is created upon the pump such that the pump has increased work.

The sum total of all outlet areas must be significantly smaller than input area so as to establish the pressure differential necessary to drive the various venturi outlets under pressure at high velocities so as to perform the needed work. There are two different output areas from the plenum, each with separately adjustable total open areas.

The multiple venturi array (C) receives the higher plenum pressure and water flows thru those multiple venturies at a high velocity into the slower lower pressure area surrounding the 40% open area hopper basket punch plate (E).

Likewise, the main sluice venturi receives the higher pressure from the plenum and then water flows thru the venturi at a higher velocity than the lower pressure volume of water just exiting that venturi.

dragline

  
polekaat
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Re: Fine Gold Sluice Design Help Needed ( 14:22:43 SatFeb 4 2017 )

Dragline,
I'm sorry that it's taken so long to get back to you.
I agree with Chuck on the box filling up and overflowing your system, without a lid on it. I have been trying to come up with some way to be able to introduce material into the unit, if it was sealed. The only thing I have come up with, so far, is a "feed pipe" with a couple of flapper type checks internally. When the weight of the material overcomes the water pressure, inside the unit, it should allow some material into the unit. But keeping the material moving, after it is wetted, from below, would be a hindrance.
The same issue comes to mind, for the hopper. I don't know if the water flow, passing by, the punch plate will be enough to keep the material moving, in a efficient manner. Perhaps some sort of perforated tubes, with positive pressure water flowing from them, near the bottom, of the hopper, to keep the material moving.

Trevor
[2 edits; Last edit by polekaat at 14:24:56 Sat Feb 4 2017]



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We're all victims of our own gene pool. Apparently someone pee'd in yours. "Walter Bishop"
 
 
dragline
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Re: Fine Gold Sluice Design Help Needed ( 18:18:24 SatFeb 4 2017 )

geowizard & polekaat,

I appreciate both of your guys comments, but I will have to respectfully disagree with both of you. You obviously do not see what I see. Hopefully I can correct that condition.

Let us entertain a short series of four mental experiments that you both can hopefully follow.

These mental experiments involve making adjustments to certain adjustable elements of this design as previously described. At no time during these mental experiments will I be making any changes to the design.


Mental Experiment #1.

1. Water from the 7250 GPH pump (not shown) flows thru input (A) of 12.57 sq in into plenum (B).

2. The multiple venturi jets (C) is closed to 0% effective open area relative to input (A).

3. The main venturi (D) is also closed to 0% effective open area relative to input (A).

What happens? Because plenum (B) has no outlets the pressure in plenum (B) rises to the pressure limits of this pump at approximately 49 feet of head (~21.24 PSI).

Does the hopper fill with water and overflow? No, because there is no water flowing out of plenum (B). With the exception of plenum (B) the remaining areas of the sluice, including the hopper and the sluice riffles, are dry.


Mental Experiment #2.

1. Water from the 7250 GPH pump (not shown) flows thru input (A) of 12.57 sq in into plenum (B).

2. The multiple venturi jets (C) are opened to 100% of the effective open area relative to input (A), or 12.57 sq in.

3. The main venturi (D) is closed to 0% effective open area relative to input (A).

What happens? 100% of all water from pump (not shown and precise GPH not calculated) flows thru the input (A) into plenum (B) and then proceeds to flow thru multiple venturi jets (C) into general hopper (G) regions.

Does the hopper fill with water and overflow? Perhaps likely, but the hopper filling to overflow (H) would depend upon the height (head) between water level supply to pump (not shown) and hopper opening (H), as well as the resistance to flow thru (I), (J) and (K) to tails. There are too many complex and dependent interactions to say whether an overflow condition will result but it seems very likely overflow will occur given conditions similar to those illustrated and described with this experiment.


Mental Experiment #3.

1. Water from the 7250 GPH pump (not shown) flows thru input (A) of 12.57 sq in into plenum (B).

2. The multiple venturi jets (C) is closed to 0% effective open area relative to input (A).

3. The main venturi (D) is opened to 100% of the effective open area relative to input (A), or 12.57 sq in.

What happens? 100% of all water from pump (not shown and precise GPH not calculated) flows thru the input (A) into plenum (B) and then proceeds to flow thru main venturi (D). Water flowing into the riffles area of the sluice and within a couple seconds will cause the water to rise up thru standpipe (J) until it reaches weir (K) and begin overflowing weir to tails (L).

Does the hopper fill with water and overflow? No. Water will fill the riffles area (I) but will not rise higher than the level of the main venturi (D) such that the hopper (G) will remain dry and not fill with water. To understand why this is the case you need to look no further than a stroll to your toilet and a push of the handle. After pushing that handle the water level in the bowl drops as the venturi jet below forces water up thru the s-trap to the sewer (tails). As the toilet flushes and the water in the bowl disappears you will hear air sucked down thru the s-trap on its way to the sewers. In similar manner you would also hear air being sucked down from the hopper (G) of this sluice on its way to tails (L).


Mental Experiment #4.

1. Water from the 7250 GPH pump (not shown) flows thru input (A) of 12.57 sq in into plenum (B).

2. The multiple venturi jets (C) is opened to some arbitrarily chosen effective open area relative to input (A). Let us assume 25%.

3. The main venturi (D) is opened to some arbitrarily chosen effective open area relative to input (A). Let us also assume 25%.

What happens? 100% of all water from pump (not shown and precise GPH not calculated) flows thru both the multiple venturi jets (C) and the main venturi (D). In other words, all water flowing from the pump will flow into the sluice with some percentage of that water flowing thru he multiple venturi jets (C) and the remaining portion flow thru the main venturi (D). While not accurate, let us assume that 50% flows thru multiple venturi jets (C) and the other 50% flows thru the main venturi (D).

Does the hopper fill with water and overflow? Perhaps, but whether it does or does not shouldn't matter because we have seen conditions described in Experiments #2 and #3 in which there is flow to tails, and, overflow does occur (with E#2) and does not occur (with E#3).


Conclusion: The point of these mental experiments was to describe to you conditions in which the competing forces of the hopper filling with water and being evacuated of water might be balanced so as to maintain a constant water level in the hopper, neither over flowing nor evacuating and sucking air.

Geowizard: For your reference I have a bachelors degree with major in philosophy and minor in geology from the University of California Davis. I also have two years of medical school (academic years only) from the Univ of N Texas, Ft Worth.


Bonus Mental Experiment #5 (for Geowizard).
Suppose we are reproducing Mental Experiment #1 above but with the exception that the effective open area of main venturi (D) is 0.1% (i.e. 1 part in 1000 or 0.013 sq in) that of the open area of input (A).
What happens? 100% of all water flowing from the pump (not shown) flows to tails (L). The pressure in plenum (B) will quickly rise to a level approaching 49 feet (~21.24 PSI) with some extremely small volume of water jetting out thru the main venturi into the regions of the riffles (I). Bear in mind that the effective aperture area of the main venturi (D) with this metal experiment will be roughly equivalent to the area of a 1/16 inch diameter pin hole. Eventually, water flowing thru the main venturi (D) fills the entire sluice until the water level rises to (F) in both the hopper and the standpipe and then overflows weir (K) to tails (L).

Does the hopper fill with water and overflow? No.

Is the water pressure in the plenum (B) the same as the water pressure in the rest of the sluice excepting the influence of gravity? Nope. Not a chance.
Conclusion: Your repeated assertions that the pressure of the water in the plenum will be the same as the pressures outside the plenum are patently absurd under the hydrodynamic conditions of
water flowing thru this sluice.




dragline
[1 edits; Last edit by dragline at 18:25:56 Sat Feb 4 2017]

  
dragline
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Re: Fine Gold Sluice Design Help Needed ( 01:18:14 SunFeb 5 2017 )

Geowizard,

I am also convinced that the laws of physics apply here. If fact, we both believe in those same laws.

However, we have a difference of opinion about how those physical laws apply to these designs. I can only conclude that you have a general understanding of the laws of physic but you for some reason don't have a clue how to apply them in real world engineering practices.

To each his own, I guess. :smile:

dragline
[1 edits; Last edit by dragline at 01:26:28 Sun Feb 5 2017]

  
LipCa
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Re: Fine Gold Sluice Design Help Needed ( 18:14:03 MonFeb 6 2017 )

And then we finally get to this ....

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

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

In my experience, experimentation is the only solution!!"


:devil:
[1 edits; Last edit by LipCa at 18:16:02 Mon Feb 6 2017]

  
dragline
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Re: Fine Gold Sluice Design Help Needed ( 23:24:58 MonFeb 6 2017 )

Geowizard,

I can agree with you on almost 100% of your observations, opinions and calculations. I had the exact same, or very similar, opinions, calculations and conclusions as you at one point in time. It is completely understandable that you would hold fast to your conclusions.

However, I asked myself a question and eventually after a lot of brainstorming I found several answers. While offering no weight to practicality or cost effectiveness, all of the solutions I found were 100% guaranteed to work because it is only the principles that concerned me.

Here is the question: When working on land is there a way to dig placer ore from the land and introduce it into a completely sealed sluice in a manner that excludes all air?

I am absolutely certain that you can find several creative answers to this question. However, consider that we are brainstorming here. We are not initially concerned about practical mining equipment solutions. We are only concerned about possible strategies and solutions to this problem.

Here was my first affirmative answer.

Note: Do not worry about any details not mentioned such as riffles, mats, slope, flow rates, slurry velocities, etc. No discussions or considerations of these details will have any bearing on any proof of concept. All those details can and will be addressed subsequent to finding answers to the question.

A1a: We use a water pump to pump (#1) water thru a sealed sluice at a known and adjustable flow rate.

A1b: We use a second water pump (#2) to fill a hopper to a specific and adjustable water level.

A1c: We dump placer ore into the hopper but are careful not to cause the hopper to overflow.

A1d: We use a third water pump (#3) to inject water into the hopper from the bottom so as to fluidize the ore contents of the hopper.

A1e: We use a fourth trash pump (#4) to pump the slurry (fluidized placer ore) from the hopper and inject it into the head of the sealed sluice. This trash pump has a float switch/relay that turns the pump off if the level in the hopper drops below some determined level.

A1f: An adjustment is provided for pump (#1) so as to vary the flow from 0% to 100% so as to maintain a constant total flow volume in terms of GPM. In other words, when trash pump (#4) is off the output of pump (#1) will increase so as to pick up the slack. When trash pump (#4) is on and pumping slurry the output of pump (#1) will decrease appropriately.

The fact that this is a complex answer involving 4 different pumps doesn't matter. It answers the question which is all that we needed to accomplish in providing one possible answer with our brainstorming exercise.

Can you think of some other simpler solution to this problem that also answers this question?

Thanks,

dragline

  
dragline
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Re: Fine Gold Sluice Design Help Needed ( 02:44:57 TueFeb 7 2017 )

Geowizard,

So, given a sufficient number of water and trash pumps we can introduce dry placer ore from land into and thru a sluice also located on the land and the entire time this operation proceeds while no air is in contact with the slurry as it passes thru the sluice until the slurry exits to tails.

We have a mutual understanding about this, correct?

dragline

  
dragline
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Re: Fine Gold Sluice Design Help Needed ( 06:11:25 TueFeb 7 2017 )

Geowizard,

Please accept that I respect you and your academic and work related accomplishments.

However, I apologize that I will be unable to continue this conversation with you unless you are willing to communicate with me in a manner that allows me to explain and defend my ideas and designs.

With all of your dozens of replies to this thread you have not asked me one single question in an attempt to better understand my ideas and designs. Further, since you have openly stated that my designs will not work or do not have merit you have publicly besmirched me and my reputation as a design engineer and assuming you are an honorable man I believe you will do the honorable thing and permit me the opportunity to convince you otherwise. No amount a lecturing from you, or me, seems likely to convince the other as to the merits of the other's views in this matter.

Therefore, I respectfully request that you allow me to engage you in a logical discourse and argument in an attempt to convince you of the merits of my designs. If I am unable to convince you then you are welcome to engage me in an argument if you choose to convince me otherwise.

The rules of my proposed discussion will involve the tried an true methods of the Socratic method. If you are unfamiliar with this form of discourse and argumentation please take the time to read and familiarize yourself with Socrates, a Greek Philosopher from the later part of the 5th century BC.
http://en.wikipedia.org/wiki/Socratic_method

I give you this choice but you are under no obligations to accept my offer. If you choose to accept I will ask you a series of questions that you are obligated to answer, truthfully. Usually a yes or no answer will be sufficient assuming the one asking the question has framed that question properly.

If you choose not to engage me in this formal argument I respectfully ask that you do one of two things.
1. You acknowledge that my designs have merit and you engage a constructive dialog and effort to identify elements and aspects of this design that may or may not need alterations or improvements.
2. You leave this thread and do not post a response here again.

By engaging me in this argument you will be offering me the benefit of your understanding and wisdom and you will be giving me the opportunity to see and recognize the errors of my ways.

By leaving this thread and not posting further replies you will allow me to engage and accept constructive comments and criticisms from the other members of this forum.

The choice is yours.

Thank you,

dragline

  
polekaat
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Re: Fine Gold Sluice Design Help Needed ( 14:11:56 SatFeb 11 2017 )

Dragline,

It's been awful quiet on here for the last few days. Looks like the argument has ended.
In the time that this thread has been active, you could have a working prototype built and be testing it. There were a few, constructive suggestions, made to modify your original design. I say, take it and run with it. The best way to prove your design is to show it in action.

Good luck,
Trevor



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We're all victims of our own gene pool. Apparently someone pee'd in yours. "Walter Bishop"
 
 
dragline
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Re: Fine Gold Sluice Design Help Needed ( 04:44:13 SunFeb 12 2017 )

polekaat,

Yes, I am currently moving forward with my prototype designs. For my first prototype build I will be running with a simpler and scaled back version of the subsurface sluice previously posted in this thread. In other words, I have not presented illustrations of my first subsurface sluice prototype but I'll eventually get around to illustrating those designs and posting those here for your reference. Despite not having any illustrations for my first subsurface sluice prototype to discuss, I would like to move our discussions forward to subsurface sluice prototype field testing.

Today I acquired the flotation foundations for the dredge in which my prototype sluice will be installed, a used 12 foot SD365 Saturn Inflatable Boat and Trailer:


Click to enlarge.

I haven't yet acquired much of anything else for this project, but next up on my acquisition list will be a used 10 to 20 HP 4-Stroke outboard motor. The trailer that was included with the boat is lightweight and not a bad if not older trailer. But it is a flatbed that was not ideally outfitted for this boat. So, I'll shortly be constructing a superstructure for this flatbed that will hopefully be more appropriate for this boat.

This specific Inflatable Boat is rated for up to 5 passengers, up to a 30 HP outboard motor and a maximum load capacity of 1,213 lbs, so I anticipate that it will be adequate for my first reduced-scale prototype build. One thing I could use help with from the forum members here is determining the specifications for purchasing a cheap trash pump that will service as the medium/high pressure water source for this dredge. Bear in mind that I'm not looking for a Honda engine at this time seeing that I can and probably will upgrade my prototype dredge to a Honda once prototype designs have proven valid thru field testing.

My initial designs and calculations suggest that a typical high pressure dredge water pump might not be optimal for my dredge. The pump pressures (head) required from my dredge will be less than most dredges such that increased flow volume will be favored. I anticipate my dredge will function adequately with a maximum head (pressure) of between 100 and 140 feet. The pump's flow volume at zero head desired would be a minimum of 15,000 GPM up to about 25,000 GPM. After I decide upon and acquire a trash pump I can then optimize the designs for my prototype sluice specific to that pump.

Here are some design criteria for my dredge.

1. The inflatable boat you see above will serve as the foundations for the dredge.

2. This inflatable boat will independently be powered by an approximately 10 HP 4-Stroke outboard motor that will serve to motor the boat over water some distance to the prospector's desired dredging position.

3. At this time, the only type of dredging location and environment where dredging operations will be performed are Oregon coastal river estuaries. The reason for this location stipulation is because the State of Oregon has placed a moratorium on and prohibiting almost all powered dredging with the exception that in some or most situations coastal river estuaries have been excluded from this moratorium.

4. The dredge will be powered by a 7 to 9 HP 4-Stroke gasoline engine driven trash pump.

5. The human dredge operator will remain in the boat at all times during dredging.

6. The design elements of the dredge will need to be discussed in greater detail in subsequent replies, but suffice it to say that the dredge I am intending to design and build will be generally similar to what was discussed in a previous thread entitled: "Hydraulic Well Drilling to Bedrock for Gold!"

7. The types of alluvial placers that will be targeted with this dredge are sand and gravel bars devoid of larger gravels, cobbles or boulders. So, basically, I'll be dredging large estuary placer deposits of low value gold bearing sands, coarse sands and/or smaller gravels.

8. The characteristics of the targeted gold will be very fine gold averaging between 100 and 150 mesh particle size.

9. The suction dredge intake diameter will be approximately 4 inches in diameter or slightly less.

That's it for now. I'll get to work on designing some hydraulic well-drilling dredging heads so you can hopefully get a feel for what type of trash pump might be both cheap and functional.

dragline

  
dragline
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Re: Fine Gold Sluice Design Help Needed ( 19:08:33 SunFeb 12 2017 )

So, this morning I bought a cheap 7 HP gasoline pump for my first attempt at a field testing phase for this project. It is not anything special (given that it's not a Honda) but it was really cheap at $185 (with free shipping) for a 208cc gasoline engine trash pump. I'm not expecting it to work forever so feel free to ridicule me when this thing breaks down after only a few dozen hours. I'll be happy and consider myself lucky if I can get a couple hundred hours from this thing.


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")

Specifications:
16,000 GPH at zero head
26 ft max suction lift
95 ft max head
1/2" max soft solid size
1/4" max hard solid size
7 HP OHV 208cc 4-Stroke
Fuel tank capacity: 3.8 Qt
Noise level: 64 dB
Includes a few Misc. fittings

I have been trying to figure out a way to save $1,000 to $1,500 by not buying a 10 HP outboard motor for my boat. This might be possible if I were to be able to decouple the output from this pump and couple that to a steerable water jet at the back of the boat. I'd then have a 7 HP jet boat and not need the outboard motor. The problem is that I couldn't justify attempting to do that with this pump seeing that it wouldn't be reliable enough and I wouldn't want to get stuck a long ways from put-in with nothing but those flimsy ores.

dragline

  
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Re: Fine Gold Sluice Design Help Needed ( 01:19:14 MonFeb 13 2017 )

You wouldn't have a seven hp motor with the trash pump Dragline. Jets on boats us high pressure/low volume jet pumps. Even that that you lose over 1/3 thrust using a jet than a prop.

Not sure what you are going for, but wonder if the trash pump will work on a venturi system because a venturi depends on high pressure to create suction.

Your trash pump is set up for volume, not high pressure. Not trying to discourage you, and maybe not understanding the concept, just wondering if you thought of this.



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dragline
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Re: Fine Gold Sluice Design Help Needed ( 04:59:03 MonFeb 13 2017 )

Jim,

Yes, your observations concerning my thoughts about the use of this trash pump for turning my inflatable into a jet boat are entirely correct. I assure you that it would work, sort of, but not in any way efficiently. I agree that it would probably be a miserable performing jet boat but certainly better than the flimsy ores that came with the boat. I'll definitely be acquiring a 10 to 20 HP 4-Stroke outboard prop motor for pushing this boat around.

But when it comes to the hydraulic well drilling sand gold dredge concept designs I have going here, I assure you that this pump is a lot more ideal than your typical gold dredge pump. Typical gold dredges do use very high pressure at low flow volume pumps. But as you probably already guessed that's not what I'm up to here.

The concept I am working with here wont' function or behave like your usual gold dredge. Instead, I'm designing something more similar to a hydraulic well drilling rig. Imagine, if you will, cramming a typical gold dredge nozzle into a sand bar as hard as you can. What would happen? You'd probably stall the intake such that the entire flow volume up the suction hose would be equivalent to the jet flow volume because you buried and jammed the nozzle opening into the compacted sand and there would be no surrounding water flowing into the suction intake.

I hope that you can understand my point here. If you look at hydraulic well drilling rigs you'll notice that all of the water flowing out of the hole will be supplied by the pump that is pumping water down to the bottom of the hole where a hydraulic jet cuts (erodes) the soil which then flows up the hole to the surface. Now imagine that your hydraulic well drilling doesn't just have a single pipe with water flowing down but there is another suction pipe coaxial, concentric adjacent or mated to that medium/high pressure water supply.

I'd like you to refer to the illustrations below. The 2 inch diameter Schedule 40 PVC pipe supplies water under pressure in a downward direction that acts as a hydraulic jet to erode material, presumably sand or small gravel, as the drill is pushed into the sand. The 4 inch diameter Schedule 40 PVC has a water jet at pressure helping to push the contents into the sluice. Granted, neither the downward aimed hydraulic excavation jet nor the upward aimed elevator jet are under the very high pressures common to our typical of your usual gold dredge. But then again they don't need to be nor should these be flowing at such high pressures for this rig to operate most efficiently.

The following illustrations represent cross sections of two different approaches to a hydraulic well drilling system each using two Schedule 40 PVC pipes, a 2 inch diameter supply and a 4 inch suction elevator.

Concentric (coaxial) Supply and Elevator:


Non-Concentric (coaxial) Supply and Elevator:


The difference between these two approaches is that the non-concentric design achieve an equivalent of an additional 5/8" diameter for the upward suction pipe. This might not sound like a lot but it really is a big deal when the non-concentric configuration increases the upward flow area by 40% which would likely result in an overall increase in production capacity of almost 75%.

I realize that very little about these designs should make a whole lot of sense to the members here seeing that very few if any of these design concepts as I am employing here are in common use with your typical gold dredging operations.

Perhaps my use of a trash pump capable of 16,000 GPH (at zero) head or 96 feet of lifting head (42 PSI) doesn't immediately seem to make sense. Understand that absolutely all of the water that lifts the placer sands and gravels coming up from the bottom of the bore hole must be supplied from the pump. This is a very different situation than your typical high pressure jet driven gold dredge nozzle.

Hopefully this is making sense, but if not, let me know if you have questions or comments.

dragline
[2 edits; Last edit by dragline at 05:06:06 Mon Feb 13 2017]

  
shaftsinkerawc
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Re: Fine Gold Sluice Design Help Needed ( 18:34:48 MonFeb 13 2017 )

Keep working your ideas Dragline!
Just a couple of thoughts.

I think you meant GPH on these figures earlier, "would be a minimum of 15,000 GPM up to about 25,000 GPM"

Most drilling requires turning of the drill stem to help prevent binding and pinching which you non concentric wouldn't allow.

Also your input water has to be balanced to what your pulling out of the hole so you don't get the quicksand effect around your drill stem. Too little up the pipe and you push the extra water into surroundings at depth, to little and you draw extra in from depth which may collapse your hole.

In the other post you questioned having an elutriation tower and without proper flow any vertical rise of solids and fluids will create one.

Testing will tell! How deep can you get without hitting larger rocks?

  
dragline
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Re: Fine Gold Sluice Design Help Needed ( 22:35:19 MonFeb 13 2017 )

shaftsinkerawc,

Your comments:

C1. I think you meant GPH on these figures earlier, "would be a minimum of 15,000 GPM up to about 25,000 GPM"
Response: Yes, exactly... my misuse of Minute vs Hour there... sorry. That said, I can realistically work with almost any capacity pump seeing that I haven't designed or build the subsurface sluice yet. The pump I bought is rated at 16,000 GPH (267 GPM) at zero head and I anticipate netting about 8,000 to 10,000 GPH (~150 GPM) at full throttle in practical use.

C2. Most drilling requires turning of the drill stem to help prevent binding and pinching which you non concentric wouldn't allow.
Response: Right, well, that's not how it is going to work in practice. I've played around in these beach sands a lot and I am familiar with their physical characteristics. While I haven't built this drill head yet I am leaning towards the off centered for several reasons and the fact that the supply and suction pipes are off-center is actually going to help establish and maintain a region of loose sand and slurry surrounding the bore hole as I rotate the drill head assembly left and right. You might go back and read my thread on my Beach Auger efforts to see what I am getting at here in regards to the liquefaction propagation effect radiating out from the bore hole once the sands are loosened. Suffice it to say that the off-center piping design will not get stuck nor will I have any difficulty rotating these pipes owing to the liquefaction of surrounding sands.

C3: Also your input water has to be balanced to what your pulling out of the hole so you don't get the quicksand effect around your drill stem. Too little up the pipe and you push the extra water into surroundings at depth, to little and you draw extra in from depth which may collapse your hole.
Response: You make some reasonable inferences here, however, the quicksand effect is exactly what I expect and want to happen. If you haven't deeply dredged beach sands below the water table you probably have not seen this quicksand (liquefaction) effect in its full and completely ridiculous glory. Bear in mind that I will be sitting in a boat that is floating above the beach or estuary sands and I'll be in no danger of falling into the quicksand abyss below me. I'll have a 6 or 8 foot length of Schedule 40 PVC pipe or pipes with an assembly of mated 10 or 15 foot lengths of 2 inch and 4 inch suction hose connected from those drill head pipes to the pump and the sluice.

C4: In the other post you questioned having an elutriation tower and without proper flow any vertical rise of solids and fluids will create one.
Response: Right, well yes, but only trivially and temporarily. If the flow velocity in the upwards direction is faster than the settling velocity of the densest and heaviest materials then those elutriation effects are meaningless as all materials are quickly transported upwards and to tails. Regardless, there will be no or very little upwards flow in my sluice with this current project so you can safely ignore those effects and subsequent concerns. The only majorly upwards flow for this dredge occurs in the well head suction pipe and hose and I hope you would not be tempted to call those elutriation towers?

C5: Testing will tell! How deep can you get without hitting larger rocks?
Response: There really won't be any larger rocks larger than sand unless and until I am able to drill deep enough to reach such a stratum and that could occur at 1 foot or 100 feet deep based upon my beach digging experiences (the deepest I've dug into the beach was about 15 feet with my beach sand auger). But my intention is to design, build and place a cone made of screen or punch plate with a 40% open area of 1/4 holes or the equivalent heavy duty wire mesh. Assuming I can find the wire mesh I'll probably find that easier to roll into a cone than the punch plate.

My comments: It seems as though you and perhaps other forum members are getting close to an understanding of what this thing is and how it will work. Without the aid of illustrations to give you a picture of what I'll be doing allow me to verbally describe how this will work.

1. I will use 3 anchors to securely position the boat in 1 foot to 4 foot deep water with a sand bar or ocean bed underneath.

2. I will then drop the drill head pipes thru a small hole in the bottom of the inflatable boat until the cutting head reaches the sand.

3. I will then prime and turn on the pump and make sure that all pump and sluice conditions are operational within acceptable allowances.

4. I will rotate the drill head pipes left and right as I push the cutting head and pipes down into the liquefied sands as deeply as I am able, i.e. I will continue drilling down until the head either hits a stratum of rocks, or cobbles, or bedrock, or I will push the head downward to the maximum depth I can considering the available lengths of suction hoses between the pipes and the pump and dredge.

5. Once at maximal depth I will secure drill head pipe or hose to the boat and then allow the hydraulic dredge to operate hands free for some number of minutes or hours until the output of the slurry entering the dredge begins to clear.

6. It is my contention that a properly designed hydraulic cutting head at depth will hollow out a large cavity in the sand bar or sea bed which when sufficiently large will cause the sands surrounding and above that cavity to collapse inward or down under the force and agitation of the hydraulic cutting jets. The sands once liquefied will be quickly suctioned up the dredge nozzle and then be delivered thru the sluice to tails.

7. Assuming this dredge works hands free as intended, and assuming I can get the cutting head 10 or even 20 feet in depth it would not be unreasonable to conclude that the hands free dredging process could proceed for up to 3 or 4 hours with a total production processing of 5 to 10, or more, cubic yards of sand per hour. Assuming that a depth of between 15 to 20 feet were attained the limiting factor concerning total cubic yards dredged and processed would be regulated by the State of Oregon's mandated limit of 30 cubic yards processed per day for recreational dredging.

8. Assuming this dredge works hands free I'll probably need to take along my fishing license, rod and bait while I fish for a few hours as I wait for the dredge to complete its work.

dragline
[8 edits; Last edit by dragline at 15:45:31 Tue Feb 14 2017]

  
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Re: Fine Gold Sluice Design Help Needed ( 03:36:06 WedFeb 15 2017 )

dragline,

I am attaching a link to oceanic tide predictions for the southern Oregon coast for your reference.

https://tidesandcurrents.noaa.gov/noaatidepredictions/NOAATidesFacade.jsp?Stationid=9432373

Aside from waves and swells which you have probably already worked out a solution, the tidal change of about 7 feet over 12 hours would need consideration.

What is the plan for the drill with a seven foot tide?

The water craft is as you said, anchored. Swells and wave action are random and add to and subtract from the predicted tidal movement. Tidal pools form at low tide and may be quiet for a short period. As the tide moves in and the water level rises, the anchor lines will have to be extended. With small two foot waves, the wave action will move the boat up and down. Add swells and then subtract the swells, you can go from beach to 10 feet of water.

Is this a problem? :confused:

- Geowizard

  
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Re: Fine Gold Sluice Design Help Needed ( 06:57:38 WedFeb 15 2017 )

Geowizard,

Yes, tides can definitely be a problem sometimes, but definitely not all times. I do quite a bit of beach mining and the tides definitely factor into whether I'll be heading to the beaches for the weekend or finding something else to do. When the weekend's tides are wrong, there is no point attempting to mine some beaches. Other beaches, on the other hand, are much more forgiving because there can be lot's of room above high tide for mining.

Interestingly, Oregon State regulations permit power equipment above the grass line. The problem with that is that there is no water above the grass line! State regulations also say that to use power equipment you'll need to be at least 300 feet from any waterway (stream, river, wetland, whatever). You can probably see how this is somewhat of a Catch-22. You can use power equipment above the grass line but not within 300 feet of water so, by definition, you'll have no water!

There are workarounds for this problem. One solution that always works is to bring your water with you such as a 55 gallon drum of water or a smaller tub of water to use for a re-circulatory system. All such strategies of bringing your own water severely limit one's productivity.

Another interesting workaround that I've only partially been successful with is, once you are positioned above the grass line, auguring a borehole to and a below the water table and digging yourself a well to supply the water you need to run your dredge! While this might seem like a workable strategy I've not quite figured out how to strain the water thru the sand below the water table. The next time I attempt this I'm going to try wrapping some fine polymer window screen around the strainer and see if I can pump water while leaving the sand undisturbed. Not surprisingly, there's plenty of water available everywhere on or above the beach if you dig (a well) for it and have the right equipment to pump that water to your dredge, sluice or whatever.

But you'll notice that while I did reference the potential for dredging low value ocean sands, I always tried to conjoin a reference for estuary sand bars. The physical characteristics of ocean sands and estuary sands are very similar as you might have guessed. Both can contain small amounts of gold but more importantly, some estuaries have zero tides. How can this be possible?

Interestingly, one such zero tide estuary at the present time is the Sixes River. While this isn't the case every year it has been the case most years for the last 20 or so years. What happens with the Sixes River estuary is that there is a large beach berm that forms at the mouth or river terminus such that it is higher than high tide. This forms a temporary dam that forms an estuary lake of sorts with the river flowing over the beach berm.

Anyways, there are plenty of river estuaries, indeed most Oregon estuaries, where one can locate a powered dredge above the reach of high tide and yet below the regions of the river designated as essential salmon habitat, which by definition the State of Oregon uses for their moratorium (ban) against power suction dredges.

When attempting to dredge ocean placers, another approach might be to use the neap tides to one's advantage. A neap tide occurs just after the first or third quarters of the moon when there is the least difference between high and low water. Theoretically, once might be able to use my inflatable boat strategy to dredge for a period of time of 1.5 to 2.0 hours before and after either the high or low tides when the tidal effects upon a small boat would be minimized.

But again, I'm not entertaining the idea of jumping into the ocean with this project anytime soon. Initially I'll be finding locations in various river estuaries where sand bars are present and the tidal effects are minimized. Assuming that I can get the bugs worked out and get this project working well with estuary sand bars I'll, perhaps, consider hitting the surf for 2 to 3 hours spanning the high or low tides.

Take a look at the tidal chart again and you'll see what I'm referring to here regarding neap tides and/or the tides surrounding the high or low tides. Suppose I were to put my inflatable boat out from a shallow sloping beach where and when the surf was minimal. I choose the date of 02/16/2017 and start dredging at 8:00 AM and stay out dredging for 4 hours until 12:00 PM. What are the tides?
8:00 AM: 3.00 Feet
10:00 AM: 1.75 Feet
12:00 PM: 3:00 Feet

Can you see what I'm getting at here? I dredged the ocean floor for 4 hours and the total tidal variation during those four hours was 1.25 feet or 15 inches.

As any beach miner over the last several hundred years would tell you, planning for a successful day is all about timing.

dragline

  
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Re: Fine Gold Sluice Design Help Needed ( 17:43:57 WedFeb 15 2017 )

dragline,

I am providing a link to the definition of "elutriation" for reference in order to reduce confusion on what elutriation is.

https://goldbook.iupac.org/E02053.html

  
dragline
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Re: Fine Gold Sluice Design Help Needed ( 18:29:40 WedFeb 15 2017 )

Geowizard,

Regarding the definition of the word "elutriation" that was my understanding also but I'm not sure why, where or what caused this supposed confusion. Hopefully this concern relating to and the use of this word will fade as design elements and functions of this project become more clear.

dragline

  
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Re: Fine Gold Sluice Design Help Needed ( 00:42:54 ThuFeb 16 2017 )

dragline,

The vertical column (drill?) illustrated above is by definition, an elutriation column.

There is a wealth of information on attempts to use an elutriation column for recovery of gold. The information relates attempts made over the past 100 years to separate gold with an elutriation column.

I understand you are merely attempting to pump slurry from the bottom of your hole. The principle involved is a problem for gold and other heavies. The settling velocity of gold is one consideration but the show stopper is the drag along the sides of the suction tube. The drag REDUCES the UPWARD velocity to less than the settling velocity and the result is that the heavies fall back down to the bottom of the hole.

Drag along the edges slows the flow on the edges. The slow flow isn't able to suspend the gold. The gold falls to the bottom of the column.

Elutriation is successful in keeping the gold on the bottom of the column.

- Geowizard
[2 edits; Last edit by geowizard at 01:42:19 Thu Feb 16 2017]

  
dragline
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Re: Fine Gold Sluice Design Help Needed ( 03:59:54 ThuFeb 16 2017 )

Geowizard,

I will read the definition of the word "elutriation". Here it is...

"The process of separating the lighter particles of a powder from the heavier ones by means of an upward directed stream of fluid (gas or liquid)"

One should ask the question for any given situation: "Does separation of lighter and heavier particles occur in an upward directed stream?"

If separation does occur, i.e. the heavies go down and stay down and the lights go up and stay up, then yes, an elutriation column might be an accurate description of the situation.

But what about the gold suction dredger who is sucking up placer ore and gold from the bottom of a river or the ocean. If everything, both heavies and lights, that enters the nozzle is delivered to the sluice at the surface, does the dredger's suction hose fit the definition of an elutriation column?

If you're saying that drag along the edges of a dredger's vertically positioned suction hose would prevent any gold sucked up that hose from reaching the sluice, I am sure there are a lot of gold dredgers that might disagree with you about that.

dragline
[1 edits; Last edit by dragline at 04:00:38 Thu Feb 16 2017]

  
geowizard
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Re: Fine Gold Sluice Design Help Needed ( 04:03:10 ThuFeb 16 2017 )

dragline,

Back in 2011, I picked up a new Mini-6 inch dredge at Keene.

http://www.keeneeng.com/mm5/merchant.mvc?Screen=PROD&Product_Code=6218HM

It used twin GX270 Honda engines. Using the full length of hose almost assured a blockage. The suction hose would load up with sediment. So, I cut off about half of the suction hose. That improved the operation.

My concern is related to the performance of a suction drilling operation with much less power and attempting to lift sand vertically with gold. I would never have attempted to suction dredge a hole 10 to 20 feet down. The reason is because the pumps - running both at max 18 HP would have minimal or not any probability of doing the job. The thought never even came to mind because I could see the performance was approaching the point of trade-off between power available and the power needed.

Operating a dredge with minimum lift is a challenge. Minimum lift provides maximum flow. The more lift that is required, with limited power, the lower the flow that can be obtained.

In the hydro-drilling operation, looking purely at the relative power needed to obtain the flow (realistically) would dictate a 20 HP to 40 HP Diesel pump.

Success in this type of endeavor is usually attained in a design that has an overabundance of power. Cutting costs and putting a minimal system in place increases the chance that the power available will be less than the power demanded by the design.

Much of the regulatory process that is put in place to control dredging is by design! The regulatory bodies have engineers that look at what is possible within certain power constrains and regulate the permitted equipment at a power level that is less than the power needed to do the job.

That's why "recreational" dredging has a six inch limit. You actually cannot mine at a profit with a six inch dredge. The power required and the suction hose size needed to mine the required amount of cubic yards to mine on a commercial basis starts at 8 inches and goes up from there.

You don't see dredges offshore at Nome running 7 HP trash pumps with a 4 inch suction hose!

So, the hydro-drill falls in the realm of "recreational". Recreational mining is a fun experience and has no profit motive. Wasting one's time and wasting one's spendable income on "fun" provides value in whatever the goal IS as recreation goes.

So, if the design isn't serious, I understand. The design doesn't have to be functional or make sense in the world of what we know and understand about dredging.

What we know and understand about drilling;

Conventional drilling as mentioned above by others requires "rotation" of the drill stem. Your drill stem will oscillate clockwise and counter clockwise within a certain number of degrees and presumably propel on it's own down to bedrock.

How do you add sections of drill? :confused:

Conventional drill stems are "made up" by adding sections of drill pipe. Sections are screwed together to lengthen the frill stem. Sections are removed "coming out of the hole".

You cannot screw sections onto your drill stem.

Plastic drill sections reach their limit quickly. The limit is imposed by the torque required to twist the drill pipe. The plastic drill pipe will "twist-off".

Keeping a design within the realm of what has been proven to work - i.e. drill pipe made of steel improves the probability of success. Going outside of the box and using materials that are not capable of handling the torque and stresses imposed in normal drilling spells a recipe for failure.

- Geowizard

  
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Re: Fine Gold Sluice Design Help Needed ( 05:09:03 ThuFeb 16 2017 )

Geowizard,

You make some excellent observations and I have to agree with just about every comment you make, especially regarding State regulations by design being written so as to prevent profitable mining recreational operations.

My estimates for the production capacity of this hydraulic dredging system using a 7 HP pump may indeed be overly optimistic and unrealistic. When I mention that my goal is to hydraulically drill to and reach a depth of 15 or 20 feet I mention this depth not as a claim specific to a 4 inch suction pipe and a 7 HP pump.

Please consider these specifications regarding depth in relation to solids percentages as conceptual. Your estimates such that the power needed to elevate a 50% solids slurry from the depth of 20 feet may indeed require a 20 HP engine for a 4 inch suction nozzle opening.

But what if instead of a 4 inch suction pipe and nozzle opening I employed a 3 inch, or even a 2 inch. Would a 7 HP engine be sufficient in such a situation? Or, suppose instead of lifting 50% solids slurry from 20 feet I only needed to lift it from 6 or 8 feet. Might then a 7 HP pump be sufficient? Perhaps. But I won't know what depth is practical and productive with any given pump and pipe/nozzle size until I try.

Oregon State regulations limit the suction nozzle opening to 4 inches. Those same regulations also limit the power of the pump to 15 HP and the volume of material processed in a day to 30 cubic yards. You couldn't be more correct about these regulations designed to impose and render small scale placer mining operations unprofitable.

You asked the question: How do you add sections of drill?

Answer: I figured out a long time ago that adding sections to the drill column will not be practical at this early developmental stage of this design project and therefore I'll need to design this system so as to have a fixed length. I will be starting out with a 12 foot inflatable boat that can practically stow drilling pipe segments up to about 6 feet long or slightly longer.

My best working concept at the present time involves 4 or 5 foot sections of PVC pipe connected via flexible suction hose that will allow each pipe section to be folded 180 for compact stowing. In other words. Let us assume I'll be going with about three 4 foot PVC pipe sections each connected together with 18 inches of suction hose overlapping 3 inches on the pipe ends such that I will net 12 inches suction hose between pipe ends. What will be the total depth obtainable?

3(x) 4 ft Sch 40 PVC Pipe = 12 feet
2(x) 1 ft Suction Hose = 2 feet
1(x) 6 ft Suction Hose = 6 feet
Total length of all segments = 20 feet
Practical drilling depth = 12 to 15 feet

If in practice I can only lift 50% slurry from a depth of 8 or 10 feet with this 4 inch system then I might probably consider designing a constructing 3 inch system and see how deep that will go with my 7 HP pump.

If it becomes apparent that the 7 HP pump isn't cutting the mustard then I can upgrade to an inexpensive 9 HP or 13 HP pump.

Perhaps it will help the general understanding if I were to generate an illustration for my current drilling pipe sections and connections. But you are probably going to raise concerns about the use of Sch 40 PVC pipe connected with suction hose and the ability for that pipe, hose and connections to withstand the torsional forces that would be incurred when twisting left and right during the drilling process. However, I predict that these torsional forces will be minimal owing to the fact that beach, ocean or estuary sands are not characteristically typical of common soils or alluvial sediments that you would encounter when drilling a well on land.

I anticipate that the hydraulic jet or jets at the bottom of the drilling pipe will not have trouble rapidly liquefying these sands well before the nozzle cutting pipe makes hard contact and therefore very little rotation with cutting action at the nozzle will be necessary. Of course I only have my experience and practice working beach sand sediments to base my assumptions and it is possible that ocean or estuary sand sediments may be characteristically different and more challenging to excavate.

So far none of your criticisms or concerns have caused or inspired me to materially alter or make improvements to my designs. However, I anticipate this condition will likely change as it appears to me that you are beginning to understand the general principles and practices of my designs and make relevant observations and raise appropriate concerns.

dragline

  
dragline
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Re: Fine Gold Sluice Design Help Needed ( 05:39:35 ThuFeb 16 2017 )

Presently I am inclined to favor an off-center configuration of the suction versus hydraulic pipes (see previous illustrations above) although I am not completely certain this will be most practical. I have a different concentric configuration illustration below that involves a 6 inch diameter coaxial hydraulic pipe.

These specific PVC pipes are very thin and likely wouldn't hold up in practical use but they are cheap and might be sufficient for limited testing use only. Schedule 40 PVC pipe is a lot more costly but would definitely be better suited for actual productive use.

I submit this design for reference (only) seeing that I don't consider this configuration to be all that probable or practical. It is just a concept that I believe deserves a mention owing to the fact that it helps solve certain concerns encountered with an off-center configuration.



Be aware that I still have many practical and mechanical concerns about my current designs that I have not mentioned, and that no forum members have commented upon as yet. Hopefully I'll be able to resolve those problems before too many more critical reviews or discussions ensue from the forum members.

dragline

  
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Re: Fine Gold Sluice Design Help Needed ( 14:07:23 ThuFeb 16 2017 )

dragline,

Several comments that I would like to make;

I take personal interest in your ideas. My advice is given freely as a matter of conversation. I would give my brother the same advice if we were discussing the same situations you are presenting here on the forum.

Why don't the other two thousand members chime in? :confused:

I call it the "Forum Phenomenon". A high percentage of members are passive viewers that are generally interested in Gold Prospecting. The majority of members like to read discussion on topics like this one. If we were having this discussion on the street, there would be a group of listeners that might stop and "listen" to the discussion. So it is, here on the Alaska Gold Forum. Without knowing for sure, there are probably thousands of non-members that drop by to look at on-going discussion. Jim probably has statistics on "page views".

When I returned to Alaska in 1975 - after getting out of the Air Force, I worked on Oil Well Drilling Platforms on Cook Inlet. That experience led eventually to training Field Engineers on Oil Well Drilling and Completion in Houston.

Suffice it to say, I have direct - hands-on experience working on and around drilling rigs.

Drilling a hole in the ground is not a trivial task. Drilling a hole in unconsolidated wet sand is not trivial. The process has known challenges that require solutions. The solutions are well known to those skilled in the art of drilling.

You need a DRILLING RIG. In your application, your drilling rig requires a "drilling platform". The drilling operation is only as stable and reliable as the drilling platform. A drilling platform is made of steel. It's expensive because steel is expensive. Offshore drilling platforms must be "spudded" into bedrock. The legs are the support system. The drilling platform is placed at an elevation that is higher than the maximum tide + all possible swells + all possible waves. It isn't trivial.

A Drilling Rig must have a means of lifting drill pipe and supporting a drive. That involves having a "derrick". It involves having a winch - also known as "draw works". The draw works include shieve wheels (pulleys) and appropriate steel cable to perform the task of lifting the drill stem under all possible load conditions. Drilling rigs have either a "top drive" or "bottom drive" to rotate the drill stem. Mud is pumped with a specially designed positive displacement mud pump. The mud pump has to be specified according to the expected pressure and flow requirements of the drilling operation. It can run from hundreds of psi to thousands of psi. The mud provides lubrication and a transport for drill cuttings - even sand. If the mud pump stops - the drilling stops and you may well be looking at a "stuck drill". It isn't trivial.

Even a small scale offshore or lagoon drilling platform must include all of the above at a minimum.

- Geowizard

  
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Re: Fine Gold Sluice Design Help Needed ( 15:40:37 ThuFeb 16 2017 )

Lost circulation;

One of the many concerns that are addressed by drillers is "Lost Circulation".

Lost circulation can be catastrophic for a drilling campaign. It can lead to a stuck drill stem AND loss of the well.

That brings us to the issues related to lost circulation. The reason for lost circulation is loss of control of the drilling mud. The mud is pumped under high pressure - down the hole. The mud may find a direction of travel that was not the intended direction!

To control the drilling mud, drillers use surface casing in unconsolidated ground. Mud will move out and away from the drill hole when it is free to escape into the surrounding ground.

Mud engineers;

Yes, there is a science that surrounds MUD. Mud provides lubrication of the drill stem as well as a vehicle to transport cuttings from the drill hole. Mud has a third important role in providing "support" for the borehole wall. In deep wells, the mud is "weighted" to provide a fourth role of maintaining positive hydrostatic force in the well. It's a science and it requires attention to all of the qualities afforded by having the proper drilling MUD. :smile:

- Geowizard
[1 edits; Last edit by geowizard at 15:42:26 Thu Feb 16 2017]

  
geowizard
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Re: Fine Gold Sluice Design Help Needed ( 15:57:33 ThuFeb 16 2017 )


Drilling mud continued;

When drilling mud is used in well drilling, the mud is circulated. Mud is expensive because additives are expensive. Mud is expensive in terms of the cost expended in maintaining the exact chemistry of the mud.

Handling mud is not trivial.

A mud pit is part of the plan. The mud pit provides a reserve storage area for the mud. The mud is pumped from the mud pit through a shaker screen to remove solids. Additives are placed into the mud to improve the quality of the mud for every specific drilling operation. The requirements are different in every different drilling project. The screened and conditioned mud is circulated into the well. The mud may flow down the annulus between the drill stem and up through the drill stem or it may flow down the drill stem and up the annulus.

One other purpose of drilling mud is lubrication of the drill bit. Drill bits cut better and last longer when they are lubricated. Drill bits are high cost items to replace.

- Geowizard

  
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Re: Fine Gold Sluice Design Help Needed ( 17:02:43 ThuFeb 16 2017 )


Mud logging;

What is a "Mud Log"? :confused:

In the process of drilling wells, there is often a need to create a record of the rock formations. The record is referred to as a "Log". A geologist is usually employed to take samples of the drilling mud on a regular basis. The samples are documented in the log to provide a record of the rock types at different depth as well as the content of the rock in terms of mineralization - in mineral or precious metals prospecting.

Beach prospecting;

Mud logging can be done as a drill bores a hole down through layers of sand. All of the forces of wind and sea has been at work sorting and shifting the sand. There is a sequence of layers in the sand that may have more or less gold at specific depths. A record of the amount of gold - obtained simply by panning the sand at regular intervals could reveal a layer of pay.

When logs are compared from one hole to another, it's possible to form a map of the amount of pay in each hole with correlation to depth of pay and thickness of pay.

All of this is important if and only if the endeavor has a commercial objective.

- Geowizard

  
Fleng
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Re: Fine Gold Sluice Design Help Needed ( 17:31:25 ThuFeb 16 2017 )

Not sure if drilling mud is actually needed for dragline's system. If a high velocity pump is forming a slurry at the head and a suction system is pulling out sand as he has stated- no cutting head is necessary. We are talking about beach sand not a rock formation.

His system is modified "hydraulicing". The YouTube video a few months back showed a guy simply siphoning out the slurry to make a hole. It looked easier than using a shovel.

Safety wise there will be concerns about the walls eroding into the hole. Some kind of hoist would be needed to retrieve the system but he isn't talking about the depth that a petroleum sample core would require. Likewise, a drilling platform isn't needed to evacuate a sand pit- although the upward force needed for pulling up the PVC tubes might exceed the pontoon rating. I'd solve that with an electric winch anchored to a tree from a safe distance or use a power winch on a nearby truck.

As far as fishing while this is going on.....I'm not sure if fish are going to be hanging out while all of this is happening. Probably would be best to keep your eyes on things before anything unexpected were to happen.


  
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Re: Fine Gold Sluice Design Help Needed ( 22:26:52 ThuFeb 16 2017 )

Fleng,

The last three posts weren't directed to dragline. Often times, I will post information that is directed to the "public at large". :smile:

There are at least two possibilities when drilling or boring a hole into the beach;

The first possibility is that the sand is unconsolidated all the way down to bedrock. In that case, the hole cannot and will not be stable. The sand will continually cave-in and the bottom will probably never appear. My experience in tailings is that the deeper you go vertically, a proportionately larger CONE shaped hole is formed. The sand will assume the "slope of natural repose". The only options are to "case" the hole to bedrock OR suction sand on an unimaginable scale. As the hole reaches the water table, the slope of natural repose approaches near horizontal. A ten foot hole might be 20 feet or more in diameter. using "pie are squared" times depth = 6280 cubic feet of sand to excavate.

The second possibility is that the sand becomes consolidated and will hold its shape. Although this IS preferred for drilling, it is not preferred for purposes of excavating sand surrounding the termination depth - at bedrock.

The show stopper is the case where the bedrock is deeper and the capability to suction sand ends. With a minimal (7 HP) pump, the capability might be at best five feet. A trash pump is not a high performance pump and it is doubtful as mentioned by others that the volume of pumping will attain a reasonable velocity in the selected tubing.

I'm getting ready to shoot a video on elutriation. The thesis is that the pump shown above WILL lift gold ten feet. I will attempt to prove it CAN. :smile:

- Geowizard
[1 edits; Last edit by geowizard at 22:29:23 Thu Feb 16 2017]

  

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