Lost Password :: Posting Pictures :: Who's Online :: Stats :: Memberlist :: Top Posters :: Search
Alaska Gold Forum :: Alaska Prospecting Forum :: Fine Gold Recovery with Magnetic Mats or Magnets in Sluices
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 ]

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

dragline
Offline
671 posts

Reply
Fine Gold Recovery with Magnetic Mats or Magnets in Sluices ( 18:32:04 MonMar 6 2017 )

The purpose for my posting this thread is to engage the forum's members in discussions pertaining to the use of magnetic mats and/or magnets in sluices. It should be noted that as of February of 2017 the patent recently expired for a product that employed magnetic mats in the recovery of extremely fine gold. It is the wish of this forum's owner that all mention of or discussions of that mat be excluded from this thread. Please do not post references to any trademarked names or citations of copyrighted materials in this thread. Thank you.

My first topic of conversation that I would like to introduce into this thread involves the potential use of neodymium magnets in sluices for the purpose of improving fine gold recovery. Some of the forum's members here may have opinions about the validity of such use of magnets but I do not have any such opinions because I have not personally conducted experiments that might help me to understand whether such claims of benefits are valid or invalid.

My purpose in engaging these discussions is to see whether or not there is an interest here among the forum members in exploring experiments that might validate or invalidate some of the claims being made on the Internet and specifically certain YouTube channels. I personally don't have a dog in this race. I have many reservations and see many inconsistencies in certain claims being made such that I have no idea whether those claims are valid. Perhaps together we can engage these discussions and determine the validity of those claims experimentally.

It is not my intention to jawbone for or against these neodymium magnet claims. While some members of this forum may have strong opinions based upon absolutely no experience or experimental evidence I request that all members keep their discussions on this topic civil and constructive. If members are unable to control their comments pertaining to their biases one way or the other I only request that you please be respectful of others with differing opinions or take your discussions to some other thread or forum. Either that or you can design and perform any experiments you believe might help this forum's members determine the validity of these claims one way or the other.

dragline

  
dragline
Offline
671 posts

Reply
Re: Fine Gold Recovery with Magnetic Mats or Magnets in Sluices ( 20:09:44 MonMar 6 2017 )

As I have come to understand, the scientific line of reasoning used to support claims that the use of powerful neodymium magnets may help to improve fine gold recovery in sluices has to do with gold's diamagnetic properties. Suffice it to say there are three forms of magnetism as follows:

Feromagnetism
Paramagnetism
Diamagnetism

While probably everyone here is familiar with Feromagnetism those members unfamiliar with the Para and Dia forms might consider watching this video from the University of California Los Angeles.
Paramagnetism and Diamagnetism

Here is one example of a video posted on a YouTube channel that makes claims about neodymium magnets in sluices being helpful for gold recovery. I have linked to this video at the specific time of 2m 53s where an experiment is performed that illustrates a gold coin sliding down an aluminum angle with a powerful neodymium magnet below. You will see the coin slide freely down the aluminum angle until it arrives just over the top of the neodymium magnet where the gold coin is observed coming to a screeching halt and then progressing very slowly.
Gold Magnets

Effects Of Gold On Spinning Magnet
Neodymium magnet versus Copper Tubing
World's First Electric Generator

Yet another example of an YouTube channel making claims about neodymium magnets being helpful in sluices recovering fine gold follows. I find this YouTuber's claims interesting because the guy seems very convinced that his claims are valid and yet makes no effort to report experimental results or evidence.
Gold Sluicing Using Magnetic Divergent Field Geometry

Again, I have not yet formed an opinion one way or another whether neodymium magnets may or may not be helpful in fine gold recovery. Perhaps you have an opinion? Or, perhaps you might have an idea about how to go about designing an experiment that might test the hypothesis that powerful neodymium magnets might actually help recover gold in sluices?

For a few bucks I will probably order some neodymium magnets for use with my 4-TPI Sawtooth mat so as to perform some tests to see whether these claims might be valid. Here is a layout I did illustrating some 5mm x 5mm x 1mm square N45 neodymium magnets nested in my Sawtooth mat.



Let me know if you have any suggestions or opinions about how I might go about fairly and objectively testing these claims. If you just want to say it'll never work that fine too but please give the other forum members here a rational explanation that supports your claims.

dragline

  
JOE_S_INDY
Offline
1591 posts

Reply
Re: Fine Gold Recovery with Magnetic Mats or Magnets in Sluices ( 23:17:49 MonMar 6 2017 )

Dragline,

Those Neo magnets are amazing things - but - I feel (and here we have a 4 letter word) any magnet (especially a strong one like an N-45 or an N-52 strength Neo one) will simply gather enough magnetic materials (including, but not limited to, Magnetite and Hematite) to create a massive dam across the face of the magnetic field. Pulling every bit of magnetically active material from the sand slurry would probably quickly clog the mat at the site of the very first magnet / magnetic field. (I hasten to say "In my opinion" on that observation there, of course.)

In my simplistic, little boy's mind, riffles work on the vortex phenomenon while magnets work in some other time space continuum (or so it seems).

Oh yes, the Paramagnetism was well known to me - but - Dimagnetism, on the other hand, was all new and crazy! :devil:

Joe :clap:



---
Wiser Mining Through Endless Personal Mistakes
 
 
WmA
Offline
68 posts
Reply
Re: Fine Gold Recovery with Magnetic Mats or Magnets in Sluices ( 23:48:07 MonMar 6 2017 )

The original design that Dragline is going from actually has the magnets placed above the flow of material which would accomplish two things....


The above image is from this video... Which starts at 8:26 so you don't have to wade through the boring beginning.

PART 2: GOLD SLUICING EXTRACTION device using magnetic divergent field geometry

1. It would eliminate the dense clogging effects of the magnetite riffle and provide a kind of soft magnetite curtain.

2. it would still allow the diamagnetic forces to be exerted in a downward angle where it push the gold downward into the sluice, a kind of additional gravity aid.
And it would slow the golds forward movement due to the eddy currents induced.

Here is a video That shows one method of hanging the magnet and what it is supposed to accomplish.

Sluice example

And this video shows a little better what the magnetite curtain would be like.

Highbanker Sluicing with a Magnet Bar


And by the way..... all this theory stuff is WAY above my pay grade....:devil:
[8 edits; Last edit by WmA at 00:31:10 Tue Mar 7 2017]

  
dragline
Offline
671 posts

Reply
Re: Fine Gold Recovery with Magnetic Mats or Magnets in Sluices ( 16:20:05 TueMar 7 2017 )

Joe and WmA,

Both of your observations seem to be very good and critical to a proper magnet-in-sluice design. I can see that my first design proposal failed to address these concerns that you both have raised so I'll have to rethink my first approach and redesign so as to accommodate your very good points. One thing is for sure and that is both of you are making extremely good observations that demonstrate your aptitude and insight into these complex design concepts and I am very grateful for your input.

You will notice that I have indicated that previous layout graphic as obsolete. I am working on a new layout that will place magnets above the slurry. By my now obsolete design having placed the powerful N45 magnets on the riffles of the mat they would capture and accumulate too much magnetite creating large mounds which would become defacto riffle features on the sluice which would not be a good thing.

These larger magnetite mounds-become-riffles would change the laminar flow of the sluice thereby altering the performance of and reducing the efficiency of the Sawtooth mat. Another problem with placing the magnets on the mat as WmA correctly described is the fact that gold's diamagnetic properties would tend to cause the gold to be pushed upwards from the magnets which in this case would be back up apposing gravity and into the slurry... again, not good.

I've decided to do a new layout that accommodates both of your suggestions, i.e. position the magnets in an overhead compartment above the riffles with the slurry sandwiched between the overhead compartment and the riffles. In this overhead configuration the magnets would tend to accumulate magnetite on the flat surface above the slurry.

Overhead magnet layout advantages (restated from your input):

1. With the magnets positioned over the top of the slurry the diamagnetic properties of gold would tend to push the gold away from the magnets which would cause the gold to be pushed down into the riffles where the gold would be captured and retained. Essentially, the powerful magnets would add an additional force vector to the gold that would complement the force vector of gravity, i.e. in a similar respect as if g (gravity) for gold was increased relative to every other non-diamagnetic solids particle in the slurry.

2. With the magnets overhead the magnetic black sands would be attracted upwards and tend to be retained on the smooth top surface of the slurry channel. The magnetite would accumulate on this top surface owing to its feromagnetic attraction to the magnets. As the magnetite accumulated on the top surface the pressure needed to force the slurry thru the sluice would increase to the point that the magnetite would be laid down flat and stripped away by the current reaching homeostasis. After the retained magnetite reached homeostasis (as much magnetite being retained by as leaving the sluice) all magnetite entering the sluice would tend to be attracted up towards the magnets and travel thru the length of the sluice with an anti-gravity force vector bias.

Specification of Magnets: Given I will be generating a new layout that will attempt to position the magnets above the slurry I'll probably need to figure out and specify a different magnet that is optimal for this overhead positioning. In this regard I'd appreciate your input as to what neodymium magnet specifications might be most appropriate for this layout. The only thoughts I have presently regarding these specifications is that I will probably want to choose an N45 neodymium magnet that is square and thin. As to the size of the dimensions of the magnet I do not have any opinion at this and will probably choose a size that is most economical on a dollars per inch basis, i.e. when arrayed across the width of a 12 inch wide sluice (example only) magnets that when arrayed linearly will span the width of the sluice at a low cost while providing enough magnetic field strength to reach down thru a nominal 1 inch deep slurry and penetrate the riffles below.

Conclusion: The above observations and hypothesized outcomes may be proven factual true thru the process of experimentation, or, they may merely be my factually incorrect ramblings resulting from upon my misunderstanding the actual forces and effects that will actually manifest. The only way that I can see to determine what will or will not actually happen will be to design an experiment that tests these hypotheses.

Proposed Experimental Design: This is something we haven't discussed as yet but we should probably start thinking about. A properly designed experiment is essential for reaching valid conclusions thru our testing efforts. In other words, we will need a way to establish a control to which we can compare results with and without the introduction of magnets. The most practical experiment design I can think of would involve have the ability to establish discrete regions of riffles with and without overhead magnets and then evaluate the retained concentrates separately for gold content. In other words, if there were for rows of magnets each at one foot intervals going down a four foot sluice and the 6 inch regions immediately below and above the magnets could be evaluated for gold content separately. If there were no statistically significant difference between these regions the addition of magnets in that experiment would be deemed to be ineffective. If, on the other hand, there was a significant regional difference in retained gold in favor of the magnets the conclusion of benefit would be justified.

dragline

  
Fleng
Offline
147 posts

Reply
Re: Fine Gold Recovery with Magnetic Mats or Magnets in Sluices ( 16:53:06 TueMar 7 2017 )

dragline-
Just a few thoughts here,
-as one who has spent time trying to separate magnets from other magnetic material it is quite time consuming. The separators that are sold for removing black sand are spring loaded with a barrier. This might be needed as turbulence and splashing will undoubtedly leave deposits.
-in trying to determine the best shape and magnetic field intensities it would be very expensive to try different magnets for each experiment. It would be more practical at the outset to use electromagnets of varying shapes to decide what the best configuration for your application. It is easy enough to weld an assembly together and wind coils. The advantage to using an electromagnet is that it can vary in intensity as a function of the dc current and it can be turned off.

  
geowizard
Offline
1521 posts
Reply
Re: Fine Gold Recovery with Magnetic Mats or Magnets in Sluices ( 17:19:54 TueMar 7 2017 )


In 2010, I went through a program called "Design for Six Sigma" at Honeywell.

The importance of Design for Sigma is getting an understanding of the "value" contained in data. Then applying the lessons learned from the data to improve the process.

The first and most important challenge facing dragline or anyone else in designing an experiment is how to capture relevant data. Yes, all of the variables have to be controlled. Then as variables are changed, the EFFECT of the changes in the variables have to be measured.

All of this requires a data acquisition system that is capable of measuring all of the inputs and measuring all of the outputs simultaneously in real time. It isn't trivial. :smile:

- Geowizard

  
geowizard
Offline
1521 posts
Reply
Re: Fine Gold Recovery with Magnetic Mats or Magnets in Sluices ( 17:27:05 TueMar 7 2017 )


Nano particles;

Measuring the forces of Paramagnetism and Diamagnetism on micron and sub micron particles of gold is only done by research institutions that have elaborate tools and research grade facilities.

There are two independent recent research campaigns that are searchable on the internet - with reference to the magnetic properties of GOLD.

One effort is taking place in Japan and the other in the Netherlands. The discovery that has been made is that GOLD is slightly Paramagnetic as well as slightly Diamagnetic. :smile:

- Geowizard

  
dragline
Offline
671 posts

Reply
Re: Fine Gold Recovery with Magnetic Mats or Magnets in Sluices ( 18:24:04 TueMar 7 2017 )

Fleng,

Thank you for your observations and suggestions.

Although I have considered electromagnets as an option for my experiments in the past I ruled them out owing to reports I have heard from multiple sources that electromagnets are not capable of generating the compact high intensity magnetic fields that the higher grade neodymium magnets are capable. I haven't verified these reports as accurate experimentally but I have determined that I consider these reports sufficiently credible so as not to embark on an electromagnet experimentation effort at this time.

But yes, I do have a collection of magnetic separators for separating magnetite from gold, and having played around with those a bit in the past I also have reached certain opinions about how accumulations of magnetite directly upon my magnets would result in all sorts of problems. That's why I stated previously that the designs that I am working on will employ a smooth surface barrier between the magnets and the slurry such that the magnets may be periodically slid towards tails and lifted such that all accumulations of magnetite on the upper smooth surface would thereby fall down into the slurry and quickly flushed to tails.

Thanks for the suggestions.

dragline

  
dragline
Offline
671 posts

Reply
Re: Fine Gold Recovery with Magnetic Mats or Magnets in Sluices ( 18:50:12 TueMar 7 2017 )

Geowizard,

You bring up some excellent points about the six sigma training program. While I haven't been thru formal six sigma training like you have, I was frequently held responsible for providing calculations for verifying three sigma (99.73%) statistical probability for all of my design tolerancing where engineering sign-off was mandatory. But hey, that was many years ago... but not so long ago that I've forgotten the importance of statistical design reviews.

Regarding gold nanoparticles, I had run across a few references to scholarly articles about gold nanoparticles having simultaneous paramagnetic and diamagnetic properties but I dismissed these as irrelevant owing to the fact that nanoparticles would by definition be many orders of magnitude smaller in mass than even the smallest gold particles found on Oregon's beaches. I believe this is a reference to the Japanese study you were also mentioning here:
Clarifying the Hidden Magnetism of Gold (Au) (Press Release)

From my reading of this study it seems that gold almost always displays diamagnetic properties except that these recent studies have determined that gold nanoparticles also display strong paramagnetic properties. While it is unclear from my reading of this research whether gold's paramagnetic properties might become noticeable at typical Oregon beach gold 100 mesh particle sizes, it is an interesting phenomenon to take note of as our experimental results may or may not be influenced by this property (however I'm guessing not).

dragline
[1 edits; Last edit by dragline at 18:56:15 Tue Mar 7 2017]

  
dragline
Offline
671 posts

Reply
Re: Fine Gold Recovery with Magnetic Mats or Magnets in Sluices ( 20:25:27 TueMar 7 2017 )

Okay guys,

I am proceeding with my efforts to specify a neodymium magnet for these experiments. So far I've determined that the prices of neodymium magnets are directly proportional to their mass with another smaller pricing influence related to the field strength. In other words, an N35 neodymium magnet is going to be about 15% to 20% cheaper than an N52 magnet from the same supplier.

I have engaged communications with a few Chinese neodymium magnet distributors and I have determined that I can have the exact magnets I choose manufactured to my specifications at a cost that is roughly related to the total neodymium iron boron kilogram weight for the order. If the cost of extremely small magnets are considered there is an additional premium paid for larger quantities and the fact that there is a higher cost for the nickle coating relative to increased surface area to volume for smaller magnets.

My best price point for a custom order occurs at between 10 and 15 kilograms total order Nd2Fe14B weight with a cost of roughly US$400 to US$500 including express courier shipping. Given a specific gravity for Nd2Fe14B is about 7.4 g/cc my proposed 100mm x 20mm x 10mm N45 magnets would entail a volume of 20cc and a weight of approximately 148 grams (5.22 ounces). The total Nd2Fe14B weight for an order of 100 such magnets would come to about 14.8 kilograms. Shipments heavier than about 20 kg gross generally have increased customs issues including the requirement for brokerage. So if I can keep costs and weight to modest levels I should not likely experience any clearance problems or delays (but you never know).

I am not worried about this specific magnet not being the exact size or strength that ultimately proves most successful in this application because I'll easily be able to sell them on eBay at a profit should my efforts here prove unsuccessful.

Regarding the specification of field orientation there would be two different configurations available for this magnet...
1. Major Flats
2. Major Ends



Of these available choices Major Flats will most assuredly yield the best performance by far.



dragline

  
geowizard
Offline
1521 posts
Reply
Re: Fine Gold Recovery with Magnetic Mats or Magnets in Sluices ( 14:23:01 WedMar 8 2017 )

dragline,

Excellent illustrations. :smile:

Because Gold is weakly diamagnetic, the forces of gravity and the forces of water/slurry flow need to be lower than or less than the magnetic forces involved. That is to apply the rules of "proportional forces" to work in relatively equal amounts. My concern is that the forces of flow and gravity are much greater than the weaker magnetic effect.

As technology advances, it may be possible that magnetic properties of gold can be exploited to make things possible that are not currently within our reach.

- Geowizard

  
Fleng
Offline
147 posts

Reply
Re: Fine Gold Recovery with Magnetic Mats or Magnets in Sluices ( 19:52:54 WedMar 8 2017 )

Actually dragline the field intensities of electromagnets are capable of far more than field magnets. It is all in the design.

Want more? Just add turns or current. The limiting factors are the size of the conductors and the magnetic material. One thing I learned in my studies at the National High Magnetic Field labs is that the strongest magnets are often made of steel because the forces are so high. Hybrid magnets may use a superconductor inside of a second copper wound magnet. Interestingly, the core of these solenoids are used to create the strongest field magnets.

BTW-$500 is way too much to pay for field magnets. For that much cash a lifetime supply could be had several times over.


null [7 clicks] Ebay magnets for less

  
dragline
Offline
671 posts

Reply
Re: Fine Gold Recovery with Magnetic Mats or Magnets in Sluices ( 00:33:20 ThuMar 9 2017 )

Geowizard,

You are correct about the forces of gravity being much greater than the forces of the diamagnetic repulsion forces of gold in a strong magnetic field. The forces of slurry pushing the gold further down the sluice and eventually to tails is also much greater than the diamagnetic repulsion forces of gold. However, whether or not strong magnetic fields increase the recovery of gold are not exclusively bound to the relationship of which competing force is greater than the other. Any increased force pushing the gold downward into the riffles will increase the likelihood for gold being captured. The question is "how much" these diamagnetic forces contribute to increasing gold's rate of capture.

But there is a much more significant force introduced by the magnets that is not being described by simple diamagnetic repulsion forces. Having played around with these N52 neodymium magnets and gold coins I can tell you with confidence that the strongest force a play here is that of diamagnetic breaking. This is the force that grabs onto gold and slows its velocity as it passes thru a strong magnetic field. If you haven't experience or witnessed this force first hand you might know have an appreciation for how powerful this force is. This diamagnetic breaking force is much stronger than the forces of diamagnetic repulsion perhaps by several orders of magnitude when gold moves at high velocity. The faster a particle of gold attempts to move thru a powerful magnetic field the greater the breaking forces.

The thing that I have no clue about is whether these diamagnetic breaking forces might have any effect on the gold capture rate. Perhaps it does oer perhaps it doesn't. One might assume that the diamagnetic breaking force will act omni-directionally such that the forces of gravity are braked just as much as the downward flowing velocity such that the path or vector thru the sluice is unaltered except for a decreased velocity. Answering these questions, in part, are what I hope to accomplish with this experiment.

dragline

  
dragline
Offline
671 posts

Reply
Re: Fine Gold Recovery with Magnetic Mats or Magnets in Sluices ( 00:45:26 ThuMar 9 2017 )

Fleng,

Perhaps you are correct about the possibility of incorporating electromagnets in these efforts in stead of high grade N52 neodymium magnets. The problem or me is that I am not an electrical engineer nor would I consider myself competent to be playing around with high current electromagnets in saltwater environments. But you are probably correct that some expert in magnetic field engineering might be able to design an electromagnet array that competes with or might be superior to permanent neodymium magnets in this application. It just isn't an experimental development effort that I feel competent pursuing. Perhaps at some point in the further when I have come to understand whether or not these neodymium magnets might yield a successful strategy I will take up the electromagnet challenge you propose.

If you don't mind, could you send me a link to an electromagnet on eBay that you believe might offer similar or perhaps greater potential for success as the neodymium magnets I am currently pursuing?

Thanks!

dragline

  
geowizard
Offline
1521 posts
Reply
Re: Fine Gold Recovery with Magnetic Mats or Magnets in Sluices ( 01:00:55 ThuMar 9 2017 )

dragline,

The braking effect that you refer to is "Faraday Braking."

The effect is caused by a metal object moving in a magnetic field. An electric current is induced into the metal. It happens that the electric current creates a secondary magnetic field. The secondary magnetic field opposes the primary field. The effect is enhanced by increasing the relative motion. That's the reason for the increased braking at increasing speed or increasing relative motion.

- Geowizard

  
geowizard
Offline
1521 posts
Reply
Re: Fine Gold Recovery with Magnetic Mats or Magnets in Sluices ( 01:09:59 ThuMar 9 2017 )

dragline,

A couple of references on magnetic braking:

https://en.wikipedia.org/wiki/Eddy_current_brake


http://mafija.fmf.uni-lj.si/seminar/files/2007_2008/BRAKING_MAGNETIC.pdf

Note, the braking is seen in "non-magnetic" metals.

- Geowizard
[7 edits; Last edit by geowizard at 01:28:21 Thu Mar 9 2017]

  
dragline
Offline
671 posts

Reply
Re: Fine Gold Recovery with Magnetic Mats or Magnets in Sluices ( 04:58:09 ThuMar 9 2017 )

Geowizard,

Yes, exactly. Magnetic breaking is understood to be caused by electrical eddy currents that are generated in conductive materials (metals usually) when a magnetic field moves near the conductive object, or visa versa.

This phenomenon is explained with the application of Faraday's Law and Lenz's Law. It is not difficult to understand how this happens with gold but it should be understood that gold's diamagnetic properties have nothing to do with the fact that gold is susceptible to magnetic breaking.

Here is a short video that illustrate the principle of magnetic breaking.
Magnetic Braking: Whack the Pig

dragline

  
geowizard
Offline
1521 posts
Reply
Re: Fine Gold Recovery with Magnetic Mats or Magnets in Sluices ( 13:02:07 ThuMar 9 2017 )

dragline,

So, the braking force on micron gold could be calculated.

The force in Newtons (SI units) would be on the order of one nano Newton? :confused:

- Geowizard

  
geowizard
Offline
1521 posts
Reply
Re: Fine Gold Recovery with Magnetic Mats or Magnets in Sluices ( 14:44:06 ThuMar 9 2017 )


Various "forces" are at work and play in a sluice! :smile:

What is force? :confused:

According to Newton's second law of motion;

Force = Mass x Acceleration (F = M x A)

Most of us are smarter than a Fifth Grader and we know how to solve multiplication problems. Right?

Gold has "Mass".

Gold has a Mass of 19.38 Grams per cubic centimeter. So, a cube of Gold that measures one centimeter by one centimeter by one centimeter weighs 19.38 Grams.

The Force of Gravity is approximately 9.8 newtons. One kilogram (1000 Grams) exerts a Force of 9.8 newtons.

Since we know how Force can be calculated, we can calculate the forces at work and play in a sluice box! :smile:

- Geowizard

  
geowizard
Offline
1521 posts
Reply
Re: Fine Gold Recovery with Magnetic Mats or Magnets in Sluices ( 15:54:09 ThuMar 9 2017 )


Water, Gold and Magnetism;

The forces at work and play in a sluice box involve the relative masses of water, Gold and in this case, Magnetism.

In the most simple terms, it has been shown that the Magnetic Braking force will slow a rolling gold coin that is rolling along an aluminum rail.

The same demonstration applied to a gold coin falling in free-fall vertically past the magnet would have no visible affect. The braking affect IS visible on a slight decline because the force of gravity is being applied to a coin at a slight angle and the effective force of gravity is related to the cosine of the angle.

A simple demonstration could be made with micron gold sliding along a rail in the place of the coin. :smile:

- Geowizard

  
geowizard
Offline
1521 posts
Reply
Re: Fine Gold Recovery with Magnetic Mats or Magnets in Sluices ( 16:28:57 ThuMar 9 2017 )


So, if 1 Kilogram exerts a force of 9.8 newtons;

Then one gram exerts a force of 9.8 milli-newtons.

And... one milligram exerts a force of 9.8 micro-newtons.

Finally, one microgram exerts a force of 9.8 nano-newtons! :smile:

- Geowizard

  
geowizard
Offline
1521 posts
Reply
Re: Fine Gold Recovery with Magnetic Mats or Magnets in Sluices ( 17:19:28 ThuMar 9 2017 )

"Beach Gold";

Is Oregon Beach Gold "special"? :confused:

From certain sources, I have learned:

Nome, West Beach Gold runs 50 to 500 microns. Using a mean of the extremes, we get 275 microns.

Nome, East Beach Gold runs 70 to 300 microns. Using a mean of the extremes, we get 185 microns.

Lincoln City Oregon Beach Gold runs 70 to 250 microns. Using a mean of the extremes, we get 160 microns.

Waldport Oregon Beach Gold runs 50 to 150 microns. Using a mean of the extremes, we get 100 microns.

In the process of designing a magnetic recovery system, the forces need to be understood. Having a definition of the size of the Gold involved in the process allows us to determine the relative forces involved.

Knowing the size of the gold in microns, we can calculate the mass (weight) of the particles of gold and then develop an understanding of the Forces! :smile:

- Geowizard

  
Fleng
Offline
147 posts

Reply
Re: Fine Gold Recovery with Magnetic Mats or Magnets in Sluices ( 17:36:41 ThuMar 9 2017 )

Geo:
It is a little more complicated than that.
Newton's gravitational constant is actually Newton-meter squared divided by kilogram-squared. This is the acceleration on the mass that produces the force. In this case the static down force due to gravity.

But there are other forces at work in this case such as the water and sand pressure, turbulence, and buoyancy effects from air bubbles.

Then we have the conservation of momentum from the steady flow of mass. This is where the magnetically-induced breaking will have an effect.


  
Fleng
Offline
147 posts

Reply
Re: Fine Gold Recovery with Magnetic Mats or Magnets in Sluices ( 17:59:35 ThuMar 9 2017 )


dragline:
Here is an electromagnet that the seller claims can be used in an ocean environment:
ebay

It sells for $46.70 with free shipping. Based upon the electrical requirements (589lbs@12V or 634lbs@24VDC) I'd recommend plenty of waterproofing of the wiring. The size is close to what you are looking for: 4" x 3.25" on the face. This was probably a security door lock system if I had to guess. The holding force is bases upon a similar shaped permanent magnet. The diamagnetic braking force on a spec of gold will be far less. :smile:


This coil is rated at 5.4 ohms so a power supply would need to supply 2.2 amps @ 12v or 4.4 amps at 24V.
To give you an idea of the power drain: This is 26.4 watts or 105.6 watts (amp hours). :smile:
Bottom line is that when you triple the power you only increase the holding force by 11%.

  
geowizard
Offline
1521 posts
Reply
Re: Fine Gold Recovery with Magnetic Mats or Magnets in Sluices ( 18:28:56 ThuMar 9 2017 )

Fleng,

I'm trying to work into this GENTLY. :smile:

So, as to not get into controversy over the gross dynamics - I was covering each force individually for clarification. If we put a boiler box together FIRST and then disassemble the forces - it makes things much more complicated.

(As a side bar - I didn't say gravity was the only force.)

(As a second sidebar: 1 newton = 1 kilogram-meter/second squared.) So, it's NOT newtons per kilogram/ meter squared.

- Geowizard
[1 edits; Last edit by geowizard at 18:38:51 Thu Mar 9 2017]

  
geowizard
Offline
1521 posts
Reply
Re: Fine Gold Recovery with Magnetic Mats or Magnets in Sluices ( 19:52:29 ThuMar 9 2017 )

Magnetomotive force;

If an electromagnet is used, the force is referred to as "magnetomotive" force.

Calculation:

F = NI . N = the number of turns in the electromagnet and I is the current in Amperes.

The force is expressed in newton-meters.

If you DOUBLE the current, the Magnetomotive Force DOUBLES. :smile:

- Geowizard

  
geowizard
Offline
1521 posts
Reply
Re: Fine Gold Recovery with Magnetic Mats or Magnets in Sluices ( 20:23:36 ThuMar 9 2017 )

An electromagnet in your sluice?

The beauty of electromagnets is that you can roll your own and you can control the magnetic intensity and you can reverse the poles without moving the magnet!

Control of the magnetic intensity is easy. All that needs to be done is to vary the current through the electromagnet!

How?

"Electronics" :smile:

Current can be controlled using a power transistor. Mosfets and other devices can also be used to control current.

So, knowing the magnetomotive force that is needed, given a DIY magnet, a power source, and a few parts, you are ready to go!

Electromagnets came under discussion on the forum - back when we were discussing Bering Sea Dredges. A simple electromagnet can be fabricated using insulated wire and a nail. Want a BIG magnet? Use a BIG nail. Want a stronger magnet, use a bigger power source and drive more current through the magnet! Wind the wire around the nail. More windings (turns) the stronger the magnet.

CAUTION: Avoid high voltage and high current!

Under 40 volts, keep one hand in your pocket. Over 40 volts, keep both hands in your pockets! :smile:

- Geowizard

  
geowizard
Offline
1521 posts
Reply
Re: Fine Gold Recovery with Magnetic Mats or Magnets in Sluices ( 20:33:15 ThuMar 9 2017 )

What? You want FIFTY electromagnets across your sluice? :confused:

Run out to the shed and grab a bag of nails and a spool of magnet wire!

Take the first nail and wind 20 turns of wire on the nail. Leave a length of wire to hook up the power source then wind the wire on the first nail. Leave a few inches and wind 20 turns on the next nail. By now you get the idea. Wind twenty turns on all FIFTY nails.

When you're done...

You have constructed a series of electromagnets that will produce a magnetomotive force of 1000 ampere-turns! :smile:

- Geowizard

  
geowizard
Offline
1521 posts
Reply
Re: Fine Gold Recovery with Magnetic Mats or Magnets in Sluices ( 21:07:10 ThuMar 9 2017 )

Now what? :confused:

So, one of our members, Joe suggested a potential problem is that the design (using neodymium magnets) would catch Black Sand!

Using the array of electromagnets that were fabricated above, we can carefully pound the nails into a piece of 2x4 so that the nail heads are at the same height...

And attach the electromagnet to the top of our sluice - underneath with the nail heads pressed against the bottom!

The electromagnets will catch the black sand BEFORE it gets to dragline's neodymium diamagnetic sluice! :smile:

- Geowizard

  

Pages: [ 1 2 ]

[ 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 07:44:12 Tue Oct 24 2017

    Powered By BbBoard V1.4.2
    © 2001-2007 BbBoy.net
    Alaska Gold Forum :: Alaska Prospecting Forum :: Fine Gold Recovery with Magnetic Mats or Magnets in Sluices

    [Most Recent Quotes from www.kitco.com]

    [Most Recent Quotes from www.kitco.com]