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dragline
22:26:11 Mon
Feb 27 2012

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Saw-Tooth Mat

I'm looking for a mat with a fine saw-tooth pattern, the finer the better. Has anyone here seen or heard of such a mat and know where I can find it? Here's a picture of what I had in mind...


For both economy, flexibility and durability the best material to use would probably be a synthetic rubber like EPDM (ethylene propylene diene monomer [M-class] rubber).
http://en.wikipedia.org/wiki/EPDM_rubber

In the past I have purchased 100 foot rolls of the more commonly available square or V-ribbed corrugated rubber runners...
http://www.barcoproducts.com/store/item.asp?ITEM_ID=762

But I have a specific need for a saw-tooth runner matting and was hoping that one of you might be able to point me in the right direction.

dragline

  
JOE_S_INDY
00:40:54 Tue
Feb 28 2012

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Re: Saw-Tooth Mat

Gold Hog will be having a rubber carpet - "UC" coming out in a month or so. Goldhog.com will get you started.

There are many videos there to see - at least good to know about.

I take it that you are looking to recover seriously tiny Gold. Just a feeling. Gold Cube, G-1, Le' Trap, Cal Sluice and others should be looked at.

Do a lot of internet searching for the newer equipment that can hold the very small 'stuff'. You will have to get something which will work for your (secret) location.

Great to see you posting again!

Joe



---
Wiser Mining Through Endless Personal Mistakes
 
 
overtheedge
02:05:44 Tue
Feb 28 2012

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Re: Saw-Tooth Mat

If worse come to worse, you can make your own with Devcon Flexane Trowelable. I would use a fiberglass or nylon scrim for backing. Even plastic window screen would work.

Take a finishing trowel and file the shape of the teeth you need.

I've had lots of success with just the heavy rubber V-rib for fine gold. I do have to clssify < 1/4".

  
dragline
02:27:45 Tue
Feb 28 2012

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Re: Saw-Tooth Mat

Joe,

Thanks. I've watched several hours of Gold Hog videos but I am not aware that Doc is planning on making the specific mat that I'm looking for. I will make it myself if I can't find it already in production.

Utilizing Electrical Discharge Machining (EDM) with potentially sub-micron accuracy almost microscopic details are becoming practical.
http://www.mmsonline.com/articles/machining-to-sub-micron-accuracy--with-edm
http://en.wikipedia.org/wiki/Electrical_discharge_machining

Of course more affordable EDM machining in common practice allow for the machining of highly precise EPDM extrusion dies with a range of wire feeds from 0.001 to 0.004 inches in diameter. The achievable inside radius for these tooling dies is typically about 1.5x the wire diameter and dimensional accuracies can approach 3 microns.

I predict that it is only a matter of time before some enterprising designer comes up with a novel approach to fine gold recovery and/or concentration based upon these almost microscopic machining technologies.

The concept I'm playing with presently involves utilizing EDM machined tooling to extrude a mat pattern, sort of like what Doc from Gold Hog is attempting, but with a saw-tooth pattern scaled down one or two orders of magnitude. But yes, the purpose would be to create a material capable of efficiently capturing and retaining -100 mesh gold. I understand that there are really very few instances in which such a technology, assuming it would actually work, might be put to practical use.

Imagine a saw-tooth patterned mat with 32 to 64 teeth per inch. I'd be happy to find an already available saw-tooth mat with just 4 to 8 teeth per inch to test my theories in the lab and if you are aware of anything like my descriptions please post a link.

My "secret" location is now Roseburg, Oregon, close enough to the coast to play in the beach sands occasionally.

Thanks.

dragline

  
dragline
02:38:49 Tue
Feb 28 2012

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Re: Saw-Tooth Mat

overtheedge,

The saw-tooth pattern of the mat that I am contemplating is essential to its function for a variety of reasons. A simple V-wave or Square-wave mat pattern won't work for my purposes at all. The pattern itself must be asymmetric. This is an active, not passive, geometry and I am hoping to find an existing saw-tooth patterned mat already fabricated of any dimension, but the smaller the better. I've looked for such asymmetric patterned mats over the years and not found any. Again, the pattern is very specific to my intended uses and assuming that no one in this forum has ever come across such a mat I will manufacture it.

But as always, I really appreciate your suggestions.

dragline

  
dragline
02:44:05 Tue
Feb 28 2012

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Re: Saw-Tooth Mat

overtheedge,

I really do like your suggestions. I could start with an actual saw blade, like an extremely fine hack-saw blade and then as you say use it to scrape that saw-tooth pattern in the Devcon Flexane Trowelable. That's an awesome idea for prototyping my designs. Now all that I need to find is an extremely finely toothed hack-saw blade.

Thanks!

dragline

  
dragline
02:58:51 Tue
Feb 28 2012

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Re: Saw-Tooth Mat

Here's a pretty fine saw tooth pattern, 42 teeth per inch.


  
dickb
04:31:06 Tue
Feb 28 2012

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Re: Saw-Tooth Mat

I would expect that a CNC horizontal mill should be able to produce negative aluminum molds in a size about 6" x 24" overall with the notches running the 24" direction. They could be produced to interlock to make mats that are 24" x 48" that can be used as mold forms with 10 groves per inch.

That may be a solution.

Dickb

  
echidnagold
06:52:55 Tue
Feb 28 2012

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Re: Saw-Tooth Mat

The only advantage to matt like that is the quick clean up and quick visual inspection, low engery pop and son style with very fine mesh will do better and a whole heap cheaper, clean up is a major bitch though!!

I'm only going off personal experiance with the keen miracle style matt, its good and I love it but it's not as good as fine mesh over carpet / moss / coroury(sp). Again just my personal exp..







  
dragline
16:26:15 Tue
Feb 28 2012

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Re: Saw-Tooth Mat

echidnagold, Your observations are entirely correct but only assuming that my intended use for this saw-tooth mat is as you describe. It isn't. Because my application is somewhat novel I'll refrain from letting the cat out of the bag until I have experimental evidence that it actually works.

dickb, Yes, I've thought about having a conventional milling tool made with a given saw tooth pattern at from 10 to 40 teeth ground into the cutting edge per inch. That way any good CNC mill could step and repeat whatever pattern that was cut or ground into the cutting edge of the tool. Aluminum is frequently used for extrusion and embossing dies for thermoplastics but I only have limited experience with web processing and extrusion tooling. Typical web widths for these applications commonly start at about 60 inches wide with some manufacturing lines capable of up to 120 inches. Glass fiber, nylon cloth and/or spun polyester backings are available to increase the durability, stability and strength of these laminations during processing and use (probably a good feature).

But I sure wish there was a saw-tooth mat already being manufactured by someone. That way I wouldn't have to go through all this fabrication R&D. I understand completely why there probably isn't such a thing already in existence. A saw-tooth pattern probably is not a particularly efficient scrubber mat for foot traffic and it isn't a particularly good design as a riffle design for fine gold sluicing either.

dragline

  
overtheedge
16:50:08 Tue
Feb 28 2012

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Re: Saw-Tooth Mat

Dragline. for teeth that fine, I don't think the trowelable Flexane will work directly. In other words, you probably won't be able to make such small teeth with the trowel.

Using the Flexane Trowelable you will probably need to make a negative and use a release agent. Can you spell plaster of paris? Oh I know; horribly low and old technology. For release, you could try PAM cooking oil spray (canola oil). The mould only need to be a skintch deeper than the riffles. Make the mould on a piece of plywood to whatever size you need.

Devcon also make a pourable Flexane that might do the trick. I don't have any experience using the pourable, so I'm only guessing on its suitability.

But I would try it on a small scale first if you can't find a source for your mat.

One other possibility is the flexible pick-up bed liner coatings such a "Herculiner". If you need the bedding to be somewhat flexible, coat a canvas tarp.

Don't forget the use of fleece blankets. They are a bear to clean, but snag gold it does. So does a burlap bag.

Very carefully. Put down the coffee cup and step away from the thermos. I have obviously had too much coffee.

  
dickb
17:20:40 Tue
Feb 28 2012

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Re: Saw-Tooth Mat

With prototype design, small scale is the only viable course. You need to be able to make the necessary changes to develop the design in a cost effective way.

I'm trying to follow the train of thought your on and I'm not sure rubber compounds will be the best solution. Cast resins with additives may be your best option. When you start to approach nano dimensions,flexibility can ruin the objective.

Dickb

  
dragline
19:37:32 Tue
Feb 28 2012

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Re: Saw-Tooth Mat

Dickb,

Fortunately, I'm not working with nanotechnology yet. But when you think about materials with differential friction coefficients for gold versus mineralized sands and silica you really are getting into the nano scale factors concerning weak molecular forces at very close distances.

For a variety of reasons I don't know yet whether a material that is sticky to gold and yet slippery to black sands, or visa versa, would be optimal for my intended applications. From my previous experiments with EPDM and similar polymers I know that these rubbery materials are reasonably sticky to gold. Most cast resins and thermo plastic polyethylene resins are slippery to gold and more typical for such molded sluices like the Le Trap sluice and the huge variety of molded gold pans you see on store shelves.

My guess is that the more ideal material for my application would be slippery to gold and everything else, like polyethylene thermoplastics, but I can't reject synthetic rubbers owing to their economy of web process manufacturing and their adaptability and flexibility under a huge variety of design applications.

Back to the lab for more experiments.

dragline


  
trnelson
18:45:12 Thu
Mar 8 2012

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Re: Saw-Tooth Mat

Dragline, if you live in Alaska you can try Alaska Rubber & Rigging. I have bought matting from them before of various coarseness. I have seen the sawtooth matting once before but I can not remember what the website was. The traditional V matting works quite well and I doubt a raked angle would improve much, but that's just my theory.

Keywords to use to search for that sort of matting:
"traction mats" "ribbed mats" etc.

Oh and definitely try McMaster-Carr.
http://www.mcmaster.com/#catalog/118/2091/=gkr6b9

  
overtheedge
07:47:48 Fri
Mar 9 2012

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Re: Saw-Tooth Mat

Well I'm gonna tell my age a bit more, but long ago (40+ years) in a far away galaxy (okay it was Oregon, but it is still far away), I took some college courses in auto-diesel tech and for an elective I took machine tool principles.

One supposedly obsolete tool we had was a shaper. Yeppers that old ram driven single toothed cutter whiz-bang. The instructor was an old machinist that loved old technology. Anyway, you can plane a surface with a 50 piece of steel ground to the shape you want to cut with. The ram cuts a groove and the table sets over a bit for the next ram stroke. Shape the cutter to the tooth design and adjust the set over to give the spacing you need.

When you are done, you have either the grooved bed or use it as a negative mould.

The cutter bit doesn't care what the material is as long as it is rigid enough to cut a groove in. So you could use a plastic.
eric

  
dragline
16:04:57 Sat
Mar 10 2012

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Re: Saw-Tooth Mat

TRNelson, the variety of patterns on those McMaster mats are diverse, but nothing that I've seen so far there or anywhere else would come close to working for my intended application.

overtheedge, having worked for 20 years as a tooling engineer I had the occasion to work with a company back in 1983-1984 that used an acid etched knurling technique to replicate a curvolinear surface into embossing rollers 48, 60, 72 and 80 inches wide. The patterned embossing rollers were then used to manufacture an aluminized mylar and PVC laminate intended to act as an efficient projection display screen for 3D movies and hi-tech military simulators. Unfortunately the inaccuracy of the embossing rollers compounded with non-uniform thermoplastic variables at the embossing nip resulted in the manufacture of reflective PVC laminate sheets that did not appear optically homogeneous or uniform (the displayed images didn't look good).

If no one here on the Alaska Gold Forum knows of a manufacturer of a currently produced saw-toothed mat then my assumption is that such a saw-toothed mat is not likely in current manufacture. The embossing rollers I would need to produce a saw-toothed mat would be considerably easier to fabricate than the curvolinear surfaced embossing rollers I worked with back in the 1980's. An embossing roller for a saw-toothed mat could be chucked on a 14" CNC lathe and the roller teeth could easily be cut in a matter of minutes (not too expensive). All I would need to get started was a run of the mill flat roller that I could then have cut with my intended saw-tooth pattern.

But as you can imagine an undertaking of this scale will not be cheap and if my intended use doesn't pan out I will probably be down at least $20K or more for my efforts. But my confidence is high and the only major obstacle I have moving forward is locating a manufacturer capable of producing this saw-toothed mat economically.

The drawing below exemplifies a typical saw-tooth patterned mat the inverse of which would need cut into a roller and then used to manufacture 2 to 3 tons of material at the first production run.



If anyone here might have any ideas regarding a manufacturer I might contact that could help me manufacture my saw-toothed mat please let me know.

dragline


  
peluk
20:40:17 Sat
Mar 10 2012

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Re: Saw-Tooth Mat

Dragline,is it possible to take Keene Miracle Mat,cut out sections matching your pattern,butt them together and create a workable substitute for testing purposes?
I just went to there catalog for a closeup since my Keene mats are under snow.It looks like it would work and although you would have to lay out about $250 for a mat to cut up,it would be far less expensive than the alternative you are discussing.They could be bonded to a sheet of whatever and set in a sluice bed.

  
peluk
20:43:35 Sat
Mar 10 2012

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Re: Saw-Tooth Mat

Sorry..that should have read "their catalog" not "there catalog".Sister Mary Applecart would smack my knuckles if she caught that one.

  
cubsqueal
01:47:51 Sun
Mar 11 2012

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Re: Saw-Tooth Mat


About 20 years ago I made some castings using Por-A-Mold and Por-A-Kast.

The Por-A-Mold at that time was unbelievable material after curing. I guess it has since been improved. I just pulled out the original mold (about 3" thick) and it is still tough as nails, yet flexible. It is just like a strong rubber. A person can, of course, use Por-A-Mold to make the mold, and then use Por-A-Mold again as the casting material, while using the recommended parting material.

I don't see why a person couldn't make a bunch of "rubber" castings off of the one "rubber" mold. Comes in soft, medium, hard.

One source:

http://www.artmolds.com/product_details.cfm?product_id=196&page=0&cat_name=Resin%20-%20Urethanes

  
dragline
04:16:53 Sun
Mar 11 2012

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Re: Saw-Tooth Mat

Peluk, thanks for the referral to the Keene Miracle Mat. It appears to be an interesting EDPM Rubber extrusion, simple and yet effective as an integrated primary recovery riffle design. It does seem likely that Keene's pattern design will work quite well for its intended purpose as a primary recovery riffle mat. I suppose that the secondary saw-tooth like riffles could be cut out while discarding the larger riffles. The smaller riffles could then be glued together into a continuous saw-tooth sheet. Yes, and I suppose that it might work for what I'm trying to accomplish but it would in no way be ideal. The problem is that the steeper slope of those smaller riffles is not nearly vertical enough for my needs. But it is something to think about and consider.

CubSqueal, that Por-A-Kast polyurethane resin looks very interesting. For making a few prototype sheets it might be the ideal material. The hard formulation specifically looks to be very tough and would likely last a long time even when ravaged by rapidly moving slurries. But notice the price, $169 USD for just 2 gallons. At a specific gravity of 1.06 (for the hard) that would be about 17.7 pounds polyurethane resin. The cost per pound, therefore, would be about $9.55 USD.

Raw materials like thermoplastic EPDM (M-Class synthetic rubber) currently cost between $1,200 and $1,400 per metric ton and most generic PVC resins are now between $1,000 and $1,200 per metric ton, or something close to 55 per pound for either one (plastic prices rise as the price of a barrel of oil rises). Im not an expert on these materials but my guess is that EPDM rubber is every bit as resistant to abrasive slurries as the polyurethane resins of those Por-A-Kast kits. Although for my intended purposes abrasion resistance is extremely important.

Excellent suggestions! Thank you.

dragline

  
trnelson
10:23:56 Sun
Mar 11 2012

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Re: Saw-Tooth Mat

Dragline, I think I found what you're after. This is the link I saw months ago.

http://www.goldhog.com/sluice_mats.htm

Hope that helps.

  
dragline
00:34:47 Mon
Mar 12 2012

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Re: Saw-Tooth Mat

TRNelson, yes, thank you. I have watched a few Gold Hog videos. I appreciate all the experimental trial and error videos that the Doc has published on Youtube, kind of like airing his laundry in public. You can see his transformation of experimental discovery over the months in his videos but his latest design in riffle mats, the Wild Boar Scrubber Mat, appears to be a step backwards (IMHO) from his previous and better design, his Little Hog Under Current Mat.

Compared to Keene's Miracle Mat these Gold Hog mats will probably function competitively. But there probably won't be a huge performance difference between any of these mats and a well designed and tightly assembled expanded metal sluice. But for individuals that don't have the time or experience necessary to construct an expanded metal sluice I suppose one could save a little time and effort by utilizing any of these extruded mats.

The biggest advantage with an extruded riffle mat versus an expanded metal sluice is that cleanup will take much less time because there is no Nomad, Wayfarer or Cactus mat to break down or clean and the sluice concentrates potentially will involve a lot less non-gold concentrates.

The biggest problem that I see Doc having with all of his Gold Hog mats and the lesson he apparently hasn't learned yet regards his lack of experimental planning an discipline. He has set up a perfectly good gold recovery laboratory with excellent equipment and video documentation but he fails to utilize quantitative planning and result analysis effectively. What Doc should do differently is accurately test his mats versus expanded metal or the competitor's mats for specific and very narrow mesh sizes of placer gold under a variety of flow conditions, like Prof. C.W. Poling and Mr. J.F. Hamilton did with their experiments in expanded metal fine gold recovery at the University of British Columbia back in 1986.

See...
http://www.hecklerfabrication.com/files/fine_gold_recovery_sluiceboxes__Poling.pdf

A completely worthless placer gold recovery experiment is one in which after the results are in the experimenter declares that their design or apparatus catches 100% of the fine gold. When it comes to fine gold no apparatus catches 100% and no gold recovery experiment is valid unless it quantifies gold recovery losses. In other words, don't tell me how much gold your device or apparatus catches, tell me how much it loses.

dragline

  
trnelson
09:58:54 Mon
Mar 12 2012

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Re: Saw-Tooth Mat

Well said dragline. With that thought in mind, I'd just like to say not all creeks have 'fine' gold. I have panned on several drainages that produce only large, more chunky gold. I have also learned that flat pieces of gold are much harder to catch in a sluice or gold wheel than dust due to the effects of the water on the larger, thinner surface area. Think of a paper plate in a field of grass on a windy day versus the same plate shredded into a thousand bits.

I would also like to remind you what Steve from AMDS has said about production. While chasing that 1% you will always lose production. When you have to spend 4x as much money and mine at half the yardage to get closer to 100% recovery, the other guy is making way more money overall ignoring that 1%. Just like the old timers with wooden poles for riffles. And they ran down the sluice box, not perpendicular. They still got ninety something percent with little effort or investment. Regardless of the price of gold, chasing the last few percent can be all the difference between profit and bankruptcy.

The fancy rubber mat designs cost a lot more, do not hold as much gold, and absolutely will not outlast expanded metal over astro turf. As the rubber of the mats wear down from abrasion the recovery goes into the toilet.

  
dragline
20:16:24 Mon
Mar 12 2012

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Re: Saw-Tooth Mat

TRNelson,

I couldn't agree with you more concerning the fine gold myth. Only a very few gold mining operations actually have sufficient amounts of fine gold to justify the loss of productivity that might be necessary to capture that extremely fine gold. It doesn't make sense to spend a lot more money and effort to screen your ore to a fine mesh and process a lot less material just to net a few percent more fine gold. Like you say it would be much better to process four times the ore while suffering a small loss in fine gold recovery.

As a general rule the steeper the gradient of a stream or river the higher the percentage of coarse gold. By the time a river slows down and the gradient approaches zero or meets the sea fine gold predominates. Of course there are exceptions when the source of the gold is fine where modern high gradient streams and rivers cut through ancient tertiary river beds (or ore bodies) with very fine source gold (ex. Snake River gold).

This balancing act between fine gold efficiency versus overall coarse gold productivity actually has absolutely noting to do with my present designs or concerns. However, something you said does concern me greatly. You said that these rubber mats will wear down from the abrasive effects of the slurry thereby reducing their recovery. Do you have any concrete evidence or experience to support your assertion?

I am very interested in finding out whether you or anyone here on the Alaska Gold Forum has seen, documented or can provide photographic evidence demonstrating significant wear of a synthetic (EPDM) rubber mat under the abrasive effects of a slurry. I don't have personal experience running a slurry continuously over a rubber mat so I do not know whether such significantly abrasive conditions exist or not. The problem I have accepting your statement on face value is the fact that I have seen automobile and truck tires run for thousands of miles at very high speeds and pressure with very little wear.

When a slurry of sand, gravel and rock are suspended in water and run over a rubber mat there is almost no weight pushing these abrasives particles into the rubber (they are in a liquid suspension). Contrast the relatively mild slurry conditions with a pressure of two or three ton vehicle bearing down over an area of just a few square inches (in the case of an automobile tire).

Please tell me more about the abrasive wear of rubber mats that you may have seen or heard about.

Thanks!

dragline


  
trnelson
05:46:56 Fri
Mar 23 2012

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Re: Saw-Tooth Mat

Everything wears out with enough use. You should give more thought to how fast rubber wears out. Look at the soles of your shoes. My daily shoes usually only last about a year and I'm not dragging my feet to do that.

Here is a picture of some punch plate made from UHMW plastic used in a sluice at our mine. Note the U-shaped wear on the left edge, it is paper thin there. We have a solid 4' x 8' sheet of it in our feed hopper and it will need to be replaced after 2 seasons of use. That stuff is over 600 dollars a sheet.


Here is a picture of the rubber mat in my test sluice. I have ran so much yardage through it that the ribs are showing visible wear.

  
dragline
14:46:13 Fri
Mar 23 2012

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Re: Saw-Tooth Mat

TRNelson,

Awesome photos TR, thanks. Wear from constant slurry abrasion is a big concern for commercial mining operations and the selection of materials based upon their durability and wear resistance is essential, I understand that. I've read that UHMW can be from between 4 and 7 times more wear resistant to slurry abrasion than mild steel. Has this been your experience?

What materials, in your opinion, are the most wear resistant and yet both economical and practical for sluice construction? I've thought about the possibility of utilizing some harder steels like T1 but such materials would increase the cost of construction immensely.

Is that a 1/2 inch sheet of UHMW, and can you estimate the yardage you would be moving over that after two seasons? Can you also let me know what your screen or classification size is for your slurry on the UHMW and test sluice?

Thanks again,

dragline

  
dragline
19:17:36 Fri
Mar 23 2012

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Re: Saw-Tooth Mat

From the table below I'm guessing that Thermoplastic Urethane would be the ideal material for my saw-tooth surfaced mat project. If the numbers can be believed Thermoplastic Urethane would suffer from 45 to 365 times less abrasion than a natural rubber mat.
          

But these particular data came from an older (1979) Handbook of Thermoplastic Elastomers and UHMW may not have been in common use back then.

Given the right material specification and adequate slurry classification my saw-tooth mat concept might be sufficiently durable for a few seasons of commercial use.

The two tables below are of interest where specifying a rubber type compound. When minimum orders of custom run mats are specified in metric tons of raw materials there is a requirement for balancing the cost versus performance characteristics of various polymers.

          


dragline

  
trnelson
07:42:12 Sat
Mar 24 2012

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Re: Saw-Tooth Mat

Wowzers Dragline, where do I start?

"I've read that UHMW can be from between 4 and 7 times more wear resistant to slurry abrasion than mild steel. Has this been your experience?"

We utilize the UHMW plastic for its slippery properties much more than its durability. It helps material shed into the feed hopper without sticking quite as bad as it would otherwise. Anywhere in the hopper that does not have UHMW plastic, the dirt tends to stick like peanut butter. As for wear the UHMW will wear through faster than 1/2" steel. However, the replacement of the steel is far more difficult than throwing another sheet of plastic in there. Its more like a disposable liner in our application.

"What materials, in your opinion, are the most wear resistant and yet both economical and practical for sluice construction? I've thought about the possibility of utilizing some harder steels like T1 but such materials would increase the cost of construction immensely."

I have never seen a commercial plant built of anything but regular steel. Cheaper the better. Everything in a mining operation is constantly getting welded on and a sluice is no exception. If you go through some ruins of old mines you will see generations of sluice boxes amongst the tailings. They are covered in patch jobs like a favorite pair of jeans. It is not more economical to make jeans out of Kevlar rather than just keep patching what you got. More importantly than that: a sluice box does not usually wear out from abrasion. The death of a good sluice is usually the result of moving it up and down the creek or physical contact with heavy machinery.

"Is that a 1/2 inch sheet of UHMW, and can you estimate the yardage you would be moving over that after two seasons? Can you also let me know what your screen or classification size is for your slurry on the UHMW and test sluice?"

Yes, it is 4' by 8' by 0.5" UHMW bought from Alaska Rubber & Rigging. We run about 60 to 90 yards per hour. In 2011 we sluiced 170 hours. The previous year we sluiced about half that. So 170*1.5*75 (average yards per hour) gives us just over 19,000 yards. The UHMW is not totally worn out but it is showing thin in the middle. I do not have any recent photos to illustrate this but here are some from when we started where the plastic was new.

The material going onto the UHMW is not classified yet.








As for the screen size on the test trommel, it started out with long slots but I realized they let long rocks into the sluice, choking it up and killing production.





So I torched it out and put in 1/4" screen cloth (steel). No nuggets where I dig so I'm basically sluicing nothing larger than pea gravel. Let the trommel handle the bulk of the material!

  
dragline
17:58:27 Sat
Mar 24 2012

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Re: Saw-Tooth Mat

TR,

Your last post really explains a lot. For your reference, the cheapest I could find a 4' x 8' by 1/2" thick sheet of UHMW was in California at a cost of a is from about $413.30 here...
http://www.professionalplastics.com/UHMWSHEETRODTUBE

...so I guess that $600 is a pretty fair price for Alaska. I have noticed that the price of both UHMW (ultra high molecular weight polyethylene) and TPU (thermoplastic polyurethane) have increased 30% to 50% since last summer.

Given that your UHMW 4x8 sheet is taking the full impact of your unclassified ore I'm not surprised that you can go through a sheet in just two seasons.

The application I am contemplating for my saw-tooth mat design does not involve the high impact stress or massively heavy abrasive forces with which you subject your UHMW and corrugated rubber matting. My application need only deal with 1/4 inch classified or smaller ore moving at a velocity of between 2 to 4 inches per second (that's less than 1/4 mile per hour).

Thanks to your help I'm concluding now that I can easily test various materials under the specific slurry loads and stresses demanded by my application but without having to actually fabricate a saw-tooth mat. Any corrugated rubber runner mat from various rubber like or vinyl polymers and with approximately the same pattern dimensions will suffice for my wear analysis experiments. The specific corrugation pattern won't need to be saw-toothed to experimentally determine the ware over time for a given slurry classification size and velocity. I can potentially test any number of different materials by placing each sample in series on the same experimental apparatus.

The experimental problem I have not figured out yet involves the fact that I cannot use the experimentally standardized Tabor abrasion test method because of the reliance of that method on analytically determining abrasion from the material weight loss in milligrams. That objective method probably won't work well because of the potential for increasing sample mass owing to the water swelling factor for these various polymers. Perhaps the microscopic examination and measurement of the visible ware of the exposed right angle corrugation edges will work for my purposes (non-standardized methods are usually less desirable than standardized methods).

My strategy here involves thoroughly testing and validating the abrasion resistance of the various materials that might be practical for my saw-tooth matting application. The goal will be to qualify the lowest cost material that exhibits sufficiently high performance under the demands of the predicted physical conditions.

As you have probably guessed already, my specific application for this saw-tooth matting is completely novel and proprietary. Until I have confirmation that my saw-tooth mat functions mechanically as intended and until I have a patent application submitted and accepted by the USPO I apologize that I will have to leave this specific cat in the bag.

Thanks,

dragline

  
jcazgoldchaser
00:49:41 Fri
Apr 13 2012

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5 posts
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Re: Saw-Tooth Mat

Smooth-on

Smooth on video area


Mold Making for Wood Carvings


So create the sample, make a flexible, removable mold, then cast it in any of the test materials.

  

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