Originally Posted by POWERPACKED

Dear Gentleman - This is my first thread on these very helpful forums, and hopefully not the last. Need your advice/help.

I have been asked by my employer to shop for new screening equipment in order to reduce the fines content in our product and especially -30 mesh USS, Existing screening equipment reduces the fines content down to 48% of final product which we want to reduce down to 13% with 97% -30 mesh content of the fines.

Our moisture/H2O content varies between 0.4%-0.75%

We sent test samples to couple screening equipment suppliers eg. Rotex/ MidWestern Equipment/Derricks with satisfactory and promising test results.

Our biggest concern is moisture and screen blinding, what are your thoughts? what are your recommendations? we are leaning toward Rotex Mineral Separators which fits the square footage of our Mill which comes with de-blinding balls and we are planning to blow hot air is into the fully enclosed screener.

Please advice, thank you

Regards,

Y@S!

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The deblinding balls love to escape the play pen, and they are expensive to replace too and a Rotex will blind if it is flooded just like any other screen.

Do you have a flight conveyor above the current screens, or are you using a screen train with cascading flow after the crusher out feed with multiple cuts

after the dump pocket?

As everyone is using amfo It will be next to impossible to bring the fines level down unless the tunnel walls and roof are slot cut with the undercutter-assuming you are using a Joy 15 RU with the 15 foot bar/12 foot actual length to reduce the amfo bags used per heading

The only realistic way to eliminate any fines prior to screening is washing the product with salt water which is done with solar salt or the salt lake product coming from chile, peru, Venezuela,

and the Caribbean as well as the solar salt flats in the United States.

Washing halite its not cost effective unless it is allowed to dry; but saying that the solar salt plants use salt water to wash thier product and clean it prior to packaging and stock piling using

yellow prussiate of soda like every one else for anti-caking as the salt they make is more dense than sedimentary Halite.

But the salt water rinse will not disolve the halite like rain water and you would want to do this prior to spraying the no cake solution on the salt to be stock piled or loaded in rail cars.

We sent halite samples to Pennsylvania Crusher Inc. thirty years ago in PA. to run through their lab using a Bradford Breaker and we were given an excellent sample nearly free of shale rock-

and dust but we could not lower a Bradford Breaker underground in one piece and selected a Spokane crusher (following what Canadian salt did at its Pugwash N.S. mine previously.

The Bradford Breaker will size and screen for the desired capacity you have and they have a proven design and have been made for almost 105 years now;

here is their home page www.penncrusher.com nice folks easy to talk to.

lzaharis ■

I know little about screening, but is there any merit in allowing the salt to fall through a rising air stream so that the finest particles are carried away with the air?? ■

Originally Posted by POWERPACKED

href="showthread.php?p=63988#post63988" rel="nofollow">

Thanks or the reply, Many measures has been taken with our crushing and mining methods to reduce fines. BUT still there are still some fines that we need to deal with! Our Mill operation is on surface not UG, so unfortunately we have to deal with moisture issues! We don't dry our salt and we are not planning to do due to cost, so screening efficiency and compaction are sought as an alternative!

My issue is that no one out there in the salt industry is screening -30 mesh salt except UG with dry conditions!

Which makes my investment a leap of faith! what are your thoughts on heated screen decks? similar to what mid western offers?

Any other experiences out there?

No its not a leap of faith at all.

Using a Bradford Breaker and a series of flat screens will give you the cut you will be very happy with.

dont worry about the leap of faith business- a flat screener will give you a better cut period with less work and aggravation and maintenance.

The Derricks we had replaced Busy Bee screeners but they still blinded up from surges of unfinished salt.

I would seriously send a few tons to the various flat screen builders and I know you will be very satisfied with them.

The old International salt mine at Detroit-now Detriot Salt Inc. had flat screens underground for finished salt using hand made wooden frames ( simple and easy to repair as they worked slowly and removed the fines quickly and this removed the minus thirty mesh fines and gave them a great product.

I am unsure if the new owned continued to use the flat screens in the old screen plant or bought new ones.

I have attached a few files for you about the Smico screens and the Pennsylvania Crusher Bradford Breaker.

The Pennsylvania Crusher folks and the Smico folks have complete test labs for product screening so thats not an issue.

To get an accurate scalp and cut you would want to send a large amount of salt to both of them probably forty tons to get an accurate accounting as they both have complete testing facilities.( that way they are not hurried and would not ruin a very small batch of minus six inch run of mine product.

The Bradford Breaker has a lot of positive features as it simply rotates and lifts the product and gravity does all the work with the product being sized and then falling through the screen plates and any rock is ejected out the rear end of the unit continued-

==================================================================================================== ================================

(Thinking out load here you could take a portion of the mines naturally heated exhaust air at the surface landing and pipe it to the outer shell of the Bradford Breaker and keep the finished salt dry until it exits the breaker at the rear along with the exhaust air which would be delivered away from the breaker building or used to heat it in winter-

strictly depending on the exhaust gas content and its testing for NO2, CO, CO2, aldehydes, methane, Radon, etc.)

==================================================================================================== ===================================

continued;

The material falls back on itself and is essentially allowed to be sized by the flow and gravity while scalping at the same time.

The companies brochure explains it all very well.

They have a number of units in salt from what I remember reading and these machines have been in use and built since 1905 when the company was founded.

disclaimer

I have no interest financial or otherwise in General Kinematics, Derrick, Smico, Pennsylvania Crusher.

lzaharis

Attachments

smico1 (PDF)

horizontal (PDF)

bradford_breakers.cfm (PDF)

■

Originally Posted by designer

I know little about screening, but is there any merit in allowing the salt to fall through a rising air stream so that the finest particles are carried away with the air??

It amounts to a pancake flour dust storm of minus 30 mesh airborne dust in practice and its a mess when it comes to passive vacuum systems

meaning it only moves when it wants to and only then unless it is suctioned using a positive displacement blower in Hg service

The added problem of silica dust in the air(silicosis)

roof drilling for roof bolts and face drill cuttings when in rock and salt as well as undercutter use when rock in the floor is encountered and from transfer points and open belts is another huge health issue for miners, screen plant operators and mine owners.

lzaharis ■

Originally Posted by POWERPACKED

Thanks or the reply, Many measures has been taken with our crushing and mining methods to reduce fines. BUT still there are still some fines that we need to deal with! Our Mill operation is on surface not UG, so unfortunately we have to deal with moisture issues! We don't dry our salt and we are not planning to do due to cost, so screening efficiency and compaction are sought as an alternative!

My issue is that no one out there in the salt industry is screening -30 mesh salt except UG with dry conditions!

Which makes my investment a leap of faith! what are your thoughts on heated screen decks? similar to what mid western offers?

Any other experiences out there?

the solar and sea salt plants are screening 30 mesh fines and always have screened for block salt too with 30 mesh or less material ■

The two mines in New York including my former employer are screening that fine and have been for years as they had to eliminate the dust due to complaints from customers etc.

I never saw much point in it as it detracted from bulk tonnage being 20-30 percent annually. They never bother to screen the fines from the bag salt bins which is something they have nver worried about since they switched to anfo from dynamite. ■

Originally Posted by POWERPACKED

lzaharis - Thank you very much, very helpful information, I guess what I meant was no Mine is screening down to 30mesh, in evap and solar plants its usually dried salt vs in our case moisture content of 0.4-0.75% H2O Content, so this is what I am worried about screen blinding

==========================================================

That is the specific reason I mentioned the Bradford Breaker

as it cannot become blinded due to its operating method of

rotate lift and screen and the screenn plates cannot become

blinded as they are constantly rotating in operation always

scalping and emptying with no issues. ■

SOME GENERAL THOUGHTS:

1. the companies you have worked with testing your materials..are good outfits...they all have XL Merits.

2. If they in-house tested, with the same moisture content...as in real life...and gave you the sieve analysis results......then, they have proven that they can or cannot do the job. The likelihood is from many past historical tests and actual applications in the field.....they KNOW that they can or can NOT do it.

3. If they DID NOT TEST with HOT AIR blowing....do not do that...in my opinion.......i see other problems developing from that..with material not staying down on the wirecloth....and theoretically upsetting the natural foot travel of the material as designed over the wirecloth surface.

4. Ball trays are XL...for keeping WIRECLOTH open and clear, very well proven

5. Heated WIRES.....by HANCO HEATER bus bars,,,,,,,,IE like MIDWESTERN might use....have pluses and minuses.....PLUS...heats wire, does not allow buildup theoretically...MINUSES: must keep contact points clean or wire DOES NOT HEAT......= blinds and plugs. OOPS.....

6. ASK to visit a SALT outfit where there are doing it now....and or be at the TEST facility when actually testing.

GOOD LUCK.....George Baker ■

Looking at the first message of the screen, you seem to have talked to us already. I assume it was with my colleagues from our Head Quarters in Cincinnati, Ohio.

I am almost sure that my colleagues gave you references in various applications?

I suggest that you mention your concerns to them and listen what the answer is. I am sure that they are open for witnessed testing or a reference visit. ■

Originally Posted by POWERPACKED

Thank you all for your replys and information, the hot air blower is to keep the screen dry when its shut down "We do hoist inspection so we are down 3 hours/day" and when coming back to operation from the weekend! I want to make sure that I start the screening process with a dry screen and hope that with a thing bed depth 2-3mm and 2" balls 2-3 inch strock and 2G force that would keep the screens clean! I am hoping so other thoughts?

Your hoisting shaft is like ours isnt it with a suspended timber frame and wooden guides?

As I mentioned previously using a bradford breaker you not have to deal with that at all.

The salt will fall away and any salt crust will be broken off by the new salt entering it all the time.

moisture is not an issue with them because of the simplicity in design.

leon ■

Y@S!,

If you are looking for the 30 mesh wire cloth specifically, try this website.

bwirecom

I have used these guys from New Jersey in the past and they are the best. very high quality (they weave their own stuff), fast shipping, and always punctual with my orders.

Their service was also excellent and they even send me some large samples, so that I knew what I was about to order was the right stuff.

Good Luck with your task

-J ■

DERRICK SCREEN in BUFFALO NY..........excellent high speed screeners made specifically for fine cuts and mega history of success in this fine mesh cut range.

They of course run a high speed, with small eccentric and special wire alloys to suit the aspect of dealing with moisture all the time.

Just a thought......... ■