Re: Troubleshooting
George,
Is there something that I am missing here?
They have a 3/4 screen on the top deck with a 100% passing 7/8 spec? Why would they not configure 1.25" on the top and 7/8 on the bottom?
Also you didn't mention the depth of material on the bottom deck. What you say in theory is very true, however, with the proper feed rate on a 20 degree incline the opening of 7/8 would seem to be a good choice. ■
Answer To Krusher
Hi Krusher: Do you have a first name?
Your point is well taken and valid. The bed depth is actually a bone of contention here also. For 3/4" - the max bed depth of 4 times the opg at the discharge end of the screen is infact being exceeded (5" deep by actual measurement). This due to high percentage of NEAR SIZE evident in the feed and recirculated load being dropped onto the feed belt to this screen from an impact crusher circuit.
Of course, if the bed depth is too heavy as you are aware, the stroke can not LIFT the coarse particles up thru the thickness and makes carryover of minus 3/4 more of a problem.
By putting in the larger opg we reduced
bed depth and carryover problems.
Keep Smiling........George ■
Re: Troubleshooting
George,
Please keep in mind that I am not being argumenative, but wouldn't the correct solution be to adjust the feed rate? Also would you not stand the chance of getting oversize if the feed rate was reduced? I would be afraid of creating another problem by going to an oversize opening.
I think on an incline of more than 30 degrees a larger opening would have a better chance of working.
Best, Roger Young ■
This Is A Great Discussion....
Hello Roger:
We are not arguing, we are discussing our respective theories and we want people to THINK.
We in fact did, reduce feed rate but, to no avail. We actually diverted recirculating load from another screen off this deck.
So, this did nil to help in reality.
We did prove, by testing one section of a slightly larger opening that it did in fact help decrease bed depth, increase efficiency and did not put the product OUT OF SPEC in reality.
30 degrees here, would increase the FTPM (foot travel per minute)by way too much. It would decrease the bed depth yes but, would definitely speed up the travel rate to a point that the screening efficiency would not be at 95% as outlined by VSMA rules.
Note: if I am scalping a small percent of stones from a large percent of sand......ie a sand scalper (many brands out there). 30 degree or even steeper would work. At this point I AM NOT screening or using screen SIZING efficiency tables....I am scalping and the efficiency rate drops to something in the range of 80 percent efficient.
I appreciate your imput very much.
George ■
Re: Troubleshooting
George,
I understand that, on an incline screen, the rock sees a smaller opening if dropped vertically. However, once the material forms a bed, and is running parallel to the screen deck does it not see the actual opening?
Best, Roger ■
Roger....
No it does not.
George ■
Re: Troubleshooting
Hi, Georgre.
Insuffucuent throughput of a vibrating screen is one of many unavoidable deficiencies of all screeners. The core problem is that they all single-frequency past-resonance linear vibratory systems with low accelerations (4-5 g), weak or no impulse, low amplitudes etc., etc. Absence of principal difference between any traditional industrial screener and a hand sifter causes problems. Hence, insuficienct throughput, blinding, low effieincy...
Using the Ultimate Screener(TM), the only multi-frequency resonance non-linear vibratory system allows for results unseen before. No wonder with acceleration of 800-1000 g, very strong impulses, dynamic boosting, multi-frequency character of excitation etc. Principal differences in vibratory technology cause principal difference in screening/separation/dewatering results. One very obvious result - no blinding of screens (self-cleaning effect).
With a multi-frequency machine all problems described in your letter would have been non-existent.
Thnak you.
Gregory Feldman ■
Re: Troubleshooting
Hi, George.
Insufficient throughput of a vibrating screen is one of many unavoidable deficiencies of all screeners. The core problem is that they all single-frequency past-resonance linear vibratory systems with low accelerations (4-5 g), weak or no impulse, low amplitudes etc., etc. Absence of principal difference between any traditional industrial screener and a hand sifter causes problems. Hence, insufficient throughput, blinding, low efficiency...
Using the Ultimate Screener(TM), the only multi-frequency resonance non-linear vibratory system allows for results unseen before. No wonder with acceleration of 800-1000 g, very strong impulses, dynamic boosting, multi-frequency character of excitation etc. Principal differences in vibratory technology cause principal difference in screening/separation/dewatering results. One very obvious result - no blinding of screens (self-cleaning effect).
With a multi-frequency machine all problems described in your letter would have been non-existent.
Thank you.
Gregory Feldman ■
Hi Gregory.......
Very Interesting reading: When you say ALL problems discussed would be NON existent. I have a problem with this statement.
It sounds very BLACK and white. Definitive.
Of course, screening and screening efficiency is anything but black and white due to constant variable factors of many different influences.
I also sell what is called a NON-blinding screener. The body actually runs at an accelerating force of 2 G's but, the deck itself runs independantly at 50 YES FIFTY...G'S and it is sold as NON BLINDING. Guess what..........I have done many demos in the field with a portable unit and it is non blinding. EXCEPT, at the times that it actually does blind.......oops. It is non blinding compared to most circle throw inclined applications but, it is not the panacea of screenig....it in fact does blind under certain conditons also.
Most typical inclined screeners run at 3.5 to 3.8 G's in actual fact and if it is a horizontal screen which is all driven by motor vs with the help of gravity......these units typically run at 5-6 G's .
I am very interested in further discussing your ULTIMATE screener technology. If you could send me by mail, catalogues for my review, i would be much appreciative.
BEST REGARDS,
George Baker - MODERATOR ■
Re: Troubleshooting
Hi, George
Thanks for your reply. Now I see that you're our biggest (and the only) competitor, because you've expressed very clearly and unequivocally what others often think - they simply don't believe. This is the competition of the multi-frequency technology - people's mind. So thank you for your reply (no irony, thank you sincerely).
I know that processing is not black and white. I also know that single-frequency processing is exactly black-and-white, if we compare it with TV standards, and multi-frequency is color.
Acceleration is a very important thing indeed, and 50 g acceleration of your screener is a great achievement. However, (i) I know about traditional screeners having close to 200 g accelerations and (ii) the Ultimate Screener(TM) has not 50 g and not even 200 g, but 1000 g and over. Still, this is not a key moment. The principal thing is, as I wrote, that any traditional screener, including yours (sorry!) is a single-frequency past-resonance linear vibratory system. "Linear" here means not a shape of a machine's body, which can be rectangular or circular, even triangular, if one wants such a machine, shape won't change anything principally, but the character of vibration, it means linear dependence of parameters, which results in sinusoidal graph on an oscillograph screen. Only the Ultimate Screener(TM) is the multi-frequency resonance non-linear vibratory system. When a million particles of a material are on a surface of a screen of any traditional screener, they all are subject of one frequency. When the same number of particles are on a surface of the screen of the Ultimate Screener(TM) , each particles gets its own unique resonance frequency, follows its own pattern, undersize particles easily penetrate between oversize particles and thus efficiency is very high, as everything, which should have gone through a mesh has a chance doing so. Because of the same reason a very thick vibro-fluidized layer is created, 300 - 500 mm thick, which determines high feed capacity. Agglomerates break, because the energy, with which particles, which are parts an agglomerate consist of, streamline away from each other, each following its unique pattern, is greater than forces of their mutual attraction. Sticky materials and those consisting of irregularly shaped particles do not blind screens, because of the same. The Ultimate Screener(TM) is not a laboratory or a test machine or a prototype, it is the industrial unit working in many locations around the globe. I can't post customer's names here, as I believe it may be against the rules. Will give 10 examples instead, which are either totally impossible for traditional screeners or results are a way greater, principally greater than that of traditional machines. You, as a professional, will certainly be able to evaluate:
1. Wax powder at 15 microns. Industrial screening of total feed capacity 8 TN/hr.
2. Crushed dolomite, 3% moisture. Separation at 1,2 mm at 10 TN/hr x m2 (traditional screeners start blinding already with 6 mm mesh).
3. Coal slurry, 45 microns. Feed capacity of the Ultimate Slurry Processor(TM) machine of just 2m x 1m - 300 m3/hr. Traditional machines cannot do anything, not even 1 kg/hr below 600 microns.
4. Auriferous ore, 10 mm. Feed capacity 15 TN/hr x m2. Traditional screeners cannot screen below 20 mm.
5. Quartz sand, 200 microns, dry. 6 TN/hr x m2. Traditional screeners - zero.
6. Quarts sand, 1 mm, dry. 30 TN/hr x m2.
7. Gravel, 5 mm. 20 TN/hr x m2.
8. Coffee sludge. 20 microns. Replacement of a centrifuge due to much greater efficiency, dewatering grade and greater cost efficiency.
9. Tungsten Carbide. Class 1. 63 microns. 3 TN/hr x m2 (traditional screener no more than 30 kg/hr x m2).
10. Chemical product, bromine derivative. 63 microns. All particles are below 200 microns, but blind immediately even 800 mm screen of any traditional screener. The Ultimate Screener(TM) processes at 63 microns with the rate of 2 TN/hr x m2.
I'm e-mailing to you the detailed Guide about the Ultimate Screener(TM) and other multi-frequency apparatuses (Ultimate Slurry Processor(TM), Ultimate Dewaterer(TM), Ultimate Filter(TM), Ultimate Delumper(TM), Laboratory Ultimate Screener(TM), Ultimate Crusher(TM)).
Thank you.
Best regards,
Gregory Feldman ■
Very Informative Answer........Thankyou
Gregory: Your answer was perfect. I am excitingly waiting to see the catalogue information you are forwarding me. The detailed feld knowledge that you have shared is quite astonishing.
If your information is true.....and I have no reason to believe otherwise after your detailed expert explanation, then I have had a very beneficial day. I have learned something new and of great interest to me.
I will be definitely interested to do a demo on some tough material and watch the results as the material is actually processed to be properly convinced.
Thankyou very much for your imput, much appreciated.
Respectfully, George Baker - Moderator ■
Troubleshooting
VIBRATING screen is not passing enough fine material. WHY?
I had this one again, in the field this week. It was a 7x20 double deck vibrating screen. CIRCLE THROW, TWO BEARING DESIGN, inclined screen at 20 deg standard downhill slope.
CUSTOMER COMPLAINT: Not handling the tonnage, TOP DECK carrying fines over that should have went through the 3/4" opening. Wanted to make 100% passing 7/8" spec.
TROUBLESHOOTED & solution: We do process of elimination. We confirm what is right and then decide what is wrong.
STROKE CHECK DONE: It actually showed as 3/8" size circle. THIS was acceptable by the VSMA rules or guidelines. The speed I tached out at 851RPM.....perfect correlating RPM to stroke as per VSMA and experience. I used a protracter gauge and the angle was 20 degrees.....also a perfect match for speed/stroke/slope charts of VSMA. Ummmmmmmmmm........NOW WHAT?
The wirecloth was cross verified at 3/4" clear opening with mid range wire diameter .192 range nice and tightly installed.
We went to the stockpile and measured the biggest piece of stone in the stockpile. Basically, all the stones measured would be approx. 1/2" minus by tape measure. HOW COULD THIS BE??? The spec calls for 100% passing 3/4" -- the cloth opening was 3/4" so what was the problem here???
FORESHORTENING OF THE OPENING WAS THE PROBLEM. At 20 degree installation angle the material sees a shorter opening than the one installed in the deck. So, it was seeing with a 3/4" clear opg at 20 degrees.......nominal 5/8"-1/2" range give or take.
SOLUTION: We installed all 15/16" clear openings down the full deck and the remeasurement in the stockpile was basically 100% minus 3/4" clear. The material does not see the nominally bigger opening. The steeper the angle of slope the more this applies.
ON A FLAT OR HORIZONTAL SCREEN: The material sees the full opening at zero degree flat installation angle. So the above concept does not cross apply.
HAPPY SCREENING out there folks !!!!
GEORGE BAKER, MODERATOR ■