That Is Tough Screening
Anything under 3/8" minus is considered fine screening. Anybody can screen clear aggregate range fairly easy but, the finer the opening the tougher the job.
1. FIRST, sounds like the screener is too small (open area is too small) making the fines carryover. This would mean the BED DEPTH or depth of the material specifically at the discharge end is TOO DEEP.
2. What is make, width, length of this screener?
3. What is the speed of the box (by tachometer?) and what is the size of the circle? and what is the decline or slope of the angle of the screen?
4. Is your slotted wire T304 S/S?
5. Are you wires DRUM HEAD TIGHT across the end to end tension or is it SIDE to SIDE TENSION?
6. Are you spreading the material fully at the feed end of the screen across the FULL WIDTH of the machine?
7. Are you feeding directly ONTO the wirecloth or into a feedbox?
8. Is this straight electric or DIESEL Operated unit?
9. Granite - Have you added any extra LINER PLATE weight?
10. Setup should be 1/4" circle size running at 1200 RPM at a slope of between 20 - 25 degrees to do this CUT.
11. Is this stuff WASHED at any further point or NO? Because you can float that stuff out fairly easy. MAY NOT be an option though. ■
Re: Removing Fines
Fine screening requires tremendously large screening area. Low cost way to remove fines is by using vibratory conveyor: If long enough, crushed rock agregate is segregated, fines on bottom, coarse on top. Wisely designed spout partition/suction can catch most of the fines on the conveyor oulet. ■
Ultimate Screening Solutionosh.
Dear Sir,
We are able to screen fine granite in order to optimize your crushing cycle and reduce dramatically the load on your equipment with the most efficient equipment in the market, using a multi-frrequency vibrating screen.
You can send me an email:
mandil@kroosh.com
and go to our site:
www.kroosh.com
Best Regards, ■
Prescreen Fines Out
you could prescreen fines out prior to this screen but, not really that practical.
ESTETICALLY too coarse is really no problem as long as you LAND in the SIEVE BEND range that says you meet spec.
You could float the fines out using screw or dewatering disc, but probably not practical where you are working.
YOU could adjust your crusher to more coarse setting to relief the amount of fines the screener needs to deal with.
A longer screen box would decrease the BED DEPTH and allow more retention time on the deck to increase your efficiency.
Increase the slope of the screen to decrease the BED DEPTH.
ARE YOU PLUGGED on the WIRECLOTH? What spec on the fine cloth, what alloy? (steel? stainless steel? piano wire? flexmat?)
ARE THEY TIGHT AS HECK? SHOULD BE...drum head tight. Are your rail rubbers all there and in good shape?
ARE you tension rails in good shape? If not your wirecloth will not be tight enough and INEFFICIENT.
are YOU FEEDING properly??? Are you overshooting the feed tray directly onto the WIRECLOTH. Makes the screen shorter and your FINES CARRYOVER more. Are you hitting the screen feed tray but, not SPREADING the material.....sideplate to sideplate? and losing screening efficiency and carrying over fines?
RUNNING by diesel? could be too slow on screen box RPM..which will cause fines carryover. HYDRAULICALLY run screen box, belts and conveyors???? COULD be stealing power from each other and making you INEFFICIENT.
TOO MUCH LOAD.....off the feed conveyor??? How much are you feeding in TPH? What troughing angle degree on the feeding belt to the screen?
Keep Smiling...... "We love screeing" ■
Removing fines
We are screening oversize out of crushed granite and are ending up with too much fine material (no.50 and no.100 out of spec). Is there a way to remove that much fine material? Here is the spec. of the material we are producing:
Sieve %passing Spec.
no. 4 98% 90-100
no. 8 74% 65-95
no. 16 57% 45-70
no. 30 46% 30-50
no. 50 37% 18-36
no. 100 26% 10-24
no. 200 11% 5-15
We are using a a .5" square wire on the top deck, and a 4mm harp on the bottom deck. We could leave more #4 rock in the mix to change to get the no. 50 and 100 in spec, but it leaves us with a product that is aesthetically to coarse (meets spec. though).
We are new to screening, so we don't know all that is available to us, but is there a way to remove material that fine? ■