You Screen
If your screen deck is a two or three section top deck there is no reason you can't do it -it is just a matter of trial and error to seehow the flow is after the change. ■
Re: Modification Of Screen
Dear Shri Debashishde,
It seems you want to use the deck’s first part to screen out finer portion of the material, and deck’s second part (near discharge) to screen out coarser portion of material. Will this not demand very length deck? If length is not adequate then how about screening efficiency? The issue relates to screen’s design and functional parameters. I suggest you to contact screen manufacturer.
In effect, you want to achieve double deck function with a single deck, which automatically implies that the single deck area will be twice the area of each deck screen, in double deck screen.
Regards,
Ishwar G Mulani.
Author of Book : Engineering Science and Application Design for Belt Conveyors.
Advisor / Consultant for Bulk Material Handling System & Issues.
Email : parimul@pn2.vsnl.net.in
Tel.: 0091 (0)20 25882916 ■
Re: Modification Of Screen
You sure can divde the length of the screen into 2 sections with 2 different sizes of screen cloths.
The arrangement will definately reduce the screening efficiency. i.e. some of the material that is -10mm will not get a chance to "see" the cloth and will get carried to the next section of the screen. similarly some of the material that is -20mm will not get a chance to "see" the cloth and will get carried to the discharge of the screen.
However, the screening efficiency can be increased by making the material move slower on the screen. This can be achieved by either of the below listed 2 option.
1. Reducing the angle of inclination of the screen.
2. Making the Screen rotate in the counter-flow direction. ■
Modification Of Screen
thank you Sir,I have also planned somewhat in this line. Reducing inclination will increse the retention time but this will probably reduce the carrying capacity of the screen also.Since it is being fed by vib feeder the screen may jam or over flow.so i should increase the frequency of vibration which will increse the capacity and at the same time help in getting the better screening effect.am I in line? I could not get your point about reverse movement.If you could elaborate and express your views on above. ■
Re: Modification Of Screen
The increase in the frequency of vibration will definitely increase the capacity of the screen. But this will be at the cost of lower L10 life of bearings. Moreover, the support structure should be capable to withstand the additional dynamic load.
In case of single shaft screens, the forward movement of material is the combine effect of Screen down slope and forward elliptical stroke generated by the rotation of shaft in the direction of flow of material. Making the shaft to rotate in the counter-flow direction negates some of the effect of forward movement of material because of down slope. The net effect is the material moving at a slower speed. This arrangement is usually adopted for Screens at steep angles. (-22 1/2 deg to –25 deg in case of Coal) ■
Modification of screen
We have coke screen in a mini blast furnace stock house for getting (+) 20mm.The fines (-)20mm get rejected.We want to use the portion 10 to 20mm coke now and then to charge with iron ore and get better coke utilisation. I can not straightway change the screen to 10 mm ,then all coke down to 10mm contonuously mixes with the charge but it chokes the blast furnace.I dont have the space to change to a double deck screen and space layout to accomodate conveyor for carrying out the in between sized load.May I change the screen partially(first portion) to 10mm which gets all the fines and later part of the screen cloth 20mm which will pass through 20mm size out of the remaining charge which has already been screened off for 10mm.means this later part will contain 10 to 20mm particles and shall be carried by the existing conveyor earlier used for fines.The bottom hopper of the screen shall also be proportionally separated to take the materials separately.Probably it is difficult to explain without sketch but if anybody knowledgeable on the issue if understands and express his views, I shall be obliged. ■