The screen is inclined. A 9/16" screen will get you close to half inch as everything is falling at an angle. You get the odd oversize but for our purposes it works great. It works better than putting 1/2" in the bottom as that seems to treat a lot of 1/2" pieces as oversize. The top two decks spit out the oversize which is recirculated back to the crusher. This was just an example of one type of product we've made in the past and it does work with a finished product production of about 100t/hr. What I am trying to figure out is if there are tricks out there for deciding what screen sizes should be put in all three decks to maximize screen potential. For example, if the goal was to make 3/4" minus gravel with a 2" feed to the screen, what would be the optimal screen sizes to use (ie) I dont think you would put a 2" screen on top because nothing would make it past the first 3 feet of the screen. Or, based on looking at grandpa's comment would it be better to try and close off the impactor somewhat to get the in feed smaller (like 1.5"). I would rather leave the impactor open and try and better utilize the screen but I'm open to trying things.
Thanks for the responses so far.
Luckyj,, lol, I don't know if you'd call them trick's or not. I would prefer to call it knowledge. I would never profess to tell you how to "set up" your screen for better production. Screen's are each different, that said let me explain. You can have two basically identical screen's side by side and each may act different.
First lets discuss the set up of the basic screen with some questions. 1. is your plant level form side to side? A level will work, but observation is still the best tool. What I mean by that is , actually go up watch the material meet and flow down the screen deck. Ask your self, is it in the middle of the screen, is it flowing out to the side so i am using the full width of my screen media? Is there pegging or plugging of the media happening? Is the screen vibration enough to get the fines off the coarse.? 2. is the plant set up right lengthwise? What I mean here is by the time the material get's to the output end of screen box are there many fine's left on that particular deck that should have passed through that screen?
These are just two of a plethera of question's you need to know when your optimum goal is "production".
As far as the optimum setting on your impactor, I run a primary jaw and my secondary crusher is a cone, so I have nothing to offer in the quirk's of impactor. lol. But in my system, the amount of recycle material returning to the crusher for another reduction pass is very important. I try to keep the amout of recycle as low as I possibly can.. every time those rock's go round and round, it all takes up space on your screen. If you can get it crushed as soon as possible and through the screen and out of the plant is optimum.
I hope this helped a little,,, there's is much much more to the science of screening. And I profess to be just a novice in the art.....lol....Gramp.
