Pit & Quarry, July 2015

SCREENING Deisters Joe Schlabach discusses the benefits of different screening options and more with Pit Quarry J oe Schlabach vice president of marketing and sales with Deister Machine Co led an educational session on the basics and misconceptions of screening at the 2015 AGG1 Aggregates Academy Expo Schlabach a 36 year Deister veteran who focuses on applications and applying screens in his position says working with equipment firsthand helped him gain expertise on screening and screen media Pit Quarry connected with Schlabach to discuss screening further P Q At AGG1 you said screening combines art and science What do you mean by this Schlabach There is no literary source science that can tell you everything you need to know about how to properly select and operate a vibrating screen There is a great deal of experience art that is a valuable help in selecting and operating vibrating screens Every deposit is unique and may require some special consideration to get the best results This is where experience can be a big help in pointing in the right direction to get the best results Even then the final tweaking often is a matter of trial and error or different tests to see what combination of operating parameters and screening media will produce best results P Q In the beginning of your AGG1 session you reviewed horizontal screens triple deck horizontal screens and inclined screens Between these which would you say is most cost effective When is each screen useful Schlabach The type of screen is dependent on the application That said if any of the three types would work then the inclined screen is the most cost effective for a number of reasons Because it is inclined it uses gravity to convey the material allowing for a circular stroke rather than a linear or elliptical stroke required with the horizontal screens The amount of stroke or amplitude of the stroke is typically less than what is required on the horizontal screens The end result is that the inclined screen operates at a lower g force and requires less horsepower to operate P Q You also mentioned multiple times that no screen operates at 100 percent efficiency as opposed to what a lot of companies advertise If thats the case what is a good efficiency percentage producers can expect to get from their screens Schlabach I believe that if a screen is at 90 percent efficiency or better it is usually very acceptable Maximum efficiency is probably around 95 percent Depending on the application screens can operate at less than 90 percent efficiency but as the efficiency is reduced there is more and more potential for the screen to operate less consistently on a day to day basis In other words as time goes on with more deposit and weather to the screen there is more potential for the screening results to change which could affect the specifications of the material being produced P Q How does an operator determine efficiency of the screen Schlabach Efficiency equals the percentage or tons of undersize that actually pass through the openings on a deck divided by the percentage or tons of undersize in the feed to that deck For example if there is 100 tph in the feed available to pass the openings and 90 tph actually passed BY MEGAN WILKINSON Best Practices Deisters Joe Schlabach 20 PIT QUARRY July 2015 www pitandquarry com