Size Reduction and Screening Essay Example for Free

Size Reduction and Screening Essay Size reduction and screening The purpose of this experiment was to determine the affect of vibration rate and time on the size reduction and size separation of particles. The objective was successfully completed and the initial sample of soil was separated by vibration into finer particles with a large amount passing through the smallest diameter screen which was 0. 0278 inches producing a final product of fine soil particles which are now easier to transport and store. As can be seen from the graph below (figure 1) undersize particles verses screens, all three different vibration settings (45%, 65%, 85%) produced similar results for the screening process. At the beginning of the experiment (time zero) all of the soil sample was placed on the first screen, number 5, and after repeated screening (vibrating) the sample was broken down in more uniform sizes leaving larger pieces of soil left on the screen while smaller sizes fell through finally producing a fine powder left in the bottom pan. As can be seen from the graph below, after six minutes (the fourth bullet point on graph each bullet point represents two minutes of vibrating) the soil had mostly been sorted into its final sizes. This occurred for all three different vibration settings indicating that after a certain time period, six minutes for this particular experiment, the screening process is 90% complete and may be more cost effective to stop the process as only a small percentage is then sorted into smaller sizes. It can be seen though, that after a few minutes of screening, the original soil sample was sorted into a much more manageable sample making storage and transportation much easier. With regards to retained soil over time, again all three percentage settings produced similar results. The pan weight increased over time as more soil was broken down and this was to be expected as this is the purpose of this particular procedure. Screen 5 and 12, with the larger diameter holes contained the larger, unbreakable soil samples slowly decreased in soil being retained until only the large unbreakable matter was left. All the screens, screen number 14, 16, 20 and 25 kept a rough constant weight indicating that a certain percentage could be broken down and pass through the screens while the rest had reached its optimum broken down size. The higher vibration setting, 65% and 85% had more constant weight and this was due to the sample being vibrated at a higher setting and being broken quicker and thus settling. To conclude, from this small scale experiment alone it can be seen that size reduction and screening is a very useful and effective procedure in reducing the size of a sample making transportation cheaper and easier and taking up less storage space and in a world of cutting costs, this procedure has become vital to a number of different industries