Fine Particle Software - Experts in Particle Technology - Classification of Particulate Materials

Classification of Particulate Materials

This is a program designed to illustrate how sedimenting centrifuges, hydrocyclones, settling tanks, gas cyclones or air (or liquid) classifiers cut the feed particulate materials into the coarse product and the fine product. The feed particle size distribution is assumed to follow the log-normal law which requires only two parameters: the median size and the geometric standard deviation. The grade efficiency curve of the classifier is also assumed to be log-normal (reduced for wet separators to account for flow-splitting). The user is asked to enter the geometric standard deviation of the REDUCED grade efficiency curve for the classifier, the cut size x50 of the ACTUAL grade efficiency and the underflow by-pass Rf.

Classification assumptions

The user enters the five input numbers and then the total efficiency, the reduced total efficiency and the reduced cut size are calculated and displayed; followed by a series of graphics screens, plotting first the reduced and actual grade efficiency curves (with the cut size marked). Then the differential size distribution curve of the feed and weighted size distributions of the two products are plotted on the same graph with the cut size again clearly shown. There is an option to plot the coarse product or the fine product separately if required. Another option allows "on-screen" change of the cut size and subsequent re-calculation of the total efficiency and the product size distributions.

Task screen

The continuation of the main line of the program leads to the plots of the cumulative size distributions of the feed and of the two products, with another print option of a tabular representation of these, again either on screen or on paper. All graphical displays allow the user to return if a change in the data input is required. There are other options and displays besides the main ones described above including a Print option which allows either a display of tabulated data in a fixed number of steps over the range of particle size, or a paper print of the same but with a user-defined step in particle size. The program computes 100 points in fixed range related to the mode of the feed size distribution. The program also provides for quick switching from the coarse product to the fine product displays or from new to old after an on-screen change in x50.