METHOD OF CLASSIFYING POWDER, CLASSIFIED PARTICLE AND THEIR USE

PROBLEM TO BE SOLVED: To provide a method for obtaining particles having a uniform diameter, by which the end point of the classification is exactly decided in the classifying method based on a wet method using an electro-formed (plating) screen, and to provide classified particles and a use of the classified particles. SOLUTION: The method for classifying a powdery raw material into the particles, each having a diameter within the desired particle size range, comprises passing a dispersed body, in which the powdery raw material is dispersed in a liquid medium, through a classifying device equipped with the electro-formed screen. The classifying method for classifying the powdery raw material includes the following processes; (1) a process for measuring the turbidity of the dispersed body, (2) a process for judging that the classification should be finished or continued by applying the result measured at the process (1) to the relational formula which has been previously set and by which the end point of the classification can be detected from the turbidity of the dispersed body, (3) a process for repeating the processes (1) and (2) above when the result of the judgment at the process (2) shows that the classification should be continued, and (4) a process for finishing the classification when the result of the judgment at the process (2) shows that the classification should be finished.