Abstract: Disclosed is a sand classification plant dynamically controlled to divide feed material from a primary and a secondary source among several stations by particle-size and to blend the station contents in selected ratios to produce one or more controlled products having respective particle-size distributions and one or more uncontrolled distribution by-products. The invention includes automated features such as regulating the ratio between two or more controlled products to optimize the use of feed material, regulating source material feed and water flow rates to optimize production, combining two or more stations to make up for the missing output of an empty one, and controlling the flow rates from the individual stations in accordance with changes in feed particle-size distribution and in particle-size distribution of the output from each individual station.