SEPARATORS IN GRINDING CIRCUITS

Conventional separators in grinding plants for raw meal, coal and cement have often shown rather poor separation performances. The recently developed high-efficiency separators are especially noted for their markedly improved separation performance and sharpness of separation. The mode of operation of a separator may be characterized advantageously by the shape of the Tromp separation curve, which shows the selectivity as a function of the particle grain size. Modern separators are used in grinding plants with ball mills, roller mills and high-pressure grinding rolls. Their substantially improved separation performance, especially with higher product finenesses, leads to a higher output and a lower specific energy consumption. However, the properties of the product are also affected by the separator's mode of operation. Due to the greater sharpness of separation the grain size distribution is narrower and the strengths, especially the 3 to 28 day strengths, of cements with the same specific surface area are therefore higher. On the other hand, the workability of the cement may be impaired.