Abstract: Apparatus for controlling the operation of a grinding system having a plurality of mills running in a parallel fashion, in which the operating condition of each mill is controlled such that a predetermined physical quantity, which changes dependent on the running condition, is equal to set values for the mills, and the set value for each mill is variably controlled so as to maximize the amount of pulverized material. The apparatus includes means for comparing a pulverizing amount F.sub.A per unit time of the mill under control with that F.sub.B of another mill, and controlling the set value for the mill under control so that a difference between the pulverizing amounts (F.sub.A -F.sub.B) is maximized while the set value for the other mill is fixed, whereby the set value of the mill under control is automatically optimized.

Abstract: A vertical mill for material such as cement raw materials, clinker, coal, or the like comprises a grinder portion which has rollers arranged to grind the material by their rolling on a rotary table, a separator means which is positioned above the grinder portion and which classifies the ground material conveyed pneumatically from the grinder portion to the separator means by the two opposite forces of centrifugal force of a rotary disk and of fluid resistance of a vortex flow, a plurality of straightening vanes which are mounted between the casing and the inner cone and which adequately regulate the direction of the fluid in the lower portion and in the upper portion in passage between the grinding portion and the separator means, and a casing outside the separator means having the appropriate shape for forming a horizontal vortex flow in the separator means. The aforesaid vertical mill structure improves the classifying efficiency of the separator means.

Abstract: An air classifier comprises a casing formed of a generally hollow cylindrical vertical casing body and an inverted conical hopper fixed to the lower wall of the casing body. A fine product outlet duct is provided at the center of the upper wall of the casing body. An air-powdered material inlet duct and a secondary air inlet duct are set in the diametrically opposite positions of the vertical wall of the casing body to project tangentially outward. A vertical rotary shaft extends through the central portion of the casing body. A rotary disc member for concurrently carrying out the dispersion and classification of a powder raw material is fitted to the lower end of the rotary shaft at a boundary between the casing body and hopper. A cage-shaped assembly of guide vanes is provided in the casing body to conduct a mixture of air and powdered material into the casing body.