GB1166332A - Control of Material-Reduction Operations. - Google Patents

Abstract

1,166,332. Permeability measuring instrument. CEMENTFABRIK HOLDERBANKWILDEGG A.G. Jan.19, 1967 [Jan.19, 1966], No.2974/67. Heading G1S. A regulating device on a grinding apparatus comprises an arrangement for measuring the permeability of the ground product. The device comprises a permeability cell with a cylinder 2 through which measuring gas flows and two gas permeable screen plates 4, 10 for compressing a pellet of test material, the screen plates being movable relative to each other into a filling position and a pressing position in which they are a prescribed distance from one another to form a pellet chamber 20. The lower side of plate 4 is connected by way of pipe 6 to a measuring gas pipe 103 of a quantity meter 199. The screen plate 10 has been moved into the position shown out of the cylinder 2 into bushing 7 and the screen plate 4 is movable to a position to eject the tested pellet. The quantity meter 199 comprises two measuring liquid containers 101, 104 arranged one above the other with the sealed space 102 above the liquid level 112 in container 101 being connected to the pipe 103. The upper liquid container is fixed in space whereas the lower container bears on the weighing pan 109 of a balance and is also open at the top. The two containers are joined by a pipe 111 extending from the bottom of container 101 to below the liquid level in container 104. In operation the material under test is fed into chamber 20 through tube 28, compressed to the desired volume by movement of the plate 10 and then air is fed down tube 28 through the plate 10, the pellet and the plate 4 to the space 102. A quantity of liquid corresponding to the gas quantity flowing through the permeability cell is displaced from the upper container to the lower container which increases the weight of the lower container and hence the movement of the weigh pan is dependent on the quantity of air flowing through the pellet and hence of the permeability thereof. Timing means are provided to measure the time taken for the indicating element to move between two prescribed points. In the embodiment described the indicating element comprises an arcuate strip 115 connected to the pivoting arm of the balance, the strip having a slot 117 through which the light from a source 119 reaches a photo-cell 118 while the strip moves the prescribed distance. The time indication gives the rate of flow of the gas through the pellet and hence the permeability of the pellet. Control means are provided to influence the degree of grinding dependent on the time taken for the weigh-pan to descend.