The spinning disc distributor - Part 2

Abstract

Project Report P/8 issued in February 1972 described the spinning disc rig and the first series of tests, and explained why a triangular shaped spreading pattern is preferable for applying superphosphate to pasture. The 30 in. diameter flat disc used in the tests was fitted with six vanes, stood 17 in. above the ground, and was rotated at 675 rpm. The effect of varying the point of feed of the fertiliser onto the disc was shown and this emphasised the importance of the correct choice of feed point. Tests were then carried out with three different types of superphosphate, one fine, one coarse, and the third consisting of a range of sizes from powder up to granules about 5 mm across the best spreading performance was obtained with the superphosphate containing a range of particle sizes. Finally it was shown that a better spreading pattern was obtained if the vanes did not extend to the centre of the disc but allowed a clear, central space on which to drop the fertiliser. All the work described in the previous report and the present report has been done with superphosphate and the results will not necessarily be applicable to other materials.