At the 8 stone stockpile the sample is pulled and taken to the lab where the gradation is tested. Shaking a sample of stone through a series of sieves in a specified amount of time checks the gradation. Figure 1-3 shows a critical sieve value along with upper and lower control limits associated with gradation. The three quality factors are equally important, if one of the three were to become neglected. This would adversely effect the stockpile gradation.
Flipper allows or disallows lower limit material into the mix.
Too much mud in mix can cause the material to be too dirty causing the decant value to be too high.