ml samples of the slurry were siphoned into 250 ml mixing cylinders each cylinder received approximately 80 g of ore corresponding to a percent solids of 36 to 38 polymers were added to the cylinders using 5 and 10 ml syringes the cylinders were inverted five times after each polymer addition to ensure proper mixing when peo was added alone to a cylinder the dosage was added in a ratio to simulate the addition of hpc prior to the addition of peo the tests were timed over a period of 30 minutes graphs showing the height of the interface versus time are plotted forty grams of phosphatic clay waste were thoroughly mixed with 200 g of water in a 250 ml mixing cylinder polymer dosages ranging from 0 05 to 0 50 lb ton were tested in tests where a combination of hec and polyacrylamide was added to the clay water slurry the hec was always added first the cylinder was inverted five times after each polymer treatment to evenly distribute the flocculant when polyacrylamide was added alone it was added in the same amount as experiments where the combination was used to simulate the addition of the hec prior to the addition of the polyacrylamide the settling tests were timed over a period of 30 minutes polyvinyl acetate pvac and polyethylene oxide peo have been shown to improve the filtration of leach slurries but the resulting filter cakes were very tight and extremely difficult to wash the hpc peo flocculation allowed removal of the acid product using a series of thickening steps and countercurrent decantation the bonding of the flocks was so strong that the use of screening for solid liquid separation might also be employed the settling rates of leached.