5-1. Suppose that a proposal is made to hand-sort all of the refuse from a town of 100,000 people. Estimate the personnel and cost required, and describe the problems involved in implementing such a program. 5-2. Estimate the critical speed and horsepower requirements for a trommel screen, 3 m in diameter, processing refuse so as to run 25% full. 5-3. If the angle of a trommel screen were increased (steeper), how would this affect the critical speed, horsepower, and efficiency? 5-4. Aluminum chips of uniform diameter 1.0 in. are to be separated from glass of 100% less than 0.5 in. by use of a single-deck reciprocating screen. The total feed rate is 1 ton/h, consisting of 0.1 ton/h of aluminum and 0.9 ton/h of glass. It is required to produce an aluminum fraction that is 99% pure (by weight). Find the area and size of screen required. 5-5. Using the aluminum/glass mixture specified in Problem 5-4, assume that the smallest glass particle of signifi- cance is 0.05 in. in diameter. Estimate the air-classifier size and throat veloc- ity required to separate the glass from the aluminum. 5-6. If the pressure drop through a cyclone is assumed to be 1 in. of water, estimate the diameter of cyclone required for various air-flow rates to remove 1 in. diameter aluminum chips. 5-7. Estimate the air velocity required in an air classifier to suspend a piece of glass of 0.5 in. in diameter. Suppose that a 0.4 volume fraction of the throat section were occupied by glass. What would the required air velocity be to suspend this glass? 5-8. What density of fluids is needed to separate glass, aluminum, and plastics into the three individual components? What specific fluids might be used for this purpose? 5-9. Two air-classifier manufacturers report the performance given in Table P5-9 for their units.