Mechanics of coal spirals

Separation of liberated, organic contaminants from polluted soil has been simulated both numerically and experimentally. Simulation of the motion of the individual particles shows that the organic contaminants accumulate in the middle of the trough while soil particles move to the inner rim. The results suggest that the separation is determined by segregation in the first turn of the spiral. It was found that the separation is optimal when the spiral is operated close to the maximum capacity. Both a high slurry density and slurry flow rate are found to be beneficial.