Particle size distribution and hopper flow rates



The rate of flow of varying ratios of four sieve size fractions of rock salt through the hopper of a rotary press was represented by a second degree polynomial equation. This fitted polynomial accounted for 90 per cent of the variation in the mean flow rates. No correlation was found between the tangent of the angle of repose and flow rate. High positive correlation was found between flow rate and bulk density, while high negative correlation between flow rate and porosity was observed. There was no significant increase or decrease in flow rates with regard to the quantity of rock salt remaining in the hopper.