Spherical particles of an ore of size R = 2 mm are roasted isothermally in a constant environment in air stream. The following data is obtained: 1, min XB 15 0.334 30 0.584 60 0.88 Assume that the reaction follows the Shrinking Core Model. a) Find the rate controlling mechanism b) Determine the time needed for complete conversion of the spherical particles. od consisting of 20 wt% of 1-mm particles, 30 wt% of 2-mm particles and 50 wt% of 4- the reactor the particles