Effect on comminution properties of blast preconditioned magnetic mortar

Two Optimized Comminution Sequence tests have been carried to evaluate the effect of preconditioning induced by bench blasting in two different types of mortar, in a comminution process. The materials were collected from 15 small scale bench blasting tests on originally virgin material. All of them had 3 successively shot rows of 7 holes each and were of dimensions 660×280×210 mm with burden and spacing B×S = 70×95 mm. These tests allow comparing the specific surface created by the applied specific energy consumption required to crush and grind the 25-40 mm fractions of the blast fragmented mortar down to 1 mm size. The results obtained showed a reduction of about 11% and 15% for batch 2013 and batch 2014 respectively in specific energy consumption due to the blast preconditioning of the third row burden relative to the blasted burden of the first row.