High-velocity impact breakage is an option to increase comminution efficiency significantly. The widespread application of traditional ball mills and SAG mills in comminution is characterised by robust technique but also by low-velocity surface breakage of the feed material. In this conventional technique the breakage from a single impact is rare and most particle collisions result in partial abrasion only (Morrison and Powell 2006) and in comparatively high energy consumption. In contrast, the VeRo Liberator comminution system shown in Figure 1 operates at high-velocity, with impact speeds of greater than 200 m/s, stemming from high-speed counter-rotating hammer tools. This process moves comminution away from low-energy surface abrasion with minor breakage to more the more efficient impact breakage. The new VeRo Liberator features a vertical, quadruple hollow axle system, carrying special steel hammer tools up to one meter in length on three tool levels. A propeller on the fourth level controls the air flow within the comminution chamber. The high impact speeds are achieved by counter-rotating tool levels, which can each achieve up to 1600 rpm in a clockwise and anti-clockwise fashion, rotating against each other. The feed material, top size 120 mm diameter, passes continuously, vertically (gravitationally) from a feeding funnel at the top through the comminution cylinder, typically taking 20 to 30 seconds. Each particle of the feed material is hit by multiple impacts at a high frequency and at very high velocities during this quick pass through the machine.
CITATION:Borg, G, Scharfe, O, Kamradt, A and Meyer, N, 2019. High-Velocity Impact Breakage for Lower Energy Consumption by VeRo Liberator Technique, in Proceedings MetPlant 2019, pp 389392 (The Australasian Institute of Mining and Metallurgy: Melbourne).