A paper presented at the International Comminution and Classification Congress 2015 (ICCC 2015) held in San Luis Potosi, Mexico, in August, titled Breaking down comminution barriers – new dimensions of particle size reduction and liberation by VeRo Liberator, describes the technology employed by a new type of impact crusher that is claimed to offer dramatic improvements in particle size reduction ratios along with lower energy requirements. The paper, authored by Gregor Borg, O. Scharfe and A. Kamradt, calls attention to the well-known fact that “…the comminution of commodity particles such as mineral ores by crushing, grinding, and milling makes up the biggest single cost factor in mineral processing,” and goes on to explain that a German engineering company has invented and produced an innovative high-velocity impact crusher, the VeRo Liberator, featuring improved particle size reduction ratios and high levels of particle liberation together with low energy consumption and operational noise. It operates without using any water.
In its initial configuration, the VeRo Liberator is fed by a conveyor belt carrying material up to 120-mm fragment size. Unit throughput is about 100 mt/h.
The VeRo Liberator is currently designed for a throughput of approximately 100 metric tons per hour (mt/h) and has been tested on a number of different typical bulk ore and slag samples from mines and smelters around the world, including massive sulphide ore from the Iberian Pyrite Belt in Spain. The ore and rare gangue minerals have been reduced in size by a reduction ratio of 480 and have been liberated to a high degree.
According to the authors, these results are due to the unique working principle of the VeRo Liberator, which is based on high-frequency, high-velocity and, therefore, high-kinetic-energy impacts inflicted on the material by hammer tools. The hammer tools are mounted on three separate levels of a vertical axle-in-axle system and rotate at variably high speeds clockwise and counter-clockwise against each other. The material and particle stream within the machine is highly turbulent and each particle is struck with high-impact forces several times at a high frequency. These high-frequency and high-velocity impacts occur so fast that stress builds up along the particle boundaries due to differential mechanical behavior of the inhomogeneous materials.
Eventually this results in fracture formation along particle boundaries. This concept allows significantly more efficient comminution of ores and recycled materials at far lower energy costs and with far higher degrees of particle liberation. Due to its enormous reduction ratio, the VeRo Liberator can also replace two to three traditional crushing and milling stages, saving substantially both in capex and opex.
The machine is fed via an input funnel and a conveyor belt with feed size up to 120 mm. Maintenance is apparently quite easy. The main shell can be lifted quickly to replace the impact tools. The entire axle-in-axle system with all of the hammer tools attached can be pulled out of the machine and can be replaced by a standby unit in one piece. If, theoretically, a user has to exchange all the impact tools, it would take less than two hours. The configuration (number, size, weight and design) of the tools and the speed of the various tool levels can be modified separately. The VeRo Liberator can therefore be quickly adapted to various input materials.
PMS Hamburg, the company behind development of the VeRo Liberator, is an engineering startup managed by the two sons of inventor Peter Michael Scharfe.
