Quantifying variability of ore breakage by impact – Implications for SAG mill performance

摘要

The standard JK drop weight test breaks single particles at five size fractions each at different energy levels by dropping a given weight from a certain height. The progenies of all particles at a given energy level are sieved and the degree of breakage of all those particles at that energy level is presented as t10% (percent passing 1/10thof original size). This method assumes that all of the particles in a single size fraction have the same mass and experience a similar degree of breakage and calculates the average breakage characteristics of an ore domain from impact loading. Hence, this standard approach does not capture the breakage variability that exists among ore particles. To investigate the breakage variability of ore, the drop weight testing method has been extended where the energy applied and the degree of breakage for each particle within the sample are measured separately. Therefore, the degree of breakage for the ore domain is expressed as an envelope of t10% vs energy curves. This approach provides some insight into the intrinsic variability of the response to impact loading within an ore domain. Several rock types were tested by the extended DWT testing approach and the implications of ore breakage variability for a SAG mill treating these materials are simulated for a standard SAB circuit using the JKMRC grinding models.