Mechanics process and acoustic emission characteristics of raw magnetite ore under uniaxial extrusion fragmentation

In order to study on the extrusion fragmentation mechanism of raw magnetite ore,uniaxial extrusion fragmentation experiments were carried out with the use of ATW-3000 Electric Hydraulic Servo Rock Tri-axial Text Machine and PCI-2 Acoustic Emission Test System to analyze mechanics process and acoustic emission characteristics in tests.The results show that deformation in fracture compression phase is 45% of total deformation,stress ratio ranges of peak stresses in compression phase and elastic deformation phase are larger than general hard rock’s ratio ranges in the same phases.When the loading phase converts,acoustic emission rise or descend on a large scale,and then there would be a period of calm.The change laws of ring-down count rate are in contrast with the change laws of event count rate.The jump of energy count rate expresses notable damage inner specimens,the maximum of energy count rate doesn’t always appear at sometime after peak stress.The progress and speed of damage,fracture and fragmentation can be reflected with change laws of ring-down count rate,event count rate and energy count rate.The growth rate of cumulative ring-down count rate increase firstly and then decrease along with loading time,with which the growth rate of cumulative event count rate is in contrast,time domain characteristics expressed by AE signal parameters of each loading phase are similar to mechanical characteristics deformation and fragmentation.