Energy requirement for rock breakage in laboratory experiments and engineering operations:a review

Based on the review of a wide range of literature, this paper finds that: (1) the average specific surface energy of various single crystals is only 0.8 J/m². (2) The average specific fracture energy of the rocks with a pre-crack under static cleavage tests is 4.6 J/m². (3) The average specific fracture energy of the rocks with a pre-cut notch but with no pre-crack under static tensile fracture (mode I) tests is 4.6 J/m². (4) The average specific fracture energies of regular rock specimens with neither pre-made crack nor pre-cut notch are 26.6, 13.9 and 25.7 J/m² under uniaxial compression, tension and shear tests, respectively. (5) The average specific fracture energy of irregular single quartz particles under uniaxial compression is 13.8 J/m². (6) The average specific fracture energy of particle beds under drop weight tests is 74.0 J/m². (7) The average specific fracture energy of multi-particles in milling tests is 72.5 J/m². (8) The average specific energy of rocks in percussive drilling is 399 J/m³, that in full-scale cutting is 131 J/m³, and that in rotary drilling is 157 J/m³. (9) The average energy efficiency of milling is only 1.10%. (10) The accurate measurements of specific fracture energy in blasting are too few to draw reliable conclusions. In the last part of the paper, the effects of inter-granular displacement, loading rate, confining pressure, surface area measurement, premade crack, attrition and thermal energy on the specific fracture energy of rock are discussed.