| Metal mineral resources are an important and indispensable resource in the development of the national economy,and along with the year-on-year increase in the gross national product,the demand for metal mineral resources is also increasing year after year.Hard rock crushing is a very important part of metal mineral resources mining.At present,the main methods of hard rock crushing are mechanical rock breaking and explosive blasting,but mechanical crushing of hard rock has serious tool wear and low crushing efficiency for strong hard rock,while explosive blasting can produce toxic and harmful gases and noisy flying rocks,and explosives are dangerous to transport and store.Therefore,the development of new safe and efficient rock breaking technology and equipment has always been a hot issue of concern.High-voltage electric pulse discharge rock breaking technology has the advantages of controlled energy and no toxic and harmful gas generation,and is expected to become a new way to break hard rock.In this paper,we have studied the experimental method of breaking hard rocks by high voltage electric pulse discharge and carried out experiments on breaking hard rocks such as red sandstone and granite by analyzing the effects of specimen size,discharge voltage and physical and mechanical parameters on the effect of breaking hard rocks by high voltage electric pulse discharge in terms of breakdown characteristics,rupture pattern and fragmentation distribution.as follows.(1)A method of using high-voltage electric pulse technology for crushing hard rocks in an indoor air environment was designed to verify the feasibility of the scheme,and the mechanism of high-voltage electric pulse discharge crushing hard rocks in an air environment was discussed.(2)By means of the controlled variable method,experiments were carried out on red sandstone and granite with different diameters and thicknesses of circular specimens to study the effect of hard rock diameter and thickness on the breaking effect of the pulse discharge.(3)Different charging voltages were applied to red sandstone and granite to analyse the effect of voltage on the breaking effect of high voltage electric pulse discharge on hard rocks,and it was found that increasing the voltage could enhance the breaking effect,but there was an optimal voltage value.(4)Using granite,basalt,magnetite quartzite and two types of red sandstone as research objects,pulse discharge breakdown experiments were carried out on five specimens in the electric blasting system,and the effects of physical and mechanical parameters such as specimen density,wave velocity,uniaxial compressive strength,tensile strength,elastic modulus and Poisson’s ratio on breakdown voltage and breakdown field strength were investigated,and the results showed that breakdown voltage and breakdown field strength were influenced by uniaxial compressive strength,tensile strength and Poisson’s ratio.(5)Hierarchical analysis was used to analyse the breaking effect of the five hard rocks.The weight coefficients of the six factors of uniaxial compressive strength,tensile strength,Poisson’s ratio,voltage,diameter and thickness on the breaking effect were calculated,and the electroburstability of the five hard rocks was initially discussed. |
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