Study on the shape and specific surface area characteristics of blasting gravel particles of limestone in Hangudi quarry of Baihetan

A number of blasting gravel particles of limestone with the particle size ranging from 5 to 1 000 mm were randomly selected in the Hangudi quarry and then were classified into 5 groups according to the form. The particles outline projections were obtained by the 3D laser scanner and the self-designed measurement system, and the shape parameters of blasting gravel particles were calculated and analyzed by image processing technology and SPSS. The change law of the specific surface area of the 5 types of blasting gravel particles was analyzed, and the cumulative distribution curve of the specific surface area was drawn. The results show that the proportions of hexahedral, pentahedral, tetrahedral, flat and elongated, and irregular polyhedron particles are respectively 52%, 17%, 13%, 13% and 5% in muckpiles. The hexahedron particles are most similar to a sphere in shape, followed by pentahedron and tetrahedron particles. The roundness and sphericity of 5 types of gravel particles increase with increasing the particle size, and the angularity is stronger as the particle size decreases. The surface texture of the gravel particles selected is similar and the specific surface area is in the range of 179.84-3.82 mm2/g with a specific charge of 0.37-0.38 kg/m3. The differences of the specific surface area between 5 types of gravel particles can be ignored in the case of the same particle size, and the specific surface area decreases exponentially with increasing the particle size. The cumulative distribution curve of the specific surface area can be obtained by using the gradation curve and the specific surface area curve. © 2019, Science Press. All right reserved.