Experimental study of fractional composition of pieces of brittle material during crushing in a single-roll crusher with block stop on the roll

Abstract

Processing of bulk materials used in metallurgical industry to obtain necessary grades of size requires application of crushing machines, including a single-roll type. Indicators of crushing process are degree and efficiency of crushing. Degree of crushing is estimated by the ratio of size of initial crushed and resulting pieces, which depends on size of the gap between a roll and a fixed jaw. The Siberian State Industrial University has patented, designed and manufactured a pilot unit, which is a single-roll crusher with block stop on the roll to study crushing process. A series of experiments on different samples (in shape, size and strength) crushing was carried out on the developed unit. Technique of the experiment and the design of a single-roll crusher with block stop on the roll were described. Results of destruction of the samples of isotropic material made of sand-cement mixture of regular (spherical) shape are presented. Samples from isotropic material allow comparison of analytical conclusions of determining position of the plane of action of maximum tangential stresses with experimental data. Samples of anisotropic material (for example, ferroalloy) were also destroyed. It was experimentally determined that the larger is clearance between the roll and the fixed jaw, the larger is the size of fraction of finished product and over-grinding is less than after crushing the same piece with a smaller clearance. The degree of crushing in a single-roll crusher with block stop on the roll cannot be equal to 4 or more. It was proved that destruction of isotropic materials occurs along the plane of action of maximum tangential stresses. Anisotropic materials are destroyed, depending on size of clearance between a roll and a jaw, both on the plane of action of the maximum tangential stresses and on the planes of least resistance.