The force application situation and method of crushing machinery

The force application of crushing machinery can be divided into crushing, splitting, breaking, grinding, and impact. Any type of crusher and grinding machine does not only use one force to crush ore, but usually uses a certain force as the main force and cooperates with other types of forces. Therefore, the force exerted by the crushing machine on the ore is complex. The application of mechanical force varies, and the types of ore strength that should be considered also vary. For crushing, the compressive strength of the ore should be considered; For breakage, attention should be paid to the bending strength of the ore; When grinding and stripping ore, its shear strength should be considered.

Crushing machinery uses its working components to repeatedly apply dynamic loads to ores, thus having a certain impact effect. When the ore is impacted, its impact strength should be considered. For example, when ore is crushed between the teeth of a collar crusher, it is subjected to splitting action, and the anti splitting strength of the ore is about 1.2 times the tensile strength. When an object collides with another object, the kinetic energy of the force actor rapidly transforms into the deformation potential energy of the force actor, and a local concentration of stress is formed at the point of impact. As the impact speed accelerates, the deformation does not have enough time to extend to all of the impacted object, and a considerable local stress occurs at the impact site. Therefore, the destructive effect of dynamic load is greater than that of static load. If the load exceeds the fatigue limit, increasing the number of repeated impacts can reduce the stress required for failure to occur. Therefore, using high-frequency impact method to crush ore can achieve good results such as low power consumption, high crushing ratio and light over crushing, and easy occurrence of sufficient dissociation in coarser particle sizes.

In recent years, the emergence of impact crushers and vibrating ball mills has the characteristic of high-frequency impact. Due to the diverse composition of minerals, their physical properties vary greatly. Sometimes, there are significant differences, some being broken into coarser particles, while others are finer. This phenomenon is called selective fragmentation. The fundamental reason for selective crushing is that the mechanical properties of various minerals in the ore vary greatly, and the external factor is the performance of the crushing machinery. For example, impact crushers and self grinding machines are more prone to selective crushing. By utilizing the phenomenon of selective crushing, it is possible to first separate the particles that have already been dissociated and contain more minerals, without waiting for all the ore materials to be ground to the same fineness, which is beneficial for reducing over crushing.

The force application method of the crusher should be suitable for the properties of the ore. The principle of selection is: for hard ore, use bending and impact to crush it. If it is ground and peeled, the machine will suffer severe wear and tear; For brittle ores, bending and splitting are more advantageous. If a grinding brake is used, there will be too much fine powder in the product; For ores with high toughness and toughness, it is more reasonable to use grinding and stripping method. The crushing process does not occur automatically and is irreversible. External forces exert work on the ore, overcoming the cohesive forces between its internal particles, in order to achieve crushing. When external forces work on the ore and cause it to break, the potential of the ore material also increases. Therefore, the theory of crushing power consumption is essentially to elucidate the relationship between Yang Jingong in the crushing process and the potential changes of the ore before and after crushing. When crushing materials, their strength, feed particle size, product slope, and energy consumption are measurable. Therefore, various energy consumption theories determine their relationship, which is the common point of various crushing energy consumption theories.