Modeling of Vertical Shaft Impact Crushers

Licentiate thesis, 2021

One of the largest products in most civilized societies is concrete used to build various types of constructions. To create this product, a mixture of cement, chemical binders, and rock aggregates are combined and then poured into molds where it hardens. The sand part of the rock aggregates is either from natural sources or manufactured. Vertical shaft impact crushers can be used to create this machine sand but existing models make it hard to plan new sites and achieve a viable replacement to the natural sand.

In this thesis, the use of vertical shaft impact crushers to crush aggregate rock to rounder particles is investigated. The main aim of this is to develop and further the understanding of the relationship between the machine and material properties with respect to the resulting crushed product in an effort to achieve an improved product. In order to gain a better understanding of the underlying mechanics of particle breakage, Discrete Element Method has been used to obtain particle collision energies. Several different product size distribution models have also been used to better predict the behavior of different crushers and feed sizes. To facilitate this, a framework to improve sites has been developed.

The resulting framework simulates existing VSI machines and optimizes the machine parameters with respect to the specified feed material and PSD to create sought products. The framework can also be used to optimize existing sites which increases the effectiveness in terms of minimizing energy usage and waste products.