Probabilistic Analysis of the Hard Rock Disintegration Process

K Frydrýšek

doi:10.14311/1041

Abstract

This paper focuses on a numerical analysis of the hard rock (ore) disintegration process. The bit moves and sinks into the hard rock (mechanical contact with friction between the ore and the cutting bit) and subsequently disintegrates it. The disintegration (i.e. the stress-strain relationship, contact forces, reaction forces and fracture of the ore) is solved via the FEM (MSC.Marc/Mentat software) and SBRA (Simulation-Based Reliability Assessment) method (Monte Carlo simulations, Anthill and Mathcad software). The ore is disintegrated by deactivating the finite elements which satisfy the fracture condition. The material of the ore (i.e. yield stress, fracture limit, Young’s modulus and Poisson’s ratio), is given by bounded histograms (i.e. stochastic inputs which better describe reality). The results (reaction forces in the cutting bit) are also of stochastic quantity and they are compared with experimental measurements. Application of the SBRA method in this area is a modern and innovative trend in mechanics. However, it takes a long time to solve this problem (due to material and structural nonlinearities, the large number of elements, many iteration steps and many Monte Carlo simulations). Parallel computers were therefore used to handle the large computational needs of this problem.

Highlights

Scientific and technical developments are affected by the growing demand for basic raw materials and energy
The main focus is on modeling the mechanical contact between the bit and the ore, see Fig. 1
Let us consider the “Simulation-Based Reliability Assessment” (SBRA) Method, a probabilistic approach, in which all inputs are given by bounded histograms

Summary

Introduction

Scientific and technical developments (in all areas of world-wide industry) are affected by the growing demand for basic raw materials and energy. The provision of sufficient quantities of raw materials and energy for the processing industry is the main limiting factor of further development. It is very important to understand the ore disintegration process, including an analysis of the bit (i.e. excavation tool) used in mining operations. The main focus is on modeling the mechanical contact between the bit and the ore, see Fig. 1

Finite element model of the ore disintegration process

Solution – SBRA method in combination with FEM

Results – stochastic evaluation

Comparison between stochastic results and experimental measurements

Conclusions