JultikaUniversity of Oulu repository

Abstract

Mining and metals industry extract, process and refine raw materials that are used in every aspect of modern society. It is also a priority sector to achieve a low carbon economy; commodities such as copper, cobalt, nickel and lithium, among others, are essential to developing clean energy technologies and electromobility plans. At the same time, the mining sector is energy-intensive and can have long-lasting impacts on the environment, depending on the exploitation method.

Mining industry represents 7% of the worldwide energy consumption and contributes 10% energy-related greenhouse emission gases. In the latest reports, the actions took for the mining industry to achieve the Paris agreement goals were qualified as insufficient, a problematic scenario, considering that the targets are most likely increase during the next agreement.

Comminution is the most power-demanding stage, using around 50% of the total consumption. In this context, optimisation in comminution processes is one of the biggest challenges in the industry. Geometallurgy is a discipline that aims to address the current challenges of the sector from an integrated mindset.

Geometallurgical models from the perspective of comminution currently face a problem, the lack of a fast and reliable test to allow mapping the distribution of rock properties in ore deposits. The lack of information on comminution parameters contributes to inefficient comminution processes and consequently, higher energy consumption and emitted amounts of GHG (Greenhouse Gasses).

This thesis work presents a methodology to perform breakage tests using a new device called Geopyörä. The research uses the parameters measured by the testing device to derive and validate comminution parameters such as JKDWT Axb, SMC Test® DWi and BWi.

A methodology to achieve the objective of this test was created, allowing to have a procedure for a fast test, requiring approximately 10 minutes per sample, which ultimately results in a low-cost operation. This test uses less than a kilogram of a halve of a meter of drill core to obtain parameters of rock competence and hardness.

The calculation and validation of parameters were carried out in comparison with tests widely used in the industry: JK Drop Weight Test, SMC Test® and Bond ball mill grindability test. The Geopyörä test could deliver reliable results for competence parameters, Axb and DWi (Drop Weight Index), within a margin of error of 7%.

Additionally, a correlation between measured and BBMWi was also developed and validated. The results showed that the Geopyörä was also capable of measuring the Bond grindability parameter within an acceptable margin of error of 10%.