Mining method evaluation and dilution control in Kittilä mine

• Main Author: Tommila, Eero
• Other Authors: van Wageningen, André, Insinööritieteiden korkeakoulu, Rinne, Mikael, Aalto-yliopisto, Aalto University
• Format: Master Thesis
• Language: English
• Published: 2014
• Subjects: gold; mining; mining method selection; dilution control; stope optimization; Kittilä; Northern Finland
• Online Access: https://aaltodoc.aalto.fi/handle/123456789/13127

Kittilä mine is a gold mine located in the Northern Finland. It began producing as an open pit mine but nowdays all the production comes from underground mine. The underground mining method was defined during the feasibility study with limited information. With the experience from the underground mining and more rock mechanical and geological data, this thesis was conducted to study if there could be more cost effective method for mining the ore and how to reduce the dilution. The study is divided into two parts: dilution control and mining method selection. Dilution control was done by identifying the reasons for dilution and examining their impact on Kittilä mine. After this, measures could be developed to decrease dilution and improve predictability. Mining method selection was performed by doing preliminary method selection with traditional mining method selection tools. This yielded several methods, which applicability for Kittilä mine was assessed by terms of safety, suitability, production, dilution & recovery and flexibility. Preliminary selection was followed by stope design, where numerical and empirical methods were used to find stable dimensions for stopes. Stope dimensions, different sequence patterns and level designs were used to create mining scenarios for the deeper, undeveloped parts of the mine. These scenarios were finally compared economically to find the most cost effective solution. Furthermore, three different level heights were compared. To improve the drilling accuracy it is recommended to survey all the drillhole collars and inclination and redrill the ones that do not meet required criteria. The deviation of the holes can be decreased by using down-the-hole hammer drills instead of top hammer drills. The dilution prediction could be improved by gathering more rock mechanical and geological data. The gathering of this data and utilizing it when designing stope limits could decrease the dilution. The dilution related to overcuts and undercuts can be prevented by systematically ...