Rock Engineering at Kiruna Mine – The Change Journey

ABSTRACT: Kiruna mine, located in Northern Sweden, is well-known as a large-scale, highly technical advanced operation. The orebody is vast and the application of sublevel caving (SLC) in transverse layout is forgiving in terms of recovery. Work processes are rock-factory-like. However, over the past 15 years, rock mechanical conditions have become increasingly adverse. In May 2020, a major seismic event with a local magnitude of 4.2 caused severe damage to large parts of the mine. Only very few mines in the world have ever experienced such a large seismic event. Only the event timing prevented loss of life. Production has since then been on a decline and previously reached production figures seem elusive on a first look. These circumstances have been a serious final call for change. Fortunately, the upper management understand the importance of a holistic, sustainable, long-term view on mining. Rock mechanics and seismic considerations are of paramount importance for mine design, production control, and operation practices. Its integration into mine plans with long-medium-short term schedules enables highly coveted reliable production prognoses. The new Rock Engineering organization has a key role to play in this change. A substantial effort is underway to improve SLC performance both from a technical and behavioral perspective. The technical component of the change focuses on developing a barrier pillar, sequences, layouts, support systems and procedures required for mining at greater depths. A rock engineering center facilitates the regular review of the current health status of the mine and allows proactive measures. It also fosters cross-functional work, and it proved to not inevitably slow down processes. On the contrary, by learning on the specific reaction of ground, and given a built-in flexibility in mine plans, specific areas might even allow greater pace. Though the technical aspects of mining at depth are challenging, changing of the way things are done is perhaps even more so. The behavioral component focuses on ensuring that the technical tasks and processes can be assimilated into the day-to-day operation. The bespoken transition process requires management systems and, more importantly, behaviors to be adapted to meet the rigor and discipline required for mining at greater depths. The way of communication itself plays a decisive role also, because individuals or departments may interpret changes and new directives as personal/organizational blame. Often, this is not the case; the past design and work processes might have been ideal given the past conditions. It is fundamental for mining that there is no perfect set-up that works throughout the life of a mine, as mining conditions change with depth and with progressive mining. Given the long lead times to realize changes, a gradual and persistent approach is key. Meanwhile the operation must continue to produce in a way that does not compromise the changes required. Sustainable production targets are required to avoid "mining into a corner". By going through this journey of change and subsequent optimization, there is a great potential for Kiruna mine to become a rock factory once again – but on other conditions.