New Mexico Geological Society Annual Spring Meeting — Abstracts

The Malmberget/Vitåfors mining facility, located in Norrbotten County, Sweden, is the world’s second largest underground iron ore mine, comprised of roughly 20 steeply dipping magnetite-hematite ore lenses, with an underground area of approximately 5 x 2.5km. Since its’ opening in 1892, over 350Mt of ore have been removed from Malberget, and another 350Mt of iron reserves have been declared proven and probable.

The state-owned Swedish mining company, Luossavaara-Kiirunavaara Aktiebolag (LKAB), owns and operates the facility. They have seen an increase in production in the past years, effectively doubling the amount of ore processed at the Vitåfors facility, from 8Mton/year in 1998 to 16Mton/year in 2013, and they intend to maintain this steady increase into the future. Despite these changes, the amount of water used within the system has not increased proportionally, and is not predicted to do so in the future. This is due to increases in process-water recycling, which adds to the demands placed on this water. As the water is reused, the conservative and trace element concentrations grow, affecting the overall water quality. This is of concern, as a portion of this spent process-water is released daily into the local receiving environment, the Lina River.

This discharge to the Lina River represents one of the main losses within the system, and has been sampled with some degree of consistency since 1998. Such is not the case for instances of evaporation and diffuse leakage, both of which have been acknowledged but not quantified. Thus, a water balance for this system is not as straightforward as it may seem. Not only are these losses unknown, but thorough accounting of water use in the mine and processing facility has only been undertaken within the past few years, leaving a number of gaps in the historical record. Additionally, seasonal fluctuations exist in the availability of input water from the primary source: groundwater entering the mine workings. This adds to the complexity of the problem, and highlights the importance of an accurate working model of water use within the system.

This research intends to define and quantify the inputs and losses to the system, as well as determine the degree to which process water recycling impacts overall water consumption. The initial model serves as a foundation for understanding the likely changes that will occur due to seasonal fluctuations and increases in production.