Characterization of the Kiirunavaara iron ore deposit for mineral processing with a focus on the high silica ore type B2
Research output: Thesis › Doctoral Thesis
The Kiirunavaara iron ore deposit shows a rather low content of silica (ca. 2.3 to 3.3% SiO2) but the silica grade is expected to increase in the deeper parts of the deposit. A project called “Silica in the Mine” was started in 2007 with the target to develop a simplified method in laboratory scale to predict the energy consumption and SiO2 grade in the magnetite concentrate at the industrial scale and further predict the physical properties of the crude ore with respect to mineral processing characteristics. The first target of this study was to control and compare the comminution and mineral processing tests in relation to the “Silica in the Mine” project carried out at LKAB’s mineral processing laboratory to the comminution and mineral processing tests at the laboratory of the Institute of Mineral Processing, Montanuniversitatet Leoben. For the purpose of this study, three samples were selected representing three main ore types (B1, B2, D) of the Kiirunavaara iron ore deposit. They were first were first ground according to the “Optimized Comminution Sequence” (OCS) method. It can be concluded that these three samples, representing different ore types, show a difference in their breakage behavior based on the ore characterization data defined by the differences in the particle size distribution within comminution products, as well as in differences in the mass-specific energy consumption. It is significant to note based on the information from the comminution test that there might be a deviant breakage characteristic in relation to the iron ore from the Kiirunavaara deposit, which can be explained can be explained with the crystal structure of magnetite. Furthermore, a separation with Davis magnetic tube was a crucial part of the mineral processing test to study the liberation of magnetite and silicates. As it was evident that the amount of the high-SiO2 ore type B2 increases, detailed mineral processing tests were carried out for process mineralogical characterization of this ore type at the laboratory of the Institute of Mineral Processing in summer of 2010. These tests combined geological, mineralogical, and geochemical information with mineralogical processing characteristics such as energy consumption, particle size distribution, and liberation and intergrowths. The essential part of this study was the mineralogical investigations using automated mineralogy (QEMSCAN®) to study the modal mineralogy, the distribution of silicates in the different particle size classes after comminution, the deportment of silicon (Si) between various silicates and degree of liberation and intergrowth of magnetite and silicates. An important result of this study was the discovery of two separate subtypes within ore type B2 based on the occur of actinolite in the subtype B2-a. This can be considered as the cause of the difference in grindability (i.e., characteristic) of these two subtypes.
|Translated title of the contribution||Charakterisierung der Kiirunavaara Eisenerzlagerstätte bezüglich Aufbereitbarkeit mit Schwerpunkt auf dem silikatreichen Erztyp B2|
|Publication status||Published - 2015|