Abstract Understanding the geotechnical properties of iron ore tailings is currently one of the major challenges in the mining industry. With transitions from drained to undrained conditions occurring in seconds, recent dam problems have been a challenge to solve with classical soil mechanics, which provides few means to explain how such phenomena develop. There is also an increasing propensity in technical and scientific circles to seek constitutive models that are based on critical state soil mechanics and that allow for the analysis of tailings behaviour. However, there is still a lack of knowledge and information about the critical state properties of iron ore tailings. The present research experimentally and numerically investigated the effectiveness of modelling the behaviour of iron ore tailings. The aim of these experiments was to assess the critical state parameters of tailings from a significant iron ore operation site in Quadrilátero Ferrífero (Minas Gerais state, Brazil). The results indicated that the selected numerical model (NorSand) was adequate to evaluate the behaviour of the studied mine tailings. The numerical results showed consistent adherence to the experimental results of both drained and undrained tests, with deformations below 5% and samples in which the state parameter had a small magnitude.