© The Authors, published by EDP Sciences, 2017. This paper illustrates the application of ultra-fast magnetic resonance imaging (MRI) as a noninvasive tool to study the dispersion of a dry, static granular bed by the injection of a liquid. Spatial distributions of undispersed grains (poppy seeds) and injected water were independently imaged at sub-millimetre resolution in 2D with ultra-fast MRI techniques. A liquid jet was observed above the bottom injection orifice, complementing optical imaging. Co-registration of the grains and water images enables the interaction of the static grains and of the liquid jet to be observed for the first time in situ. This visualization of the dispersion process can be used to identify optimal process parameters for a fast and uniform dispersion and to validate quantitatively numerical granular-fluid simulations [1].