The paper considers a complex mass transfer, consisting of local mass transfers, during the construction and operation of a tank-work under the hydrodynamic effect of a solution on rock salt with various separation of the boundary layer (Malyukov in Online 16:25–40, November 2021; Malyukov V.P. Physical processes and technologies for the construction of underground workings-tanks under the hydrodynamic effect of solution on rock salt: monograph / V.P. Malyukov - Moscow: RUDN, 2021. - 299 p.;): diffusion mass transfer (mass transfer) with a concentration separation of the boundary layer, mass transfer of insoluble inclusions (different in composition, scattered and from interlayers), vortex mass transfer, separation mass transfer (when salt plates are separated from crystals), gas mass transfer (when gas is released from salt). Local mass transfer processes include fluid infiltration into rock salt and convergence (a change in the volume of production when the rock salt of the production zone is displaced into the tank space), cyclic infiltration and convergence. Similar processes occur in the chambers (caverns) of brine mills. © 2022, The Author(s), under exclusive license to Springer Nature Switzerland AG.