Efficiency of cavity dissolution in rock salt by water submerged jets

To create cavities when dissolving rock salt, it is most expedient to supply the solvent through the nozzles of a perforated pipe in the form of submerged jets. This article examines the physical dissolution of a cavity with water from a stationary nozzle with a diameter of 0.004 m at two constant velocities at the nozzle cross-section. The efficiency of cavity dissolution, which has an almost cylindrical shape with a semi-cylindrical bottom, was analyzed at a nozzle cross-section speed of 8.85 m/s. The obtained results are explained on the basis of the fact that the formed cavity is a short dead-end channel where longitudinal compression acts. The flow in such a channel is caused by the back pressure exerted by its end. And the back pressure, in turn, hinders the development of the jet that flows out of the stationary nozzle, limiting its range. The cessation of significant expansion of the jet is indirectly confirmed by the use of an empirical formula for the distribution of the maximum water velocity along the axis of the jet. Its value at the end of the section of the most intense dissolution of the cavity becomes 8.85 times smaller compared to the speed at the nozzle cross-section. The boundaries of the area of the most intense dissolution of the cavity are determined by the relationship between the depth of the cavity, the diameter of the nozzle, the velocity at its cross-section, and the time of dissolution, which can be used to model the dissolution of cavities at different values of the velocity at the cross-section of the nozzle at its constant diameter. It was found that the relationship between the radius and depth of the cavity is linear. The angle between the boundary of the cavity size change and the axis of the nozzle is 20°23'. These results show that the dissolution of cavities is effective in a limited range of their dissolution time, the limits of which depend on the velocity of the solvent at the nozzle section. To confirm the obtained results, it is necessary to investigate the geometric characteristics of the cavities for other values of the nozzle diameters.