<p>The composition of high sulfur residue in zinc smelting is complex and contains many valuable components and toxic elements. The harmless treatment and comprehensive utilization of resources are significant. This study proposes a cavitation and dissociation process to achieve the synergistic extraction of valuable components and the safe detachment of harmful elements in high-sulfur residue from zinc smelting. Numerical simulation was used to visualize each stage. By constructing a gas-liquid two-phase flow numerical model of the cavitation and dissociation reactor, the distribution and motion laws of the gas–liquid phases inside the reactor are revealed. The optimal two-phase flow, turbulence, and interphase force models were selected through PIV experiment. Based on the theories of cavitation and dissociation and two-phase flow models, a three-phase numerical model of gas–liquid–solid within the reactor was established. Using this three-phase numerical model, the effects of dissociation time, reactor temperature, gas flow rate, and pulp concentration on the particle size distribution of the material at the outlet of the reactor model were investigated, revealing the laws of high sulfur residue cavitation and dissociation. The study results provide a theoretical basis and technical support for the efficient recovery of elemental sulfur from high-sulfur residue.</p>