We investigated how the rheological characteristics of a flotation slurry change in response to variations in mineral species, slurry concentration, and particle size; slurry pH; and collector and rheological control reagent concentrations using slurries containing galena, sphalerite, quartz, and kaolinite. The results indicate that reducing particle size and increasing slurry concentration leads to varying degrees of increase in apparent viscosity and yield stress. At the same particle size, the slurry exhibits the following order of apparent viscosity and yield stress: kaolinite > galena > sphalerite > quartz. In addition, as the slurry’s apparent viscosity and yield stress increase, the rheology decreases, creating progressively unfavorable conditions for the flotation of lead, zinc, and other valuable minerals. Furthermore, changes in pH have no significant effect on the slurry’s rheology when the slurry is comprised of gangue mineral. Moreover, galena and sphalerite depict particle agglomeration in the slurry. Ultimately, the addition of sodium silicate as a rheological control reagent substantially enhances the slurry’s rheological properties. This results in a system where problematic minerals like kaolinite are more effectively dispersed, thereby promoting efficient lead-zinc mineral flotation. Regarding the flotation of lead sulfide and zinc minerals, the addition of kaolinite raises the apparent viscosity of the mixed slurry, hindering the flotation of the valuable minerals. Conversely, quartz lowers the apparent viscosity aiding the flotation separation process. Understanding the relationship between flotation conditions and the pulp’s rheological properties can provide valuable guidance for subsequent flotation tests.