A proper evaluation of the mechanics of tailings is a crucial step toward the geotechnical analyses required throughout the project lifecycle of tailings storage facilities. In particular, an essential aspect of behavior is the stress level dependency of the stress-deformation constitutive relationships, which needs to be assessed when a new dam is raised or when a new deposition of tailings occurs. For that purpose, the present paper addresses the response of zinc tailings under triaxial compression tests with confinement pressures ranging from 20 kPa to 4000 kPa. Particle breakage was assessed by determining the grain size distribution in some specimens sheared at specific confining pressures. The results indicate the existence of multiple-strength envelopes in which the critical stress ratio (M) varied from 1.58 for the lowest confinement levels to 1.20 for the highest pressures. This was accompanied by a substantial increment in the acceptable content of the material, resulting from grain crushing occurring at higher pressures.