Treating chalcopyrite flotation concentrates by hydrometallurgical techniques seems to be the most convenient method for leaching copper due to concerns over air pollution and regulations regarding the emission of sulfur dioxide that result from smelting. In this study, the leaching recovery-time trajectories of bulk chalcopyrite concentrate obtained from a flotation plant in the Kastamonu region of Turkey are presented. The effects of various parameters were elucidated in the nitrous-sulfuric acid electrolyte (C_NaNO2:0.05 M–0.15 M, C_H2SO4:1 M) at a moderate temperature (80–120 °C). A high level of copper recovery (98%) from bulk chalcopyrite concentrate was obtained under a total pressure of 6 atm at 120°C within 2 h when using small amounts of nitrite species due to their autocatalytic behavior in acidic solutions. The kinetics were well correlated with the shrinking core model for the diffusion controlled mechanism with an apparent activation energy of 34.06 kJ·mol^–1. Elemental sulfur was the primary leaching product on the mineral surface, as confirmed using XRD and SEM/EDX. The semi-empirical equation explaining the reaction rate under the present conditions was expressed as follows: 1-2/3X-(1-X)^2/3=56.53x10^-4 C_NaNO2 y₀^-0.83 e^{4096.7 t/T}