This paper presents the applied process of evaluation the exploitable reserves of lead and zinc at the Ribnik deposit, using the Whittle software, according to the criteria of maximum net present value and maximum deposit utilization, as a necessary prerequisite for responsible management of mineral resources. In addition to the mentioned general criteria, a specific criterion, related to the requirement of the technological process of flotation processing that the input minimum average content of equivalent metal (Zn + PbEqZn) in the ore should be 2.5%, was applied in the evaluation the exploitable reserves.