Is an 80th Percentile Design Point Logical?

摘要

Clearly a plant designed only to treat average ore at the nameplate rate will fail to achieve nameplaternin any typical year. To insert the necessary capability to achieve nameplate it is common processrnengineering design practice that plant must be able to treat an ore with 80th percentile value (hardnessrnor competence values for example) at the nameplate rate. In the author’s experience, apart from arncouple of notable cases, this has been applied reasonably well as a principal, and with widespreadrnsuccess. However, in a number of recent instances it became clear that the use of the 80th percentilernnumber would have resulted in significant under design of the plant. This paper makes the case thatrnthe 80th percentile, as a principal, has can have serious flaws and its use needs to be assessed on a casernby case basis. The discussion in this paper is the first step in developing a new design principal, andrnthe associated methodology for selection of a design value, that will ensure plants are designed tornachieve their nameplate capacities.