The best throughput policy for an existing copper concentrator with conventional grinding systems has been studied under a number of technological and financial preconditions. Simple empirical models based on data gathered in a number of sampling campaigns in a major Chilean concentrator are used to describe the behaviour of the grinding and flotation units and the influence of the particle size on flotation efficiency. The analysis demonstrates that the throughput maximising the profit is the best compromise between metallurgical efficiency and revenues from concentrate sales. The sensitivity of the profit with respect to the copper metal price indicates that there is a weak relationship between optimal plant capacity and copper price. An application example is used to explain the increasing nominal capacity of the installations coming into operation and the expansion policy of some existing concentrators.