We consider the application of a nonsmooth discrete element method to geometric design optimization of a balling drum outlet used in production of iron ore balls. The geometric design optimization problem is based on the need for homogeneous flow of balls from the balling drum onto a wide belt conveyor feeding a roller screen (sieve). An outlet with two design variables is investigated and the optimal shape for the given system and production flow is found by exploring the design space with 2000 simulations. (C) 2013 Elsevier B.V. All rights reserved.