The paper describes the five heuristic inputs required for our evolutionary minerals design system, which has shown a potential for creating flowsheets of high profit. The effect of each of these heuristic decisions (such as whether to recycle or to install a grinder at a specific point) is demonstrated by examples, showing how objectives such as high profitability, circuit simplicity, or placement of grinders or classifiers may be achieved. Although such design systems cannot guarantee reaching a global optimum, they give users important control by allowing incorporation of choice judgement and industry experience and preferences into a design, which may in practice be more useful.