High-efficiency separators .2. Optimizing performance

The development of high efficiency separators promised significant energy savings, increased production capacity, and improved cement quality. However, the results obtained in cement finish grinding mills were sometimes disappointing. Part 1 of this paper reviewed the effects of high efficiency separators on cements; part 2 discuss the selection and operation of high efficiency separators for optimum performance. The first step in obtaining the greatest benefit from a high efficiency separator is to determine whether it would be worthwhile to purchase one at all. The operation parameters of the mill circuit must be optimized. Then analysis of Tromp curves of the separator feed, fines, and tailings will show whether a high efficiency separator could provide any benefit. The entire mill circuit should be considered. Since a high efficiency separator does not recirculate air, it requires a much greater supply of ambient air, which will generally necessitate additional ducts and fans as well as modification to the dust collection system. Modifications to the mill may be beneficial with or without a high efficiency separator. The ball charge and grading may require adjustment to suit the new milling conditions. After the equipment is installed, the feed rate and other milling conditions should be optimized. The operating conditions that produce the best quality cement are not automatic consequences of the installation of a new separator, but must be determined by trial and error. It may be necessary to operate at less than maximum efficiency in order to produce a cement that is acceptable to the user.