In this study, the effects of operating variables and sluice geometry on the separation performance of pinched sluices were investigated. Tests were carried out on a closed circuit experimental setup under varying feed flow rate, splitter position, feed % solids and slope angle conditions. Seven pinched sluices of different geometry were manufactured and tested in the study. An artificial mixture of magnetite and quartz was used as the test material. Results showed that splitter position controlled the amount of solids taken into concentrate, hence, recovery and grade. An increase in feed flow rate deteriorated the performance. Within the range studied, deck slope and feed % solids did not show significant correlation with performance criteria. However, it was found that underflow thickening ratio increased with decreasing deck slope and feed % solids. For high flow rates, larger sluices had better performance. Increasing pinch angle of sluice had an adverse effect on the performance, particularly at high flow rate range. The effect of sluice length on the performance was found to be insignificant. (C) 2002 Elsevier Science Ltd. All rights reserved.