The copper sulfide precipitation is a selective and efficient method for the recovery or removal of metals. However, the suspension behavior, and particularly the aggregation performance of generated precipitates, is still under investigation. In this context, the current work focuses on the assessment of the aggregation size evolution of copper sulfide precipitates at different operational conditions, based on FBRM. This method can measure noninvasive, in-situ and real-time the particle aggregation evolution in a suspension. A copper sulfide precipitation reaction was carried out using an experimental design varying pH, sulfide dosage, and copper concentration in the feed solution. The copper concentration had the most significant effect on the aggregates size, showing a high aggregation behavior above 1000 mg/L Cu, instead 200 mg/L where this tendency was negligible. This study is the first one to use FBRM in copper precipitates and its results can be used to support future studies to improve solid-liquid separation processes. (C) 2020 Elsevier B.V. All rights reserved.