Tailings management represents a critical challenge for the mining industry, due to increasing environmental and safety concerns related to tailings disposal, and the continuous upscaling of mining operations. The process of dewatering allows to separate the tailings into a solid – like material suitable for deposition, and water to be reused in the operations. Among the various technologies available for this purpose, filter presses are widely used, as they are capable of achieving high degrees of dewatering, while handling large volumes of material.

The mining sector requires increasingly demanding performances in terms of cake residual moisture and material throughput. Therefore, a deep understanding of the filtration process, as well as the physical – chemical properties of the slurries are crucial for optimizing operating parameters and achieving the required performance targets. The mineralogical composition of the slurries is a critical factor affecting the filtration performances, particularly in terms of filtration time and degree of dehydration.

The Diemme Filtration R&D Laboratory is actively working on gaining a deeper understanding of the correlation between the mineralogical composition – especially the content and type of clays – and the filtration performances. Previous works clearly show how the presence of swelling clays, even in small quantities, have a drastic impact on the filterability and dewatering level. Therefore, quantify the effect of the mineralogical composition is of primary importance in the field of tailings management.

In an effort to achieve this goal, this article presents two case studies related to filtration tests performed on samples obtained from operating mining plants. One case focuses on the influence of the presence of a swelling clay, which worsen the dewatering performance by cake blowing; the other on the effect of the presence of clays on the filtration time. Both studies highlight the critical role of clays on the filtration performances and emphasize the importance of quantifying the effect of clay type and content, with the aim of gaining a deeper understanding of tailings properties and achieving precise control over the filtration performances.