Benefits of semi-inverted hydrocyclones in closed grinding circuit a pilot scale study

Classification plays an important role in the grinding circuit. The benefits of improved classification efficiency on the wet-grinding ball mill circuit have been reported in the past. Despite their poor classification efficiency, hydrocyclones are still the most widely used classifiers in these grinding circuits.

Current research in semi-inverted (SIV) hydrocyclones has shown that these hydrocyclones provide significantly less by-pass of fines than conventional hydrocyclones. In this study, the ore material was classified using a conventional 375 mm hydrocyclone and the SIV hydrocyclone. The hydrocyclone underflow material was used as head feed to the pilot-scale ball mill. Collected data were used to compare the performance of these batch grinding cases and simulations were used to estimate the potential benefits of SIV hydrocyclones in ball mill grinding circuits. Batch grinding tests have shown that the size specific energy (SSE) for generating material below 75 µm was reduced up to 45 % when grinding the SIV hydrocyclone underflow material.

The ball mill circuit simulations have shown that an improved efficiency of the SIV hydrocyclone enables 25–91 % higher throughput compared to the circuit with a conventional hydrocyclone for the same product P₈₀. Even though the product P₈₀ was the same in all cases, the simulation with the SIV hydrocyclone had a product with a narrow particle size distribution that should maximise subsequent flotation recovery.