Product Flake Formation and Treatment of HPGR Crusher

The HPGR product emerges from the compression zone as a compacted cake or flake. The coherence of the flake is a function primarily of the ore type and moisture content, and also of the operating pressure of the machine. Generally, competent flakes are produced with softer materials or those with a high clay or moisture content—kimberlites, for example—while hard, primary ores tend to produce fragile flakes, even at relatively high moistures and pressures.

Depending on flake competency and downstream processing requirements, a dedicated unit operation for deagglomeration of the flake product could be required, and this is a significant consideration in flowsheet development. Kimberlite flakes normally must be intensively deagglomerated in wet rotary-drum scrubbers, and then screened to ensure efficient removal of fines before downstream processing, usually in a heavy media separation operation. By contrast, the flake in a hard, primary-ore application might require no separate deagglomeration, being adequately broken down by handling in chutes and bins and on conveyors, so that acceptable efficiencies are achieved in normal screening.

The need for, and nature of, a dedicated deagglomeration step in the comminution flowsheet can normally be assessed by testing. Formats has developed a standard flake competency test specifically designed to determine whether separate deagglomeration is required ahead of further processing.