Optimisation Analysis of Beneficiation Processes for Large-flake, Fine-grained and Crystalline Graphite

In graphite mine beneficiation, the physical properties of different types of graphite minerals vary greatly, and the challenges faced in beneficiation are entirely distinct: large-flake graphite is prone to breakage and wastage; fine-grained graphite is difficult to separate; and crystalline and microcrystalline graphite is difficult to liberate. Dedicated beneficiation processes for these three types of graphite have now been successfully implemented, with highly impressive practical results.

Large-flake graphite possesses the highest economic value, but the flakes are extremely prone to fracturing during grinding, which directly reduces product grade. A targeted multi-stage roughing process, combined with scavenging and concentrating stages in a graded flotation circuit, is employed. Grinding intensity is strictly controlled throughout the process to fully preserve large graphite crystals. This mature process ultimately achieves a stable graphite concentrate recovery rate of 97.54 per cent, maximising the preservation of high-value flake resources.

Fine-grained graphite particles are minute and difficult to capture fully using conventional flotation, resulting in significant metal loss. Australian mines employ an enhanced coarse grinding pre-treatment combined with a multi-stage regrinding and re-selection process, whilst optimising flotation reagents and agitation conditions to effectively recover fine graphite particles. The overall concentrate recovery rate for this process is consistently 92.46 per cent, significantly reducing metal loss in tailings.

Cryptocrystalline and microcrystalline graphite features fine crystals and dense embedding, making it difficult to purify through a single flotation stage alone, and making it challenging to meet fixed carbon standards. The laboratory-optimised process involves a single roughing stage to remove a large amount of gangue, followed by seven rounds of staged regrinding to fully liberate the minerals, and eight stages of sequential scavenging to gradually purify the product. Following this treatment, the fixed carbon content of the graphite concentrate was increased to 85.21 per cent, fully meeting the standards for industrial raw material use.

A uniform mineral processing flow sheet cannot be applied across different graphite ores; only by tailoring a staged grinding and flotation scheme based on flake size and crystal morphology can both recovery rates and concentrate quality be optimised.