Enhanced recovery of low-grade copper ore and associated precious metals from iron tailings: A case study in China

In the processing of copper and precious metal recovery in a mine in Chengde, Hebei Province, the decrease in copper mineral content and finer grain size distribution of the selected ores have caused challenges in the existing milling process. This has led to difficulties in achieving significant dissociation of chalcopyrite, resulting in decreased separation efficiency of copper and associated precious metals. Particularly, there is a notable loss of precious metals in the flotation tailings. Using BPMA and other detection equipment, the occurrence state, distribution patterns, and liberation degree of copper and associated precious metals in iron tailings were investigated. Subsequent flotation experiments examined the impact of grinding regimes on mineral liberation and reagent regimes on mineral enrichment. Subsequently, flotation experiments were conducted to examine the influence of grinding regimes on mineral liberation and reagent regimes on mineral enrichment. The research findings revealed that copper and precious metal contents in iron tailings are extremely low and finely disseminated within gangue minerals, posing challenges for liberation. Under the optimal conditions determined from flotation experiments, a laboratory closed-circuit process consisting of one rougher, one scavenger, and two cleaner stages yielded a copper concentrate with a grade of 11.33 %, a recovery efficiency of 66.95 %, and containing 9.42 g/t gold, 52.72 g/t silver, 2.78 g/t platinum, and 8.46 g/t palladium. The SEM-EDS analysis further emphasizes the necessity to tailor grinding and flotation processes to optimize the liberation and subsequent recovery of these valuable minerals, avoiding excessive grinding of gangue minerals which could negatively impact flotation performance.