Flotation of Copper Polymetallic Ore: Solving the Challenges of Complex Ore Separation

Copper polymetallic sulphide ores are an important source of non-ferrous metals, typically characterised by close mineral association, fine grain size, and partial oxidation and alteration. Due to issues such as overlapping mineral floatability, the generation of slime during grinding, and significant variations in the physical properties of oxidised minerals, traditional processes such as priority flotation and mixed flotation suffer from shortcomings including lengthy processing times, high reagent consumption, poor separation indices and high production costs, making them ill-suited for complex, difficult-to-process ores. Consequently, the industry has developed six novel flotation processes that effectively overcome the bottlenecks of traditional mineral processing technologies.

The asynchronous flotation process has been optimised based on mixed flotation and isoflotation technologies. It employs a two-stage flotation model, utilising differences in the flotation rates of various minerals to achieve synergistic flotation. This process offers strong compatibility and a streamlined workflow, reducing mineral intergrowth and circuit losses, and is suitable for the beneficiation of copper polymetallic ores requiring the production of mixed concentrates.

Flash flotation adheres to the ‘early and rapid recovery’ principle, recovering coarse-grained minerals and intergrown bodies at an early stage, and treating the liberated coarse particles directly as finished concentrate. This process reduces grinding load, eliminates slime contamination caused by over-grinding, and minimises the loss of valuable mineral streams. It is particularly suitable for complex copper ores characterised by uneven particle sizes, susceptibility to slime formation, and the presence of associated precious metals such as gold and silver.

Speed-differentiated flotation achieves precise separation based on differences in mineral flotation speeds. It not only rapidly recovers highly floatable minerals, thereby reducing secondary slime contamination and improving concentrate quality, but also ensures stable production and reduces energy consumption. This process is suitable for ores with uneven mineral distribution that require regrinding of coarse, fine and middlings concentrates. Its drawbacks include significant dependence on ore properties and relatively high reagent consumption.

Branched flotation optimises separation efficiency through slurry diversion and complementary product streams. It improves slurry and froth structure, reduces gangue entrapment and enhances concentrate grade. This process offers high reagent utilisation, saving one-third of reagent consumption compared to conventional flowsheets, requires no significant additional equipment, and is suitable for difficult-to-process copper ores characterised by low grade, fine-grained distribution and high oxidation rates.

Carrier flotation utilises coarse-grained minerals as carriers to float fine-grained minerals, thereby overcoming the lower size limit of traditional flotation. It is compatible with conventional equipment and reagents and offers high flexibility in separation. However, this process is difficult to control in terms of parameters and is suitable for a limited range of ore types; it is primarily divided into two categories: conventional carrier flotation and self-carrier flotation.

Flocculation flotation encompasses two processes: selective flocculation and shear flocculation. By utilising reagents or mechanical agitation to promote the agglomeration of fine-grained minerals, it effectively resolves the challenge of recovering fine-grained slimes. It offers the advantages of high selectivity, simple equipment and low pollution, and has already been implemented in industrial applications for the beneficiation of fine-grained copper sulphide and tin ores.