Copper mine tailings reprocessing process?

In order to improve resource efficiency, mineral processing residues, especially tailings, have become the focus of research. Tailings still contain varying amounts of unextracted valuable elements and minerals that are not economically beneficial in the production process. So what is the recycling process of copper mine tailings?

1) Magnetic separation of the magnetic and non-magnetic parts of the tailings.

2) The magnetic and non-magnetic materials are separately leached in a mixing tank with dilute sulfuric acid (less than 5%) in a continuous or intermittent manner (several hours).

3) Hydrocyclone sedimentation to separate solid and liquid (copper-rich solution).

4) Wash the concentrate to remove the remaining copper (dilute copper solution).

5) Deposition of non-magnetic parts (finer than the original tailings material).

6) Further concentrate and clean the copper solution to produce intermediate products, or produce cathodes by electrolytic deposition.

Early cost estimates for tailings reprocessing indicate that operating expenses can be reduced by 40% and capital expenditures by 50% for a flotation plant with a capacity of 500 tons/day. For tailings with Fe2O3 grade >30%, the more economical treatment method is to concentrate magnetite. Due to the low operating expenses and capital expenditures of magnetic separation, magnetite in tailings is a more profitable commodity.

If the copper oxide content of the tailings is high, leaching with dilute sulfuric acid may be a viable alternative. In this case, the advantage of leaching is a high recovery rate of 80% and the option to produce cathode copper from a rich leaching solution rather than a (pre-) concentrate that requires further treatment. The disadvantage of leaching is that the acid can reduce the particle size of the material. This may lead to some problems with redeposition, which must be investigated in more detail in pilot plant studies.