Effluent valorization in copper hydrometallurgy plant

Copper is commonly produced by hydrometallurgical processes. The production of this metal results in the formation of emissions (unwanted solids, liquids and gases). In this paper, an effluent from a Cu producer company is valorized by means of Fe and Cu recovery.

In the current process, an effluent from the secondary solvent extraction (secondary raffinate) was sent to neutralization plant to be discharged. In this paper a modification of the process is proposed. The secondary raffinate was contacted with TP207 resin for Fe^3 + and Cu recovery. Metals were eluted from the resins using another real effluent (primary raffinate, effluent from the primary solvent extraction) from the same plant.

Experiments for the uptake and elution were carried out in batch and in columns. The effect of pH, resin dosing, and temperature onto metals retention are analyzed. Retention efficiencies (loading capacities) were 50.1% (8.1 mg·g^− 1) for Cu and 54.8% (23.2 mg·g^− 1) for Fe^3 + under the optimal operational conditions (pH = 0.45 and T = 65 °C). These values were confirmed in column tests. It is possible to recover Fe^3 + and Cu from the secondary raffinate, leaving most of Fe^2 + and other elements in solution. The experimental affinities that TP207 showed are: Cu > Fe^3 + > Fe^2 + > Zn.

The elution of Fe and Cu was quantitatively achieved with concentrated H₂SO₄ solution. When acidified primary raffinate was used as eluting solution, an enriched solution containing 14.3 g Cu·L^− 1, 20.3 g Fe^2 +·L^− 1, and 18.6 de g Fe^3 +·L^− 1 was obtained. This enriched primary raffinate can be reintroduced in the process as leaching solution.

So, after the modification of the process, using secondary raffinate as loading solution and acidified primary raffinate as eluting solution, the ion-exchange stage could substitute the external FeSO₄ addition. In addition, 30–80 kg Cu·h^− 1 are reintroduced in the process.