Global sulfuric acid plants produce millions of tons of pyrite roasting residues (PRR, primarily Fe₂O₃) each year. If untreated, these residues are an environmental liability—yet they often contain valuable metals such as copper and zinc.
At PRS, we use precision-controlled selective acid leaching to achieve high metal recovery rates while fully utilizing iron residues. This transforms what was once waste into high-value, marketable products, aligning with the principles of the circular economy.
Core Technology: Selective Acid Leaching
Our method exploits the solubility difference between copper/zinc oxides and iron oxides in sulfuric acid.
- Acid Control:Dilute H₂SO₄ dissolves Cu/Zn within a tightly controlled pH range.
- Iron Suppression:Maintaining a reducing environment (low ORP) minimizes Fe³⁺
- Dynamic Neutralization:Recycled iron-bearing precipitates (e.g., jarosite) help regulate acidity.
Engineering Insight: “Endpoint pH control is critical – even a 0.5 deviation may double iron dissolution.” – PRS Engineering Team
Closed-Loop 7-Step Recovery Process
|
Step |
Process |
Key Details |
|
1 |
Feed Preparation |
Crush to 150 mesh; slurry density: 30% ± 5% solids |
|
2 |
Selective Acid Leaching |
95% Cu/Zn extraction, <10% Fe dissolution |
|
3 |
Solid-Liquid Separation |
Vacuum belt filtration + 3-stage washing |
|
4 |
Iron Removal |
Hydrolysis (low cost), Jarosite (acid recovery), Goethite (eco-safe), Hematite (premium pigment) |
|
5 |
Cu/Zn Separation |
Cu SX-EW: >99.5% Cu; Zn purification: Zn-dust cementation + SX, >99.9% impurity removal |
|
6 |
Zero-Liquid Discharge |
RO membrane + evaporative crystallization for water recycle |
|
7 |
Residue Valorization |
>60% Fe residue → ironmaking feedstock or cement additive |
Key Advantages of PRS Technology
1. High Metal Recovery
- 98% Cu and >95% Zn recovery rates
- 99% pure cathode metals
2. Sustainability & Circular Economy
- 95% process water reused
- 100% residue utilized in construction or pigment production
3. Economic Benefits
- 35% lower OPEX than conventional methods
- Additional revenue from premium Fe₂O₃ byproducts
Partner with PRS for Sustainable Metal Recovery
By applying our proven EPC capabilities and turnkey plant solutions, PRS helps mining and smelting operations transform waste liabilities into revenue streams—boosting sustainability and profitability.
