Traditional copper sulphide ores (such as chalcopyrite, bornite and chalcocite) are typically processed through mineral processing to produce copper sulphide concentrates with a copper grade of over 20 per cent. These concentrates are then sold to large smelters, where they are smelted in flash smelters, side-blown smelters or bottom-blown smelters to produce matte, which is subsequently refined through roasting and electrolytic refining to produce cathode copper.
However, with policy changes in many countries worldwide, restrictions on copper concentrate exports are gradually tightening. Resource-rich nations are increasingly inclined to promote local smelting and value-added processing to enhance value, create jobs and strengthen the industrial chain.
At this background, Metalcess proposes a localised smelting solution combining Pressure Oxidation Leaching (POL) and SX-EW for small-scale sulphide copper concentrates, enabling a green, closed-loop conversion from concentrate to cathode copper.
I. Oxygen-Pressure Leaching Process: The Key Pathway to Replacing Pyrometallurgical Smelting
For small- to medium-scale copper sulphide concentrates, the oxygen-pressure leaching process enables the efficient conversion of copper within a sealed, high-pressure system.
✔ Core Principles of the Process
In a high-temperature, high-pressure, oxygen-enriched environment:
• Copper sulphide minerals are rapidly oxidised and decomposed
• Copper enters the acidic leaching solution system
• Impurities such as iron form stable precipitates or are effectively separated
• Sulphur is selectively retained as elemental sulphur
✔ Key Advantages of the Process
• Replaces capital-intensive pyrometallurgical systems (flash furnaces/smelters)
• Suitable for on-site processing of small- to medium-scale copper concentrates
• Significantly reduces SO₂ emissions (environmentally friendly)
• Shorter process duration and faster construction cycle
II. Sulphur Resource Recovery: From Pollutant to Valuable By-product
One of the key advantages of oxygen-pressure leaching is the controlled recovery and utilisation of sulphur.
By precisely controlling the partial pressure of oxygen and reaction conditions:
• Complete oxidation of sulphur to SO₂ gas is prevented
• Sulphur is precipitated in the form of elemental sulphur (S⁰)
• It can be recovered via a solid–liquid separation system
The recovered sulphur product can be:
• Sold directly to the chemical market
• Used in the production of sulphuric acid and agricultural chemicals
• Reduce the environmental impact of the overall smelting system
This achieves a “copper + sulphur” dual-resource recovery model.
III. Leachate Purification + Solvent Extraction (SX) System: A Key Stage in the Rigorous Control of Impurities
The copper-rich solution produced by oxygen-pressurised leaching enters the solvent extraction system for selective separation.
✔ Core Functions of the SX System
• Highly selective extraction of copper from complex leachate
• Effective prevention of impurities such as iron, arsenic and lead from entering the electrowinning system
• Stabilisation of electrolyte purity and system equilibrium
✔ Engineering Capabilities Cover
• Design of primary pump-mix tanks
• Optimised design of secondary agitation and mixing tanks
• Design of multi-stage counter-current extraction processes
• Engineering design of clarification tanks and phase separation systems
• Organic phase loss control and recovery systems
The SX system ensures that the solution entering the EW system possesses:
• High concentrations of pure copper ions
• Extremely low impurity levels
• Stable electrochemical performance
IV. Electrowinning System (EW): Direct Production of High-Purity Cathode Copper
In the SX-EW closed-loop system, Metalcess provides a complete EPC design for the electrowinning plant:
• Electrolyser system design and layout
• Optimisation of current density and energy consumption
• Control of cathode copper crystal structure
• Electrolyte circulation and temperature control systems
• Automatic sheet stripping and cathode processing systems
The final products are:
• 99.99% LME Grade A cathode copper
• Products characterised by high consistency, high purity and high market acceptance
V. Metalcess’s EPC Turnkey Contracting Capabilities
As an EPC contractor specialising in hydrometallurgical engineering, Metalcess provides comprehensive process chain solutions:
✔ Process package capabilities
• End-to-end design of oxygen-pressure leaching + SX + EW
• Modular process configurations for small-scale concentrates
✔ Core Equipment Design Capabilities
• Engineering design of pressure leaching systems
• Design and manufacture of SX mixing and clarification systems
• Comprehensive engineering design of electrowinning systems
✔ EPC Delivery Capabilities
• Delivery of localised smelting projects overseas
• Construction of small- to medium-scale copper concentrate processing plants
• Process commissioning and support for achieving full production capacity
VI. Applicable Project Scenarios
This solution is particularly suitable for:
• Small-scale copper sulphide concentrate producers
• Countries and regions subject to restrictions on copper concentrate exports
• Projects driven by local smelting policies in resource-rich countries
• Small and medium-sized copper mine development projects
• Green upgrade projects requiring an alternative to pyrometallurgical processing
