Pyrite Catalyst Leaching Process for Chalcopyrite Passivation
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Solution Overview
Problem
Chalcopyrite mineral surfaces passivate in oxidizing solutions, limiting the rate of copper leaching due to the formation of a passivating film, and existing methods assume the anodic half-cell reaction is the rate-limiting step, whereas the cathodic half-cell reaction is actually slow.
Innovation Solution
Incorporating pyrite as a catalyst in the leaching process in an acidic sulphate solution, maintaining the pyrite in a substantially unoxidized state to facilitate ferric reduction and reduce passivation, allowing for copper extraction from copper sulphide-containing concentrates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If chalcopyrite is leached in oxidizing solutions, then copper extraction can be achieved, but the mineral surfaces become passivated and the leaching rate is limited
Solution Approach 1:
Pyrite is introduced as an intermediary substance that mediates the leaching process by providing an alternative surface for ferric reduction. The pyrite particles act as catalysts that facilitate the cathodic half-cell reaction without being consumed, thereby maintaining chalcopyrite surface reactivity and preventing passivation while enabling continuous copper extraction at higher rates
2Ease of manufacture
If the anodic half-cell reaction is assumed to be rate-limiting, then conventional leaching methods are used, but the actual rate-limiting cathodic reaction is not addressed
Solution Approach 1:
The invention changes the fundamental parameter being optimized by shifting focus from the anodic reaction (mineral breakdown) to the cathodic reaction (ferric reduction). By introducing pyrite and controlling solution potential to enhance ferric reduction kinetics, the process achieves higher leaching efficiency while maintaining operational simplicity through a straightforward modification of the leaching environment
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method achieves virtually complete copper extraction in as little as four hours, which is the shortest time recorded under atmospheric conditions without ultrafine grinding, by providing an alternative surface for ferric reduction and maintaining the solution potential below 500 mV vs Ag/AgCl.
Implementation Method 1
The present inventors have discovered that it is primarily the cathodic half-cell reaction (i.e., ferric reduction) that is slow on the chalcopyrite surface, and have determined that the presence of an alternative catalytic surface for ferric reduction in electrical contact with chalcopyrite provides a mechanism whereby the passivation of chalcopyrite can be eliminated
Implementation Method 2
the presence of an alternative catalytic surface for ferric reduction in electrical contact with chalcopyrite provides a mechanism whereby the passivation of chalcopyrite can be eliminated
Implementation Method 3
The process may include the application of an oxidizing agent, e.g. oxygen in the form of air or O2 gas
Data Source
AI summary
A method of leaching copper from copper sulphide-containing concentrates, such as chalcopyrite, includes using pyrite as a catalyst for ferric reduction in order to eliminate passivation of the chalcopyrite surface, the process being carried out under conditions whereby the pyrite is not materially oxidized, for example by maintaining the operating solution potential at a suitable level. The leaching is carried out in an acidic sulphate medium and may include oxidation by oxygen-containing gas. The leached copper is then recovered, for example by solvent extraction and electrowinning. The leaching process can result in the virtually complete extraction of copper at atmospheric pressure in as little as four hours.