Co-processing Copper Sulphide and Nickel Laterite Ore
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Solution Overview
Problem
Current hydrometallurgical processes face challenges in efficiently recovering copper, nickel, and cobalt from low-grade copper sulphide concentrates and nickel laterite ores, due to issues such as passivation of sulphide surfaces, high sulphuric acid concentrations, and the presence of impurities like arsenic.
Innovation Solution
A process that co-processes a copper-containing sulphide concentrate and a nickel laterite ore in a single pressure leaching step, using oxygen to generate sulphuric acid and heat, allowing for the simultaneous recovery of copper, nickel, and cobalt as salable precipitates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If hydrometallurgical leaching is used to extract copper from low-grade copper sulphide concentrates, then copper recovery is possible, but passivation of sulphide surfaces occurs limiting extraction efficiency
Solution Approach 1:
The patent applies parameter changes by conducting leaching at elevated temperatures (200-250°C) and pressures to alter the physical and chemical state of the sulphide surfaces. This prevents passivation by maintaining the sulphide surfaces in a reactive state, thereby enabling efficient copper extraction from low-grade concentrates without the limitations of ambient temperature leaching
Solution Approach 2:
The patent uses strong oxidizing conditions through the addition of oxygen and operation at elevated temperatures to accelerate the oxidation of sulphide surfaces. This prevents the formation of passive sulphur layers that would otherwise inhibit copper dissolution, enabling effective leaching of low-grade concentrates
2Speed
If leaching is conducted at higher temperatures to overcome passivation, then copper leaching rate increases, but sulphuric acid concentration becomes excessively high limiting copper recovery
Solution Approach 1:
The patent converts the harmful effect of high sulphuric acid concentration into a beneficial outcome by using the generated acid to leach nickel laterite ore simultaneously in the same autoclave. The acid that would otherwise limit copper recovery is utilized to extract nickel and cobalt from laterite, turning a process limitation into a dual-function advantage
Solution Approach 2:
The patent merges two separate processing operations into a single autoclave system: copper sulphide leaching and nickel laterite leaching. By combining these processes, the sulphuric acid generated from sulphide oxidation is immediately consumed by the laterite leaching reaction, maintaining acid balance and enabling high leaching rates without acid accumulation
3Object-generated harmful factors
If pressure leach solution is added directly to heap leach to neutralize acid, then acid values are neutralized, but water balance control becomes difficult
Solution Approach 1:
The patent extracts copper from the pressure leach solution through solvent extraction before adding the solution to the heap leach. This removal of copper prevents precipitation and loss in the heap, while the acid neutralization occurs through controlled interaction with heap materials, maintaining water balance
4Loss of substance
If copper is removed from pressure leach solution before adding to heap, then copper loss is prevented, but additional processing steps are required
Solution Approach 1:
The patent implements continuous solvent extraction to remove copper from the pressure leach solution in an uninterrupted process. This continuous operation efficiently prevents copper loss while integrating seamlessly with the heap leach process, avoiding the need for batch processing or complex intermittent operations
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 process achieves high extractions of copper, nickel, and cobalt (>95%), while minimizing the environmental stability issues associated with arsenic and reducing the need for external sulphuric acid, thus enhancing operational efficiency and reducing costs.
Implementation Method 1
a feed of the copper-containing sulphide concentrate and the introduced oxygen are controlled to produce sulphuric acid
Implementation Method 2
to produce heat to heat the incoming feeds to a temperature in the pressure vessel above 230° C.
Implementation Method 3
produce sulphuric acid to leach nickel, cobalt, copper and acid soluble impurities into a liquid phase
Implementation Method 4
to precipitate iron compounds and a majority of the arsenic, antimony and bismuth as solids
Data Source
AI summary
A process to recover nickel, cobalt and copper by co-processing copper-containing sulphide concentrate feed containing one or more of arsenic, antimony, and bismuth, and laterite ore feed containing nickel and cobalt by pressure oxidative leaching. The sulphide concentrate and oxygen are controlled to produce sulphuric acid to leach nickel, cobalt, copper and acid soluble impurities into a liquid phase of an acidic leach slurry, to precipitate iron compounds and a majority of the arsenic, antimony and bismuth as solids, and to produce heat to heat the incoming feeds to a temperature above 230° C. Reacted slurry is withdrawn, solids are separated, and the PLS solution contains the nickel, cobalt, copper and acid soluble impurities. A first solution purification stage on the PLS neutralizes free acid, precipitates one or more of iron, aluminum, chromium and silicon, and, separates as solids, the precipitated impurities and other solids from a first purified solution. Copper is separated from the first purified solution with a solvent extraction step to produce a raffinate solution reduced in copper and a copper loaded organic phase. The organic phase is stripped and copper is recovered with electrowinning. A second solution purification stage is conducted on the raffinate by one or both of neutralizing free acid and precipitating one or more of iron, aluminum, chromium and silicon, followed by separating as solids, the precipitated impurities and other solids from a second purified solution. Nickel and cobalt are recovered as mixed hydroxides or mixed sulphides from the second purified solution.