Traditional processing of copper sulphide ore bodies utilises flotation to produce a saleable copper-rich sulphide concentrate. Cyprium’s management team has developed unique intellectual property relating to sulphide heap leach processing methodology, an atypical alternative method to economically extract copper from sulphide ores. Due to its reduced capital and operating cost profile, a heap leach approach can often unlock value in stranded projects and/or projects with problematic mineralogy, lack of scale, lower than average head grades and/or projects in challenging locations.
Other advantages of sulphide heap leach processing methodology include the minimisation of environmental impacts, production of a final LME Grade A cathode onsite, no further downstream processing and higher realised sales proceeds.
Sulphide Heap Leach Process
Conceptually, sulphide heap leach is a straightforward process that has many competitive advantages over the traditional onsite copper in concentrate production methods, including:
- Sulphide leaching is exothermic, generating its own heat to facilitate leaching of copper
- Air, ground water, acid and electricity are the primary inputs, together with a limited number of other reagents required in the process, which reduces production and maintenance costs
- Acid that leaches the copper is self-generated in the sulphide heaps, reducing operating costs
- Closed circuit process cycle with the raffinate solution, after the extraction of copper, being returned to the heap leach pads to resume the leaching copper into solution
- Reduced size for processing plant and no requirement for tailings dams to store waste materials from a concentrator, decreasing development costs and environmental impacts
- Transport costs are reduced due to less materials being shipped to and from the mine site
- No downstream treatment and refining charge deductions from sales revenue
- Government royalty rates levied on copper in concentrate being up to double than for cathode
The leached copper in solution is then processed by solvent extraction-electrowinning (SX-EW) to produce LME grade A cathode, which has a copper purity of more than 99.99%. All of the LME grade A copper cathode produced onsite is sold at a premium in liquid global markets whereas for concentrate, sales proceeds are normally based on 96.5% of the copper contained in the concentrate, downstream treatment and refining charges are also deducted along with penalty charges for other contaminates contained the concentrate.