Copper: the heap leach–SX–electrowin family

The hydrometallurgical copper route is the canonical leach–SX–electrowin flowsheet, and it composes from mechanisms taught earlier. This page assembles them into the circuit that recovers copper cathode from low-grade ore — naming each mechanism and what it contributes, not teaching it again.

The flowsheet in one line

Leach the copper out of crushed ore stacked on a pad, upgrade and purify the dilute solution by solvent extraction, and electrowin it to cathode: heap leach–SX–EW. The combination that made low-grade copper oxide ores economic.

What each stage is doing

The leach is heap leaching with dilute sulfuric acid — the percolation family of topic 4.4 — irrigating an ore stack and collecting a pregnant leach solution, with the acid demand set by the gangue mineralogy of topic 4.7. Solvent extraction is topic 6.6: an organic extractant pulls the copper out of the dilute, impure leach solution into the organic, then a strip stage with strong acid returns it to a clean, concentrated electrolyte — selectivity in at extraction, concentration out at strip, set by the O/A ratio. Electrowinning is topic 7.1: the clean copper electrolyte is plated to cathode at a current efficiency and a power draw that are the tankhouse’s running cost.

The defining numbers

The acid consumption of the heap — reagent per tonne of ore, set by the acid-consuming gangue — lands on the leach reagent consumption calculator below. The electrowinning step is read on the electrical-power relation P = V × I (topic 7.1) and on the copper sulfate hub for the electrolyte’s property data. The SX stage itself is read on the O/A ratio and the McCabe-Thiele staircase rather than a single committed calculation.

The concentrate (POX) variant

Heap leach–SX–EW handles oxide and secondary sulfide ores. A sulfide concentrate that will not leach at atmospheric conditions takes the pressure oxidation route instead: the autoclave of topics 3.3 and 4.6 oxidises the sulfides under temperature and pressure to put the copper into solution, after which the same SX–EW back end recovers it. The leach changes; the recovery train does not.

Where it differs from the others

Copper is the workhorse of solvent extraction, where gold uses adsorption and cementation. Its lixiviant is acid sulfate, not alkaline cyanide; its front end is most often a heap rather than a tank; and its product is electrowon cathode directly from a purified electrolyte. The same SX–EW back end recurs in nickel, cobalt and uranium, which is why copper is the family to learn it on.