ROI Calculator · Heap Leach

Oxygen is a reactant.
Is your circuit starved of it?

The Elsner equation puts oxygen on the left-hand side: 4 Au + 8 CN⁻ + O₂ + 2 H₂O. The mass optimum sits near six parts cyanide to one of oxygen, and a typical barren solution runs sixteen to thirty-three — badly oxygen-starved. That gap is the opportunity, and it closes: reach the optimum and cyanide becomes the limit, at which point more oxygen buys nothing at all. This model finds where you sit on that curve, caps the recovery gain by what is kinetically rather than mineralogically locked, and returns exactly zero when your circuit is not oxygen-limited.

Live — nothing to submit Leach chemistry, not flotation Returns zero when oxygen is not the limit Indicative pricing
01

The operation

Solution flow comes from the pad area actually under leach and your application rate — and the oxygen duty then follows from that flow, never the other way round. Asking for an oxygen rate independently of the water carrying it is how these models end up implying transfer concentrations that water cannot hold.

t/yr
g/t
%
days
L/h/m²
Contained metal
Recovered today
Left in the heap
Solution flow
02

Is oxygen actually limiting you?

This is the question the rest of the page depends on. For a cyanide circuit it is settled by the ratio of free cyanide to dissolved oxygen against the optimum near 6:1. For a copper sulfide heap it is not a solution concentration at all but how much of the ore column your air is actually reaching. If the answer is that oxygen is not your limit, this page will tell you so and stop.

mg/L
mg/L
mg/L
of volume
of contained
of the loss

Where oxygen stops helping
Dissolved oxygen after treatment
Leach rate
Recovery
Leach cycle
03

What the extra metal is worth

Credited net of what it costs to finish — incremental adsorption, elution and refining on a gold circuit, solvent extraction and electrowinning on copper — and adjusted for payable terms. Never at the gross metal price.

$/oz
$/oz
%
kg/t
$/kg
$/kWh
Net value per unit
Annual reagent bill
Gross margin on recovered metal
04

The system, and what it costs

The injector goes inline on the barren or raffinate line and the oxygenated solution reaches the pad through the drip network already there. The raffinate pumps already run, so the only new energy cost is the injector pressure drop — not a whole new circulation duty.

psi
m
% of equipment
Oxygen duty
Injector
Oxygen plant
Plant draw
Added pumping
$
$

Equipment
Installation
Indicative installed cost
Oxygen plant energy
Added pumping energy
Service & consumables
Annual operating cost
05

Value levers

Two of the three have no slider. Recovery and cycle time are derived from how far below its optimum your circuit is running — that is the entire point of the page, and a slider would replace the chemistry with a wish.

Gross annual benefit
Energy & service
Net annual benefit
06

Sensitivity

What actually moves the answer. On a heap of any size the equipment is a rounding error against the orebody, so payback is not the interesting number here — the interesting number is whether the recovery gain is real at all.

years
%
% of steady state

What moves the answer

Value across kinetic share and metal price

What has to be true
07

Take it with you

A one-page analysis for a metallurgist, a mine manager or a board — with the chemistry, the caps, the provenance of every figure and the pricing caveat attached.

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