Metallurgical Accounting

Metal balance: feed → concentrate → tailings · Recovery curves · Reagent consumption

Total Feed

2.69Mt

Cu Conc

229kt

Zn Conc

188kt

Avg Cu Rec

85.6%

Avg Zn Rec

87.6%

No plant model linked. Configure Process Plant

Period	Feed t	Cu%	Zn%	Cu Conc	Cu Grd	Zn Conc	Zn Grd	Tail Cu	Tail Zn	Cu Rec	Zn Rec	Reag	P80	✕

Tailings Metal Loss Analysis

Cu $/t:

Zn $/t:

Au $/oz:

Ag $/oz:

Total Tails

2.28Mt

Cu Lost

10,028t

Zn Lost

13,690t

Au Lost

0oz

Ag Lost

0oz

Gross Value

$123.6M

Period	Tails t	Cu Lost t	Zn Lost t	Au Lost oz	Ag Lost oz	Cu Value	Zn Value	Au+Ag Value	Total $/period	Cumulative $
M1	171,999	344.9	1484.9	0	0	$2931k	$4158k	$0k	$7089k	$7.09M
M2	191,908	1025.7	1094.3	0	0	$8718k	$3064k	$0k	$11782k	$18.87M
M3	192,433	928.6	1058.7	0	0	$7893k	$2964k	$0k	$10857k	$29.73M
M4	176,468	1040.8	1653.4	0	0	$8846k	$4630k	$0k	$13476k	$43.20M
M5	172,527	846.7	1214.5	0	0	$7197k	$3401k	$0k	$10598k	$53.80M
M6	203,785	707.6	1490.1	0	0	$6015k	$4172k	$0k	$10187k	$63.99M
M7	209,444	1093.5	436.3	0	0	$9295k	$1222k	$0k	$10516k	$74.51M
M8	173,640	834.5	1187.6	0	0	$7094k	$3325k	$0k	$10419k	$84.92M
M9	214,193	412.5	1105.6	0	0	$3506k	$3096k	$0k	$6602k	$91.53M
M10	181,553	983.6	1427.6	0	0	$8360k	$3997k	$0k	$12358k	$103.88M
M11	216,332	922.9	1061.1	0	0	$7844k	$2971k	$0k	$10815k	$114.70M
M12	174,372	886.7	475.8	0	0	$7537k	$1332k	$0k	$8869k	$123.57M
TOTAL		10,028t	13,690t	0oz	0oz	$85.2M	$38.3M	$0.0M	$123.6M	$123.6M

Recovery Improvement Trade-Off

What-if: additional metal recovered per 1% improvement in recovery rate. Based on current feed grades and annual throughput.

+1% Cu Recovery

685t Cu

$5.82M/yr

+1% Zn Recovery

1095t Zn

$3.07M/yr

+1% Au Recovery

0oz Au

$0.00M/yr

+1% All Metals

$8.88M/yr

Justifies reagent/circuit optimization spend

Tailings Value Recovery Strategies

Industry-verified approaches for extracting additional value from tailings. References cited from peer-reviewed and industry sources.

1. Flotation Scavenging Circuit

Install scavenger flotation cells on final tails. Typically recovers additional 2-5% of contained Cu/Zn at marginal cost. Proven at Antamina (Peru), Mount Isa (Aus), and Kidd Creek (Canada).

Ref: Wills & Finch, Mineral Processing Technology, 8th Ed., Ch.12. | Typical CapEx: $2-8M depending on throughput.

2. Gravity Recovery (Gold)

Gravity concentrators (Knelson, Falcon) in grinding circuit recover free gold before flotation. 30-60% of gravity-recoverable gold typically captured. Standard at Newmont Boddington, AngloGold Obuasi.

Ref: Laplante, A.R. (2000), Testing Requirements for Gravity Gold Circuit Design, CIM Bulletin. | CapEx: $1-5M.

3. Tailings Reprocessing (Historical)

Retreatment of old tailings dams using modern flotation/leaching. DRDGold (SA) processes 500ktpm of Witwatersrand gold tailings. KCGM reprocesses tailings at Kalgoorlie Super Pit. Typically economic above 0.3g/t Au or 0.1% Cu.

Ref: Edraki et al. (2014), Designing Mine Tailings for Better Environmental Outcomes, J. Cleaner Production. | NPV depends on head grade and volume.

4. Bioleaching / Heap Leaching

Bacterial oxidation of sulfide tails to liberate locked metals. Used commercially for Cu (BHP Olympic Dam), Au (Fairview, Barberton). Lower CapEx than conventional milling but slower (months vs hours).

Ref: Watling, H.R. (2006), The Bioleaching of Sulphide Minerals, Hydrometallurgy 84(1-2). | Operating cost: $2-6/t tails.

5. Paste Tailings / Dry Stacking

Filtered tails reduce water loss (recover 85-95% process water) and create stable dry-stacked facility. Reduces TMF CapEx and closure liability. Adopted at Escobal (Guatemala), Rosemont (Arizona), Karara (Australia).

Ref: Jewell, R.J. & Fourie, A.B. (2015), Paste and Thickened Tailings: A Guide, ACG. | Water recovery value: $0.50-2.00/m3.

6. Critical Minerals Recovery

Extract cobalt, REE, scandium, indium, or germanium from polymetallic tails. Increasing economic viability due to EV/battery demand. USGS estimates billions in critical minerals locked in US mine tailings alone.

Ref: USGS (2022), Critical Mineral Resources of the United States. | Pre-feasibility study recommended before investment.

Disclaimer: Strategies listed are based on published industry practice. Economic viability depends on site-specific grade, mineralogy, tailings characteristics, and local regulations. Independent engineering assessment required before implementation.