Metallurgical Accounting

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

Total Feed

2.69Mt

Cu Conc

205kt

Zn Conc

184kt

Avg Cu Rec

85.5%

Avg Zn Rec

90.0%

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

2.30Mt

Cu Lost

8,823t

Zn Lost

10,985t

Au Lost

0oz

Ag Lost

0oz

Gross Value

$105.8M

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	170,240	676.3	1042.9	0	0	$5748k	$2920k	$0k	$8668k	$8.67M
M2	181,701	501.8	389.6	0	0	$4265k	$1091k	$0k	$5356k	$14.02M
M3	204,252	904.7	1110.1	0	0	$7690k	$3108k	$0k	$10798k	$24.82M
M4	191,748	494.4	774.4	0	0	$4203k	$2168k	$0k	$6371k	$31.19M
M5	200,031	812.0	1707.3	0	0	$6902k	$4780k	$0k	$11682k	$42.88M
M6	192,362	1006.0	590.7	0	0	$8551k	$1654k	$0k	$10205k	$53.08M
M7	187,604	1118.0	669.5	0	0	$9503k	$1875k	$0k	$11377k	$64.46M
M8	190,798	608.5	686.8	0	0	$5173k	$1923k	$0k	$7096k	$71.55M
M9	201,159	541.5	1236.5	0	0	$4603k	$3462k	$0k	$8065k	$79.62M
M10	195,802	865.1	1487.5	0	0	$7353k	$4165k	$0k	$11518k	$91.14M
M11	198,105	768.0	893.5	0	0	$6528k	$2502k	$0k	$9030k	$100.17M
M12	185,836	526.2	396.7	0	0	$4473k	$1111k	$0k	$5584k	$105.75M
TOTAL		8,823t	10,985t	0oz	0oz	$75.0M	$30.8M	$0.0M	$105.8M	$105.8M

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

606t Cu

$5.15M/yr

+1% Zn Recovery

1058t Zn

$2.96M/yr

+1% Au Recovery

0oz Au

$0.00M/yr

+1% All Metals

$8.11M/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.