South Deep Gold Mine Feasibility Study: $139M NPV Over a 85-Year Mine Life
Gold Fields Limited's South Deep Gold Mine in South Africa, Gauteng Province (Westonaria/Vanderbijlpark district, ~45 km southwest of Johannesburg) has a Feasibility Study outlining an after-tax NPV of $139M. The mine plan runs 85 years at about 11 t Au per year.
Gold Fields Limited's South Deep Gold Mine has reported Feasibility Study results for the gold project in South Africa, Gauteng Province (Westonaria/Vanderbijlpark district, ~45 km southwest of Johannesburg). The study headlines an after-tax net present value of $139M at a 10.8% discount rate. It reflects Gold Fields Limited's (GFI) latest disclosed economics for the asset.
Economics. The after-tax NPV is $139M using a 10.8% discount rate. Economics are based on Reserve/Mine plan: $1,500/oz Au (mineral reserves); Mineral resources: $1,725/oz Au.
Production and mine plan. The project envisions an underground (bulk mechanised, long-hole stoping with paste fill, destress mining) operation. Life of mine is 85 years. Average annual production is approximately 11 t Au. Average head grade is 5.0 g/t Au (total mineral reserves). Metallurgical recovery averages 96.5%.
Resources and ownership. The company holds a 90.245% interest in the project. Royalties and streams: Governmental royalty under South African Mineral and Petroleum Resources Royalty Act; maximum % royalty for refined product is 5%, unrefined 7%; royalty = gross sales value x formula percentage; operating and capital expenditure deductible for EBIT determination..
These figures are extracted from Gold Fields Limited's technical disclosures and reflect the most recent Feasibility Study on file. Compare this project against other developers and producers in our project economics database, and always verify the numbers against the original technical report before making any investment decision.
Reserves & Resources
| Category | Tonnage | Grade | Contained |
|---|---|---|---|
| Proven | 9,228 kt | 5.8 g/t Au | 1,714 koz Au |
| Probable | 165,945 kt | 4.9 g/t Au | 26,284 koz Au |
| Proven & Probable | 175,173 kt | 5.0 g/t Au | 27,998 koz Au |
| Category | Tonnage | Grade | Contained |
|---|---|---|---|
| Measured | 55,850 kt | 1.9 g/t Au | 3,364 koz Au |
| Indicated | 74,749 kt | 6.5 g/t Au | 15,682 koz Au |
| Measured & Indicated | 130,600 kt | 4.5 g/t Au | 19,046 koz Au |
| Inferred | 20,363 kt | 9.1 g/t Au | 5,958 koz Au |
| Measured (UG) | 14,403 kt | 6.6 g/t Au | 3,062 koz Au |
| Indicated (UG) | 74,749 kt | 6.5 g/t Au | 15,682 koz Au |
| Measured & Indicated (UG) | 89,152 kt | 6.5 g/t Au | 18,744 koz Au |
| Inferred (UG) | 20,363 kt | 9.1 g/t Au | 5,958 koz Au |
| Measured (Tailings/TSF) | 41,448 kt | 0.2 g/t Au | 302 koz Au |
| Measured & Indicated (Tailings/TSF) | 41,448 kt | 0.2 g/t Au | 302 koz Au |
Our Analysis
- NPV after-tax
- $139M
higher than 22% of 193 projects we track
- Mine life
- 85yrs
- Study price assumption
- Reserve/Mine plan: $1,500/oz Au (mineral reserves); Mineral resources: $1,725/oz Au
- Spot gold today
- $4,200.70/oz
An 85-year mine life is the defining fact here, and it is not a figure that flatters a headline: it says this is an operating asset with a reserve that will outlast most of the gold projects we track, and it means the investment case rests on sustained execution rather than on a single development window. That durability is the reason to look closer, not a reason to relax.
Against the 193 gold projects in our database, the after-tax NPV of $139M ranks higher than only 22% of them. Nothing here is an outlier, and the peer comparison is the honest framing: this is a mid-pack asset by value, in a portfolio of 15 projects we track for a company with a US$32.80B market cap. The NPV sits well below that market cap on a rough currency-adjusted basis, so this project is not what moves the equity. For an investor, the practical consequence is that the asset's returns are unlikely to be the swing factor in the share price, and the diversified portfolio means single-project risk is diluted in both directions.
The constraint that matters most is the price deck. The study assumes $1,500/oz for reserves and $1,725/oz for resources, against a live spot of $4,200.70/oz. That gap is wide enough that the economics as published are conservative relative to today's market, which cuts both ways: it leaves genuine upside if spot holds, but it also means the study's numbers were not built to test the current price environment. The feasibility-level estimate, with its plus or minus 15% band, carries the most weight of any study stage, and the flat comparison to the 2024 filing (NPV +0%, mine life +0%) tells you nothing has been re-engineered. The question that decides this project is whether the operation can hold its cost base through an 85-year life, because at this scale that, not the headline NPV, is what compounds.
Our take, benchmarked against the project economics in the Mining Stocks database. Figures are estimates drawn from company technical reports — not investment advice; always verify against the source filing.
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