Simandou Blocks 3 and 4 (SimFer): an iron ore operation in Guinea

Simandou Blocks 3 and 4 (SimFer) is an open-pit mine producing iron ore in Nzerekore Region, Republic of Guinea, operated by SimFer S.A.. The sources report 2,271 thousand tonnes ('000 t), crushed ore at the mine gate in wet metric tonnes for CY2025; the basis is 100% of the Simandou mine, as reported by Rio Tinto (Total column). The sources do not give a whole-operation figure in usable ore that can be compared with world output, so no share is computed.

Who owns and operates it?

Owners of Simandou Blocks 3 and 4 (SimFer)
Owner	Interest	As of
Rio Tinto Indirect interest: Rio Tinto holds 53% of SimFer Jersey Limited, which owns 85% of SimFer S.A. (the mine company); Rio Tinto prints its equity share of production as 45.0%.	45%	31 December 2025
CIOH (Chinalco-led joint venture) CIOH, a Chinalco-led joint venture, holds 47% of SimFer Jersey Limited, the holding company through which Rio Tinto and CIOH own 85% of SimFer S.A.; its interest in the mine is not printed as a percentage.	—	31 December 2025
Republic of Guinea The Republic of Guinea holds 15% of SimFer S.A.	15%	31 December 2025

Interests are as stated in the sources below on the date shown. Ownership changes with deals, so a stake may have changed since the date shown.

How much does it produce?

Reported output of Simandou Blocks 3 and 4 (SimFer)
Period	Output	Basis	Where in the source
CY2025	2,271 thousand tonnes ('000 t), crushed ore at the mine gate in wet metric tonnes Simandou production is crushed ore at the mine gate; final crushing is outside the figure. It is not the saleable production measure used for the other iron ore rows.	100% of the Simandou mine, as reported by Rio Tinto (Total column)	PDF p.279 (printed p.277), 'Metals and minerals production' table, IRON ORE ('000 tonnes), row 'Simandou iron ore production (000 tonnes)', 2025 Total column; production data notes 8 and 10 · Rio Tinto
CY2025	1,023 thousand tonnes ('000 t), crushed ore at the mine gate in wet metric tonnes	Rio Tinto share (45.0%)	PDF p.279 (printed p.277), 'Metals and minerals production' table, IRON ORE ('000 tonnes), row 'Simandou iron ore production (000 tonnes)', 2025 Rio Tinto share column · Rio Tinto

Between CY2025 and CY2025 the reported figure rose by 122.0%, in the same unit and on the same basis.

Status: ramping, as of 31 December 2025.

Rio Tinto says the Simandou figure represents crushed ore at the mine gate, excludes final crushing, and is not saleable production as defined for its other iron ore rows (note 8).
Rio Tinto says the rail and port infrastructure co-developed for the SimFer concession also serves Simandou Blocks 1 and 2, which are independently owned by the Winning Consortium Simandou; its report prints no production figure for Blocks 1 and 2.
The figure is crushed ore at the mine gate, not saleable product, so no share of world output is computed.

How does it compare?

Other iron ore operations on this site: Hamersley mines (Rio Tinto Pilbara), Hope Downs (Rio Tinto and Hancock Prospecting), Robe River - Robe Valley, Robe River - West Angelas, Iron Ore Company of Canada (IOC), Western Australia Iron Ore (WAIO), Fortescue Pilbara hematite operations, Iron Bridge (magnetite), Onslow Iron, Serra Sul (S11D), Carajas, Serra Norte, Carajas, Itabira complex. See where iron ore comes from for the country totals, the country page for Guinea.

Sources

Rio Tinto: Annual Report 2025 (annual report (furnished to the SEC on Form 6-K, February 2026), CY2025 with 2024 and 2023 comparatives). Opened 4 November 2026; used: PDF pp.33, 160, 271, 279, 317-320 (printed pp.31, 158, 269, 277, 315-318); also PDF p.338 (listing).
U.S. Geological Survey: Mineral Commodity Summaries 2026: Iron Ore (government statistical summary, 2025 (world and country mine production of usable ore)). Opened 3 November 2026; used: world and country mine production table, usable ore.

Method and limits

Reported, not estimated. Output is the figure the operator or owner published, in the unit it used. This site does not estimate output where none is published.
Shares. A share divides output in usable ore by the USGS world or country total for 2025. Where the operator's year is a fiscal year or the unit is a concentrate or a carbonate equivalent, the share is approximate or not given.
What is compared. Operators print tonnes of ore: saleable production for most, run-of-mine and pelletizing feed for Vale, and shipments for Fortescue and Onslow Iron, mostly as wet tonnes. The figure is compared with the USGS usable-ore total, which does not state a moisture basis, so the share is indicative.
Whole operation or owner's share. The basis column says which. A joint venture's output is never counted twice.
Partial list. Only operations with a published figure are listed, so the rank is among those on this site, not among every iron ore mine. Shares of a country's output mix periods and bases, so treat them as indicative.
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