Company: RTNTF
Filing Date: 2025-02-20
Form Type: 20-F
Source: 0001628280-25-006642
Chunk: 523

Company: RIO TINTO LTD
Filing Date: 2025-02-20
Form: 20-F
Chunk 523
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 resource definition activities are ongoing to upgrade Mineral Resources understanding to support the mine plans and to develop Mineral Reserves. These activities include drilling and in-pit mapping. Geological understanding of the two deposits is supported by a total of approximately 2,732km of drilling undertaken in a total of approximately 8,740 drill holes. Surface mining is by drilling and blasting along with shovel/excavator loading and truck haulage from each of the two open pits. Extracted sulphide ore undergoes crushing prior to processing in one of three concentrators with concentrate piped to the Coloso port for drying. Lower grade sulphide ore is directly dumped onto leach pads and is processed by biological leaching. Oxide and transitional ores are processed using heap leaching. Leached products are converted to copper cathode then railed to Antofagasta port.

| Annual Report on Form 20-F 2024 | 348 | riotinto.com |

Additional information | US Disclosure Age modernisation and condition of the equipment and facilities The infrastructure, equipment and facilities within Escondida are of variable age. Construction commenced at Escondida in 1998 with first production in 1990. A number of expansion phases followed from 1993 onwards which included the development of additional infrastructure to increase production. Key milestones subsequent to first production in 1990 relating to the development of the operations were: – 1998 Acid heap leaching of oxides commenced – 2002 Second concentrator (Phase 4) inaugurated – 2005 Mining commenced at the Escondida Norte deposit – 2006 Dump bio-leaching of sulphides commenced – 2007 First desalination plant commenced pumping – 2016 Third concentrator inaugurated – 2017 Second desalination plant commenced pumping – 2020 Operation converted to 100% use of desalination water MEL undertakes planned maintenance programs at Escondida and implements scheduled replacements of mine fleet and infrastructure components that are intended to maintain continued reliable operation of equipment, facilities and infrastructure to meet operational requirements. Book value For the book value for Escondida, see Rio Tinto Financial Information by Business Unit on pages 266 - 267 . Geology and mineralisation The Escondida deposit and Escondida Norte copper deposit lie in the Escondida-Sierra de Varas shear lens of the Domeyko Fault System. The deposits are supergene- enriched copper porphyries with primary sulphide mineralisation associated with multiple phase intrusions of monzonite