Company: RTNTF
Filing Date: 2025-02-20
Form Type: 20-F
Source: 0001628280-25-006642
Chunk: 516

Company: RIO TINTO LTD
Filing Date: 2025-02-20
Form: 20-F
Chunk 516
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 riotinto.com |

Additional information | US Disclosure

geology models and changes to pit designs for various reasons. The Mineral Reserves estimates are based on the following assumptions: – Geological model – Orebody block models (OBMs) are developed for Mineral Resources reporting within each mining area and form the basis of the Mineral Reserves estimates. – Moisture – Geology models contain tonnage estimates on a dry in situ basis. During generation of the OBMs, the estimated water content (moisture) for each block model block is added. The moisture estimate includes consideration of material physical properties and hydrogeology. By including both dry tonnes and water content in the block models, estimates for dry and wet tonnages can be determined from the block models as required for planning, reporting or any other purpose. Metallurgical regressions are applied to dry material. From this, expected water content is predicted for each product, allowing reporting of wet product tonnes by combining the dry tonnes and moisture content. – Metallurgical and processing recoveries – Metallurgical and processing recovery estimates are applied to crusher feed tonnages based on the processing plant type. Dry crushing and screening plants achieve a recovery of 100%. Wet plants achieve typical recoveries of 85 to 92% (dry basis) for the Marra Mamba and Brockman ores. Processing of pisolite ores results in recoveries ranging from 50% to 90% due to the relatively higher and more variable clay content. The beneficiation plant yield is approximately 60% to 70%. – Cut-off – The key determinant for the classification of material into ore and waste is the target product specification of the various iron ore products. Whether a particular parcel of material has economic value or not does not depend on the characteristics of the parcel itself, but on its potential contribution to a material blend. Target product specifications determine the quantity of saleable ore that can be economically extracted from the orebodies, and thus the reported Mineral Reserves. The cut-off grade for the reported Mineral Reserves is not based on calculation of a break-even content of a payable mineral, or similar economic break-even analysis. The primary parameter for determining if material is ore or waste is iron content. Deleterious elements such as phosphorous or alumina can also influence the ore-waste determination. Iron cut-off grade ranges for the different material types can be seen below:

| Ore Type              | Cut-off Range (Fe%) |
| Yandicoogina Pisolite | 55%