Ann: Maiden Resource at Winmar Deposit Hamersley , page-12

re: Ann: Maiden Resource at Winmar Deposit Ha... "The CID deposits relative lack of consolidation and proximity close to the surface in most cases renders them liable to bulk mining with little or no need for drilling and blasting. This then is a significant cost saving to miners, who can offset a lower revenue from Fe percentages in the ore via the ease of extraction"

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Channel iron deposits are an important source of iron ore, with the deposits at Yandi and Robe River accounting for approximately 47% of iron ore mined from the Hamerley Iron province.

Although channel iron deposits are typically low-grade at 53% to 57% Fe in-situ, they are composed of goethite-limonite which are hydrated iron oxide species. Ore typically contains around 8% to 12% water, and <5% SiO2, and <3% Al2O3. The hydrous iron oxides can be calcined, and the CID ore on a volatile-free basis is around 63% Fe or more.

The CID deposits relative lack of consolidation and proximity close to the surface in most cases renders them liable to bulk mining with little or no need for drilling and blasting. This then is a significant cost saving to miners, who can offset a lower revenue from Fe percentages in the ore via the ease of extraction. Also, in most cases, beneficiation can increase the in-situ iron grade several percent by washing out the majority of clay, carbonate and hydrous limonite cements.

The key economic criteria for channel iron deposits are, firstly tonnage and location relative to infrastructure similar to other bulk commodities. Thereafter, the nature of the cement is important, particularly in the cases of carbonate cements containing magnesite, as magnesium is a problem. Rare channel iron deposits are rendered uneconomic because of a silica cement proving too durable for easy mining and crushing. The water content of channel iron deposits (quoted as Loss on Ignition) is from 7% to 12%, which is the highest of all iron ore types, generally due to the presence of goethite-limonite. Phosphorus, aluminium and sulfur levels are another concern, typically being above normal levels in-situ although if the phosphorus and aluminium are hosted in a weak cement, they can often be washed out during beneficiation. Most channel irons are upgraded via washing of the pisolite gravels to remove the cements and matrix.