*This is an abstract only. No full paper is available for
Yandi iron ore mine, located 135 km north of Newman in the Pilbara region of Western Australia is a channel iron deposit (CID) within the Marillana palaeochannel network. The CID ore is broadly classified as upper CID (UCID) and lower CID (LCID), based on their stratigraphic position in the channel. The UCID – characterised by hematite-goethite granules, is hard, competent and contains less moisture; contrasted with LCID – characterised by goethite-limonite, is soft and friable in nature.
Increased LCID feed to plants, due to depleting UCID sources, presents the risk of material handling problems and reduced productivity due to high clay and moisture content.
Work has been done to quantify the cut-off point when material will likely cause blockages in the ore handling plants at Yandi. The algorithm used to calculate the material ‘handle-ability’ is derived from analysis of different samples – with different material handling properties – collected from different pits and also, our current cut-offs of AL2O3, TIO2 and P. The algorithm has been described as:
Clay Index = 100 000*(P-0.06)+10 000*(TiO2–0.1)+1000*(Al2O3)
A resulting positive clay index number indicates clay-rich material, whereas material with a large negative clay index indicates non-clay-rich material. However, materials with a clay index number, positive or negative, close to zero, need to be checked in the pit for presence of clay.
The clay index is calculated at blast cone level and informs the design of a grade control model. Regions where pervasive clay material has been identified, are mapped and blocked out to segregate from material with better handling qualities. This has, in turn, enabled better planning around controlling the proportion of feeding both problematic material and material with better handling properties, thereby extending the life of Yandi mine.
Riedel, J and Ting, A, 2017. Material handling – mitigating
handling issues with clay index, in Proceedings Tenth International Mining
Geology Conference 2017, pp 355–356 (The Australasian Institute of Mining and