2.3 Resource development To date, more than 1600 phosphate deposits have been identified worldwide. Only a small part of the resources in these deposits have been determined and an even smaller part has been entered into the indicated and measured reserve category at prices in the range of 25 to 40 US$ per ton. At the current price levels in the range of 50 to 100 US$ per ton (see e.g. USGS, 2008), the reserve and reserve base substantially increase. Not only will sub-economic resources suddenly become exploitable but also a new category of phosphate reserves - the intermediate grade underground deposits - will become available. At present, 75% of the world’s phosphate rock is produced from open pit mining. Underground mining is only feasible from high or special grade reserves. However, with prices ranging from 50 to 100 US$/ton, underground mining will become economically much more attractive and will add to existing reserves. At a production cost of up to 90 US$ per ton the then available reserve base would be sufficient for 240 years’ consumption under a moderate consumption growth scenario (FAO/IFA, 1999). As a response to the recent price developments, phosphate exploration has already picked up. Both land-based and marine resources have become the subject of exploration activities and development studies. As an example, Oklo Uranium Ltd has been granted an 8000 km2 permit for exploration in Mali, covering its Tatteul Phosphate Project. The area contains some 185 km2 of contiguous outcrop of phosphate bearing sedimentary rock (shale). Grades vary from 18 to 31% P2O5 and a thickness ranging from 0.5 to 2.2 metres (Oklo Uranium Ltd., 2008). European phosphate deposits, such as the phosphatic chalk of the Mons Basin in Belgium and the Paris Basin in France – with grades in the order of 7 to 15% P2O5 - may also become of interest at higher prices. Attainable resources in Belgium are estimated at 60 Mt (Geochem Research, 1994). Also in Spain, substantial resources with P2O5 contents in the order of 13 - 19% are available in the Central Iberian Zone. Large resources are also available on the continental shelf and on sea mounts in the Atlantic and Pacific Oceans (phosphorite nodules). Although phosphate prices are still too low to mine phosphate in the deep oceans, resources on the continental shelves are currently being evaluated. For example, the Bonaparte Diamond Mines company is shifting towards the development of prospective marine phosphate deposits in Namibia. Although the project is currently at the sampling stage, plans are to mine 40 - 50 million tons of unconsolidated sediment with a grade of 10 - 25% P2O5 in order to produce 3 million tons of commercial 35% grade P2O5 per year (Burger, 2008). The total resource in the upper 10 cm of the sediments on the Namibian shelf is estimated at 3020 Mt of ore albeit of a much lower grade (Notholt et al., 2005). 17 Pagina 26

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