regarding future price developments, some of the sub-economic reserves are included in the reserve base. Table 2.1 presents a schematic overview of the various categories of reserves and resources. Discovered resources Measured Indicated Inferred Undiscovered resources Table 2.1: Scheme of reserve and resource definition in the mining industry. The shaded area represents the reserve base. 15 Economic Marginally Economic Sub-economic Other Reserves Marginal Reserves Hypothetical and speculative Un-economic and non-conventional resources All categories together are called the resource of an ore or mineable substance. Obviously this resource is a highly flexible quantity that is – like the reserve base – defined mostly by the economic situation of the moment. For example, phosphate from non-conventional resources such as waste water may become economically feasible at price levels of US$ per ton. Current phosphate reserves Since phosphate rock is the only primary source of phosphate in the world and since no significant phosphate stocks are kept, the production and reserve figures of phosphate rock give a fair impression of the phosphate reserve situation in the world and its consumption. World reserves of phosphate rock, i.e. measured reserves were estimated at 15000 Mt in 2008 with a reserve base of 47000 Mt of phosphate rock (USGS, 2009). Roughly 80% of the phosphate rock reserves are accounted for by sedimentary phosphates. The remainder consists of igneous phosphates. The reserves of guano type deposits are negligible. As can be seen in Table 2.2, China, Morocco and the US are by far the largest producers of phosphate rock. Both the US and China consume all or most of their own domestic production, which makes Morocco the chief exporter of phosphate rock and phosphate products in the world. The main producers of igneous phosphates are Russia, South Africa, Finland, Brazil and Canada. Together with mine production, both the reserves and the reserve base of phosphate rock have increased over the past 15 years (Figure 2.1). After fluctuating between 125 and 145 Mt until 2006, mine production increased again to 167 Mt in 2008. Over the same period, reserves of phosphate rock increased from 11000 Mt to 18000 Mt in 2006 and then recently dropped to 15000 Mt. The reserve base increased from 34000 Mt to 50000 Mt and then dropped to 47000 Mt (Figure 2.1). The recent increase in phosphate prices, which is reviewed in Chapter 3, has not yet resulted in an increased reserve and reserve base. This is because these reserves depend on long-term price developments and not so much on spot prices. Moreover, evaluation of new reserves Pagina 24

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