Cadmium and Other Minor Elements in World Resources of Phosphate Rock

Keywords: Phosphate rock composition, World P production, World P reserves, Potentially hazardous elements, Cadmium.

Literature sources and in-house analyses at the International Fertilizer Development Center (IFDC) were used to compile a worldwide data base on the levels of arsenic (As), cadmium (Cd), chromium (Cr), lead (Pb), mercury (Hg), selenium (Se), uranium (U), and vanadium (V) that are found in igneous and sedimentary phosphate rocks. When compared with an average shale, the most common sedimentary rock, sedimentary phosphate rocks are enriched in As, Cd, Se, and U. When compared with the average compositions of granites and basalts, igneous phosphate rocks are also considered enriched in As, Cd, Se, and U. The average contents of Cd, Cr, Hg, V, and U in sedimentary phosphate rocks are significantly higher than those in igneous phosphate rocks.

World production of phosphate rock is dominated by 12 countries. Approximately 13% of current world production is from igneous sources and 87% is from sedimentary sources. Sedimentary phosphate rock will continue to supply the bulk of global phosphate needs in the future. In the medium-term future (10-15 years), reserves of low cadmium phosphate rock in central Florida will be depleted, and production will be reduced. Production to meet global needs will come from other deposits, which in general may have higher contents of cadmium and other minor elements.

S J Van Kauwenbergh, IFDC, Muscle Shoals, Alabama, USA.

40 pages, 2 figures, 7 tables, 45 refs.