Continental Shelf Phosphates-One Answer to Future Needs
Authors: Bowen Richard L. 
Published: October 2008

Predictions based on population growth and intensified use of phosphates in agriculture indicate phosphate consumption will quintuple by 2000 A.D. Several major nations, with offshore shelves, that are important foodstuffs producers, and a number of smaller ones, however, lack internal phosphate supplies for their agriculture. For many of these, the marine geology of the adjacent continental shelves suggests that economically recuperable phosphate deposits may occur thereon.

Minable phosphates may develop on shelves from accumulation of phosphate nodules (i.e., California) or from beneficiation by geologic processes from phosphate-bearing deposits of former lower grade. The many 100-20Om fluctuations of sea-level, with the accompanying weathering and lateral migrations of wave and strong current action, of the past million years have produced gold, diamond, tin, and gravel placers; the same processes apply to phosphate beneficiation and concentration. Especially where shelves are wide uneconomic phosphatic beds are known inshore, and coastal climates are relatively arid, high probability of minable offshore phosphate exists. Moreover, recent technological developments provide a low cost system of defining phosphate deposit outlines on shelves which geologic analyses indicate potentially favorable for phosphate exploration.

INTRODUCTION

Both the urbanization and the high standards of living of the world1s advanced nations result largely from the widespread introduction and utilization of phosphates into agriculture during the twentieth century. From a negligible production at the beginning of the century, demand for calcium phosphate grew to an annual 60 million metric tons in 1968, as food production in regions of advanced farming practices rose exponentially. Although mechanization and other improvements in agriculture account for a large portion of the vast growth in per capita production of each farmer, these changes have had their effects multiplied by the effective use of phosphate-based fertilizers, pesticides, and fungicides. Moreover, to meet the demands for improved nutrition and population growth, a world annual demand of around 300 million metric tons of phosphate is predicted for the year 2000 A.D. (Lewis, 1970). Now, 3/4ths of all phosphate mined goes into fertilizer, and the remainder into detergents, industrial and agricultural chemicals, pharmaceuticals, and other purposes; similar consumption is expected for the year 2000.

Phosphates now receive the blasts of ecologists and environmentalists as pollutants of streams and lakes, and even as health hazards. Thus, in the near future we expect improved sewage treatment methods to begin, at least in the advanced nations, to recover significant quantities of phosphates that can be reutilized while downstream water quality is improved. However, much of the phosphate used as fertilizers eventually will return to the sea in solution, and certainly this will continue to apply in the less advanced nations.

It seems likely, therefore, that the overwhelming bulk of the growing phosphate production required in coming years must come both from enlarging output from existing mining operations and from deposits yet to be found and developed. As phosphate falls into the category of bulk commodities, and the economics of transportation playa large part in the costs to the phosphate consumer, many nations in the years to come will undoubtedly wish to seek supplies of phosphate closer at hand.