Phosphate Mining in Florida
 |
The area in Central Florida where phosphate is found is known as Bone Valley because deposits often contain fossils of prehistoric creatures including mastodons, saber-tooth tigers and teeth from 40-foot sharks. Phosphate deposits in Florida are among the richest and most accessible in the world. Although there are several theories about how the deposits were formed, many experts believe the ocean covered what is now Florida about 10 million years ago. |
 |
Phosphate ore is found from 15 to 50 feet below the ground, generally in equal parts of sand, clay and phosphate rock. Draglines - or huge cranes that could easily hold several full-sized cars - remove the top layer of soil, and scoop up the phosphate matrix. The matrix is put in a pit where high-pressure water guns create a slurry that can be pumped to a processing plant. |
 |
The "beneficiation" process separates the sand and clay from the phosphate rock. After the largest particles are removed, the slurry is run through a hydrocyclone that uses centrifugal force to remove the clay. Waste clay is pumped to a settling pond. Sand and sand-sized phosphate particles - called "flotation feed" - are put through a process which uses chemical reagents, water and physical force to separate the sand and phosphate. Remaining sand is pumped back to the mine where it will be used to restore the site when mining is complete. The rock is trucked to chemical processing plants, like Piney Point. |
 |
Phosphate ore must be chemically processed before it can be used as a water-soluble fertilizer. Mixing it with sulfuric acid creates phosphoric acid that's used in fertilizer. When sulfuric acid reacts with phosphate to form phosphoric acid, it produces a slightly radioactive byproduct known as phosphogypsum. According to the most recent figures from the Florida Department of Environmental Protection, there are a billion tons of phosphogypsum stacked across the state and 30 million more tons are generated every year. Because it is radioactive, federal regulations ban its use in almost every situation. However, several pilot programs show that it may be a cost-effective alternative to fill material used for building roads. |
 |
Reclamation efforts developed over the past 30 years have been so successful that thousands of acres have been donated to local governments for parks. Providing habitat for wildlife also is a top priority, and researchers have identified 348 species of animals using reclaimed phosphate mines including the threatened scrub jay. |
 |
Florida provides 75 percent of the phosphorous used by U.S. farmers and about 25 percent of world production. Critical for root and flower development in all plants, phosphorous is quickly depleted in soils and must be replenished regularly if fields are to remain fertile. |
Construction of desal plant on track
Construction is on schedule at the Tampa Bay Seawater Desalination plant near Apollo Beach. When it opens in March 2003, it will be the largest desalination plant in the Western Hemisphere. Shown here, a crane operator is preparing to lift one of the 128 cones that will be installed in the plant's pretreatment system. The fiberglass cones, which are approximately six feet wide at the top, contain fine sand that will remove suspended solid materials and organics from seawater before it enters the reverse osmosis process. |
Top
|
