Bone Valley
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The Bone Valley is a region of central Florida, encompassing portions of present-day Hardee, Hillsborough, Manatee, and Polk counties, in which phosphate is mined for use in the production of commercial-grade agricultural fertilizer. Florida currently contains the largest known deposits of phosphate in the United States.
Process
Large walking draglines, operating twenty-four hours a day in surface mines, excavate raw pebble phosphate mixed with clay and sand (known as matrix) using huge buckets which can hold more than forty cubic yards of earth. The matrix contains a number of chemical impurities, including naturally occurring uranium at concentrations of approximately 100 ppm.
The matrix is then dropped into a pit where it is mixed with water to create a slurry, which is then pumped through miles of large steel pipes to washing plants. These plants sift and separate the phosphate from the sand, clay, and other materials, and mix in more water to create a small granular rock termed wetrock. This wetrock, which is typically of little use in raw form, is then moved largely by rail to processing plants where it is treated. The final products include diammonium phosphate (DAP), monoammonium phosphate (MAP) and triple superphosphate (TSP).
Waste byproducts are stored in large phosphogypsum stacks and settling ponds, whose sizes are often measured in hundreds of square acres, and can be up to 200 feet tall in the case of large stacks. Phosphate processing produces significant amounts of fluorine gas, which must be treated by filtering through special scrubbers involving the use of silica.
Most of the final product (known within the industry as 'dryrock') are then transported by rail to facilities along Tampa Bay, where they are transloaded onto ships destined for countries such as China.
Phosphate product intended for domestic use is assembled into long trains of covered hopper cars for northbound movement.
History
In 1881, J. Francis LeBaron, a captain in the US Army, discovered fossilized remains of prehistoric animals in the bed of the Peace River. Captain LeBaron related this information to an associate, Colonel T.S. Moorehead -- who in turn began to do prospecting in the lower Peace River area.
Colonel Moorehead later acquired land along the Peace River near the village of Arcadia, establishing the Arcadia Phosphate Company in 1888.
By 1889, no fewer than twelve companies were mining phosphate along the Peace River. Through attrition, the number of companies were reduced to four by 1894. On December 31, 1894, the four surviving companies combined to form the Peace River Phosphate Mining Company. Their activities attracted the attention of the American Agricultural Chemical Company (known as Agrico) and in 1899, began to acquire Peace River Phosphate Mining Company stock.
In the early years, phosphate from the Peace River area was barged to Punta Gorda, or shipped by rail to Port Tampa. Other important ports were later established at Seddon Island, Boca Grande, and Rockport.
Today, there are only two companies which mine phosphate rock in the region, Mosaic Inc. (formed from the merger of IMC-Agrico and Cargill Crop Nutrition) as well as CF Industries. Recent years have seen a slump in the market, and Mosaic is seeking to mine properties further south.
Rail Service
For many years, the Bone Valley region received service from two major railroads, the Atlantic Coast Line and Seaboard Air Line. More than a few plants and mines saw the services of both railroad companies, such as the Ridgewood fertilizer plant located near Bartow, and the massive Pierce washer at Mulberry. It was not until the 1967 Seaboard Coast Line merger that the bitter rivalry was put to rest. SCL itself was later absorbed into CSX, who have since pursued an aggressive strategy of abandoning trackage.
Abandoned routes within the Bone Valley area include:
- Bowling Green to Arcadia (ACL)
- Arcadia to Boca Grande (SAL)
- Durant to Willow (SAL)
Risks of mining
Phosphate is a growing export to China, where it is used in fertilizer, but the consequences of mining it are borne in the Peace River watershed. Phosphate mining companies bore and scrape huge pits up to 60 feet deep over thousands of contiguous acres. More than 180,000 acres have already been mined in the Peace River watershed, and mining corporations are now seeking permits for another 100,000 acres - an expansion of more than fifty percent.
One byproduct of the extraction process is clay, which is stored in settling ponds which eventually comprise more than forty percent of a mine site. Some of these ponds can measure thousands of acres. Rain is trapped in these massive clay-laden ponds, rather than soaking into the soil to replenish underlying aquifers. This in turn, reduces flow in the Peace River. Since the 1960s, the average annual flow of the middle Peace River has declined from 1,350 cubic feet per second (cfs) to 800 cfs. Most of this flow reduction is due to phosphate mining. Each holding pond has been perceived as a risk that threatens water quality, public health, wildlife, and the regional economy. Dams restraining the ponds have overflowed or burst, sending a slurry of clay, containing uranium and radium into the river, and coating the riverbed for many miles with a toxic clay slime that suffocates flora and fauna. One such incident in 1971 killed over three million fish when two million gallons of phosphate waste swept into the river, causing an estimated five foot tall tide of slime that spread into adjacent pastures and wetlands.
On some occasions, clay slime spills have prevented the Peace River Manasota Water Supply Authority from using river flows for drinking water, forcing counties to seek water supplies elsewhere, or rely on stored supplies. On several occasions, the effects of heavy rains have created sinkholes beneath the settling ponds.
External links
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