MEETING DISCHARGE REQUIREMENTS IN
PHOSPHATE MINING OPERATIONS
N. R. Greenwood, Consulting Engineer
S. Muehlberger, Chemist
Bromwell Engineering
Lakeland, Florida 33803
S. E. Lasda. Technical Service Engineer
Technical Service Department
Industrial Chemicals Division
Allied Chemical Corporation
Solvay, New York 13209
INTRODUCTION
The phosphate mining industry in the United States has experienced much change
during the 90+ years of its existence. This industry has literally evolved from a "pick and
shovel" industry to a sophisticated, highly mechanized, capital-intensive mining operation.
Technological innovations have greatly affected every facet of this industry and today's
mining operations bear little resemblance to their evolutionary antecedents.
The phosphate industry in the United States is large by world standards. The United
States is a major contributor to world phosphate production. In 1977, for example, the
U.S. was responsible for over 40% of total world production with an output of 47 million
metric tons of phosphate rock. The vast majority of this material (80%) was produced
from Florida "land pebble" mining operations of the type discussed in this chapter. The
remainder of U.S. production came from mining operations in North Carolina and the
western states.
Presently, phosphate rock production in Florida includes the following operations:
1. strip mining of ore or matrix;
2. slurry and transport of ore to beneficiation plant*;
3. phosphate pebble rock separation*;
4. flotation operations*;
5. drying; and
6. waste disposal and reclamation.
The beneficiation process (operations 3 and 4) is a means of separating the phosphate
rock from the sand and clay fractions of the matrix. Prior to the implementation of
flotation as part of the mining operation only the pebble rock phosphate was recovered,
leaving about half of the phosphate fines as a part of the spoil.
As noted, modern phosphate mining operations require the use of large amounts of
water to transport and classify the phosphate ore. Beneficiation operations presently
employed contribute greatly to the water demand of this industry. Although the industry
does recycle the water used in these operations, additional groundwater is utilized for
operations that require high quality feed water. Present groundwater use by the Florida
phosphate industry exceeds 783,000 m3/day (207 mgd).
Current water management practice by the phosphate industry involves the construction
of large impoundments to contain waste clays and to serve as reservoirs for recycle water
•Denotes large water requirements.
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