51    HIGH PROFITS FROM POND WATER
Steven Weiss, Director of Sales and Marketing
Richard Dennis, Manager, Process Applications
Advanced Separation Technologies Incorporated
Lakeland, Florida  33801
BACKGROUND
Most of the phosphoric acid industry views pond water as an expense and necessary part of their
plant operation. Each day environmental factors are placing greater emphasis on cleaning the ponds
and reducing environmental pollution. Those companies which resist change and fight the clean-up
program redestined to become defunct.
Contrary to the above, there are a few companies who consider pond water as a valuable source of
profitable products. One such company is Advanced Separation Technologies (AST), a subsidiary of
Florida Progress Corporation. AST views pond water as a source of almost infinite SiF6, P04, and
S04 ions, worth $1 billion.
MARKET FOR POND WATER IONS
The key to success is finding ways to extract these ions and doing something valuable. For the SiF6
ion, the logical use is to make Si02 and fluorine compounds. S04 is a valuable ion in making
phosphoric acid and P04 can be easily employed in the existing phosphoric acid product line.
Si02 is an interesting product. In crystalline form, it is used in abundant quantity but sold at a low
price and normally at minimum profit. In its amorphous form, Si02 becomes a very valuable product
which sells between $800 and $4,000/ton. The U.S. market is 150,000 tons valued at $180 million.
Fluorine is also a widely used chemical species used to make hydrofluoric acid and fluorine
compounds. This class of chemicals account for 600,000 tons of product in the U.S. valued at $900
million.
In the world, there are only two primary sources of fluorine, fluorspar rock and phosphate rock.
99% of fluorine products are made from fluorspar rock which sells for $150/ton. Only l"/n is made
from the phosphoric acid by-product, fluorosilicic acid (FSA), which sells for $100/ton. Just think of
using the fluorine from pond water and buying it for $0/ton.
Over $1 billion of chemical products generating $200 million profit can be made from the SiF6 ion
found in pond water. The challenge is to economically extract the SiF6 and convert it into amorphous
silica and fluoride compounds.
THE ISEP* CONTACTOR
AST developed the ISEP* Continuous Contactor for adsorption and ion exchange applications.
Among its many benefits and features, the ISEP* allows an economical ion exchange for high
concentrations (300-150,000 ppm) of chemical species (Figure 1). The ISEP* uses a slow-moving
carousel arrangement to continuously and simultaneously feed the to-be-treated liquid stream along
with ion regeneration. The ISEP* allows ion exchange to be used economically in applications such as
extracting SIF6 for pond water.
HF PROCESS DESCRIPTION
The AST fluoride recovery process is designed to recover fluoride from the acidic pond water
circulated in a wet-process phosphoric acid plant. The process employs the use of the ISEP* continuous ion exchange system to concentrate the fluoride in the form of fluorosilicate ions. The concentrated fluoride-bearing solution exiting the ISEP* is further treated to produce high purity silica,
anhydrous hydrogen fluoride, and/or fluoride salts.
46th Purdue Industrial Waste Conference Proceedings, 1992 Lewis Publishers, Inc., Chelsea, Michigan 48118.
Printed in U.S.A.
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