Phosphogypsum
Phosphogypsum (calcium sulphate) is a naturally occurring part of the process
of creating phosphoric acid (P2O5), an essential component
of many modern fertilizers. For every ton of phosphoric acid made, from
the reaction of phosphate rock with acid, commonly sulphuric acid, some
four to five tons of phosphogypsum are created. The amount of phosphogypsum
being produced each year closely mirrors therefore, the industrial output
of P2O5.
Managing Phosphogypsum
There are three options for managing phosphogypsum:
- disposal or dumping
- stacking
- use – in, for example, agriculture,
construction, or landfill.
In some jurisdictions these options are constrained. For example in the United
States, option 2, stacking is the standard procedure,
with limited exceptions for certain types of phosphogypsum, for use, for example,
in peanut farming.
In other jurisdictions, dumping is permitted, mostly into open waters such
as the Atlantic Ocean.
In many jurisdictions where a mixture of use and disposal is common practice,
changing environmental legislation is causing a new emphasis on stacking in
the short term, and on potential beneficial uses in the longer term.
Piney Point, Tampa Bay, Florida – A
Reference Case for Stack Closure
In the world’s largest phosphoric acid producing area, central Florida,
the phosphogypsum stack has become one of the dominant features of the landscape.
In fact, Florida has some 20 stacks in all, of which many cluster along side
State Road 60 which runs from Tampa to Bartow and then further East.
Following the bankruptcy of Mulberry Phosphates Inc. in 2001, one of the
stacks owned by that corporation, located on Piney Point on the edge of Tampa
Bay started to pose a significant environmental threat as a result of the very
large quantity of acidic water stored on top of the Piney Point stack – some
1 billion gallons. In a year of high rainfall, a crisis occurred when
the water level rose above the safe “freeboard” limit adopted for
such a stack. Since then, some $300 million US has been spent on rectifying
the problems of the stack, by impounding the stacks with a lined cover to prevent
water recharge. In addition, treatment by lime neutralization of the
voluminous acidic pond water so as to render it suitable for discharge both
to Tampa Bay and also by discharging via barging into the Gulf of Mexico has
dramatically reduced the water volume and transformed the environmental liability
of the site.
The longer-term consequence of the Piney Point episode has been to draw attention
to wider issues concerning the costs, technical challenges and the environmental
and legal liability issues involved in the management of both active and closed
stacks.
The End to End Process 
A key premise of this project is that for a solution to be found to the challenges
posed by phosphogypsum, and the closely associated issues of process water
management, an “end to end” view needs to be taken. At least four
main stages apply:
Mining
and beneficiation
Processing
Use and
uptake in humans, animals and plants
End points,
in the environment, or in construction.
Outcome
Can phosphogypsum be safely regarded as a resource, rather than as a waste
with no commercial value? Can concerns about the presence of naturally occurring
radioactive materials (NORM), and other potentially harmful components such
as cadmium, in the source rock and the processed gypsum be sufficiently met
that phosphogypsum can be licensed as a product accepted again in international
commerce? If not, can a single best practice standard be adopted for managing
the phosphogypsum legacy in a safe way?
Participants and Sponsors
This project is designed to benefit Participating and/ or sponsoring organisations
as of July 2005 include:
Aleff
Group, London, UK and, Lakeland, Florida
Dr. Phosphate
Inc. Lakeland, Florida
Florida
Institute of Phosphate Research, Bartow, Florida
Rothamsted
Research, UK.
Numerous regulatory authorities are being consulted about the project.
A number of other organisations are currently in the process of joining the
research effort.
There is also ongoing collaboration with the International Fertilizer Association,
Paris.
Links
Aleff Group
FIPR - Florida Institute of
Phosphate Research
Rothamsted Research
IFA - International Fertilizer
Industry Association
Brief Project Overview - 2005-2011
For
further information please contact:
Julian Hilton
Aleff Group
53, Skylines
Limeharbour,
LONDON E14 9TS
Tel: + 44 20 7515 9009
Contact Julian Hilton
www.aleffgroup.com
Vaughn Astley
Dr. Phosphate, Inc.
2120 Clubhouse Road,
Lakeland, Fl 33813, USA .
Tel: 1-863-619-9765
Contact Vaughn Astley