From: Jim Puckett
For many years all over the world phospho-gypsum has been a problem waste of the fertilizer industry. The biggest concerns I cans see are the cadmium and radioactivity (see excerpts below). Of these for building materials the radioactivity is probably of biggest concern as it will expose the inhabitants of dwellings made from the materials.
GAMMA DOSES FROM PHOSPHO-GYPSUM PLASTER-BOARD
R. S. O'Brien
Abstract-The use of phospho-gypsum plaster-board and plaster cement in buildings as a substitute for natural gypsum may constitute an additional source of radiation exposure to both workers and members of the public, both from inhalation of radon progeny produced from radon which is exhaled from the plaster-board and from beta and gamma radiation produced by radioactive decay in the plaster-board. The calculations presented in this paper indicate that if phospho-gypsum sheets 1 cm thick containing a 226Ra concentration of 400 Bq kg-1 are used to line the walls and ceiling of a room of dimensions up to 5 m x 5 m x 3 m, the annual effective dose from gamma radiation for a person continually occupying the room should not exceed approximately 0.13 mSv. This compares with a measured annual average effective dose from gamma radiation in Australian homes of 0.9 mSv. The annual effective dose from such thin sheets is directly proportional to the concentration in the plaster-board.
Health Phys. 72(1):92-96; 1997 Key words: dose; gamma radiation; 226Ra; radon
The Decommissioning of Phosphogypsum Tailings in Alberta
By: Glen W. Norlander
Supervisor: Dr. Dixon Thompson
Due to the presence of uranium daughters and other contaminants, the conversion of phosphate rock to fertilizer may be of significant contaminants that may preclude a future use of the tailings and the surrounding area after decommissioning are identified. A field study on the phosphogypsum tailings at the Western Co-operative Fertilizer Ltd. plant in Calgary, Alberta investigated one measuring the radon flux using passive activated charcoal collectors. Theradon flux was then used as the governing basis for the design of a proposed cover to isolate thecontaminants.
The study reveals that radon, dust, particulates and gamma radiation would preclude a future residential use of the tailings area and the adjacent land within 800 m of the tailings. Earth or liquid covers could reduce contamination leaving an inactive tailings area enough to technically allow some reduction to the 800 m setback distance. However, the inability to guarantee the chosen cover's integrity over the very long term would preclude a residential end use for the area.
The study also reveals that discharges of radon, dust and particulates from uncovered tailings will increase when the tailings are not in active use. The instability of the tailings will forestall the placement of inflexible covers designed to reduce radon flux, and thus dust drying of the tailings occurs. Drying times exceed two years.
This study was supported by Alberta Environment and Western Co-operative Fertilizers Limited. It compliments measurements made by Senes Consultants Limited on behalf of the Atomic Energy of Canada, Low Level Waste Management Office, in the national study into the decommissioning of phosphogypsum piles.
The transfer of phosphoric acid production: closures in Europe and expansion in Morroco
Phosphate, in the form P205, is a nutrient for plants and a building bloc in food production. Modern intensive agriculture boosts natural phosphat levels in the soil through the addition of the phosphate fertilizers. The production of this chemical fertilizer is one of the many stages in the food production chain in which this nutrient continually changes shape. Many environmental problems arise throughout the entire chain, one of which is the production of phosphoric acid, which is particularly well-known for the discharge of waste gypsum into surface water and the release of the highly polluting substances, phosphorous, cadmium and radon-226, into the environment. For every ton of phosphoric acid (P205) produced, five tonnes of unclean phospho-gypsum is discharged.
In the 1980s, Western European governments exerted their authority to stop such discharges, demanding a reduction in the quantities of free phosphorous drained because of its eutrophic interaction with surface water. Many local governments demanded a total halt (mostly in phases) to the discharge of cadmium - an EC blacklisted substance.
At first, the Western European chemical fertilizer industry responded with delay tactics. They began researching alternative methods for processing the gypsum.They looked into storage on land, as is done in the United States, and into reprocessing the waste into building material. The largest chemical fertilizer producer in the world, Norsk Hydro, initiated an ostensibly serious effort to develop a new cadmium cleansing technique at their plant in Vlaardingen, the Netherlands. The second largest, Kemira, offered to modernize its entire plant in Rotterdam in exchange for a promise by the local authorities to freeze
At the end of the 80's, in order to meet the stricter discharge standards, many producers in Western Europe switched to a cleaner raw material, low-cadmium phosphate rock. In three European locations producers switched to less environmentally harmful nitrophosphate production methods. These were Norsk Hydro in Porsgrunn (Norway), BASF in Antwerp and Chemie Linz (Austria). The Western European phosphoric acid producers were also riddled with economic problems. In 1988/89 the Moroccan state-owned concern, OCP, started expanding its production capacity since Morocco can benefit from cheap phosphate ore mined on its own territory.
A global glut arose at the same time that Western European demand for phosphate fertilizer shrank and prices begun to dive. Cheap imports from North Africa snatched the market from European producers and Morocco is still expanding capacity to meet export markets. In 1996, total world phosphoric acid production capacity will have risen by 1.9 million tonnes. Along with the continuing decline in the use of chemical fertilizers in Western Europe, this bodes ill for the European phosphate fertilizer industry. These negative market prognoses have forced corporations to close production units.
From January 1992 to April 1993 alone, 1.35 million tonnes of P205 phosphoric acid production was abandoned in Western Europe. That is more than one third of the total capacity, a decrease far in excess of the decline in the market and the oversupply caused by the expansion of competing nitrophosphate fertilizer production. Imports of phosphoric acid (or phosphate fertilizer) from Morocco (in particular) will have to be brought in to meet the needs.But the result will be a surge in pollution in Morocco. The flood of highly polluted phosphoric gypsum is being pumped, untreated, straight into the Atlantic Ocean. Thus closures in Western Europe have only resulted in a shift pollution to Morocco. In the end the environmental cause has gained nothing.
--From The Elusive Saviours, Transnational Corporations and Sustainable Development by Hans Heerings (CONTRAST Advies) and Ineke Zeldenrust (SOMO)Elusive Saviours