Phosphogypsum Management and Opportunities for Use

Keywords: phosphogypsum, risk analysis, public good, stacking, plaster board, road construction, phosphoric acid.

The ‘wet process’ for producing phosphoric acid creates 5 tonnes of phosphogypsum (PG) (calcium sulphate) for every tonne of acid. Billions of tonnes of PG have been produced to date, much stored on land in stacks or piles. Some 160-200 million tonnes of PG are likely to be produced every year for the foreseeable future. Is it a toxic waste, or a valuable resource?

Over 50 possible uses for PG have been documented, with potential for large scale application in agriculture, especially beneficial to sodic soils, construction, road building and waste management, notably landfill and remediation. What are the barriers to use? The research effort is fragmented, and there is a lack of awareness beyond the research community itself that such a set of viable options exists; there are restrictive regulations concerning the naturally occurring radioactive material (NORM) in PG, especially in the United States; inertia in industry practices resists change; and there are inconsistencies and failures at the level of policy-making and societal communications. The successful use in Spain of PG from Huelva, approved in 2005 as a licensed fertiliser following five years of close monitoring by the University of Sevilla, demonstrates to contemporary standards of scientific risk assessment and stakeholder-driven policy-making that PG can be managed successfully if understood as a co-product of phosphoric acid and regulated accordingly. A consequential benefit will be to prevent a permanent legacy of billions of tonnes of PG stacked in perpetuity, all over the world.

The paper reports on progress to date made by the project ‘Stack Free by ’53?’ (2005-2011); one project goal is to create a consensus-based strategic policy framework for managing PG, worldwide. This framework is characterised as one of ‘regionality’, in which universally accepted standards, especially regarding public and environmental health, and peer-reviewed, readily available best practices are used as a basis for regional decision-making on PG management and potential use.

It argues that there is considerable urgency to reach a new ‘point of equilibrium’ (a term from John Nash, Nobel Prize winner) on PG: the increasing negative externality cost of storing or disposing of PG, especially the practice of stacking as mandated in the United States by the EPA 1989 rule, puts at risk the commercial viability of a strategic industry integral to global food production. This risk is acute as the industry is entering a period of profound and rapid change and one we all have an interest in averting.

Prof Julian Hilton, Aleff Group, 53-54 Skylines, Limeharbour, London E14 9TS, UK.

53 pages, 14 figures, 4 tables.