Phosphogypsum Radioactivity

Coupled with the energy consumption is the environmental effect from production of these binders. For every ton of phosphoric acid, 5 ton of phosphogypsum (calcium sulfate) is produced [15]. This waste can be recycled into value-added products such as gypsum board, but often there is a radioactivity issue. Some phosphogypsum contains radium and emanates radon gas. At the present time, such waste can only be disposed in a landfill. 

The background concentrations of radium in the subsurface material, before creation of the phosphogypsum piles, can be accurately estimated since longterm data are available 14.6], Interest in radioactivity in Florida dates back to 1942 through 1948, when there was an urgent need to find domestic sources of uranium. In addition, there has been environmental concern about radium in Florida for the last 20 years, and considerable data have been published, some of which are shown in Table 9. 

Hazardous Waste - Radioactive elements and heavy metals may leach if phosphogypsum stacks are not isolated from groundwater. 

Mild radioactivity is usually found in waste slag from the electric furnace process for making elemental phosphorus (Chapter 4.1) moreover, radioactivity could sometimes be present in the waste phosphogypsum from wet process phosphoric add (Chapter 5.2). 

A common problem is, however, the content of the radioactive element radium, which is a common impurity in many phosphorite deposits and which is carried forward to the products. This problem makes phosphogypsum particularly unacceptable for making constmction materials. The latter specifies less than 25 picocurie (a curie is a unit of radioactivity equal to the amount of a radioactive isotope that decays at the rate of 37 billion disintegrations per second) of radioactivity in the phosphogypsum. 

Installers of phosphogypsum plaster board can also be exposed to radium 226 and other radionuclides from the uranium 238 decay series in radioactive dusts from the plaster board. O Brien et al. (254) estimated potential doses to... 

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