Environmental loadings of long term sulphur storage: processes and controls

Elemental sulphur (So) is produced at petroleum refineries as a byproduct and a decrease in So prices has forced tens of mega-tonnes of So to be stockpiled at industrial sites. However, long-term storage of So blocks poses a potential for contamination of surface water and groundwater because of the oxidation of So to H2SO4.Two key controls on the environmental loadings of So blocks are the availability of oxygen and temperature.
Three large scale So pilot blocks were constructed to evaluate the effects of controlling factors on the oxidation of So blocks and to test the effectiveness of cover technologies. One pilot block was left exposed to the environment while two others were covered with cover material of various thicknesses to keep the underlying So blocks either insulated or saturated. So block temperature, availability of oxygen and drainage water chemistry data were measured over a period of three years.
The analysis of So pilot block data indicates that the pilot blocks would serve as useful analogues to commercial scale blocks. Pilot blocks temperature and oxygen profiles with depth indicate that the selected cover material could not control the temperature and the ingress of oxygen within the So blocks below the oxidation reaction. As a result, environmental loadings would remain a concern for the above ground sulphur storage sites.