Precursors of volatile organic compounds emitted during phosphorite processing

The composition of solvent-soluble organic matter of phosphorite, which is a precursor of volatile organic compounds emitted by the fertilizer industry, was studied. A benzene-methanol mixture and chloroform were used for the extraction of free and bound bitumen from phosphorites, respectively. The separated bitumen fractions were characterized qualitatively by GC-MS and quantitatively by GC-FID. n-Alkanes, n-alkenes, fatty acids and isoprenoids were identified in the extracts. The main components were n-alkanes and n-alkenes, constituting over 80% of the total bitumen determined. An unexpected presence of n-alkenes only in the free bitumen fraction was found. The possible source of ill-smelling substances evolved during treatment of phosphorite with H₂SO₄ was discussed.