Chromium analysis at a ferrochrome smelter, a chemical plant and a refractory brick plant

Techniques were developed to sample and analyze the Cr content of particulate samples with emphasis on determining the concentration of the carcinogen Cr+6. Cr+6 is extracted to alkaline solution and analyzed colorimetrically. Residual particles are extracted with acid solution to remove soluble Cr+3, which is determined by atomic absorption spectrometry. This methodology was tested on samples from three diverse types of sources: a ferrochrome smelter, a chemical plant, and a refractory brick plant. Identical quadruplicate samples were collected to determine accuracy and precision of the collection and analysis procedures, and extraction of Cr+6 and Cr+3. A statistical analysis revealed that the precision of Cr+6 analysis is comparable to that of the particulate mass determination. The stability of Cr+6 in particulate form and in solution was determined. Size resolved particulate samples were collected to determine the particle size versus the Cr+6 content. At the ferrochrome smelter and the chemical plant the majority of the Cr+6 was contained in the respirable particles. The accuracy and completeness of the chemical methods employed were verified by neutron activation analysis, x-ray photoelectron spectroscopy, and scanning electron microscopy-energy dispersive x-ray analysis