The raw materials of Portland cement often contain chromium partially converted to hexavalent chromium by the kiln highly oxidizing and alkaline conditions. Chromium VI is often present in 5 to 20 ppm proportions. It is reported to cause skin irritation, which is the primary reason behind the European Community’s introduction of the obligation to maintain levels of soluble chromate in cement below 2ppm.
Different chromium VI reducing agents are supplied by Holderchem based on either stannous sulfate, ferrous sulfate heptahydrate, or antimony trioxide. Ferrous sulfate-based products are sensitive to moisture and require higher dosage rates than stannous sulfate-based products, which have better reduction capacities but are more expensive.