Experimental evaluation of hydrogen chloride (HCl) absorption by cement raw meals at low temperatures, using fixed-bed tests

The HCl absorption by cement raw meals was experimentally evaluated in the temperature range 100-180℃, using a fixed-bed set-up and gas phase HCl content between 50ppmv and 200ppmv. The effects of temperature, gas phase composition and dispersion of raw meal particles on HCl absorption capacity of raw meals were studied.

The obtained data are consistent with our interpretation of HCl absorption mechanism based on a surface saturation phenomenon that corresponds to a certain specific HCl absorption capacity of raw meal. The experimentally observed active compound conversions were significantly less than 1%. The dilution of raw meal samples using fused silica with particle size range 50–100 μm increased the apparent HCl absorption capacity of raw meal 10 times due to the elimination of raw meal particle agglomerates.

The HCl absorption was slightly enhanced as the temperature was decreased from 180℃ to 100℃ in the case of dry gas phase tests. A dependence of raw meal HCl absorption capacity on the raw meal moisture content was detected at the same experimental conditions. The presence of 5% v/v H2O in gas phase increased the absorption capacity of raw meal A by 25% at 180℃ and by 61% at 100℃ relative to the absorption capacity from dry gas phase.

The presence of 3% v/v O2 and 30% v/v CO2 in gas phase did not have any apparent effect on the HCl absorption in the investigated temperature range.