Volatility of Arsenic in Contaminated Clay at High Temperatures

Experiments were conducted in a tube furnace on the volatility of arsenic from contaminated kaolin clay. The experimental temperatures ranged from 522 to 1125°C. The gas compositions used were nitrogen, oxygen and nitrogen, carbon monoxide and nitrogen, and hydrogen chloride and nitrogen. At 522°C, 10 to 22% or less of the arsenic volatilized in all experiments. At 1125°C under inert and oxidizing atmospheres, about 40% of the arsenic volatilized. Arsenic volatility was higher for the reducing and the hydrogen chloride-containing atmospheres. At 950°C and residence times of 1 h or longer, 80% or more of the arsenic was lost for both the reducing and the hydrogen-chloride containing atmospheres. At 1125°C, arsenic volatilization ranged from 82 to 92% for the reducing atmosphere and 91 to 98% for the hydrogen chloride-containing atmosphere. The low arsenic volatility in the oxidizing experiments is similar to results in pilot- and full-scale incinerator tests.