Pyrites containing 47.6% is burned in a sulfuric manufacturing plant. the cinder contains 2% present as fes2. the burner gas analysis is 7.86% so2, 81.33% 02. the s02 does formed is further oxidized by trioxide by conducting the gases mixed by with air over a catalytic mass of platinum black at the converter. the converter gas analysis: 0.44% so2, 7.97%02 and 91.59% n2. the so3n the converter gas was absorbed in the absorption tower using 10% oleum where 95% s03 producing 20% oleum. calculate: %ffes2 in the feed pyrites, %fes2 in burner gas, %x's air. calculate also per 100 kg feed: kg cinder, knlair used in the burner, kn secondary air used in converter and kg product (20% oleum)