A primary operation in the transformation of iron ore to steel is the production of pig iron in blast furnaces, which emit enormous quantities of gases that have fuel value but which also produce suspended solids in liquid wastes. These suspended solids are the principal pollution source. Dry cleaning of blast furnaces in all stages eliminates wash water use and is the most effective remedial measure, although involves complicated operation. The remedial measure usually employed is the removal of the more readily settleable material from the gas wash water in sedimentation tanks providing 40 to 120 minutes detention. Material removed in the settling units is dewatered and sintered, then recharged to the furnace, providing a definite economic gain. Operation of furnaces under top pressure, within certain limits of blast volume, reduces gas velocities in the furnaces and consequently dust production.

Cover title. "Review copy." "October 1951." Includes bibliographical references.