Krupp-Renn Process

a modern modification of the blooming process, by which iron is produced directly from ore (without a blast furnace); it is intended for processing low-grade, poorly dressable, or polymetallic iron ores in rotary tube furnaces to produce bloom. The process was proposed by the German metallurgist F. Johansen and was first performed at the Krupp factory in Magdeburg (Germany) in 1931–33. From the 1930’s to the 1950’s more than 65 installations with rotary furnaces (60–110 m long and 3.6–4.6 m in diameter, with a capacity of 250–800 tons of starting ore per day) were built in a number of countries. The process lost its industrial significance because of its uneconomical nature and low quality of output.