Humboldt began as a supplier of mining machinery in Deutz, Cologne, in 1856. It was merged with the car manufacturer Motorenfabrik Deutz in 1930 to form Klöckner Humboldt Deutz (KHD). The cement equipment activities of this company were merged with the Bochum firm WEDAG in 1972 as KHD Industrieanlagen AG, re-named KHD Humboldt Wedag AG in 1979.
The company came to prominence in Britain after their post-WWII development of the Humboldt Preheater - the first successful suspension preheater system. Five KHD kilns were installed. The company continues as a world-wide supplier.
See KHD website.