Chemische Fabrik Kalk (CFK) (lit. Chemical Factory Kalk) was a German chemicals company based in Kalk, a city district of Cologne. The company was founded in 1858 as Chemische Fabrik Vorster & Grüneberg, Cöln by Julius Vorster and Hermann Julius Grüneberg and was renamed to Chemische Fabrik Kalk GmbH in 1892. At times the company was the second-largest German producer of soda ash and was with almost 2400 employees one of the largest employers in Cologne. For decades the chimneys and the water tower of the factory dominated the skyline of Cologne-Kalk.
In 1960 the company was acquired by the Salzdetfurth AG, which was later renamed into Kali und Salz (nowadays K+S) and became a subsidiary of BASF. All production facilities of the former Chemische Fabrik Kalk were closed in 1993, and the name Chemische Fabrik Kalk since then exists only as the name of a wholesale subsidiary of K+S. The factory was demolished and after the decontamination of the premises the new Cologne police departments headquarters and the Köln Arcaden shopping mall were built on the former factory premises.