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.

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.

[1] The latter also developed a technology to industrialize the process of decomposing mutually equivalent amounts of potassium carbonate and sodium nitrate which was discussed by chemists since 1840s.

[2] As a location for the new factory they chose what was then the small village of Kalk (incorporated into Cologne in 1910) on the right bank of the Rhine.

After purchasing the premises of the former iron foundry Biber & Berger construction began and three months later, in February 1859, production started.

[3][4] As the new company flourished several adjacent lots were purchased in 1860 to expand the production facilities and to maintain the regional market leadership in potassium nitrate.

To reduce transport costs the two founders decided to build two potassium chloride factories in Staßfurt and Leopoldshall where they had acquired a second salt mine.

[9] In 1864, the factory began the production of the fertilizer superphosphate, produced from phosphorite from a newly acquired mine in Nassau an der Lahn.

[11] In 1867, the company incurred financial losses from a bad investment in the United Kingdom and declining demand for its products.

Magnesium sulfate was primarily intended for the export to the United Kingdom, where it was used as a drying agent in the textile industry.

The new product and an improving market for potassium nitrate helped the company to overcome the financial crisis in 1870.

After the death of the founder Julius Vorster on 10 October 1876, the new owners converted the company into a limited partnership (Kommanditgesellschaft).

The company was also one of the owners of the coal distillation plant Ammonium GmbH in Weitmar near Bochum and held interests in domestic and international Thomas steel mills producing slag.

Despite the lack of workers the company also expanded into the new market for animal food by treating straw with sodium hydroxide.

[20] After the Hitler's rise to power in 1933, the company gradually began to concentrate on raw materials for the production of explosives.

After the outbreak of World War II, with the male workforce in military service, women were conscripted for work at the company.

On 6 March 1945, the grandson of the founder, Fritz Vorster Jr. closed the factory after 80 percent of the production facilities had been destroyed.

[22][23] In August 1945, only three months after the end of the war the Chemische Fabrik Kalk began to produce burnt lime for the purpose of bartering.

After the takeover the Salzdetfurth AG began to modernize the production facilities and build for example a new, 120 metres (390 ft) tall chimney that helped alleviate the odor pollution from sulfurous exhaust fumes.

In 1974, the factory had 1800 employees, had a revenue of 400 million DM and was active in the production of sodium carbonate, calcium chloride, fine chemicals, phosphate for animal feed and fertilizers.

The company posted increasing financial losses, partly due to its locational disadvantage as all raw materials and all final goods had to be transported by truck from the factory to Cologne's Rhine harbor.

Employment fell from 1400 employees in 1985 to 830 in 1990, with the factory only producing sodium carbonate, calcium chloride and phosphate for animal feed.

[30] The fall in prices was partly due to the lifting of anti-dumping on sodium carbonate imports from the American Natural Soda Ash Corporation (ANSAC) by the European Commission.

Another factor in the worsening financial situation was an antitrust fine of US$1.38 million imposed by the European commission for participating in a sodium carbonate cartel together with Solvay and Imperial Chemical Industries.

In 2005, the Köln Arcaden shopping mall opened, with the parking garage build around the historic water tower.

Other planned projects include residential and office buildings, retail space and an urban park.