Hart on the Alz

The history of calcium cyanamide production began with the foundation of the Bayerische Stickstoffwerke AG (BStW) in 1908. It was situated in the area between the Inn and Salzach rivers, known today as the „Southeastern Bavarian Chemistry Triangle”.

The crucial material - carbide, made from calcium and coke - was initially produced in the carbide factory in Schalchen near Trostberg (in operation from 1910 to 1925), and then, starting 1919, mainly in Hart on the Alz, 15 km further north. For both sites, the water providing the source of energy was the deciding factor: the construction of power station III (Carowerk) at Hirten-Margarethenberg and the 14.5 km long canal between power station II (Schalchen) and power station III created the conditions for the Althart carbide factory (today Hart II). Six 3,000 kW carbide furnaces were used in the production. A 5 km long industrial railroad to the nearest train station facilitated distribution.

Hart site, administration building, 1960ies

These new activities were financed by the German Reich. Bayerische Kraftwerke AG (BKW) was therefore set up in 1920 for legal and financial reasons. The business and operational management at BKW reported to the BStW. From 1925, these two companies agreed to run a joint operation. This merger resulted in 1939 in the foundation of Süddeutsche Kalkstickstoff-Werke AG (SKW).

Losing the Oberschlesische Stickstoffwerke (OStW) in Chorzow/Königshütte to Poland in 1922 meant that calcium cyanamide production in Bavaria had to be increased and, consequently, capacity for production of the initial component carbide also had to be expanded. The Neuhart (today Hart I) carbide factory was under construction from 1922 to 1924. Initially, it had six 10,000 kW carbide furnaces whose output was doubled in the following years. Furnace 7 was built from 1954 to 1956, the first closed carbide furnace in the world. From 1961 to 1963, Furnace 1 was also converted to the closed type.

Garching housing development, 1920ies

In the 1920s, 180 residential units, the Garching/Alz works housing development, were built for the labor force, which was also growing rapidly. The development also included social facilities, such as an elementary school and a gymnasium.


Hart sustained no damage from bombs during the war. 1944 saw the introduction of metallurgical production that developed without any setbacks to become an important product for the site. Production started with ferrosilicon (FeSi). This was required by the National Socialist planning authorities to replace production lost as a result of the war. However, significant quantities were not achieved until the 1950s with the construction of new production plant (electric furnaces). In 1949, calcium silicon (CaSi) and other specialty metals followed. These were used mainly in the steel industry as additives. In 1955, more expensive, innovative foundry alloys, such as master alloys and inoculant alloys, were introduced. A further innovation for the foundry industry followed in the1980s. Cored wire technology allowed precise administration of additives for processing and innoculant wires, in terms of quantity, time and location.

Environmental protection

Increased air pollution and the growing significance of environmental protection in the post-war decades prompted considerable investment and constant improvements in Hart. 1956 e.g. saw the first closed carbide furnace (35,000kW) in the world with a gas cleaning system put into operation. Ceramic filters, which were also a new development, allowed the carbon monoxide created to be trapped, cleaned and reused as a valuable process gas. For this purpose, a carbon monoxide pipeline was laid to Schalchen and Trostberg, where the gas was used as a valuable reaction partner in calcium cyanamide derivative chemistry.

At the beginning of the 1980s, measures to remove dust from the air represented a further milestone in environmental protection. Until then, thick clouds of smoke and resulting deposits of fine dust had been the hallmarks of the factory in Hart and its surroundings. Fine fabric filters were used to remove the dust effectively from the production plants (carbide and alloy furnaces). The dust emissions (previously around 40t per day) were cut by 95 percent. In 1989/1990, even more efficient ceramic fiber filters replaced the carbon monoxide filters. In the 1990s it also became possible to granulate or compact this filtered dust so that it could be used as an additive in the construction industry.

Hart site, aerial view, 2001

Moving from bulk goods (FeSi and CaSi) to lower volume specialties, as well as increasing automation of labor-intensive processes, cut the numbers of employees at the Hart site from over 1,000 in the 1950s to around half of that in the 1970s. The remaining metallurgical activities with about 400 employees were part of AlzChem GmbH, founded in 2006. Late in 2009 financial investor BluO acquired AlzChem GmbH. With carbide and carbon monoxide gas Hart still makes an important contribution to supplying raw materials for the carbide-based calcium cyanamide derivate chemistry, which is a core of today's "Chemiepark Trostberg".